Need Help!- one axis smooth the other not so

[GeeksGoneBad]

Hey guys - I cut out a part from plastic (King Starboard to be exact) and my Y axis walls are perfect, byt my x axis are like scalloped - hopefully you can see it in the picture

what would cause something like this?

I programmed depth cuts of .02 with a .25" bit and even did a finishing pass at .05" - was a brand new bit too

thanks for any ideas!

Jamie

[SORCHEROR]

first tell us what machine your using?also check your x axis gibbs,if you have ways,maybe
loose,that would be my guess,or maybe a binding problem,in any case we need more facts

[SORCHEROR]

ok,i see your machine on your website,do you have ballscrews or lead screws?and which axis are you refering to as the x axis?the long axis i assume?

[SORCHEROR]

i see you have wire cables running around pulleys,i bet they are cauing some binding in the axis,just a guess,what is there purpose,to keep tension on everything?or is it to minimize backlash?

[GeeksGoneBad]

I have Acme 1/2"-10 leadscrews with homemade delrin nuts

when the router is traveling on the shorter axis is when I get the rough sides - and actually I've removed the cables (which were to prevent racking and worked quite well) after some modifications I've made - there are no pictures yet of those mods up on my site - but basically I'm using better bearings on all axis and also a steel bar across the bottom with bolts all the way through (instead of the t-slot connections that I find are kind weak)

[LeeWay]

I would think that is either racking or flex in the Z axis or gantry. Was this cut at a slow speed or feed?
If so, you might try speeding up the cut to see if it makes a difference. If not, then try a slower cut.

[GeeksGoneBad]

yep I tried a few different feeds and speeds - the slowest my router will go is about 8000 rpm and I started at 6ipm and all the way to 30 ipm with no difference - I also tried a faster RPM on the router at the different feeds with no difference either

I will try some tests to see if it's racking - I know I have just a little bit across the gantry but I was thinking that wouldn't affect a cut going across - but I will clamp that sucker down and see if that removes the scallops... if it is then I'll just reinstall the cables and pulleys (pocket door tech)