RepRapPro, can't align y-axis rods.

I'm assembling a reprappro, mono mendel, and I'm having trouble getting the two y axis rods to line up parallel. I'm on the step where I place the glass on top of the two y-rods to test for a gap. (Step 5 of http://www.reprappro.com/documentation/RepRapPro_Tricolour_frame_assembly#Aligning_the_frame). There is a gap, and so the glass plate wobbles when I press on the corners. I've confirmed the glass is flat, and also wobbles in the same direction no matter which orientation I put it down, so it's the y rods that are misaligned.

I'm trying to follow the instructions this site has provided for fixing it, but it's not helping. Nor do I see how it would help. The 4 feet of my frame sit flat upon a level surface, so there is no rocking there. This guide suggests to place a shim under one foot to get the y rods to level. This doesn't work. if I start stacking pieces of paper under one foot, it just causes the whole frame to tilt, including the y rod I'm trying to affect. Am I mis-reading this? Is there another way to get the y rods to level?

All other measurements are spot on. The sides of each triangle measure to 290mm, and all bars connecting two triangles are 273. The only way I can think of to fix this, as a last resort, is to modify one of the U clamps so that one of the the y-rod sits higher/lower within it at one end. Is this a good idea? I'd rather the solution be that I'm just missing something that's more appropriate.

I'd check a couple of things:

1) is everything supposed to be a bit loose when you are doing this? It sounds like you are trying to shift rods to get everything to line up.You only tighten everything after step 8.
2) Is there anything hanging up the rods in the printed parts? That something I've run into a lot of times. Not all printed holes are full sized.
3) Did you get a bent rod? Stuff like that does happen.
4) Are you adjusting the upper rods to square things up? That's about the only part they haven't been very clear about.

Bob

I sympathize with you Drangid - that problem is just one of the things I dislike about that method of construction. I would put a sack of spuds on the top of the frame before I did final tightening!
Anyway, if everything is spot on as you suggested, my solution would be to enlarge the hole in the foot (crossmember hole) and use the increased clearance to lock the threaded shaft higher or lower as needed - use washers of course.

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Waitaki 3D Printer

Hmm, yes somewhere along the way I thought I was to tighten the bolts. My problem with these instructions is several times so far they specifically say "do not tighten these bolts yet," but they never follow it up with a later instruction to finally tighten them yet give evidence that they should be.

I loosened all the nuts, but that didn't releave any tension that was causing the misalignment. However, I did notice that the cross bars weren't tight in their holes. They could wiggle up and down, and if I pulled the two opposite corners up, the glass layed flat on the bars. So I re-tightened the cross bars while pulling up on them, and that seems to have levelled it.

glad you got it flattened out