Shifted Layers on gear print

I have a repstrap that I built myself, and it uses a gearbox for the Y axis. My prints aren't terrible, however they are shifted along the y axis. I was wondering if anyone has any ideas on how to fix it. I'm kinda thinking its something to do with the gears/belt.

perhaps a gear is slipping, or motors need more current. there is also the possibility because of the gear reduction that the motors are not able to keep up with the torque needed for the speed they are running. there is a curve where the faster the motor goes or the step rate is the lower the motors torque. to test this print at half the speed you are printing at now, and see if there still is an issue. if there is then consider an alternate gear ratio structure to the y axis, perhaps use the on that is specified in the manual.

Edited 1 time(s). Last edit at 02/26/2013 10:08PM by jamesdanielv.

Thanks for the reply, I think I've solved it due to your reply in another post! I believe the motor was overheated and missing steps in one direction where there is more friction.

If anyone is interested in checking my repstrap out......... it's not pretty but it does work.

[www.youtube.com]

i think it is awesome you are using your own custom electronics design! i saw a few home-brewed boards in the video. what stepper drivers are you using?

Edited 2 time(s). Last edit at 03/01/2013 03:22AM by jamesdanielv.

I'm using the L297/L298 combo, because of the low cost.

I used these for the L298
[dx.com]

and I bought 5x L297's on ebay from china for less than $6 shipped.

In hindsight if I were going to do it again, I would roll my own big board and have it professionally made......... as you can see, there are A LOT of wires. I went with the L298 boards because they have the diodes, board, L298, heatsink, etc. However if you buy this board, you will need to add a filter cap and preferably a bigger electrolytic on both the motor (12 or whatever you chose) and ic supplies (5V), because there are none and all the electrical noise will cause strange things to happen/ not happen.

The board with the micro is very simple. I chose an 18.432 mhz crystal to insure comms are as error free as possible. Check out http://www.wormfood.net/avrbaudcalc.php The atmega328 does not use an arduino bootloader, I have a $7 programmer from ebay I use. Works well.