Replace timing belts with FireLine Hi, I am very curious with the approach to replace traditional timing belts with FireLine (FireLine have no stretch), there is video on this approach but extremely little actual information about the subject. FireLine has no stretch what so ever, and high tensile strength, the 0,32mm cord I have has a 24kg breaking strength, which I believe is more than enough for the purpose in 3D printing. By looking at the video from the source information, he uses quite large pulley "gear" wheels attached to the motor (which also btw looks like Nema 23 that provides more torque, maybe 0,9deg/step?) considering I am working with 1,8deg/step Nema 17 motors the size in the video would be very inefficient. [url=https://www.youtube.com/watch?v=JFOXgfbH_gM]Source video.[/url] So I got into some math figuring out a optimal size for the pulley as its not actually a "gear", my Nema 17 with 1,8 deg step angle being ran with 1/16 micro stepping one full revolution is 3200 steps (360/1,8=200*16=3200) Now lets say we want to have movement being able to divide into whole numbers at a resolution of 0,01mm. 3200*0,01 = 32 (circumference of pulley) 32/3,14 = 10,19 (diameter of pulley) 1/0,01 = 100 (steps per mm) Perfect this diameter also provide decent torque compared to traditional GT2 pulley wheels having 80steps per mm (resulting in 12,73mm diameter or 40mm circumference gear) increasing potentional torque by 25%! (10,19*[u]1,25[/u]=[b]12,73[/b]) Initially I designed a stepper wheel, without any fastening on the pulley for the cord I believed that twinning the cord around the pulley 3-4 times would provide enough friction without slippage, however after some attempts I quickly realize that this is not the case due to the material of the pulley and the coating on the FireLine itself. [attachment 103685 StepperWheel-Firelinev1.png] I would love to hear suggestions on this! Thanks for reading. https://reprap.org/forum/read.php?14,815780,815780#msg-815780 Fri, 14 Aug 2026 15:10:25 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?14,815780,835635#msg-835635 Re: Replace timing belts with FireLine https://reprap.org/forum/read.php?14,815780,835635#msg-835635
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Poorly made machine have their belt not tensioned enough ! Acrylic frame, extrusion not beefy enough, flimsy 3D printed parts etc...

Agreed.
That's why I prefer guiding the belt ( or cable ) through the slots: there are no sideloads on the extrusion...no matter how tight.]]> o_lampe Mechanics Sat, 06 Oct 2018 02:23:23 -0400 https://reprap.org/forum/read.php?14,815780,835570#msg-835570 Re: Replace timing belts with FireLine https://reprap.org/forum/read.php?14,815780,835570#msg-835570
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gmedlicott
...Reasoning being our 3d printers have belts that have very little tension to the point of having slack, so when one belt applies force in the opposite direction of travel the belt stretches until traveling in the force direction, then resonates by relaxing and stretching until the energy is dissipated. I think the relaxing portion doesn't stretch the other slack belt to the point of it's spring being meaningful. I could be wrong, just got me thinking.

Moral of the exercise though: use highest belt tension (to use more of the second belt spring), along with lowest moving mass, shortest belt, and slowest accelerations.

Poorly made machine have their belt not tensioned enough ! Acrylic frame, extrusion not beefy enough, flimsy 3D printed parts etc... My 6mm GT2 are tensioned to 26N, no slack at all.
Note a flexible built is what allowed most to function without binding :)

One has also to account for the dampening effect of bushings when made with Igus or similar material.]]> MKSA Mechanics Fri, 05 Oct 2018 06:10:03 -0400 https://reprap.org/forum/read.php?14,815780,835528#msg-835528 Re: Replace timing belts with FireLine https://reprap.org/forum/read.php?14,815780,835528#msg-835528
For the belt section, while textbook correct for a two spring + mass arrangement, I think in practice you can only use the belt doing the pulling to determine resonance frequency. Reasoning being our 3d printers have belts that have very little tension to the point of having slack, so when one belt applies force in the opposite direction of travel the belt stretches until traveling in the force direction, then resonates by relaxing and stretching until the energy is dissipated. I think the relaxing portion doesn't stretch the other slack belt to the point of it's spring being meaningful. I could be wrong, just got me thinking.

Moral of the exercise though: use highest belt tension (to use more of the second belt spring), along with lowest moving mass, shortest belt, and slowest accelerations.]]> gmedlicott Mechanics Thu, 04 Oct 2018 16:35:58 -0400 https://reprap.org/forum/read.php?14,815780,835514#msg-835514 Re: Replace timing belts with FireLine https://reprap.org/forum/read.php?14,815780,835514#msg-835514
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the_digital_dentist
Motor to carriage belt length varies depending on carriage position. What numbers are you looking for there?

The predominant resonant frequencies will change with belt length too. You could use the spreadsheet to get some idea of the likely spread.]]> dc42 Mechanics Thu, 04 Oct 2018 12:26:05 -0400 https://reprap.org/forum/read.php?14,815780,835490#msg-835490 Re: Replace timing belts with FireLine https://reprap.org/forum/read.php?14,815780,835490#msg-835490 the_digital_dentist Mechanics Thu, 04 Oct 2018 07:20:53 -0400 https://reprap.org/forum/read.php?14,815780,835475#msg-835475 Re: Replace timing belts with FireLine https://reprap.org/forum/read.php?14,815780,835475#msg-835475
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the_digital_dentist
The magnetic fields acting against the rotor in the motor act like a spring with a mass (the rotor) hanging from it. The mass of the extruder carriage and/or Y axis or bed assembly adds to the moving masses that have to be accelerated. The whole system is a spring (the motor) coupled to a moving mass (the printer mechanism) by another spring (the belt). You can't eliminate ringing just by playing with the belt. It is a much more complex problem than that.

I put together a spreadsheet to estimate the effects of belt elasticity and motor elasticity on Cartesian printers. It's at [www.dropbox.com]. For CoreXY printers there are probably some factors of 2 or sqrt(2) to be included somewhere.]]> dc42 Mechanics Thu, 04 Oct 2018 04:09:36 -0400 https://reprap.org/forum/read.php?14,815780,835467#msg-835467 Re: Replace timing belts with FireLine https://reprap.org/forum/read.php?14,815780,835467#msg-835467
As for GT2 stretch versus round cable, seriously, the GT2 is basically just a FLAT cable(which is better than round of same section area) made with similar low stretch fiber plus some tooth. True you will get a cheaper round cable than a belt with the same "stretch" BUT to fulfill the other requirements the belt achieves, good luck to do it for the same cost and ease.
If it can be done, even "good enough" ! Cables have been used in early robot arms decades ago.]]> MKSA Mechanics Thu, 04 Oct 2018 02:31:29 -0400 https://reprap.org/forum/read.php?14,815780,835450#msg-835450 Re: Replace timing belts with FireLine https://reprap.org/forum/read.php?14,815780,835450#msg-835450 the_digital_dentist Mechanics Wed, 03 Oct 2018 17:21:42 -0400 https://reprap.org/forum/read.php?14,815780,835430#msg-835430 Re: Replace timing belts with FireLine https://reprap.org/forum/read.php?14,815780,835430#msg-835430
edit: well thats an awesome link... down the rabbit hole i going it seems. never gonna run out of things to test in calibration.]]> warbunniex Mechanics Wed, 03 Oct 2018 14:38:35 -0400 https://reprap.org/forum/read.php?14,815780,835417#msg-835417 Re: Replace timing belts with FireLine https://reprap.org/forum/read.php?14,815780,835417#msg-835417
See this: [forum.duet3d.com]]]> the_digital_dentist Mechanics Wed, 03 Oct 2018 12:22:28 -0400 https://reprap.org/forum/read.php?14,815780,835408#msg-835408 Re: Replace timing belts with FireLine https://reprap.org/forum/read.php?14,815780,835408#msg-835408
Ask far as testing goes: I tiried putting the wire on top of the belt of the tevo & it didnt want to stay there so i put it next to the belt. It looks like it reduced belt stretching. I'm going to do a proper photo comparison & try a slightly different placement on the printer. The good news is, if it is an improvement for the tevo, its a damn quick & easy upgrade. only had to tap 2 holes in the carriage for the bed for some screws.]]> warbunniex Mechanics Wed, 03 Oct 2018 10:18:31 -0400 https://reprap.org/forum/read.php?14,815780,835366#msg-835366 Re: Replace timing belts with FireLine https://reprap.org/forum/read.php?14,815780,835366#msg-835366 Now I think of a combination of the Cloverleaf drive and a fixed cable. That could eliminate walking and slip once and for all time.

@TDD
I agree with the cable stretch. I had to retension it very often in the beginning, because I didn't 'prestretch' it before use.
Once it has stretched out, the braides are so tight that it feels really stiff. From then on, there is no more stretch.

About ringing in the motors: Does a 1.8° stepper ring twice as much as a 0.9° stepper?]]> o_lampe Mechanics Wed, 03 Oct 2018 02:12:06 -0400 https://reprap.org/forum/read.php?14,815780,835353#msg-835353 Re: Replace timing belts with FireLine https://reprap.org/forum/read.php?14,815780,835353#msg-835353
Anyways, back to finding a solution to a cable drive. There are two main "issues", slipping and string walking. I'm not sure how much of an issue slipping really is with proper tension. The printer re-homes before each print so any slip is "reset" at that point, and I don't see artifacts like slanted walls or mini missed step like artifacts in cable driven printers that would suggest the cable is slipping noticeably. The answer to this is fairly simple, just anchor the line to the pulley or use an appropriate number of wraps or tension to avoid slipping.

The second issue is string walking, and this is especially an issue with longer spans. Not necessarily because the error would increase substantially (as long as you keep the limits of travel at a reasonable distance to the drive pulley), but because it requires a longer and longer drive pulley. Usually the idler and driven end of the line "walk" in opposite directions which makes a changing angle which introduces some (possibly negligible, depending on machine size) error. In terms of getting rid of that error, you could "cross" the incoming and outgoing lines so they both walk in the same direction and the angle stays constant. You still need some length of drive pulley to accommodate this "walking" but it won't come with any triangulation error. For larger spans that would require ridiculously sized drive pulleys, you're better off going with polygonhell's stepped idler like solution that guides the cable along a consistent path but allows for a large cable to pulley contact.

Those solutions are good enough for me and cover both small and large scale CNC machines. For small scale machines it may not be worth it since the cost of short belts isn't too big, but if you're building a large format machine ala hangprinter, maslow CNC or a large MPCNC like setup, the belts become fairly expensive. It's not the "best" solution performance wise but it may work "good enough" and is much cheaper (don't compare a short belt to a spool of cable, compare them length for length which is how you'll use them).]]> Trakyan Mechanics Tue, 02 Oct 2018 21:07:50 -0400 https://reprap.org/forum/read.php?14,815780,835336#msg-835336 Re: Replace timing belts with FireLine https://reprap.org/forum/read.php?14,815780,835336#msg-835336
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Trakyan
Belt stretch can be a problem, especially under dynamic load. It gives us ringing.

For a given cross section, PE fishing line has a less stretch than kevlar or glass fibres. It has a higher young's modulus than those two. It also outperforms steel cables but I can't remember if it was by weight or cross sectional area. Regardless of how it outperforms steel in terms of strength it has a much lower minimum bend radius which is useful.

Last time I looked at a belt under a microscope,



there were about 19 glass cables, about 0.2mm in diameter running down its length. That would have a total cross sectional area of about 0.6 mm^2 (equivalent to 0.87 mm dia). Unless your cable is bigger than that, it is going to stretch more than a belt. I recently built a large corexy mechanism for a sand table using 0.5 mm diameter dyneema fishing line and it stretched a lot (maybe 10x) more than a belt. I have a direct comparison because I gave up on the cable and switched to belts in the same mechanism. Plastic cables creep which means the tension will drop after a while under tension, and you'll have to retension it. Creep can't go on forever and eventually the cable will fail as you retension it.

Belt stretch isn't the main cause of ringing. The motor acts more like a spring than a belt ever will.
]]> the_digital_dentist Mechanics Tue, 02 Oct 2018 16:15:20 -0400 https://reprap.org/forum/read.php?14,815780,835298#msg-835298 Re: Replace timing belts with FireLine https://reprap.org/forum/read.php?14,815780,835298#msg-835298
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warbunniex
digital dentist - belt stretching has been a huge problem. specially for any prusa style machine with a 300mmx300mm bed. but also for machines like deltas with really long lengths of belt.

it actually bothers me that chinese companies still use 6mm belt for the y axis of prusa style machines cause it would be the biggest improvement to performance if they went with a 15 or 20mm belt & would honestly not cost much more.

mksa & o lamp - interesting I will have to record what it does to the belt over time! if the belt lasts even a year, id consider it worth it.

The problem is the wrong choice of belt, material, width, length .... Chinese does it for a cost reason, even if the gain is minimal. They simply don't care about technicalities as long as people buy. And people keep buying because they don't know better. A bigger 3D printer ? Simple just longer extrusions, longer guides, longer belts. What about section, weight etc ... ? Ah it is important ? See here, plenty of example.]]> MKSA Mechanics Tue, 02 Oct 2018 11:40:12 -0400 https://reprap.org/forum/read.php?14,815780,835281#msg-835281 Re: Replace timing belts with FireLine https://reprap.org/forum/read.php?14,815780,835281#msg-835281
it actually bothers me that chinese companies still use 6mm belt for the y axis of prusa style machines cause it would be the biggest improvement to performance if they went with a 15 or 20mm belt & would honestly not cost much more.

mksa & o lamp - interesting I will have to record what it does to the belt over time! if the belt lasts even a year, id consider it worth it.]]> warbunniex Mechanics Tue, 02 Oct 2018 09:50:54 -0400 https://reprap.org/forum/read.php?14,815780,835239#msg-835239 Re: Replace timing belts with FireLine https://reprap.org/forum/read.php?14,815780,835239#msg-835239
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o_lampe
...
I think, adding an extra layer around the belt would cut into the belt and destroy it eventually. It needs a higher tension then belt alone.
Obviously ! The location of the core fiber strands are precisely located in the "neutral plane". where there is no stretch when the belt goes around a pulley.
To add a layer outside and the belt will wrinkle badly.]]> MKSA Mechanics Tue, 02 Oct 2018 03:37:26 -0400 https://reprap.org/forum/read.php?14,815780,835230#msg-835230 Re: Replace timing belts with FireLine https://reprap.org/forum/read.php?14,815780,835230#msg-835230
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warbunniex
Just a thought.

So I decided to get some 100 pound fishing line for 10 dollars on amazon & used it as a hybrid system on my delta. It cut the belt length in slightly more than half and as allowed me to increase the acceleration & keep quality. And that got my thinking about hybrid systems.

Could be not keep the belt & run a fishing line over top of it? I'm gonna test it on the y axis of our local maker space's tevo tornado but I think it would at least help a little bit with the belt stretch.

It's definitely something worth thinking about! Why aren't there Kevlar or highclass PE reinforced belts?
I think, adding an extra layer around the belt would cut into the belt and destroy it eventually. It needs a higher tension then belt alone.]]> o_lampe Mechanics Tue, 02 Oct 2018 01:33:10 -0400 https://reprap.org/forum/read.php?14,815780,835224#msg-835224 Re: Replace timing belts with FireLine https://reprap.org/forum/read.php?14,815780,835224#msg-835224
For a given cross section, PE fishing line has a less stretch than kevlar or glass fibres. It has a higher young's modulus than those two. It also outperforms steel cables but I can't remember if it was by weight or cross sectional area. Regardless of how it outperforms steel in terms of strength it has a much lower minimum bend radius which is useful.]]> Trakyan Mechanics Mon, 01 Oct 2018 20:34:29 -0400 https://reprap.org/forum/read.php?14,815780,835160#msg-835160 Re: Replace timing belts with FireLine https://reprap.org/forum/read.php?14,815780,835160#msg-835160 Does fishing line stretch less?]]> the_digital_dentist Mechanics Mon, 01 Oct 2018 11:21:23 -0400 https://reprap.org/forum/read.php?14,815780,835156#msg-835156 Re: Replace timing belts with FireLine https://reprap.org/forum/read.php?14,815780,835156#msg-835156
So I decided to get some 100 pound fishing line for 10 dollars on amazon & used it as a hybrid system on my delta. It cut the belt length in slightly more than half and as allowed me to increase the acceleration & keep quality. And that got my thinking about hybrid systems.

Could be not keep the belt & run a fishing line over top of it? I'm gonna test it on the y axis of our local maker space's tevo tornado but I think it would at least help a little bit with the belt stretch.]]> warbunniex Mechanics Mon, 01 Oct 2018 10:57:05 -0400 https://reprap.org/forum/read.php?14,815780,833713#msg-833713 Re: Replace timing belts with FireLine https://reprap.org/forum/read.php?14,815780,833713#msg-833713 accidently overlapping cables.]]> o_lampe Mechanics Sat, 15 Sep 2018 03:47:27 -0400 https://reprap.org/forum/read.php?14,815780,833708#msg-833708 Re: Replace timing belts with FireLine https://reprap.org/forum/read.php?14,815780,833708#msg-833708
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warbunniex
its a fusion 3 printer. could try asking them... though i think they may have patented it if i remember correctly. so could always go look up the patent.

Edit: also holy cow. i just saw that motor pulley... thats gotta be some kinda joke for a 6k machine!

What kind of patent could apply to that ???? Cables, strings in similar set up have been used and tried for decades if not centuries ( eg. plotters) !

Indeed, from the video, it is comical ! smiling smiley]]> MKSA Mechanics Sat, 15 Sep 2018 01:51:26 -0400 https://reprap.org/forum/read.php?14,815780,833707#msg-833707 Re: Replace timing belts with FireLine https://reprap.org/forum/read.php?14,815780,833707#msg-833707 MKSA Mechanics Sat, 15 Sep 2018 01:41:16 -0400 https://reprap.org/forum/read.php?14,815780,833696#msg-833696 Re: Replace timing belts with FireLine https://reprap.org/forum/read.php?14,815780,833696#msg-833696
Edit: also holy cow. i just saw that motor pulley... thats gotta be some kinda joke for a 6k machine!]]> warbunniex Mechanics Fri, 14 Sep 2018 16:07:07 -0400 https://reprap.org/forum/read.php?14,815780,833684#msg-833684 Re: Replace timing belts with FireLine https://reprap.org/forum/read.php?14,815780,833684#msg-833684
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The cable is just allowed to walk up and down the drive pulley?
I don't think it walks up and down. I'll confirm.

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Does it make plinky noises when it runs?
The only sound I hear is from the part cooling fan

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How do you keep the cable parallel to the guide rails when it walks up and down?
I haven't paid close attention, but I want to say the string doesn't walk up and down. I'll take a video the next time I run a print job.

-edit-
I was wrong! The string does go up and down the pulley
[youtu.be]

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How long does it run before you have to retighten the cables?
Per the manual, the drive system should be checked every 300 printing hours. The machine is approaching close to ~800hours without any maintenance to the drive system, and I haven't seen any slack on the string.

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What kind of cable does it use?
Not sure what type, but from their brochure, if I recall correctly, it's some kevlar line (will need to confirm).]]> banana_muffin Mechanics Fri, 14 Sep 2018 13:06:52 -0400 https://reprap.org/forum/read.php?14,815780,833663#msg-833663 Re: Replace timing belts with FireLine https://reprap.org/forum/read.php?14,815780,833663#msg-833663 I used a similar printed drive pulley for a while - until the cable destroyed it.
The cable is just allowed to walk up and down the drive pulley? Does it make plinky noises when it runs? How do you keep the cable parallel to the guide rails when it walks up and down?
How long does it run before you have to retighten the cables?
What kind of cable does it use?]]> the_digital_dentist Mechanics Fri, 14 Sep 2018 08:09:56 -0400 https://reprap.org/forum/read.php?14,815780,833621#msg-833621 Re: Replace timing belts with FireLine https://reprap.org/forum/read.php?14,815780,833621#msg-833621 banana_muffin Mechanics Thu, 13 Sep 2018 19:20:46 -0400 https://reprap.org/forum/read.php?14,815780,832559#msg-832559 Re: Replace timing belts with FireLine https://reprap.org/forum/read.php?14,815780,832559#msg-832559
Last May I was in Boston, visited the MIT Museum. There you can see how they used cables for their earlier "robots" in the seventies]]> MKSA Mechanics Sat, 01 Sep 2018 02:35:00 -0400 https://reprap.org/forum/read.php?14,815780,832308#msg-832308 Re: Replace timing belts with FireLine https://reprap.org/forum/read.php?14,815780,832308#msg-832308
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the_digital_dentist

31.0 mm +/- 0.1 mm.

This +- 0.1 mm was what the author talked about as being inexact (but not only this tolerance, but the screw hole itself is wobbly). He used a hair ruler to line up the shaft with the stepper shaft, and the tolerances were about 1/100 mm. But not so important for 3d printing.]]> JoergS5 Mechanics Wed, 29 Aug 2018 01:45:05 -0400