View Full Version : Drill Grinder, TDR
10-18-2008, 02:32 PM
I just aquired one of these TDR Drill Grinders, by Service Precision Grinding:
A couple of times in the past, I've had occassion to use one, and fell in love, that's why I snapped this up when I had the chance. However, I'm having trouble using it. Downloaded the manual, and it refreshed my memory as to how to line up the cutting edges of the drill with the "scribe mark" on the chuck. However, this machine's chuck is damaged (easy to do, with a slight mis-adjustment) and I can't see the scribe mark. I THINK I finally found evidence of it and aligning the drill bit appropiately gave me a drill that definitely cuts, but I'm still unsure if it's correct.
Does anyone have one of these things and can you tell me the correct angle of the little scribe mark?
10-18-2008, 03:54 PM
Ooh, I'm jealous. I too have lusted after one of those for some time. A friend has one and it does a wonderful job. I've got a Christen that could not only put a 6 facet cutting point on a human hair, it could split the point, but it only does up 1/4" max.
Alas, I can't help with your question as it is not here. But if you don't get anything before tomorrow, I'll probably be going down there and I'll try to get a pic and other info.
The scribed line runs left at bottom to right at top at 15º through the center of block with knob facing the right side looking at the end. I have a older model of the SRD grinder. Set cutting lip ahead of line and grind to line. Close block up set in mill take skim cut to clean end and scratch a new line
10-18-2008, 08:44 PM
I'll try putting a pencil line where you describe and see how it works. What I THINK I'm seeing of the original appears to be more like 90*, running corner-to-corner of the square hole in the chuck. If the line was originally where you describe, that's in an undamaged area, and there's no evidence of a scribe mark.
Will letcha know tomorrow.
Thanks for the tip!!
10-18-2008, 09:08 PM
My block is marked 15 degrees like Lane described.
10-19-2008, 09:41 AM
I marked the chuck at 15* and ground a bit accordingly. Although it really drills, it sure looks to have way too much relief, or positive cutting angle, or whatever you want to call it. Interestingly, aligning the bit's cutting edges with the corners of the square hole in the chuck really doesn't seem to rotate the bit all that much, but it does give significantly less relief. If I take a more-or-less fresh drill, it'll still grind quite a bit on the heel before getting to the cutting edge, but not nearly as much as at the 15* setting.
At any rate, the grinder sure does a nice job, I think better than my $150.00 Drill Doctor. And, it really isn't any harder to use.
The guy I bought it from told me, "I just don't use it, I grind my bits by hand". This is in a professional shop, too. Although I found that hard to believe, I wasn't about to argue.
Thanks again for the help!!
here is a idea that mite work. Take a new drill of sufficient size like 3/8 put in block but tighten only enough that you can still rotate it. and with out motor running slide in and out to wheel and rotate drill until it just feels like rock is touching both ends of wheel . tighten block and mark with pencil.
Lightly grind one edge and look at ,rotate one way are the other until it looks right Then grind other side and check . Remark block before taking drill out. Might get you real close.
10-19-2008, 01:16 PM
Good idea, thanks!
I did just what you suggested, and it worked great. The only thing that bothers me is that the cutting edge is lined up approximately 15* opposite from what you initially told me, IE: it's going down, left to right, clamping knob on the RH side.
Your initial suggestion put the line where I remember it from the other machines that I had used, but as I said, the cutting angle seems much too acute.
Even with this last setup, a 3/8" or 1/2" bit wants to grab a bit in aluminum, especially if it's enlarging an existing hole. Tried the 1/2" bit in steel w/o a pilot hole, and it drilled well.
I'm thinking of marking the chuck in some sort of semi-permanent manner, perhaps coat it with Dykem, then lightly scribe a line. Do some more bits and see how it works.