Is it doable to put risers under Harding HCT headstock to make custom lathe with 18"?

richard newman · Jun 21, 2018

Is it doable to put risers under Harding HCT headstock to make custom lathe with 18"?

Can I reasonably easily put riser blocks under the the headstock of a HCT to increase swing to 18" or more?

I use a 24" x 96" patternmakers lathe to make banjo rims, don't need more than 18"cc, would like to have a much shorter machine to save space. Don't need 24" swing, 18" would do.

Also, with the tapered spindle nose can one run a 8" chuck in reverse. This would be for light cuts in wood, and maybe brass, no hogging.

atomarc · Jun 21, 2018

Richard,

I can't answer your question but I wonder if you have considered doing this a different way. I know a gent that does this same chore using a recently purchased green lathe with a bear on it..in a gap bed version. He permanently removed the gap and cut the ways back several inches. He uses a 8" chuck with giant pie jaws on it. He can turn 18" rims. I built the adapters for the pie jaws to fit his chuck. The picture shows them mounted on MY lathe for a trial fit..not his lathe.

Stuart

dkmc · Jun 21, 2018

Well, the short answer is a question....
Why not?

As far as "reasonably easily".....that's another matter altogether.
For one thing, the drive belt needs to get longer......one way or another.
Which might mean a modified drive system, as the Hardinge belts use their own taper on the sides, so no 'stock' longer belt (if available) will really work.
It all seems plausible to me IMHO.

As far as the bayonet lock spindle taper, you can lock it in either direction, so
running reverse should not be an issue.

EDIT: Stuarts idea seems a whole lot simpler!

bsg · Jun 21, 2018

Your basically looking for a small T-Lathe?

What about a horizontal mill with a lathe chuck, or shorten the lathe you have?
You could also find another lathe that would be a better candidate for shortening?

The problem I see with (Raising In The Sand) of the Hardinge, the headstock has dovetails that are fit to the lathe bed, probably not a big deal if your just turning wood?

Good luck and let us know how you solve this...........

Kevin

bsg · Jun 21, 2018

car2 said:
Another option may be a Hardinge TM/UM horizontal mill or similar. Part is fixed to the spindle, the toolholder is clamped to the table; if angular movement is needed a cross-slide can be attached to the table. Cheers

You beat me to it!

I have one of these as a parts machine that could be had pretty cheap!

Kevin

bsg · Jun 22, 2018

car2 said:
...great minds think alike I've used my TM on a couple of occasions for this purpose. The only (rather obvious)thing to note is that whatever workholding device us used (for example a chuck or plate on a 5-c mount), the mount must have a feature to engage the *spindle drive notches*, the 5c holding-power alone shouldn't be used for any high-torque/force application.

I agree, but he is going to be cutting wood and brass so it shouldn't be a problem?

Also when using a horizontal mill you can use the table feed for moving the cutter across the part!

Kevin

rons · Jun 22, 2018

richard newman said:
Can I reasonably easily put riser blocks under the the headstock of a HCT to increase swing to 18" or more?

If you cut the away the bed ( :ack2:

) at the headstock you will get a whole 3/4" for 1.5" total. Any more distance and you will be cutting into the casting for the bed support. Not worth it.

sfriedberg · Jun 22, 2018

bsg said:
he is going to be cutting wood and brass so (workholding in a 5C collet) shouldn't be a problem?

I'd call it a potential problem, personally. With a 9" lever arm on the work and the limited taper contact area on a 5C collet, I would not be comfortable. I don't like 5C collets for 1" diameter tools (in steel), so 18" diameter work (in wood) starts getting into the same territory.

mTeryk · Jun 22, 2018

You wouldn't hold the work in a 5c collet. You'd mount a chuck using a 5c back plate, the back end of which is integral and shaped to fit in the 5c taper of the spindle. I've seen these for 3 and 5 inch chucks but not 8.

I did this with my TM before I got a lathe but not for anything that big. Not sure it would be my choice as a dedicated machine. The lack of longitude feeds and lame cross feeds being the major shortcomings.

Teryk

Sent from my XT1710-02 using Tapatalk

bsg · Jun 22, 2018

sfriedberg said:
I'd call it a potential problem, personally. With a 9" lever arm on the work and the limited taper contact area on a 5C collet, I would not be comfortable. I don't like 5C collets for 1" diameter tools (in steel), so 18" diameter work (in wood) starts getting into the same territory.

I don’t know why you changed my quote? I never suggested using a 5C collet, I was saying, I didn’t think the loads would be that high if you are reasonable on your cuts?
I would hope he would make a dedicated work holding fixture?

Kevin

sfriedberg · Jun 23, 2018

Kevin/bsg, I changed "it" to "(workholding in a 5C collet)" because that's what I thought you were saying, based on what you quoted in your posting, and was trying to be clear in what I was responding to. "It" could refer to any number of things. Evidently I interpreted your post incorrectly, my apologies

bsg · Jun 23, 2018

sfriedberg said:
Kevin/bsg, I changed "it" to "(workholding in a 5C collet)" because that's what I thought you were saying, based on what you quoted in your posting, and was trying to be clear in what I was responding to. "It" could refer to any number of things. Evidently I interpreted your post incorrectly, my apologies

No apologies needed, but thank you anyway! I can see by reading my post where the assumption would have come from, I didn’t make it clear enough!

Unfortunately my typing cannot keep up with my brain sometimes, or is it the other way around?

If I was the OP, I would be looking for a small horizontal mill with a 40 taper spindle anyways, but I don’t know if he has the capability to move a machine of that size and or the available space for it? He would have to tell us what kind space he is dealing with?

Kevin

neilho · Jun 23, 2018

The AHC's headstock was fastened to the bed with 4 SHCS's. Did a couple CNC conversions to such that involved a headstock riser. Easy enough to do, and the dovetail beds, IIRC, are the same size as the hand chuckers. But, sacrificing two lathes to make one doesn't seem very economical. Seems like making a spacer to the existing (I assume) chucker would be very doable.

richard newman · Jun 23, 2018

Thanks for the replies, some good info and suggestions. The query was prompted by a really cheap HC that showed up on craigslist. This is not urgent, but I've been contemplating downsizing again sometime in the vague future, and I just won't be needing or have room for a 10' long 3000lb lathe. At the moment I also have an old Leblond Regal 17" , SB 9, and Hardinge DSM, not looking forward to having to thin the herd.

The HSM is just so solid and smooth, so I wondered if the HC could be a good foundation for me, as it has a moving carriage with longitudinal feed. I'd have to cobble together a cross slide and swiveling compound. The odd belt profile complicates things for sure tho.

I'd also thought about a small horizontal mill, but the y axis travel parallel to the spindle is pretty short. I'd like at least 12", if not more. As for supporting the work, 5C seems kind light to swing a 8" 3 jaw chuck, which is what I use with pie jaws. The cutting forces really minimal, but I need stability.

I'd been thinking to post my problem on the general forum, I'd love to see what gets suggested. Would be great to come up with a relatively easy solution, but unfortunately I have a reputation for taking on stupidly difficult projects, but executing them well.

rpseguin · Jul 11, 2018

atomarc said:
Richard,

I can't answer your question but I wonder if you have considered doing this a different way. I know a gent that does this same chore using a recently purchased green lathe with a bear on it..in a gap bed version. He permanently removed the gap and cut the ways back several inches. He uses a 8" chuck with giant pie jaws on it. He can turn 18" rims. I built the adapters for the pie jaws to fit his chuck. The picture shows them mounted on MY lathe for a trial fit..not his lathe.

Stuart

View attachment 231247

Those soft jaws are huge with such a large overhang!
How fast is he spinning this? I wouldn't want to be around those going at any fast speed.

atomarc · Jul 11, 2018

rpseguin said:
Those soft jaws are huge with such a large overhang!
How fast is he spinning this? I wouldn't want to be around those going at any fast speed.

The customer and I agreed that nothing over 10K should be attempted with these jaws!

Stuart

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