Best Belt-Less RepRap and Printer Designs (Rack & Pinion Rostock :S) Hi All, I would like to get your input. What are the best printer (or even independent axis) designs out which do not use belts? I am weary of stretching, sagging belt slop decreasing my print quality over time. I have been considering trying to custom build a rack & pinion Rostock or i3 Prusa; but before I go off trailblazing on some wild tangent, I thought I would see if anyone else is taking revenge on belts at the moment. Thanks for your thoughts https://reprap.org/forum/read.php?1,181517,181517#msg-181517 Sat, 14 Mar 2026 09:14:40 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?1,181517,185665#msg-185665 Re: Best Belt-Less RepRap and Printer Designs (Rack & Pinion Rostock :S) https://reprap.org/forum/read.php?1,181517,185665#msg-185665 -------------------------------------------------------
> Steel wire has to be the way to go. It doesn't
> stretch (normally) and is flexible enough to do a
> couple of turns around the drive motor.

Absolutely !
And I think wire-driven axis will be the standard system in repraps. It's easy to find (stainless steel fishing wire) and it doesn't need precision machined pulleys, simple printed cylinder will work just fine.
The important thing to remember is that it needs to be flexible. 7 strands wire doesn't work, I tried and it didn't pass the stress test, 49 strands wire works great.
You can see my system on the Heavy Mendel thread : [forums.reprap.org]

Things I printed with it for the print something really tiny competition :
[forums.reprap.org]
[youtu.be]]]> Petrus General Mon, 18 Feb 2013 12:04:38 -0500 https://reprap.org/forum/read.php?1,181517,185505#msg-185505 Re: Best Belt-Less RepRap and Printer Designs (Rack & Pinion Rostock :S) https://reprap.org/forum/read.php?1,181517,185505#msg-185505 crispy1 General Sun, 17 Feb 2013 19:30:18 -0500 https://reprap.org/forum/read.php?1,181517,185502#msg-185502 Re: Best Belt-Less RepRap and Printer Designs (Rack & Pinion Rostock :S) https://reprap.org/forum/read.php?1,181517,185502#msg-185502 -------------------------------------------------------
> n some sense you are correct in that the fibres in
> the belt should not stretch ( but still do and
> that is why you can buy really expensive belts
> with Kevlar or steel in them).
>
> I think all timing belts have Kevlar or steel in
> them and they are not massively expensive. Rubber
> belts without reinforcement are not timing belts
> and would be useless in this application.
>
> That said they are not infinitely stiff,
> especially when they hang in a catenary. I wonder
> if turning them 90 degrees like the original
> Mendel X axis is significantly better as they
> would sag less. When used to drive a lead screw
> they are vertical, so would not sag with gravity.

All general purpose timing belts I have seen start with fibreglass reinforcements and then Nylon and the Kevlar or steel, the latter two being the best and most expensive.]]> Sublime General Sun, 17 Feb 2013 19:10:13 -0500 https://reprap.org/forum/read.php?1,181517,185500#msg-185500 Re: Best Belt-Less RepRap and Printer Designs (Rack & Pinion Rostock :S) https://reprap.org/forum/read.php?1,181517,185500#msg-185500
Quote

n some sense you are correct in that the fibres in the belt should not stretch ( but still do and that is why you can buy really expensive belts with Kevlar or steel in them).

I think all timing belts have Kevlar or steel in them and they are not massively expensive. Rubber belts without reinforcement are not timing belts and would be useless in this application.

That said they are not infinitely stiff, especially when they hang in a catenary. I wonder if turning them 90 degrees like the original Mendel X axis is significantly better as they would sag less. When used to drive a lead screw they are vertical, so would not sag with gravity.]]> nophead General Sun, 17 Feb 2013 19:05:32 -0500 https://reprap.org/forum/read.php?1,181517,185467#msg-185467 Re: Best Belt-Less RepRap and Printer Designs (Rack & Pinion Rostock :S) https://reprap.org/forum/read.php?1,181517,185467#msg-185467 -------------------------------------------------------
> Seriously guys, spend five seconds researching
> your claims before making them.

In some sense you are correct in that the fibres in the belt should not stretch ( but still do and that is why you can buy really expensive belts with Kevlar or steel in them). But the rubber on the outside can deflect a little as the pulley changes direction. On a CNC milling machine with belts driving a rack or lead screw this is not an issue because they change direction very slowly. But on a 3D printer it changes direction really fast. For the best prints we want really high acceleration and belts start to show backlash at that point. The above example from Trinity labs is changing direction and accelerating at over 1g (goes from 0 to 300mm/s at 10,000mm/s^2).]]> Sublime General Sun, 17 Feb 2013 16:51:49 -0500 https://reprap.org/forum/read.php?1,181517,185440#msg-185440 Re: Best Belt-Less RepRap and Printer Designs (Rack & Pinion Rostock :S) https://reprap.org/forum/read.php?1,181517,185440#msg-185440

Modern belts have essentially zero stretch. Your belts are not stretching, your machine has just gotten loose and all the parts are jiggling around.

Belts are used literally everywhere in ultra high precision machines. Cnc mills costing more than most houses use belts to drive their ballscrews. Such mills maintain accuracy in the micron range over decades. Gantry mills and routers use belts directly for linear motion and regularly move hundreds of pounds with 0.001" accuracy.


Leadscrews are acceptable but in most cases not beneficial for 3d printers. Belts are already accurate and rigid enough for a 3d printer, so a screw provides no advantages but increases the inertia of your load and limits top speeds.

PS. DumpsterCNC came up with your "constant force nuts" first: [www.dumpstercnc.com].


Regardless of how many dollars you spend on screws, belts, or other form of linear motion, the results will always be the same. If you can twist your printer into a pretzel by hand, the frame is going to move far, far, more than the belts or screws ever will.


If you are genuinely interested in making your machine perform better, people have been building machines for centuries that can hold tolerances three or four orders of magnitude tighter than printers. You don't need to reinvent the wheel.]]> 691175002 General Sun, 17 Feb 2013 16:03:17 -0500 https://reprap.org/forum/read.php?1,181517,185393#msg-185393 Re: Best Belt-Less RepRap and Printer Designs (Rack & Pinion Rostock :S) https://reprap.org/forum/read.php?1,181517,185393#msg-185393 Maybe I will implement one of these leadscrews in my printer, too, but I have purchased my drive system already.

I am not too sure about your statement regarding wearing out the GT2 parts, though. In vehicles and industrial equipment, timing belts have to endure much more stress than on our printers, still, they hold up quite well because they are adequately specified and correctly implemented unlike in some of our printers. I chose the original Gates GT3 belt that is rated for higher tor higher torque than the previous GT2 generation precisely because I wanted a long-lasting system (I just don't know where the GT2 belts in various web shops come from; GT3 is downwards compatible). In addition to that, the idlers over which the back side of the belt runs are larger than the pulleys, just according to specs.
So, in theory, it should last me a long time since I constructed the belt path according to Gates' specifications, but I have yet to prove this assumption.]]> uGen General Sun, 17 Feb 2013 13:32:57 -0500 https://reprap.org/forum/read.php?1,181517,185149#msg-185149 Re: Best Belt-Less RepRap and Printer Designs (Rack & Pinion Rostock :S) https://reprap.org/forum/read.php?1,181517,185149#msg-185149 vulcanrd General Sat, 16 Feb 2013 11:35:49 -0500 https://reprap.org/forum/read.php?1,181517,185148#msg-185148 Re: Best Belt-Less RepRap and Printer Designs (Rack & Pinion Rostock :S) https://reprap.org/forum/read.php?1,181517,185148#msg-185148 Pics on site do not show it.
I see repeative structures on vertical walls
and wavy traces after head direction changes.]]> karabas General Sat, 16 Feb 2013 11:25:44 -0500 https://reprap.org/forum/read.php?1,181517,185088#msg-185088 Re: Best Belt-Less RepRap and Printer Designs (Rack & Pinion Rostock :S) https://reprap.org/forum/read.php?1,181517,185088#msg-185088
We don't actually know the limits oif lifetime on these leadscrews with the constant force nuts and the SIMO stages I codeveloped with PBC. I recently visited their headquarters in chicago a week or two ago and got to see the whole room deveoted to the SIMO stages for TrinityLabs and the Aluminatus.

And they still have the very first production SIMO stage like on the Alu8minatus XY axis in a test harness and it has been running back and forth with a 4 kilo brick on the carriage at 300mm/sec since August 21st 24/7 non stop and still is not showing *any* signs of wear on the slider or the leadscrew,

The constant force antilash nuts are truly something special. rather then the traditional preloaded antilash nuts that push apart the twoi ends of the leadscrew nut with springs and compensate for wear by letting the plastic wear away more and more until it doesn't really compensAte for lash anymore the constant force nuts have round metal bands kind of rolled up like the element in a ciggarette lighter in a car wrapped around 3 places on the leadscrew nut where there are 3 or 4 "fingers" that have threads on the inside. So instead of getting contact with the screw and the threads only on one small ti[p pof the leadscrew nut the constant force nuts get cponstant force contact for like 20mm of thread and therefor do not wear nearly as fast.

I am not personally familiar with the supposed lomnger lasting screws anbd nuts linked above in this thread but the first production SIMO stage configured identically to the ones I am shipping on the Aluminatus has been running back and foreth across 320mm of travel at 300mm/sec speed and 10,000 acceleration setting since August 21st which is over 5 months of 24/7 300mm/sec back and forth travel without showing any signs of wear yet. If that won't last longer then most of the rest of yoru printer I do not know what will.

So while I cannot give you s[pecs or stats from the manufacturer, I can give you hard seen with my own eyes info about one of these sytages running almost at full speed back and forth with 4 kilo brick on the car for close to 6 months now without signs of giving up. This is a lot more then "a few prints" that folks are saying igus screws would be capable of doing. I think those igus screws would last a lot longer then a few prints honestly but i know for fact that I have no worries about the PBC linear constant force nuts and multistart leadscrews wearing out prematurely.

In fact I warantee the X and Y stages for a full year after purchase with free replacement no questions asked if they fail in the first year. Of coursze I'm not gonna cover your stepper motor because people can do dumb things and ruin those easily but the linear stage anbd leadscrew + nut is going to last you a full year of as much printing as you can do or I will replace it.

I have nbo doubts that Aluminatus printers will still be printing 5 yearsa from now based on the ones going out the door today.

In fact I bet you would wear out your GT2 belts and pulleys ,multiple times befotre you come close to wearing out these screws.

-Ezra]]> Ezra Zygmuntowicz General Sat, 16 Feb 2013 04:28:19 -0500 https://reprap.org/forum/read.php?1,181517,184766#msg-184766 Re: Best Belt-Less RepRap and Printer Designs (Rack & Pinion Rostock :S) https://reprap.org/forum/read.php?1,181517,184766#msg-184766 On paper, these leadscrews really look impressive and I am sure that they will also perform well. However, when I looked into this whole matter of alternative drive mechanisms, it became quite clear that wear life of these fast leadscrews would one of the more limiting factors (along with complexity of implementation due to the bearing blocks). Speed absolutely is not the problem; in fact, my configuration with a 20 tooth GT2 pulley and a pulley system similar to the Printxel would be slower than your leadscrews.
So, do you know the service life of the leadscrews? PBC really does not seem to like publishing this data as openly as others although their products seem to stack up quite well against the competition.]]> uGen General Thu, 14 Feb 2013 18:50:42 -0500 https://reprap.org/forum/read.php?1,181517,184705#msg-184705 Re: Best Belt-Less RepRap and Printer Designs (Rack & Pinion Rostock :S) https://reprap.org/forum/read.php?1,181517,184705#msg-184705
These graphs were done in the lab at PBC while we were codeveloping the specific screws we use in our Aluminatus printers and the ones we sell in our store. This is made form true recorded data I witnessed firsthand >>

[brainspl.at]

Here is the vendor's information PDF about the technology in these leadscrews and constant force antibacklash nuts

[www.pbclinear.com]

You can get leadscrews and nuts direct from PBC or one of their distributors but you will pay more and the customized version I have had made specifically for the motion profile of 3d printing are not a stock available item from them.

Not trying to sell anyone here by any means and won't link to my shop but wantd to provide you with the spec sheets you were looking for and information on alternate sources then myself.

FWIW we use triple stack nema17's at 112oz-in with 10 start 25mm pitch PTFE coated screws and can attain a top speed of 390mm/sec with 40,000 acceleration setting for the XY axis in marlin firmware. But be ware that screws this fast do max out the 8 bot corens in arduino based electronics and work even way better on smoothieboard or 4pi or a 32bit arm based motion control platform.

Cheers-
-Ezra]]> Ezra Zygmuntowicz General Thu, 14 Feb 2013 15:26:47 -0500 https://reprap.org/forum/read.php?1,181517,183161#msg-183161 Re: Best Belt-Less RepRap and Printer Designs (Rack & Pinion Rostock :S) https://reprap.org/forum/read.php?1,181517,183161#msg-183161 uGen General Fri, 08 Feb 2013 16:22:57 -0500 https://reprap.org/forum/read.php?1,181517,183051#msg-183051 Re: Best Belt-Less RepRap and Printer Designs (Rack & Pinion Rostock :S) https://reprap.org/forum/read.php?1,181517,183051#msg-183051
Not sureI am ready to drop $100 on them.

I did however pick up one of their little stepper motors with attached delrin gearboxes though.]]> Idolcrasher General Fri, 08 Feb 2013 10:04:37 -0500 https://reprap.org/forum/read.php?1,181517,183050#msg-183050 Re: Best Belt-Less RepRap and Printer Designs (Rack & Pinion Rostock :S) https://reprap.org/forum/read.php?1,181517,183050#msg-183050
Fair enough, I can respect those reasons.]]> crispy1 General Fri, 08 Feb 2013 10:00:20 -0500 https://reprap.org/forum/read.php?1,181517,183022#msg-183022 Re: Best Belt-Less RepRap and Printer Designs (Rack & Pinion Rostock :S) https://reprap.org/forum/read.php?1,181517,183022#msg-183022 As both Igus and Reliance Precision Mechatronics provide a wealth of information on their sites, it was only natural to quote their data.]]> uGen General Fri, 08 Feb 2013 07:13:37 -0500 https://reprap.org/forum/read.php?1,181517,182952#msg-182952 Re: Best Belt-Less RepRap and Printer Designs (Rack & Pinion Rostock :S) https://reprap.org/forum/read.php?1,181517,182952#msg-182952 Must use these on the next printer, wonder if they are as good as they claim.]]> Wired1 General Thu, 07 Feb 2013 22:17:22 -0500 https://reprap.org/forum/read.php?1,181517,182944#msg-182944 Re: Best Belt-Less RepRap and Printer Designs (Rack & Pinion Rostock :S) https://reprap.org/forum/read.php?1,181517,182944#msg-182944
Have you guys been living under a rock? :-P

[trinitylabs.com]
[trinitylabs.com]
[trinitylabs.com]
and
[trinitylabs.com]]]> crispy1 General Thu, 07 Feb 2013 21:58:47 -0500 https://reprap.org/forum/read.php?1,181517,182939#msg-182939 Re: Best Belt-Less RepRap and Printer Designs (Rack & Pinion Rostock :S) https://reprap.org/forum/read.php?1,181517,182939#msg-182939 Idolcrasher General Thu, 07 Feb 2013 21:25:54 -0500 https://reprap.org/forum/read.php?1,181517,182496#msg-182496 Re: Best Belt-Less RepRap and Printer Designs (Rack & Pinion Rostock :S) https://reprap.org/forum/read.php?1,181517,182496#msg-182496 The good news: There is another manufacturer located in the UK: Reliance Precision Mechatronics. I don't exactly know what they do differently, but some of their leadscrews are rated for up to 7000km service life, which would last some years even if one were to print one medium sized to large object per day.

What I would do about belt stretch is to take broader belts or to build a pulley system that also doubles your theoretical resolution while putting less strain on your belt.]]> uGen General Wed, 06 Feb 2013 09:54:29 -0500 https://reprap.org/forum/read.php?1,181517,182411#msg-182411 Re: Best Belt-Less RepRap and Printer Designs (Rack & Pinion Rostock :S) https://reprap.org/forum/read.php?1,181517,182411#msg-182411 [reprap.org]

Anyway, Synchromesh is interesting enough for me to give it a try.]]> Pazu General Wed, 06 Feb 2013 02:58:06 -0500 https://reprap.org/forum/read.php?1,181517,182369#msg-182369 Re: Best Belt-Less RepRap and Printer Designs (Rack & Pinion Rostock :S) https://reprap.org/forum/read.php?1,181517,182369#msg-182369
Quote

Also, how on earth do u design anti-backlashing into a belt? I don't see how mechanically superior can a GT2 belt be. At least in terms of handling backlashing.

Disclaimer: I'm not a belt engineer, this is my understanding which could certainly be flawed.

It has to do with the tooth profile, and how the teeth on the belt engage with the pulley. This is why GT2, with its semicircular teeth, is superior to T5, with its larger and trapezoidal teeth.

Keep in mind there is a difference between what T5 was designed for - light duty power transmission, where positional accuracy is not extremely important, and what we need for our printers. For us, positional accuracy is paramount, so any slop in the teeth paying on or off the pulley when the motor reverses direction is not desirable.

My interpretation is that synchromesh is designed more as a replacement for T5 than for GT2.

And before anyone objects - yes, you can get good results from T5 belts. But you end up applying so much tension it basically acts like a piece of cable - the teeth are no longer what keeps the belt from slipping, friction is.]]> crispy1 General Tue, 05 Feb 2013 22:14:18 -0500 https://reprap.org/forum/read.php?1,181517,182360#msg-182360 Re: Best Belt-Less RepRap and Printer Designs (Rack & Pinion Rostock :S) https://reprap.org/forum/read.php?1,181517,182360#msg-182360 -------------------------------------------------------
> How about Synchromesh?
>
>
> I kinda want to try them out in my next printer
> project.
>
> According to an applications engineer at SDP-SI,
> synchromesh is not a good choice for our
> application because it is not anit-backlash like
> GT2 belts are.
>
> If you want more details you'll need to poke into
> the IRC and ask around - I wasn't the person who
> asked SDP-SI, and my memory on who did is a bit
> fuzzy.

I think I might have heard that before. And I think I've heard of counter-arguements that they are a good fit for our application. Seeing the website, it seems to be specifically designed for small belt driven machines.
[sdp-si.com]

Also, how on earth do u design anti-backlashing into a belt? I don't see how mechanically superior can a GT2 belt be. At least in terms of handling backlashing.]]> Pazu General Tue, 05 Feb 2013 21:09:55 -0500 https://reprap.org/forum/read.php?1,181517,182216#msg-182216 Re: Best Belt-Less RepRap and Printer Designs (Rack & Pinion Rostock :S) https://reprap.org/forum/read.php?1,181517,182216#msg-182216 -------------------------------------------------------
> Synchro mesh looks pretty cool :)
>
> I use GT2 Belts and they stretched on me over 3-4
> months.
>
> Are they done stretching? Maybe?
>
> Would I prefer a product that does not stretch at
> all? Certainly.

How much did it stretch? I haven't witnessed any myself in over a year and I have used steel wire belts as well as more flexible (and more common) PU fibers. Perhaps you have them significantly over tensioned.]]> yydoctt General Tue, 05 Feb 2013 11:50:30 -0500 https://reprap.org/forum/read.php?1,181517,182212#msg-182212 Re: Best Belt-Less RepRap and Printer Designs (Rack & Pinion Rostock :S) https://reprap.org/forum/read.php?1,181517,182212#msg-182212
I use GT2 Belts and they stretched on me over 3-4 months.

Are they done stretching? Maybe?

Would I prefer a product that does not stretch at all? Certainly.]]> Idolcrasher General Tue, 05 Feb 2013 11:34:51 -0500 https://reprap.org/forum/read.php?1,181517,182187#msg-182187 Re: Best Belt-Less RepRap and Printer Designs (Rack & Pinion Rostock :S) https://reprap.org/forum/read.php?1,181517,182187#msg-182187
Quote

How about Synchromesh?
[www.thingiverse.com]

I kinda want to try them out in my next printer project.

According to an applications engineer at SDP-SI, synchromesh is not a good choice for our application because it is not anit-backlash like GT2 belts are.

If you want more details you'll need to poke into the IRC and ask around - I wasn't the person who asked SDP-SI, and my memory on who did is a bit fuzzy.]]> crispy1 General Tue, 05 Feb 2013 08:38:09 -0500 https://reprap.org/forum/read.php?1,181517,182129#msg-182129 Re: Best Belt-Less RepRap and Printer Designs (Rack & Pinion Rostock :S) https://reprap.org/forum/read.php?1,181517,182129#msg-182129 [www.thingiverse.com]

I kinda want to try them out in my next printer project.]]> Pazu General Tue, 05 Feb 2013 04:20:01 -0500 https://reprap.org/forum/read.php?1,181517,182077#msg-182077 Re: Best Belt-Less RepRap and Printer Designs (Rack & Pinion Rostock :S) https://reprap.org/forum/read.php?1,181517,182077#msg-182077
Quote

I'm really surprised that a hardened steel and metal bushing setup is not more popular here... It has almost as little friction as bearings and less slop than LM8UUs and regular smooth rod... And is lighter as well...

I did find the bushings to be smoother than the linear bearings. However, they are less tolerant of off-axis loads in that they are more inclined to jam or stick and enter "stick-slip" motion.

My main problem with belts is that they are rather expensive and difficult to source. And you either need to have toothed idlers or run the smooth side of the belt over the idler in order to eliminate the tooth artifacts from prints.]]> crispy1 General Mon, 04 Feb 2013 20:43:44 -0500 https://reprap.org/forum/read.php?1,181517,181932#msg-181932 Re: Best Belt-Less RepRap and Printer Designs (Rack & Pinion Rostock :S) https://reprap.org/forum/read.php?1,181517,181932#msg-181932 They have CAD models online and discounts for quantity orders.
They've also got an aluminum rod, precision ground, really straight and light. AWM shafts work with J.]]> davew_tx General Mon, 04 Feb 2013 10:03:06 -0500 https://reprap.org/forum/read.php?1,181517,181799#msg-181799 Re: Best Belt-Less RepRap and Printer Designs (Rack & Pinion Rostock :S) https://reprap.org/forum/read.php?1,181517,181799#msg-181799
As far as the drive for axis, I really think belts are the way to go. I'm not sure what people have against them, they can be very accurate when used properly.]]> xclusive585 General Sun, 03 Feb 2013 21:17:05 -0500