hillzofvalp
100 kW
....,maybe 1/2" is not excessive if you're using soft steel
Maybe this helps
Maybe this helps
The importance of good quality torque plates
- Thread starter NeilP
- Start date
John in CR
100 TW
Harder than the axle is a mistake IMHO, because if something is going to give over time it's better to be the easily replaceable part, and over time anything without clamping is gonna give. That's why clamping is necessary, mandatory in my book. Lot's of width is necessary for all motors IMHO, because the lower power motors have so little flat surface area on the axles, so even if there's less torque, there's less to hold it back.
If you think about it motors with spinning shafts that have the torque at the axle that our dropouts are holding back with our hubmotors will have 1" driveshafts with keyways. Engineers designing those motors would laugh heartily at the typical hubmotor connection to the bike once they look at the forces involved. Just because many of us get away with moderately beefed up dropouts/torque arms, doesn't mean more is overkill.
At least Neil gets it, and maybe all of us need to experience what happens once you start using regen, just like Neil did as did I. We try to help others learn from our experience so they can avoid wallowed out torque arms and/or dropouts, and experience says clamping dropouts are the only adequate solution and there's no such thing as overkill on the width. You really need a nice wide one any to fit a nice size clamping bolt anyway.
A wide clamping surface doesn't necessarily mean a crazy amount of weight. eg My dropouts for Hubmonster have 20mm wide clamping plates which are made of nice hard leaf spring steel only 1/4" thick. They're oriented parallel with axle flats with an 8mm grade 8 bolts to clamp them for great surface contact with the axle. Those clamping plates are welded to 1/4" mild steel plate oriented like a typical dropout.
John
If you think about it motors with spinning shafts that have the torque at the axle that our dropouts are holding back with our hubmotors will have 1" driveshafts with keyways. Engineers designing those motors would laugh heartily at the typical hubmotor connection to the bike once they look at the forces involved. Just because many of us get away with moderately beefed up dropouts/torque arms, doesn't mean more is overkill.
At least Neil gets it, and maybe all of us need to experience what happens once you start using regen, just like Neil did as did I. We try to help others learn from our experience so they can avoid wallowed out torque arms and/or dropouts, and experience says clamping dropouts are the only adequate solution and there's no such thing as overkill on the width. You really need a nice wide one any to fit a nice size clamping bolt anyway.
A wide clamping surface doesn't necessarily mean a crazy amount of weight. eg My dropouts for Hubmonster have 20mm wide clamping plates which are made of nice hard leaf spring steel only 1/4" thick. They're oriented parallel with axle flats with an 8mm grade 8 bolts to clamp them for great surface contact with the axle. Those clamping plates are welded to 1/4" mild steel plate oriented like a typical dropout.
John
hillzofvalp
100 kW
Explain more with pictures the clamping you're suggesting. From previous pic I do not see how it is feasible without ruining my frame completely. Make suggestions or draw to show how it would work in above pictures.
Edit: At this point I would like to go ahead and do overkill to prepare for the cromotor. Using my current shortened axle should be okay as long as It's half engaged, right?
If I absolutely have to I can put in another axle if I can get is for less than a fortune
Edit: At this point I would like to go ahead and do overkill to prepare for the cromotor. Using my current shortened axle should be okay as long as It's half engaged, right?
If I absolutely have to I can put in another axle if I can get is for less than a fortune
Alan B
100 GW
Looks like your frame is already ruined.
Putting a pinch bolt through the end of the dropout just beyond the 16mm point might fix those damaged dropouts.
You sure those are steel?
Putting a pinch bolt through the end of the dropout just beyond the 16mm point might fix those damaged dropouts.
You sure those are steel?
hillzofvalp
100 kW
Chromoly....
I was thinking why not just do pinch bolts and some hardened steel shims or spacers on both faces of the slot?
I was thinking why not just do pinch bolts and some hardened steel shims or spacers on both faces of the slot?
John in CR
100 TW
Here's the right side dropout of hubmonster, the motor Cromotor dreams of becoming when it grows up. Note that SuperV is out of service for finish work, so the axle which has a tap in fit to the dropout isn't fully seated.
hillzofvalp
100 kW
Nice. I wish I had welding experience at my disposal.. Or a friend who could sit down and listen to me be picky about such a critical alignment operation.
The steel on my bike is 4130.
http://www.onlinemetals.com/alloycat.cfm?alloy=4130
The steel on my bike is 4130.
http://www.onlinemetals.com/alloycat.cfm?alloy=4130
Alan B
100 GW
hillzofvalp said:
I would think you want to pull those dropout faces back parallel and into clamping rather than shim them. Butter soft chromoly?
hillzofvalp
100 kW
Well I've already pounded that back into parallel. These dropouts were 10.5mm from the factory.
hillzofvalp
100 kW
Is there a stainless steel that is hard enough for this application? If I were to epoxy on torque plates similar to docs, do I pretty much have to use 5/16-3/8" D2 steel? I would never practically be able to remove the epoxy.. So replacing them... :x
Maybe I could bolt on similar plates?
Maybe I could bolt on similar plates?
Alan B
100 GW
Then add weld material and grind/file back to 10mm, then add the pinch bolt. Maybe weld the pinch bolt nuts alongside so avoid drilling the axle. Drill out the threads in one nut, leave them in the other.
Alan B
100 GW
Typically epoxy can be baked off. Don't know how that would work with Doc's 3M stuff, but a torch would probably remove it long before melting things.
hillzofvalp
100 kW
So you are saying pinch bolt only?
Alan B
100 GW
If those are 1/4" thick chromoly dropouts, and the axle is tight in the slot on the flats and all the way down into the slot, and there is a pinch bolt, I would expect that to be adequate. HOWEVER I haven't done it or analyzed it, so get some other input. Find out how to calculate the stress just to verify it. The pinch bolt really stiffens things so they don't have to be so massively beefy.
hillzofvalp
100 kW
That would be extremely convenient. I could also grind off a little bit to make space to weld in a harder material. I also could do multiple pinch bolts if necessary
Alan B
100 GW
I believe the compression strength of most any steel should be adequate, I would not expect grinding extra would help much. It is the bending that is the problem, or is that steel so soft it is being displaced also? The problem seems to me to be the 0.5mm of slop allowing the axle to partially rotate and concentrate force along a small edge. Concentration of force is how machine tools cut, you need to spread the force out over an area and then even soft steel is adequate.
hillzofvalp
100 kW
If this was adequate, I would be thrilled. I could put two 1/4-20 or m6 bolts on each side. It looks like on my frame the top "stay" is very well supported. I would think that compressing the lower one upward will not put the construction out of whack or stress it too much. The bottom "stay" is just hanging there with little support
Maybe a combination of clamping and using my prototype stainless plate would be the safest option, though that would require mounting a single pinch bolt on the very end edge of the dropout.
Do you think the heat from welding this area will effect my battery pack enclosure? I would hate to have to unload everything (see thread to know what I'm talking about)... I figure it wouldnt
Maybe a combination of clamping and using my prototype stainless plate would be the safest option, though that would require mounting a single pinch bolt on the very end edge of the dropout.
Do you think the heat from welding this area will effect my battery pack enclosure? I would hate to have to unload everything (see thread to know what I'm talking about)... I figure it wouldnt
NeilP
1 GW
In my last post, I forgot to put the second picture of the scrapper mods.
I have been back up and edited my last post to insert the pictures I forgot to insert before. To save you going back here they are again.
These are for a "granny bike" motor. a small unknown motor from a 20Kph bike. At 100volt I have had it up to just over 30 mph. This is the same bike as in the first post of this thread..my test bed frame.
A quick bit of a hack with an angle grinder and a bit of rough welding done in 45 mins or less..Can you tell
I have been back up and edited my last post to insert the pictures I forgot to insert before. To save you going back here they are again.
These are for a "granny bike" motor. a small unknown motor from a 20Kph bike. At 100volt I have had it up to just over 30 mph. This is the same bike as in the first post of this thread..my test bed frame.
A quick bit of a hack with an angle grinder and a bit of rough welding done in 45 mins or less..Can you tell
John in CR
100 TW
1/4" is only sufficient for European and Australian street legal status ebikes.
Alan B
100 GW
John in CR said:
Thanks for your comments John.
Even with a pinch bolt?
What's the stress level in the pinch bolt that would cause a failure??
This looks simple to calculate, has someone done the calculations??
John in CR
100 TW
The numbers would be nice, but I wouldn't doubt that after considering that we aren't mating surfaces machined to fit and the forces involved at such a small radius with these high powered rigs, that a ME would recommend an inch of width per side. Of course, if he was any good at all he would steadfastly object to that kind of connection to the bike.
John in CR
100 TW
neptronix said:
LOL, it's just like with your precious little batteries. Just because you got away with something in the short term is irrelevant to the actual safety. Since you think they don't need anything, why don't you back it up and put a little geared hubbie on a set of aluminum forks and ride it on some cliff-side trails with no torque arms for a nice dose of watch what you recommend.
John
Alan B
100 GW
An engineer would analyze the forces and material properties and decide how much material was required and what reasonable safety margins are needed rather than merely overbuilding it. Nothing wrong with overbuilding, but it is not engineering.
I think hillzofvalp should step up and figure out how to calculate this. It looks like an easy calc to me and I'm not a Mechanical Engineer. It is his bike and his risk.
I think hillzofvalp should step up and figure out how to calculate this. It looks like an easy calc to me and I'm not a Mechanical Engineer. It is his bike and his risk.
Doctorbass
100 GW
Alan B said:
By the way, I asked to one of our Mechanical Engineer at work, to calculate how strong my torque arm set can be with a 14mm steel axel.
I now know that the first thing that can break... is the axel :wink:
The QT100 i choosed is perfect for the high compression strengh made by the small surface of the edge of the axel against the torque plate.
I am 100% confident about this guy.
Over the hundreds of T-A sold from now , none ever broke or had sign of stress :wink:
Doc
