source for wide GT2 belts and pulleys (15mm-18mm)?

[Lamont Cranston]

Does anybody know where to get various GT2 accessories in the wide-belt form factor? Now that I have a magnetic rotary encoder (i.e. smart stepper) I can drive my motors MUCH harder; the 6mm belts have begun to stretch more quickly than usual and I'm pretty sure they'll snap soon.

Search engines don't distinguish between the belt width and various other dimensions, so "15mm GT2" searches turn up a big pile of false positives.

I can confirm that this vendor's 15mm-wide GT2 belts fit nicely; shipping is not too quick but not too slow either, at least to the US:

http://www.ebay.com/itm/221884227725

Robotdigg has a wide pulley, but it's brass (heavy=inertia, also soft: don't drop it!) and worse the bore is an oddball 7.8mm which they don't mention on the sales page:

http://www.robotdigg.com/product/939/GT2-profile-30-tooth-brass-pulley

Checked with them and Robotdigg does not sell any other wide-GT2 products (no belts!)

An affordable source for 5mm-bore, >18mm-wide aluminum pulleys would be awesome.

If none exist I will probably broker a group buy using RobotDigg's customized pulley service:

http://www.robotdigg.com/product/14/CUSTOMIZED-Timing-Pulley-and-Timing-Belt

Let me know if you're interested. It will be just like the brass pulley above but made of aluminum and with a 5mm bore. I plan to keep the inter-tooth setscrew placement, the extra shaft length for a dedicated setscrew region on most pulleys is annoying.

- a

PS, does anybody who Andy Vickers is and what project this is from?
http://www.robotdigg.com/product/970/36-Tooth-GT2-Pulley-Designed-by-Andy-Vickers

[Michael Anton]

Are you using steel core belts in combination with too small a pulley?  That would certainly cause problems in short order.

Personally, I've never noticed any belt stretch on my 3D printer which now has at least 1000 printing hours on the same set of belts.  At one point I ran the belt on my Y axis (the bed moves in this axis) so tight that the stepper shaft broke eventually, since the shaft on the other side of the pulley was unsupported.  Interestingly, the shaft broke between the rotor, and the inside of the front bearing, so looking at the motor, you couldn't even tell.

Mike

[Danh Trinh]

Try Stock Drive Products:

https://shop.sdp-si.com/catalog/

[Oz-Ron]

The reason for a brass pulley is far better durability over the softer aluminium type.

Commercial desktop machines use them to preserve the zero backlash benefit of the GT2 tooth profile that deteriorates with wear.

 

Combined with the mass of the Nema23 rotor, the slight increase in total rotational inertia is worth the benefits the quality pulley for a machine that is working hard.

 

Not sure where the 7.8mm bore came from, but they fit the 8mm shaft Nema23 1.3nm motor quite nicely. See attached.

It is best to go to the 8mm shaft motor because plenty have snapped the smaller diameter shafts with load flexing fatigue that can be associated with stronger belts & tension.

 

Robotdigg also has the matching 18mm wide GT2 belt available on request at a reasonable price.

 

Ron

[Lamont Cranston]

On Dec 27, 2016, at 9:12 PM, Danh Trinh <dttw...@gmail.com> wrote:

Try Stock Drive Products:
https://shop.sdp-si.com/catalog/

According to their website the widest they stock is 9mm, see screenshot below, left column, options are 3.0, 6.0, 9.0 only.  If I'm using their fancy AJAXified website wrong a direct product link would help.

Thanks!

[Lamont Cranston]

On Dec 27, 2016, at 10:24 PM, Oz-Ron <ronedw...@gmail.com> wrote:

Robotdigg also has the matching 18mm wide GT2 belt available on request at a reasonable price.

According to their sales staff they do not stock them.  See screenshot below.

[Lamont Cranston]

On Dec 27, 2016, at 10:24 PM, Oz-Ron <ronedw...@gmail.com> wrote:
>

> Combined with the mass of the Nema23 rotor, the slight increase in total rotational inertia is worth the benefits the quality pulley for a machine that is working hard.
>
> Not sure where the 7.8mm bore came from, but they fit the 8mm shaft Nema23 1.3nm motor quite nicely. See attached.
>
> It is best to go to the 8mm shaft motor because plenty have snapped the smaller diameter shafts with load flexing fatigue that can be associated with stronger belts & tension.

Ah, okay, this makes a lot of sense, I can imagine that most machines that need the wide belts are driven by NEMA23 or larger motors, so the pulley is aimed at those motors.

Thanks for clarifying. I had been considering moving up to NEMA23 motors but was waiting to try the CoreXY drive approach first (if I stick with it then motor mass does not matter as much and larger motors are an easy decision).

[Oz-Ron]

For Nema17 motors GT2 any wider than 9mm would be completely unnecessary. 

This 9mm setup is what I adopted for my Alu Core-XY Printer design using large Nema17’s. (attached PDF)

 

Due to the increasing PnP head mass (with migrating all the valves & motor drivers etc) I quickly went to some decent power driving the main axis.

Nema23 - 2nm (dual shaft) on the Y axis and Nema23 1.3nm on the gantry X-axis.

 

My first mistake was to use T5 10mm belt / pulleys initially due to their strength and power handling.  Problem is they introduce some small backlash which is not so small for 0402 parts etc.

 

To maintain the performance and improve the accuracy, the wider GT2 setup was the answer.

 

I was able to source the wide pulleys and matching belt from Derek with about a four week lead time. (see attached)  The Belt is 18mm and compare it to 9mm readily available.

 

My only advice is to try and start where you want to end up with your design and then work back to the beginning.

 

Have fun.

 

Ron

[Danh Trinh]

try:

https://shop.sdp-si.com/catalog/?cid=p343