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Ultralight RepRap Y-carriage
by chowderhead, published
Inspired by the diagonal rods on my Rostock and borne by the desire to do no filament retraction, I designed this ultralight carbon fiber Y-carriage. Don't know if it'll fit on a stock Prusa, mine's pretty heavily modded.
Picture of print (from: http://www.thingiverse.com/thing:19900) shows results with XY jerk at 40 and 400 mm/s travel speed, 60mm/s print speed and ZERO retraction. Almost where I want it.
The cogs n' dogs stuff is needed (http://www.thingiverse.com/thing:26682) and I use my belt terminators which will be posted someday soon.
Given my limited understanding of the motion control in firmware, I believe the thing to alter is jerk and max acceleration, which I'll be toying with. More ideas are certainly welcome.
Print four corners, four saddles and one spacer (or print plate01.stl).
Carbon fiber rods are from http://www.goodwinds.com/merch/list.shtml?cat=carbon.pultrudedcarbon item no. 020961.
The length of the carbon fiber rods should be about 200mm, both cross and parallel rod sets. I've found that cutting the rods with a utility knife (score the rod to length then roll the rod under the blade while applying pressure) works nicely.
The last set of carbon fiber rods I received was slightly smaller diameter than the rods used to develop these stls, so there was too much clearance and I had to change the diameter in the scad script. Might want to measure the rods.
Put a M3 nut and M3x10mm screw into each corner.
Use the heated build platform circuit board to space the corners correctly:
1) Push two saddles onto a rod
2) Put one of the corners onto a corner of the board with a nut (I put the trace side up in my latest build).
3) Push one end of the rod with the two saddles on it into the corner on the board.
4) Push another corner onto the opposite end and attach it to the board.
5) Make sure it all fits nicely. If it does, remove one corner piece from the board and carefully apply a little epoxy to the ends of the rod, push the corner pieces back on and reattach the corner piece to the circuit board with a nut. Rotate the rod and move fore-aft to get the epoxy smeared around.
6) Repeat the process on the other side. Don't forget to put the saddles on first!
7) After the epoxy has set, move the saddles so that they are relatively equally spaced 1/3 the length of the rod.
8) Put the other two rods through the spacer.
9) Loosen the nuts on the corner pieces so the parallel rods can be moved some.
10) Push the cross rods into the holes on the saddles and tighten the nuts so that the whole assembly is relatively fixed to the board.
11) Finalize spacing of the saddles pushing he spacer from one side to the other. When happy with their position, apply a small dab of epoxy to each saddle/parallel rod to affix the saddle to the parallel rods. Let the epoxy set.
12) Loosen the nuts, remove the cross rod ends from the saddles and apply epoxy to the ends of the cross rods. Reinsert the cross rods into the saddles and rotate them and push them side to side to smear the epoxy. Tighten the nuts so the assembly is rigid and fixed.
13) Space the y-axis guide rods so that the saddles fit snugly on the bearings, tighten everything up, affix the bearings to the saddles with small zip ties.
14) Align the y-axis drive belt with the dog and push the belt into the dog. Move the carriage fore and aft to assure motor and idler are aligned properly and tighten everything up.
15) Experiment with acceleration, speed and jerk settings. Once everything moves like lightening and nothing skips (you'll love the whooshing noise; I do) do the retraction limbo and see how low you can go!