Wedg1e
They call me Mr. Bodge-angles
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- 7,745
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- Teesside, England
In my thread on Dickson tool holders I mentioned that in a moment of dextral dyslexia I put the 1ES into high rather than low ratio and shredded the teeth of a 10mm wide, 36 tooth slitting saw. Actually I'm not sure if that's the right term for a cutter so wide, one thinks of saws as being very narrow... maybe a slotting saw? 
In the past when I've done such foolery I usually just swore and binned the cutter, but that's because I'd usually bought a slack handful of cutters from Ebay for a few quid (and had no way to sharpen them).
Those days seem to have gone and individual horizontal milling cutters seem to be expensive! Besides, it's nice to be challenged on your technical skills once in a while, so I had a think.
I already have a couple of bench grinders, one of which is equipped with a diamond wheel. It gives a lovely polish on drill bits, but there's always been a midgie's todger (sorry ladies) of runout on the end face (as viewed looking onto the spindle end). Plus I was stuck for somewhere to mount it, and some way of presenting the cutter.
Then I turned around and noticed the Bridgeport
Yes, yes, I know... grinding in the lathe or mill, abrasive dust and all that... but from what I've seen of the diamond disc on the bench grinder, you get very little 'residue' (unlike, say, the green grit wheel I use for welding tungstens which dissipates all over the bloody place).
OK, so mount the wheel in the mill (some kind of arbor required) and ... then what?
Hang on a minute... dividing head. What's a div head for if not to index things around with precision? A quick shufty at the calculator suggested that one crank plus three holes on a 27-hole circle would give 36 positions, and look! One of my plates has a 27 hole circle.
Right then. So mount the abrasive in the mill spindle, mount the cutter... somehow... in the div head 3-jaw chuck and Robert is your non-transgender maternal sibling.
...tell you what, why not push the boat right out and start with a new diamond wheel?
Off to Ebay then, and one of the usual purveyors of imported machinery equipment to the hobbyist happened to have a 100m diameter cup wheel with a diamond abrasive rim. I read the feedback. Someone commented that it would have been nice if the abrasive rim was concentric with the spindle bore but wasn't, so the thing was useless.
I bought one anyway
Well, it's only money, no pockets in shrouds, can't take it with you when you go, no sense in being the richest man in the graveyard and all that...
Clocked it in the lathe 4-jaw till the body had zero runout: unsurprisingly, given that I already suspected it, the same couldn't be said of the abrasive rim. However, turning it under hand power with a DTI on the end face (the bit I'd want to use in this application) showed it actually was bang-on. Bizarre. Still, I thought I could do better and as I'd always expected to have to make an arbor for it, I reversed the wheel in the chuck and gripped it as firmly as I dared by the abrasive rim, then laboriously tweaked the jaws to get it as close to central as I could - under power the cup body could now be seen to have more runout than the England cricket team, though again, the rear face of the cup was spot on.
Then I put a boring bar (new, from the same supplier) through it and tickled it out until the eccentricity disappeared. It started at 20mm and ended up as about 20.8mm diameter. Note the DIY toolholder getting some use
Just for the hell of it I then inverted a boring bar, ran the lathe backwards and trued-up the outside face of the cup as well (a boring bar as I couldn't find another tool that would let me get in among the spinning chuck jaws).
Next it was a simple matter to knock up a stub arbor for it; as the 1ES has a 40 Int. ER40 collet chuck I made the arbor to suit the biggest collet I have, 26-25mm. The stub is slightly shorter than the thickess of the cup to ensure that a packing washer gets pulled up nice and tight by the M10 bolt.
The proof of the pudding is of course that one in a bird's bush is better than two in the hand, or something, so the cup was fitted to the mill and spun up. It was truer than anything ever spoken by a politician, which was nice.
Now, I need some way of mounting the 1" bore cutter in that chuck... which hasn't got a massive bore. Zoom in and you can see the state of the teeth
Wouldn't it be great if the spindle of the dividing head had some sort of taper in it... [unscrews chuck]... blow me, it does: a 3MT.
What we need here is... [runs off to Ebay]
A 3MT stub arbor with 1" shank (and a bunch of spacers). Given previous experience with non-concentricity of 'imported' parts I took the time to plug the arbor into the lathe's spindle (with the correct taper adapter
) and clocked it with a DTI: all good.
A quick rummage turned up a stout M12 bolt and large washer to pull the arbor into the div head taper and then it was time to cobble the whole sorry mess together and try to get the cutter square to the grinding cup face.
In the past when I've done such foolery I usually just swore and binned the cutter, but that's because I'd usually bought a slack handful of cutters from Ebay for a few quid (and had no way to sharpen them).
Those days seem to have gone and individual horizontal milling cutters seem to be expensive! Besides, it's nice to be challenged on your technical skills once in a while, so I had a think.
I already have a couple of bench grinders, one of which is equipped with a diamond wheel. It gives a lovely polish on drill bits, but there's always been a midgie's todger (sorry ladies) of runout on the end face (as viewed looking onto the spindle end). Plus I was stuck for somewhere to mount it, and some way of presenting the cutter.
Then I turned around and noticed the Bridgeport
Yes, yes, I know... grinding in the lathe or mill, abrasive dust and all that... but from what I've seen of the diamond disc on the bench grinder, you get very little 'residue' (unlike, say, the green grit wheel I use for welding tungstens which dissipates all over the bloody place).
OK, so mount the wheel in the mill (some kind of arbor required) and ... then what?
Hang on a minute... dividing head. What's a div head for if not to index things around with precision? A quick shufty at the calculator suggested that one crank plus three holes on a 27-hole circle would give 36 positions, and look! One of my plates has a 27 hole circle.
Right then. So mount the abrasive in the mill spindle, mount the cutter... somehow... in the div head 3-jaw chuck and Robert is your non-transgender maternal sibling.
...tell you what, why not push the boat right out and start with a new diamond wheel?
Off to Ebay then, and one of the usual purveyors of imported machinery equipment to the hobbyist happened to have a 100m diameter cup wheel with a diamond abrasive rim. I read the feedback. Someone commented that it would have been nice if the abrasive rim was concentric with the spindle bore but wasn't, so the thing was useless.
I bought one anyway
Well, it's only money, no pockets in shrouds, can't take it with you when you go, no sense in being the richest man in the graveyard and all that...Clocked it in the lathe 4-jaw till the body had zero runout: unsurprisingly, given that I already suspected it, the same couldn't be said of the abrasive rim. However, turning it under hand power with a DTI on the end face (the bit I'd want to use in this application) showed it actually was bang-on. Bizarre. Still, I thought I could do better and as I'd always expected to have to make an arbor for it, I reversed the wheel in the chuck and gripped it as firmly as I dared by the abrasive rim, then laboriously tweaked the jaws to get it as close to central as I could - under power the cup body could now be seen to have more runout than the England cricket team, though again, the rear face of the cup was spot on.
Then I put a boring bar (new, from the same supplier) through it and tickled it out until the eccentricity disappeared. It started at 20mm and ended up as about 20.8mm diameter. Note the DIY toolholder getting some use
Just for the hell of it I then inverted a boring bar, ran the lathe backwards and trued-up the outside face of the cup as well (a boring bar as I couldn't find another tool that would let me get in among the spinning chuck jaws).
Next it was a simple matter to knock up a stub arbor for it; as the 1ES has a 40 Int. ER40 collet chuck I made the arbor to suit the biggest collet I have, 26-25mm. The stub is slightly shorter than the thickess of the cup to ensure that a packing washer gets pulled up nice and tight by the M10 bolt.
The proof of the pudding is of course that one in a bird's bush is better than two in the hand, or something, so the cup was fitted to the mill and spun up. It was truer than anything ever spoken by a politician, which was nice.
Now, I need some way of mounting the 1" bore cutter in that chuck... which hasn't got a massive bore. Zoom in and you can see the state of the teeth
Wouldn't it be great if the spindle of the dividing head had some sort of taper in it... [unscrews chuck]... blow me, it does: a 3MT.
What we need here is... [runs off to Ebay]
A 3MT stub arbor with 1" shank (and a bunch of spacers). Given previous experience with non-concentricity of 'imported' parts I took the time to plug the arbor into the lathe's spindle (with the correct taper adapter
) and clocked it with a DTI: all good.A quick rummage turned up a stout M12 bolt and large washer to pull the arbor into the div head taper and then it was time to cobble the whole sorry mess together and try to get the cutter square to the grinding cup face.
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