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Wedg1e
They call me Mr. Bodge-angles
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good call, and an excuse to dust off the rotary table 
Might take some thinking about how I'd clamp the wheel down though, maybe a big bolt through the table centre bore... my dividing head is horizontal only, as you can see further up.
Looking at the length of that drawbar, you could reach my house from yours with it
Wedg1e
They call me Mr. Bodge-angles
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Hmm, this isn't going according to plan. The new knurling stick arrived, but it's too big for the lathe 
Not just that the shank is too large for my holders, I expected that and could soon mill it down, but the head is so bulky that even with the topslide wound all the way back the tool won't clear the drawtube handwheel when held in the chuck.
So, I thought bugger it, I'll go with the scalloped edge idea... but when I come to measure up, my 12" rotary table won't fit under the vertical head on the Bridgeport (it's only a 1ES not a Series 2) - well it will, but not with the handwheel clamped to it
Which leaves using my Perrin, on which I know the rotary table will fit and there's clearance, but as it's not strictly a mill and the head is only clamped to the round column by friction, so there's a risk of the head deflecting under cutting load and shagging the part (technical description
)
Another possibility that occurs is to see if my dividing head will clear the 1ES's chuck, position the handwheel horizontally and mill the scallops with a ball-ended cutter... if I have one. I bought a selection of screwed-shank cutters a few weeks back, there might be one amongst that lot.
There was a part-dismantled 1ES sold on Ebay a few days back, it had the modified overarm with a BRJ-style head on it which gives the 1ES more versatility, but it went for £500 which was about twice what I'd have wanted to pay just for the bits I fancied - on the plus side, if a 1ES in kit form is worth that much, things are looking up: I've seen them fail to make £100 not so long ago. The last complete 1ES with BRJ head on Ebay went for £1800!
Not just that the shank is too large for my holders, I expected that and could soon mill it down, but the head is so bulky that even with the topslide wound all the way back the tool won't clear the drawtube handwheel when held in the chuck.So, I thought bugger it, I'll go with the scalloped edge idea... but when I come to measure up, my 12" rotary table won't fit under the vertical head on the Bridgeport (it's only a 1ES not a Series 2) - well it will, but not with the handwheel clamped to it
Which leaves using my Perrin, on which I know the rotary table will fit and there's clearance, but as it's not strictly a mill and the head is only clamped to the round column by friction, so there's a risk of the head deflecting under cutting load and shagging the part (technical description
)Another possibility that occurs is to see if my dividing head will clear the 1ES's chuck, position the handwheel horizontally and mill the scallops with a ball-ended cutter... if I have one. I bought a selection of screwed-shank cutters a few weeks back, there might be one amongst that lot.
There was a part-dismantled 1ES sold on Ebay a few days back, it had the modified overarm with a BRJ-style head on it which gives the 1ES more versatility, but it went for £500 which was about twice what I'd have wanted to pay just for the bits I fancied - on the plus side, if a 1ES in kit form is worth that much, things are looking up: I've seen them fail to make £100 not so long ago. The last complete 1ES with BRJ head on Ebay went for £1800!
Wedg1e
They call me Mr. Bodge-angles
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As a thread-filler I thought I'd add that I ran the offcut of 'bronze' through the PMI at work and it came back as about 89% Cu, 7.5% Sn, 2.5% Pb and a bit of Zn... a composition which doesn't appear to exist - i.e. Unobtanium
Based on published data it's evidently a leaded tin bronze, I think CDA 920-series (C92700 for example). The high copper content suggests it's not C93200 which is a very common bearing alloy (according to Leeds Bronze).
What the hell, it works and it was free
I thought I'd add that I ran the offcut of 'bronze' through the PMI at work and it came back as about 89% Cu, 7.5% Sn, 2.5% Pb and a bit of Zn... a composition which doesn't appear to exist - i.e. Unobtanium Based on published data it's evidently a leaded tin bronze, I think CDA 920-series (C92700 for example). The high copper content suggests it's not C93200 which is a very common bearing alloy (according to Leeds Bronze
).What the hell, it works and it was free
Wedg1e
They call me Mr. Bodge-angles
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I may have worked out how to cut the scallops, but it'll mean a bit of close running... I'd had a bit of a brain fart earlier and forgot that the head on the 1ES mill can be swung, so I flipped it over to 90 degrees and cranked the table up to see where the dividing head ended up (this is what you might call a compact workshop!):
The head's about 7" centre height but the Elliott all-steel chuck on it is missing its internal jaws which would have been a better option for holding the handwheel.
To improve working clearance I think I'll move the head to one of the other T-slots; the table edge clouts the reducton drive gearbox on the vertical head which means I'd have to make the cuts on the blind side, '9 o'clock' on the 3-jaw if you follow. If I swap slots I'll be able to cut at the '3 o'clock' position, ie. near the operator. Another issue is the diameter of the cutter: it'll need to be at least 12mm otherwise the collet chuck body will foul the 'boss' of the handwheel before it cuts anywhere near deep enough. Trouble is, all my large endmills are plain shank, which would mean using the ER40 chuck, which has a larger nut...
Rough and ready alignment using a pair of centres: should be close enough for the intended task though. Dividing head has been bolted down after running a DTI along the side of the chuck body to ensure parallelism (which does assume the chuck isn't tapered)
Playing with Autocad suggests 15 scallops at 4mm depth. What I might do is turn a thread on some 5mm aluminium rod and wind short lengths in to plug the grubscrew holes. With a light finish cut after the scalloping, the holes should all but disappear. I was going to have the three grubscrew holes aligned with the scallops but the risk is that the cutter might chip on the screws if they're not deep enough, so placing them between the scallops might be safer.
The head's about 7" centre height but the Elliott all-steel chuck on it is missing its internal jaws which would have been a better option for holding the handwheel.
To improve working clearance I think I'll move the head to one of the other T-slots; the table edge clouts the reducton drive gearbox on the vertical head which means I'd have to make the cuts on the blind side, '9 o'clock' on the 3-jaw if you follow. If I swap slots I'll be able to cut at the '3 o'clock' position, ie. near the operator. Another issue is the diameter of the cutter: it'll need to be at least 12mm otherwise the collet chuck body will foul the 'boss' of the handwheel before it cuts anywhere near deep enough. Trouble is, all my large endmills are plain shank, which would mean using the ER40 chuck, which has a larger nut...
Rough and ready alignment using a pair of centres: should be close enough for the intended task though. Dividing head has been bolted down after running a DTI along the side of the chuck body to ensure parallelism (which does assume the chuck isn't tapered
)Playing with Autocad suggests 15 scallops at 4mm depth. What I might do is turn a thread on some 5mm aluminium rod and wind short lengths in to plug the grubscrew holes. With a light finish cut after the scalloping, the holes should all but disappear. I was going to have the three grubscrew holes aligned with the scallops but the risk is that the cutter might chip on the screws if they're not deep enough, so placing them between the scallops might be safer.
Agroshield
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For the future, maybe ponder the implications of cutting at 12 o'clock (so long as the noise does not annoy the neighbours).
That way, you can put a packer/jack between work and table so the cutting forces go into the table. Also, I think with an odd number of scallops, the 6 o'clock should always be uncut so you do not have to touch the jack when indexing. With the head at non-ninety degrees, you can cut tapered scallops.
If you can make your grub screw plugs from identical material, they will as you say all but disappear.
That way, you can put a packer/jack between work and table so the cutting forces go into the table. Also, I think with an odd number of scallops, the 6 o'clock should always be uncut so you do not have to touch the jack when indexing. With the head at non-ninety degrees, you can cut tapered scallops.
If you can make your grub screw plugs from identical material, they will as you say all but disappear.
Wedg1e
They call me Mr. Bodge-angles
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Right then
As I hadn't started scalloping when Agro posted his last suggestions, I decided he did have a point; the only reason I was going to machine at 3 or 9 o'clock positions was that the knee feed on the 1ES is rather heavy, but even if I overshot on depth it wouldn't really matter.
Which meant I needed a screwjack.
Which I didn't have.
So I made one
In the interests of material economy I initially decided against chopping up more of that lovely 65mm alloy bar, and instead found some spacer tubes from a 2-post car lift. Unfortunately I didn't take a pic, but what occurred to me was that I could use that random offcut of bronze to make a top-hat that would drop into any one of the spacers (they come in different lengths depending on what you're trying to lift on the, er, lift). So I started by cleaning up the bore...
and then turned to the only piece of steel I could find that was large enough to fill it, which was this:
I have no idea what it's made of but it's as hard as hell. I spent about half an hour trying to make a dent in it before giving it up as a bad job. To be fair it also had a large crack in it, but for what I needed I figured what the hell...
Which left me needing a Plan B. I found a length of 1" bar that started life as an axle on a radioactive transport container (I kid you not, it had a Cobalt-60 source in it and when we had to dispose of it the transport company told me to angle-grind all projections from the body!). Anyway, I monkeyed yet another 20tpi thread onto it (note original split-pin hole, I intended to use it for a tommy bar)...
...and then whilst rummaging through my drawer of odd stock I found a scrap ultrasonic reference block that had failed metrology: it's 7075T6 aluminium and machines beautifully. I used my patented 'knock the middle out with a hole saw' technique...
...and a corresponding thread was soon added:
I tapped the screw M6 both ends as well, thinking of possible future accessories. To try it out I used a piece of lead to protect the handwheel and decided that for this job it probably doesn't need a tommy bar otherwise I might jack the handwheel all out of skew, like one o't crossbeams on't treadle () :
but then decided that with a little extra effort I could make an acetal 'shoe' that would match the curve of the piece. The dividing head went across to the Perrin and a scrap of 25mm acetal was chucked. The boring head is spinning here, it's been frozen by the camera but you can probably make out that the bar at right is upside down - of necessity. If I ran it the correct way up it would have to spin backwards and would unscrew the head, which is threaded to the spindle.
The boring bar was installed this way to keep the offset of the head to a minimum; that meant some careful measuring of the head to get the right amount of bar 'stickout'. The acetal stayed in the chuck and the finish looked OK...
and of course the proof of your uncle Bob's pudding is that a stitch in time gathers no moss, so I sat the 'shoe' on the handwheel and...
Close enough
Now...
As I hadn't started scalloping when Agro posted his last suggestions, I decided he did have a point; the only reason I was going to machine at 3 or 9 o'clock positions was that the knee feed on the 1ES is rather heavy, but even if I overshot on depth it wouldn't really matter.
Which meant I needed a screwjack.
Which I didn't have.
So I made one
In the interests of material economy I initially decided against chopping up more of that lovely 65mm alloy bar, and instead found some spacer tubes from a 2-post car lift. Unfortunately I didn't take a pic, but what occurred to me was that I could use that random offcut of bronze to make a top-hat that would drop into any one of the spacers (they come in different lengths depending on what you're trying to lift on the, er, lift). So I started by cleaning up the bore...
and then turned to the only piece of steel I could find that was large enough to fill it, which was this:
I have no idea what it's made of but it's as hard as hell. I spent about half an hour trying to make a dent in it before giving it up as a bad job. To be fair it also had a large crack in it, but for what I needed I figured what the hell...
Which left me needing a Plan B. I found a length of 1" bar that started life as an axle on a radioactive transport container (I kid you not, it had a Cobalt-60 source in it and when we had to dispose of it the transport company told me to angle-grind all projections from the body!). Anyway, I monkeyed yet another 20tpi thread onto it (note original split-pin hole, I intended to use it for a tommy bar)...
...and then whilst rummaging through my drawer of odd stock I found a scrap ultrasonic reference block that had failed metrology: it's 7075T6 aluminium and machines beautifully. I used my patented 'knock the middle out with a hole saw' technique...
...and a corresponding thread was soon added:
I tapped the screw M6 both ends as well, thinking of possible future accessories. To try it out I used a piece of lead to protect the handwheel and decided that for this job it probably doesn't need a tommy bar otherwise I might jack the handwheel all out of skew, like one o't crossbeams on't treadle (
) :but then decided that with a little extra effort I could make an acetal 'shoe' that would match the curve of the piece. The dividing head went across to the Perrin and a scrap of 25mm acetal was chucked. The boring head is spinning here, it's been frozen by the camera but you can probably make out that the bar at right is upside down - of necessity. If I ran it the correct way up it would have to spin backwards and would unscrew the head, which is threaded to the spindle.
The boring bar was installed this way to keep the offset of the head to a minimum; that meant some careful measuring of the head to get the right amount of bar 'stickout'. The acetal stayed in the chuck and the finish looked OK...
and of course the proof of your uncle Bob's pudding is that a stitch in time gathers no moss, so I sat the 'shoe' on the handwheel and...
Close enough
Now...
Wedg1e
They call me Mr. Bodge-angles
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...to make the real one, since that was just an odd scrap.
Fitted to the screw:
...and the whole setup returned to the Bridgecock Adleyport:
Two full cranks and 34 holes, I think it was, on a 51-hole circle. Just to make sure I did a trial run and marked the top of the handwheel at every division, the 16th cranking put no.1 back at the top, which was a start:
It was then a case of picking a spindle speed for the 10.6mm cutter (no idea why it was that size, it was the largest 4-flute screwed-shank I had that was long enough to pass clear through the thickness of the handwheel rim) - 760rpm I think - and then get into the rhythm of undo screwjack - undo clamp on div head spindle - crank handle - clamp up - readjust screwjack - take cut. A bit like this:
...which eventually got to this (the handwheel is 90mm diameter, not 100mm as I thought the bar was that it came from):
A wee chamfer was later added to knock the square corners off, and I deepened the 'dish' as well. Yes, there is a cutter nick in the corner of that scallop, I dropped the crank plunger a hole too early. Luckily I spotted it before I'd gone very far. A steeper chamfer would get rid of it
I remembered I'd suggested blanking plugs for the grubscrews that hold the hub and rim of the handwheel together. A length of 10mm alloy rod was spun down to 5mm and an M5x0.8 thread single-pointed on:
After a quick blow-out with compressed air, a drop of threadlock was added to the grubscrew holes and the 5mm rod wound firmly in before being parted-off with a padsaw (even I'm not daft enough to spin THAT up
)
The handwheel was then chucked back on (not at!) the lathe and a gentle tickle with an HSS tool brought the blanking plugs down to match the OD, but of course in relative terms a 0.8mm pitch thread is quite coarse so they didn't quite disappear completely:
Fitted to the screw:
...and the whole setup returned to the Bridgecock Adleyport:
Two full cranks and 34 holes, I think it was, on a 51-hole circle. Just to make sure I did a trial run and marked the top of the handwheel at every division, the 16th cranking put no.1 back at the top, which was a start:
It was then a case of picking a spindle speed for the 10.6mm cutter (no idea why it was that size, it was the largest 4-flute screwed-shank I had that was long enough to pass clear through the thickness of the handwheel rim) - 760rpm I think - and then get into the rhythm of undo screwjack - undo clamp on div head spindle - crank handle - clamp up - readjust screwjack - take cut. A bit like this:
...which eventually got to this (the handwheel is 90mm diameter, not 100mm as I thought the bar was that it came from):
A wee chamfer was later added to knock the square corners off, and I deepened the 'dish' as well. Yes, there is a cutter nick in the corner of that scallop, I dropped the crank plunger a hole too early. Luckily I spotted it before I'd gone very far. A steeper chamfer would get rid of it
I remembered I'd suggested blanking plugs for the grubscrews that hold the hub and rim of the handwheel together. A length of 10mm alloy rod was spun down to 5mm and an M5x0.8 thread single-pointed on:
After a quick blow-out with compressed air, a drop of threadlock was added to the grubscrew holes and the 5mm rod wound firmly in before being parted-off with a padsaw (even I'm not daft enough to spin THAT up
)The handwheel was then chucked back on (not at!) the lathe and a gentle tickle with an HSS tool brought the blanking plugs down to match the OD, but of course in relative terms a 0.8mm pitch thread is quite coarse so they didn't quite disappear completely:
Wedg1e
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On the lathe...
I may or may not knock some of those extra threads off; I was thinking that a possible addition might be a screw-on cap like a gland nut, with a guide to hold the outer end of any long bar stock and stop it whipping around.
Also, there's enough meat in the handwheel that I could take a bit extra out of the bore, tapered to match the collet closer, and it'd give the closer somewhere to live while not in use...
Apart from that, all I need now is some 5C collets. Oh look: there are some for sale on Ebay...
Next, it's either a spindle brake for the Boxford or modifying the Perrin so the head is keyed to the column so it can't rotate under cutting load. It's a shame the factory didn't do it, for a drill it's massively overbuilt. It'll need a keyway machining along the column for a start... just the sort of job for, say, a Beaver
Apparently some Boxford VSL's had an electromagnetically-operated disc brake that operated on the non-drive end of the motor shaft. I was thinking something hydraulic... like, say, from a small motorcycle
Internal threading up to a shoulder when you can't drop the halfnuts or use a carriage stop can be a bit - a brake could be a better option than guessing how long the chuck will take to spool down in backgear.
I may or may not knock some of those extra threads off; I was thinking that a possible addition might be a screw-on cap like a gland nut, with a guide to hold the outer end of any long bar stock and stop it whipping around.
Also, there's enough meat in the handwheel that I could take a bit extra out of the bore, tapered to match the collet closer, and it'd give the closer somewhere to live while not in use...
Apart from that, all I need now is some 5C collets. Oh look: there are some for sale on Ebay...
Next, it's either a spindle brake for the Boxford or modifying the Perrin so the head is keyed to the column so it can't rotate under cutting load. It's a shame the factory didn't do it, for a drill it's massively overbuilt. It'll need a keyway machining along the column for a start... just the sort of job for, say, a Beaver
Apparently some Boxford VSL's had an electromagnetically-operated disc brake that operated on the non-drive end of the motor shaft. I was thinking something hydraulic... like, say, from a small motorcycle
Internal threading up to a shoulder when you can't drop the halfnuts or use a carriage stop can be a bit - a brake could be a better option than guessing how long the chuck will take to spool down in backgear.
Last edited:
Agroshield
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I am enjoying this thread as the writing is as good as the machining.
On the screwjack, perhaps have a look at the latest YT from 'Craig's Workshop'. Lots of useful tips there.
On the disguising holes, you can cut the material a little proud, and peen it over (pointy punch or flat-faced) before skimming to better hide the join.
On the brake, consider bicycle disks as well. They come in cable and hydraulic, and the cable ones could be activated by a solenoid. Another possibility is air conditioning electromagnetic clutches.
Wedg1e
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Well, this isn't as done and dusted as I'd hoped. Remember I bought a 5C collet to use as a trial piece? Well I bought a dozen used ones from the bay of evil, some Hardinge, some Crawford and a couple of others... and only one of them fits my closer. Not only that, but only half of them will screw into my drawtube, and they're definitely all 20tpi.
A bit of measurement shows that the only one that will fit is exactly the same diameter as my bought one, to half a thou"... something like 1.2465". Of the 'new' set, even those that measure 1.2470 won't fit! I realise the spec. is usually 1.25" so I guess I'll have to seat the closer firmly and take a shave off the bore... and the internal thread in the drawtube will need deepening: the ones that do fit are about 1.230" thread OD but even 6 thou" bigger won't screw in (spec. says 1.238").
Guess what I'm doing this weekend
Agro, the choice of motorcycle brakes was somewhat influenced by the spare front caliper and master cylinder I have from a Yamaha 125; I bought it to replace the one on my daughter's YBR but it turned out to be the wrong one, Yamaha fitted two around the time her bike was built... the seller initially offered to take it back or swap it but then went mysteriously quiet, presumably hoping I'd give up. I was thinking the brake light switch would be wired into the stop circuit of the inverter so it kills the drive as you apply the brake.
A bit of measurement shows that the only one that will fit is exactly the same diameter as my bought one, to half a thou"... something like 1.2465". Of the 'new' set, even those that measure 1.2470 won't fit! I realise the spec. is usually 1.25" so I guess I'll have to seat the closer firmly and take a shave off the bore... and the internal thread in the drawtube will need deepening: the ones that do fit are about 1.230" thread OD but even 6 thou" bigger won't screw in (spec. says 1.238").
Guess what I'm doing this weekend
Agro, the choice of motorcycle brakes was somewhat influenced by the spare front caliper and master cylinder I have from a Yamaha 125; I bought it to replace the one on my daughter's YBR but it turned out to be the wrong one, Yamaha fitted two around the time her bike was built... the seller initially offered to take it back or swap it but then went mysteriously quiet, presumably hoping I'd give up. I was thinking the brake light switch would be wired into the stop circuit of the inverter so it kills the drive as you apply the brake.
