Not use a clamping type of attachment so the shaft does not get damaged.you can get different bore and other sizes using flexible shaft couplings. By ing this you get around counter boring eparate shaft collars I like clamping collars so the shafts don’t get damaged. Keyways are good too you still have to cut the shaft and broach the bores
rc model gas engines usually have taper with woodruff key. The issue is hubs are often aluminum. These expand as thy get hot causing deformation of the taper this then let’s the nut come loose resulting in thrown props among other things. I’ve been through this issue a number of times I’ve made steel hubs with adjustable timing rings holding magnets . By careful design a great deal of the steel weight can be removed without wearing the hub . Years ago I designed a number of hubs in steel that were within a few grams of aluminum monsters I YHINK there are still at least three on engines I still have . These have taper and woodruff keys I made a special puller for these too. In a box in Rc stuff I YHINK . They actually ere easy to service.
I have beam type shaft coupler coming for the engine to engine coupling by the time I’m done I’ll have several flexible vibration absorbing couplers to try. I’ve used all of them in various applications in industry. So far the beam couplers are pretty good. I’ve found they don’t take to high shock loads well but it’s just my experience they are supposed to be ok for this but when you have machine crashes bets are off . The weakest link looses hitting a retaining screw with a boring bar doesn’t do them any good either . I have old ham couplings coming to connect the eccentrics to the crank shafts . I have a single test beam coupling for testing as it was the only one available at the time . It fits perfectly and will have almost no load on it . It mainly a way to couple the eccentric to get crankshaft and provide adjustment . Once everything is back together I’ll begin testing and come up with setting numbers . I’m trying to repair the crankshafts now they won’t be like new but serviceable .
I like this solution of a clamp collar bolted to the hub. You can up size the hub screws to #8's for some more security.
ive got at least 6 iterations of clamping devices to clamp the eccentric and flywheel to the shaft I’ve got one that does both but additional ones are almost a month out I did some rethinking and came up with a coupling instead. These should be here today I even have some shaft collars that are split clamping both the hub or eccentric to the shaft . Also have flexible couplings to couple the two engines together. Even have a dead level and flat mounting surface so the engine crankshaft bearings are in slight also have a straight line up rod or bar to position the engines dead in alight. This all works well the crankshafts are longer on one end than the other so I’m almost out of room on the short end. The solution is a split coupler on one end and shaft extension on the other. I think there are at least 6 items to return to Amazon as they are items I didn’t order or were not what I did order . I’m think I’m just going to have to take these out to my sons shop and sit down and make exactly what I need. This should be easy. Chilertern has sold a bunch of thes engines so they have to be right but I’m just making thing complicated. I don’t like the set screw attachment and already had issues with it I see lots of engines with the same features but I don’t hear of issues maybe I’m just doing something wrong . I like to have things stay together an run when I need or want . I don’t like constant repairs or adjustments . I can’t complain about the engines there are lots of parts and every one has fit perfectly it just these set screws that have made this less than perfect . I’ll get it done one way or the other. It’s just fighting me all the way . I’ve had countless interruptions and now more estate issues .
clever idea
That’s a good point. There is a coupler between ebgines but it’s a nice one for vibration and intermittent loads as well as reversing loads . I also have some vibration absorbing ones with urathane spiders . I’ve used these in machine automation but not this small. I got sidetracked today so I’ll get into assembly tomorrow. I also have a number of split collars that can be counter bored . Possibly on both sides I just got them today I’ll sort and do some measuring tomorrow .
all of the clamping collars and couplings I have now have at least 1 or 2 3 mm clamp screws . Some clamps are split on one side but essentially clamp all the way around when tightened. As a set screw or grub screw a single 3 mm screw just is not going to work, and has already been proven I’ve seen others get away with this but I suspect they don’t run the engines long enough or often enough . I had a tough time getting the flywheel off the crank without causing more damage than what had already occurred. The single stainless screw had a damaged thread. I didn’t want to unscrew it through the brass flywheel so I managed to work it enough that I was able to get the flywheel off then I took my dremel with a very small stone and reached in the bore and ground the end off so I could unscrew the thing .it’s a trick poking a grinding stone in a 6mm bore especially with double vision but it worked ok so the thread hole is preserved fo some unknown purpose later I guess I just had the by weekly blood test so that’s the interruption for today . Now back to work . I have some split collars that are a bit larger diameter so I’ll see if I get these counter bored I’ll be able to use a collar on each side of the flywheel so it should stay in place better . The eccentric only allows for 1 clamp b it should not see large torque and it turns very smoothly. Especially as it is three piece with flat head screws locating the inner flange to the crank bore . I assembled these with a 6 mm pin representing the crank so they did fit nicely . All ther is i the hub to grip with the collar or what ever clamp I use . I thought about remaking them with a built in clamp but I just don’t think I can reproduce the tolerance and precision they have with our equipment. It’s a fussy thing as it is the finish on them is flawless almost polished . The threaded holes are blind and appear as cut with the cnc rather than done by tap with trimmed blind end . . I’m goingvto revisit them later .
