mr.electric said:
I will open the motor and take pics after work today. I feel that adding a spacer like crossbreak mentions should solve the grinding. Normally the axle is fixed into the hub because the stator is sandwiched and has no axial play. Now that the axle is free it has endplay and could probably cause the rotor to contact something else in the motor. That is my theory anyways. I may need to add a c clip some where too. I have had good luck cutting c clip grooves in motor shafts by spinning the axle and touching a hack saw blade to the spinning axle.
Ebike building is such an awesome hobby! I really enjoy the discovery part of it.
I have in past years I have cut quite a few snap ring grooves. There are much better ways to cut a groove than to touch a hacksaw to it while it is turning. It is almost guaranteed that the groove won't end up where you wanted it. The exception to this is to put a shaft collar around the shaft and cut against the side of the collar, but you have to have collars for every size shaft. You can make a quick v block to use with a variety of shaft sizes from a piece of steel angle iron. 1/8" thick is fine, but leg lengths need to be 3 or more times the size of the shaft you are working with. The length is not special, but if you cut it the length of the shaft you are using it will work real nice. About 1/3 of the length from one end tack weld a piece of 1/4" ~ 3/8" key stock that is about a 1/2" longer than the width of your vise jaws to the root of the angle on the outside. You do have a vise? Mama couldn't have put a meal on the table at our house without a good vice
Don't get real wild with the welding or you will warp the angle. Just a good fat tack on each end will work fine. That way you won't warp it and the weld won't get in the way of the vise jaws. The key is just to hold the jig in the vise. Over about the middle of the key lay a square butt scale (combination square for carpenters
across the ends of the angle legs. ACCURATELY make two marks that will establish a line 90° to the root of the angle. Use a scribe, jeweler's file or an extra sharp Sharpie marker. Lay the square on the outside of the angle legs and extend the marks from the edges to the root. Do this carefully too. If you don't do it right the first time, it won't get any better with age. Next prep a new 24T Bi-Metal hacksaw blade by running a sharpening stone down both sides the blade to dull the set of the blade. This will keep it from wearing out your jig. It also will make it suck for just cutting metal off, so just keep it for the jig. Carefully cut from the edge of the legs toward the root of the angle for about 1/3 the distance. Do this carefully, one side at the time. Now is not the time to kill the piece. Finish off by running the blade through both slots at the same time. If you did it right there will be little drag. You have finished the jig. I could have built three of them in the time it took me to write this
I bet now you think you know how to use the jig, but I will pass on a few tips that will increase accuracy and ease. When you mark for your groove use an Extra Sharp Sharpie marker. They are about the same width mark as most smaller circlips. You can usually mark against a hub or sprocket easily with them. When you mark the shaft, put another short mark across the original mark down the length of the shaft. This mark will help you remember if you have been around the shaft 2 or 2-1/4 times. Lay the shaft down in the angle in which ever side lines up the mark with the slot and supports most of the shaft, but leaves a little bit hanging off the end. Now you know why you didn't put slot in the middle of the angle
From now on the instructions are for right handed people but I'm sure you South Paws are use to adjusting. Clamp the jig in the vise with the shaft on your left. Align the mark on the shaft with the slot in the angle. Now go get the small pair of visegrips you forgot to bring. Might as well get the hacksaw too. With your left hand clamp the shaft in the jig with your left thumb on the shaft and your finger around the outside of the jig. With your right hand clip the visegrips to the angle so that right end of the shaft touches the side of the jaw of the visegrips. You did adjust the visegrips for the angle? That's OK, I usually forget too :wink: Put the hacksaw blade in the slot and take 3 ~4 strokes, turn shaft a few degrees while holding it against the visegrips, re-clamp with thumb.......repeat. Once you have been around the shaft a couple of times, you can usually just turn the shaft with your left thumb and forefinger and kind of take light polishing cuts to finish up. I have also found that using a close quarters hacksaw that supports the blade by one end and using the blade in a pulling cut works well too.
A word about circlip grooves. They are usually square. They are as deep as they are wide. DON'T CUT THEM TOO DEEP! It is better to err on too shallow than too deep. A circlip will not stay in a groove that is too deep very well, even if you tighten them up. You've been warned! If you need to cut a wider groove, try to offset the shaft a little and cut again. Make the second cut it very little pressure and finish off with jeweler's files. If you need a circlip to hold a larger load, use two with the ends turned 180° apart. Grooves are usually .002" ~ .004" wider than the clips that go in them. If you need a really tiny groove, make a jig for a 32T blade that has the wave set ground off both sides. With external circlips, the smooth rounded edge should be against hub or bearing inner race. For internal circlips. the smooth edge goes against the bearing outer race.
Over the years I have built dozens of these jigs, but sadly I don't have a single one to photograph for you. I have given them away, loaned them with no return or otherwise lost them. I no longer have a need for one but, almost wish I had just built another one just to show how without having to describe in such detail the process. At one time I thought about trying to make a cutter like a tube cutter to cut square grooves, but alas I don't need to do that anymore either. But if I had cut one in the field, I know how to do it quick and now you do too
By the way, the jig works good for drilling holes in shafts in a drill press too. Especially if you are careful welding the key on the bottom and use a 1/2" or 5/8" key.
bØb
It is hard to get a handle on all the forces that are caused by a mid drive mounted on the chain stays, as it is in mr.electrics bike. I have found it is best to think of torques and linear forces separately. The torque generated by the hub motor is converted a linear force by the chain sprocket (more on this latter). This torque is independent of the linear force of the chain. The bending of the mount is caused by the reaction torque of the hub motor case. Ultimately the reaction torque appears all along the chain stay until it reaches the rear axle, which is supported by the wheel. Where the lever arm is short, up near the mount, there can be significant bending. This bending can be minimized by stiffening the chain stay. High power motorcycles sometimes have a diamond structure swing arm on the drive side. But, we don't want the bike to look like a motorcycle. Another solution is to conduct this reaction torque (bending moment) to other parts of the frame. A stiff torque arm (the dreaded word) from the motor mount to the area where the seat stays, seat tube,and top tube meet, helps to distribute the reaction torque thru the rear triangle, and the rest of the bike structure. The torque arm also takes the bending stress off the bottom bracket welds. 
