Author Topic: DC-250 aka Burrzilla  (Read 1704 times)

Offline Cyrano

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DC-250 aka Burrzilla
« on: July 01, 2018, 02:48:41 am »
This is a burr from the SG-250 graded to 1000, used on a fixed-blade Mora:



The SG-250 graded to 220 yields this burr:



The DC-250 causes this burrpocalypse:



I can often get reasonable edges by using the SG-250 at 220 grit, and following it immediately with the leather honing wheel. I was hoping to use the DC-250 in a similar fashion, but so far the poor leather wheel hasn't been able to deal with Burrmageddon.

Offline Ken S

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Re: DC-250 aka Burrzilla
« Reply #1 on: July 01, 2018, 02:09:38 pm »
Cyrano,

You have a very good start on your research. I like both your objective and your method.

One of the major differences I have noticed between the Tormek design staff and most of the sharpening designers is that most of the sharpening world is still in the high speed dry grinding mode. I would say that most of us on the forum who have used a Tormek for some time have also made the mental mode switch to low speed cool Tormek thinking.

To stay current, we must develop another thought mode. We must be able to switch from the "Original Tormek Grinding Wheels" mode to the Tormek Diamond Grinding Wheels" mode. In some ways that will be a more difficult switch. We do not have the guiding material to help us with the transition. The latest edition of the handbook was just posted on the Tormek website. The handbook was very well written by Torgny Jansson many years ago. It is a thorough guide to learning how to use the Tormek with the SuperGrind (SG) grinding wheel. I happen to like the handbook. It reminds me of the Leica Manual and the Graphic Graflex Manual from my film photography days. I have collected various editions of all of them for reference. The handbook has not been updated for the blackstone or the Japanese stone, which were added eight years ago. I will be happily surprised if the handbook is really updated to Tormek Diamond thinking.

Our standard knife, chisel, scissors, and turning tools videos were also produced in the SuperGrind era by Jeff Farris. Again, they are well done instruction for the SG "Original Tormek" grinding wheel.

Back to you, Cyrano. I hope you will add the DF-250 and DE-250 to your study. In learning to think in Tormek Diamond, the 600 grit DWF-200 wheel for the T2 is Tormek's original diamond wheel for knives. That would fit with the modern practice of using the stone grader to make the SG wheel 600 grit.

I have heard a rumor that the DWC-200 was added to the T2 at the request of a major customer. For an old chisel guy like me, the DWC is a terrific wheel. For knife sharpening, I think we should give the Tormek design staff a fair hearing and give the DF-250 a thorough test. Diamond grits are sharper than aluminum oxide. I think starting with a coarse wheel for general knife sharpening is a holdover from earlier thought modes. Way back in the SuperGrind wheel only days, Jeff Farris generally omitted the coarsely graded grinding wheel from his knife sharpening routine.

Please continue your research; your work is interesting and informative.

Ken

Offline cbwx34

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Re: DC-250 aka Burrzilla
« Reply #2 on: July 01, 2018, 02:40:45 pm »
...
I can often get reasonable edges by using the SG-250 at 220 grit, and following it immediately with the leather honing wheel. I was hoping to use the DC-250 in a similar fashion, but so far the poor leather wheel hasn't been able to deal with Burrmageddon.

That's because it wan't designed to do that.

My philosophy is to be as "burr free" as possible, before using the leather wheel.  The leather should be to clean up and refine the edge... not to remove a large burr.

Try making a few very light alternating passes on the DC-250, to see if you can reduce the burr enough for the leather wheel to do it's job.  If you can't, consider an intermediate step, for example, a couple of controlled passes on a ceramic rod will remove a large burr.

Another alternative would be to use a more aggressive compound on (another) leather wheel ("another" is assuming you still want a fine compound for other jobs)... if you really want to use the leather wheel to remove the burr.
« Last Edit: July 01, 2018, 03:10:10 pm by cbwx34 »

Offline Ken S

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Re: DC-250 aka Burrzilla
« Reply #3 on: July 01, 2018, 03:48:58 pm »
I agree, with the exception that all should be made with a light touch with the diamond wheel. I would make the final pass with a VERY light pass.

Ken

ps I made similar tests with 80 and 180 grit CBN wheels with the Tormek. An 80 grit CBN wheel makes a formidable burr! I had BESS readings of 400 to 500 as is. Going directly to the leather wheel, which I do not recommend, lowered the BESS readings to under 200.

Offline cbwx34

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Re: DC-250 aka Burrzilla
« Reply #4 on: July 01, 2018, 04:45:24 pm »
I agree, with the exception that all should be made with a light touch with the diamond wheel. I would make the final pass with a VERY light pass.

Ken

I was actually going to put very light in bold.  :D

Offline Cyrano

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Re: DC-250 aka Burrzilla
« Reply #5 on: July 01, 2018, 09:52:13 pm »
I get the message: use the right tool for the job -- which in this case is not the leather honing wheel.

The burr you see from the DC-250 is the result of as light a pressure as I could manage: just the weight of the knife/jig, with minimal pressure to guide the blade over the wheel. While this was a very light pass, it was not a fast pass.

Offline Ken S

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Re: DC-250 aka Burrzilla
« Reply #6 on: July 01, 2018, 11:57:04 pm »
Cyrano,

You were using the right tool; you had just skipped the important middle steps. We all do that; I think it's human nature. We use instant "oatmeal" instead of taking the extra time to cook NcCann's Irish oatmeal. (Once you try the real stuff you will never be satisfied with instant.) When I worked with the CBN wheels, I was surprised with the fairly good quality of the chisel edges going directly from an 80 or 180 grit stone to the leather wheel. As a control, I sharpened an identical chisel with the traditional three step method. The BESS number was considerably better. I think it is good to know how to do quick and dirty. Sometimes that's what we need. Let's not forget how to get a really sharp edge.

Ken

Offline Ken S

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Re: DC-250 aka Burrzilla
« Reply #7 on: July 02, 2018, 02:52:49 pm »
In the video that Sharpco provided the link to in the knife section, the comment was made that comparing 320, 600, and 8000 grits, the results were marginally better with 600 grit. I don't know how significant this is, however, it is interesting.

Ken

Offline Ken S

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Re: DC-250 aka Burrzilla
« Reply #8 on: August 09, 2018, 09:41:12 pm »
I just reshapen and sharpene a turning skew using the T8 and DC-250 360 grit diamond wheel. Once the DC-250 did the heavy lifting, which did require a lot of time, work with the DF and DE went very quickly. After each step, the bevel scratches were noticeably decreased (by eye).

Since all three wheels have a continuous 250mm diameter, the platform jig was already set for the finer wheels. The EZYlock made quick work of the wheel changes.

Ken