Oval circles help!

[tim_146]

Hello great minds! I have the dual CTC printer and im wanting to know why I’m getting Oval circles instead of perfect ones, so my supposedly all in one movable designs like spanners and gears etc fuse together thus not moving and the circles being Oval. Ive printed a circle and the 20+20mm test cube and it looks like the y Axis front to back is printing 1mm more than the x left to right. So I’m getting a 20+21mm cube and also 1mm more one way on my circles making it Oval. Can anyone help please thank you so much

[Nebbian]

Adjust your Y axis steps/mm down by 5%.

[tim_146]

Hiya

ive just tried 5% 10% and 20% on my y axis and printed the helper disk large and I cannot notice any difference its still showing as 1mm over on one axis, I changed these settings under the makerware software device preferences under Axis steps mm.

Any more suggestions? thank you for your help

[MadBuggyofDoom]

Square the axis’ up, ditch the spring tensioners and tighten the belts.

[tim_146]

You may be right, ive looked at the left to right metal bars and the both look bent in the middle a tad, also the back one move a fair bit left to right when moved by hand looks like they are not fully in right on the bearings, ive removed the tensioner springs already and belts are OK not overly tight, but I think ill buy 2x 5mm bars and convert to metal pulling and try to clamp them so they are true. When I push the carriage manually front to back there seems to be loose and tight areas so not moving smoothly. They should run smooth shouldn’t they? Also when I do buy the (I believe) 5mm rods do I have to get 5mm inner diameter pullies or do I go for 6mm? Thank you

[ronaldor]

Usually it is a physical problem. For example, the hotend is not firmly attached to the X-axis. Tighten the screws.

[tim_146]

Hi, I’ve check this and it is all tight Any other problems?

[tim_146]

I thought to strip one end down of the printer to see what state the rods were in and sure enough Chinese special bad workmanship came to light. The carriage rods gears were not aligned so moved them to be perfect where the belts now move perpendicular with each other ive levelled out the washers so they don’t move from side to side now and managed to level out the whole carriage level by grabbing opposite end and bending diagonally so it aligned better. All put back together and now have perfect circles. Thanks for all ya help

[protrade]

Hi tim_146,

I have exactly the same problem with oval circles.

I have manage to calibrate my ctc to print decent layers and have overall very good print quality. It’s just scaling I am fighting with. Tried the steps per mm in MakerWare but seams to give no change.

Can you give more details on what exactly have you corrected in the CTC?

P.S. I have also noticed some loose and tight areas when moving the Y axis.

How exactly accurate is your printer. Can you keep dimensions down to 0.05 mm ?

Cheers, Peter