Help on selecting linear bearings

Hey Guys

After successfully converting my CNC Mill to a repstrap, I now want to start building my own "real" 3D printer.
I plan the design as follows:

• (heated) bed moving on Z axis, but fixed on X/Y
• Bed starting at "highest" point and then lowering with each layer
• X/Y fixed at the top of the machine

My main goals are:

• Large print space
• quiet operation
• Reliable operation and consistent results

I am now selecting the linear bearings and rails, and am already pretty sure that I want to go for drylin bearings as they seem to be more quiet than "normal" ball bearings.
However, it seems to be a whole universe on it's own and I'm really not sure how to select between the different product lines.
I identified the drylin R, T and N series as possible candidates.
What do you think about using the N series on the Z axis (1 in each corner of the machine) and the T series on X and Y axis?

Any help yould be nice
Kind Regards
Joachim

Either Drylin or bronze bushings will give you quiet.
Check out the BB-One printer on it's use of IGUS linear rails [bbone.info]

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[www.bonkers.de]
[merlin-hotend.de]
[www.hackerspace-ffm.de]

My first attempt at a 3d printer with no previous experience on CNC machines relied entirely on IGUS products:

- drylin N for the X axis
- drylin W for the Y carriage (in my case a traditional Mendel-style moving bed)
- igubal - spherical bearings for the Z Axis

Now I have replaced all of them with traditional linear ball bearings. 95% of all the noise levels come from the motors and fans so if you are looking for a machine which is as quiet as possible you should think about ways of running the motors as quietly as possible. As far as the bearing systems are concerned: Yes, the ball bearings are louder but in my case not significantly louder. I didn't care to measure the noise levels but in both cases I do not hear the linear motion when the motors are running.

In my experience, the advantages of igus are:

- noise level (duh)
- relatively cheap
- maintenance free - no lubrication needed
- availability in EU is no problem

The reasons I switched to traditional style ball bearings are:
- the cheap and lower-grade IGUS products used for 3D printers have tremendous play. Both the N and W product lines were very disappointing to me in this respect. Even the sliding carriages which are sold as "preload" have at least 0,1mm play which resulted in deteriorating print quality.
- the sliding performance didn't quite live up to the advertised level. The movement is much smoother with ball bearings. The igubal bearings were so bad that there was a clear stick-slip effect without applying additional lubrication (I went for Krytox which solved the issue)

You should also consider that the installation of axial bearings could be tricky. They have all huge play which should be compensated by the shell the bearings are installed into. If you go for them, I would recommend buying them directly with an aluminum casing from igus.

All in all, I wouldn't use igus in a 3D printer, at least not the low-grade versions.

You could also check out Tom's review of Igus bearings and bushings.

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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

Use fully supported linear guides. Nothing compares. The motors and fans will make more noise than the bearings.

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

Quote
the_digital_dentist
The motors and fans will make more noise than the bearings.

Exactly.
You could also check for supported linear guides on ebay - there are cheap used ones. I couldn't find the proper ones for me but maybe you'd have more luck. Linear shafts with ball bearings would be second best.

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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

Hi Guys

Sorry, I forgot to mention how I want to cope with the other noisy components

• I will modify the E3D v6 hotend for watercooling
• I will use 2 50mm fans for cooling the freshly extruded filament. I hope that I can let them run at less than 50% together - reducing noise
• Decouple the stepper motors from the frame with special decouplers
• High microstepping rate

I hope this will give me a fairly quiet and smooth running machine. What do you think?
And I also forgot that I would of course buy the aluminium encased bushings.

I will look out for supported linear rails, but if you have any other comments I'll be happy to hear them.

Regards
Joachim

My thoughts on your plan:

As far as the e3d v6 is concerned, I replaced the stock 30mm fan with an ultra-quiet 40mm one. It is virtually audible at 12V and the air flow is sufficient - never had any problems with the filament expanding in the heat break. This solution is much cheaper than the water cooling concept. Last but not least, the water pump makes noises as well.

The filament fans you plan to use are probably going to get as low as 12-13 dB at 50% which is also practically inaudible. I am using two of those and they a really quiet even at 100%. I would highly recommend them before you go for some expensive ultra-quiet fans. If you don't like them it wouldn't be a great waste of money

Instead of decoupling the motors from the frame I would decouple the frame from the table/desk/workbench the 3D printer is resting on. If you use some rubber washers or other soft materials on the motor screwing points you risk introducing backlash in the system as the motor will inevitably twist in the soft rubber supports. If you place the printer on foam pads you achieve ultimately the same effect but without sacrificing stiffness.

High microstepping is generally a good idea, however, I must ask what stepper drivers you are planning to use. DRV8825 seems to be an all-time-favorite when it comes to 1/32 microstepping, but they are infamous for their moire problems and high-pitch wining noise in fast decay mode. There are solutions for this but I haven't tested them yet (waiting for parts). If you are considering these drivers make sure you read this and this.

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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

Icefire: Thanks for your reply!
Well, one advantage of watercooling would be that I could use it together with a heated chamber. But I'm not set yet and will take your solution into consideration (Maybe upgrading to water cooling at a later point?)
As I already have some silent 50mm fans, I will start with them, but your link is great (thinking about ordering some of them for another project - they are normally much more expensive! )

Decoupling the frame from the surface sounds better than decoupling the motors, it also removes complexity from the machine - thats always nice.
I'm not even at the driver-selecting point, but if you have a good proposal for drivers I will look at it (what would you recommend over the DRV8825 if I have no favorite?).

What do you think about the rails? Would you still prefer normal supported linear guides with blocks over plastic bushings?

What is this obsession with sound
your steppers singing will be loudest ?

What is all this cooling fans? How about like the good old days NO cooling

If your rig is going to be closed --- perhaps pump in chilled dry nitrogen?
or heat rejection from ammonia cooling plant could heat enclosure?

See
[forums.reprap.org]

Digital Dentist Knows

Linear rails like
[www.hiwin.com]

?drylin type T?

I suppose if you got mega $ you can get top of the line Drylin

Even cheep china rails with a ball bearing clean up will be great.

Quote
Joachim
Icefire: Thanks for your reply!
Well, one advantage of watercooling would be that I could use it together with a heated chamber. But I'm not set yet and will take your solution into consideration (Maybe upgrading to water cooling at a later point?)
As I already have some silent 50mm fans, I will start with them, but your link is great (thinking about ordering some of them for another project - they are normally much more expensive! )

Decoupling the frame from the surface sounds better than decoupling the motors, it also removes complexity from the machine - thats always nice.
I'm not even at the driver-selecting point, but if you have a good proposal for drivers I will look at it (what would you recommend over the DRV8825 if I have no favorite?).

What do you think about the rails? Would you still prefer normal supported linear guides with blocks over plastic bushings?

Unfortunately I am no electronics expert - I couldn't think of 1/32 drivers to recommend. What you could make to minimize noise is just use 1/16 microstepping with a 0.9 deg. step angle motors which is arguably more precise than a 1.8 deg. step angle motor with 1/32 microstepping anyway.
As far as the rails are concerned a fully supported traditional linear guide is IMHO definitely the way to go.

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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 run air cooling on the hot-end in my enclosed printer that gets up to about 45C when printing ABS and have neither print delamination nor extruder jams. Unless you're going to run really hot inside the printer, air cooling, even 45-50C air, should be adequate, at east for ABS.

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

Quote
Joachim
what would you recommend over the DRV8825 if I have no favorite?

The TMC2100 with 256 u-step interpolation is supposed to be very quiet. You can get them in standard module form, e.g. [www.robotdigg.com]

The TMC2660 is similar, with higher max power and SPI control, but I think at the moment they only way you can get it is on a duet wifi unless you are willing to hack up something yourself.

The biggest noise reducing measures I've had success with are tmc drivers on duet controller you literally can't hear the motors in 1/256th microstepping interpolation mode. And avoiding small fans.

Linear guide rails are quiet and almost zero play, the Chinese cheap ones work fine for 3dprinting if you give them a good clean and lube and check the bearings are all present.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

I have just replaced the LM8UU bearings on my CoreXY printer with the IGUS equivalents, and they're working extremely well - the horrible buzz I used to get from the cheap Chinese LM8UU's has now gone completely.

However - and it's a big 'however' - the IGUS bearing manufacturers have given a very high technical requirement for the holes where their bearings will fit. The tolerances around the nominal 15mm diameter are very small. In my printer, I drilled aluminium bar (aluminum for the Yanks!) to close to the final diameter, then reamed the holes out to get them properly round and within spec. This required the use of a big lathe, and quite a bit of prior experience. Just fitting them in a 3D-printed 15mm hole is unlikely to lead to success.

All I can hear now are the fans (mostly the PSU fan) and the hum of the motors.

I would check on the technical requirements for Drylin linear bearings to see if it's feasible to achieve them.

Edited 1 time(s). Last edit at 12/10/2016 11:38AM by David J.