Jiggle in gantry

This topic contains 3 replies, has 2 voices, and was last updated by  Tim 2 months, 3 weeks ago.

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  • #94266

    Dave S
    Participant

    I have my machine up and running (thanks for putting together such a great kit/design!).   While it seems to be working well, I noticed have a loose bearing connection on one of the gantry rails.  It jiggles a little when I push on the top of the z-axis rails.  It does not seem to effect accuracy or machining wood pieces.  I was wondering if it is critical to eliminate the play, especially if I want to machine harder materials.  If so what bolts would I need to adjust?  At moment everything is square.  The image shows the bearings that seem to not be in direct contact.

    Thansk in advance.

    #94268

    Tim
    Participant

    To get that particular bearing in contact you would tighten #4 (I found that once I looked at the design and really thought about it the whole tensioning thing made a lot more sense–Think about it, if you tighten bolt #4 it will squeeze the circle of bearings tighter around the conduit). However even with bolt #4 all the way loose you should really have contact with all 3 of those bearings.

    I had the same problem when I was first assembling my machine. When you were assembling and you put the bolts in their holes, did they go in freely or did you have to sort of thread them into the holes?

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    #94271

    Dave S
    Participant

    Thanks for the rapid reply.  In many cases I could not get the bolts thru the holes. Often my printer left me with slightly undersized holes so I was used to it.    I used a 5/16 drill bit to chase the holes where that was the case.  I don’t recall having loose bolts but definitely was able to assemble without threading them in.   I’ll try tightening the bolt up and see if it improves.  I thought that would be the case, but I did not want to mess with my squareness.   Think the slight looseness will result in chatter problems cutting aluminum?

    #94296

    Tim
    Participant

    Thanks for the rapid reply. In many cases I could not get the bolts thru the holes. Often my printer left me with slightly undersized holes so I was used to it. I used a 5/16 drill bit to chase the holes where that was the case. I don’t recall having loose bolts but definitely was able to assemble without threading them in. I’ll try tightening the bolt up and see if it improves. I thought that would be the case, but I did not want to mess with my squareness. Think the slight looseness will result in chatter problems cutting aluminum?

    In my opinion any looseness should be addressed. If you can move it by hand it will give room for the endmill to chatter.

    IMO I find z axis perpendicularity more important than 100% squareness (if your Z isn’t perpendicular you can tell by looking, if your machine isn’t 100% square you can’t tell by lookng) but you should be able to adjust so all bearings touch + you have squareness.

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