In reply to JDH.

Whack a mole forever apparently.

In reply to jwz.

So this is a solved issue? Or did the Plasti-failure put this back in the final 10% that is endless wackamole queue?

In reply to jwz.

Yeah that shit's really stretchy and peels right off.

In reply to jwz.

Eh, drat. What about skateboard grip tape?

In reply to Thomas Sibley.

Based on an earlier suggestion, I ordered some of this stuff https://sundialwire.com/products/tape-12-yard-roll-1-4-self-fusing-silicone-tape?variant=30050321039424 (apparently their last roll, since it's now sold out) and while it hasn't come off yet in one or two tests, it also doesn't seem to be providing the necessary level of friction.

In reply to jwz.

maybe silicone tape? https://esigrips.com/collections/rct-wrap/products/self-bonding-silicone-tape

In reply to jwz.

do you have a workshop that repairs/maintains sailing ships/yachts in your city? Try there. These people do not do online. From my experience only plain old rubber will do. Everything else is most probably useless.

In reply to jwz.

Quick, non-destructive thing to try: Scotch self-fusing silicone rubber tape.

In reply to jwz.

interesting problem. I would try mixing a friction substance, such as fine sand, polyester or nylon fibres, or similar, with metal glue, then brushing on a thick layer into the seating groove, and letting it completely dry.

In reply to jwz.

Ah, that sucks. I've always wondered.

Update: after only a week, Plasti-Dip has proven to be even more bullshit than Sugru.

I have upgraded all the things.

• Tapped new holes and added pulleys for ~270° contact with the wheel;
• Rubberized the wheel using PlastiDip instead of Sugru, which seems more durable. (Had to paint it on with multiple coats by hand -- dipping was too thick and uneven);
• Replaced the cord with "tar twine" (huge hassle since it is 13' up and passes through multiple pulleys);
• Bigger wheel, with more surface area, and also moves the curtain faster.

In reply to jwz.

was here to mention inner tubes, since a 1.75 will have some stretch cut as a ring, but cut lengthwise you could take up the diameter however you like. the ring can conform to the sides and make more contact with the belt. no friction material is gonna last super long, that pulley is designed to use (poly)urethane round belts (they can be cut to length and heat sealed back together) tension has to be added to make them grip better but that also makes the service life of the belt shorter (they stretch.) if you can't change the belt you might have better luck making something like a windlass where the belt passes over the pully a lot more times. the only thing that provides friction in these mechanisms is contact, no material you can put on there will last as long as you hope

Does the wheel spin fast? I had this cheapo idea that maybe you could just put a draw string bag over it.

https://www.greencotton.com.my/product/canvas-drawstring-bag-can203/

In reply to Brent.

You are about 14 years too late with this advice.

It took a long time to get there, but it has mostly been working pretty well, except for approximately-annual nonsense like this current failure.

Having worked in an industry that follows the same UL standards as drapery automation, and knowing quite a bit about the subject, my advice to you is: don't.  They're not very suitable for DIY and hobby projects.  Even smallish electric motors can generate a ton of torque at stall, and the hazards go on from there.  The really gruesome horror stories are about huge drapery systems for performance venues, but still.   I hate to tell anyone that's knee deep in a DIY project "just buy the commercial product", I really do, but I'm going to: you want automated drapes, buy some.

Quality anti-slip tape rated for outdoor use. Some other component will fail before the tape. Bonus: use the rest in the club.

In reply to tfb.

Yeah, as with most things aliexpress, the description raises more questions than answers, but I think the 2:1 shrinkage is the key thing here. At 90mm ID it should go down to 45mm give or take. I agree that buying heatshrink locally, especially with the current US trade situation, makes more sense. Will also ship faster. DigiKey for example stocks some, though by god it is not cheap: https://www.digikey.com/en/products/filter/heat-shrink-tubing/483?s=N4IgjCBcoBwKwAYqgMZQGYEMA2BnApgDQgD2UA2iAGxgwDMdIxcAnAOx1tMhwwsxJm8dt15gESALrEADgBcoIAMpyATgEsAdgHMQAX2IBaAEzIQaSGoCuRUhRAsQkvQZCnIlABb5Mc3J41NAGsnYiozdQATRUNxCFkFSBBuOQBPGXxFTFw0FyA

As far as I can tell, "Inner Diameter - Recovered" here is the diameter it shrinks to. There's some more options at 50mm, but I assume it should be a really tight fit, for as you said shooting under is a good idea.

Mouser has some too, though the more affordable options there have a recovery diameter of 42mm, which is on the tighter side: https://www.mouser.com/c/wire-cable/wire-cable-management/heat-shrink-tubing-sleeves/?recovered%20diameter=42%20mm%20%281.654%20in%29~~44.45%20mm%20%281.75%20in%29&normallystocked=y&rp=wire-cable%2Fwire-cable-management%2Fheat-shrink-tubing-sleeves%7C~Recovered%20Diameter

Arrow Electronics should have some shipping from the US as well, but I cannot figure out for the life of me how to filter by inner diameter on their heat shrink tubing category page: https://www.arrow.com/en/search-result.html?cat=heat-shrink&currPage=1

The good thing about heat shrink tubing is that in this case, if it wears off (and it's designed to be abrasion resistant), then simply cutting off another 4mm onion ring from the tube and shrinking it over is a task of like 5 minutes. No needing to wait for silicone to set.

Tool-dip rubberized coating to immerse the edge (or all but the bore (blocked w/earplug or cork or...) and mounting face) of the pulley into?
https://www.amazon.com/Plasti-Liquid-Rubber-Automotive-Enthusiasts/dp/B0006SL0VO
I'd prefer to do that to a spare pulley, but it's a peelable-with-effort coating. Seriously low effort. Longevity for this application unknown, but works well on high-touch tool handles.

But, I'll echo the mechanic's belt dressing spray.
https://www.amazon.com/CRC-05350-Belt-Conditioner-7-5/dp/B000M8PZB4
Available at local auto parts stores. Even lower effort. Spray the rope with belt dressing (shield stuff around it from overspray!) and see if that fixes it and for how long.

Rustoleum makes an anti-slip paint for similar applications. If you can't replace the string, coat the pulley groove with anti-slip. There are a variety of options - truck bedliner, Tuff Grip (and a variety of other products in the X Grip family) but I think the only real limit is finding a smaller quantity than the usual gallon size. Also, if you can't remove the pulley, masking it is going to be a PITA.

Search term you may not have tried: “square-cut seal”

In reply to David Konerding.

This is what I would try as well

In reply to CounterPillow.

That's a good thing to try, at least.  I couldn't work out from the aliexpress one what the dimensions were, but RS do lots of this, and maybe the 75mm/22mm one (here) would work, or even something bigger, with a shrunk diameter closer to 50mm (but not too close, as you want it to shrink on pretty hard).  That's a UK link because I can't get RS to offer me a US one, but there will be one.  Heat-shrink tubing is fairly widely available: RS are far from the only supplier.

buy the 90mm one, cut 4mm slice off, shrink to fit with heat gun or hair dryer or, god forbid, a lighter. https://aliexpress.com/item/1005005326536181.html

In reply to webley.

Go fuck yourself.

In reply to jwz.

It's the best suggestion here and if you get the correct size it will work fine.  Trust me.. I know what I'm talking about and you don't.

In reply to jwz.

No, not really.  Or at least, not by itself.

But one of the neat parts about a shoulder bolt is that the shoulder is a surface that has been ground to be round, and of a specific diameter.  And there's pulleys that match that diameter.

They even sell them together:  https://www.amazon.com/PATIKIL-Groove-Bearing-5x17x8mm-Bearings/dp/B0D4LCNJST  (the key search term here is "u groove bearing" -- different shapes of these also exist)

Get an M5 tap and a 4.2mm drill bit and some appropriate spacer-bits (Ace Hardware) so it can be aligned with what you have and snugged up, then send it.

(LPT:  Find a chunk of similar aluminum and practice first if tapping holes is new to you.  It's easy to drill and tap holes in extruded aluminum, but broken taps are terrific to deal with.  Always use cutting fluid like Tap Magic; it pays for itself in fuckery-avoidance.)

In reply to jwz.

One thought I had was using regular bolts, extra nuts and small sections of a stainless steel drinking straw.  I discounted it as being fiddley but a trip to a hardware store and you could play around.  But maybe just put the straw sections over the shoulder bolts to be a bit simpler.  Cutting a stainless straw with a hacksaw will be weird but possible.  I have seen "regulation bearing bolts" but I think they're highly specialized and tricky to source.  Maybe just a plastic straw to test it out, that'll work for quite awhile.

What about a 50mm x ring? Something like this https://oringsandmore.com/x-rings-50-52-x-1-78mm-minimum-2-pcs/ The cross sectional shape is like an X so maybe the cord could ride in the legs of the X.

Maybe a polyurethane resin would last longer.

https://www.belzona.com/en/products/2000/2311.aspx

https://silpak.com/products/polyurethane/rubber/