Monday, 26 August 2013

Trim a toe and hack a heel...

I took the extruder block home and sliced a piece off the rear end, so now it doesn't hit the base of the Z stage any more. But when testing that, it turned out that at a specific X stage position, a screw in the Y stage would hit the extruder holder. 'Tis but plexiglas, I can take a wirecutter to it and snip off a corner. Works.

The lower Z endstop is not calibrated for the current height at all. Need to add a better-than-cardboard piece. Unfortunately, it's in a very tight spot -- that's one of the issues with this design: While the printing surface is nice and accessible, the L- and U-shaped aluminium pieces and the multiple layers of plexiglas makes it difficult to get in and adjust things.

Finally after some fiddling got it bolted on - though a broken-off corner on the teflon runner foot -- only in that corner, of course -- made the endstop plate bend forward, so I had to bend it back. Fiddly.

The endstops don't work the way I'd hoped to. At the moment, they seem to be floating, though the bottom Z LED registers nicely, and the bottom X LED registers weakly.

Oh. I had old pin settings on them. After fixing that, it turns out the two Z endstops and the two loose ones are fine, but the X and Y endstops are floating. I wonder if it's a problem with the mounting? Will take one off and try it on its own. Yes, definitely the case for the X endstop. I guess the bits of wire on the back side were enough to dig through the paint and short it. Adding a piece of cardboard helped quite a bit.

I'm also getting a bit concerned about the X and Y stage rail pressors. The X stage wobbles sideways quite a bit, and the Y stage jumps easily up and down. Not easy to fix, particularly the Y stage, due to the construction.

Trying the ReplicatorG calibration block. It seems to expect much higher speeds than I have given in the firmware settings. I should re-measure the speed and put in realistic rates. 4mm/sec is kinda low.

Here's some of the bits I chipped off today and the precision tool I used for it:

Monday, 5 August 2013

Crashing the Teacup

Wired the Arduino back up after last time's oscilloscope adventures. Testing first with G1 [XYZE]nn commands, only X works. With homebrew firmware, the extruder works as well.

Giving G1 E10, the extruder motor starts chopping angrily. Setting a search speed (despite the lack of real "search" capability) it moved nicely for a bit, then went back to angry chopping. Trying to adjust the potentiometer does nothing. Odd. Adjusting the potentiometer while it's running a simple back-and-forth doesn't change anything, have to turn it off and on. After adjusting, it now runs stably from Teacup, though slowly and noisily.

D'oh. Simple but consistent miswiring. Green is step (go), yellow is dir (change). Not sure why the Teacup movement is so slow. Using the G0 commands it goes zippy-fast, actually too fast for Y and Z. Setting the max feedrate for all down to 226 from 500 helped the Z, but Y is still unhappy. E is now doing fine.

M104 S100 sets the target temperature to 100ºC. M105 shows that the temperature is going up! It went 5º over before it stopped cooling. Excellent!

Crashed the Z head into the bearing holding the rod. Annoyingly, the extruder house also hits the bearing and supports, after I carefully filed parts of the underlying plate. Need to slice 4cm x 3mm off that, too. Not tonight.

The crashed head: