Summary

180+ degree rotational wrist mod for Anar's Solid CAD InMoov Forearm

Instructions

I'll add more detailed instructions later...
rotawrist2_180 replaces Anar's rotawrist2 file, the rest are new.

Print out:

(1) l_rotawrist2
(1) l_wristsensorbracketv2
(1) wristgears3a_sensorV2
(1) wristgears3a_sensorkeyV2
Buy at least two of these: TRIMMER 5K OHM 0.5W PC PIN
http://www.digikey.com/product-search/en?KeyWords=3339P-502LF-ND&WT.z_header=search_go

for sensorkeyV2, you have two options, this is a really really small part.

option1: (printed but haven't tried) print out the wristgears3a_sensorkeyv2 using an SLA printer, like a form1. check www.makexyz.com for local makers that can print this out for you.
option2: (verified but tricky) print out wristgears3a_sensorkey_blank, and carve out the cross pattern with a sharp mini exacto blade. I did this as a test. it definitely works, but be very careful!
option3: (unverified) make a small amount of thick acetone slurry, print out sensor_blank, stuff acetone slurry into philips slot of trimmer pot, center sensor_blank and press onto slot, let slurry dry and cure for at least 24 hours, carefully remove and clean (plastics on trimmer pot do not react with acetone)

Drill out the sensorbracket with a 5/16 bit. the trimmer pot must slide freely for calibration.

The cross feature of sensorkey must fit snugly, but not forcefully in the trimmer pot. trim and file to suit.

The sensorkey must fit with a bit of play in it. maybe 0.1ish mm per side. it must be able to settle in a bit to mate with the trimmer pot.

Disassemble the servo, and attach the external pot in a manner similar to that used for the inmoov bicep, shoulder etc.

Assemble rotawrist2:

place wristgears3b in rotawrist
place sensorkey in sensor gear
place sensorgear in rotawrist
screw in wristsensorbracket
program arduino to activate servo to 90 degrees
adjust trimmer pot to where it's centered and the servo stops moving.
adjust wristgears3b to angle you want when input is 90 degrees
carefully place pot in sensorbracket, and push down until you can feel it engage with the sensorkey
carefully rotate pot back and forth until you get zero movement at 9 degrees
tighten pot set screw
*adjust minpulse and max pulse so wrist only turns 180 degrees. otherwise it will make several rotations. my values were 1200 and 1765. that way I can send straight 0 to 180 degree commands.
assemble rest of forearm
*enjoy!
Tips for tightening tendons
- When assembling hand to wrist, string up tendons in the palm up position
Instructions assume that 0 degrees is palm up, 180 degrees is palm down
Instructions assume that for the fingers, 0 degrees is open, 180 degrees is closed
Move Wrist servo to 140 degrees
Set each finger servo to 40 degrees
wire up each open finger tendon and close finger tendon, not loose but doesn't have to be tight
using this setup, I have full range of motion in the wrist, and full range for each finger
try not to get in the habit of just slamming the finger servos to 0 and 180 degrees. They'll do it in most wrist positions, but they will be too tight to reach wrist 0 and wrist 180. I think the range I'm using is 30 degrees open, 140 degrees closed.
be aware that as you approach 0 and 180 for the wrist, you will not
This is compatible with the newest version of wristgears3b and wristlargev4 and cableholderwristv4, although you will need to cut away part of cabelwristholder so as not to interfere with the wrist sensor assembly

2014-10-25 - updated wristgears_sensor to v2, beefed up the gear horn to it prints better

InMoov 180 degree rotational wrist mod for Anar's Solid CAD Forearm