Warco Major CNC build log

[swarf-boy]

Hi Robin,

I have read this thread (more than once) on the work you carried out converting your Warco Major to CNC.

I too have the same machine and I am contemplating doing the same thing. (but I am new to the CNC field, but do have some local backup on seting up using Mach3 etc)

I do have a couple of questions for you that are specifc to this conversion, if you would be so kind.


Was the overall expendature and effort worth it, in terms of the usefullness of the machine when finished?

I am perticularly interested in the Z axis arangement you came up with. How is that working out for you now?

Which motors and controllers did you finally go with and on what voltage do you run them. Do still you consider them to be the correct choice?

With hindsight, is their any aspect of the project you would change and why?

[Robin Hewitt]

I do have a couple of questions for you that are specifc to this conversion, if you would be so kind.

Overall expendature and effort worth it? For me, yes. I had already CNC'd it without the benefit of CNC and as a budget job I got what I paid for. If you want to get the tolerances down, and keep them down, I think preloading nuts and screws is a good idea. The mill has 2 problems when you try to cut better than .001". The column flexes, the quill is sloppy. Grease the quill, try to keep the head wound right down when milling. Value for money? I did it because I became obsessive about seeing a couple of zero's after the decimal point on my calipers, value for money depends on how freaky you are.

The 'Z axis arangement' works well. Setting up a mill is a time consuming business, so putting in two 8mm screws to lock the Z is not exactly onerous.

Motors and controllers? I used 3.5Nm NEMA34's and Garys 240 volt drivers that come straight off the mains with no seperate PSU. The motors were rated 3A wired in series, the lowest setting on the drivers was 3.18A RMS, 4.5A peak. They seem unstallable, snapped a 12mm end mill like it wasn't there when I had a whoopsy. Not sure how fast they go, my computer can't keep up. I'm quarter stepping at 200 steps to the mm. They run a bit hot but it doesn't seem to worry them.

Anything I would change? Yes, I would mount the Y axis nut 12mm towards the front so I could have gotten the tool centre in line with the front of the bed when I cut it flat. The bolt heads collide at the back. Also a few annoying clearance errors. The Z axis digi scale top interferes with one of the bolts holding the cheeks in place, had to miss the bolt out. The Z axis handle comes very close to the Z stepper conduit clamp. I was slightly concerned that the heat from the X axis motor might be getting on to the lead screw but it doesn't seem to get above blood heat so probably okay.

[swarf-boy]

Hi Robin,

Thanks for the swift reply.

That is all very usfull info.

May I just stretch you a little more on a few points.

Do you have any suggestions on how to "stiffen" up the column

Which motors exactly did you use ( part numbers would be extremely usefull) and were did you get them from?

What is the voltage at the motors?

Thanks

[M250cnc]

I have read the whole build and it brought back memory's as i have a similar mill, i hope Robin does not mind me adding some info of how i tackled the problems.

My biggest issue was the Z axis namely the play of the quill in the headstock. I also made three failed attempts at cnc'ing the Z

My own quill had just over .1mm slack which is abysmal, i had a quote to hard chrome the quill and grind it to size of £300 and thought there must be a better way.

I cut through the front of the headstock with an angle grinder also at the top of the headstock to allow the quill bore to become flexible in diameter.

So now the quill was too tight, so i have adjusting screws that allow me to open the bore for the quill this allow me to get a beautiful fit of the quill in the headstock tight enough that there is no play but free enough that there are no issues with lost steps.

To CNC the Z i based my design on a Bridgeport mill (Getting the Nut As Close To The Quill As Possible) which i have also, by machining a slot in the quill i have mounted a custom housing that takes the ball nut it is made in steel and by using two strips of steel in the headstock i can take all the wobble out of the quill.

In fact i have the quill rotated 180 degrees in the bore as that was where it seemed to slide as easy as possible so now the the teeth for the gear are at the front.

It has two steel cheeks attached to the headstock and looks very similar to Robin's in that respect.

I do not suffer from flex in the column and my belief it that the flex in Robin's machine in fact comes from the poor fit of the quill.

Although clamping the quill will minimise problems it will not eliminate it completely.

Phil

[Robin Hewitt]

I cut through the front of the headstock with an angle grinder also at the top of the headstock to allow the quill bore to become flexible in diameter.

Hi Phil
This really does beg a picture

Robin