Lathe design - best fittings etc

[Luke Hospadaruk]

Before I get going - the last time I turned any wood was on a 9v battery powered kid's lathe in elementary school - so I wouldn't say I've got a whole lot of turning experience.

For various reasons (it's super cool) I've decided I need to build myself a lathe. I'm sure I could find a used one that would get the job done, probably be cheaper and better, blah blah blah, but I need a project to work on and it's going to be a lathe. In this particular case, it's going to be a treadle powered lathe (not only do I need a project, I also need exercise). I may later add a motor, but I don't really want to bother with that for now. And my questions would really be the same for a motorized or non-motorized lathe.

There's a nice little PDF here (http://www.manytracks.com/lathe/lathe.pdf) about building treadle lathes where most of my crazy ideas are coming from. Instead of describing the whole design to you, just take a look and see what I'm generally going at. Also attached are some pictures showing the basic idea.

Since I get to design everything about this lathe (and I've never used/owned a real lathe) I've got a lot of questions about what decisions to make.

Main questions:

1) What kind of fittings should be on the spindle? I'm imagining a female MT2 on either end (inboard and outboard), with a bore-hole through the middle so I can use a draw bar. Is this as standard as I think it is? Will I have an easy time finding fittings (drive centers, sanding plate, chuck, etc) that fit onto this? I have a friend who can machine the spindle, but if there's some cheaper option that will get the job done (he doesn't work for free), that would be desirable.

2) Does the outside diameter of the spindle really matter - are there any fittings (chucks, centers, plates, etc) that fit onto the outside of spindles?

3) Tailstock - probably just going to use a stock MT2 socket set into wood - maybe with some welded-on flanges to keep it secure, maybe weld it to a plate and bolt the plate to the top of the tailstock. This I'm not very worried about - again so long as I'll have an easy time finding MT2 live/dead centers, etc.

4) How big should I make this thing? I can pretty much go as big as I want (within reason and fits-in-the-basement rules) in terms of distance from bed to spindle and overall bed length. Probably if I go too big the lathe will loose some stability (bad), but I can't imagine I'll go that big.

5) Anything you really wish your lathe did/had that it doesn't that I should design for?



Other design thoughts:
- I plan on pouring a concrete flywheel for maximum mass. I'll probably use a round belt and a v-grooved flywheel/drive pulley instead of a flat belt and crowned pulleys. v-groove seems easier to set up.

- I may make it out of some local hardwood, birch or maple - or I may just use dimensional lumber. I was considering using LVL (those structural laminated roof beams) for the horizontals, they're huge and I'd imagine very dimensionally stable. I don't really want the whole lathe to be propeller shaped a year from now.

- I'd like to be able to turn just about everything (eventually, skills and tools permitting). I don't really want to build another lathe a year from now so I can turn X thing. Although as long as I can re-use the expensive bits (spindle/bearings/flywheel/tailstock) re-doing the wood parts wouldn't be the end of the world.

- It's fairly easy (read:inexpensive) to get pillow-block and flange-mounted ball bearings for any likely shaft diameter, that's probably the route I'll go (as opposed to bronze/hardwood/plastic bushings, or just sitting the spindle in a hole).

[Reed Gray]

I had never thought of using concrete, but it could work. The one in the picture looks like a weight was added for balance, and being an old concrete man, getting it perfectly round, axle hole centered, and balanced could be a problem. I have a friend who made one, and he used a brake drum from a car. Maybe a big one from a heavy truck could work. Sounds like a fun project.

robo hippy

[Luke Hospadaruk]

I'll probably drill the axle hole in what I roughly estimate to be the center, then balance it by drilling out concrete from the heavy side (or maybe screwing weights into the light side - that might be easier depending on how out of balance it is). Perhaps double-stick on lead weight during balancing and then screw it in for permanence.

As for roundness, so long as it's balanced I don't think perfect roundness is critical (although certainly desirable). I might try to get a slice of jumbo-sized sono-tube from somewhere.

I'm thinking about using clay stuck to the inside of the form to manage the v-groove, or perhaps carved-away spray foam.

[charlie knighton]

if you are going to turn out of balanced pieces, (as is found wood) add an outrigger on the side that you will be rotating to most, i believe there is one other wood lathe around here someplace, go for it,,follow up pictures as you solve problems

[Scott Conners]

Great project! My advice would be to try and get some time on a modern powered lathe before building yours. Even a single session would give you SO much more information to go by when making decisions. What part of the country are you in? There is probably a woodturner near you that would let you have a bit of shop time. Check out the AAW website to find the wood turner's guild near you, I guarantee if you showed up to a meeting someone would want you to come turn. Many woodcraft/rockler/other woodworking stores also have lathes setup and do demo days, or will even do lessons or let you try it out.
To me, a home built tool like that is never finished, it just gets changed or added on-to whenever I find a new idea or need a new capability.

[Dennis Ford]

Since this lathe is human powered, it does not need large diameter capability. I would think that 12 inch diameter capability would be plenty. A 12 inch diameter bowl would be very large for the power source, requiring light cuts (for quite a while).
A MT-2 would be important for the tail-stock so that you could use stock live-centers, drill chucks etc. A MT-2 would be useful for the inboard spindle end, the outboard end would not need a taper in my opinion. (Cutting the tapers will be the most expensive part of the machine work)
I agree with the pillow block bearing idea. I don't think much of the idea of welding a flange to a morse taper socket. A well made tail-stock is the most difficult part of a home-made lathe.

[Rick Markham]

Luke, it's entirely possible to make the wheel out of concrete. One of my childhood friend's father was a potter, he had built his wheel himself, it was foot powered and the the wheel you kicked was a giant concrete wheel he had poured, (it had to have been close to 1000lbs of concrete) once you got it going it just kept right on going. As Reed said, it's probably pretty tricky to get it balanced, but his seemed to run extremely true, and turned like it was balanced on the head of pin. I have no clue how he did it, if I had been older (or still lived around there) I would have asked.

[Mike Cruz]

Sorry, Luke, I'm in a bit of a hurry right now, so, I might not be answering any of your questions, but my advice would be to use something else besides pine. There is a lot of vibration that goes on with lathes. I think pine would wear out/loosen up rather quickly. I would use the hardest, cheapest wood you can find (might be white oak or hard maple). For the tool rest, again, the hardest wood you can find...might want to splurge there and get something like lignum vitae... Best of luck!

[Luke Hospadaruk]

Did a little more research on spindles - I'm thinking 1" diameter shaft with 8TPI threads on the outside and MT2 on the inside - both inboard and outboard (probably will almost never use the outboard taper, might drop it depending on how expensive it is to machine.

I may try and get a spindle off ebay that has a MT2 and matching threads for the tailstock. I saw some that came off smaller table-top lathes at generally reasonable prices - probably cheaper than the cost of having even a pre-made socket machined with threads.

To get the tailstock concentric I'm thinking to put a drill chuck in the spindle and use the lathe to bore the tailstock, then fit whatever taper piece I end up using (be it salvaged lathe spindle into the hole.
I could possibly get my tailstock socket knurled on the outside, then slice the tailstock vertically along the lathe axis (with a bandsaw) and use bolts above and below the socket to lock it in (but permit it to be removed for service).

Another possibility would be to put a threaded hole in the back of the socket and run a bolt through the back of the tailstock into this threaded hole. This would however block me from ever using a drawbar or drill bit through the tailstock (do the scrapers used in narrow-mouthed vases go through the tailstock usually?).

[Luke Hospadaruk]

I'm in ann arbor and we have a pretty good supply of locally-cut hardwoods. I have a lot of possibilities, the final choice will probably depend on what's most affordable when I call up the sawmill. I'm leaning towards birch or hard maple, as I'm lead to believe they have probably some of the better dimensional stability out there (which I imagine to be important to keep everything in alignment since I'll probably mostly use solid beams).

Any other woods I should be on the lookout for especially? Sometimes a weird tree gets cut from someone's yard and there's a sudden supply of something a little more exotic.

[Mike Cruz]

Hard maple would probably be just fine. I don't know about birch, not that I don't think it will work, I just don't know about its specific properties.

Another thing to consider is laminating pieces. Actually, there's a guy selling butcherblock countertops for really cheap. I think they are 2 1/2" thick. You could get some of those, and cut them to size for your structure. Laminated wood is very strong and stable.