Squaring - tension bolts and their axis

I was wondering if someone can tell me wich tension bolt is for wich

axis. And how much degree can you fix?

[attachment file=48290]

My base is set square in all dims. The gantry with its X and Y axis

is not parallel to the base axis. So I unscrewed the motormount X2

and Y2 to have these to axis fix on one side but moving on the other.

Then loosened all other tensionbolts.

From the corners I measured on the rails and placed cableties wich stop

the rollers, on the other side I added clamps, they really dont stay in place well

(so change is noticed easy).

Measuring the X and Y gantry axis it looks square. Putting slight tension on the

Tensionbolts and locking the roller mounts again. Still square!

Removing clamps and cableties it jumps into the crooked parallelogram again.

The rails are straight.



Use it for a while to “break it in” then rebuild the center. For some reason this seems to work for people having a stubborn build. Also with zero tension on any tension bolt you should be really close. If you are not you should have a look at your printer and check for accurate dimensions and axis perpendicularity, most printers print at an angle on one or more axis because most people will never notice. There is not even a way to adjust it out until the newest marlin firmware that can do it digitally. For most these are the first dimensionally critical parts they have made.

As for which bolt does what. Start with all tension bolts loose and tension one set and check to see how it moved. It should only take one or two sets, if you are tensioning them all you are fighting the opposite tension bolt.

It also looks like you might have used something other than PLA? PETG and ABS tends to be too flexible to tension much it just stretches. and if you mixed materials they have different shrink rates and could also be causing issues.


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Everything was printed in abs but the motor mounts and the Z motor mount.

I am sure they came out of the printer correct as I also controlled angles on the big parts.

I will try to compensate somehow and run it for some time

Running the cnc with a pen i ran into another issue:

The motormounts Y1+2 tend to jiggle around. Moving them for

an inch left then right they really move around a lot (against the moving direction).

Is that one of the flex issues Ryan just mentioned?

No. That sounds like miswired steppers.

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indeed! a single one came loose

Some of us run a small zip tie through the middle of the stepper connectors to tie them together. I used a piece of half inch heat shrink to keep them together.