Drill Doctor

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abunai

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Has anyone had any luck with the thing?????
I bought one a long time ago. Model 500.
Could never got it to work like had hoped it would.
Can never get it to give a decent relief angle.
Is there some trick to to it????
 
Comments and question about these have come up a number of times. Overall most folks like them. I had one of the older 500's and used it regularly. The wheel started to wear so instead of replacing the wheel, upgraded to a newer model that can do split points etc. They take a little practice to get the hang of it, but once you do, it;s the fastest and most accurate way I have found to sharpen bits.
 
I think for the money it does a terrific job, I can grind by hand but my eyes aren't what they used to be - so the DD helps a lot on the smaller bits.
It does take some practice to set the drill in the holder correctly, but once I figured that out, it's a breeze to get a sharp bit quickly.
 
I have a DD 400 (old model) and a 750. I haven't used the 750 yet but use the heck out of the 400. Very happy with the results. I still do small (≤1/8") ones by hand.

Bruce
 
One thing I don't fully understand is the relief angle or I think the lip angle? I'm talking about the the place you stick the collet where it grabs the bit and holds it in place while you tighten it down. It says 118° and there are two slots left or right of that center slot.

Also I have not had success in splitting the point. It works nice on one side then the other side the grind is down on the heel area.
 
I have reground several hundred or more drills on my DD750, and a couple hundred on my Craftsman jig before that. I have also played around a bit with Sellers and other commercial drill grinders. Also sharpened at least a couple hundred by hand. All of those methods work, and any can do an excellent job if you understand how drills work, how to adjust the various angles to fit the specific drill and application, and know what visual and measured end result you are looking for. Not trying to be condescending or anything, but you have to be smarter than the dumb machines, which have no idea of the diameter of the drill, helix angle, desired relief angles, or know what changing those parameters does to their performance on different materials. That requires some study. Here is just a start:
http://neme-s.org/2005 May Meeting/drills.pdf
 
I've had a 750 (classic) for going on 20 years. It did a fine job for about 10 years sharpening 50 or so bits per month. Later in it's life I started having trouble with relief angles. When I did use it I spent more time readjusting the bit for the proper angle than it would have taken to sharpen it by hand.

Now that the eyes aren't what they used to be I decided hand sharpening bits was too much of a PITA. A shop owner approached me earlier this year wanting to sell a Black Diamond drill grinder. We arrived at a mutually agreeable price so now anything from 1/8" to 3/4" (including all letter drills and number drills to #30) are sharpened using the new machine.

I am in the process of making bushings for #31 to #52 bits, and 1/16" to 7/64". The "new" machine doesn't have the attachment for spitting points, so I still use the Drill Doctor for that.

Here's are a couple pictures of the "new" machine.

IMG_0655.JPGIMG_0656.JPG
 
I have the 750 and it made sharp bits that wouldn't cut. I found I had to increase the relief angle on the settings to get them to cut.
 
I have a DD750 and have found that there are some bits that it will not sharpen properly. I think it is due to the twist part being different then normal. Otherwise I am happy with it.
 
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