I've been thinking of motorizing my TT-50 truing tool. The thinking is that it would allow it to run slower (I sometimes get impatient and run it too fast). It would make it run consistently, and I can enjoy a cup of coffee whilst it runs ("Look ma, no hands!").
Rich
Quote from: RichColvin link=topic=3339.msg20136#msg20136 date=1502548016
I've been thinking of motorizing my TT-50 truing tool. The thinking is that it would allow it to run slower (I sometimes get impatient and run it too fast). It would make it run consistently, and I can enjoy a cup of coffee whilst it runs ("Look ma, no hands!").
Rich
That sounds pretty cool!
(Bonus points if you can get it to run a sharpening jig back and forth)... ;D
LOL!
I was JUST thinking about this while writing my response to the truing tool conversation in my thread. Submitted that, come back to the thread list, and here this was haha
My thinking was that it would also eliminate any tendency to put pressure on the tool while turning by hand
This would be interesting to me as well. The idea of a very consistent movement where pressure is constant along with speed across the stone.
Here is an idea I picked up from Kurt Johansson.
Quote from: Elden on April 10, 2013, 03:47:09 AM
I am in the process of making another gizmo he mentioned. He made a wooden cup to fit on the knob (friction contact) of the TT-50. It has a spindle like piece fastened to it so that it can be chucked in a cordless drill. The cup is held in contact with the TT-50 feed advancement knob and is rotated with the drill on low speed. This gives a consistent and even feed rate.
For me that would be great as my left hand does not function well. I have to advance the TT-50 one handed. If it works well for me, I envision making the cup of rubber from an old forklift tire eventually. The cup possibly would be of metal with a rubber insert.
I got the wooden cup made and did not get any further with it. The wooden cup did grip the knob of TT-50 and would turn it when it was placed in contact by hand. I just never followed through connecting it to a cordless drill.
One would think that a high torque, low speed stepping motor with micro switches at either end and a selection switch would do a really nice job. Two (2) passes at a given depth should ensure that the surface is absolutely smooth. Selection switch would determine the speed across the stone - with four options: SB-250, SG-250 coarse, SG-250 fine and SJ-250. Granted, truing tool "this way" would be more expensive, but at least you'd know that each stone was 'trued' to what Tormek suggests, as they know/expect a stone to be in a certain condition for optimal function - likely quite a bit of engineering time. At a minimum, would suggest two passes to ensure that the both edges of the stone are addressed in both directions - three passes may be a bit much?
Perhaps one of the engineering folks at Tormek might chime in as to whether this might even be plausible (or not).
There was a post on youtube about an issue whereby someone only did one pass and experienced some anomalies. I don't recall the post, but there were three parts (separate videos) about the issue. Suspect that speed across the stone, combined with variations in pressure and potentially the number of passes - had an impact. One could easily see where this could happen.
Thoughts?
Quote from: justme on December 19, 2017, 05:52:10 AM
One would think that a high torque, low speed stepping motor with micro switches at either end and a selection switch would do a really nice job. Two (2) passes at a given depth should ensure that the surface is absolutely smooth. Selection switch would determine the speed across the stone - with four options: SB-250, SG-250 coarse, SG-250 fine and SJ-250. Granted, truing tool "this way" would be more expensive, but at least you'd know that each stone was 'trued' to what Tormek suggests, as they know/expect a stone to be in a certain condition for optimal function - likely quite a bit of engineering time. At a minimum, would suggest two passes to ensure that the both edges of the stone are addressed in both directions - three passes may be a bit much?
Perhaps one of the engineering folks at Tormek might chime in as to whether this might even be plausible (or not).
There was a post on youtube about an issue whereby someone only did one pass and experienced some anomalies. I don't recall the post, but there were three parts (separate videos) about the issue. Suspect that speed across the stone, combined with variations in pressure and potentially the number of passes - had an impact. One could easily see where this could happen.
Thoughts?
I don't think it needs to be that complicated. I have a model train speed controller that controls small DC motors, 14 VDC output. I have a small gearmotor from Jameco with a 200:1 speed reduction. At 12VDC it turns at 13 rpms, but with the train controller I measured it at 20 rpm. I have it for extracting bamboo fly rods from the varnish dip tube at rates from 1"/min. to 4"/min. I had to gear it down further, thus the timing pulleys. Oh, yeah, instantly reversible.
(https://forum.tormek.com/index.php?action=dlattach;topic=3339.0;attach=1477)
(https://forum.tormek.com/index.php?action=dlattach;topic=3339.0;attach=1479)
Using my forefinger and thumb on the output pulley, I could not easily stop the gearmotor. I know that is not as much pressure that I use when driving the truing tool across, so I am convinced even this small motor is up to the job. I will need to find one that runs at a higher rate but that should be easy. I've already looked.
The TT-50 takes 41 rotations of the knobs to traverse the full width of the feed screw but only about 36 to traverse the width of the stone. If I get a motor that runs at about 60 rpms, that would yield the faster rate of approx. 30 sec. The train controller will allow slowing it down greatly for slower traverses, easily up to the 90 sec. rate and probably more.
Don't know when I'll have time to play with this further as things are hectic in my life these days.
Rick
I was thinking purely "automatic". Turn on after setting speed and let it go to town without having to worry about it.
The motor sounds like an excellent start. A variac certainly provides option(s) for speed. I'll have to look into that Jameco motor - as I have a couple things where that would be useful. ;)
Rick,
I was thinking of something like an Rose Engine lathe overhead drive (here's a good article about one http://www.whidbeyworks.com/root/Ornamental_Obsessions_files/Overhead-Spring2008.pdf ). Your motor would work with that. And, adding micro switches to stop it at the end might make this a really cool option where you could start it and walk away (to grab a cup of coffee ...).
Rich
Start and grab coffee.... Perfection!
You could turn a threaded holder to fit in your metal lathe ( as long as the swing was greater than the diameter of your wheel);put the diamond dresser in the lathe's tool holder; and use the power feed to control the cross speed. :)
In my very low tech world, I just use a thermal lidded coffee cup and use the truing tool the regular way. My coffee stays warm.
Ken
Ken,
The original reason for 'my' commentary is the premise that an organic engine input (hands) likely would have an impact. For example, learned that the SJ-250 needs an *extremely* slow movement. (>90 seconds) otherwise, you'll end up with what appear to be "waves" on/in the stone. Resulting in the need to make multiple passes to "fix the fix". Seeing how something like that can occur, my preference would be to remove the organic component so that the results are consistent every time and correct the first time around. I also noticed that as you grab/rotate/change between hands trying to keep a constant movement/pressure - that on the SG wheel, not an issue. On the SJ wheel, it appears to be far more sensitive. Which my suspicion is that this fact had bearing on why/how the "wave" happened - not just speed across the stone. Something akin to a minor "torquing" of the tip on the stone. - Granted, some conjecture is involved and would be most amicable to thoughts on that.
Granted, I'm far "newer" at using the Tormek than [likely] the majority of folks on this site. However, learning a great deal and of course - learning through mistakes as well. (Fewer being the optimal goal). <sheepish grin>
Perhaps being "hopeful" that Tormek would produce an AC-based truing tool variant (as previously described) so that outside of setting height adjustment that there's far less potential for mistakes as part of one of the most critical maintenance tasks.
I use a coffee cup warmer - although it doesn't help with refills. ;)
When you get this perfected, figure out how to use the wasted heat from the Tormek motor to brew your coffee while the grinding wheel is absorbing its load of water. Oh by the way, figure out automation of the stone grading while you are at it. DC backup would be nice as well, the battery could charged while the Tormek is under idle or low load usage through a small generator inside the Tormek frame. :D
Quote from: justme on December 21, 2017, 07:39:55 PM
Ken,
The original reason for 'my' commentary is the premise that an organic engine input (hands) likely would have an impact. For example, learned that the SJ-250 needs an *extremely* slow movement. (>90 seconds) otherwise, you'll end up with what appear to be "waves" on/in the stone. Resulting in the need to make multiple passes to "fix the fix".
I'm just lazy.
Justme,
You make a very good point. Although I have owned an SJ-250 since 2010, I have not used it very much. This is not due to any fault in the stone. If you have read my posts over the years, you will know that I have spent most of my Tormek time testing and reviewing. My knives and woodworking tools have survived with just the traditional SG/leather three step.
I have trued my SJ. Among other things, I lent it to Rich Colvin for a test drive just before he purchased his. I had just trued it. As I recall, I thought the edge looked like new. Perhaps Rich will share his recollections. I am generally very cautious with truing, both with depth of cut and speed. Except for special situations, I traverse the stone in more than ninety seconds with no deeper than a half a number cut. I am on no production schedule, and I enjoy peeling the onion and watching the stone gradually become true.
I have thought the round plastic turning knobs are less than ideal for a continuous turning motion. I have wondered how a crank would work. Rich made a very nice looking crank for a jig he designed. I think a lighter duty crank similar to that would be useful for the truing tool.
I think I could be content with a single slow speed. Over the years I have accumulated a dozen wheels for my Tormek. (The non Tormek wheels were purchased for forum experiments.) The quick traverse method does make the wheel briefly. Switching to an 80 or 180 grit CBN wheel is a long lasting fix. They can be used wet or dry. (Add Hone Rite Gold when using them wet.) The quick traverse method is a useful trick and one I did know for many years. (I must have nodded off while reading that page of the handbook....) :)
If a motor arrangement would lead toward more regular truing, I think that is a worthy objective. My wheel can be quite stealthy in becoming untrue.
Keep thinking!
Ken
@Elden - love it! (got a good chuckle).
@Ken S - I would be apt to do more truing (likely Tormek would sell more grindstones as a result) of having a consistent means to ensure that the stone is true. I already had one experience where I had to re-do a knife because I didn't realize that there was a minor slope across the stone. This wasn't obvious until you looked at the resultant blade. Granted, I'm doing all of this for myself (not professionally), but having things "just right" is nice.
I believe RichKrung is onto something with the small stepper motor.
Quote from: justme on December 24, 2017, 03:09:40 AM
I believe RichKrung is onto something with the small stepper motor.
Justme,
You can just refer to me as "Rick K".
Got the motor I intend to use, or at least try first.
(https://forum.tormek.com/index.php?action=dlattach;topic=3339.0;attach=1481)
Have written down some key dimensions and have the computer out to start drafting and designing, but it is late, I just finished a seven hour drive, with my granddaughter, to be with
family for Christmas. So I won't get much done for a week.
Rick K
Justme,
I seem to recall Jeff Farris posting that he routinely trued his grinding wheel (SG-250) every time before reshaping a turning tool. Jeff is an expert turner.
I used my Tormek for several years before I felt comfortable using the TT -50 truing tool. A big part of that time lag for me was fear of wearing out or damaging my precious grinding wheel. Things improved when I started thinking of my grinding wheel as a long lasting consumable, like brake shoes.
Like you, I had several instances when my wheel looked true, but was causing problems because it was out of true.
Becoming proficient with the truing tool is not difficult. For me, an ideal training method would be instructor led and include truing the wheel half a dozen times in the class. Once you do it several times in a short period of time, like in an afternoon, it becomes second nature. Doing it once every year or two doesn't let the knowledge set in.
The stepper motor, perhaps with a flecible shaft, is a clever idea. The Unimat had a flexible shaft accessory. The motor had several pulley setups allowing very sliw RPM.
Ken
I am still in that "afraid to use the truing tool" too much phase, partially due to not wanting to wear it down too fast, but for at least one other reason. I am not yet comfortable with what the truing tool is truing to. As a machinist, I am accustomed to truing my machine tools to fairly precise levels (mostly my mill but also sanders and saws).
I have not made a study of it yet, but the primary standard I would use is placing a square (in my case, a precision machinist's square) on the side of the stone and looking at how square the top (grinding surface) is to the side. I'd then compare that to how square the USB is, in it's locked and working position. I've not yet looked closely at this, but it is possible that the USB is not square to the side of the stone, which is what this reference really is. I've thought about this a little, thinking that the USB's position is determined by the holes in the housing, secured by the locking screw. The vertical shaft of the USB being forced against inside diameter would determine its vertical alignment, which would project to the horizontal alignment of the USB, relative to the top surface of the stone. While everything I've seen so far regarding precision and quality of construction of the Tormek is excellent, it does not automatically mean the USB mount holes are in alignment with the side of the stone and therefore perpendicular to the top of the stone.
Trust but verify.
I would hold my square on the side of the stone and look at the surface of the stone. Shine a light behind it and look for any differences in light showing through. And then lower the USB to the top surface of the square and tool at how square it is, in its locked position to the side of the square. They are not necessarily the same (short version of the long winded above).
And then I wonder... What difference does it make... ? I've read about how the stone not being true has caused problems. I don't get it. Knife sharpening and other free-hand sharpening, one is guiding the knife (or whatever) along the surface (however square or not), watching the level of water build up along the surface. Square tool jig, if the stone has been trued to the USB, wouldn't it still produce a squared edge, regardless of how slightly un-square the USB and stone top surface might be to the side of the stone?
Just wondering,
Rick K
Rick,
I'm in your camp. Except for plane blades & chisels, the alignment of the USB to the stone isn't terribly critical. That is because most jigs moves freely along the USB. (I don't sharpen planer blades.)
But, as I sharpen the tools like bowl gouges, I find there are ruts or other unevenness left on the stone surface. Truing the stone gets it back to flat.
And as for using up the stone, i have had my Tormek for 15 years, and have fully consumed one SG-250 grindstone, and half of an SB-250 grindstone. The SJ stone I have is still 240-245 mm. So, I figure getting 10 years or so from a stone isn't too bad.
Rich
Quote from: RichColvin on December 24, 2017, 05:45:17 PM
Rick,
I'm in your camp. Except for plane blades & chisels, the alignment of the USB to the stone isn't terribly critical. That is because most jigs moves freely along the USB. (I don't sharpen planer blades.)
But, as I sharpen the tools like bowl gouges, I find there are ruts or other unevenness left on the stone surface. Truing the stone gets it back to flat.
And as for using up the stone, i have had my Tormek for 15 years, and have fully consumed one SG-250 grindstone, and half of an SB-250 grindstone. The SJ stone I have is still 240-245 mm. So, I figure getting 10 years or so from a stone isn't too bad.
Rich
Rich,
I'm still trying to figure this out: "Except for plane blades & chisels". If the stone grinding surface is true to the USB, why would it matter if these are not true to the side of the stone (rest of the world)? I see it the same as leveling a lathe, where leveling puts the ways square and parallel to the spindle axis (and it then cuts a true cylinder), regardless of how these relate to the rest of the world, ie, levelness to the surface on which the lathe rests.
I get it about the need to return a stone to being flat, after causing it become not so.
I'll take your comments on stone use on faith. I'm too novice yet to have sense of how long it takes to wear out a stone. I've unfortunately had too much else going on to use the Tormek as much as I'd like and have only had it for a few months.
Rick
Rick,
With my longtime consuming hobby interest in machine shop technology, I think I partially understand your machinist thinking. Let me take you backstage with my thinking.
A decision from over forty years ago illustrates my thinking. I was purchasing an enlarger for my photographic darkroom. I debated whether or not to spend fifty dollars more to get stabilized voltage. I did not think I had a voltage fluctuation problem, however, having stabilized voltage would eliminate any potential voltage problems. I spent the extra fifty bucks for peace of mind.
That thought process is still with me. While not all tools may require a true grinding wheel, having the grinding routinely trued will effectively eliminate problems associated with the wheel being out of true. Things like routinely and skillfully truing the grinding wheel, becoming fluent with the stone grader; and keeping the water trough clean all help reduce the number of potential problems.
Call me overcautious; that's how I think.
Ken
I'd say we think and behave similarly. I usually buy higher end tools and equipment when I can afford them, and sometimes when I can't really afford them. Bit of curse, but I don't try very hard to break it.
Rick
Rick,
What I'm saying about chisels & plane blades is this : they are held by a jig like the SE-76 or -77. This jig rides on the USB and moves only laterally. So, if the USB is not exactly parallel to the wheel's surface, the chisel or plane blade will be sharpened so that the edge is not exactly 90 degrees to the blade's side.
This can happen easily due to two things :
- the grindstone truing happens from the vertical position, and I sharpen those blades from the horizontal position. This change will certainly introduce some level of error, though it will be small.
- even when using the same position, just moving the USB in or out will introduce some error as the machine does not ensure perfect alignment of the USB arms, and this will also certainly introduce some level of error, though it will also be small. (Ensuring perfect alignment would require a significant enhancement to the machine's cost!)
In the world of machining, this is a big deal. But, I don't know how much this will matter unless you're a far better woodworking expert than I.
Kind regards,
Rich
Rich,
I do get what you are saying about chisels and plane blades not turning out square if there is a lateral slope/angle of the stone surface and the USB is square (or close to it) with the side of the stone. I was trying to make the case that if the USB was sloped the same as the grinding surface of the stone, they would turn out square. This is based on an assumption that if the stone were trued using the USB and the tool grinding are both done from the vertical position. You said you do your grinding from the horizontal, so I do get that it would make a difference there. So, why not do the truing from the same horizontal position at which you do your grinding.
This whole discussion just gave me a brilliant idea (we'll see about that). ;D My implied assumption above is that the USB is positioned consistently because the screw forces the USB against the back of the hole. As Rich points out, that is not as consistent as it needs to be for his purposes. So, what if the holes in the case where the USB mounts were the same as the "paatented" ;) holes in the jigs that mounts the jigs so securely on the USB? That out-of-round shape would be powerful at forcing the USB to lock down in exactly the same alignment every time. Think about it.
Rick
Rick,
It's early morning and I don't want to risk waking my wife on one of the few mornings when she has the chance to sleep later. So, I will answer your reply without the benefit of looking at my TT-50. I don't know if your idea of using the patented Torlock would work or not, however, I would give it an award for clever thinking. I have a high regard for the clever thinking of good machinists. Keep up the good work!
I don't know how much tolerance sharpening needs for different operations. I have never seen a blueprint specifying either a tolerance range of a minimum surface smoothness. I suspect they don't exist. Considering how often planes are used skew; both planes and chisels are intentionally ground skew; and that almost all bench planes made for over a century have lateral adjustment, I suspect that being "dead square" is not a high priority.
A game changer for me was reading the book, Gaging and Inspection. This book goes back to the need to quickly train thousands of skilled factory workers during World War II. It made me aware of controlling the variables I could in order to lessen the impact of those I could not control. Your use of your precision square is an example of this. Checking with a precision square takes no more time than using just a relatively square tool. Your ground edges are consistently more square for the choice.
I look at using the truing tool as a two axis graph. The horizontal X axis is time in use. The vertical Y axis is truenessof the grinding wheel. As we use the wheel it gradually becomes untrue. Tormek tells us that this amount of untrueness accelerates as the wheel becomes increasingly out of true. Our graph line is a descending slope. It can be a continuous line if we do not true the wheel. Or, the line can resemble saw teeth with regular light truing. Tormek tells us a wheel infrequently trued will wear faster than a regularly trued wheel. I have not verified this. However, if we convert the lines to average trueness, the average for the regularly trued line which never dips below a certain point will be substantially higher than the occasionally or never trued line average.
That is a controllable gremlin. Other gremlins are not so easily controllable.
I think the same principle applies to sharpening. Hand cutting dovetails, I can feel when the chisel becomes dull. It still cuts, but with more effort. Why keep cutting if a quick trip to the Tormek will restore optimum performance?
I am all for practices or improvements in our tools which tighten tolerances in a practical manner.
Ken
Ken,
I found two versions of the book, one dated 1951 and another 1987. The first had a single author, the latter three.
I've been working on CAD drawings for the motorization of the Truing Tool (attached). The PDF file has the entire assembly at the beginning and end. In between is each piece sequenced as it might be assembled. I'm at relatives for Christmas and didn't bring anything but the motor so my representation of the Truing Tool is very generalized. I'll get specific with it after I return home. After that I'll add dimensions on the individual piece drawings and then work can begin.
Pretty simple construction. I believe it could be done with a drill, a tap and a hacksaw. Drill press would be very handy as would a belt or disk sander to clean up the sawn edges. Material should be aluminum. I will use extruded box aluminum because it has square/sharp corners rather than the curved inner corner of angle stock. I have several different sizes of the box alum. and if I'm lucky, I can simplify this design by cutting off just one side to yield a three sided bracket and making the shaft mount of the knob chuck longer or shorter to suit.
Rick
Rick.
I look forward to learning more about your project.
Enjoy the holidays with your family; that is special time.
Ken
Here is a revised version, based on use of the box angle aluminum for the motor mount. Only two parts to fabricate, the motor mount and the knob chuck. I am pretty sure I have 2" wide box extrusion. Also, I forgot that the knob chuck requires a metal lathe, so construction isn't quite as easy as I thought. It would be possible to secure the motor shaft to the knob using parts that don't require a lathe.
I'm leaving the earlier version posted for those who don't have access to the box alum.
Rick
@Rick K - noted on name. Wow! Was not expecting that you'd be working on CAD drawings. (I'm excited!). If there's something that I can lend to this/help - please let me know. (Not sure what I can provide, but interested in helping if possible).
@Ken S - Despite the cost of the stones, I see those as purely consumable and one shouldn't be overly concerned with it's depletion. If truing happens to remove more than the sharpening, but ensures consistent angle - I'm fine with replacement. Granted, don't want it to be yearly, unless I'm doing enough sharpening to account for it. ;). I don't have any inhibition about truing it repeatedly and regularly. I think the first few times is more about getting used to/comfortable with some of the odd noises and vibrations that come with it's use. Those were [arguably] the most disconcerting the first few rounds with each type of stone.
I'm in the same camp (as well) as Rick K and Ken S in terms of things - overbuilt/peace of mind to ensure that things are optimal.
Justme,
One statistic I have not seen (it would vary quite a bit) is the cost of a replacement grinding wheel compared with the revenue produced by the consumed grinding wheel. We could compare the cost of ink and toner compared with the number of documents and photos consumed. We could compare the cost of a brake job with the number of trips to work, the kids or grandkids to school and family vacations.
I would expect the loss efficiency to improve with experience.
I have never thought that using a Starrett Satin Chrome scale as overkill; it is just pleasant.
Ken
Quote from: RickKrung on December 24, 2017, 05:30:00 PM
I would hold my square on the side of the stone and look at the surface of the stone.
Do this immediately after truing. If the surface is not square to the side then the horizontal portion of the US is not parallel to the axis of rotation of the grindstone. This might be okay if they are indeed not parallel, as long as they lie in a plane. But if they don't, that is, if they are askew, then you are definitely in trouble. Tormek won't comment on this issue, as far as I know. There was a chap here a couple years ago unable to get his chisel ends square and I believe this must have been his problem. Tormek replaced his machine.
The mounts that hold the two upright legs of the US have undergone a redesign when the T7 was replaced with the T8 (and likewise when the T3 was replaced with the T4 before that). They are now cast into the housing.
QuoteAnd then I wonder... What difference does it make... ? I've read about how the stone not being true has caused problems. I don't get it.
When the grindstone is out of round, you will definitely notice it. And unless you true right away the problem gets a lot worse a lot faster. Waiting too long means you'll have to remove a lot of material to get it round again. That's the real waste.
Herman states, quite correctly, that the mounts that hold the two upright legs of the universal support (commonly called the sleeves) are now cast into the top. This is only part of the story. All four sleeves are part of the single top casting, and they are also machined. They are aligned to a very high degree of accuracy, and that accuracy will not change. They are also machined slightly out of round for easier insertion of the support bar. This advance first appeared with the T4. Not only did it increase accuracy, the zinc top acts as a radiator to solve the overheating problem which had plagued the all plastic T3 housing. For practical purposes, the overheating problem was the housing, not the motor. The T4 corrected that. In my experience, the operator needs a rest long before the T4.
With the T8, over the long run, the single piece cast and machined zinc top may prove a more significant advance than the new water trough. (In my opinion, the redesigned feet which do not fall off are a welcome advance as well.) I do not believe many of these improvements were available when Tormek began in the 1970s.
Concerning the machine which was replaced a couple years ago, I believe that Tormek replaced that machine more for customer relation reasons than product problems. The problem occurred during the extended Scandanavian vacation period, and apparently there was also a shortage of trained troubleshooters in the UK who could be dispatched to work with the customer. I believe a proper training session with the customer would have prevented the problem.
Ken
Quote from: Ken S on December 27, 2017, 06:42:05 AM
Concerning the machine which was replaced a couple years ago, I believe that Tormek replaced that machine more for customer relation reasons than product problems. The problem occurred during the extended Scandanavian vacation period, and apparently there was also a shortage of trained troubleshooters in the UK who could be dispatched to work with the customer. I believe a proper training session with the customer would have prevented the problem.
IIRC his problems disappeared when the machine was replaced.
I wonder what would have happened if they weren't on vacation? I wasn't aware that trained troubleshooters are dispatched when there's no shortage.
I've had some time to work on the design of a motorized Truing Tool. CAD drawings are attached below. I spent a lot of time trying to work with a piece of U shaped box channel but the space on the side of the TT around the knob is just too confined. When I went to just an "L" shaped bracket for the motor mount, the design got real simple and even easier to make.
(https://forum.tormek.com/index.php?action=dlattach;topic=3339.0;attach=1529)
Also, when I got home, I could not find the 1/8" wall thickness box channel that I know I had before my move a year and a half ago, so I had to use what I had, which is 0.202" wall thickness. I like it better too. More rigid. I have not figured out exactly how I'm going to attach the knob chuck to the knob. I'm thinking with some drive pins, maybe. I'd like to come up with something that will break free when (not "if") the screw reached the end of its travel and I haven't switched off the motor. Limit switched would be good, so maybe I'll give that a go after getting this thing built.
Rick
Here are some photos of the first stage of fabrication on the motorization of the truing tool. My layout skills are a bit rusty, so I had to enlarge the holes to get the motor mounted and the bracket square on the TT. I believe it will require further enlarging of the motor mount holes and the bracket holes so the motor/mount can float and find its own center on the knob.
(https://forum.tormek.com/index.php?action=dlattach;topic=3339.0;attach=1531)
(https://forum.tormek.com/index.php?action=dlattach;topic=3339.0;attach=1533)
(https://forum.tormek.com/index.php?action=dlattach;topic=3339.0;attach=1535)
I'm still thrashing about trying to figure out how to connect the motor shaft to the knob. I'd like to drill a hole in the center and thread it to insert a screw of some sort and lock it with a nut. My concern is being able to adequately find the center of the knob.
I have figured out how to hold the TT for drilling.
(https://forum.tormek.com/index.php?action=dlattach;topic=3339.0;attach=1537)
Rick
Quote from: RickKrung on January 03, 2018, 10:19:25 PM
I'm still thrashing about trying to figure out how to connect the motor shaft to the knob. I'd like to drill a hole in the center and thread it to insert a screw of some sort and lock it with a nut. My concern is being able to adequately find the center of the knob.
Rick
Issue solved. I got the knob off of the TT screw. The knob mounts on the shaft via a threaded insert. M6x1.
(https://forum.tormek.com/index.php?action=dlattach;topic=3339.0;attach=1539)
There is about one turn of thread exposed, which is enough to get an M6x1 screw locked in place as a drive shaft for the motor. Now all I have to do is make a sleeve to fit over the motor shaft and thread the other end.
(https://forum.tormek.com/index.php?action=dlattach;topic=3339.0;attach=1541)
I have an M6x1 tap, so I should be truing via motor control very soon.
Rick
Quote from: RickKrung on January 03, 2018, 11:27:10 PM
Issue solved. I got the knob off of the TT screw. The knob mounts on the shaft via a threaded insert. M6x1.
Issue NOT solved. I cut down an M6 screw and machined a sleeve to mount it all up. Used a couple nuts to lock the screw in place.
(https://forum.tormek.com/index.php?action=dlattach;topic=3339.0;attach=1543)
There is huge wobble in the assembly. I tried taking a video of it, but it was massively large and I won't post it. I think the wobble is due to too few threads engaged between the screw and TT shaft. If I can get the brass threaded/press on fitting off of the TT shaft, I might have a chance at getting things lined up. Otherwise, I'll see if I can press on a length of delrin to serve as the connection between the motor and TT shaft.
If you look at the photo, you may notice I've added the zip-ties, ala Wootz, to steady the cross travel. Those ties are impinging on the added motor mount bracket, so I'll have to shorten the bracket. I'll also have to shorten the screws that mount the motor mount as the do-hickie that holds the diamond tip will impinge on the screws sticking out underneath.
This is all part of the design/implement/discover issues/redesign/reimplement/repeat... process that I enjoy so much about making things.
With this motor, I get a traverse time of 24 sec. at 100% power on the train controller. 60 sec. traverse time at 25% setting and 100 sec. traverse time at 20% setting.
Rick
Quote from: RickKrung on January 04, 2018, 01:26:22 AM
I think the wobble is due to too few threads engaged between the screw and TT shaft. If I can get the brass threaded/press on fitting off of the TT shaft, I might have a chance at getting things lined up.
Yup, that is the issue. I tried getting the threaded fitting off the motor end of the shaft, but the other end came off first.
(https://forum.tormek.com/index.php?action=dlattach;topic=3339.0;attach=1545)
After getting the intended fitting off and putting the threaded sleeve on it and checking runout with it in the lathe, there was less than 0.010" runout.
(https://forum.tormek.com/index.php?action=dlattach;topic=3339.0;attach=1547)
I will modify the design/assembly to rely on this method of connecting the TT shaft to the motor shaft. I'm hoping this will work satisfactorily.
Rick
Quote from: RickKrung on January 04, 2018, 02:06:15 AM
After getting the intended fitting off and putting the threaded sleeve on it and checking runout with it in the lathe, there was less than 0.010" runout.
Apparently not good enough. Still too much wobble to bolt it all down snuggly.
(https://forum.tormek.com/index.php?action=dlattach;topic=3339.0;attach=1549)
It would work as is, with not all the screws snugged up, but I'll pursue this some more to see if it can be resolved. I ordered some M10x1.5 SS threaded rod and will turn the motor end to mate with the motor shaft. I also ordered an M6x1 threading die to be able to put that on the free end to get that knob back on.
If that all doesn't do it, I'll probably just use it not snugged down. I believe it would work just fine.
Rick
I have gone back to hand turning the Truing Tool.
After trying motorized version on my black stone, it left those angular wavy lines about a third of the width in from the outer edge. I think without the dampening effect of the hands on the TT and USB, it is too free to vibrate. I tried holding it while it was running and going as slow as possible, but I could not prevent the waves from forming until I disassemble the TT from motor, reinstalled the knob and trued the wheel by hand.
It was fun trying.
Rick
Misalignment of the shafts can be fixed by a flexible coupling (simple as a piece of tubing, or custom made things) or you could have a wheel on the motor and then drive the shaft or knob with it. Kind of like how the grindstone is driven by a wheel.
If you can remove vibration you can determine if it's the vibration or something else causing it.
Quote from: RickKrung on January 04, 2018, 06:08:59 AM
(https://forum.tormek.com/index.php?action=dlattach;topic=3339.0;attach=1549)
I LOVE that !! And thank you for the pictures. I wasn't following the CAD drawings.
Rich
Quote from: Hlokk on January 05, 2018, 04:08:14 PM
Misalignment of the shafts can be fixed by a flexible coupling (simple as a piece of tubing, or custom made things) or you could have a wheel on the motor and then drive the shaft or knob with it. Kind of like how the grindstone is driven by a wheel.
If you can remove vibration you can determine if it's the vibration or something else causing it.
Yes, I have a flexible coupling coming from McMaster-Carr. I'll give it another try once it arrives. I also have some SS M10x1.5 threaded rod coming that I'll use to make a replacement TT screw to get away from having to attache the motor/coupling on the existing M6 threads. It would also help if I got my knee mill back together and running so I could be a little more accurate when drilling holes, etc.
Rick
That looks absolutely awesome!
RE: "wobble", almost makes one wonder if a bit of re-design shouldn't happen:
- move drive screw to a more "centered" position, enabling:
- use of ball-bearings (logical "front" and "back") to ensure that movement of the truing tip can only be "side to side".
- move to Rick's design (motorized + speed control) and micro switches at each end to enable "auto-reversing" of the motor to true in "multi-pass" mode.
In looking at your zip ties - went ahead, doing same, and attempted to re-true my SJ-250. The "more bound" (less movement/wobble) made a substantial improvement in the results. Had a portion that was "wavy" from previous truing attempt(s). A good portion of that was removed. Suspect that a couple more passes (removing barely topical amount) will completely clear that issue.
The balance of the stone's surface (majority of width) came out far better than previous. If you look at the right hand 20%, you'll see the uneven cuts into the stone (see attached image). Suspect that this may have been a result of the truing tip being able to 'bounce' off the stone due to "wobble" (movement space, albeit small - but present). The zip tie effect appears to hold the tip at a fixed distance. Thus, only removing at a specific depth and preventing it from being able to "dip" down into the stone. On an SG-250, likely not an issue. However on the much softer SJ-250 - huge difference.
Have to wonder how many people end up inadvertently applying "downward" pressure, because of hand weight or "resting" of the hand (possibly added limb weight) onto the truing tool - also impacting the result(s).
Quote from: RickKrung on January 06, 2018, 01:05:14 AM
Quote from: Hlokk on January 05, 2018, 04:08:14 PM
Misalignment of the shafts can be fixed by a flexible coupling (simple as a piece of tubing, or custom made things) or you could have a wheel on the motor and then drive the shaft or knob with it. Kind of like how the grindstone is driven by a wheel.
If you can remove vibration you can determine if it's the vibration or something else causing it.
Yes, I have a flexible coupling coming from McMaster-Carr. I'll give it another try once it arrives. I also have some SS M10x1.5 threaded rod coming that I'll use to make a replacement TT screw to get away from having to attache the motor/coupling on the existing M6 threads. It would also help if I got my knee mill back together and running so I could be a little more accurate when drilling holes, etc.
Rick
Rick,
Will you post a parts list with costs & where you got them ?
Kind regards,
Rich
Quote from: RichColvin on March 05, 2018, 04:00:01 AM
Rick,
Will you post a parts list with costs & where you got them ?
Kind regards,
Rich
Rich,
Stand by, please.
I have made substantial improvements to the Motorized Truing Tool since I last posted what you are referencing/asking about. I've been distracted by multiple other projects, several Tormek related and have not made the effort to update here.
Improvements include:
1) Ball bearings on both ends of the drive screw,
2) Replaced the stock drive screw with a 10mm threaded rod for turning precision bearing races on the ends for the ball bearings,
3) Drilled out and reamed screw carrier hole on one side of the Truing Tool frame to mm receive ball bearings (there was already a 10mm hole on the other end, but it was oversized, so I pulled a machinist trick to bring it back to a more precision usable condition),
3) Flexible drive coupling between motor and drive screw, and
4) Delrin insert into the diamond cutter carrier to stabilize movement to eliminated vibration causing it to travel in a more true and consistent path (replaces and improves upon the zip-ties).
I will attempt to get this posted soon. I'll have to go back through my records to get parts and sources, but can do that.
After making these improvements, I am re-thinking the hard-coupling drive in favor of timing belts. Much simpler and easier for folks with less machining capabilities. I have it in mind to try to make the re-designed timing belt version using very simple parts and tools to make it more universally accessible.
More later,
Rick
Okay, here goes. We'll see how far I get tonight.
When I last left this project, the motor was misaligned and could not be secured. There was vibration in the tool as it traversed, resulting in diagonal grooves toward the outer edge. I had installed the two zip-ties through the diamond tool carrier previously and that helped with keeping the diamond tip from dancing around, at least to an extend (read more on this later). I had given up on it in that condition and had gone back to hand truing.
I ordered and received ball bearings, 10mm stainless steel threaded rod, a 10mm reamer and a mis-alignment tolerant coupling. I also got my vertical mill set up and running, including the three-axis DRO, which I cannot live without now.
I started with machining the 10mm threaded rod to form journals for mounting the bearings and 6mm dia. stubs for mounting the drive components and bushings.
(https://forum.tormek.com/index.php?action=dlattach;topic=3339.0;attach=1933)
Once the journals were turned, I reamed out one side of the Truing Tool frame to receive the 10mm OD ball bearings. One side already had a 10mm hole, through which the stock 10mm threaded shaft passed as part of assembly. It was oversized, however, and the bearing would wobble. Could not go to all this trouble and have that. So, I took a sharp carbide scribe and dimpled the inside diameter where the bearing would mount. Fit snugly after that.
(https://forum.tormek.com/index.php?action=dlattach;topic=3339.0;attach=1921)
Here are all the shaft, bearings and other parts for mounting the shaft in the TT frame. One half of the mis-alignment tolerant coupler is visible on the far right.
(https://forum.tormek.com/index.php?action=dlattach;topic=3339.0;attach=1923)
The stock steel box tube that carries the diamond truing tip, that is driven across the TT by the 10mm threaded shaft is quite sloppy on the threads. The only threads in the two sides of the box are very minimal width and a fairly loose fit to the threads. To correct for this, I machined a piece of black delrin to fit snugly width-wise within the steel box tube, but with room to move vertically to allow for imprecision in placing the hole in the delrin, relative to the threaded hole in the steel box tube. I then drilled a hole through it where the drive screw crosses, using Letter Drill "W", which is 0.386" (9.80mm) but as with all drills, drills larger. The final hole is a snug but slip fit to a 0.388" (9.86mm) plug gage. The threaded rod I used measures 0.389" (9.88mm) for which a 0.389" plug gage is a very tight fit. This is exactly what I wanted, so that it reduces play as much as possible. It might be better if the delrin was also threaded, but I'm not sure. This procedure could be replicated fairly closely with metric drills, as there are sets in 0.1mm increments, from 6 to 10mm.
This delrin part fits quite snugly over the threads and virtually eliminates all wobble and play.
(https://forum.tormek.com/index.php?action=dlattach;topic=3339.0;attach=1935)
The box tube rides smoothly across the TT frame, on the ball bearing raced drive screw (this is only a temporary fix, as the delrin will wear as the screw turns in it. More on this later).
Also required was drilling an access hole for the diamond tip part and the 12mm set screw that holds it in place, as well as a clearance hole towards the rear for the USB. Note that this latter hole is oval in the steel box tube, but may not need nearly so much ovaling with the delrin insert, but I matched the oval hole in the steel tube. Parts shown, including one half of the coupling.
(https://forum.tormek.com/index.php?action=dlattach;topic=3339.0;attach=1925)
Here is the assembly, with the diamond tip dampening delrin insert, drive coupling and the retainer bushing on the other end. This assembly is tight, no wobble, just smooth travel.
(https://forum.tormek.com/index.php?action=dlattach;topic=3339.0;attach=1927)
I have visions of replacing the steel box tube and delrin insert with a fully machined, solid brass block, with all the appropriate features, but that is for the next phase. The fully threaded brass block would be a snug but smooth fit over the threads, and a slot would be cut across the threads and an adjusting screw placed so the block threads could be tightened over the shaft threads as the block wears. This is how it is done on machine tool linear motion screws.
At this point, you'd think I'd have a photo showing this improved version mounted on the T8, but somehow that got missed. Best I can do is to show a short (5 sec.) video of it in action, during what turned out to be a four minute traverse time on the final pass. First time or two, the wheel was not in full contact with the stone.
https://vimeo.com/258565704
I was truly impressed with the result. This SB stone had not looked this good since it was new. First shot shows the entire surface, second a closer up shot of the part of the wheel that was in the best focus.
(https://forum.tormek.com/index.php?action=dlattach;topic=3339.0;attach=1929)
(https://forum.tormek.com/index.php?action=dlattach;topic=3339.0;attach=1931)
As this stands now, I consider it a success and I will use it for truing all three of my grindstones. Modification I may make to this design are the solid brass diamond tip block, as discussed above and limit switches.
As mentioned earlier, I do have thoughts about how to simplify the design by converting it to timing belts, largely in part to get away from the hard drive line connection requiring the mis-alignment coupling. Timing belts might even aid in preventing damage if the motor were left on too long and jammed the diamond block against the end of the travel.
I envision mounting the drive motor lower, between the two USB uprights with timing pulleys on and extended TT shaft and drive motor shaft. I also hope to be able to design it using angle aluminum that anyone can buy at hardware stores, hacksawing parts to size and drilling holes using a hand drill. There will need to be some way of securing the drive motor to the USB to maintain position to keep adequate tension on the timing belt. It doesn't take much, and the two applications where I've used them before, they seem too loose, but they work great.
Rick
P.S. Forgot to mention, this design definitely needs limit switches. If left to drive all the way to the end of the the travel, it binds up really badly and something is going break. It would be nice to find reversing limit switches, but I'm not sure what to look for. It would need to turn off the DC current for the one direction (at the very least) and hopefully, switch the + & - leads to run the motor in the opposite direction. Would that be SPDT (single pole, double throw) variety of limit switch?
Your work never fails to impress!!! 👍 👍
I'm very impressed. Well Done.
Quote from: RickKrung on March 05, 2018, 07:38:02 AM
...snip...
At this point, you'd think I'd have a photo showing this improved version mounted on the T8, but somehow that got missed. Best I can do is to show a short (5 sec.) video of it in action, during what turned out to be a four minute traverse time on the final pass. First time or two, the wheel was not in full contact with the stone.
https://vimeo.com/258565704
I was truly impressed with the result.
...snip...
Nothing new to report, just and updated video, showing a full cycle of truing (over and back) using the motorized mod. Travel time is about 60 seconds each way, which is faster than previously shown and used, but it provides a sense of how it works without belaboring the viewing.
https://vimeo.com/270241192
Rick
Quote from: RickKrung on May 17, 2018, 06:19:09 PM
Nothing new to report, just and updated video, showing a full cycle of truing (over and back) using the motorized mod. Travel time is about 60 seconds each way, which is faster than previously shown and used, but it provides a sense of how it works without belaboring the viewing.
https://vimeo.com/270241192
Rick
That's pretty cool. 👍 👍