Drylin W Rails

Hi All,

Curious to hear about others experience with Drylin W Y rails -- what to expect and what I might be doing wrong in setting mine up.


I've got a (mostly self-sourced) MendelMax that I'm working on getting together. After looking at the different Y axis options I figured I'd go with the Drylin W.

I picked up the rail & blocks from Igus based on the released BOMs and got the carriage & heater from MakersToolWorks.

I'm guessing I must be assembling things wrong, or have something else not quite right -- with the heated bed mounted I'm not able to get anywhere near the expected speeds (nor anywhere near the speeds I was getting on a Prusa I2 with a not-quite-as-heavy bed but significantly less powerful motor). Basically not able to get much past 100mm/s, using a 4.5Kg-cm motor / 40 tooth pulley (i'll replace with a 5.5Kg-cm soon, but I don't expect that to change things to get them up to expected speed).

I've tried re-assembling the carriage on the cars using both MTW's instructions (squeezing cars lightly together) & Igus' instructions (putting 11N+ downward force during assembly).

Also, I know MTW uses different, light-colored liners for their blocks; the blocks on the BOM come with darker colored liners -- not sure if the liners might be the difference… or if some break-in is required?


Would love to hear what kinds of speeds others are getting, and any thoughts on what i might be doing wrong -- thanks!

Think I found my issue; i'd read a couple of installation instructions for similar products & I'd connected the belt in the simplest fashion to the belt attachment piece (the MTW instructions have the belt overlapping)… due to side effects of how my belt was stretching, the belt was causing the carriage to twist in a way that was causing much more friction than it should have.

Now for basic tests I've got it running -- seemingly reliably -- at 500mm/sec without skipping any steps. Hopefully it'll stay that way when i get to printing

You could use smaller pulleys to get higher torque, and increased resolution, but they will obviously reduce your top speed.

I'll be curious to see how you make out with these, as I have been considering them for my MendelMax, which currently uses 10mm rods for the Y axis.

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Mike Anton
[manton.ca]
[laserlight.wikidot.com]

So far my experience has been pretty mixed.

I did put in a 20 tooth pulley - and with the steppers I'm using am actually able to get pretty fast speeds (though i still need to turn down my jerk settings; I can move well at 500mm/sec when manually jogging about, but on longer prints I will get skipping; mostly doing things <100mm/sec printing still).

I spent a lot of time trying to get the cars riding at just the right angle - since putting in the screws also torques the cars, it's somewhat maddening to try and get right. Going by the MTW instructions I ended up generally getting the cars too tight and having too much friction. I tried placing the whole thing in a 4" mill vise, that I barely tightened with the blocks inside the jaws (to maintain alignment) while I put in the screws… but I was never able to get things quite right; when everything felt great, I'd take it out of the vise and the cars would push out just a bit and grab the inside of the rail. In some cases adding the belt clamp would pull 2 of them back down… but often with some misalignment, and often causing interference with the other 2 cars.

Right now things are working reasonably OK, but I feel like I just ended up loosening things to the point that there's a bit of extra slop. Prints look pretty good - and layers are stacking up nicely, but getting a lot of ringing artifacts. That may or may not have some connection to the looseness.

How tight are your belts? If they are too loose it will contribute to ringing, though ringing is also a functions of moving mass and available torque.

What microstepping are you running? I thought Arduinos topped out at stepping rates around 30kHz, so I have the upper limit on mine set to 300mm/s, with 20 tooth pulleys. Your acceleration setting will also determine if you have skipping problems.

I run my MendelMax which uses a solid 3mm thick 237x237mm chuck of aluminum used as a bed support, at up to 300mm/s, with 2100 acceleration, though I haven't tried pushing this faster. But, this is using hardened rods, and linear bearings. My standard rapid speed is 180mm, but I'll often manually double the printing speed, and don't run into any problems. On a very rare occasion, with a small infill movement, I'll get a skipped step, but this is so rare now, that I probably haven't seen this in over 6 months. I'm running a Kysan 54Ncm motor on my Y, but a 17HS6002-N27B 64Ncm motor from robotdigg.com on my X (which I highly recommend, and they are cheap). If I had room, I would put the higher torque motor on my Y as well.

What are the cars mounted to? A few pictures might help us see what might be going on.

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Mike Anton
[manton.ca]
[laserlight.wikidot.com]

Hi,

Sorry for long delay (have had a lot of non-reprap things to attend to)… I'm pretty bad at getting pictures & even worse at uploading them… but have sorted out a number (most?) of my issues, though of course it's an ongoing game of whack-a-mole

Re: steppers -- I'm currently using these 62 oz-in motors (43 Nm cm)
[www.automationtechnologiesinc.com]

The RobotDigg ones look nice, though their shipping costs are quite high (and i somewhat doubt the A4988 drivers would actually hit near full power on them)… Also they don't give specs on inductance, or a power curve so it's hard to tell how power would fall off with speed with them -- high torque motors pretty much always have high inductance that causes the torque curve to fall off much faster with speed. Though I've no doubt it's working great for you

Cars are mounted as per instructions -- i bought a complete build plate & Y axis from Makerstoolworks (sans rail / cars which I bought directly from Igus based on the published BOM). I killed the rubber washers that came with the kit (as they didn't give any screw torque guidelines and things seemed loose)… though there was a note in their instructions mentioning that not everyone finds the rubber washers to be helpful so I figured it was fine.


I'm at 16 microsteps. I believe the Marlin firmware now will do multiple steps in one interrupt to account for stepping rate, but may be wrong on that. I'm mostly running at ~200mm/S traverse moves and ~60-95mm/s printing though.



Anyhow, things are mostly working now (though still have some minor waviness that I think is due to lead screw mounting needing some tweaking, and still a little ringing).

Most of my skipping, etc. issues seem to be due to 2 things:

- belt rubbing pulley edge (I'd dialed things in initially, but as things settled the Y belt wandered a bit); some tweaking with an industrial sized ziptie & a bearing have helped align the motor & sorted that out in the short term - longer term I'll be installing a printed bearing shaft support… the standard MM 1.5 Y mount doesn't really support the motor well enough to keep it from rotating slightly under load (and the tensioning Y idler tends to also rotate to one side or the other when belts are tight).

- Overhangs curling a bit, causing head to crash into them on taller builds -- I've been doing a fair number of structural parts with high infill (and often solid), so when there's curling it can get to be a pretty big obstacle. Still sorting this out -- printing in ABS so general consensus seems to be never to use a fan (and other folks say it means need to print hotter -- which I'm pretty sure isn't the case with my setup). I have enclosed the printer in clear PEVA shower curtain (cut to size & these: [www.thingiverse.com] work great to attach; just hold the shower curtain plastic on to the frame & attach the anchor; no need for the actual zip tie) so have a well contained heated build.



I've also moved to a belt-driven extruder which has been great for cleaning up edges in most cases -- I'm still sorting out some issues with my hobbed (er, knurled) bolt not lining up quite right with the plastic but otherwise it's been fantastic.


Back to the Y rail… in general it seems pretty decent now, and when things are happy I'm generally getting really quite good prints. I don't know that they are any better than rods though -- I think they are quite a bit better than 8mm rods (as I had on my previous Prusa i2) but I'd expect 10mm rods to be pretty comparable and less finicky - though not sure. The Makerstoolworks Y axis kit I have mixed feelings about; adjusting it is a pain, esp. with the adjustments requiring accessing below the build plate with both an allen wrench & a spanner / crescent wrench… and I've managed to strip one of the aluminum build plate mounts while doing adjustments -- not a huge deal as I just put a nut onto the mounting screw, but it means it's less easy to adjust now. The placement of the belt mount, being off center, causes the bed to raise slightly at one end or the other when doing high accelerations… and the way the belt attaches makes it easy to get off center. So basically it seems to take a lot of dialing in, but after the work good things come out. I'm slowly trying to work through and friendly-ify the printer though as I have time, and make it require less love to get things back up quickly after doing maintenance.

I think you are correct that Marlin does multiple steps per interrupt, but I was still under the impression that it was limited to about 300mm/s. I've never pushed it higher than this though, so perhaps I am mistaken.

You could try lowering your acceleration to see if the ringing is minimized.

I would be surprised if a belt rubbing on a pulley would cause your steppers to skip. There really isn't much friction there, since the pulley is moving at the same speed as the belt, unless you have static washers on either side of the pulley.

You are right about the Y-axis motor support. I machined one out of a piece of extruded aluminum. Now I can run the belts so tight that the shaft on the stepper motor starts to bend. I guess I need to add a bearing support for the other end of the shaft. Someday I'll get around to doing it. I also use an 8mm bore pulley, a shaft, and a couple of 608zz bearings for the idler pulley on the other side, which prevents having to flip the belt, or run the teeth over a bearing, which I never liked.

I've been wanting to try a belt driven extruder. I just don't trust the accuracy of printed gears. Did you really notice much difference once you changed to it?

On my Y plate, I have tapped holes in the aluminum plate like you. I put a set of nuts below the plate, that have plastic knobs on them, that I can adjust by hand to lock them in place. Then an alan key from above. It may be a nicer solution that what you ended up with, and then you don't really need a wrench to hang onto the nuts. Better still might be some Nylok nuts with knobs.

Yes, Robotdigg shipping is quite high, but at least their prices are reasonable. They have the best pulleys I've found so far, and belt is really inexpensive. I'm driving my entire printer from 24V, so inductance is less of an issue for me. This might be one of the reason that those motors seem to perform so well. Alas, I am only running one of the motors on the X. My Y motor is inside the frame between the rods, and I don't have room for the longer ones, which is unfortunate, as it is the axis that could use more torque.

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Mike Anton
[manton.ca]
[laserlight.wikidot.com]

I tested the belt-pulley thing a bit, so am pretty confident -- the issue is mainly at higher speeds, and with a tight belt… if the motor's shaft isn't parallel there is enough force pushing the belt sideways (even if relatively slowly in comparison) that it will bind when it hits the side of the pulley (also possibly implicated -- with my pulleys, the sides are not parallel -- they are angled slightly inward). It still would hit though at "moderate" speeds, though more often several hours in.

During tests I would go immediately from having skipping within 3-4 layers @ 195mm/s non-printing moves to being able to complete hour-long prints (and removing my kludged-up stepper support would drop me right back where i was).

Right now the ringing is greatly reduced, though still noticeable -- I'm sure it would also be much better if i dropped down to 30mm/s speeds and/or dropped my jerk settings even further. Right now i'm also printing with an aluhotend without a fan (my current x carriage won't fit one with the small hotend; working on getting that sorted) rather than the E3D with fan and input / output ducts that I've mostly been using (which is being repaired) -- the lower mass also seems to be helping a bit; i'm going to see about increasing the rigidity of my hotend mounting as well -- I suspect the leverage due to the longer E3D barrel, especially with all the extra cooling weight, also contributes.

I'm also doing 24V -- seems like the way to go

Re: belt driven extruder -- it has been great -- though i'm also moving from ABS printed gears (was concerned about PLA gears in a heated chamber), and the ABS definitely wears over time. But with that caveat, I can actually see how much more uniform the plastic extrudes -- especially on the first layer, and finished parts seem quite a bit stronger (though I'm not ruling out possible psychosomatic influence on that part ). I picked up the gears from Terawatt Industries, though was concerned about some of the aspects of the 00str00der design (heavy motor hanging off to one side of flat X carriage)… so went with something based off of this design on Thingiverse: [www.thingiverse.com]

I had to stretch the stepper mount about 10% in order to get enough space to tighten the belt, and cut a cylinder out of the bottom of it so the top of my hotend would fit (also had to do some work with a chisel on a bearing inset to get the knurling on the bolt -- also picked up from Terawatt -- to line up with the filament path) … it's a little heavy, but for the most part has been great.

Also have to say that the Terawatt knurled extruder bolt has been working really quite well for me, though when ABS gets deeply impacted in the knurl i've sometimes ended up pulling it out and clean with a file brush when just poking with a pointy object doesn't seem to quite do it.

I have been able to do rapid moves at up to 300mm/s without skipping, and my belts usually rub at the ends of travel, though my pulley sides are parallel. I've noticed that with my belts tight, that they are not actually straight, and have a bend to them. It is very odd.

What are you using for acceleration? If you lower it, you will get less ringing without sacrificing peak speed. I think the default for marlin is 3000, and at that acceleration, I had lots of ringing, and the odd skipped step. Lowering it to 2100 pretty much eliminates the ringing, and I never lose steps. Lowering it further, seemed to make no difference.

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Mike Anton
[manton.ca]
[laserlight.wikidot.com]

I have used a ton of Igus bearings of all kinds over the years, and I just don't see them as useful in hobby 3D printers. Looking at their coefficient of friction tables you can see they range from about 0.06 to 0.20. Whats interesting too is that the coefficient is high at LOW loads! Now look at ball bushings. Coefficients of 0.001 to 0.01 typical. So for a 5 lb load the motor has to push with 0.3 to 1 lb of force to overcome the friction while a ball bushing is 0.005 lbs to 0.05 lbs! You are probably thinking your carriage doesn't weigh 5 lbs. The weight is not where most of the load comes from. It comes from the force between any two bearing points. So if you have ANY misalignment the motor force required goes way up. Then there is stick slip, when you reverse directions. The Igus bearings have stick slip, the ball bushings don't. Then read the RepRap forum with all these people with few mechanical skills and an even smaller understanding of what precision construction looks like. Read all the threads about burned up drivers, motors skipping, corners that aren't squared off, and on and on. Factor in that everyone wants cheap, really cheap, cheaper than Chinese cheap. This is not the place for plain bearings like Igus!

I received a sample kit from Igus, and I have to admit that the friction is much higher than I thought it would be. This is with non-adjustable carriages as well, and there is quite a bit of play in them. I would never use these ones for a 3D printer, as there is just too much play.

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Mike Anton
[manton.ca]
[laserlight.wikidot.com]

I was not impressed with Igus's stuff either in terms of the static friction threshold. PBC's variant however is proving to be quite an eye opener in terms of what plain bearings are capable of in terms of performance.

My next 3D printer will most likely be using their Mini-Rail as Y axis slides and the simplicity round shaft line for Z and X gantry. The only reason I'm using them on the Z is due to the Z rods transferring rotational motion up to the gantry, this combined rotational and linear requirement rules out traditional linear ball bearings.

Another perk of PBC's frelon liner material is the 400degF usage rating - something that will come in handy for hotter then ambient build environments.

Hello to all, since I see somebody here had experience with igus product I would like to ask (hoping not OT) if anybody had experience or know something about these DryLin T rails.
Here are the spces which seems to me very good, what are your thoughts about (manton, garyhlucas)?

I'm going to use them on my multifunctional printer. Thanks.

Edit: I'm asking because I'm going to buy these linear guides and they'll cost around 400€ in total, for me is a big purchase and I don't want to make mistakes.

Edited 1 time(s). Last edit at 05/09/2014 10:03AM by Gordie.

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---- "Let me make my move" ----