dry wall knives

[Elden]

   A friend brought some dry wall knives to be sharpened ie squared up. It was on the barter system. He had given me some dirt for raised garden beds. These knives are used for mudding sheet rock. They have a 90° bevel angle and have a thin, flexible blade. The  entire edge must be straight. Far as I know, it is not a good Tormek candidate. If you can think of a good way, post it. A significant amount of metal has to be removed, approximately 1/4" (6.26mm). This is from the sides (1/8"or 3.13mm from each side) as well as the working edge.
   The wood working 4" (101.6mm) belt sander did the job admirably in a reasonable amount of time with no over heating of the tool. Little 15 to 30 second breaks allowed it to cool quickly. On that thickness of blade, your hands make a well working heat sink.

[Herman Trivilino]

Elden, I would recommend the SVD-110 Tool Rest, used as Tormek recommends for cabinet scrapers.

http://tormek.com/international/en/grinding-jigs/

In both the case of the cabinet scraper and the drywall knife, a straight edge is what's desired.

You could also free hand it using the US in the vertical position.

By the way, drywall knives don't normally require any grinding. It sounds as though these may have been abused.

[Elden]

Actually no abuse. Normal wear from much use. The corners become rounded off when originally were they were square. Check out any dry wall knife that has been used for a quite a while. One person that I know that has mudded for a living, stated that he threw away his 5" knife after each new house job. The other fellow didn't agree with that thinking.

[Ken S]

Eldon,

Place your universal support bar, the long leg, in the horizontal sleeve nearest the grinding wheel. The two short legs should be sticking out across the face of the grinding wheel horizontally. You will want a piece of one by wood laying across the two short legs across the side of the grinding wheel. You can either clamp the one by directly to the support bar legs or put either a tool rest, the bottom of a scissors jig or an XB-100 (if you happen to have one laying around like I do).

You want a flat platform traversing the side of the grinding wheel. Make sure the support bar is horizontal so that the platform will be square with the grinding wheel.

If this is unclear, let me know and I will email you a couple ptotographs.

Ken

[Elden]

   Thanks Herman and Ken.

   Herman, I watched the DVD-110 Tool Rest video and that does certainly look like a possibility, if the blade is long enough to allow a stop (guide) to be clamped parallel to the edge. It would form a "depth stop" to ensure a straight finished edge. Those that have an inserted blade would possibly have a functionally, working stop in place.

   Ken, I am fairly sure I understand what you are saying. If you would send an email.

   One thing that may be a problem is chatter forming due the thickness (thinness) of the blade and the 90° bevel. Hopefully the underlying support will be close enough to the wheel to eliminate that problem.

[Ken S]

Eldon, I will try to send you some photos this weekend. If you are able to post them on the forum, I would appreciate that.

Ken

[Herman Trivilino]

Elden, did you try clamping the knife in a bench vise and taking a flat file to it? I would think the steel should be soft as it's not designed to hold an edge.

[Elden]

That is a good idea for a light touch up, Herman. I know the owner said that the  12" knife had a tiny knick in it causing it to leave a little line. However, it was LONG gone by the time the corners were brought back to square.

[Ken S]

Eldon, I emailed the photos to you. They should make my idea clear, better than words.

Ken

[Elden]

   For the sake of clarity at a later date, Ken' s pictures are posted in the Tormek general questions section of the forum. See:

http://forum.tormek.com/index.php?topic=2519.0