Y - Carriage rattles in one direction

Hi,


I am wondering if anyone has had this experience. I have a problem my PRT 4g with the Y-Carriage is rattling and a little bumpy in one direction. The move/cut speed between 1-3 ips, this seems to happen mainly on the Y=48" end when it turns back heads back toward the Y=0" end. It happens for the first 10"-12" and sometimes again more or less in the middle.

The pinions are fairly new and tight, the rack is clean, motor springs 3 1/2 turns, the motors do have a little slop, it cuts accurately square.

I have also noticed that my radius cuts are choppy when heading back down toward 0" along the Y axis. This will be a problem if I am to perform for a project cutting shapes out of 1/8" HDPE.

As I puzzled about it last night I wondered if the Y-Car is out of square. The only thing I could think of is that the motor side of the Y carriage is leading when going from 0-48 then when going from 48-0 the passive side of the carraige would be leading but being pushed by the motor side it could be binding slighty???

Today I checked the Y-Carriage and it is out of square about 1/16" in the direction as I imagined.
So tomorrow I will square up the Y-Carriage But I not sure if it will fix things. My Bot is about 7 years old with moderate use. Maybe it has several issues with parts wearing out.

If any one has any insite I would be greatful.

Thanks, Robert

Check to make sure your rails are parallel. I setup a PRT 48 Standard and before we adjusted everything the X gantry was very rough running when it approached one end. When we started tweaking we discovered a slight bow in the rail on one end leading out almost 1/16". We fixed that and all was good.

You might also check your V rollers, make sure they are not binding and rubbing instead of rolling.

/RB

RB,
Thanks for your reply and suggestions.
I just finished running 2 ea 1/8" sheets double taped together and my results are mixed from good to bad and a few terrible spots. Like you mentioned I did notice the the y- gantry is worse on the 48 end and the x-gantry is worse on the 96 end. With all combined most but not all of the diagonal cuts were bad, some radius cuts were good but more were bad, and every once in a while a bad nick. Today I adjusted the y- gantry
but it might actually be slightly worse than yesterday.

I marked out all of the bad areas so I could study their relationship to different areas on the table. I am wondering if I start from the ground up would a whole new rack & pinion need to be considered?

Thanks, Robert

At one point when I had a PRT96 either my v rollers became loose or my z rail had worn. I had to tighten up the rollers...just throwing the idea out there.