Need help with lathe size

[skypilot_one]

I need help deciding which size lathe to buy.

One thing I would like to do is chuck a piece of 2"X6"X.060 wall 6061 tubing, bore the end to a .030 wall thickness .060 deep so it would accept a 1.94"X.060" thick plug that has a 20 degree bevel facing out. Then spin the edge of the tube over the plug to capture it closing off the end of the tube.

What size lathe would be capable of this on a regular basis?

I would also like to be able to spin form small aluminum parts like 1/2" to 2" velocity stacks over steel mandrels.

Could a 7X14 mini lathe or 8X14 Lathemaster handle this type of work?

[2muchstuff]

Clamping 2" by .060" tube in a chuck will crush/distort it. It will need to be done on a mandrel of some sort. You could clamp the tube and mandrel as one in the chuck or clamp the mandrel by itself and clamp the tube to the mandrel. Your limiting factor here is the chuck, can it open to 2". If not then your mandrel will have to have a reduced shank and you will have to clamp your tube to the mandrel.

[skypilot_one]

Thank you for the reply.

So you feel that the loads imposed from the pressures required for spinning will not be too much for the spindle bearings or the carriage and ways on these smaller machines?

I will lock the carriage to the ways during this proceedure and use a tool rest with several fulcrum points on it to turn the velocity stacks. After the stack is formed I plan to install the regular tool rest with a parting tool to remove the excess material from the mandrel.

littlemachineshop.com has a six jaw chuck for holding thin wall tubing that opens to 3.15"

[wizard]

The other way to look at this is that you need a lathe large enough to handle a 2" id collet. Ideally this lathe would have a thru bore bigger than 2". You might sitll need a plug to go into the tub id but that could be a simple cylinder.

As you can imagine this is a realtively big lathe. I suspect you don't want to go that large. If that is the case you might get away with using an expanding arbor held between centers. This is likely to be a DIY item but isn't an impossiblity.

As far as a lathe goes I wouldn't reccomend anything less than a 9x20 for the arbor type approach. For spining also. Even then I suspect that you will have trouble. The issue with spining is that if you atart out with a sheet of steel large enough for your velocity stacks how will you turn it between centers? I could imagin you starting our with a tube but even that seems hard to do. Haven't done any metal spinning to comment further but from what I can remember from shop class none of the small lathes will do what you want with the conventional approach to spinning metal.

Thanks
Dave

[skypilot_one]

The velocity stacks are for small R/C engines, between 1/2" to 1 1/2" in Dia. and 1 1/4"-2" long. Maybe it would be best to just turn them from bar stock.

[lakeside]

to find a lathe with a 2" bore thru hole your now into a much large lathe than a mini. Small lathe that are not one piece casting from the bed to the spindle housing can have vibration issue under heavy chip load i.e. try panning but goes back to the old issue how much will you spend with all of the auto plant closing the market has a lot of good used equipment out there try this site
http://www.machinetools.com/MT/machi...p&groupid=8003

[sanddrag]

so far, I've been pretty happy with my Harbor Freight 8x12. It is actually the same lathe as the LatheMaster 8x14 but at much less cost.

[BobWarfield]

I'd turn them from bar stock, or else try metal spinning which is often used to make velocity stacks. This guy has metal spinning info on his site and will sell a CDROM:

http://www.jamesriser.com/Machinery/Machinery.html

Do you just need to make one or a few of these, or do you plan to make a bunch? If you want to make a bunch, CNC converting a 9x20 (or I prefer the 8x18 Lathemasters) would crank 'em out of bar stock lickety split.

Best,

BW