Thread: Warco Major CNC build log
When Garry at Zapp finishes machining my ball screws I'm going to have another go at CNC'ing my poor old Warco Major mill.
The plan is to have all the milling done for the X and Y axes so I can strip the machine back then do all the final fitting using a lathe.
The story so far is the pile of bits in the piccy, only a couple of parts left to mill before I'm ready, wonder what I've forgotten.
The theory is simple, combine Garry's 20um backlash screws with a 5um half step resolution and see what it does
Hope Gary gets me my screws soon, I'm running out of bits to make.
Had a bit of a fright when I located the bolt holes that hold the Y handle to the machine. They look like they were drilled at random with a Black and Decker. One is far from straight, had to drill my hole far from straight to match.
Need to buy some grub screws, best selection and price seems to be from J & S Fasteners, they offer a choice of tips so I can get a flat point rather than those horrid cup ends. I've used them before, have a link...
More when the screws arrive
4 days off, a good time to start
First the Y screw. On the Warco the Y screw locates in to a 21mm diameter pocket 6mm deep cut in the bottom of the carriage (First pic).
I had to finish the nut holder after the machine was apart so I left a rod projecting out the other side for chucking it in the lathe. Looking to mininmise backlash I cut an interference fit with a groove around the bottom to catch any crut.
Pic 2 shows the Y nut fitted but not screwed down yet.
Pic 3 shows the carriage fitted with the spindle sticking out. The first of 2 angular contact bearings is fitted.
The idea is to hold the shaft between two angular races with a quarter ton of thrust locking it in place. To get a quarter ton I'm using pairs of belleville washers.
I have to crush the washers by 1mm and it would be nice if the nut ended up flush with the end of the shaft so I measure it, Pic 4, at 2.95mm then remove 1.95mm from the collar in the lathe.
The fitting has to do both push and pull on the ball screw so it's one solid lump of T6 alloy with a plate for the stepper screwed to it.
Next the X axis. Warco bolt the X nut on from below which is a pain because the Y screw is very much in the way. So I'm bolting it from above.
My X nut holder has a lip to hold it square, luckily I can use the mill to cut a square edge in the carriage for it to run against. Pic 1
Now some hard work. The ball nut fitting is slightly larger than the cutout in the end of the table. I know I could jiggle it over the top but it would be a pain forever more, so now I'm setting out for a jolly afternoon with files and angle grinder opening it out. Pic 2
What's the extra spigot poking up/down from the nut mount for?
After much angle grinding and filing the bed slid comfortably past the nut housing so I put in one bolt to fix it to the carriage. First pic. Not very brave but it's easier to move one misplaced hole than 4. It isn't defying gravity, there's a roller stand supporting it, makes it real easy to put on and take off.
Then the driven end, Pic 2, it sticks out a lot so I can use more of the bed, got this very wrong when I first CNC'd it so this is a slight overkill. This end is in 3 pieces, which is okay because the screw will hold it in tension with the same quarter ton I put on the Y. I plan to Loctite it in place when I drag it all together with the Bellevilles.
Then the handle end...
I haven't cut the bearing seat in the handle end yet, wanted to get my calipers on it first, Pic 3, and find out exactly how far the shaft sticks out.
Next I put that measurement in the drawing and decide how much I trim off and where. I have leeway.
The last pic was supposed to show that my single bolt went in the right place and the shaft is concentric. Would have looked a lot better if I'd put the camera a couple of inches to the left
The Y axis feels amazingly precise from a backlash point of view. The dial test gauge will reveal all.
Looking good Robin :)
I'm Looking forward to the Z axis; it's the one I've yet to figure out for my drill/mill.
X handle fitted and screw tensioned, Pic 1
An overall pic 2
I'm going to test this out before I redo the Z, see how Gary's screws perform before I buy any more.
I have to take it all apart tomorrow, add the other 3 bolts to the X nut housing, lube the slides, add some Loctite so things can't twist etc.
I'm getting a collision at either end of the X travel so I'm not quite getting quite as much as I was looking for, need to go back to the drawings for that one,
The old pulley on the X motor doesn't want to come off. Easy to shatter the magnet in an Escap Discmagnet motor if you end load the shaft, I'll have to contrive some kind of puller.
Still, not bad for one day
Incidentally, I have a new 16mm drill chuk on there, 100% better than the Warco supplied one, got it from RDG tools for £22
Hi Irving it's Morse :D
I got the lack of travel nearly sorted today by angle grinder. Tested it with a loose Gibb, lost about 1cm with a tight Gibb. Can only be a few thou left to remove think I'll leave that until I need it an extra cm. Pics attached.
THE BIG BACKLASH TEST (this being the whole point of the exercise)
Put a DTI on the bed and turned the handle, by hand. I could feel the stepper motor cogging and with the 2.5:1 reduction the slide should move .01mm per clunk, 0.0004".
Well it didn't move that far when I sat there rocking it back and forth one clunk, but it did move a little bit so backlash is now <10 microns, not bad for 20 micron nuts
I totally destroyed one of the stepper motors while trying to remove the old pulley. I was thinking to replace them anyway with some of these new fangled hybrids.
Last edited by Robin Hewitt; 11-04-2009 at 06:55 PM.
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