soft-robotics:molds:hitodama-arm
Table of Contents
Hitodama's Arm
Checklist for mold
Step 1
Metal rod is an exact half circleHeight and diameter of rod are rounded to the half of millimeter (Something like .4 might be harder to lathe?)Base of mold allows for the placement of jumper cables in step2, so that they are free to exit to the bodyTarget silicone thickness is 1mm all around.4mm injection hole, with some extra space for the 'umbilical cord'4mm Bubble blow hole at the highest spot, when tilting the mold in injection.Bubble blow hole has a leading funnelSilicone flow is smooth and round all the way to the bubble hole with some extra material forming the 'umbilical cord' before the blow holeRound side of mold contains coils that look just like the coils of the neck sausagePieces can be aligned to the accuracy of 0.1mmPieces can hold together while holding the mold in the air and tilting it (or let's build a ramp like Kari's? ^^)Outer piece has a draft for easy release of top from basebase remains attached to rod during step 2, but can be removed after and the rod can be pulled out
Step 2
Box can contain and protect the end of 6 jumper cables while casting, so that in end we're left with a hole for the sensor and 6 ends of jumper cablesIs the Box milled? Printed? How is attached the the outer piece?- sensor should be around the middle of the palm.
Matti's point - the jumper cables should be a bit loose to make sure they don't create tension on the sensor when bending.Target silicone thickness is 1mm all around, but there is a 1mm of extra at the flat end to accommodate the fabric and cables4mm injection hole, with some extra space for the 'umbilical cord'4mm Bubble blow hole at the highest spot, when tilting the mold in injection.Silicone flow is smooth and round all the way to the bubble hole with some extra material forming the 'umbilical cord' before the blow holePieces can hold together while holding the mold in the air and tilting itOuter piece has a draft for easy release of top from basemetal rod can be pulled out after casting
Changes made to model for milling
- Smooth edges of bottom to top alignment notches.
- Add 'mickey mouse ears' to the dent that houses the metal rod.
- Remove injection hole.
Fixes checklist
Fix bumps in the wrist that caused holes in the skin<del>Wider tunnels and exhaust holes for bubbles on the arm (Didn't some of them feel too small?)</del> Exhaust PoolsWider tunnel for the injection port on the arm (We had a collision with the remains of the umbilical cord)The fix that we had to do manually for the sensor box, there was a problem with height? Make sure everything works together on first tryAny fix necessary to make sure the wires can pass through the bottom when doing step 2, instead of from the side which caused all of the leakage.Apply any remaining Fillets from the 'mill' model version, such as the mickey mouse ears and the smooth alignment notches.Make sure that after step 2, all of the wires will be completely immersed in silicone, isolated. including the tips that go into the sensorProduce the mirrored arm.Box tolerance offsets.
- Step1 outer - One corner of one of the notches is missing a fillet
- Step1 outer - The bottom of the mold should be "full" so the stock doesn't need to be milled from both sides
Step2 outer - Fillet the edges of the pool
Optional fixes
- Find a better sealant than Plastecine?
- Can the bottom part support 're-skinning' the arm? after gluing the inflation tube it's impossible to put the arm back into the bottom mold. Probably a hole for the tube is also not enough, because of the glue that is around the tube for fixing it (Unfortunately still using that rather ad-hoc method of fixing the tube). But maybe the bottom part could be a hole all the way through? in that way it _should_ be possible to squeeze it inside for re-skinning?
Lessons learned from 1st prototype
- Avoid any possible dirt/was residue on the 1st stage mold. how to make sure the wax is super clean?
- Work in a more sterile environment.
- Don't use copper wires. Are the silver ones oxidizing?
- Knit the wires into this net fabric instead of the hell that I did last time.
- Should be more careful when removing the rod. Why actually didn't I do this?
- DON'T USE anything oil based to clean the silicone. Soap should work?
- A better sealant than the Plasticine?
- Fillet the metal rod/s + Also top and bottom
- Milling patterns for skin like? Wax?
soft-robotics/molds/hitodama-arm.txt · Last modified: 2019/08/13 20:32 by avnerus
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