4th axis do-it-yourself

[zaebis]

Ok I have a benchtop (x4 like) CNC that works great. It came with controller and 4th axis board. All that is missing is 4th axis itself. I am thinking about 4" item. I know I could just buy one off the shelf but I would like to convert one myself ! I need a rigid donor rotary table and a stepper motor to get started. Any suggestions?

[philbur]

Pick an RT that has good backlash adjustment, both on the gear engagement and the worm shaft. You can live with a bit of backlash on a manual RT, it can be a nightmare on a CNC RT.

Phil

Ok I have a benchtop (x4 like) CNC that works great. It came with controller and 4th axis board. All that is missing is 4th axis itself. I am thinking about 4" item. I know I could just buy one off the shelf but I would like to convert one myself ! I need a rigid donor rotary table and a stepper motor to get started. Any suggestions?

[degreaser]

Here's one I made from a 4" Phase II table. The table was purchased from LMS. The table has a backlash adjustment and you can make it as tight as you like.

[irving2008]

Here's one I made from a 4" Phase II table. The table was purchased from LMS. The table has a backlash adjustment and you can make it as tight as you like.

Thats very similar to a conversion I am doing at the moment. Did you do anythign to the shaft - e.g. fit thrust washers or other bearings, or just bunged the motor on?

[degreaser]

No thrust washers, I just used the stock movement. That's a good idea though.

It currently has a homebrew lovejoy coupler to connect the shafts but I'll eventually replace that with a helical coupler.

[kanton]

Here's one I made from a 4" Phase II table. The table was purchased from LMS. The table has a backlash adjustment and you can make it as tight as you like.

degreaser,

How large is the hole through the center of your fourth axis?

Thanks.

[degreaser]

Kanton - do you mean through the rotary table/chuck bore or through the NEMA23 mount?

Through the bore, it's around .597". I'd have to pull the mount off to get the other measurement but the ID of the mount is the OD of the backlash adjustment bushing on the table. It's around 1.25".

[jalessi]

Degreaser "Don",

Is the stepper mount for your fourth axis one piece?

It looks very good.

Jeff...

[degreaser]

Thanks! Affirmative. It was turned from some 2.25" 6061 square stock.

[kanton]

Kanton - do you mean through the rotary table/chuck bore or through the NEMA23 mount?

Through the bore, it's around .597". I'd have to pull the mount off to get the other measurement but the ID of the mount is the OD of the backlash adjustment bushing on the table. It's around 1.25".

degreaser,

I wanted to know the approximate maximum diameter of a long item that you could fit through your fourth axis?

Thanks.

[degreaser]

That would be .597". That's limited by the design of the 4" Phase II table.