Aligning three-armed object

OK, I’ve hit a brick wall with this one.

I have a three-armed object which has to be aligned with rods (see screenshot) and I can’t see any way to do this. Each of the arms has holes at the ends, and the rods need to go through these holes because I need everything to line up.

Anyone have any bright ideas?

You can align the rods to the other part one by one.

Align tool as Istvan suggested.


Thank you for taking the time to reply to my question guys, but perhaps I didn’t explain the issue sufficiently.:
The rods are fix in place, and can’t move. I can align (for example) the left arm with the left rod, but when I try to align the right arm with its rod, the entire composite part moves (see screenshot). What I need is to fix the part so that it rotates around the nicely aligned hole so that when I align the right arm, the previously aligned left arm stays in place.

Some background:
This is for a three-armed bed of a 3D printer, which moves up and down on the rods. I need to check that the holes in the arms align with the fixed rods.

The best option I’ve managed to come up with is to move the centre of the move/rotate gadget to the centre of the already aligned rod, and rotate the entire bed around that point. This gives me an approximate position for the other arms. I could then simply delete the other holes and re-do them to align with the rods?

Hello RTFM,

Question. Why can you not remove the arms from the “frame”? Align the arms to the shafts and then align the frame back?


Hi.It’s not the removal of the rods from the frame. The position of the rods are part of existing geometry.

In the image, I’ve removed the holes in the remaining arms, and will recreate them around the rods. That’s probably the best idea I think

It’s a bit inexact, but you could align a single hole in the new part to the corresponding rod and then rotate the part using the center of the hole as the rotation axis. Assuming the geometry of the holes in the part exactly match the geometry of the rods, you could keep tweaking the rotation angle until you got there.

Yeah - that’s kinda what I’ve done - but it was then easy to remove the holes in the print bed, and recreate then exactly.

Hello again RTFM,

Sorry my English is not very good. Your point is very clear.

The frame, RED “X” part, is attached to your “gray arms”. You wish to align the purple rods to the existing hoes in the gray arms, yes? If your arms are not part of the RED “X” frame then you could possibly align the arms to the rods first, then align the arms and rods to the RED “X” frame?

If this doesn’t work then there “could” be something wrong with the measurements, between the purple rods and the gray arms/“X” RED frame. Misalignment?

Rule number 3: Triple check everything

Hi. I finally got it working. Everything now lines up nicely.

Thank you (and the others) for your help.


I don’t know how you did it ultimately, but in case, I share a solution I use often in this situation: create a temporary rectangular or hexagonal shape on the body you want to align and a matching shape on the fixed bodies; then align the first body using these two shapes.

The video shows it all.


That’s very clever. Shows you there’s more ways than one to skin a cat! Thank you.

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