CNC Mill >
Not terribly new, but all put together:Nothing else today was terribly picturesque- mostly just marking hole locations for the cross braces on the under side of the base. It's probably overly-optimistic, but I'm hoping to get the final few pieces machined tomorrow. Then drilling out some holes to allow things to fit better (namely the side plates), and I'm well on my way to being able to hook up some electronics.
I got enough pieces done enough that I wanted to stick things more or less together. Here's the result:
The "full assembly" there isn't quite as close to complete as it looks. The gantry is held on by only a few screws, since they don't entirely line up. Not sure what's crooked, but something sure is. The sides are also only loosely held. The rails need a couple more holes tapped/screws put in. And so on.
Still, only some 4 pieces left to machine (well, 6 pieces, but 4 of them are half-done, so I'll call it 4). Plus fitting, of course, which probably means drilling out some holes to accommodate my crooked tapping, and hitting some crooked gantry supports with the belt sander.
The only really "new" thing to be seen (aside from things being assembled) is the channel cut on the table. That should allow the ballnut to move without grating on the bottom.
Or thereabouts. Seems a little unreasonable when put in those terms, but that also included machining edges, aligning everything (multiple times), and more. On the up side, the base is more or less done! Mostly what's left is to machine the channel in the middle so the ballnut has some clearance. That didn't get done today because the chunk of metal is warped, and I'd rather like that area to be planar with the rest of it. Anyway, the idea is that the linear rails and the supports on the bottom should hold it pretty flat.(Also pictured are the new ginormous linear rails. They could probably use a little grease, but otherwise seem fantastic)
There's a big step- the Z axis is fully(ish) assembled! At least all the hard parts (ie, the ballscrew is secured and going through the carriage). I made a small mistake, and need to drill a hole up top so I can tighten the coupling onto the leadscrew, but that's not terribly difficult nor requiring precision. There leadscrew also isn't quite centered in the axis, so I need to machine out the mounting holes for the stepper plate a bit so it can float into the right position. Again, no big deal.
Overall I'm happy. The plate to attach it to the X axis is "done"- all the holes are cut, the relevant surfaces machined flat, and the cutout for the leadscrew mounting block has been made. All that needs to be done on it is to cut it down to the right size- it currently has an extra ~inch on one side...
Anyway, things are still coming together- now I just need to tap a bunch of holes, and machine some giant plates for the main structure of the machine. And then probably spend far too long re-aligning things to get them as close to square as possible.
Speaking of the ballnut... that had to be reversed on the ballscrew. Now, I know there are ball bearings in there, so I was being smart, and turned a piece that would fit on the end of the ballscrew to keep the balls inside while I twisted the nut off. That... didn't work. Somehow the balls got out of their tracks anyway. Fortunately they were covered in grease, and many tedious minutes later I had them stuck back in the right place
After screwing up a couple things, the Z axis is mostly done. I got the front milled flat to accept the new spindle adapter place, a hole bored through it for the leadscrew, and a cutout (plus mounting holes) for the ballnut. Oh, and a place for the bearing beneath it, of course. One little piece needs to be fabbed yet (a bearing clamp for the top side of the leadscrew), and some holes need to be tapped, but otherwise it's basically set.A couple things really went wrong when doing this work. First, the cutout for the ballnut was too big- I screwed up the gcode offsets. Anyway, that meant that the six mounting holes for the ballnut couldn't be drilled. So... with some help and the use of a press, a new chunk of metal was machined to size and pressed in the hole. Then I drilled the holes, and machined the ballnut cavity to the proper size. There shouldn't be a lot of force on those screws (the flange is at the bottom of the carriage), so I think it's all good.
One more piece- this time the mounting plate to attach the Z axis to the X axis rails. It came out... hopefully OK. The part shifted a bit while trying to elongate the holes on the lower right. And of course I screwed up the gcode and forgot to drill the other holes (leftmost) before that. I think I got it realigned (ie, they should be square to the rest of the holes), but who knows. At least the rightmost holes are non-critical. I was hoping the left holes would be a good alignment reference, but it's not the end of the world if I need to drill one of them out a hair. I'd rather not, but that's the way it goes.
Fortunately everything else came out well enough. The edges need to be trimmed a bit, and there's a pocket on the back that still needs to be cut, but it's getting there.
Anyway, it's progress, with some frustration. On the up side, I think there's only somewhere in the mid-teens of parts left to machine...
Long story short, those holes will need to be drilled out, and I'll just stick nuts on the back side. Fortunately I can do that with these holes, and haven't tapped any other M5 holes yet. Which is really good, since most of those are blind, and I really couldn't recover from having the wrong threads in them. M5-0.9 screws are nearly impossible to find, and stupidly expensive (like $2/screw), so that's not really an option.
Back to the drilled/tapped holes on the gantry... evidently an M5-0.9 tap is a thing, and I have one (the "normal" M5 thread is M5-0.8). As far as I can tell, it was only ever used on some pre-1972 cars. And when I went to the hardware store and asked for a normal M5 tap, that's what I got. I'm really no sure why they even had one in the first place, and I probably should have double-checked the taps before I left, since the guy fishing them out for me didn't seem terribly with it.
A whole batch of new parts. The big one (literally and metaphorically) is the gantry. It's been squared up to the right length and had holes drilled (and tapped). More on that in a bit.The second-largest part is the plate that the Z axis stepper sits on. And the little parts are shims to go on the leadscrews. The bearings I got are shorter than the non-threaded portion of the leadscrews, so in order to clamp down on them, I need a shim in there. That's what all the little round things are. Strictly speaking, I really have no reason to need to do anything to the ends of the leadscrews, since they're going to be held in place by the bearings (which will be clamped at either end, so the leadscrew can't slide anywhere). It's more a matter of principle... And I already got the (oddly-sized) nuts for it, so I might as well.
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