Servo upgrade and replace

IMG_3007 IMG_3005Ok, we tried using a new servo to handle raising and lowering the carriange platform. The original  one didn’t have the strength to suspend the drill when it wasn’t being raised, and that made it occasionally just drop. I ordered a stronger servo and installed it, however while it was strong enough to hold the drill at height, it wasn’t “accurate” at positioning. I don’t know if there was supposed to be a different library, or if the code needed to be changed, but the resolution of the placement was sometimes one click for a motion, and sometimes it moved two clicks instead. Since this sets the depth of the cut, that doesn’t make me comfortable. Lee and I have been also considering getting a “follower” to be installed at the cutter head – this lets us just drop the carriage to the follower, which would slide on the blank and manage the cutter depth – but we’re not there yet

So after fooling around with that for a while, LeeIMG_3008 came up with an approach to use another stepper  motor to rotate the carriage shaft, and rather than using a servo arm on a motor mounted to the  carriage, the stepper was mounted to the housing, and a cam shape was cut from plastic, glued
together and slid onto another steel rod. To make it easy, the rod used is another pen mandrel rod,  so the size and shape are easy to rely on.

In the process Lee made some redesigns to the motor placement, first the motor for the carriage lift was on the left side of the box, but then he re-arranged the placement of the motors on the right side, so that all the motors could be located there (and the wiring would be all in on location). After that was in place we started to play again and finally decided to try to double the resolution of the patterns for designs that were not simply linears.

IMG_3010When doing a spiral or straight line, the speeds can move things along in a nice line. When I was trying to do the zig-zag/sine-wave approach, unless I was using only a single 1:1 ratio for side to side and up and down, the pattern started to look more like an 8-bit pixelated pattern. So to increase the resolution for that pixelation we upgraded the drive motors from 200 step to 400 step motors. They’re installed now, and we’re working to see if we can get the designs more smooth.

1 thought on “Servo upgrade and replace

  1. Pingback: Servo upgrade and replace | Brian's Workbench

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