Hello all,
We ended up using Tetrix plastic tank tread for our conveyor this year due to some issues with polycord and gates belts, but we want to use gates belts next year.
However, I’ve found that the Gates sprockets are very heavy (we have, i believe, 4"ish diameter sprockets.
Anyone know of lighter belt sprockets?
Those are for inch-based pitch timing belts, the Gates belts from the KoP are 5mm HTD pitch.
SDP/SI sells polycarbonate timing belt sprockets with aluminum hubs in 5mm HTD pitch.
One of the things our team did was lathe our steel pully (at the time that was all they had instock, so we had to go with it) so that it was generally lighter but till maintained everything a pully needs.
The attached picture shows what we do to 60 tooth Gates sprockets to make them considerably lighter. We use a combination of lathe and mill, but you can do it all with either if you only have one, as long as you have a rotary table for your mill.
Keep in mind also that you only need to use a belt sprocket for the roller that is driving the belt, you can make any other rollers out of PVC pipe or any other lightweight round stock you have access to.
have you ever had an issue with the belt falling out of the sprocket?
I’m just wondering because I feel like a flanged sprocket is a safer bet.
Just curious; what issues did you run into with polycord? We managed it fine this season. (Minus the fact our speed was tortoise slow due to being run of the FP gearboxes in the KoP)
The 60T shown is used on our wheels. I don’t think it is even offered with a flange, but then I’ve never looked. The small sprocket on the other end of the belt has a flange and keeps the belt in place. And where the sprocket is in our drivetrain, there’s not enough room on either side of the sprocket to let the belt fall off. We’ve run variations of the same basic design for two years now and have never had a belt come off (~80 matches).
For an application like the OP was thinking about, I’d try to put some thin plastic flanges on the sprocket (made from something like a Cool Whip container lid) or some other sort of spacers to hold the belt in place. The design shown in the picture is not suitable for the application in question, the center hub would need to be different. Picture is just to show an example of what is possible in terms of material removal on the Gates sprockets.
If you move up to wide belts, like the Brecoflex that were popular several years ago as tank treads, you can get them with a “rib” in on the toothed side that will track in a grove in the pulleys.
We use aluminum pulley stock from SDP-SI. We ordered 2 long lengths of it and cut it to the exact length we needed, and then finished off the ends on a lathe. Picture.
We then put the sprockets in 3x1.5" tube. Extra picture.The sprockets are 5mm pitch, 25 tooth. Anything larger than that size is certainly overkill. (I think OD is around 2".)
Reference photo above. Had no issues all year.
