Lathe Ways

The little Unimat lathe used 2 parallel round shafts.

Just about anything prismatic will work. Simple or as complicated, light or heavy as you want. The first and last words work best (simple and heavy), of course...

Triangular ways are nice because you don't have any possibility of side-to-side misalignment, assuming the triange wears evenly. Witha box way, the front or rear face might wear unevenly, producing a crosswise translation at that point. In other words, a non straight path.

Dovetail ways are an improvement over box ways because the gibs provide the clamping force that's otherwise given by the bottom side clamps. Thus, less adjustment.

The next step up would be triangle ways, with gibs on the bottom? Just to hold it in place against the triangular part.

Something round has interesting properties, but no good for something that's not supposed to rotate so two rounds work. Then you would have gibs on each slide which have adjustable diameter as they wear and to clamp in place. Such is used on my drill press to hold the table in place on the column.

What else... you could do square ways, perhaps two parallel beams and do it like triangular ways, only you have four corners now.

But- without any precision tools (mill, surface grinder or planer) to produce these shapes to a high level of precision over a good length, you are basically left with scraping as your precision tool and fitting something together such as box ways. I suppose you could try scraping your own dovetail ways but it wouldn't be as easy. Certainly not as easy when you have readily available slide material such as the CRS used in the project.

Oh by the way guys, check the update on my website... I put up pics of my current progress!

Tim

-- "I've got more trophies than Wayne Gretsky and the Pope combined!" - Homer Simpson Website @

Consider shafts from a pair of matching hydraulic cylinders. The piston ends of the shafts would most likely have a nice taper and threaded stub that you could anchor to a stout plate or casting. On the other end, if they had an eye or a clevis, you could mount them to another plate or casting. Decide which end will hold the headstock, and procede from there.

NOTE: I have never tried this. It just seems a simple way to get two reasonably rigid and parallel way surfaces.

Rex the Wrench

Mark Forkheim wrote:

I would use thk liner rails for my ways.

Very good explanation, Tim! Obviously, you are speaking from experience and study re. your own lathe construction project. That is the kind of solid information needed by someone just starting off on a construction project. You are doing good work.

Bob Swinney

On the subject of round shafts for ways: I worked for a guy who has been a machinist for a long time. During the second world war he worked in a show in Seattle that built a lathe themselves for one particular type of work. Since materials and machine tools were scarce then the machine used shafting for the ways and the bulk of the machine was concrete. The concrete was cast in place to hold the ways and motor mounts. I believe the headstock was also concrete. I think the spindle was mounted in the cast headstock to some plates cast into the cement. A turret tool post from an engine lathe was adapted to the round ways. I think it was a collet machine without any provision for a chuck mount. Since the engine lathe could be used with either the tailstock or the turret, but not both at the same time, transferring the turret to a special built machine gave them two lathes to be used at once instead of just one. After the war the machine sat un-used for years and just had stuff piled on it. I suppose it's been dismantled by now. ERS

I was thinking of using hexagonal CRS. It has a couple of triangular sides. I would imagine that I would have to have the weight of the carriage/tailstock on the angled faces, not the flat on top.

How much scraping would be needed on CRS? I thought the stuff was drawn to tolerance?

Er, I was comparing the ease of using rectangular CRS to the difficulty in making one's own precision dovetail stock. Yes, CRS is pretty good. I found my stuff had a bunch of burrs on it though.. thank goodness for files!

Tim

-- "I've got more trophies than Wayne Gretsky and the Pope combined!" - Homer Simpson Website @

I do not think you will be happy with round ways. I built a large woodturning lathe, and the bed was made from a 4"x8"x1/2" thick rectangular tubing. To this was plug welded 19 lb/ft 6" channel iron. The bed is about

6' long. The rectangular tubing was orientated with the 8" dimension horizontal, and the 6" channel was then welded to the 4" sides, with the top flange about 1 1'2" above the surface of the tube. It turned out the flanges on the channel was not square so I ended up grinding/draw filing the flanges to get them flat/square/smooth. Took about a day to do this.

The tailstock was fabricated from 1/2" plate and a turned/machined tailstock. It has gibs that ride against the top vertical corners of the channel.

The lathe weighs 1500 lbs, has a 24" swing, and will mount 48" between centers.

Also, it has a compound Reeves drive, a spindle lock, a spindle brake, a tool drawer under the bed which pivots on the right front corner, all shop made.

I spent approx 1500 hrs. over a 1 year period building this lathe, but have never regretted it.

Now, having established that I know a little something about lathes (especially wood lathes), none of the wood lathes I have ever seen that had round ways were worth a fiddlers damn. Unless you can stiffen them up in some manner, they will never prove satisfactory.

To see photos of the lathe, go to

then click on 'James R. Johnson' then click on 'Click here to see lathe'.

Regards, J R Johnson

Drummond was very successful with their round bed lathe:

Leon