SoliForum - 3D Printing Community — Bed Stability Issues.

Re: Bed Stability Issues.

null@example.com (mrallinwonder) — Tue, 17 Mar 2015 11:53:20 +0000

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

Re: Bed Stability Issues.

null@example.com (schaffe333) — Tue, 17 Mar 2015 11:09:58 +0000

@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.

Re: Bed Stability Issues.

null@example.com (jonzerb) — Tue, 17 Mar 2015 01:17:59 +0000

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.

Re: Bed Stability Issues.

null@example.com (jagowilson) — Tue, 17 Mar 2015 00:40:39 +0000

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.

Re: Bed Stability Issues.

null@example.com (jonzerb) — Mon, 16 Mar 2015 22:48:43 +0000

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.

Re: Bed Stability Issues.

null@example.com (jonzerb) — Mon, 16 Mar 2015 22:13:45 +0000

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?

Re: Bed Stability Issues.

null@example.com (mrallinwonder) — Mon, 16 Mar 2015 15:07:49 +0000

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.

Re: Bed Stability Issues.

null@example.com (schaffe333) — Mon, 16 Mar 2015 09:35:09 +0000

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.

Re: Bed Stability Issues.

null@example.com (mrallinwonder) — Mon, 16 Mar 2015 04:18:06 +0000

I tried a quick front stabilizer, it made no difference, that fixes any side to side wobble, not the sticking/vibration issue.
The problem is the weight of the long bed puts a lot of force on 4 very small contact patches in the bed bearing:
At the top at the back
At the bottom in the front

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Quick fix for me was clean out the old grease, stuff those grooves with a grease designed for high pressure. Had to try 2 different lubes.
I have thought about printing a new plastic part, 2 choices
4 linear bearings in the obvious 2 holes or
Leave the plastic hole pretty much as it is, but add 4 normal ball bearings that press the rod where the >> are above - if they can move they can level the bed as well

My thought about linear bearings is they need to be loosely held, maybe in thick grease in a slightly larger hole - if they are rigid the system might bind. Also there is then no side to side slop for the z screw. 3 rods all in rigid bearings ain't good. Ideas?

Re: Bed Stability Issues.

null@example.com (trayracing) — Mon, 16 Mar 2015 02:50:53 +0000

Why not just make a new carriage? That would allow you to make it easily levelable as well, and have pockets for the bearings. (A lot of designs seem to use zip ties to hold them in place, at least for x&y).

I'd be worried that drilling out the exisiting carriage would weaken it too much. I've yet to find anything overbuilt on this box.

Re: Bed Stability Issues.

null@example.com (jonzerb) — Mon, 16 Mar 2015 01:37:08 +0000

Bearings would be much harder to pull off given the design of the carriage, since they need c clips to hold them in and all. Also, as you said, the whole thing with needing to possibly replace the rods with bearings, I'd prefer to not deal with.

Re: Bed Stability Issues.

null@example.com (trayracing) — Mon, 16 Mar 2015 01:22:07 +0000

Most bushings have some stiction. If you're going to the trouble, why not upgrade to LM*UU bearings? You might eventually need to replace the rods though. Head on over to reprap.org for bushing&bearing opinions.

Re: Bed Stability Issues.

null@example.com (jonzerb) — Sun, 15 Mar 2015 23:17:56 +0000

So. Would something like this be worthwhile for us with the Press?

Also. What material would be the best if I wanted to make some flanged bushings that would slide into the holes in the z axis carriage here? I was going to drill the holes out a bit to get the bore in them smooth, then turn a few flanged bushings in the lathe so they are a press fit.

Re: Bed Stability Issues.

null@example.com (Skyblue) — Thu, 12 Mar 2015 23:16:33 +0000

selkess wrote:

Skyblue wrote:
First thing I did when I received my Press was to wipe off the thick lithium grease they applied to all moving surfaces. Then applied light machine oil (3 in 1). Machine is much smoother than it was at first, as it would hardly move. Don't forget to oil the z rod also. I don't know if this will void their "warranty", but at this point, I don't care.

Do you realy know why they have litium in first place ? its because we dont have any metal bearings or bushing. its all plastic exapt for z brass thing..
i if apply light oil then need know that its not harming the plastic parts lithium is good for plastic
some oils can harm plastic we have metal rods and plastic carriges only.
i use lithium grease only
"there is no plastic or metal bearings/bushing on x y" !!!!

Yeah, I've been using machine oil on my SD3 for 3 years, no change in plastic. Using it on my Press now with no noticeable change. I don't think it will harm it in my lifetime. If you are worried about preserving your machine forever, go ahead and use the thick crap. If it was a Lambo, I would agree with you, but at this price, nah.

Re: Bed Stability Issues.

null@example.com (selkess) — Thu, 12 Mar 2015 10:26:46 +0000

Skyblue wrote:

First thing I did when I received my Press was to wipe off the thick lithium grease they applied to all moving surfaces. Then applied light machine oil (3 in 1). Machine is much smoother than it was at first, as it would hardly move. Don't forget to oil the z rod also. I don't know if this will void their "warranty", but at this point, I don't care.

Do you realy know why they have litium in first place ? its because we dont have any metal bearings or bushing. its all plastic exapt for z brass thing..

i if apply light oil then need know that its not harming the plastic parts lithium is good for plastic

some oils can harm plastic we have metal rods and plastic carriges only.
i use lithium grease only

"there is no plastic or metal bearings/bushing on x y" !!!!