Messages

I picked up an SJ stone and a second grading stone today at Woodcrafters in Portland, OR, USA.  Being a relative novice, and having just bought an SB stone, primarily for drill sharpening, I was going to wait on the SJ.  But I was killing time while my daughter and granddaughter were at a science and industry museum this morning and as I perused the Tormek rack, there it was, saying "take me home". 

So, now I'm paying more attention the the SJ threads and comments.  Where can I get the rust eraser and Nagura stone? 

Rick

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

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

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).   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

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,

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

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

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. 


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

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. 




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

Nice work, Rich. 

I have an SVD-186 its way to me.  I'll replicate most what you have done for mounting the rotary cutter.  One thing I noticed in your videos is there is a very slight up/down movement as you turn the wheel using the handle.  Did you examine the edge to see if there was any indication of differential sharpening due to this action? 

I am wondering about a way to motorize that rotation so as to avoid that up/down movement. I have a slow motion motor controlled by a hobby train controller, that I use for making bamboo fly rods.  I wonder if it couldn't be attached this jig to give uniform rotation. 

Rick

Hello everybody,

I'm having difficulty truing the SG-250 stone of my T8.

What I am observing is that there is a lot of resonance/vibration when truing the first (about half) part of the stone (from outside to inside).
The result is a wrinkled pattern on the first (outer) half of the stone, the second half has a smooth finish.
I'm lowering the TT-50 no more than one mark or digit and I'm completing the process in no less than 90 seconds.

What am I doing wrong?

I have attached a picture to illustrate what is happening.

Kind regards,

Gijs

Gijs,

I recently bought an SB-250 and excitedly put it on and set about truing it and got exactly the same thing, diagonal waves. 



I was going to post about it but figured out the problem.  I had not tightened the locking screw that clamps the jig securely to the USB.  As soon as I clamped it tight, the waves went away. 

Rick

I don't think any of that matters.  I believe it is simple physics.  I think the amount of water on the wheel is the result of the surface tension of water.  If the full width of the wheel contacts the water (and breaks the surface tension), as it exits contact with the water, the surface tension will cause the same amount of water to be carried up the wheel, regardless of how deeply the wheel was submerged in the water. 

If you want to reduce the amount of water on the wheel, I believe you would need to devise a controlled water application, similar to how coolant is applied to the cutter and work pieces on machine tools (flood coolant on lathes & mills but "flood" would not different, perhaps worse).  It may be as little as dripping water on the back side of the wheel without the wheel being submerged in a pool of water at all, or a small stream of water. I think the latter as without enough water, you lose the benefit/function of water on the wheel - cooling.

Rick

Replying to my own post...   Depth of submersion could make a difference, but again due to surface tension.  Water attached to the sides of the wheel would be carried up and add to the amount of water on the grinding surface.  But by how much? 

Rick

Good comments. From my unscientific viewpoint, I don't think the volume in the tray is what matters. I think what is important is the amount of arc of the grinding wheel which is submerged and bringing up water. I like to keep the flowing water to a minimum, so I keep the water level as low as possible.

Keep up the critical thinking.

Ken

I don't think any of that matters.  I believe it is simple physics.  I think the amount of water on the wheel is the result of the surface tension of water.  If the full width of the wheel contacts the water (and breaks the surface tension), as it exits contact with the water, the surface tension will cause the same amount of water to be carried up the wheel, regardless of how deeply the wheel was submerged in the water. 

If you want to reduce the amount of water on the wheel, I believe you would need to devise a controlled water application, similar to how coolant is applied to the cutter and work pieces on machine tools (flood coolant on lathes & mills but "flood" would not different, perhaps worse).  It may be as little as dripping water on the back side of the wheel without the wheel being submerged in a pool of water at all, or a small stream of water. I think the latter as without enough water, you lose the benefit/function of water on the wheel - cooling.

Rick

Rick,

This is definitely an issue for Tormek support. (support@tormek.se)

Ken

Thanks, that's what I have done.

Rick

The motor on my very new T8 has shut down on its own a few times today.  Several times, it did so within seconds of it being turned on and a couple other times, after it had been running for short time. Breaker has not tripped and there are no other signs of electrical issues. 

Rick