26 Reply by schaffe333

  • schaffe333
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Re: Bed Stability Issues.

Hi,

if you want to use 3 rods for the z-Axis you want to make 1 solid bearing and the other 2 floating bearings.

I have a strong Vibration issue on my press, if the bed is in the upper Postion. The lower the bed gets, the lesser the vibrations become. So i think the issue may be, that the bearings are 2 solid bearings. And the rods are, at least at the top near their mounting, also solid. So they might not fit 100%. The bigger the distance to the mouning, the rods can be bent by the carriage and it slides easier. My idea is to make a new carriage with linear ball bushings. One solid bushing and one floating.

And in additon strengthen the Connection between the metal and the plastic part of the bed.

27 Reply by mrallinwonder

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Re: Bed Stability Issues.

See my tldr post 15.
My vibration was caused by the bed sticking near the middle and bottom of the travel. With the threaded nut unscrewed, the bed didn't slide or drop on its own. Better grease solved it.

I agree that with 2 rods and screw rod, only one bearing can be rigid, the others must float. That means the acme nut should also float in xy, but not in z. There are other posts about this around the web, it's a tough problem.

It's possible your vibration near the top may be sticking bearings, it could also be the acme screw or nut are a bit off centre, causing a wobble.

28 Reply by jonzerb

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Re: Bed Stability Issues.

i see linear bearings are usually held in place with some C clips, does that always have to be the case of if you got the correct OD linear bearing, and drilled out the hole (if theres enough meat there to do so) and just press fit it into the plastic carriage, would that suffice?

29 Reply by jonzerb

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Re: Bed Stability Issues.

so, main issue with a linear bearing of any kind.  there isnt enough plastic in the stock carriage to drill out and plop a bearing into regardless if you wanted to or not. 

http://i39.photobucket.com/albums/e164/zerrb/20150316_170912_zpsffyydzya.jpg
http://i39.photobucket.com/albums/e164/zerrb/20150316_171118_zpsgcri9axw.jpg

30 Reply by jagowilson (edited by jagowilson 2015-03-17 00:45:48)

  • jagowilson
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Re: Bed Stability Issues.

Is it small enough that you could print a replacement? Looks very printable, and could be designed to be sturdier.

Even if it's not small enough, I would still consider a printable replacement of some kind.

31 Reply by jonzerb

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Re: Bed Stability Issues.

print the plastic carriage entirely?   too long for the 8x8 area i have with the Press, which is apart anyway, lol.  i could get a chunk of plastic though and do what i need on a mill.  i will attempt a telfon bushing first though once i get the material in the next day or two.

32 Reply by schaffe333

  • schaffe333
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Re: Bed Stability Issues.

@mrallinwonder: i already cleaned the rods and the Threaded spindle from ist original grease and supstituted with high Quality Silicon oil. It was an improvement, but didnt fix the Problem entirely.

As i am writing this, it came to mind, that i never tried moving the carriage with a loosend rod... i probably try this today.

33 Reply by mrallinwonder

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Re: Bed Stability Issues.

Printing a new 8" carriage is the width of the bed...but should fit if placed diagonally.