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Printrbot PLUS V2 Build

PostPosted: 2013-Sep-Thu-00-Sep
by hal0eight
Hey guys,

Here's my plus. Mods so far -

GT2 belts/pulleys
Nophead couplers
SS M8 leadscrews
Brass nuts
Printed rod retainers
Printed filament guide
Top M8 brace
My "PrintrRail" common accessory rail system (incomplete)
Strengthened Z stop
Z stop knob
O-ring bed leveling system
Printed bed level nuts
Modded X tensioner with tension equaliser

Next mods -
Extruder head lighting
Anti-backlash gear on Z screws

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Here's the application I bought it for, making reproduction and new design horology tooling -

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Re: Printrbot PLUS V2 Build

PostPosted: 2013-Sep-Thu-09-Sep
by RetireeJay
Beautiful!

BTW, I have printed a clip-on holder for a dial indicator (viewtopic.php?f=89&t=5080) and my experiments using this indicate that there is no need for spring-loaded anti-backlash on the Z axis. The weight of the carriage is more than sufficient to "preload" the nuts and keep them seated against the top surface of the threads.

However, if you look closely at the nuts themselves when you reverse direction, you may notice them turning a bit before the wood frame captures them. So all you need to do is print a part which will couple the nut to the wood in a way that eliminates rotation of the nut. For safety's sake, I allow my nuts to back out of the wood if the head crashes into the bed before the 'bot decides to stop moving down (e.g. if the z homing switch isn't adjusted quite right). (I'd share my design, but it's really very poorly done. It works well enough for me, but I would not do it the same way now if I were doing it again.)

Re: Printrbot PLUS V2 Build

PostPosted: 2013-Sep-Mon-21-Sep
by hal0eight
Hi Jay,

Thanks for your input.

I did some more experimentation and have come to the same conclusion as you, anti-backlash not required.

I'll be adding a dial indicator soon for sure, thanks for the link to your bracket.

I've also changed the leadscrews to M6 rather than M8, which has improved side walls and any light banding yet again, I'm now getting results comparable to the Replicator at my lab, which I set as my benchmark.

I did notice some wobble from the nuts and printed a "de-coupler" that slots into those slots. This does a few things, spreads the load over a larger surface area and also means the nut now has no direct contact with the carriage, it has resulted in a small print quality increase and less margin for error.

I've now added a pretty comprehensive head lighting system which I'll get up on thingiverse soon. It's easy to make.