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#11
General Tormek Questions / Re: Beginner Sharpening Proble...
Last post by Ken S - Yesterday at 01:46:01 AM
Rod,

You are making progress, not there yet, but going in the right direction. The grinding wheel graded coarse should do "the heavy lifting". Grading it fine should reduce, but not eliminate the scratches. This stage should not take much time. You don't mention using the leather honing wheel. That's where the real polishing happens. After the leather honing wheel, you should have very few scratches.

How do your chisels cut after you sharpen them?

Ken
#12
General Tormek Questions / Re: Beginner Sharpening Proble...
Last post by RodC - February 02, 2023, 06:14:09 PM
Here is an update on my Tormek sharpening experiences.
 
I can now do a pretty good job of doing the initial coarse grinding. I looked at the sharpening video that one of the members suggested (thanks!) where the Tormek rep spent some time discussing the use of the stone grader.  He mentioned using the edge of the coarse side instead of the face.  I now do this and the coarse grinding goes a lot faster.

My problem now is that the fine sharpening stage is slower than it should be.  I think I am prepping the stone with the grader correctly.  First I empty and refill the water bath (I am suspecting that floating coarse grit might otherwise contaminate the fine grinding).  Then I use the edge of the fine side of the grader, then switch to the face.  I probably do about 20-30 seconds of each, or about a minute total.  I feel the stone to check to see if it feels completely smooth.  Then proceed to sharpen.  I work at it for about 20 minutes and get so-so results.  I still have some scratches that I don't get out.

Things I have tried:
I added a magnet taped to the outside of the T-4 tray.  This does collect swarf.  Not sure if it actually helps with the problems I have been having.

I lighten up my pressure on the chisel towards the end of the coarse grinding.  The idea is to try to have less deep grooves in the chisel in preparation for the fine sharpening.

I am no longer sliding the chisel back and forth across the stone.  I am sharpening carving chisels and am using the SVS-38, and the manual says to NOT move the chisel.  This is because this jig does not have two points of contact with the USB like the SE-77.  IMHO it is too easy to slightly mis-align the chisel face if you move it around    I think this has helped somewhat.

Questions:
Do you think I am prepping the stone for fine sharpening correctly?

Are the fine sharpening results I am expecting realistic?  I am used to sharpening woodworking chisels on water stones with a Lee Valley or Lie Nielsen jig.  I am expecting the sharpening results to look similar to what a 1000 grit water stone produces.  That means a dull mirror-ish finish with no visible scratches.  I switched to the Tormek for carving chisels since they have double bevels, with each bevel about 11 degrees (about 22 degrees total bevel angle).  This is too shallow for the jigs I use with the waterstones.

Thanks in advance for any insights.
   
               
#13
Knife Sharpening / Re: Measurement Jigs for Usb h...
Last post by tgbto - February 02, 2023, 10:18:43 AM
You could have a sharp convex edge, where you'd have consistently ground a non-constant angle and still be very sharp, making up with technique what the jig lacks in precision.

I think there's a bit of a logical flaw in saying that as Woot'z creed to get sharp knives was angle consistency, then if it's sharp it must be consistent.

Also you could have ground a very precise angle and still left a bit of a burr so lower sharpness than someone whose angle would vary more but with better deburring.

To put it another way, it seems to me the equivalent of saying "To drive precisely you need properly inflated tires so if you compare two drivers on a racetrack changing tire pressure in between the two runs, the fastest one has the tire pressure closest to the optimum"

If you want to judge angle stability, the dispersion of a reflected laser will give some information. If you want to judge angle accuracy within .25°... Well good luck setting up the proper test environment in the first place.
#14
General Tormek Questions / Re: Where to purchase CrO2 pas...
Last post by TireguyfromMA - February 02, 2023, 08:17:38 AM
Yes, the green powder is a pure Cr2O3 pigment powder sold by art supply stores. This is the same product that Vadim uses in his video on How to make your own Cr2O3 paste.  Avg micron size is 0.3, corresponding to a 100K grit.

https://www.youtube.com/watch?v=BQ6GNRQmRHI
#15
Knife Sharpening / Re: Measurement Jigs for Usb h...
Last post by Sir Amwell - February 01, 2023, 10:04:59 PM
Maybe another way to gauge the consistency of angles using such a jig across formats ( eg from grinding wheel to leather honing wheel to felt wheel to paper wheels) where a protocol is being followed (eg one of Wootzs for a particular knife steel) would be the sharpness results. Sure you can test on a goniometer to within 0.25 of a degree but what will matter is the final sharpness results? If the jig doesn't allow for consistent and repeatable angles across formats then final sharpness will surely be compromised.
For me the proof of the pudding would be sharpness rather than what my goniometer is telling me.
Or am I missing something?
#16
Knife Sharpening / Re: Measurement Jigs for Usb h...
Last post by 3D Anvil - February 01, 2023, 08:11:52 PM
I can tell you that, using cbwx34's calculator, I am able to repeatably sharpen knives to within around .25° of the intended angle, confirmed by goniometer.  Maybe closer than that, but my goniometer isn't that accurate. 
#17
General Tormek Questions / Re: Where to purchase CrO2 pas...
Last post by 3D Anvil - February 01, 2023, 07:12:00 PM
Quote from: Ken S on January 31, 2023, 09:26:21 PM3D,

The Amazon listing for your product does not list a grit size. The green chromium sticks are commonly .5 micron. Although Wootz specified .25 micron, .5 seems very close. I suspect it would work well for the majority of the knives we sharpen, certainly for mine.

Ken

I think what Wootz was saying was that pure chromium oxide powder has an inherent grain size of .2-.5 microns, for an average grain size of around 0.35 microns, which is equivalent to a grit rating of about 100k. 

One thing to note about making your own emulsion is that that green powder is REALLY green and will stain anything it touches.  I guess artists use it to make paint colors.  If you didn't have a green thumb before making your mixture, you will after.   ;D
#18
Knife Sharpening / Re: Grinding software upgrade ...
Last post by cbwx34 - February 01, 2023, 02:44:56 PM
Quote from: Roger M. on February 01, 2023, 03:47:54 AMWhatever came along with iOS 16.2 (20C65) has unfortunately rendered both of the Knifegrinder apps unusable on iPhone, as they try to execute a forced update, and of course the apps are no longer in the app store.

I don't know what the Android situation is currently? ... perhaps the apps still work on Android?

Vadim's apps were revolutionary when they first appeared, I jumped right on board and downloaded his standard app, and later the front vertical base app ... Wootz was certainly a powerhouse in the sharpening world ... I miss his non-stop research into almost anything to do with knife sharpening!

Off now to check out the generic equivalents, no choice really!

I don't think the iOS update did anything... mine have continued to work thru the current 16.3 update, and I would be surprised if Apple "forced" an update on an app no longer in the store.  You will most likely lose the apps if you do a restore from backup, or upgrade to a new phone, since apps are no longer stored in a backup.

I checked the Google Play Store, and noticed that the FVB app was no longer was there (at least I couldn't find it), so I suspect the others may eventually disappear also.  (Both Apple and Google said last year that they would purge "abandoned" apps that met certain criteria.)

Although you probably already know, available options can be found HERE
#19
General Tormek Questions / Re: Is my kj-45 faulty?
Last post by Ken S - February 01, 2023, 12:55:20 PM
Rimu,

Your KJ-45 is not defective. The slight bow in the middle is an intentional design feature. Cabinetmakers often use the same principle to edge joint boards for glue joints. It is called a spring joint. When clamped, it allows a tighter fit. With the Tormek knife jigs, both the newer KJ jigs and the previous SVM jigs, it places the maximum clamping pressure to the ends of the clamp.

Ken
#20
General Tormek Questions / Re: Where to purchase CrO2 pas...
Last post by tgbto - February 01, 2023, 08:46:16 AM
Quote from: TireguyfromMA on January 31, 2023, 05:00:23 AMjust add a little bit of mineral oil to get the right consistency, then apply to your leather wheel or strop

If I'm not mistaken, I think Wootz advised linseed oil for leather and mineral oil for paper or felt.