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Build Log

Makin' chips

posted Jan 4, 2017, 7:33 PM by Daniel Taylor

Pocket test

So it turns out I can feed a lot faster than I had been. That's ~94 IPM (2400 mm/min), and I think there's room for more. Pretty cool to see those chips flying.

The final dimensions of the piece (and another test I didn't catch on video) aren't quite right, so I'm trying to figure out where that error is. I feel like the machine should be able to hold a LOT better than 13 mil. Currently it looks like most of the error is in the Z axis, though that doesn't seem to account for all of it. Grr...

Because nothing says "Merry Christmas" like a flat chunk of metal

posted Dec 24, 2016, 9:53 PM by Daniel Taylor

Lots of stuff going on... I made a new sub-table to mount my t-slot table to, since of course the arbitrarily-pitched hole pattern I drilled on the previous one was completely incompatible with the table. Serves me right, I'm sure.

Anyway, I made that, mounted it, and machined it flat.

...And mounted the t-slot table on top of it:

And here everything is sitting in my shop... I got a new workbench to put things on, so it's a little less cluttered.

It was a bit of a trip getting here. I blew up my nice Geckodrives- really not sure how, but they tell me I totally fried basically everything, from a FET or two down through the entire 3V3 bus. On all of them. At the same time. I have no idea how that happened- best they can guess is a ground loop. So now I've joined the Beaglebone and the stepper PSU grounds. Haven't blown up the new drives yet!

The new drives are an all-in-one unit from Geckodrive- the G540. It even has a drive for a fourth axis! What's nice is that the pinout matches that of the Beaglebone almost exactly- I only had to remap one pin. No idea if that's intentional or not. It's ALSO good that I had the forethought to wire my steppers to DB9 connectors in the standard Geckodrive pinout, so they dropped right in with the new drives. It's like I KNEW I'd blow things up or something... mostly serendipity actually, though I'm not going to complain.

I ALSO blew up the Beaglebone. Again, not sure how. I was probing pins at the time (trying to get the new drives configured), so I probably shorted something out. Normally electronics don't straight up die from a brief short, but that's all I can figure. One of the 3V3 rails is trashed, and there's enough stuff on said rail that I didn't want to dig. Plus the regulator is a large-ish QFN in an inconvenient place, so I didn't want to replace it on the off chance it's the problem.

Anyway... ready to get back to breaking end mills! And to stop slacking on that laptop...

T-slot table!

posted Oct 6, 2016, 5:42 PM by Daniel Taylor

I got a t-slot table for the mill! It's not steel, but it's nice and flat. I'll need to drill holes to get it mounted, but it's still exciting.

No place like home

posted Jul 5, 2016, 7:39 PM by Daniel Taylor

Well, if there were a home on this machine. I got the control box wired up, though that doesn't include home or limit switches. As such, I've made it so "home" is specified in software for the moment. I'll definitely have to fix that (and the limit switches), but for doing some tests of how square things are, it's good enough. I DO have the ESTOP wired in, however.

Anyway, the pictures:

In the first image, you can see everything wired up. The steppers all have DB9 connectors on the, with the same pinout as the Gecko controllers use. Not that that's likely to become relevant, but it was as good a method of choosing pinout as any.

Anyway, you can also see the steppers mounted (left side of the right image), plus the heatsink on the outside of the box. I sanded the coating off both the inside and outside, then added thermal paste to all interfaces in an effort to get a good thermal connection. The sanding was a pain, but that's the way it goes.

The only other thing to point out is the mess of cables. In theory things will get a little cleaner when I get around to ordering the right DB25 connector- I got the wrong gender this time around. In practice... it works, so it'll probably stay like this a while.

Not pictured is the table, which finally has all of the holes tapped (I got a nice blister doing that). At least all the holes that are drilled- there are still a few more that need drilling, though if/when that happens again remains to be seen.

It's probably time to get some help moving this to the 240Vac outlet so I can do some test cuts... Well, after I drill out the final 3 holes for each of the Y axis rails. Those aren't quite aligned, so I'll just drill them out and put nuts on the back. No big deal.

Some assembly completed

posted Jun 25, 2016, 7:54 PM by Daniel Taylor

I assembled things enough to check squareness... and it looks pretty good. At least as far as I can tell without actually machining some hard material.

That said, I may or may not have broken one of my stepper drivers. Due to a wiring issue, I blew up one of the current-sense resistors (it's 0.056 ohms, so I don't know what else it would be). On the up side, I can replace that pretty easily (and DigiKey will get parts here in a couple days for a reasonable fee). On the down side, it's one more thing to do.

Next step is probably trying to wire up a 240Vac outlet. I don't have one of those here, and definitely need one before I can cut anything.

So... mechanical good, electrical still needs work. And actually the mechanical does as well (adding in two more bracing pieces on the bottom, tapping the holes in the table, putting all the screws in the Y axis rails, etc.), but it's enough to try cutting things.

Some assembly required

posted Jun 22, 2016, 8:38 PM by Daniel Taylor   [ updated Jun 25, 2016, 7:55 PM ]

I think that's the last of the parts that need to be made. A few still need some more or less minor fitting/rework, but overall it's just assembly at this point. Plus pesky details like electronics and limit switches...

Anyway, the pictures:

The back piece needs the hole for the coupling enlarged so the clamping screw doesn't catch on it, but otherwise seems to fit well. The corner supports look good.

The table also fits well somehow- I'm still amazed when that happens, despite CAD and building things via CNC. The holes/countersinks line up perfectly for the ballnut mount and linear bearings. It just needs the edges cleaned up (not technically required, except for maybe the edge by the stepper), several holes drilled (all those black X marks), and every single bloody hole tapped. Preferably actually perpendicular to the plane, unlike most of my tapping jobs...

In short: I'm super excited! So close...

X axis (mostly) assembled

posted Jun 21, 2016, 8:27 PM by Daniel Taylor

Not terribly new, but all put together:

Everything fits together really well, and it moves smoothly. I don't think there's much more I can ask for.

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.

Not as complete as it looks

posted Jun 20, 2016, 8:07 PM by Daniel Taylor   [ updated Jun 21, 2016, 11:25 AM ]

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.

10 holes/hour

posted Jun 19, 2016, 8:42 PM by Daniel Taylor

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)

Quick update

posted Jun 9, 2016, 8:32 PM by Daniel Taylor

It's late, so I'll just say that the edge pieces for my mill are done-ish (and post a picture of dubious quality). They just need holes tapped. I'm pretty pleased with how they turned out, especially given how many different times I had to clamp/unclamp the part. Miraculously enough, the relevant corner is about as square as I can measure- no play I can see with a machinists square. Yay!

Also, the X axis is more or less assembled. The Z mounting plate and leadscrew even fit on there, and seem to line up nicely. I'm always amazed when parts actually fit together.

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