Topics

There is not much info on our forum about whether to or how to sharpen a ceramic knife.  I did a search and didn't find much.  I have the full complement of grinding wheels, SG, SB, SJ, and all three diamond wheels.  I assume it would be best to use the diamonds, but has anyone actually done this and if so, how did it go? 

I'm back at a farmers market today and last week one customer said they would be bringing in two ceramic knives for me to sharpen.  I realize it is last minute and I have not do my homework, but if anyone has any suggestions (other than telling him to come back when I know more, which I am likely to do at this point), I would greatly appreciate it. 

Thanks,

Rick

...snip...
Rick,

On a practical level, would the chip in your photo cause any grinding problem?

Ken

Ken asked the above question about a chip in the edge of my SJ stone.  It doesn't seem to matter with the SJ stone, but I am concerned about similar but smaller chips in the edge of my DF-250 diamond wheel. 

There are two chips, one larger.  I hear a ticking sound as at least one passes under a knife, I assume the larger.  I'm not happy with these photos (from my phone) as they are not as in focus as I'd like.  I'm waiting for my digital camera to charge to try to get some using the macro feature.  If that fails, I'll try my disecting microscope. 

Under 60X hand scope, the larger one appears to be an area missing some of the diamond coating.  The shiny part near the bottom left (trailing edge) appears to be that coating (or something) smashed/smeared against the lower boundary of the chip.  It appears elevated, which would be consistent with the ticking noise. 


Here is the second chip.  This one seems to be missing the chunk of coating that had been there, but nothing on the trailing edge.  There are a numbe of shiny specks spread over the surface of this part of the DF-250 wheel and they appear to be smashed down peaks of coating.  I cannot tell if they contain diamond which has also been smashed down.


I have not sent this in to Tormek Support for their appraisal, but plan on doing that.  I've been really careful with these diamond wheels, to keep them from bumping into each other or anything else.  During a session, I store them strung on a 12mm stainless rod that spans beyond the width of the plastic milk crate that I use for transporting them and my other stuff.  For transport, they are laid flat with a clean hand towel laid flat over each one.  At no time do any of the wheels touch another. 

I don't even know what question to ask.  I guess I'm just putting it out there to see what others think. 

Rick

Two things converged to make this happen.  First, I recently set up my 8" Rikon "slow speed" bench grinder with two BGM-100 USB supports.  Second, I came home from a farmers market sharpening day with four plane blades to sharpen.  I had set the BGMs up for use with the Frontal Vertical Base (FVB) which provides UP/Down (vertical) USB adjustment as well as In/Out (horizontal).  So far I had used it for rough grinding of knife bevels and drill bit facets. 

The plane blades were pretty rough, having been bought at garage sales, although that doesn't mean we don't beat up our own.  I wanted to do the rough grinding of the plane blades on the Rikon as I thought it would be faster and save some wear on the Tormek wheels.  I initially set up one of the blades in the Square Edge Jig (SE-77) and then set up the USB/FVB on the fine wheel side (right) and proceeded to grind the blade.  No problem, as the standard way to set up a blade in the SE-77 on the Tormek is in the vertical USB for edge leading grinding.  That works for the BGM USB on the right side of the dry grinder. 




It does not, however, work for the coarse wheel (left side), due to the sliders hitting the USB mounting posts.  In order to use the SE-77 on the left side BGM/USB, I had to turn the plane blade around in the jig so the edge projected out the "back side".  I had not anticipated this as there was no mention of anything like it in the manual, but it is exactly what would have to be done to used it on the horizontal USB on the Tormek if one wanted to grind edge trailing.  And it works beautifully as the SE-77 is essentially symmetrical in that regard.  I set up one of the larger blades that had a lot more grinding to do, due to rounded corners and nicks and proceeded to grind on the coarse wheel. 




This worked very well, except that it took a long time, I think because I was taking a lot of care to prevent heat build up on the blade, so I took limited, light passes and dipped the blade in cool water whenever it was the least bit uncomfortable to grip and squeeze the edge.  I wonder if it wouldn't have been just as fast on the coarse diamond wheel (DC-250) as there would not have been the pauses to check for heat.  Nonetheless, I am happy with using the dry grinder for the plane blades and will continue its use.  (BTW, I thought the finish on the dry grinder blades was quite good, even from the coarse side and prior to becoming a Tormek user, I would have been quite happy to use them that way.)

Rick

Is possible though the use of a small pin vise (or similar). 


I just put a four-facet point on an 0.92" (2.33mm) drill bit that is the pilot drill for a screw head countersinking tool.  The point really isn't that pretty but it works, whereas if not sharpened it might have been tossed. 




Positioning the flutes was tricky, but this drill bit had an exceptionally wide web so maybe more normal (thinner web) drills will be easier.  I used the DF diamond wheel and the material really came off the drill bit fast, so very slow and gradual feed and a gently touch was necessary.  I may try it with the DE wheel to see what that is like.  I think the grind finish from the DE wheel would better suit such small drills anyway. 

I didn't like the knurling on the barrel of the pin vise I have and it's collets don't allow full length insertion, so I will try a so called "Precision Pin Vise" from MicroMark.  Holds down to 0.039" drills and I don't think I want to be trying anything smaller. 


Rick

...snip...
On the T8, the platform is a little over 45mm away from the left edge of the grinding wheel.  I think this is too close as the DBS sliding platform tends to tilt as it extends out over thin air on the left side of the fixed platform.  I find that I have to pay special attention to preventing this tilting as it can mess up the facet grinds. 

...snip... 
Rick

I commented previously about the position of the DBS-22 Base Plate being too far to the right on the USB, allowing for tilting of the drill bit holder at the left extreme of travel during grinding.  Even being aware of it and trying to not allow it to tilt, the pressure of trying to hold the bit holder firmly down while sliding inevitably led to tilting.  I decided to take care of that today.  I cut and milled out a section of the left side of the USB sleeve from the Base Plate.




It allows the Base Plate to be positioned about 32mm further to the left.


Providing full support for the drill bit holder when the drill point has reached the left edge of the grinding wheel.  I haven't used it yet, but feel confident that I'll be able to slide comfortably without risk of tilting any more. 

Rick

I know there has been discussion of sharpening axes previously.  I just had not done much, only one until today.  Today, at the local farmers market, a fellow brought in a hatchet and a double bladed axe.  The hatchet was easy to do using the axe jig and I did it at the market.  Got it sharp enough to push cut telephone book paper, using the DC and DF diamond wheels and leather honing wheel. 

The double bladed axe was a different matter.  The axe jig doesn't work.  So, I figured I'd have to rig up a platform or find a what to jig it for use on the USB.  The latter is what I did.  I took a deep cabinet clamp and secured it at the center of the double blade, both laterally and longitudinally.


I used the laser to indicate the LOC and pivoted mostly, only lifting slightly as it reached the corners.  It also push cuts phone book paper, using only the DC/DF/LW. 


Rick

I tried out some drill bit sharpening last night with my set of three Tormek diamond wheels.  I approached it all cautiously, not wanting to put too much pressure on the diamond grits.  I tried to let the weight of the DBS-22 drill bit holder jig dictate the pressure, but it wasn't that easy.  Holding the jig and sliding it back and forth took some grip, on both the bit holder and the sliding plate.  Grinding went pretty fast and took less grinding to achieve the desired results than the SB or SG stones did previously.  I took some pix in hopes of sharing how it all went, but the photos were really crappy (out of focus), so I bagged them and will try again and do a better job with the photos. 

I found the contact behavior of the drill bit on the grinding wheels curious.  As I traversed the drill jig back and forth, the drill bit made contact with the grinding wheel at the edges first and more than at the middle.  At first, this variable contact was more on the right side and not at all at the middle or left, so I thought it was misalignment of the USB.  But, as I did more, it became apparent that it really was just at the sides, as though the middle was "lower" than the sides.  I take that to mean the wheel is not flat all the way across.  At least not as flat as the stones were after truing, as there was full contact all the way across with both the SB and SG previously.  I have wondered if there was something about the way I was holding/using the jig, but as mentioned, this didn't happen with the stones. 

Also, the wheel seemed to not be concentric in rotation.  The drill bit would contact on one part of the wheel and not on another as the wheel rotated.  I have not repositioned the wheel to see if the inconsistent contact went away and I have not run an indicator on any of the diamond wheels - I'm not thrilled about the notion of grinding a flat spot on my indicator needle.  There are ways of putting something sacrificial between the grind wheel and indicator, but I have not done that yet either, to see just how much these amount to.  When/if I do so, I think I'll try spinning the wheels on the shaft, without them being locked in place by the nut, to see if it is in the wheel or maybe due to the miniscule gap between the wheel hole and the shaft.  I have not attempted to measure the wheel hole, but I can to that fairly precisely. 

I am not sure there is anything wrong with the wheels.  I am just noticing a behavior that I didn't expect.  I'm not sure how much difference it makes to grinding anything.  It sure doesn't seem to matter to knives.  I do wonder about planer blades, however, as they need to be very uniform and precise.  What I can say is very qualitative: it has the "feel" that something is not right, so the experience of using the diamond wheels is inferior to the stones. 

Also, the wheels are not exactly the same diameter.  The DC and DF wheels are very close, 250.47mm for the DC and 250.45mm for the DF.  The DE wheel is 250.12mm.  I don't think it matters to most uses.  For knives, the difference in wheel diameter makes only 0.1º angle difference.  The only thing about drill bit sharpening was that when it came time to use the DE wheel, the jig had to be run down a tiny bit to get contact.  I'm not suggesting there is anything wrong with the wheels, just observing.

Rick

(P.S. How is that for "devilish details? 

Setup instructions (distances/dimensions) for the BGM-100 with bench grinders are NOT for use with the drill bit jig, DBS-22. 

I recently set up two BGM-100s on both sides of an 8" bench grinder following the instructions that come with the BGMs.  https://forum.tormek.com/index.php?topic=3737.0  My intended use at the time was for knife sharpening, which I have largely abandoned due to the heat generated. 




Setting up the BGMs using the standard guidelines provided in the manual results in the USB being entirely too low.  This is understandable, as the BGM manual makes no mention of using the setup for drill bit sharpening.  Instead, it is all about wood turning tools and the like. 


The USB needed to be set another 41mm higher than the standard BGM setup.  A Frontal Vertical Based (FVB) allows for setting the USB higher, as needed, but the USB is still too far away from the grinding wheel, at least with my current FVB.  Making the body of the FVB narrower would rectify this and allow use of the DBS-22 without further modification of the BGM height setup.  I was already thinking of how to streamline the FVB and make a couple more for this setup, now I have more justification. 


An additional aspect of the standard BGM setup is how close the inner USB support rod is to the grinding wheel.  For both the left (coarse) and right (fine) grinding wheels, the DBS platform and slider are too close to the grinding wheel, compared to the horizontal USB setup on the T8. 

On the T8, the platform is a little over 45mm away from the left edge of the grinding wheel.  I think this is too close as the DBS sliding platform tends to tilt as it extends out over thin air on the left side of the fixed platform.  I find that I have to pay special attention to preventing this tilting as it can mess up the facet grinds. 


On the left BGM, there is even less room, about 25mm, so I am certain there would be a problem with tilting. 


On the right BGM there is a lot of the platform to the left, but only about 25mm on the right.  That may not be a problem as the majority of the weight of the slider and drill bit holder jig is on the left. 


In short, I think the BGMs need to be further away, to the left and right, from the grinding wheels for adequate support of the sliding platform/drill bit holder.  I'll report back once I figure out how far seems good.  I'll also be moving the support blocks back enough to get the USB close enough to the wheels to use my current FVB and be able to do some rough grinding of drill bits. 

Rick

There has been discussion off and on about adapting Norton 3X (or any other standard grinding wheel) for use on the water cooled, low RPM Tormek.  I've found it very useful and do not want to be without it, even though I have a full complement of Tormek grinding wheels.  To use the Norton wheels, I had to make adapters to fit the 1" arbor hole to the Tormek 12mm shaft.  I know Ken used the plastic bushings that came with the wheels but drilled out some PVC pipe to 12mm to make that final step.  I recall he used a number of fender washers as flanges also.

I've gone off looking for a larger grinding stone (2"x10") for which I'll likely have to make more adapers. 

But...  in that search, I came across some adapters that may be of interest to anyone looking to use the Norton 3X wheels:
https://www.woodturnerscatalog.com/p/97/6196/Raptor-R3X-Grinding-Wheel-Bushing-2-Piece-Set



If the 5/8" bushings were used, there would still need to be that final step of drilling out some PVC pipe, but that should be doable by most. 

Rick

After the farmers market work I've been doing, I thought it time to true the wheels.  SB and SG went fine.  SJ wheel is curious.  There is a very loud "crunching" or grinding sound as the truing tool traverses, seeming uncharacteristic for what should be a very fine stone. 
https://vimeo.com/291399304

Also, there are quite a few curious little bumps on the surface. The only thing that makes sense to me is these must be soft spots that flex under the truing diamond tip and the pop up when the pressure is off. 


I'll finish this using the grading stone and then a 1000 grit diamond plate and see what, if anything remains.  I think they won't matter to the function of the SJ wheel, I just find them curious. 

Rick

It still offends my good sense (or maybe not so "good") that there is so much loss/spillage of the ACC-laced water coolant when using the diamond wheels.  So, I wondered and have started trying out using just plain water for general work with the diamond wheels and then at the end of the session, replacing the water with ACC-laced water to "rinse" the wheels with the corrosion preventing solution and running the wheels a bit.  That has taken the form of when sharpening the last knife and going thru all the diamond wheels, or, after it is all over, cycling the wheels through the solution before setting out to dry. 

Makes me happier.  That spilled water doesn't bother me.  Waiting to see if it results in any rusting. 

Thoughts/comments?  I wonder if Tormek will notice and comment. 

Rick

Finally got around to setting up a new 8" Rikon low speed grinder with dual BGM-100 USB supports today.  I bought the grinder last May and the BGMs earlier than that, all before I had decided to get the diamond grinding wheels.  Recently, while using the coarse diamond wheel I was still wanting more aggressive and faster metal removal for creating basic bevels on seriously dull knives and repairs.  I dabbled with the 1x30" belt sander that I have but blew up a belt on a knife, separating the belt at the seam.

I'm doing knife sharpening at the Farmers Market in my tiny home town of Halfway, OR for the first time tomorrow.  It could be a tough crowd, cow-pokes and hunters, all of whom think they know how to sharpen things (many have said so when I have mentioned my sharpening activities).  So, maybe not related, but I was really wanting to have that more aggressive capability tomorrow, as I expect to see some seriously dull knives. 

So, with the belt sander not an option I want to trot out in public, I got serious today with the Rikon and BGMs.  I was a bit surprised at how easy it was, once I got into it. Turned out all I needed was a couple blocks of 4x4s for the BGM mounting supports, aligned them per the instructions and Viola!


I used the HanJig angle setting tool I made recently to set the grinding angle.  Worked quite well as the 8" grinding wheels are within the tool's envelope. 


My first usage was on a cheap Santoku 5" slicer that had a short section of unbeveled blade at the handle.  Not really a bolster, just an unground and unsharpened section.  I ground that to match the rest of the blade and put a nice clean 16º bevel on it.  I worked it until I got a burr along the entire edge.  I did notice the knife getting hot and at that "non-bolster" area, it turned color a bit, indicating it got too hot.  So, it will take some practice with a gentle touch to ensure the apexes don't get overheated, but I really like how it worked.  It has a better feel than the belt sander. 


I will be very happy taking that knife to any of my grindstones for final bevel grinding and honing/deburring.  The whole process will be much faster and with fewer grinding wheel changes.

Rick

Below are several threads from the BESS Exchange on the finer points of burr and wire edge removal necessary to achieve sharper and more durable apexes on our knives, that I have found very interesting and helpful.  I have not yet implemented any but the techniques proffered by Knife Grinders (Wootz on our Tormek forum) in the last one is what I find most informative and helpful and I do plan/hope to follow. 

Link posted by Knife Grinders (Wootz on our Tormek forum) on the BESS Exhange
http://bessex.com/forum/showthread.php?tid=373

Article by Larrin Thomas referenced/linked in KG's post above
https://knifesteelnerds.com/2018/08/27/what-is-edge-stability/

CATRA Testing on Edge Retention Embedded Within the Above Thomas Article
https://knifesteelnerds.com/2018/06/18/maximizing-edge-retention/

Wire Edge Removal Discussion on Bess Exchange Initiated by KG
http://bessex.com/forum/showthread.php?tid=372

Rick

This is being ported from another thread so as to not "hijack" that thread.
https://forum.tormek.com/index.php?topic=2639.165#lastPost

(This is rather lengthy and is getting away from the topic of this thread, so I'm going to port this over to a new thread, once this is posted here and will insert the new thread link here.)
https://forum.tormek.com/index.php?topic=3725.0

The Farmer's Market went really well yesterday.  I only sharpened five knives, four paying customers and a freebie for my daughter (a strange, unequal trapezoidal shaped veggie harvester [the knife, not my daughter, although she is a veggie harvester]).  I charged $5 per blade.  The low volume was to be expected as the availability of knife sharpening had only been announced the day before on the Market's Facebook page. 

The market is open 3-6:30pm Weds. and had never before had anyone sharpening anything.  It was very dead for the first hour, even for the other vendors (one berries, two veggies, one bakery and one fruit).  It really picked up for the other vendors after that.  While I only sharpened five knives at the market, there was a fair bit of interest by "passer-by"s and several asked "Oh, will you be here next week".  My booth was at one end, next to the berries, so someone had to actually notice me over there and take an interest. One woman brought with her two knives her husband had given to her to get sharpened.  Two others went home and brought back a knife.  I also came home with five knives and a pair of scissors to sharpen.  One of those five knives is quite interesting and will be very much a challenge, but more on that later and may deserve a thread of its own.  That knife was among three others in a large canvas folding wrap like chef's use for storing and transporting their knives.

The two brought by the woman were, an ancient bone-handled "Buck"-like folding knife and an even more ancient "traditional" hunting knife with a leather ring handle (I didn't take any photos).  Both were literally as dull as butter knives.  The folding knife scored an impressively dull 1940 BESS.  The hunting knife was extremely convex and thick, almost like an axe and had a "fuller" down it's length.  It was even duller than the folding knife, so much so, I didn't measure it. 

One of the "went home for" knives was a longer Farberware knife that was in decent shape, sharpened quickly and turned out my sharpest edge of the day from the basic treatment (see below).  The last knife was a shorter "custom" hunting knife the guy got from his grandfather, who received it as a gift from the maker, but it supposedly never had and edge on it.  They guy had tried to sharpen it, to no avail, but at least didn't really damage it. 

Generally, for all the other knives, I used the SB stone and/or DF250, ceramic rod (CR)(thanks CB), leather wheel (LW) and SharpPAD (SP).  The hunting knife seemed like it was going to take the most work, so I started with the DF wheel and finished as above.  The custom knife was so beautiful I wanted to do a nicer job, so I started with the DF250 wheel (DF) and used the SJ stone between between the SB and LW.  Specific combinations are listed below.

The angles on the folding, hunting and custom knives did not "measure" using my laser gionometer, so I had to "hunt" for the angles using black marker and my jigs.  I think they didn't measure because they were so dull and rounded that they diffused the laser beam too widely.  I started with the shallowest angle that seemed right and set up the Tormek using whatever jig that was close.  If that was too shallow, adjusted with the next jig until I got as good a match
as I could and then sharpened.  They all ended up at 16º or 18º.

NUMBERS

I only measured three of the knives before sharpening, but for all the following measurements were taken during sharpening:  After grinding and after stropping: Three measurements were taken, near the base, in the middle and near the tip and averaged.  All measurements were taken using an Edge On Up PT50A which measures the force required to severe a standardized, certified media, in grams. 

Cabbage Lopper
SB/CR/HW        SP
    250               222

Bone Handle Folding  Before sharpening: 1940 gf
DF/CR/HW        SP
    365               215

Leather Handle
DF/SB/CR/HW  SP
    217              190

Farberware
SB/CR/HW       SP
    204              157

Custom
DF/SB/SJ/HW  SP
    289             169

For all knives, I did the paper push cut demonstration.  All still had a few "catches" except the Farberware.  But, all of the customers were VERY happy with the results and the lady that brought to two for her husband tipped an extra $5.

All in all, I think a very successful day and first attempt at a Farmer's Market.  It was fun, but I think when it gets busier in subsequent weeks it will become less so and more like work.  I anticipate "finishing" with the big event of it moving to a new location in mid-Sept. 

Rick

P.S. Oh Yikes, my daughter posted a photo on their Facebook page:
https://www.facebook.com/bakercityfarmersmarketor/?fb_dtsg_ag=AdzAgL5j1Mh_USnFWtnGynL79khBe9C3II3yOksiIL9tJQ%3AAdzJcYwf4Sg3kNDOC9ST1-vKzf7JZz5PPqoxky3Apy83nQ

Couple photos, after the fact.

Veggie Lopper


Chef's Knives (although the curved one is a bit out of character it seems to me).


Rick

I am porting this from the thread about a you tube video showing use of the small knife jig with woodcarving tools. 
https://forum.tormek.com/index.php?topic=3654.0#lastPost

But, with my post below, I feel the context may become diverted and do not want to hijack that thread.

I was a bit underwhelmed when he didn't correct the misalignment of the knife in the small knife jig.  I've only used mine a time or two and found the need to work the handle in the jig a bit to get the blade better aligned.  Interesting trick to back the stop a turn or two to change the angle to get the bevel widths the same.  He did not speak to how well centered the apex was after that, however. 

I was surprised to see him use the fine side of the stone grader to clean the SJ wheel.  I'm trying to remember if that is a recommended practice or if anyone does that.  I'd think it a bit coarse and would, over time, take off enough material to change the wheel diameter.  I have wondered a bit about the Nagura stone that I use and how it cleans the black stuff without take much if any of the stone away. 

I've been struggling, in my head, about the use of multiple Tormeks versus changing wheels.  I use only two wheels at the moment, the SB and SJ.  I change wheels on my single Tormek.  Soon (I hope) I will have three wheels (diamond) which will also need changing on a single Tormek.  I assume I will still use the SJ wheel after the diamond wheels, and while two diamond wheels may do it for some blades, I am sure there will be some that need more significant work and will require the use of the coarse diamond wheel (360), which could mean up to four wheel changes for a single blade.  Suddenly, a second Tormek is becoming more attractive.  I've also recently acquired a buffing machine and a paper wheel, so that would very likely change the mix at the finishing stage. 

I've only ever used a sharpening service once, at a local pub and supermarket, but I don't recall that he used but one wheel and then the leather honing wheel.  Since getting a Tormek and following discussions about setting the USB height for different angled, I seem to recall the guy did not change the USB for different knives, meaning he would have changed the bevel angles on some knives. But that raises the question in my mind how he could do that so easily using only one wheel and not seeming to take a long time on any knife. 

At home, I work at my own pace, so wheel changes are not much of an issue.  However, my daughter manages a small farmer's market in the nearest "big" city, Baker City, OR. which, at 9720 pop., is by no means big. They have only about six tables (vendors) and appear to be struggling.  I was asked a couple months ago, before the marked opened, by my daughter if I wanted to set up a sharpening booth.  At the time, it was an emphatic "NO".  I am reconsidering that now, and that raises the issue of wheel changes in a different way: cycle time.

I think this could warrant it's own thread, so as to not bury it here or high-jack this thread, so I will start a new thread using my post here. 

Rick

One question is, is there a break point between using multiple wheels, involving time consuming wheel changes, on a single Tormek versus using multiple Tormeks, eliminating or reducing wheel changes when doing volume sharpening, for example at a Farmer's Market or similar venue? 

Rick

Have any of you looked closely at the diamonds in the "Diamond Cutting Tip".  I hadn't, but I did notice a while back that there seemed to be one standing quite a bit taller than any others.  I didn't explore that then and have since used it to true my SB stone. 

The discussion of truing the SJ stone caused me to look more closely at how much my SJ stone was out of round.  About 0.6mm (248.78mm max., 248.72mm min.).  I was thinking of truing it but was concerned that there might be that one diamond standing too tall and what that might do the the SJ stone.  So I looked at it under hand magnification (60X) (https://www.amazon.com/KINGMAS-Microscope-Magnifying-Jewelry-Magnifier/dp/B00AQAANDS). 

I was a little surprised, 1) that they seemed so large, 2) that they were so dark and last 3), that they were clustered along one edge.  You can see the scour lines in the copper base indicating which way the stone was going over the face of the cutting tip. 


The way the cutting tip was mounted in the truing tool, that row of diamonds were in line with the rotation of the stone (parallel), so only one side of the cutting tip was doing the work.  I thought that was not so good, so I loosened the screw holding it in place and rotated it 90º so the row was perpendicular.  Now the entire front side of the cutting tip with all the diamonds would be doing the work more evenly.  It did not seem to matter to the SB stone, but I feel the truing tool will do a better job on the SJ stone with the diamonds oriented this way. 

Rick

Reading some of the posts in the SJ wheel discussion made me wonder, what does it matter if the stone is out of round a little bit?  At least for hand held jigs/operations. 

Using Wootz's applet, I checked to see what the angle change is for a 1mm eccentricity in the diameter (that is 0.5mm at the stone/edge interface).  For a stone at 245mm, 139mm projection and 16º starting angle and USB height of 169.12mm.  Changing the stone diameter to 244 and adjusting the angle until the USB height was nearly identical (USB 169.13mm), the angle changed to 16.3º. 

Assuming lateral travel is slow enough to expose an edge to the full excursion of the diameter at least once along the entire length, what does that angle difference mean to the sharpened edge?  A slight flattening of the concavity.  Less sharpening action at the apex.  Since we sharpen until there is a burr, the latter would mean it would take a little longer to raise that burr.  For production sharpeners, I can see that mattering, but to the more casual sharpener, like me, what does it matter? 

Rick

I bought a planer (DeWalt 735) and started discussing it on the General Questions Forum.  That led to discussing sharpening the "disposable" blades, so I think it should be continued here. 

Essentially, we determined that the planer has disposable blades, 7/8" wide, that should fit in the planer blade jig and there should be enough stock on the blades to take a sharpening or two, as long as they aren't nicked or badly dull.  I would appreciate the thoughts of anyone with more experience and especially with this type of blade. 

https://forum.tormek.com/index.php?topic=3643.msg23837#msg23837

Rick

I bought a planer this week (DeWalt 735), to make wood whatever thickness I want for making jigsaw puzzles for my granddaughter, using the scroll saw (DeWalt 788) I bought two weeks ago.  Guess I'll be buying a planer blade sharpening jig.  There isn't much that can be done with dull scroll saw blades, however. 

Rick

I've read and heard that "light pressure" should be used with the new diamond wheels and to "let the diamonds do the work". 

Well, I am wondering just what does that mean "light pressure".  That is very qualitative, as what is light pressure to one may be heavy pressure to another.

Can "light pressure" be characterized in some standardized manner, or quantitatively, such that every user can correctly interpret it and use the appropriate pressure on the wheels.  Does it constitute just the pressure of the weight of the jig and tool being sharpened?  Just a light touch with a finger or two, or a very light "lift" for tools that do not contact the wheel by their own weight? 

My knife edge sharpening testing instrument (Edge On Up's PT50#)(http://www.edgeonup.com/index.html)  measures in grams of force required to sever a standardized media and sharpness is rated according to an accepted standard (BESS scale of sharpness)(http://www.edgeonup.com/eou_new_2016_008.htm).  (My PT50 happens to the the "A" model which measures in 1 gram increments.  The others are 5 and 20 grams.)

I wonder if grams of force could be a standard way to characterize the necessary pressure for the diamond wheels. 

I wonder if the PT50A could be rigged in such a way as to measure the force (grams) applied by just a tool/jig resting on it, and then with a finger of pressure, etc.?

I am asking sincerely, as I am spending a bunch of money on the wheels and sure as heck do not want to abuse them and dull them prematurely. 

Rick