torque arm for X5 hub
- Thread starter curious
- Start date
what voltage are you running ?
and front or rear wheel ? :wink:
and front or rear wheel ? :wink:
This is a project in initial phase. Rear wheel, 3505 (likely) or 3504 (possibly) hub motor, steel frame, 66/33V switchable Dewalt-based pack, oversized controller (search in progress, 100A peak minimum). Need a lot of static torque in 33V mode. Have seen web picture of a Phoenix R1/R2 arms but not really impressed. Open wrench idea is much more appealing but I am not sure I can make it work without welding / torch / machine shop equipment. Maybe I can find some local shop to cut a custom arm out of annealed carbon steel plate and then temper it but it will certainly cost a lot.
Drunkskunk
100 GW
10mm open wrench works great. Make positive its forged, and not cast if you want to weld to it.
a flat piece of 1/8 X1 barstock from Home depot can be cut with an angle grinder to make a torque arm. electric angle grinders are cheap.
100 amps on 66v with a 530X motor is overkill. the motor might spike that on the first few rpm from a dead stop, trying to go up a hill, but would drop back into the 30-40 range for hard acceleration.
a flat piece of 1/8 X1 barstock from Home depot can be cut with an angle grinder to make a torque arm. electric angle grinders are cheap.
100 amps on 66v with a 530X motor is overkill. the motor might spike that on the first few rpm from a dead stop, trying to go up a hill, but would drop back into the 30-40 range for hard acceleration.
I had one idea on those...
The axle has a fairly large diameter right where it comes out of the hub, then it steps down to the threaded part. If you filed or ground flats on the large diameter part so it became a hex head, you could then use a super strong box wrench to fit on the hex. The arm would be on the inside of the dropout. Then it would be a matter of anchoring the other end of the wrench to the stay. If you used a wrench with box ends on both ends, it should be easy to make a clamp that bolts through the end of the wrench. A hose clamp might work.
A box wrench can withstand much more torque than an open end. A 12 point box would give you lots of flexibility in the mounting angle of the arm. It might be necessary to heat and bend the wrench to get the right fit.
Making the hex on the end would be best done with a milling machine, but I think a combination of hack saw, file, and Dremel ginder would do it.
Why don't they just make them this way from the factory?
The axle has a fairly large diameter right where it comes out of the hub, then it steps down to the threaded part. If you filed or ground flats on the large diameter part so it became a hex head, you could then use a super strong box wrench to fit on the hex. The arm would be on the inside of the dropout. Then it would be a matter of anchoring the other end of the wrench to the stay. If you used a wrench with box ends on both ends, it should be easy to make a clamp that bolts through the end of the wrench. A hose clamp might work.
A box wrench can withstand much more torque than an open end. A 12 point box would give you lots of flexibility in the mounting angle of the arm. It might be necessary to heat and bend the wrench to get the right fit.
Making the hex on the end would be best done with a milling machine, but I think a combination of hack saw, file, and Dremel ginder would do it.
Why don't they just make them this way from the factory?
rkosiorek
100 kW
the only problem with a wrench is that it is too thick. most people are running into problems with the width of the motor + freewheel + disc brake or any combination of the 3 to start with fitting into a standard dropout either front or rear.
on the freewheel side there isn't the room and still keep the rim centered with some kind of reasonable dish.
on the other side we need some room for the wires to exit as well as the room for the disc if desired.
it is a good idea but the wrench is just too thick. maybe if they were made from wrenches that were stamped from a metal plate? also if the mating hex shape that was cut into the axle was lightly shallower in depth than the thickness of the plate wrench it would be clamped tightly between the axle and dropout and give it a bit more bite.
elswhere someone posted this picture of a torque arm
http://www.endless-sphere.com/forums/download/file.php?id=5399&mode=view
posted in this thread
http://www.endless-sphere.com/forums/viewtopic.php?p=37310#p37310
just blow up the picture and look at the mounted motor. i think that something like this with the hex idea might be the solution.
rick
on the freewheel side there isn't the room and still keep the rim centered with some kind of reasonable dish.
on the other side we need some room for the wires to exit as well as the room for the disc if desired.
it is a good idea but the wrench is just too thick. maybe if they were made from wrenches that were stamped from a metal plate? also if the mating hex shape that was cut into the axle was lightly shallower in depth than the thickness of the plate wrench it would be clamped tightly between the axle and dropout and give it a bit more bite.
elswhere someone posted this picture of a torque arm
http://www.endless-sphere.com/forums/download/file.php?id=5399&mode=view
posted in this thread
http://www.endless-sphere.com/forums/viewtopic.php?p=37310#p37310
just blow up the picture and look at the mounted motor. i think that something like this with the hex idea might be the solution.
rick
Attachments
Yes, a standard wrench would probably be too thick without some grinding. The flat plate version would be good if the metal was super strong. A 12 point star on the axle, rather than a hex, would be better yet but very difficult to DIY.
Either way, I think the torque arm really needs to hook up to the thick part of the axle and not just on the flats of the threaded portion.
Another idea I had was to drill and tap into the face on the thick part of the axle so you could bolt an arm to the face. If the bolts were flat head and the arm had countersunk holes, it would fit in a pretty small space. This would be a bit of work, but perhaps easier than making a hex. With high grade bolts, the strength should be good enough.
If the face of the thick part had a circle of holes around it (like 6 or 12), and the arm had matching pins that fit into the holes, the pins would be held in by the axle nuts being tightened. The pins would need to be welded into the arm (perhaps brazed would be strong enough). This would be perhaps easier yet, and still allow lots of mounting angles.
Either way, I think the torque arm really needs to hook up to the thick part of the axle and not just on the flats of the threaded portion.
Another idea I had was to drill and tap into the face on the thick part of the axle so you could bolt an arm to the face. If the bolts were flat head and the arm had countersunk holes, it would fit in a pretty small space. This would be a bit of work, but perhaps easier than making a hex. With high grade bolts, the strength should be good enough.
If the face of the thick part had a circle of holes around it (like 6 or 12), and the arm had matching pins that fit into the holes, the pins would be held in by the axle nuts being tightened. The pins would need to be welded into the arm (perhaps brazed would be strong enough). This would be perhaps easier yet, and still allow lots of mounting angles.
rkosiorek
100 kW
i had considered completely cutting off the threaded portion of the axle and drilling and tapping what is left for M10X1.00 cap screws. that would mean that the axle would center on the dropout opening properly. but it would mean that the motor would turn unless a torque arm was provided.
i had also thought of your idea of 5 M4 or M5 flathead screws to bolt on the torque arm. but i am not sure if they would take the shearing force of the torque arm. yes i know that the motor is basically held together with 8 M4 screws on each side but these do not have to take the shear that the torque arm could produce. if the axle bolt ever lo0sened the arm would pivot around it and the holes in the arm would try to cut the screws like a pair of shears.
Gaston (Ypedal) has also suggested using the single 10mm cap screw. this would solve the problem of the threaded part of the axle being too short for all of the stuff we want to clamp with it. if you need it longer - use a longer screw. and the screw can definitely produce more clamping force than the interrupted threads of the existing axle.
ideally an ISIS style crank spline and a torque arm to mate could be almost perfect if we were set up to make such things. but that is just wishful thinking.
rick
i had also thought of your idea of 5 M4 or M5 flathead screws to bolt on the torque arm. but i am not sure if they would take the shearing force of the torque arm. yes i know that the motor is basically held together with 8 M4 screws on each side but these do not have to take the shear that the torque arm could produce. if the axle bolt ever lo0sened the arm would pivot around it and the holes in the arm would try to cut the screws like a pair of shears.
Gaston (Ypedal) has also suggested using the single 10mm cap screw. this would solve the problem of the threaded part of the axle being too short for all of the stuff we want to clamp with it. if you need it longer - use a longer screw. and the screw can definitely produce more clamping force than the interrupted threads of the existing axle.
ideally an ISIS style crank spline and a torque arm to mate could be almost perfect if we were set up to make such things. but that is just wishful thinking.
rick
Drunkskunk
100 GW
the wrench doesn't fit on the inside, it fits on the outside, under the nut.
a 530X is only capable of about 80 Footpounds of torque. thats well with in the range of a good dropout on the rear of a bike, so a torque arm is only supplemental. Since a normal wrench can take a few hundred pounds of torque, its fine sitting on just the flats. the hardened steel axle and the forged wrench aren't ever going to strip and brake, even with only one wrench.
As for mounting, I used mine as the stands for a back rack.
a 530X is only capable of about 80 Footpounds of torque. thats well with in the range of a good dropout on the rear of a bike, so a torque arm is only supplemental. Since a normal wrench can take a few hundred pounds of torque, its fine sitting on just the flats. the hardened steel axle and the forged wrench aren't ever going to strip and brake, even with only one wrench.
As for mounting, I used mine as the stands for a back rack.
rkosiorek
100 kW
from the description i think that he wanted to put the torque arm inside the dropouts. he described cutting the hex into the larger diameter of the axle beyond the threaded part.
your idea is great but it depends on the frame having vertical or near vertical dropouts. not all frames are so blessed.
i think it was knoxie who last year posted some photos of a wrench setup like yours where the torque of the motor not only destroyed the fork but the wrench as well. granted it was a front fork puma that knoxie was tormenting with very high volts and amps but he did manage to do it.
what can also happen is if the nuts loosen a bit the axle with those nice sharp flats can act like a router bit and cut a nice round hole in the dropout without breaking the dropout. i have seen one motor that was not tightened properly and it did carve out his dropouts. he spent a few bucks to have some nice stainless steel dropouts brazed in as a replacement. he bought some new hardened nuts and washers so he could really reef it down. he managed to strip the interrupted thread on the axle. now it doesn't hold at all.
he bought a replacement motor and was a little more careful this time.
rick
your idea is great but it depends on the frame having vertical or near vertical dropouts. not all frames are so blessed.
i think it was knoxie who last year posted some photos of a wrench setup like yours where the torque of the motor not only destroyed the fork but the wrench as well. granted it was a front fork puma that knoxie was tormenting with very high volts and amps but he did manage to do it.
what can also happen is if the nuts loosen a bit the axle with those nice sharp flats can act like a router bit and cut a nice round hole in the dropout without breaking the dropout. i have seen one motor that was not tightened properly and it did carve out his dropouts. he spent a few bucks to have some nice stainless steel dropouts brazed in as a replacement. he bought some new hardened nuts and washers so he could really reef it down. he managed to strip the interrupted thread on the axle. now it doesn't hold at all.
he bought a replacement motor and was a little more careful this time.
rick
recumbent
100 kW
They should supply a face plate like Heinzmann does. :? edit: I'm having trouble compressing the file, sorry.
