7x10 Lathe For Turning Down Ends Of 3/4threaded Rod?

[Cavediver]

Hello all,
Absolute newbie here in the metal world. I just bought a used 7x10HF lathe and currently have it stripped down for cleaning and whatnot.

I'm planning my first project: a powered drill press table lift for a 1950's-ish Craftsman drill press.

I'll be using a 3/4"-6 x 24" acme threaded rod to move the table up and down, powered by a stepper motor and control board.

My question: is it reasonable to turn the ends of this rod down for (bearings and drive couplers) using the 7x10 lathe? I have purchased the LMS 4-Jaw chuck (plenty of clearance for the rod to pass through it and the headstock), and am planning 2-3 outboard supports (steady rests?) for the rod to the left of the headstock.. Supports will likely be plywood construction, HDPE bushings, and will be anchored to the bench with through-bolts.

I would like to turn each end of the rod down to 3/8" or 1/2". The bottom end of the rod will sit on a thrust bearing (requiring a nice, square shoulder) and be connected to the stepper motor with either sprockets and chain or some shop-made delrin gears. The top end will also be turned down to 1/2" to fit in a bushing.

Thank you,
Jay


End note: There will be a lot of baby steps between here and there. I have a ton of research to do, lots of practice cuts to take, etc. It will be about a month while I'm cleaning up the drill press (recent CL purchase) and getting the piece drawn up, plans finalized, etc.

 

[JimDawson]

Sounds like what you are planning will work fine. A well planned setup.

 

[ch2co]

I shouldn't think that you would have any problems doing this. It sounds like you have thought it out pretty well. I'd love to see your plans and be sure to include a few pictures before, during, and after. Just be sure take it slow at first and get it situated with that length sticking out of the left side.

CHuck the grumpy old guy

 

[joshua43214]

Sounds like you are thinking through stuff well. I am especially happy that you intend to support the outboard side - there are some real horror stories about not doing this.

One point to consider is the steppers. Steppers are more efficient at lower speeds, and power drops off rapidly above a certain threshold speed. Have you done the math to make sure the table will move fast enough, yet still be inside the steppers power band? It would kinda hurt if you went through the whole job and it still took less time to raise it by hand. You might be able to get away with just using a DC motor and a cheap speed control.
I once built what amounted to an elevator for raising a 200lb load about 10' using threaded rod at each corner and a chain drive. I drove it with a motor from a garage door opener. It raised the load at about same speed a garage door opens, worked like a charm. Just a thought for an alternative source for junk.

 

[Cavediver]

Thanks all.
I think I know what I'm doing here. Unfortunately, that's when I usually get in trouble, so I thought I'd better ask

...there are some real horror stories about not doing this.

I read one last night over at OWWM, and yeah... Scary business can happen if you don't pay attention to details and think your plan through.

Have you done the math to make sure the table will move fast enough, yet still be inside the steppers power band?

Nope.
Not yet, at least. I just bought this press yesterday after having looked at it last weekend. I'm still thinking all of the parts through in my head and will soon commit to paper / CAD. I have some steppers and controllers at the house, and one or two other DC motors that might work.

The drill press is in surprisingly good condition. The table appears to have only one oops, there are a few bolts missing, and the rest of it is dirt and surface rust. It does not have a lift mechanism at all; it's a hunk of cast iron clamped on a post at the moment, so anything, even if it is slow, will be an improvement.

 

[stupoty]

Hello,

If your sticking a lot out of the back end of the spindle watch out for the bar whipping if you run it at too high an rpm.

It's amazing how bendy a piece of metal can abuptly get

The outbord suport can probably be just the wood with a clerance hole in it, maybe a bit of oil on it if it's tight.

Good luck,

Stuart

 

[atunguyd]

I suspect that if you put it right on the end you will only need one outboard support. Pretty much like on the lathe with tailstock support you don't need mid suport for the workpiece to turn without whipping around.

Sent from my SM-N920C using Tapatalk

 

[Cavediver]

I suspect that if you put it right on the end you will only need one outboard support. Pretty much like on the lathe with tailstock support you don't need mid suport for the workpiece to turn without whipping around.

Sent from my SM-N920C using Tapatalk

Good deal. That's save me a bit of work and setup time. Thanks for the heads-up!

 

[Heckle and Jeckle]

Using my drill press I find it not uncommon and need the ability to offset the table. The intended hole does not always line up with the proper clearance. .

If the machine is production and process constant, then that is a good feature, not the case otherwise.


just saying
greg

 

[Cavediver]

Using my drill press I find it not uncommon and need the ability to offset the table. The intended hole does not always line up with the proper clearance. .

If the machine is production and process constant, then that is a good feature, not the case otherwise.


just saying
greg

Agreed.

Oddly enough, I put this project on hold due to a hang-up in the restoration of the drill press. I finally solved my issues and am trying to get it finished up this weekend. Once that's done I will get back to work on the lift.

In any case, I am thinking of two possible solutions to this issue: either clamp the lift to the table and allow the bottom of the mechanism to pivot around the column, or clamp the lift firmly on the column and attach it to a pseudo sleeve bearing at the top with the table riding above it / on the top face of said sleeve bearing, possibly on a thrust bearing of some sort.

The former could work, though I think it will be complicated and clunky.
The latter is my preference, but I don't know how to pull that off given my lack of welding and machining capabilities.

Once I reassemble the press I will be able to determine my motion requirements and will draft up the concepts so I can get a couple of quotes from a local fabricator.