Rattling sound

Hello all,

since yesterday or the day before that, I am hearing strange rattling sounds while printing.
I checkd the scres/washers, nothing seems to be loose. Could it be the bearings? Is it going to be a problem?
Please see the attached audio file, I recorded it while printing the bottom infill so you can seperate printer noise from the rattling.

thanks for advice.

I think I have exactly the same sound as you and I think I know why but haven't tried to fix it yet because I'm having too much fun playing with the printer. I have not fitted the fan and the screws that are sitting loose in the X-carriage are loose and vibrating. They are making noise. Maybe you have the same situation?

I wish I had epoxied those nuts into the X-carriage during the build. I have no urge to disassemble that now.

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Garry Bartsch
I wish I had epoxied those nuts into the X-carriage during the build. I have no urge to disassemble that now.

You can use a pair of long-nose pliers behind the hex screw head and washer to ease the nut forward into the trap while you turn the hex screw with an Allen Key. Tighten the screw just enough to allow the fan casing to slide in behind the washer and you are done. No need to disassemble the carriage.

Regards,
Neil Darlow

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I try to write with consideration for all nationalities. Please let me know if something is unclear.
Printing with Mendel90 from fedora 25 using Cura, FreeCAD, MeshLab, OpenSCAD, Skeinforge and Slic3r tools.

nope, I have a fan equipped and that is not the sound i am hearing.
it occurs only when the Y axis moves.
since this evening it seems i have similar sounds when the x axis moves, so i guess it are the linear bearings.
should i ry to oil the smooth rods?
any ideas?

You can check if the bearings are noisy by moving the carriage manually with power off or motors disabled. It should be evident if there is a problem. Applying a little engine oil to the smooth rods is recommended by nophead.

Regards,
Neil Darlow

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I try to write with consideration for all nationalities. Please let me know if something is unclear.
Printing with Mendel90 from fedora 25 using Cura, FreeCAD, MeshLab, OpenSCAD, Skeinforge and Slic3r tools.

I've had a similar problem on the y axis, except I'm not sure if I'd describe it as rattling. More like a soft scratching. Oiling the rods with WD40 fixed it.

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neildarlow

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Garry Bartsch
I wish I had epoxied those nuts into the X-carriage during the build. I have no urge to disassemble that now.

You can use a pair of long-nose pliers behind the hex screw head and washer to ease the nut forward into the trap while you turn the hex screw with an Allen Key. Tighten the screw just enough to allow the fan casing to slide in behind the washer and you are done. No need to disassemble the carriage.

Thanks, that's a good way to do it. Because I'm still wanting to see the print as best as possible (thus not using the fan yet) I had thought to do a similar thing (pull the screws forward and thus the nuts into the traps) and the squeeze some Sticky-Tack into the gap between the screw head/washer and the carriage. This would be fast and easy to remove later when it was time to use the fan.

I got machine oil and tried to oil the bearings/smooth rods, but there seems to be a oil seal on each side of the bearings preventing the oil to get inside.
any advice?

I just put a drop oil on the bars very occasionally. Some bearings make a noise but it doesn't seem to affect the prints at all so I ignore it.

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[www.hydraraptor.blogspot.com]

After re-checking that all the fixings in the X carriage area were tight I still have the gentle rattle. I can reproduce it to a lesser degree when sliding the X carriage manually. It's as though one of the tiny bearings in the linear bearing is rattling lose inside it.

Aside from liking a perfectly smoothly running machine I wish it wasn't there because sometimes cracking or similar sounds are emitted when prints are failing in various ways and the rattle is confusing the ability to identify this. I guess the solution would be to replace a bearing but I'm not up to that yet. The prints are unaffected as far as I can see.

Even with oiling the rattling is getting louder and louder.
Since today, when moving the Y bed by hand, I can feel slight resistance moving it along the axis. I think the bearings start to fail.

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muelli
Even with oiling the rattling is getting louder and louder.
Since today, when moving the Y bed by hand, I can feel slight resistance moving it along the axis. I think the bearings start to fail.

I'm just wondering how the bearings are doing? Did you replace them? Mine are noisy too and the Y bearings started to drag heavily till I oiled the rods. They are OK now but noisy. I'd like to have these silent for reasons I mentioned above. All the bearings I have found online seem to be about the same price and from China. Apparently there are high quality Japanese ones but I haven't seen how to buy them yet. eBay doesn't seem to have them either.

I don't think they will ever be silent looking at how they work. At any one time half of the balls recirculate in a clearance channel so they have the potential to rattle. They then have to squeeze into the gap between the rod and the sleeve which takes some force as there is a negative clearance to get pre-load. That is why they feel lumpy in movement. All the balls rub against each other, unlike a rotary bearing where they are separated by a cage, which I presume gives the friction and scraping noise.

Perhaps packing them with some form of grease would make the quiet but when I have put grease on rods it went gummy and caused them to seize up.

For silent low friction running you can use bushings but they have clearance rather than pre-load so will always have some slop allowing the carriages to run off.

The original Sells Mendel was quiet and very low friction as it used rotary bearings. The downside was it was a lot more complicated to assembly and adjust.

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[www.hydraraptor.blogspot.com]

No, I still have not changed them, I baulk the trouble in replacing them :/
I already got new ones, but these are also the common "08/15" ones (german saying for very cheap and common things *g*) and not very high grade.....

I got some 12mm bearings for my new big printer to be and they seem much smoother than the 8mm. Rods and bearings to up the Y carriage to 12mm would cost about GBP14 from
[www.zappautomation.co.uk]

Be aware that Zapp's rods are not the correct tolerance spec for linear bearings. I think they are g6 instead of h6, which means they are undersized and hence feel more free. I use h6 rods and the bearings are G6 meaning they are undersized to give pre-load. Without pre-load any wear allows slop. With pre-load you don't get slop until you hit a threshold in wear. The downside is more friction.

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[www.hydraraptor.blogspot.com]

So if I use the 12mm rods and bearings I got from them will I get a lot of slop or a teeny bit?

I think it depends on where they are in the tolerance band. Have a look at the definitions of h6, g6 and G6. AFAIK h6 is the correct spec to work with linear bearings.

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[www.hydraraptor.blogspot.com]

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muelli
No, I still have not changed them, I baulk the trouble in replacing them :/
I already got new ones, but these are also the common "08/15" ones (german saying for very cheap and common things *g*) and not very high grade.....

I looked at all the RepRap stores I could find and the bearings were similarly priced. Then I looked on eBay for ones that looked the same. I bought a set and will inspect them when they arrive (it's been weeks already but with cheap shipping this is normal) to see if they are the same as the original. But I'm like you; I don't want to replace them and after Chris' comments there seems no need to.

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nophead
AFAIK h6 is the correct spec to work with linear bearings.

Would all bushing manufacturers make their linear bearings the same size? Using their bearings, Misumi USA recommends their rods, "hardened with g6 tolerance" (Misumi Linear Bushing PDF) Would this not be too loose? Or might their bearings be tighter than some other brands? Might their bearings be designed specifically for their rods? And in this case, a perfect match?

Seems odd to me that the page is both about "linear bushings" and "linear ball bushings", which I would call linear bearings. You would expect that the clearance / fit for bushings would be different to bearings unless the nominal sizes are adjusted to take pre-load into account before tolerance is applied.

One would have to assume they know the correct size rods for their bearings. They don't explicitly state the tolerance but the diagram shows them to be h6, (which is odd for a hole tolerance), whereas LM8UU bearings are normally stated as G6, which is a clearance hole against h6 but I assume it is not quoted against 8mm but 8mm - pre-load. To be honest I don't really know. If you are going to buy from them you could ask them to explain.

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[www.hydraraptor.blogspot.com]

It is confusing me so, yes, I had better ask them before buying so I understand what I'm getting. Thanks Chris.