Comments on LittleRP2 build

Forum dedicated to discussion and technical support centered around the LittleRP affordable, open source 3D resin printer.
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jon_bondy
Posts: 78
Joined: Tue Jun 16, 2015 10:55 pm
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Comments on LittleRP2 build

Postby jon_bondy » Mon Jun 05, 2017 1:58 pm

I found that tapping the plastic parts with a 3 mm tap made it much easier to mount the parts with screws. The screws are small, and it was difficult to apply enough torque to have them self-tap the plastic without stripping my allen wrench.

If you have any of the options (tall, bigger vat, etc) be sure to read all of the documentation before you start, else you will have to re-do quite a bit

Not sure why the build plate for the larger vat has 4 unused holes along the outside. Not sure whether the mounting holes in the larger build late could affect print adhesion. Would it make sense to just use a 1/2" chunk of aluminum and avoid the plastic part entirely?

The lead screw on the LittleRP2 is much tighter than on the original LittleRP. Is this to be expected, or do I have something mis-aligned or is a screw too tight?

Are there new procedures for how to use the LittleRP2 (for example, how to set up the Z zero switch)?

goopyplastic
Posts: 236
Joined: Sat Mar 29, 2014 6:16 pm
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Re: Comments on LittleRP2 build

Postby goopyplastic » Mon Jun 05, 2017 8:01 pm

If you have a 3mm tap, it is helpful. I tried to go inbetween too tight to thread but not loose enough that it would cause a problem over time. There is a small chamfer that will let it seat flush even after self-tapping creates a ridge.

Originally the build plates were meant to be modular, with 3 different sizes. And you could just remove the plate and swap for a smaller size. I think the build plate would need to be 3/4" thick or more to not need the plastic part and it just seemed excessive. An option I didn't explore was to have an attachable rim above the plate that is flush with the perimeter of the plate, you could use the 4 threaded holes to attach this. Another reason for 1/4" is that it is more self-source friendly.

The 4 corner holes shouldn't affect printing, and are there so you can attach different subplates. The original idea was being able to attach an acrylic plate that would be disposable. The resin would effectively weld to the acrylic plate, so this option is for people who absolutely don't want a print to separate from the build plate during printing. Another option was a perforated plate that screwed in with 4 corner spacers.

The leadscrews should be similar tightness, however it should loosen up.

The Z limit switch is not actively used, rather included if someone had a use case. (Vat with no underplate, homing after print etc.)

jon_bondy
Posts: 78
Joined: Tue Jun 16, 2015 10:55 pm
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Re: Comments on LittleRP2 build

Postby jon_bondy » Thu Jun 08, 2017 6:01 pm

Thanks!

If the leadscrew IS noticeably tighter, what are the best things to check first?

goopyplastic
Posts: 236
Joined: Sat Mar 29, 2014 6:16 pm
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Re: Comments on LittleRP2 build

Postby goopyplastic » Thu Jun 08, 2017 6:20 pm

the antibacklash nut has 2 threaded portions, if you separate the pieces and try threading each of the parts onto the threaded rod separately, are either tight, is one / both tight? Assuming the tightness isn't from an alignment problem and just the threads are tight they should loosen up in use. A tight or loose thread shouldn't affect printing as the spring in the antibacklash nut is what maintains consistent layer thickness. The nuts can be worn out almost to the point where the threads are barely engaging and should still function properly. I noticed on some of the ab nuts that the small threaded top piece took a bit more force to insert into the brass housing and did not slide as freely once inside.

There is also some variability into how much the spring is compressed before both threaded parts are threaded onto leadscrew. If the spring is more compressed, it will be tighter on the leadscrew.


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