EMCO PCMill 4th axis

[Coopertje]

I am building a 4th axis for my EMCO PCMill 55 CNC milling machine. Since it is a very simple (and cheap) design it might be interesting for other members I thought to post it here. If these kind of things is not the purpose of this site let me know, I will move it elsewhere….

The PCMill is basically a EMCO F1 but has a bigger travel in the Y-axis and is completely enclosed. Never the less it is still a very small machine and therefor most of the standard available rotary tables are too big for the machine. Some time ago I found an Aplfa reductor in a second hand shop. Nice basis for a 4th axis and zero backlash! From the pictures below I guess you will get the idea on how I made a 4th axis out of it.







Disassembled it to clean, sandblast and spray the parts. Made all out of aluminum, for the base steel would be a better choose but did not have 20mm thick available. Also I will not use it daily so with a little of care to not dent the aluminum it should work for a long time.



The belt pulleys I have cut in the mill using a home made gear cutter. They came out nice and the belt fits perfect.





Thats all for now, if you have any question or remarks please let me know!

Best regards Jeroen

[ths]

Nice looking device there, Jeroen. What size chuck is on it, to give an idea of its total size?

Hugh.

[zeeprogrammer]

Nifty.

I did a little googling on that alpha reductor. I didn't know about such things. Interesting.

[Dave Otto]

Hi Jeroen

Thanks for posting this, a 4th axis in in my future and it is nice to see others ideas. I haven't had a chance to look up alpha reductor; is it some sort of harmonic drive?

I have included a 4th servo amp in my new control box just for this purpose.

Would like to see some pictures of it working when you get it up and running.

Dave

[dieselpilot]

Which model Alpha reducer is it?

[Coopertje]

Hugh, the chuck is a 80mm one. Total footprint is 180mm wide and 100mm deep. Center height is a 70mm

Zee, its a nice device indeed, has a planetary gearbox inside. The ration is a factor 10, so the speed reduces with a factor 10 (not imported in a hobby CNC machine, still fast enough for my kind of tooling) but the main advantage is that the torque increases by a factor 10. Due to this you can use a relatively small and cheap stepper motor of 1Nm and still have 10Nm available at the chuck.

Dave, I will post when its working, will take some time though…..

Dieselpilot, below a pic with the details of the alpha:



Jeroen

[cfellows]

Nice small unit!  The 10:1 reduction is a good ratio.  Should make a nice setup.

Chuck

[Coopertje]

Thank you Chuck. Yours looks nice too and you have a collet holder. In my opinion better then a chuck, thats gets quit quickly in the way when cutting gears. I think in future I will make a collet adapter for this unit too.

Jeroen

[cfellows]

And, likewise, I've been looking at ways to hold bigger work.  A collet chuck interchangeable with a 3 or 4 jaw chuck would be nice...

Chuck

[Coopertje]

That would be optimal indeed. Do you have an ER-11 holder on yours? The Alpha has a 16mm shaft. I will make a second adapterplate for the collets, have ER-25 collets. But with this size te locking nut is quit big again 

Jeroen

[Coopertje]

Got some more done on the 4th-axis. Sandblasted the parts and put them in my home-brewed spraying cabinet, its made out of a Ikea storage box. Put 2 ventilators in the back with a filter and mounted 2 TL lights. On the bottom a rotary plate used for cakes. It works quite well, no spray mist spread over the floor when spraying and also it keeps the dust away from the wet paint.





While the paint was drying I milled 2 side covers to close the alu tube that will be mounted over the pulleys





And mounted them in the tube with some lock-tide and give it a sandblast, ready for painting:



Here is the 4th axis partially mounted after spraying



As you can see below it fits the milling machine well, there is more then enough space for workpiece and tooling including the SK-30 holders









When I converted the machine to Mach3 I put in an extra drive for the 4th axis. Below the black connector there is a black switch where I can switch on and off the power to the drive for the 4th axis, I do not like to make connections (and especially dis-connections) under power! Another advantage of this switch is that the drive does not consume energy when not in use (most of the times) and for my feeling this will extend the life of the drive.



Next is to make some T-nuts and suitable M6 bolds to mount it to the milling table. I got some G-code from a friend of mine to have a full 4D operation on the mill, my current CAM software only supports 3.5D. The file he send me is to mill a CAM shaft, eager to try it out.

Jeroen

[fumopuc]

Hi Jeroen, that looks perfect. Good luck for the cam profile.

[steamer]

That looks awesome Jeroen!

Dave

[Coopertje]

Thank you Achim and Dave. Looking at the pictures the device could use a cover over the stepper and reducter. Lets first test it.....
@Achim: Did you ever post a how-to on how to get that superb finishing you get on your parts?

Jeroen

[Kim]

Very nice Jeroen!  I really like your spray booth there!  Clever use of a storage box
Kim