Any Reason To Not Use Syncromesh Cables?

[Bill Havins]

I got the call today that my Rostock MAX is being shipped; this weekend I'll begin the build. I'm excited!

My CNC experience is all based on using ball screws for positioning. My research suggests that syncromesh cables work very similarly (similar mechanical forces involved). Having read through many of the posts on this forum, and having spent considerable time perusing other internet sources, I've begun to consider ordering in the parts to build my MAX using syncromesh cables rather than timing belts.

Are their problems with this plan that I'm not aware of?

Thanks in advance!

Bill

[cambo3d]

bukobot uses this, if they can make it work, i dont see why it wouldn't here.

[Polygonhell]

I got the call today that my Rostock MAX is being shipped; this weekend I'll begin the build. I'm excited!

My CNC experience is all based on using ball screws for positioning. My research suggests that syncromesh cables work very similarly (similar mechanical forces involved). Having read through many of the posts on this forum, and having spent considerable time perusing other internet sources, I've begun to consider ordering in the parts to build my MAX using syncromesh cables rather than timing belts.

Are their problems with this plan that I'm not aware of?

Thanks in advance!

Bill

How big is the smallest pulley you can get for synchromesh, the max uses 15 tooth GT2 pulleys, and you really need the resolution of the smaller pulley.
Obviously you'll need to deal with the belt paths, and they aren't just a motor at one end and an idler at the other.
FWIW I don't think you'll get a significant win over the GT2 belts, but they may be more robust.

[Bill Havins]

How big is the smallest pulley you can get for synchromesh, the max uses 15 tooth GT2 pulleys, and you really need the resolution of the smaller pulley.
Obviously you'll need to deal with the belt paths, and they aren't just a motor at one end and an idler at the other.
FWIW I don't think you'll get a significant win over the GT2 belts, but they may be more robust.

This is what I need to hear ("...I don't think you'll get a significant win over the GT2 belts...").

A quick search of the internet found a number of sources for 15 "groove" syncromesh pulleys (analogous to 15 tooth pulleys) with approximate 1" diameters and .25" center holes. I'll build the kit as delivered and keep the synchromesh idea in the background.

[dbarrans]

1" diameter? That's significantly greater than the diameter of the standard Rostock Max pulleys, and won't do anything good for resolution.

- dan

[Godspeed]

Looks pretty close in diameter to me. you can find a 20 tooth, 10.3mm diameter pulley with a 5mm bore for about 10 bucks. Part number A 6P 9M0602005, click on the part number in the link to pull up an autocad file.
Here is a working link,

https://sdp-si.com/eStore/Direct.asp?GroupID=312


Forgot to mention, I used my calipers to check my Seemecnc pulleys and they look to be a hair over 9mm.

[Polygonhell]

Looks pretty close in diameter to me. you can find a 20 tooth, 10.3mm diameter pulley with a 5mm bore for about 10 bucks. Part number A 6P 9M0602005, click on the part number in the link to pull up an autocad file.
Here is a working link,

https://sdp-si.com/eStore/Direct.asp?GroupID=312


Forgot to mention, I used my calipers to check my Seemecnc pulleys and they look to be a hair over 9mm.

The 15 tooth GT2 pulleys will be exactly 30mm/revolution a 20 groove synchromesh pulley has a 19.4mm pitch diameter (which is the one that matters) which is roughly PI*19.4 = 60mm/revolution so roughly 2x more travel/rev which will increase your top speed but impact precision.
Why does that matter?
Well ignoring the way precision varies on a delta printer for now minimally you have a belt driven Z, with a 30mm/rev gear and 8 uSteps you have a best case Z resolution of ~0.02mm with a 60mm/rev pulley thats closer to 0.04mm, which would be acceptable if it were constant as the head moves horizontally but it isn't on a delta so as the head moves horizontally you get roughly that error in the vertical plane, it's actually somewhat less because errors average out across the arms but you get the ides.

You can work around this, use 16uStep or if you used different electronics 32uStep drivers, you could use 400step steppers etc etc.

*EDIT fixed my math confused Diameter with Radius*