Tuesday, September 19, 2017

Comparing Gates LL2MR09 and Chinese 2 mm Pitch Glass Core Belts

I recently saw a couple pictures someone posted of two identical prints, made on the same machine with the same gcode file, one using very inexpensive Chinese import glass core GT2 belt and the other using a more expensive Gates belt.  I was impressed by the reduced ringing in the print made using the Gates belt, so I decided to try this experiment for myself.  Unfortunately, I've lost track of the link to those pictures.

I located a source and ordered 50 feet (the minimum quantity that Gates distributors will sell) of the Gates LL2MR09 belt (about $2 per ft. shipped).

One of the things that has always bother me about the Chinese belt was that there are exposed glass fibers along its edges.  Well, the Gates belt has that, too.  Both belts are neoprene with fiberglass core, both 2 mm pitch, and both 9 mm wide.

Part NumberLL2MR09
Pitch2 mm
Top Belt Width per strand (mm)9
Tensile CordFiberglass
Core MaterialChloroprene
Fabric CoverNylon
RMA Oil and Heat ResistantYes
Min Order Qty50 ft
Max Cont Length (feet)300 ft
Product Number93960052

The Gates belt has nylon facing on the teeth which Gates says decreases wear and increases the life of the belt (and pulley?).  Gates also specifies an operating temperature range of -54 to +85 C, so it should be fine inside a heated enclosure for printing ABS.  I was unable to locate any operating temperature range spec for the Chinese belt.

The Chinese belt doesn't seem to have a nylon facing on the teeth, but I can see what appear to be the ends of threads embedded along the tooth surface under a microscope.

Gates belt specs

In the following photos the Gates belt is on the bottom and the generic Chinese belt in on the top.

Chinese belt on top, Gates belt on the bottom.  The gates belt has nylon coating on the teeth.

The chinese belt, top, appears to have fibers embedded in the tooth surface, and the teeth look slightly larger than the Gates belt teeth.  Glass fibers (brown) are visible on the edges of both belts.

Glass fibers are visible in the edges of both the Chinese and the Gates belts.

Notice there are 17 glass cords in the Chinese belt, top, and 20 in the Gates belt, bottom.  Cord diameters appear to be about the same, spacing between the cords doesn't appear to be well controlled in either of them.

One minor difference is that the slicing of the Chinese belt doesn't seem to be particularly accurate.  If you watch the edges of the belt as it moves on the printer, they seem to move up and down as if the top and bottom edges aren't parallel everywhere.  The Gates belt doesn't do that.

I ran some print tests and there didn't appear to be any difference in print quality.  Maybe the parts I printed weren't good for showing the differences.  I'll be trying more prints and if I run into anything that reveals a big difference I'll post it here.  It was enough effort to swap the belts that I don't expect to be doing it again without a really compelling reason.

This video shows one of the test prints- I turned up junction deviation to 0.2 (from 0.05) to induce ringing, and made the straight runs long enough to allow a peak speed of 250 mm/sec.  I used the same gcode with the only difference between the prints being the belts in the XY stage.  To my critical and microscope assisted eye, the prints are essentially identical.  The ringing looks the same, the layer registration at the corners looks the same.  Meh.

UMMD printing ABS at 250 mm/s from Mark Rehorst on Vimeo.

In the short term, these belts seem to perform pretty much the same, but print quality isn't the only criteria by which to judge a belt.  If one belt outlasts the other and the drive pulleys used with one or the other last longer, one belt or the other might be better.

1 comment:

  1. Very nice post! Thanks for the analysis. Likes like belt longevity and less stretch are the only real benefits (if even those).


Leave comments or a questions here and I'll try to post a response as soon as I can.