Milling for a large ring gear

A bit big for models (again): I need to cut a 'rebate' for a ring gear, about 1" deep & 1" wide, on a 24" dia flywheel weighing about 200 Kg by my calculation. I've had a couple of jobs like this in the past which I've taken away to get them turned, but after someone suggested setting up a rig to mill it in situ (not practical in this case, & the flywheel has to come off anyway), I've been wondering about doing it on my Elliott turret mill. I've got a 14" rotary table, & reckon it's just feasible to do it as far as dimensions of machine etc are concerned. There will be quite a bit of weight overhanging the side of the knee, I can probably rig up some sort of temporary support under the end of the table, as the only table movement needed will be the infeed. Even that I could probably do via the quill, and clamp the table up as solidly as possible. The machine isn't a super duper toolroom job, & not in it's first flush of youth, so I'm not too worried about pushing it to it's limits. Any comments from anyone who'se tried this sort of thing, maybe on a smaller scale, or who can see any obvious pitfalls? (apart from the risk of dropping it on my toe :-( )

I've got another very similar job coming up this winter, if it works it'll save two trips hawking bl**dy heavy lumps around the local machine shops to see who will take the job on! Also, turning it would possibly involve machining up a dummy crankshaft end (this one is a taper fit, the second one is on a bolted flange), unless I can find someone with a big enough chuck to grip the outside. The chap who did them for me before retired some years ago, he did have a nice big Swift lathe but I think that left the district.

Cheers Tim

Reply to
Tim Leech
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Tim,

Assuming that the Elliot can rotate it's turret like a Bridgeport, there is no need to have an off centre knee load. Put the flywheel on your rotary table in the middle of the table, and offset the ram of the turret to one side. I would suggest if you can rig up a drive to the rotary table it would make the job go much more smoothly (cue Tony Jeffrey and the Division Master!)

AWEM

Reply to
Andrew Mawson

Andrew

Yes it does have a rotateable turret (isn't that what makes it a turret mill?), it's only slightly bigger but much more substantial than a Bridgeport. Actually an O2 Omnimill, basically a U2 horizontal with a turret added. It'll have to overhang somewhere, just to accomodate the diameter. Precisely where & how much I haven't established yet, obviously it'll be better with the flywheel as central as possible on the knee. Up to now, I've just waved a tape measure at the mill to see that it's not a totally outrageous idea. Don't think I could justify a division master just for this job, suppose in theory I could pinch the motor off my DIY CNC dividing head & control the table from the other (CNC) mill. At the very least, I'll probably have to make up an extension for the table handle so that I can reach it. Perhaps it might be worth the effort to make the motor swappable between the two, though I was vaguely keeping my eyes open for a more manageable size of table to motorise in the longer term.

Cheers Tim

Reply to
Tim Leech

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