Distortion of igus Drylin bearings

I'm building a CoreXZ printer as designed by Nicholas Seward. A fundamental construction method is the use of nylon zip ties to fasten linear bearings to the frame.

I've obtained some sample igus RJ4JP-01-08 Drylin bearings, hoping to eliminate the rough motion and noisy movement produced by cheap LMU88 linear bearings. When I place the Drylin bearing loose on an 8mm rod, it glides as smooth as glass. (Maybe smoother. ) However, once I fasten the bearings down to the frame with zip ties, I experience a LOT of friction - I need some force to move the 8mm rods back and forth. If I install the zip ties with less tension, the bearings exhibit a lot of sloppy yaw motion in their plane of reference. I think I am distorting the bearings into an out-of-round shape.

Has anybody else noticed and solved this? I suppose I could mill some support blocks out of aluminum in order to support the bearings and keep them round. This seems like a lot of work, negating the goal of having an easy-to-build printer design. Am I using the igus bearings wrong?

Edited 1 time(s). Last edit at 07/29/2015 11:09AM by MacMarty.

My guess is the dimensions are off causing the bushings to be slightly out of place. I have had that problem more the once. You can try to clearance the mount, until they fit correctly.

At least part of that is the normal difference between bearings and bushings. Bearings are odd in that they run easier with a fair bit of load applied to them. Bushings are the opposite and have rapidly increasing friction as you apply load. So then the question becomes "do you have more load than expected"?

I got a sample of these
[www.igus.eu]
They require a press fit into a precision machined bearing holder to work, they also aren't standard LMU88 sizing
The ones you have sound much better.
[www.igus.eu]
They still require a "light press fit".
Sounds like you're squashing them out of round.

Edited 1 time(s). Last edit at 07/30/2015 07:52PM by isolt.

Igus doesn't specify what the press fit for RJ4JP-01-08 should be. I'd contact them and get the specific recommendations for this part.

I have built a machine using RJMP-01-08 and found that they can distort and bind fairly easily. They seemed to work best with a light clamp that surrounds the bearing. I think the cable tie tends to compress in one direction.

Edit: the Y carriage has igus on it secured with zip ties and they work absolutely fine.

Edited 1 time(s). Last edit at 08/03/2015 06:19PM by 3dkarma.

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Guys,

I found some "play" (increased clearance) between igus RJ4JP bearings and rods after about 9 months of (not heavy) use.
Do people using such bearings experienced similar issues?

RJMPs? suffer from the same issue?

thanks in advance!

Ivan

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The X, Y and Z axis of my build consist essentially of Igus components. At first they were fine but there is generally a lot of play in these systems which eventually causes backlash. I had these linear bushings for the Z axis but they had so much play when mounted on a 10mm smooth rod that the bushings were constantly jamming. So I replaced them with LM10UU bearings (not chinese ones) and my Z axis problems simply disappeared.

For X and Y I have used other IGUS solutions for linear motion which look perfect in theory but in practice have a lot of play. Even if ordered with "pre-tension".

So in your case I wouldn't opt for drylin bushings. Havn't tried them but I can only imagine thay have a lot of play and tend to fail under load. Just take normal old fashioned linear ball bearings or some industrial grade linear bushings if you insist on having a very quiet system. However, the price of industrial grade bushings is not to be taken lightly Doesn't mean that the igus solution is unusable, I just think that you are better off with linear ball bearings.

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Self-sourced Mendelmax 2.0-based Reprap Machine -- Ramps 1.4 & Mega 2560 -- DRV8825 (Z@1A, [email protected], [email protected], E@1A) -- genuine E3D v6 direct setup -- 350W custom silicone heated bed -- ABS 1,75mm -- Marlin 1.1.0-RC7 -- Cura 15.04.6

You can buy "industrial grade" ball bushings via ebay very cheaply. I was using Thomson Super8 1/2" ball bushings in my printer and was paying about $5 each for them, unused. There are usually a few sellers selling the things in small quantities. It may take a while for the exact size you need to show up, but they are there if you're patient enough to wait for them.

Zip ties are a terrible way to build anything, especially a precise mechanism. I tried using zip ties to adjust preload on some of those Thomson super 8s and found I could never get the tension I wanted- they were either too tight or too loose. I finally designed bearing blocks that used a screw adjustment they were perfect. I had them in my machine for a month or two before I scrapped the round rails in favor of linear guides. Check [www.thingiverse.com] and [www.thingiverse.com]

Save the zip ties for managing wires.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

the_digital_dentist, I was talking more about plain bearings. If you want a quiet plain bearing with no resistance and no play, you are going to find nothing on ebay and nothing in the $5 range. Which is why I would suggest the OP use linear ball bearings - like the ones you suggested for example. IMHO there are many good options. I would advise against drylin bushings or similar.

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Self-sourced Mendelmax 2.0-based Reprap Machine -- Ramps 1.4 & Mega 2560 -- DRV8825 (Z@1A, [email protected], [email protected], E@1A) -- genuine E3D v6 direct setup -- 350W custom silicone heated bed -- ABS 1,75mm -- Marlin 1.1.0-RC7 -- Cura 15.04.6

Thank you for your comments and hints. I'm looking for designs, ideas and components to build "the least noisy possible" printer that will substitute my current clanking prusa i3.

I know that industrial grade bearings (e.g. SKF) are in the 20-40$ price range - each.

So what to do? Choose anyway polymer bushings and change them more frequently? Cheap linear guides?

Any hint or pointer to other threads would be much appreciated! thanks and have a nice printing day!

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Disclaimer: io ce la metto tutta a darti consigli sensati, sta a te non incendiare nulla :-)
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Quote
pivan
Thank you for your comments and hints. I'm looking for designs, ideas and components to build "the least noisy possible" printer that will substitute my current clanking prusa i3.

Where's the noise coming from? The loudest thing on my Prusa-like build is the cooling fans, and it uses cheap LM8UU bearings. I have some bronze bushings to play with at some stage which look like they would be quieter, but bearing noise isn't really top of my priorities right now.

Perhaps maybe I'm not able to identify the source of the noise' it's for sure an option!

I'd prefer not to put the thread OT, anyway just to explain: my Y and X axes are quite noisy and a source of vibration. It's an I3 rework with the idlers / tensioners for the belts (gt2.5). And I currently have Igus rj4jp on both axes. Nema 17 are the classic 42byghw811 Wantai.
I understand there are some (many!) factors that can generate noise including steps (so I went for 8825 drivers at 1/32) and Vref (I keep it at about 0.7-0.8)
I'm getting quite mad on it and one of the idea is to move to a more rigid and solid structure that can guarantee parallelism and a xy mechanism (core xy probably... lot of hype indeed) to avoid the build plate back and forth movement.

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Disclaimer: io ce la metto tutta a darti consigli sensati, sta a te non incendiare nulla :-)
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Replace the ball bearings with igus bushings to see if the noise changes. However, do not leave the plastic bushings there as a permanent solution - just for testing. If the noise remains then it comes from somewhere else. What are your motors? I have simple Nema 17 motors, 1,8°, 45 Ncm running at 1/32 microstelling and they are really quiet. The loudest thing in my setup was the 30mm fan of the e3D hotend which I replaced with an ultra quiet 40mm fan.

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Self-sourced Mendelmax 2.0-based Reprap Machine -- Ramps 1.4 & Mega 2560 -- DRV8825 (Z@1A, [email protected], [email protected], E@1A) -- genuine E3D v6 direct setup -- 350W custom silicone heated bed -- ABS 1,75mm -- Marlin 1.1.0-RC7 -- Cura 15.04.6

I don't know what Igus bushings and guide rails cost, but you can buy quality, used linear guides via ebay for very reasonable prices. The last three I bought are all >600mm long and came with 1 bearing block each for an average price of $35 each, shipped. One of them was unused NOS. You won't find better bearings and fully supported rails don't flex like end supported round rails. You only need one linear guide for the X axis, so it is very compact. You can cut them to the length you need using a cutoff wheel on a grinder.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Interesting point .. unfortunately, some stuff available on ebay USA are not available in Italy/EU (or with an insane shipping cost)

I shot a very short video to explay the noise I get. [www.dropbox.com]

thank you anyway!

Edited 1 time(s). Last edit at 03/22/2016 06:35PM by pivan.

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Disclaimer: io ce la metto tutta a darti consigli sensati, sta a te non incendiare nulla :-)
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That's kinda quiet. My prusa noise is coming from the Y stepper motors and vibrating the frame and then amplified by the table top.

Once I hold my printer with hand and floating on air its quite. I haven't figured out how to float it yet on air.

Get some TPE and print vibration absorbing dampers for the feet. Works well.

Hi.. you got the point.. you've to put the largest possible amount of air between the printer and the table. I dropped down the noise to a very - unbelievable low level by putting some packaging sponge under the 4 corners.



The printer is oscillating a bit when printing.. at the beginning I thought the quality had to be lower.. however this is not true, in fact, it is better!... trust me, give it a try... it will cost nothing and its reversible in a second

Ivan

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Disclaimer: io ce la metto tutta a darti consigli sensati, sta a te non incendiare nulla :-)
CoreXY HyperCube. [www.thingiverse.com] | Cerchi test? Make: test set: [www.thingiverse.com]