Electric motors. Where to find them and what uses them.

[Eric The Viking]

Sorry Siggy - I missed your post yesterday (at the bottom of the previous page):

Have you seen Bill Hylton's design for a Router Lathe? As opposed to leadscrews and precision gears, it uses bike gear components. The chuck has a large chain ring on the back of it, which drives a parallel shaft which is attached to a bevel gearbox. This rotates a chain along the bed of the lathe, which can be used to drive the router carriage up and down the bed by cranking it from the front. The router carriage rests on a support at the back which can take a template, so as the router is moved up and down the bed it can generate a profile along the spindle. Because of the gearing (which you can change by using different sprockets on the chuck and the bevel drive) you can rout very impressive looking spirals as well. If you're interested, the plans and details are in "Router Magic".

Many thanks it sounds very interesting. I'll try to get hold of a copy and have a look.

The things that encourage me to use a leadscrew are these:

• Metric thread studding is cheap and easy to obtain in up to 3m lengths.
• The thread pitch, again for the larger sizes, is 1mm, 1.5mm 1.75 and 2mm*, so it will also serve as a fairly precise distance measurement without complicated sums.
• If I want to drive the router lengthwise smoothly, a gearbox + small motor on the end should make that pretty easy, or possibly just coupling up to a drill chuck (I have an old varispeed B+D with a horizontal stand that might be perfect for that).

I was wondering about achieving a drive engage/disengage function too, by using a big thread and sawing a nut in half (something arranged like a clothes peg possibly, to clamp the nut on the thread and release it).

Also, if I want to go down the "CNC" route I could have a second screw controlling router height. With stepper motors, that might make spheres, etc. relatively straightforward to rough out (for wonky values of "sphere" probably).

So I guess I might adapt Bill's approach. I'll see if I can get his book out of the library locally as a starting point.

Lots more thought required, obviously.

E.

*2mm pitch starts at 14mm nominal diameter, which is maybe a bit big!

 

[siggy_7]

Interesting thoughts Eric.

The main purpose of having a geared drive between router carriage and chuck on Bill Hylton's router lathe is to cut spirals. For this purpose, I would have thought a 2mm thread form for the carriange to be far too fine to drive from the headstock as you will need to massively gear it down to get a sensible spiral pitch of say 300mm. You could achieve such gearing with a worm drive, but you're then driving the worm wheel rather than the worm which is unlikely to be successful. If you are using a CNC approach with independent drives to the chuck and carriage then this isn't a problem, but if the carriage and chuck movements are linked then it would be.

My approach, if I ever get around to building it, will be to build a 1:1 bevel gearbox for spirals and a worm drive for other turning operations, which would be interchangeable. Then I would feed from the headstock with the worm gear to get a fine pitch of router movement along the x-axis, and using the bevel gearbox feed from the carriage to get coarse pitches for spirals. But then I'm not worried about CNC capability. I think you could rout spheres without CNC quite easily though, by using an appropriate template to control the router depth as it travelled along the carriage.

If you don't have much luck finding Hylton's book, drop me a PM. Apologies to the OP for hi-jacking.