Lawnmowerboy
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Drills I've ground nearly always cut within 2 to 3 thou.
- Thread starter breezer
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brightspark
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that can easily be achieved with practice
but the hole wont be perfectly round it will be oval on a small drill .3 thou is a lot specialy if your tapping ba threads . and before anyone comes up with it drills dont cut perfect round holes they have to be reamed or bored
Lawnmowerboy
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Plus you can't choose what sort of rake you want or grinding a drill to cut oversize or for soft or hard or thin materials.
Lawnmowerboy
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A drill will never cut on size even new carbide drills will nearly always cut big unless in a cnc
brightspark
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i just scored a proxon drill sharpener unused for 90 quid of ebay .145 the cheapest u can get them. it looks well made but i havent used it yet , 2 busy i sharpen most by hand and have the reliance drill sharpener as well .i have 3 sets of drills used only for good stuff on lathe and drill 1 metric 1 imperial set and a set of number drills and 2 sets of general purpose drills . will give the sharpener a go when weather improves http://www.ebay.co.uk/itm/Proxxon-D...de-21200-/151141262634?_trksid=p2054897.l4275
I agree. Practice makes perfect. And if the drill is really too tiny to grind a replacement is very cheap anyway.
Its not really the cost of the drill but getting it (post or fuel) and the inconvenience. (or waiting)
Wedg1e
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In an absolute emergency when on site, I've sharpened drills using a hand-held angle grinder... enough to get the drill cutting again, if not the last word in rake angle and web thickness! Even put new cutting edges on snapped drills found on the floor as that was the only thing to hand at 7PM Friday within minutes of finishing a job 200 miles from home...
Buy From cromwells then, free delivery and will probably do the same for home users if you talk to them nicely. They are normally a helpful and obliging crowd
Kind regards,
Scott
Wallace
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I think the YouTube video is misleading, all the tools in the background are for woodworking as are the Tormek website and the holes shown drilled in steel look bloody awful. The grinding wheel he is using needs a diamond run across to true it up.
Lawnmowerboy
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I was gonna say the wheel is out of balance. Obviously a very skilled woodworker but you're right about the holes drilled in metal.
brewdexta
The biggest tool in the box
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I got time to try out the Tormek, tonight. I only had about 30 mins so I didn't choose a drill too challenging the first time round, I chose a 10mm dormer jobber with a slight chip from enlarging a smaller hole and was generally a bit dull.
My first attempt was just a little off, you have to align the cutting edges in the jig so they are parallel with a line, next attempt much better and its v.sharp and looks just like the 4 facet picture. I haven't had time to try the drill yet, had to come indoors to babysit.
Its very easy to set the point angle between 90 and 150 degrees, I selected a standard 118 which was similar to the original profile. Clearance angle is also easy to select between 7 and 14 degrees. I used 11.
takes a few seconds to mount the jig
The wheel has been dressed to be fine as the last time I used it I was putting a secondary bevel on a wood plane blade. Ideally it should be dressed to be rougher with the grading stone but it worked fine for this trial.
The drill mounted in the holder after grinding the primary facets, crap photo, I'll have to get the missus SLR out to show the effect after grinding the secondary facets and the nice 4 facet point it creates.
This is my "needs sharpening" tray, I may be a while! I think you can get it down to a few minutes per drill for a light grind but if the drill has been butchered I may use the grinder to take some of the worst off without heating it too much.
My first attempt was just a little off, you have to align the cutting edges in the jig so they are parallel with a line, next attempt much better and its v.sharp and looks just like the 4 facet picture. I haven't had time to try the drill yet, had to come indoors to babysit.
Its very easy to set the point angle between 90 and 150 degrees, I selected a standard 118 which was similar to the original profile. Clearance angle is also easy to select between 7 and 14 degrees. I used 11.
takes a few seconds to mount the jig
The wheel has been dressed to be fine as the last time I used it I was putting a secondary bevel on a wood plane blade. Ideally it should be dressed to be rougher with the grading stone but it worked fine for this trial.
The drill mounted in the holder after grinding the primary facets, crap photo, I'll have to get the missus SLR out to show the effect after grinding the secondary facets and the nice 4 facet point it creates.
This is my "needs sharpening" tray, I may be a while! I think you can get it down to a few minutes per drill for a light grind but if the drill has been butchered I may use the grinder to take some of the worst off without heating it too much.
brewdexta
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So after the 10mm I thought I would try something chunkier with a bit more damage, so here's a half inch Dormer with a chunk out of it. The previous drill was with the wheel was graded to 1000 grit, for this bigger drill I regraded it to 220 grit with the grading stone which takes about 30 seconds.
here's the primary facets cut and half way down the secondary, you can see that its still a chisel rather than a point so a bit more grinding needed. You can see that I haven't got rid of the whole chip, the depth adjuster is 0.5mm per turn so I should probably have given it another turn on the primary facet. I shall wear my glasses next time! The red fibres are off my jumper where I wiped the drill.
So here's the drill with the secondary facet cut so the facets meets at a point.
Here's that ragged edge, I'll wait until I'm back on the 1000 grit for smaller drills and take another 0.5mm off later
Here's a better view of the previous 10mm drill to show that it does make a nice clean edge
I'm going to try a Swedish Malcus 22mm next which is as big as it can go then a 4.3mm cobalt drill which I'll probably need the magnifier that comes with it to align it.
Verdict, does a lovely precise job at the angles you want and its pretty simple once you have used it a couple of times. It's not too bad speed wise but as the manual suggest, on bigger or damaged drills its probably worth taking some meat off on the grinder first, especially on the secondary facets/. Cost wise, only really makes sense if you already have the Tormek grinder. You can use Tormek jigs on a standard grinder with an adaptor I think it would work fine as long as the wheel diameter is reasonably large, the drill holder easlily comes off so you could quench the drill frequently if the grinder wasn't water cooled.
here's the primary facets cut and half way down the secondary, you can see that its still a chisel rather than a point so a bit more grinding needed. You can see that I haven't got rid of the whole chip, the depth adjuster is 0.5mm per turn so I should probably have given it another turn on the primary facet. I shall wear my glasses next time! The red fibres are off my jumper where I wiped the drill.
So here's the drill with the secondary facet cut so the facets meets at a point.
Here's that ragged edge, I'll wait until I'm back on the 1000 grit for smaller drills and take another 0.5mm off later
Here's a better view of the previous 10mm drill to show that it does make a nice clean edge
I'm going to try a Swedish Malcus 22mm next which is as big as it can go then a 4.3mm cobalt drill which I'll probably need the magnifier that comes with it to align it.
Verdict, does a lovely precise job at the angles you want and its pretty simple once you have used it a couple of times. It's not too bad speed wise but as the manual suggest, on bigger or damaged drills its probably worth taking some meat off on the grinder first, especially on the secondary facets/. Cost wise, only really makes sense if you already have the Tormek grinder. You can use Tormek jigs on a standard grinder with an adaptor I think it would work fine as long as the wheel diameter is reasonably large, the drill holder easlily comes off so you could quench the drill frequently if the grinder wasn't water cooled.
johnakay
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just weld two large nuts together that'll give near correct angle.
as long as there is no high spots you'll be fine.
I've never had problems do it this way.
an old engineer bloke taught me years ago on how to sharpened drill bits this way.
it may not be the correct way but it worked for me.
as long as there is no high spots you'll be fine.
I've never had problems do it this way.
an old engineer bloke taught me years ago on how to sharpened drill bits this way.
it may not be the correct way but it worked for me.
brewdexta
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