Scraper blade sharpening

[Mel]

Hello:

I have a Baldor-style tool grinder with a 360-grit Accu-Finish diamond wheel (table adjusted to -5 degrees). I'm curious if there would be much advantage in getting the slower-speed Accu-Finish grinder with the 600-grit wheel?

Mel

 

[Erik Brewster]

I''m not completely sure about this, but I think that a fast diamond wheel on carbide should be fine. A nominal speed of diamond on carbide is around 2500 sfm (1700 RPM @ 6") (http://www.ukam.com/diamond_tools.htm). If you do that on steel, you will have problems with "carbon will dissolve into the workpiece and lead to tool wear and work hardening" (http://www.ice-va.com/aboutDiamond.html), due to the heat speeding up the chemical reaction. It is my understanding that this only happens appreciably at high temps and running not at a low speed (300 rpm?). I don't have any concrete references confirming this, but there are lots of mentions to this in forums (and the Glendo style grinder exist to do exactly this).

And not directly related to your question, but I found this low speed grinder page in looking for references and thought it was neat - http://www.gadgetbuilder.com/GrindRLap.html

 

[Richard King]

Hello:

I have a Baldor-style tool grinder with a 360-grit Accu-Finish diamond wheel (table adjusted to -5 degrees). I'm curious if there would be much advantage in getting the slower-speed Accu-Finish grinder with the 600-grit wheel?

Mel

I am not sure what you bought. I use a wheel like this on a Baldor double end grinder with tilt tables. But I say a minimum of 250, I used to always order a 300 or 320 grit wheel.

http://www.ebay.com/itm/6-DIAMOND-P...694?pt=LH_DefaultDomain_0&hash=item3c9daed9ce

I see there is Glendo on Ebay now. I have one just like it Accu Finish 1 and I use a 600 grit wheel. You should check with Gleno as they sharpen scraper blades at the shows. They will know if there wheel will woork on a fast Baldor. Did you look at Bills post under the GA class. He found a cheap set up for cheap. Todd made one too. The blade should be tipped 5 degree. Mel look at the 3rd part of the DVD, it shows a Glendo. Rich

 

[Mel]

Thanks for your input guys.
Yes, I have a double-ended Baldor clone from HF (I scraped the table flat). I'm using a 360-grit Accu-Finish wheel which definitely works on the carbide Biax blades. I had to make larger holes in the wheel and re-tap the threads on the grinder plate to make it fit though.
I was just curious how much much a difference it would make to sharpen on the slow speed Accu-Finish (or Calamar) at slower speed and finer grit. I suppose it's the difference between grinding and honing the edge. I just don't have a good sense of how much of a real-world difference it will make when it comes to scraping. Maybe I'll just get one and try it out.

 

[Tommy Brooks]

Thanks for your input guys.
Yes, I have a double-ended Baldor clone from HF (I scraped the table flat). I'm using a 360-grit Accu-Finish wheel which definitely works on the carbide Biax blades. I had to make larger holes in the wheel and re-tap the threads on the grinder plate to make it fit though.
I was just curious how much much a difference it would make to sharpen on the slow speed Accu-Finish (or Calamar) at slower speed and finer grit. I suppose it's the difference between grinding and honing the edge. I just don't have a good sense of how much of a real-world difference it will make when it comes to scraping. Maybe I'll just get one and try it out.

I got a accu-finish for the GA scraping class, and it really did a great job on scraper blades. We had 10 students and most stayed 5 days. That's a lot of sharpening. For the class we used Richards 260 grit wheel. I am using a 600 grit wheel now and really like the finish. Have you considered a VFD
for your grinder?

 

[Mel]

I considered a VFD for this, but I've read that this will not work with a grinder motor like this. Another consideration would be to install a blank metal disk on other end of the grinder and put lapping compound on it.

Mel