Buget Warco Major 5 axis conversion

[Robin Hewitt]

Hi Mark

Overhangs are tool tip extension from the chuck, how far the chuck projects below the quill, distance you wind the quill down to make the cut, height of the workpiece above the bed.

Small cuts are not a problem for CNC once you have got past the teething troubles and trust your setup and G Code not to go hideously wrong. A large job may take hours but that's okay for a hobby machine which doesn't have production deadlines and can simply be left to get on with it. Trust is the key to that, when it stabs you in the back find out exactly what went wrong and fix it once.

You will "hog it out" as our American chums would say. Rapid removal of the excess material followed by fine finishing cuts. Only problem with that is chatter can leave vertical striations which echo in to the finishing cut. A speed change can help.

You have to experiment and find out what you can get away with on your machine, unfortunately there doesn't seem to be much rhyme or reason to it. You settle on a fine finishing cut, then one day it goes horribly wrong and ploughs in to the body of the work. An enormous cut that comes up with a fine finish and you wonder why you aren't cutting it all that way.

HSS tooling takes a sharper edge than carbide but doesn't last as long. If you want a fine finish don't fall in to the carbide trap. A centre cutting tool is a bad idea if you are trying to get a fine finish on a horizontal surface but is essential if you want to plunge.

Lubes. A bottle of Rocol RTD is a good start. A suds pump is better than a brush, especially if you want to run it unattended, but that probably precludes the milling vice because it will dump the run off on the floor. Incidentally, very tempting to buy an enormous milling vice but that's a big overhang. If using suds a wet and dry vacuum cleaner makes chip removal and clean down a doddle. I run the suds back in to the tank through a filter bag to protect the pump. Cast iron should be cut dry but I have recently had luck with paraffin as a lube, expect to find hard spots. Avoid cutting stainless, it is horrible.

Cutting downhill is a good idea unless you have backlash issues. If you cut an external counter-clockwise the tool will tend to bend in to the job, if you go clockwise it will shy away from it. The tool tip will always leave a line regardless, some people hone a tiny radius on the end to prevent that, I've never tried it, prefering to go full depth on the final pass. It all depends on what your machine will let you get away with.

I have probably rambled enough, but let's have one more... avoid tool changes unless you have a really sneaky method to reset the tool height with incredible precision.

Have fun

Robin

Edit: One more, cockpit checks. When you get in an aeroplane you go through a list, hatches and latches, tight and secure, brakes on, off, pressure exhausted etc. Before you set the milling job in motion have a check list. Particularly, are the chuck, drawbar and clamps on that round column stupidly tight. Do you have enough movement on the table to do the job? Will a G0 run the tool through a hold down fixture? The spanner Warco supply to clamp on to the round column isn't up to the job, suggest a socket or a box spanner, or extend the nuts so you can get a ring spanner on them. The Warco drawbar head is held on with a pin and is best replaced in toto.