S SYDIEN 4Pcs 4mm Rigid Flange Shaft Coupling Motor Guide Shaft Coupler Connector

I'm sure I'm the only one that's ever used these to do what I did, so take it with a grain of salt b/c this use-case is very much 'not as intended'. I used one of these to make a dirtbike powervalve-actuator-shaft collar. How to explain.. hmm... My old dirtbike, a KX250, 2-stroke, has a mechanism called a power-valve. W/out going into gory detail, this is a set of valves that are mechanically moved by an engine-driven centrifugal spindle as RPM increases. This affects the power-output curve of the motor. So anyway, the output-arm of this spindle normally engages with a 'flanged collar' that looks like a small metal pulley or spool. The arm moves in an arc and pushes/pulls this spool which is loosely connected to a shaft that does the valve actuation via two 'e-clips'. On my bike, this spool/pulley went missing (b/c the outer e-clip failed). The part is no longer sold by manufacturer. Finding used ones is nigh impossible. There's no close-analog part I could find in searching McMaster-Carr and the like. I still search occasionally to see if there is something that already exists. You'd think 'dual-flanged metal spool' would be a common part. So, I made one. I found these items in a desperate search. The 5mm shaft diameter is almost perfect.. I had to ream it out maybe .05mm or so to give it just enough clearance on shaft so it would spin freely. The tricky part was that I had to narrow the 'body' and then weld on another larger-diameter washer so that it would mimic the spool I needed. So, picture one of these with another larger diameter flange on the side that doesn't have one (like a 'round-wing' Tie Fighter). The whole thing, outside of flange-to-flange has to be like 8mm (inner spacing is ~4mm), so I couldn't just use 2 end-to-end. I managed to get it shortened and welded on a flat washer of same diameter... and I'll be damned if it doesn't work! It looks like hell, but it works and at the end of the day, wasn't all that hard to make. Now that I've made one, if I had to do it again, it'd be easier. I now have 3 spares to work with too.

Works

Well made very good quality

These are great for what they are, the only issue I have is the shaft tightening screws are too small. You cannot really use these for anything that has weight, or in any kind of a torque situation. The steppers don't have much torque so they work pretty good for that, if there is rapid movement or vibration - the screws come loose and it then spins and comes off.

I was actually hoping to find flanged shaft collars for a 3/8 inch shaft, but couldn't locate any at a reasonable price, so decided to get these and simply increase the 8 millimeter bore to 3/8 inch. That was easy enough on my drill press. I also increased the size of the mounting screw holes on the flanges. Took me 5 minutes to modify all four pieces to the specifications I needed. Hard to go wrong with this set of 4 when some other sellers are charging this much or more for a single piece.

First the "M3" holes in the flange will not accept a M3 thread. They aren't tapped... maybe they're the right size -- somewhere between 2.5mm and 3mm -- if you were going to tap them yourself. Drilling them out to a full 3mm wasn't really a problem... but then when I went to mount it, it turned out the hole pattern wasn't quite square! And it was closer to 15.7mm than the usual 16mm pattern overall. Out of the four, I think I found one that's close enough to put this prototype together, but I'll have to source this part elsewhere if we turn this design into a kit. They did tap the holes for the set screws along the 5mm shaft. A bit looser than I'd like, but they should hold. Their set/grub screws look fine... the included hex key even seems to have been ground a touch to make sure it can enter them. Lots of burrs, but I could see that in the product photo and was expecting to clean them up myself.

They appeared to be cheaply made, but they were not. The only thing I have against them is the size of the set screws.