Printing Mini Spare Parts?

General LulzBot Mini
1

The elementary school class I gave the Mini to is excited about printing spare parts for their printer. They (and I) are total newbs at this. We have some PLA, and several rolls of HIPS. I’m going to buy one roll of ABS for the class to print the spare parts from.

I’ve heard the quality can vary among different suppliers. It looks as though the Lulzbot store only stocks Village Plastics ABS. Is that a good one to use for this? Any reason to consider another brand? Normally, we’d be pretty sensitive to cost - working on an elementary school budget here. However, since this is likely just one roll of ABS we’re buying, and since these are working parts, I’d be willing to spring for some better quality material for them to use on this, if it makes a difference. Any recommendations? (Also, if any colors are known to be more problem free, I’d appreciate hearing that.)

Also, any tips on getting these parts to print out with the best results? We seem to have the printer dialed in fairly well after it’s recent head crash into the print bed. At least things are coming out at the dimensions we specify (some holes are slightly undersize, but I guess that’s better than holes coming out oversize), things look fairly clean and have good layer and bed adhesion (though we’ve only printed with PLA so far). Should we just use one of the standard quickprint ABS profiles? If so, which one? OR might it be better to customize some settings? Do some parts (gears?) need to be printed on a higher-quality setting than others?

Any tips on post-print processing to clean things up, would also be appreciated.

I’m sure there are threads out there on this, but we’re new enough to this that we must not be searching on the right terms.

2

Villiage plastic ABS is good, I use it alot. it can be hard to get ahold of from the lulzbot store sometimes. I also use Push Plastic ABS, which comes in a 6lb roll for the same price as the 5lb one from Lulzbot, which is nice.

Colors are going to affect the print temperature. Black usually prints pretty well, as does Blue. White or Neutral can tend to need a lower temperature (white actually tends to be a pain to print all together. I think it’s the dye they use). Avoid the metallic ones for a first print, as they can tend to vary depending on what the metal flake actually is and how much heat it absorbs.

For structural parts, the ABS profiles should work, you will want to make sure that the gears and whatnot are at 85% or better infil. Measure the filliament diameter too, and if it is different than what the PLA diameter was, adjust accordingly. 3.00mm filliament varies wildly between 2.75 and 3.12mm in diameter depending on the source. Lulzbot stuff and Push plastic both seem to be pretty consistant though.

For black ABS temperatures, start with 240c for the nozzle and 105c for the bed. Also, when swirching back, be aware that ABS melts at a higher temperature than PLA, so you will need to purge the nozzle at ABS temperatures, then drop it down to PLA temperatures when you switch.

ABS is prone to lifting and warping. Keeping the bed at the correct temperature is key. Use a 5mm brim layer if possible, and if you see a part lifting, especailly the gears, it’s best to scrap the part and start again.

If you find you have trouble printing it, you can make a temporary enclosure around the mini frame using some tape and a couple of turkey roasting bags. Just make sure the electronics air intake isn’t coverd up.

As long as the bed leveling is working well and the temperature is correct, the ABS should stick to the bed just fine.

Edit: a good filliament fundraiser might be printing school logo keychain / backpack tags. Sell them for $5 each, bake sale style. If you want to post a copy of their logo (jpg, etc.) somewhere, someone might make one of those they could print.

3

I have had good luck with Matterhackers PRO ABS. Don’t bother with the lower end line they carry. I have found it to be very inconsistent quality. They are $42ish including shipping for a kilo spool of pro. That is plenty to print all of the mini’s spare parts.

4

Thanks for the replies, Piercet and Nopick. I bought them a bit of the cleaner filament. It can handle a very wide temperature range. I figured it would help them make transitions from one filament type to another. THough I’m wondering if it would be better to just have them do a cold pull when switching from one type to another?

I’m curious: Can the Min spool arm handle a 5 or 6# spool, and can the extruder unwind that weight without a problem, or do I need to respool it onto a 1 kg spool?

If I’m using the standard Quickprint profiles in Cura, should I use the “Standard” or “High Detail” (I’m assuming I don’t want to use “High Speed” for these?). Any need to slow down the print speed, or adjust other settings from the defaults for the profile? Thanks for the tip on using at least 85% infill. Makes sense (especially on the gears), but I probably wouldn’t have thought to change that.

John

5

Large spools are no problem. I run 5 pound spools all the time.

I print replacement parts with a .25mm layer thickness and 80% infill. So, probably the med. profile with the infill dialed up to 80 or 85%.

0125162019_HDR.jpg
0125162019_HDR.jpg2340×4160 1.9 MB

6

This machine seems pretty beefy. Is it necessary to print replacement parts?
Which parts should be printed?
Where do I find the .stl files to print them?

7

It depends on the usage. The extruder gears (especially the small one) are a wear part, and the small one wearing out after a year of heavy printing isn’t unheard of. Idler arms can crack, and having one crack and not having a replacement can make for a very annoying day, though you can also glue a cracked one with Plastruct Plastic Weld or Acetone. The larger gear will typically not wear for a while.

All the parts for the mini can be found in the mini section of download.lulzbot.com .

In this particular case, with a printer being used by a lot of different students with varying skill levels, having replacement parts is very important. For a home user, I would say much less important, but still a good idea.

8

OZ

My question on spare parts came from a discussion in another thread here in the Mini Hardware section entitled “Head Crash & Filament jam in new Lulzbot Mini”. This printer is in an elementary school, no matter how careful they try to be, someone is going to break something (and, as that other thread noted, it happened on the class’s first attempt to print something). I’m sure given the environment, sooner or later something else will go. I did not want them to face extended down time in the middle of a project, so I had asked in that thread if there were any spare parts people would recommend we get in. I actually bought them a spare complete toolhead assembly, as well as a spare PEI sheet (in addition to the one I used to replace their damaged sheet). Here was Piercet’s response:

And here’s the link to the current (as of the time of this writing) batch of production Mini parts:
http://download.lulzbot.com/Mini/1.01/production_parts/

Rather than continue to build on that head crash thread, which was really focused on a specific problem, I thought I’d start one about tips for printing Mini parts, since that might have more general appeal - especially to newbies like me.

9

Thanks!

10

Use plastic ABS and take time to choose what color you want to use

Is PETG acceptable for these parts?

11

It might be, the one I would avoid petg on for sure is the extruder body itself. That would benefit from a higher temperature plastic to avoid warping.

12

OK, thanks for the advice. I’ve ordered some ABS for this.

13

The PETG I have prints at ABS temps. Do some of them print lower?

PETG is very tough. We made a part at work with it that had to be removed with a punch. It took quite a beating before it broke. I wouldn’t hesitate to print printer parts with it.

14

I noticed some dust, the same color as the gear (I also use the lulzbot green filament) on the black print head parts - I’m guessing it’s from the filament but I think it’s time to print the gears just in case something happens.

Regarding the files - where can I get those? Have they been updated since 2015?

Lastly, any recommendations on printing via gcode or from .stl?

15

download.lulzbot.com is where the files are, If you are prinitng mini parts on a stock mini you can use the Gcode I typically prefer to reslice my own STL’s anyways. The dust is normal wear from the gear, you should get about 2 -3 years of heavy printing on a gear. the “must replace now” trigger is missing gear teeth.

As far as updates, there is a new Mini currently that has some extruder, carriage, idler and other miscelaneous improvements. If you are printing spare idlers, converting to that style would be reccommended, the other upgrades you would want to do on a case by case basis.

16

Thank you for the advice. I just got the mini in December. I want to print a gear to make sure I have it, just in case.

17

If you just got it, chances are it’s a 1.04. See if it looks like this one https://ohai.lulzbot.com/group/mini-v104/

18

Lulzbot’s g-codes are optimized for use with ABS. If you are printing from a stock Mini, using ABS, (and especially if - like me - you don’t yet have the experience for advanced tweaking of settings) go with the g-codes. They’ve already done a good job of tweaking settings for good results.

19

Awesome thread! I’m planning to print spare parts before I need them. I happened to find a beefed up version of the extruder idler and latch on Thingiverse: http://www.thingiverse.com/thing:1766022 I have read that this is a common failure part. I also found a filament spool bushing: http://www.thingiverse.com/thing:1353400

According to the bushing’s creator, ggrieves:

The Lulzbot Mini comes with a spool holder that’s rectangular in cross section. As the spool unwinds, it sometimes hangs, or moves abruptly. Some say that this causes intermittent tension on the extruder that can lead to wavy lines or other print artifacts.

Sounds plausible, can’t hurt to try it out.

20

THere are STLs and Gcode on Lulzbot’s site for the “beefy idler” and latch as well.