Shop built large lathe

I'm thinking of building myself a serious lathe. I have an old jet lathe that's been good but it's just not big enough for large work. My original idea was to use some I beams for the bed then I got thinking why not make a oneway style lathe. So I started looking around and saw the Robust lathe company and their design also looks good to me and using a square bed tube would make it easier to index the "way bridges "on the bed tube for welding. So either way I go I have some design elements to decide on. I would like to have a large outboard turning capability so that means left of headstock turning like the oneway or sliding headstock like the robust. I really don't see a downside to either style other than the stationary headstock would probably be more solid or at least easier to build it solid than a sliding headstock. Thoughts on this? The other thing is spindle size and thread. My jet has a 1" 8tpi but that would be to small for something this big. My southbend 9 has a 1.5" 8tpi which is what I think I will go with unless there is good reason to go with something else like 1.25" 8tpi. I suppose the morse taper to go with is #2. Is the a reason to go with a #3. I'm looking at a 25-26" swing. Any thoughts on this possibility crazy project.

I've thought about doing this myself quite a bit. As for the spindle size, I think 1.25 X 8 is the way to go. The Robust, Powermatic and others use this and accessories would be easier to get that way too. I always thought 2 square tubes would make a good bed and wouldn't be to hard to make either...for the headstock, I think it would be easiest and more stable to have a stationary headstock. I have a griz that has a sliding and pivoting headstock and it never moves. Getting it aligned after moving it is a nightmare!! So it stays put. Hope you have the time and energy to do this...so far I haven't!! I'll be watching though!

The stationary headstock also allows the system to have a smaller footprint.

I'm going to go contrary and say that I think the flat stock on top of the either a tube or a V like the oneway or robust will be easier to construct. The main downside is that you have a lot of ribbing to weld into it.. It gives you a stable reference flatform to work from though, and I think sourcing pre-ground flat and hardened stock for the ways will be easier than trying to get accurate square stock (that may depend on your shop capabilities of course.. if you have a surface grinder.. well.. lucky you!).

Having said that.. have you considered getting rid of the ways altogether and put the tail stock on rails bolted to the floor (ok technically they are still ways.. but..)? The toolrest support system could fasten to one of the rails with a pivot and have a pair of legs opposing that allowing it to be placed where ever.

Im not opposed to welding a lot. I have not thought of mounting the ways to the floor. Most of the time I won't be turning things that warrant a setup with that big of a swing and I would think that rigidity would be more difficult overall. So I think I will go with stationary headstock with threaded spindle on both sides for outboard turning, the outboard spindle can also be used to hold a hand wheel, index plate, other things I can't think of right now. Are 1.5" 8TPI threads that difficult to find things for? I think its a very common spindle on metal lathes.

1-1/4" x 8 T.P.I. is more typical, at least for Powermatics, but you can buy spindle adapters for a lot of sizes. Be sure your spindle is hollow, so vacuum attachment on outboard will work for inboard.

Crazy thoughts you say????!!!!! How about this?? http://wwideas.com/2014/11/the-biggest-wooden-bowl/

I see that 1.25" 8 TPI is more common for wood lathes now that I actually look around, although oneway has a 1.5" adapter, grizzly has one, I'm note sure about nova. Maybe the best thing to do is use a 1.25" spindle and if I need to use one of my metal lathe chucks on it then I can put a bushing on the spindle to take it up to 1.5" 8TPI.

This is what I came up with, it's not quite the original design that I was thinking of but I am happy with it. I was going to go with a welded rib bed design like oneway and robust, but I came across a guy that had 2 oliver lathe beds and I couldn't buy the steel to build the bed for the price he wanted for one of them so I just bought the bed. He also had most of a tailstock he sold me ( the casting and a quill with stripped out threads) The rest of the steel came from scrap I had around and from a friends scrap. I turned the spindle on my 9" southbend, I made it with both inboard and outboard threads. I has 1-1/2 8tpi threads, a #2 morse taper and 1/2" through bored for vacuum chucking and morse taper knockout. The curved legs were made from a bolt ring from a cell tower that was put up nearby, I think the legs, especially the tailstock end legs turned out pretty nice. So far I really like the lathe, the only thing I would have changed would be the the headstock end leg can get in the way a little, and maybe make the headstock a little shorter, which I may cut down.

Hey that came out really nice looking. Nice score on the way's! I like the solid beam headstock, that should be nice and rigid and the bearing block mounting is a thing of elegant simplicity.

Is it a single pully (pair) drive?

What did you end up with for the motor/vfd combo and what is the speed range?

That looks like an awesome lathe, Dave. Very nicely done. What's the swing and the bed length?

that look great!

You saved yourself a lot of work buying the bed like that, I'm sure it will work very well for you.

Cheers!

The swing is 26" bed length is 5'. I can swing 24" over the banjo and over 4' between centers. I have a 3hp 3phase motor with a Teco VFD with a 10 rib polyv belt and 2 step pulley I made. The speed ratios are 2:1 and 1:2.

Dave, I admire your skills! You put together a beauty and it looks solid as a rock.

Nice Job on the lathe. I thought about making a lathe. I think that this will be the path I take though.

Whoa! That's some nice work. Certainly lives up to the 'Large' in the title of the thread.

Very impressive project. Enjoy.

Grizzly introduced that model about one millisecond after I bought my G0632. Yours is more powerful and less money than the 0632.

Jonathan Shively said:

Crazy thoughts you say????!!!!! How about this?? http://wwideas.com/2014/11/the-biggest-wooden-bowl/

Click to expand...

Thank God it was a segmented bowl. I can't imagine hollowing out something that big.

Awesome job Dave.That should serve you very well!!

Thanks, I made some zebra wood handles for the banjo and tailstock (made from some zebra wood the guy I bought the bed from gave me ) I still have a hand wheel to make for the outboard spindle and mount an e-stop button somewhere. I also found a setting on the vfd that allows an external switch to select between 2 different acceleration/deceleration settings, so I can select a slow setting if i have something big mounted or a fast setting for small spindle work.