Thread: Neat is a more beterer jig.

Neat.

BT

Originally Posted by th62

This is my final drill sharpening jig. Rather than spot bits of angle together, 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’s quite a bit heavier than the previous jig I made, but also quite a bit shorter at just over 180mm long, it’s not quite as fiddly to use as the first jig and seems to do a better job (see pics of drill point.

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

Excellent work ! I very much like the pusher for the drill feed adjustment.

Very nice work th62.
There is only one problem I can see with it, and that is, it isn't in my shed.
It beats the hell out of buying one in my opinion, way more satisfaction in making it.

Phil

It's beautiful.
And besides that, it does a beautiful job.

pretty nifty jig that one .now we need a set of plans .

johno

One thing I do not like about it is the very long diagonal line at the tip...

When you look at drills sharpened when new, the point is a very short line running straight across the shortest part of the web at nearly 90 degrees to the cutting edge..

Hi RC,
I think you,ll find thats as good as four facet get(maybe a little less secondary relief angle?)
Unless you go to split point.

Stuart

though the names can be tricky as what I call four facet others call split point .

Wasn't too sure what you meant at first. Stustoys is correct I believe: grinding on the front of the stone creates a concave relief with a slight upweep toward the tail. Reducing the relief angle would probably see the tail rubbing on the work, or at the very least not provide enough relief at the tail (particularly on bigger bits). There are two answers I can think of: grinding six facets, or grinding on the side of the wheel. Grinding on the side of the wheel has an unwanted shaping effect on the stone over time, for that reason I made the jig to sit at the front. Bigger bits over 14 mm, I think, are better sharpened on a simple conical jig, simply because it's easiest and there's a lot more metal to remove on a damaged bit.

I think most new drills are conical ground and then the web thinned to create a point - of sorts. There is a commercial conical grinding jig available that also provides for web thinning, can't think of the name though. I would imagine web thinning on small bits would be a tad difficult and require a much better stone than I have.

Today shall be arborist day me thinks: why do all slit saw blades have different size centres?

I just realised I've doubled up on this post. I've just removed the other, to relieve my confusion.

can this be purchased from you?

Hi th62,

A picture from Tormek, I'd say you're pretty damn close to that.(whos got some angle measuring software?)
http://www.tormek.com/images/marketi..._drill_bit.jpg

This is a split point, you need to control cross feed so need a good corner on the wheel and I don't think you'd get away with a "flat" primary clearance.
http://ecx.images-amazon.com/images/I/71bCkCb6jGL.jpg

I wonder what you would get if you ground it as per your picture but had a cross feed stop.....maybe a cross between the two. But the stop would have to be set pretty accurately and you might end up with a couple of delicate corners... I'm not so sure it would be worth the bother and would go with what you've got until you find an issue with it.

Stuart

Nicely finished and looks good!

I'll leave Stuart to measure the angles...

Ray