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Drill Doctor

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abunai

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#1
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????
 

coherent

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#3
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.
 

34_40

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#4
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.
 

BGHansen

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#5
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
 

ddickey

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#6
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.
 

Bob Korves

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#7
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
 

projectnut

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#8
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.JPG IMG_0656.JPG
 

jim18655

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#9
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.
 

tweinke

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#10
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.
 

abunai

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#11
Went back a reread the manual.
It says to move the setting for the alignment setting from split point, counter clock wise, to standard point.
I'll try it and see what happens.
 

benmychree

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#12
I had a drill doctor and a Oliver of Adrian drill grinder, used the doctor for small drills and the Oliver for drills up to 3"; it was worn, but it would still do better than by hand; nowadays, I mostly grind them by hand, but can still go to my old shop and use the machines; my doctor did the split point and worked well, although I did have to adjust the setting fixture to get enough clearance for free cutting.
 

westerner

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#13
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 had one for several years. I find this myself. The bit is sharp, but does not cut well for the first two or three attempts. I assume, that until I get the relief angle a bit "relieved", it rubs a bit. After that, it cuts better than I can do myself, at least for the smaller stuff. I like the thing, I use it regularly, but I recognize I can make a "sharper" bit. NOT a more even, or long lasting, bit. Just a "sharper" one.
 

Bob Korves

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#14
I have had one for several years. I find this myself. The bit is sharp, but does not cut well for the first two or three attempts. I assume, that until I get the relief angle a bit "relieved", it rubs a bit. After that, it cuts better than I can do myself, at least for the smaller stuff. I like the thing, I use it regularly, but I recognize I can make a "sharper" bit. NOT a more even, or long lasting, bit. Just a "sharper" one.
Look at the drill at intervals while grinding it. Leaving it in the holder, pull it out and look at the drill carefully, under good light, with corrective lenses if necessary. The chisel point should typically be at about 45-50 degrees to the cutting edges, depending on what you are going to use it for. Larger angle, gives less back relief, better for harder materials and shallower feed rate. Smaller angle, more back relief, better for softer materials and deeper feed rate. Also look at the side of the drill, at the angle of the back relief is visible where cutting edges meets the side of the drill. Less angle gives slower cut, more angle gives a more aggressive cut, but less strength. Look at the sharpening tool manual and at the link in post #7. Get a drill point gage so you can check for equal length cutting edges and equal and desired angles of cutting edges to shank.
 

jdedmon91

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#15
I have had one for several years. I find this myself. The bit is sharp, but does not cut well for the first two or three attempts. I assume, that until I get the relief angle a bit "relieved", it rubs a bit. After that, it cuts better than I can do myself, at least for the smaller stuff. I like the thing, I use it regularly, but I recognize I can make a "sharper" bit. NOT a more even, or long lasting, bit. Just a "sharper" one.
Look at the drill at intervals while grinding it. Leaving it in the holder, pull it out and look at the drill carefully, under good light, with corrective lenses if necessary. The chisel point should typically be at about 45-50 degrees to the cutting edges, depending on what you are going to use it for. Larger angle, gives less back relief, better for harder materials and shallower feed rate. Smaller angle, more back relief, better for softer materials and deeper feed rate. Also look at the side of the drill, at the angle of the back relief is visible where cutting edges meets the side of the drill. Less angle gives slower cut, more angle gives a more aggressive cut, but less strength. Look at the sharpening tool manual and at the link in post #7. Get a drill point gage so you can check for equal length cutting edges and equal and desired angles of cutting edges to shank.
I use a SRD drill grinder that I purchased used off eBay. It too is tricky on the relief when sharpening drills. I attached a link to my video showing me using my drill sharpener


Sent from my iPhone using Tapatalk
 

Bob Korves

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#16
I use a SRD drill grinder that I purchased used off eBay. It too is tricky on the relief when sharpening drills.
Drills have varying helix angles, which affects where the tooth rest locates in relation to the cutting edges. That is an issue when grinding drills on any type of fixture.
 
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