# Drill sharpening jig



## th62 (Aug 27, 2014)

This is a drill sharpener I've just finished:   I used a piece of 25mm square bar, linished it, milled a V for the drill, cut a 2mm slot down the centre for 110mm, drilled a stepped hole through: 5mm for 30mm and then 11.5 mm for the remaining 110mm. I had to extend an old 11.5mm drill and grind flat on the end so I could machine the end of the hole flat for a stepped bush to run on. I also drilled a couple of debris drain holes and tapped a few 5mm holes for mounting the slide plate, the end plate and the drill clamp. As you can see from the pics there are quite a few bits inside. 

The 5mm advance rod was turned down to 3.5 on the end and a 5mm bush with collar was shrunk in place for the end bushing. I turned a bit of stock to 7mm, threaded the inside to 5mm x .8, fashioned a single wing and tacked it to the nut. The bush on the advance end was machined to 7mm with a collar, machined down to fit a 9mm spanner, and threaded inside the same as the advance screw. When screwed into place it’s locked off with a locknut. The plate on the end has a backlash adjuster and locknut and also acts as the outer bearing for the advance screw bush. The end plate is fixed by two 5mm allen heads which I had to turn down to accommodate the backlash adjuster locknut. To the rear of that are the thumb lock nut and the thumb adjuster.

The drill clamp U piece is attached via two 5mm allen heads. I machined a stepped 5mm nut and shrunk it into the top of the U piece. The adjuster screw has a thumb nut attached at the top and the adjuster screw pushes an H shaped plate down onto the drill flutes.

It will accommodate drills from 25mm down to 2mm, but in reality larger bits are probably better ground using a simple conical grinding jig attached to a linisher. Anything under 4 or 5mm would be difficult to grind accurately on this jig, so next project will probably be a jig with a drill chuck for smaller bits.

In use: The drill is secured in place by the adjuster and H plate. To advance the drill onto the grindstone, the advance thumbnut is turned and the single winged nut moves along the advance screw, guided by the slot in the bed, and acts on the rear of drill pushing it forward and onto the grindstone...

It was made on my 280 x 700 lathe as I don't have a mill, I experienced some mounting difficulties as I don't have a vertical slide, but in the end it came together quite well.

The wooden box I finished off today.

Over complicated? Sure is, but it works well; and, it was an excellent project to design and make.


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## Gerritt (Aug 27, 2014)

Beautifully done, right down to the custom box.

It also goes to show how much can be done without a full machine shop. 

I have a Taig lathe with vertical slide, with some material mounting ingenuity you can make a lot of things.

Gerrit


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## Rbeckett (Aug 27, 2014)

I don't think it is too complicated because it does produce an excellent edge on every bit within it working capability.  That sharpened bit looks like it was done at a special shop and is way better than my puny little drill doctor would ever produce.  I bet it makes bits just plow through material quite nicely too!  Now you have me wanting a better sharpening jig...

Bob


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## richz (Aug 27, 2014)

th62 would you happen to have a drawing?


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## 12bolts (Aug 27, 2014)

Very impressive!
Is it possible to adjust the angle formed by the chisel point?



Cheers Phil


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## th62 (Aug 27, 2014)

Sorry, I don't work from drawings unless the job is extremely complicated, and of course, what job ends up the same as the drawings anyway.   I think the pics and description give a pretty good idea though.   One tip, make it longer than mine (about 25mm), this will shorten the overhang (allowing for a flute indexer).   To make it longer you will need a longer than standard  11.5 mm drill.

Chisel point angle is largely governed by the relief angle and to a lesser extent the primary angle, the more acute they are, the more acute the chisel point angle.   If grinding on the front of the wheel the grind will be slightly concave, so the relief angle will need to be ground at a more acute than normal angle otherwise the heel of the relief face will be in contact with the work (unless grinding multi facets); thus, the chisel angle will also be more acute.   Hope that makes sense...


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## Smudgemo (Aug 27, 2014)

Very nice project!  I just started on a grinder rest project that should make for this sort of result, and now I'm especially looking forward to using it.  Perhaps I'll be able to ship the Drill Doctor to my dad for a new home as the results look excellent.

Cheers!
-Ryan


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## HMF (Aug 28, 2014)

Awesome project. Wish I had those skills! Thanks so much for posting it!!


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## oldnotdead (Sep 3, 2014)

th62 said:


> This is a drill sharpener I've just finished:   I used a piece of 25mm square bar, linished it, milled a V for the drill, cut a 2mm slot down the centre for 110mm, drilled a stepped hole through: 5mm for 30mm and then 11.5 mm for the remaining 110mm. I had to extend an old 11.5mm drill and grind flat on the end so I could machine the end of the hole flat for a stepped bush to run on. I also drilled a couple of debris drain holes and tapped a few 5mm holes for mounting the slide plate, the end plate and the drill clamp. As you can see from the pics there are quite a few bits inside.
> 
> The 5mm advance rod was turned down to 3.5 on the end and a 5mm bush with collar was shrunk in place for the end bushing. I turned a bit of stock to 7mm, threaded the inside to 5mm x .8, fashioned a single wing and tacked it to the nut. The bush on the advance end was machined to 7mm with a collar, machined down to fit a 9mm spanner, and threaded inside the same as the advance screw. When screwed into place it’s locked off with a locknut. The plate on the end has a backlash adjuster and locknut and also acts as the outer bearing for the advance screw bush. The end plate is fixed by two 5mm allen heads which I had to turn down to accommodate the backlash adjuster locknut. To the rear of that are the thumb lock nut and the thumb adjuster.
> 
> ...



Love it, I hope to make one like it..


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## righto88 (Sep 3, 2014)

Very nice design and looks like it does a very good job sharping. Also great workmanship. :man:


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