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PLA Cube Gears for Replicator 2

by whpthomas, published

PLA Cube Gears for Replicator 2 by whpthomas Dec 21, 2012

Description

Many of us have been frustrated to discover that the pins for emmett's Screwless Cube Gears are not PLA compatible. They are too stiff, and in my experience, attempting to force them in can crack the pins and damage the piece itself.

So I set about trying to design some alternative pins for PLA. My first attempt was to make flexible end tabs, but while this worked, the cube gear axle is too short to support this approach. In the next attempt, I altered the internal structure of the tip of the pin to make it more flexible for PLA and redesigned the protrusions.

These new pins were designed using an ACIS solid in Shark FX (sfx file included) so will behave well with Makerware, ReplicatorG and skeinforge. They snap into place with moderate force and rotate freely.

Recent Comments

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I made one version in white PLA at 100% and one in trans orange at 150%. Both worked really well, especially the larger one, which wrong together much easier, and turns with much less effort.
Did you use the same dimensions as emmits gear cube?
So I just need to print PLA-cube-gears-plate-1 and 2 correct?

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Instructions

PINS ONLY

If you have already made Emmett's Screwless Cube Gears, then these pins are a drop in replacement. Simply download and print PLA-gear-cube-pins.stl file - that's all you need.

If you are using Makerware I would recommend at least a 0.2mm layer height, 3 shells and 15% infill. In ReplicatorG I am doing the same, but using the skin module to achieve a 0.1 mm outer surface finish.

CUBE GEAR PLATES

If you want to make the PLA cube gears from scratch, simply download and print the two plates: PLA-gear-cube-plate1.stl and PLA-gear-cube-plate2.stl. The first plate includes my snap off ear raft print aids, to increase the surface area of the small gears to prevent them from breaking loose during printing.

Again, if you are using Makerware I would recommend at least a 0.2mm layer height, 3 shells and 15% infill. In ReplicatorG I am doing the same, but using the skin module to achieve a 0.1 mm outer surface finish.

BTW: The print in the photo was made with Makerware (default medium settings) and printed on my Replicator 2 the first day after it arrived - the original pins broke, hence the new PLA design.

I made one version in white PLA at 100% and one in trans orange at 150%. Both worked really well, especially the larger one, which wrong together much easier, and turns with much less effort.
Did you use the same dimensions as emmits gear cube?
So I just need to print PLA-cube-gears-plate-1 and 2 correct?
Love this!!! Printed mine in RED PLA and all of the pieces just snapped together. No other finishing required at all. Done on a MendelMax 1.5
Can you add the gear files not all on one plate so I can print each item separately. I would like to print each part a different color.
Great! When you say "at least" 0.2 mm. Do you mean a minimum of 0.2 mm, that is 0.2 mm an upwards, or do you mean "at least" as fine as 0.2 mm (in effect 0.2 mm an downwards).

Regards

- Björn
I printed this on a Up! Plus in pla. The pins work perfect! Only one weird thing, the corners of the big gears, the highst point of the print, did not print completly. In other words the highst layers of the model did not print.

I have never had this with other prints. I noticed when you open the STL in netfabb you see a thin line at top of the corners of the big gears. This is exactly the place where my top layers did not print. So I guess this is an error in the stl?
Could you upload a new stl with 1 seperate big gear cornerpiece?
Just click on the link to Emmet's original thingiverse.com/thing:10483 in the above right hand menu under "derived from" - you can download the individual pieces from there.
Screwless Cube Gears
by emmett
Which files are they? And also, are all those pieces compatible with the PLA pins you have here?
Thanx! By the way, I figured the problem of my unfinished print was not your STL. I've just started printing PLA and I think the PLA formed a clog so it stopped extruding at the end of the print.
The core is a truncated tetrahedron.
I printed with the given settings and natural PLA on a Replicator 2, and found it was much easier to assemble and operate with small blasts of silicon oil applied (I did the same thing when I printed the Makerbolt).

This is such a cool design! This is one of the first designs I saw that made me really want a printer.
The plate and pin files worked just fine for me! Had to use pliers but the fit was firm and positive. Printed in PLA (3 color changes) on a Replicator, 10% infill, 1 shell, 0.27mm layers with skin enabled. Came out great! See the patriotic picture to the left.
Like the print Darrell, the colour change is really cool!
These pins still aren't working for me. They will hardly fit into the holes, even after scaling down and once they are in they certainly won't turn. Is this a sign that the other pieces are printed poorly or that my printer isn't calibrated as well as it should be?

I really like this model and it seems pretty straightforward, but nothing is fitting together for me. Any help would be appreciated.
Sorry Alex, I am away from my computer and trying to post form my iPad, and somehow I ended up mixing up my posts.

In response to your problems, I have found that you really need to print with at least a 0.2 layer height. If this is no good, try slowing down your print speed to 40/80. Particularly for the pins. They really need to look like the black ones I printed in the picture. If they do, then just work them in. You may find that the holes are slightly oval, so the pins may only go in with the flat sides facing the narrow. then if you can get the pins in, turning the gears will burr the oval holes round, but only if there is enough play to get them to turn. Sorry you are having problems, my first cube pictured was just the default medium settings in makerware with a 0.2 layer height.
Thank you for the help. I will keep playing around with them and see if I can it to work.
Love the print Alex, the colour change is great!
Thanks! Printing the pins from this thing to use with the gears I printed from the original screwless cube. Everything has been scaled up by 125%, but the pins don't seem long enough. My cube keeps popping apart because the pins barely protrude from the gears themselves.

Note my printer is a home made prusa mendel i2 with no HBP so I'm using PLA exclusively. At least these pins fit nicer than the original pins, shame they aren't long enough, i'll try reprinting and stretching in the X axis to see if that helps
I have made two of these, both without scaling and the pins worked fine for me. I used a 1:1 copy of the original pins dimensions, so I have no idea why they didn't work for you - other than maybe the scale you used was different to what you remember.
Hmm, Like i said, I did scale all parts by 1.25. However, did you modify the scale from Emmett's screwless model? It seems like they aren't long enough. I will experiment and report back.

I'm absolutely sure the scale is the root cause my issue, that, and my loose, uncalibrated printer is probably the real reason.
Might you have downloaded the PLA heart pins I made and got them mixed up with the PLA cube pins - the heart pins are shorter and would create the problem you are describing.
Yes! Thats probably what i did
I've never tried the gear cubes in PLA, but now that you have these pins I think it would be great to have a translucent green one in PLA. Thanks!
Interesting idea on the pin structure!

Just recently I had experimented with making a belt-clip that would not damage pajamas (long story). After a few iterations, the golden recipe for both strength and flexibility was to make sure the entire clip was two nozzle-widths wide so that no fill was needed (a wide test print without fill proved to still be rigid, but terribly brittle).

Hopefully I'll upload the design soon along with the whole goldilocks-lineup.
As you point out the earlier pin experiment used a 2 skin wide flexible tab. They needed to be 0.5mm wide and have a 0.5mm gap between them and other surfaces to work. Much less than that and the gap would bridge and it wouldn't work well. It actually amazed me that I could print a flexible mechanical clip that small. Very interesting experiment nonetheless - an approach that may come in handy in the future.
Its basically a parabola cutout on the inside, and an oval cutout on the outside with constant curves to smooth the edges. Seems to provide just enough flex while still maintaining the strength.
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