lathe chuck spindle

Hi,
I bought a 4" 3jaw lathe chuck off ebay, and am adapting it as a 4th
axis for my milling machine. The lathe chuck has a backplate with a
1.5" (1 1/2") spindle bore, and 1-1/2"-8 threads (8 threads per inch)
Is there an off the shelf pipe I could buy to thread into this and put
a couple bearings on the pipe to function as the lathe spindle? I think
I might have to make this spindle on a lathe but it would be nice to
not have to!
cheers,
Jamie
Reply to
Jamie M
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Jamie M fired this volley in news:k42cqe$5hm$1 @speranza.aioe.org:
Break out the lathe, and get to work! Pipes are seldom "straight threaded", but taper-threaded. A tapered thread wouldn't fit the chuck properly.
Besides, the US-standard thread for 1-1/2" pipe is 11-1/2tpi. You don't get up to 8tpi until 2".
LLoyd
Reply to
Lloyd E. Sponenburgh
Not really, other than the headstock from a scrapped lathe. You could remove the backplate to mount the chuck on the mill table, or buy a chuck with a 5C mount and a 5C spin index to hold it.
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I made a short 1-1/2" - 8 arbor that fits in a 1" 5C collet to attach a 1-1/2 - 8 Jacobs chuck to my 2-1/4" - 8 lathe spindle.
Reply to
Jim Wilkins
1-1/2" x 8 is available thru McMaster Carr as threaded rod (and nuts), but the thread class fit is 2A. You might want to spend the time making your own piece where you can get it to fit more to your liking.
Reply to
Denis G.
It doesn't take long to do once you get set up. I made a dummy spindle end for making chuck backplates, took an hour or so. That's NOT a standard fastener or pipe thread. Or you could make a backplate to fit whatever you're going to hook up the chuck to and fit it to the chuck in place of the current backplate. Almost as much work as the dummy spindle nose, I've done both. A three jaw wouldn't have been my choice for such things, you can tweak a workpiece in a 4 jaw to be a lot closer on center, but that's me.
Stan
Reply to
Stanley Schaefer
Hi,
I think I will use some cold rolled steel tube, 1.5" OD and 1" ID, then put the 8TPI threads onto that, hopefully the tube will work for 1.5" ID bearings. What type of bearings would be good to use? I probably will use two bearings I guess and would like to have some axial pretension to get rid of axial play in the spindle, so need some axial load as well as radial load bearings. Maybe a single thrust bearing and a single roller bearing? Or an angular contact bearing and a roller bearing maybe. Also what is the best mechanism to apply the axial preloading?
cheers, Jamie
Reply to
Jamie M
Jamie M fired this volley in news:k459oh$ol$1 @speranza.aioe.org:
Angular contact with a pre-loading nut.
But don't count on merchant stock tubing being oversized enough to fit properly. It might be. It might also be a few thou. small.
Buy a piece of "hollow rod" stock suitably oversized, and turn it to fit the bearings. Then you can also shoulder the piece so the bearings have something to press against in pre-load.
LLoyd
Reply to
Lloyd E. Sponenburgh
"Lloyd E. Sponenburgh" fired this volley in news:XnsA0DCC14EA3C80lloydspmindspringcom@216.168.3.70:
I should have said "...bearings on both ends", and the shouldering is only required on one end, the nut provides the other "shoulder".
But the shaft must fit the inner race diameter with a snug sliding fit or a bit tighter if you have a press and mandrel to put it on. You're not likely to get that fit with merchant stock steel sized to the nominal dimension you want.
LLoyd
Reply to
Lloyd E. Sponenburgh
What is the point of adding a lathe spindle to a milling table? You don't need bearings to use it as a rotary index that you clamp TIGHTLY before making the cut.
Do you already have another lathe to machine this spindle on?
jsw
Reply to
Jim Wilkins
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Reply to
PrecisionmachinisT
Hi,
I'm making something similar to this:
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cheers, Jamie
Reply to
Jamie M
Cool. How much do you think you can save by making your own? That's not a bad price point.
Reply to
Larry Jaques
About $300. with shipping...
I would probably just buy a harbor freight mini, tossing any un-needed parts; much sturdier
Reply to
PrecisionmachinisT
Excellent!! VERY well supplied!
Gunner
Liberals - Cosmopolitan critics, men who are the friends of every country save their own. Benjamin Disraeli
Reply to
Gunner
Jamie,
For a 1.5" x 8tpi threaded spindle I would look at using maybe 2" bar to start with so you can have an abutment for the chuck threaded mounting plate to abut against. The various lathes I have used such as Myford and IIRC Southbend are like this and the location is done by the abutment and a short plain section next to it before the thread, not the thread itself. If you look in your chuck you may well find a plain before the start of the thread. In you chuck case can you remove the mounting plate? it may need to if possible to true to get the best running of the plate on your spindle.
Also consider how to lock the chuck from rotating on the spindle so that cutting forces can't unscrew the chuck.
Also check prices on metric bearings as they are often cheaper due to larger volumes, shouldn't be an issue if you're making the parts you make it to the size required.
Reply to
David Billington

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