hillzofvalp
100 kW
Finished product here. I need to weld them on this week.. Can't wait to be running FINALLY.
The importance of good quality torque plates
- Thread starter NeilP
- Start date
hillzofvalp
100 kW
I was informed that it may be a bad idea to weld this on. Why would it? There are tons of places to use tons of fill rod
NeilP
1 GW
Those have to be the best torque plates seen here so far.. well done
As for nto welding...??? localised heating of the frame..stress cracks..early failure? but all tha can be avoided be de stressing the area..reheating the whole and slow cooling I would have thought. I would certainly weld them on
As for nto welding...??? localised heating of the frame..stress cracks..early failure? but all tha can be avoided be de stressing the area..reheating the whole and slow cooling I would have thought. I would certainly weld them on
hillzofvalp
100 kW
Problem is that I would have to strip the frame and put it In someone's oven.. Do you really think fractures will be a problem with 4130?
TonyReynolds
1 kW
Would brazing have any advantages over welding? Might be less stressing to the frame? Can one braze stainless to chromoly, or do the materials being brazed have to be the same?
hillzofvalp
100 kW
This isn't stainless.. it's a harder carbon steel of some sort. I just air grinded it so it's clean and shiny
Maybe epoxying it on would be the best idea.. however, I want the original 1/4" to be built up a little bit to the correct 9.9mm dimension,, because the pinch bolt will be pinching the frame and the extension plate. If I used epoxy, I feel like that flexing action would cause it to break off...?
brazing still requires a significant amount of heat.. so idk if it would have any benefit from the perspective that the heat treatment will get much worse
Maybe epoxying it on would be the best idea.. however, I want the original 1/4" to be built up a little bit to the correct 9.9mm dimension,, because the pinch bolt will be pinching the frame and the extension plate. If I used epoxy, I feel like that flexing action would cause it to break off...?
brazing still requires a significant amount of heat.. so idk if it would have any benefit from the perspective that the heat treatment will get much worse
NeilP
1 GW
hillzofvalp said:
Nah. Here is what I would do if I was worried about this.
Maybe pre heat the area around the weld with gas...even a propane burner enough.
Weld and then as it cools usea ball point type pein hammer along the weld as it cools.
You could even re heat the area with a the propane burner immediately after welding.
The cool slowly by covering the weld in pre heated sand.
But really that is all a bit overkill for welding to what you are..thin section ...but it is the basic technique I was taught years ago for welding to any material that is likely to fracture on cooling...thinking of cast iron here..but the technique will go across to to normal steel too.
You are just trying to remove large localised heat differentials, and rapid cooling.
no need for using an oven, locall area with gas heating is enough
Otherwise, drill, thread and bolt it
John in CR
100 TW
hillzofvalp said:
I'm one who has doubted this epoxy stuff from the beginning, and I just got confirmation Sunday. 3 years ago I epoxied on a 4.5"OD 1.25"ID aluminum disc made from 3/8" plate to which I had a FW thread welded, and that's what held my single speed FW on until 2 days ago. This is on my cargo bike and it never saw much in the way of real force, since it's a feet forward layout and my bikes are electric first. Both surfaces were well prepared and roughed up. I used a pretty good DOW epoxy, maybe not as good as the stuff DrBass uses, but it wasn't ever the absolute strength I was concerned about, especially with 14sqin of surface area bonded. What I always worried about was the thermal effects over time and differences in coefficients of expansion weakening the bond, but my install wasn't a critical one so I went ahead with it because I had no means of welding AL. My worries were valid and just a slight push on my pedals Sunday twisted the thing right off.
That was AL epoxied to form fitted AL. There are people epoxying a nice steel torque arm to bike paint over AL, and a much smaller surface area than I used. Please include some kind of mechanical fastener along with the epoxy.
John
edit- You're right, there's no way epoxy will work with a clamping torque arm anyway.
hillzofvalp
100 kW
Idk guys. Doc's claims are pretty impressive. I just epoxied it on. I haven't decided whether I will attempt to also add a mechanical connection, though once every thing is epoxied on that is much easier to do (get alignment and such). I think that my setup allows for much greater surface area.. the pics may explain.
Thanks, Doc, for introducing me to the DP420 method. I have faith that if this fails, the original frame will save me, and the lips on the frame and the pinch bolt will hopefully keep the axle somewhere on the frame
because I preloaded the gap to about 9.89mm (my axle is 9.9mm) I don't think there will be excessive sheer like the kind you are suggesting will happen. I think the final width of the slot will match that of the cold-set (and epoxy reinforced) dimension. I will have to lightly tap the axle in
Thanks, Doc, for introducing me to the DP420 method. I have faith that if this fails, the original frame will save me, and the lips on the frame and the pinch bolt will hopefully keep the axle somewhere on the frame
because I preloaded the gap to about 9.89mm (my axle is 9.9mm) I don't think there will be excessive sheer like the kind you are suggesting will happen. I think the final width of the slot will match that of the cold-set (and epoxy reinforced) dimension. I will have to lightly tap the axle in
I'm also very skeptical of epoxy, even in the doctorbass torque arm situation.
It just does not calculate to me that an epoxy can be as strong as steel or aluminum.
I don't care how strong the epoxy is; you still have something like a centimeter of contact surface between the metal part and the epoxy., rather than a quarter inch of steel which diffuses the load across the entire metal surface.
I'm not an engineer, just a skeptic. I really think you should bolt or weld things on whenever possible and think of using any kind of epoxy as a 3rd and last option.
It just does not calculate to me that an epoxy can be as strong as steel or aluminum.
I don't care how strong the epoxy is; you still have something like a centimeter of contact surface between the metal part and the epoxy., rather than a quarter inch of steel which diffuses the load across the entire metal surface.
I'm not an engineer, just a skeptic. I really think you should bolt or weld things on whenever possible and think of using any kind of epoxy as a 3rd and last option.
Alan B
100 GW
Even one good screw through there should be good insurance.
Doctorbass
100 GW
Just remember... 8)
If on one inch it can hold 145 Lb-ft torque.. imagine on a torque arm with 2+ sq in
All my ebikes are using torque arms with this epoxy... and good parts of them are extreme build...
no worie i'm not a 3M reseller... just someone who discovered how really it is strong!.. at home... and at work for soem aerospace projects
[youtube]GUQWHht9NMA[/youtube]
Doc
If on one inch it can hold 145 Lb-ft torque.. imagine on a torque arm with 2+ sq in
All my ebikes are using torque arms with this epoxy... and good parts of them are extreme build...
no worie i'm not a 3M reseller... just someone who discovered how really it is strong!.. at home... and at work for soem aerospace projects
[youtube]GUQWHht9NMA[/youtube]
Doc
hillzofvalp
100 kW
It's actually about 10-12 cm^2 metal to metal contact JUST on the flat side. The edges also have some metal to metal contact in the lip.
The side with the derailleur hangar will have more like 14 cm^2 contact on the flat portions.
edit: it's probably close to 8-11 cm^2
The side with the derailleur hangar will have more like 14 cm^2 contact on the flat portions.
edit: it's probably close to 8-11 cm^2
Doctorbass
100 GW
hillzofvalp said:
no worrie.. even if your ebike is crashed in sandwich between two big 12T truck... everything will fall apart except the torque arm on the frame :lol:
Doc
hillzofvalp
100 kW
Lol... your humor will never fail.
hillzofvalp
100 kW
So I have my motor in my frame after about 24hrs... and it is a very tight squeeze after pinch is applied. I can only fit the nut on each side.. if I use nord-locks I will only get half engagement of the threads. Do you think this is okay for this application given that I have pinching dropouts? My cromotor will not have a short axle (cut stupidly on my 9c), and this motor is seeing 3500W peaks.
I now have .5" of dropout, and I filed the slots so they were parallel and about 9.8-9.9mm. edit: I also checked if dropouts were in alignment with frame by using the gyro readings in my phone (made comparisons will seat stays). within .1 degrees on first try! must have good eye! I will add an insurance bolt when I have the motivation...
I now have .5" of dropout, and I filed the slots so they were parallel and about 9.8-9.9mm. edit: I also checked if dropouts were in alignment with frame by using the gyro readings in my phone (made comparisons will seat stays). within .1 degrees on first try! must have good eye! I will add an insurance bolt when I have the motivation...
hillzofvalp
100 kW
Actually, I just tried tightening them down.. and it felt pretty solid.. one of them wasn't as bad as I thought. probably 70% engagement on one and 50% on the other. Doesn't feel like it wants to strip. Also tightening the pinch AFTER tightening the nord locks seem to really preload the nord-locks. This is probably because when I tighten it the dropout slides down the very edge of the lip on the axle... Or at least that's my theory. Maybe .010" on each side.
hillzofvalp
100 kW
AFter about 20 miles, the epoxy has pulled away from the torque arm in the area closest to the pinch. I guess this is going to mean adding two 4mm bolts on each side of the dropout to keep the crack from spreading to the critical areas. Pictures to come. MAybe the pinch isn't even necessary with the nord locks.
TonyReynolds
1 kW
hillzofvalp said:
If you look at the videos for Nord-Locks, they just seem to be very secure; no loosening with vibration...
hillzofvalp
100 kW
Bad news. The epoxy failed me. What happened is that as I tightened the axle down on the frame, it wedged the dropouts apart. the pinch bolt didn't help either.Luckily I did not experience a catastrophic failure since I had the safety bolt in. It is possible that I didn't glue the guy right.
Now I'm thinking of brazing it on to the frame. I am thinking about welding, but I'm worried about ruining the heat treated areas surrounding the dropouts. Also I'm unsure if this no-name steel will weld well to the 4130 frame.
THe other side appears okay. no wedging effect. I tried running those washers before but they just flattened out to the point of running over the OD of the axle.
Now I'm thinking of brazing it on to the frame. I am thinking about welding, but I'm worried about ruining the heat treated areas surrounding the dropouts. Also I'm unsure if this no-name steel will weld well to the 4130 frame.
THe other side appears okay. no wedging effect. I tried running those washers before but they just flattened out to the point of running over the OD of the axle.
MadRhino
100 GW
I've been feeding 150A to a motor fitted in glued on dropouts (steel on alu), without even a small crack in the epoxy. There must be something wrong with yours, either the design or the adhesion process.
hillzofvalp
100 kW
THe other one seems pretty solid. I might've rushed one of them and didn't clamp it right/didn't get ratio right/ didn't let alcohol evaporate long enough. Biggest problem was that I didn't receive a plunger from mcmaster so I made my own out of a taped allen wrench to screwdriver. I will give it another go (by weight), because I really don't want to heat this frame.
You have to be careful though because just because it looks solid doesn't mean that it is. the epoxy forms a perfect mold around the part and I can slide it back on and bolt it on and it feels solid... even with one bolt.
You have to be careful though because just because it looks solid doesn't mean that it is. the epoxy forms a perfect mold around the part and I can slide it back on and bolt it on and it feels solid... even with one bolt.
MadRhino
100 GW
I see two potential reasons for failure in your pic.
First, a pinch dropout should not be glued in the mobile area. I see that when you tighten the pinch, the glued surface has to move.
Second, surfaces must be roughened. I see shiny surface that I wouldn't trust for reliable adhesion.
First, a pinch dropout should not be glued in the mobile area. I see that when you tighten the pinch, the glued surface has to move.
Second, surfaces must be roughened. I see shiny surface that I wouldn't trust for reliable adhesion.
hillzofvalp
100 kW
I roughened it with dremel engraving bits... but I guess not enough. I am going to use the bolt to pinch the corner next time. Last time I added the bolts later after I had used vice grips.
gluing the pinch must not be okay ONLY because it begins to peel the epoxy back beyond the fulcrum (axle) point, which can ruin it everywhere. I do see evidence from rust marks that there was some water ingress
gluing the pinch must not be okay ONLY because it begins to peel the epoxy back beyond the fulcrum (axle) point, which can ruin it everywhere. I do see evidence from rust marks that there was some water ingress
psycholist
100 W
MadRhino said:
+1
I suspect this is the main problem.
