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3D printer build for the new space


(Matt) #1

Would anyone like to take ownership of the task of taking the round 1 TVRRUG RepRap open source kit, details here, that we were very generously donated and turning it into a working printer ready for when the space opens ?

My understanding is that the build is most of the way there, I think the electronics have to be mounted, then it needs functional testing and calibration.

(Matt) #2

Progress on the mounting of the electronics for the space’s TVRRUG Prusa 3D Printer

(Mark Hanford) #3

Nice! Be good to have a 3D printer to go with the 2.5D laser cutter :slight_smile: Then everything else can build itself.

(Matt) #4

The electronics are now operational and we’ve had a first extrusion and print.

(Matt) #5

Extruder Spring Tension Increased
The spring tension on the extruder was adjusted to be quite firm to reduce potential slippage of filament.

Faulty X-Y Driver Board
On occasions the extruder on the x-axis would stutter and miss steps, even to the extent that it sometimes reversed direction. Switching the x and y axis stepper motor connections on the board demonstrated that the problem followed the interface and not the motor. @Folknology was very kind and offered a replacement dual motor driver module from his own printer. The replacement driver module rectified the problem Open source driver board details here.

Y-Axis Linear Bearing Issues
After the electronics were mounted and a few trial prints were executed some anomalies in the movement of the heated bed ( y-axis ) were observed, it was definitely sticking in a few places.

Removing the linear rods and three bearings from the y-axis and testing them standalone revealed that they were definitely not moving freely. This was most likely due to one of two causes: the printer had been in storage for a number of years and may have been subject to some corrosion or that it had attracted dirt and dust, some of which may have come from the space rebuild.

All three of the bearings were replaced and that they ran smoothly checked, the linear rods were reinstalled and trued.

Belt tensions
Both belts were removed and the tension and alignment on the X and Y axes were adjusted to be tight and running true.

Grub screws
A number of good prints were then achieved but at some point there reappeared some inconsistencies in the geometry on a number of items. After a lot of head scratching the problem was tracked down to loose grub screws in the drive gears. These were tightened. During this investigation one of the bearings for the y-axis carriage was observed again to be exhibiting some degree of sticking, this was replaced.

X Axis Drive Gear Failure
At this point the printer was able to produce prints of several hours to a reasonable standard and good accuracy.
A problem occurred during a 6 hour print in which, 10 minutes before the end, a catastrophic slippage on the x-axis occurred. Investigation revealed that the x-axis drive gear had failed, breaking into several parts. This failure was probably attributable in some proportion to three factors: increased belt tension; tightening of the drive gear grub screw and degradation in the structure of the PLA printed gear after 4 years of ageing.

Replacement gears had already been printed and were installed and the belts retensioned. Despite several hours of experiments of shimming the x-axis stepper motor, it wasn’t possible to get the printer to operate with shedding the x-axis belt. Eventually, thanks to an idea from @Jagmills, a large diameter washer and spacer were added to the x-axis idler bearing to prevent the belt coming off.

The replacement drive gears for the x and y axes mate more securely with the T5 belts but are a slightly larger diameter than the original gears so recalibration of the x and y steps was required to ensure accurate print sizes.

(Mark Hanford) #6

So more than just “a bit of tuning” then? :slight_smile:

Good work though, it’s printing nicely now! Hopefully those old plastic parts aren’t too brittle, and ruin the effort with surprise failures.

(Malcolm Napier) #7

Whose printer is that? (Al’s?)

I would think seriously about printing a replacement part for anything that is lime green in colour and swapping it out.

Anything lime green is an original TVRRUG round 1 part printed in late 2011, early 2012. The plastic was Paul Hegarty’s first attempt at importing PLA from China (I have pictures of the wood chips included randomly in the filament as a bonus gift - so quality was anything but assured). We were hammering our printer to get everybody’s parts printed as quickly as possible. And we were learning about the best levels of infill for structural integrity. Also, it seems like the storage conditions may not have been controlled for moisture absorbtion.

So any part might fail at any time…

Those of you with Round 2 printers will have much more reliable plastic printed parts because we had leaned a lot more and the supply of plastic was to a better quality standard

In the medium term, you might want to think about upgrading the frame.

It would be helpful for TVRRUG if you went for a Mendel90 (Round 4 upgrade build). We need to document this, which Bo is working on, but I can’t mill dibond at present - which is presenting problems with launching R4.

Another alternative is a laser cut plywood frame that slots together, designed by Ian Stratford (Ginjaian) of TVRRUG and RepRapPro fame. However, you will need acces to a bigger laser cutter than you currently own to make that frame.

Finally (and maybe relevant given your challenges regarding space) you might be interested in Case-Rap. I have just pledged $40CAD for this kickstarter and am hoping to be a beta builder.

(Mark Hanford) #8

Aah, but the suspense of seeing if that 8 hour print will reach the end or not is just too exciting! And was that pinging and creaking at the end your fabulous new part popping off the bed, or one of the bearing holders splitting in two?