TAZ Very loose Solid rod bearings?

A forum dedicated to the stock LulzBot TAZ 3D Printer
1013
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Re: TAZ Very loose Solid rod bearings?

Post by 1013 » Tue Jun 11, 2013 11:50 am

Thanks,

If new bearings from Lulzbot don't do the job. I was thinking of trying these out. http://www.realrecreationusa.com/p/10pc ... 85616.html

But at that price, they are probably not that accurate.

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Orias
Aleph Objects | LulzBot
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Re: TAZ Very loose Solid rod bearings?

Post by Orias » Tue Jun 11, 2013 12:14 pm

One thing we've tried today is loosening the double and single bearing holder on the X-carriage. Squeeze them towards each other and then tighten them back. That pushes pressure against the bearings and still allows for smooth movement.

1013
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Re: TAZ Very loose Solid rod bearings?

Post by 1013 » Tue Jun 11, 2013 4:57 pm

i will try that. it should help some

aadamson
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Re: TAZ Very loose Solid rod bearings?

Post by aadamson » Tue Jun 11, 2013 8:41 pm

You noticed that too... Mine are *extremely loose... you can rattle my X axis quite a bit. I noticed this when I went to clean the nozzle and the whole bottom of the assembly moved... granted it has a bit of weight so it doesn't move unless you try to move it, but there is lots of *slop* in the X axis bearings from what I can tell.

In looking at my 1 week old TAZ it has a double bearing on the top X rod, and a single on the bottom. Both are loose, but the bottom moreso than the top. Should the bottom bearing setup be a double as well?

And this isn't isn't the white bearing in the holder, it's the white bearing on the shaft. There is probably on the order of 1/32 or more *play* between the white *teeth* of the bearing and the rods. I looked at the top one as well and it was better, but not by much... I haven't even looked at the Z or Y axis stuff to see if they suffer from the same problem.

If the bottom of the X is supposed to be a double, how do we get another bearing?

Looks like I as well will try the squeeze test...

Alan

1013
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Re: TAZ Very loose Solid rod bearings?

Post by 1013 » Wed Jun 12, 2013 6:47 am

Tried the squeeze mod. You do have to hold the squeeze as you tighten all the bolts, but it is certainly better.

jebba
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Re: TAZ Very loose Solid rod bearings?

Post by jebba » Wed Jun 12, 2013 9:13 am

The bottom on the extruder just has one, not two, by design.

elgullitch
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Re: TAZ Very loose Solid rod bearings?

Post by elgullitch » Thu Jun 13, 2013 7:57 am

I've been getting very irregular layers and waviness in my prints. It seemed like there was excessive vibration with resonances. After reading this post, I checked my linear bearings and about half of them have the same problem discussed here. There is significant slop in two of my y-axis bearings and all three of my x-axis bearings. This seems to be a real issue -- I'm going to file a support ticket.

aadamson
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Re: TAZ Very loose Solid rod bearings?

Post by aadamson » Fri Jun 14, 2013 7:18 pm

Speculation, but if you read the data sheet these are designed as a press-to-fit part and as such the documentation says that they were will oversized in *free state*...

http://www.igus.com/wpck/default.aspx?p ... n_r_rjm_01

Quote from the datasheet
Designed as a press-fit part, it will be oversized in free-state
Might the other 10mm versions that have the same outside dimensions be a better solution and closer tolerance? I doubt much *pressing together* is going to do anything for the tolerance issue, you are just expecting that stretching those tolerances against the outside of the 2 rods will address the issue, but unfortunately, that will only occur in one dimension...

Just a thought,
Alan

1013
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Re: TAZ Very loose Solid rod bearings?

Post by 1013 » Fri Jun 14, 2013 7:25 pm

elgullitch wrote:I've been getting very irregular layers and waviness in my prints. It seemed like there was excessive vibration with resonances. After reading this post, I checked my linear bearings and about half of them have the same problem discussed here. There is significant slop in two of my y-axis bearings and all three of my x-axis bearings. This seems to be a real issue -- I'm going to file a support ticket.
check the tightness of EVERY screw....i found several that were loose. They can loosen during printing too, I would re-check them periodically too.

1013
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Re: TAZ Very loose Solid rod bearings?

Post by 1013 » Fri Jun 14, 2013 7:33 pm

aadamson wrote:Speculation, but if you read the data sheet these are designed as a press-to-fit part and as such the documentation says that they were will oversized in *free state*...

http://www.igus.com/wpck/default.aspx?p ... n_r_rjm_01

Quote from the datasheet
Designed as a press-fit part, it will be oversized in free-state
Might the other 10mm versions that have the same outside dimensions be a better solution and closer tolerance? I doubt much *pressing together* is going to do anything for the tolerance issue, you are just expecting that stretching those tolerances against the outside of the 2 rods will address the issue, but unfortunately, that will only occur in one dimension...

Just a thought,
Alan
Good catch, and that makes sense as to why they are all a little loose.

I did replace the 3 in the X-carriage with ball bearings, Since I added the extra weight of another extruder/hotend and wanted to reduce the friction. Nice and tight now. Might replace all of them with ball bearings eventually....I have noticed some hysteresis in the Z-axis, and excess friction certainly does not help that. The Y axis seems OK with these bearings though.

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