4th axis help please.

[John Stevenson]

I have a generic 3040 machine with manually moving bed and want to fit a 4th axis.
They do not do one for my machine but that's not a problem in that I can make one very easily [ full commercial workshop ]

This will have to mimic the X axis on this machine and use the same driver, motor is not a problem I have sourced the same motor so it's just a plug swap at the driver end.

The part I'm having trouble getting my head round is the ratio needed between motor and head so that any drawing where the X movement which will have to be X times Pi is correct when the 4th axis rotates.

Can anyone who uses a plug in 4th axis shed some light on the setup please

[Glen Monaghan]

By fourth axis and from your "X times Pi", I assume you are referring to a rotary device. Question is, will it be a roller-based or chuck-based rotary?

-Glen

[John Stevenson]

Chuck based so one rev of the chuck = Pi * X

[Glen Monaghan]

Since it's a chucked device, the motor and gearing establish a fixed rotation amount for a given input, and the distance that represents depends on the diameter of the chucked item (each degree of chuck rotation represents a smaller distance for small diameter items and a larger distance for larger diameter items). You'll have to figure out the stepping and gearing to determine what distance in your drawing represents one revolution of the chuck, and then scale the corresponding axis of your drawings accordingly. For example suppose you find that a 4" line causes the chuck to rotate 360 degrees. Then, in order to engrave all the way around a 3" diameter bottle, you take 3*pi to get the circumference, use that value to size/create your engraving design, and then shrink that dimension down to 4" and engrave. The drawing will look distorted on the screen but should be correct on the bottle.

-Glen