Tuned my Ulmia mitre saw

De-tempering steel for drilling holes

Bill Houghton, Sebastopol, CA

>The method I was taught, which works best with a drill press, is to chuck a plain steel rod in the drilling tool, clamp the sawblade firmly down so that the place you want the hole is centered, and then act as if you're trying to drill a hole through the metal, until you see it darken from the heat. This removes the temper in that localized area.

I imagine it would also work with a breast drill, but I would want some way to keep the rod from wandering -- perhaps a hole drilled in a piece of wood and clamped over the intended hole location (just make sure you don't emulate the Boy Scouts and start a fire this way!).

Congratulations, and a

Wiley Horne--Glendora CA

>nice saw, too! Here is a picture of the Ulmia miter saw, for those not familiar with it.

Christian, how did you go about making a hole in the hardened steel?

Wiley

Re: Congratulations, and a

Christian Aufreiter, Austria

>Thanks for the tip, Bill.

As for the hole I tried different drill bits. I needed a 6 mm and a 9 mm hole at each end of the blade. The only drill bit which worked quite well had 4 mm dia. I set the drill at the lowest speed and dropped some oil on the blade and drill bit. I was a pain, took quite a long time and I wasn't satisfied with the results. Finally I used files and suceeded. It might have worked better with a new high quality bit. But those HSS and Karat bits I had had seen lots of use during the past so they weren't perfectly sharp (apart from the 4 mm bit which was almost new).

Regards,

Christian

Re: Putting holes in saw steel

William R. Duffield, on the Cohansey

>There is a much better way to do this.

I don't try to drill holes in saw steel. I use a pin punch. You can find sets of these in any diameter you need from Enco, Grizzly, etc. These have a round cross section, and a ground flat, hardened tip. Sets cost from about $6 (Chinese) to $25 (Starrett) to $29 (Proto, extra long), or you might find what you need at a flea market, or even at your local TrueValue.

For example, there are several sets on Page 52 of the Enco catalog. If you click on this link, it will download a PDF file of the pertinent page of their catalog. Pin Punches

I find a scrap of hard maple and clamp it in the vise with a flat, end grain surface up, set the steel on top, put the head of the punch on top of the steel, and strike it with a hammer. It leaves a neat round slug embedded in the maple, and a neat round hole in the steel. You can remove the burr with a stone if you want.

Today's valuable lesson

Bill Houghton, Sebastopol, CA

>Thanks, Sir W. I never realized that a regular pin punch was strong enough to punch a hole in saw steel.

Re: Today's valuable lesson

William R. Duffield, on the Cohansey

>What makes it work is the hardness (and therefore the brittleness) of the saw steel, and the sharp edge on the punch.

BTW, this one was taught to me by Todd Hughes, either on this forum or on BPNH, which many may not find surprising.

If you are less than careful with the direction of your hammer blow, you can easily shatter the pin punch shaft, especially if it is a cheap Eastern knockoff. While you may think this knowledge would be classified as a DAMHIKT, I consider it an opportunity. I chucked the broken tool steel end in the lathe and ground it to a point with my angle grinder (it was a little too hard for

a file). Right now, I'm mulling over my choices of wood for the handle, and this evening, I will turn it into an awl. Number One Son needed one, and took the "family heirloom" home with him last week.