Review my clamping L bracket torque arm

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auraslip   1.21 GW

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Review my clamping L bracket torque arm

Post by auraslip » Sep 21 2011 7:37pm

Sorry for the messy picture. I hope it's enough to show what I have in mind. Basically the axle is clamped between 1"x1/8" L bracket and a floating 1/4" plate. The L bracket is secured to the drop out with m4 screws like on dogmans steel frame bike.

The reason for this strange design is that I need a freakin worry free torque arm, and john has pounded it into my head that the only worry free torque arm is a clamping one. Also, I was having issues clearing the derailleur with more standard designs.

Image

My worry with this design is that everything will rest on 4 (2 per side) m4 screws bolted into thin aluminum drop outs. And at poor locations too. I can just imagine them snapping while jumping off a curb.


This is driving me nuts ~ I've been working on it for three days now, and can't come up with a design I'm happy with.
Last edited by auraslip on Sep 22 2011 3:33pm, edited 1 time in total.
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auraslip   1.21 GW

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Re: Review my clamping L bracket torque arm

Post by auraslip » Sep 22 2011 3:32pm

What ever. I'm just going to go with a design closer to the original.

Image

L brackets provide monster grip on the every available part of the axle flats. Pretty sure even 1/8" should be fine for the L bracket.

Added the top bar that clamps to the chainstay so I don't have to worry about the AL dropouts themselves breaking from torque.


Been thinking about how to safely drill the L brackets to the dropout and concluded that I can't. I'll drill it out for guides, and then use docs epoxy to bond it completely to the dropouts rather than in just two small spaces.
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Re: Review my clamping L bracket torque arm

Post by neptronix » Sep 22 2011 3:57pm

hmm...

If you do give up, it looks like you have a flat section on your dropouts which is good. You could go with my method. I've pumped 2800w through it without so much as a tiny scratch on the frame and torque plate.

http://endless-sphere.com/forums/viewto ... hilit=4300

As long as you have two bolts on each side, a big ol' steel plate will work fine. My plates are definitely overkill too.

Two holes is definitely enough. There should be 3 holes on the disc brake side too. As long as clearances are super small and nothing is shifting about, you should have yourself a very strong mount.
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Re: Review my clamping L bracket torque arm

Post by cassschr1 » Sep 22 2011 4:04pm

What bike is that. I'm making some now for a specialized FSR Pitch. Both sides, Clamping also 3/8ss POLISHED
Fitting to the drop outs was a b...h on the right side, there at the water jet place now.

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Re: Review my clamping L bracket torque arm

Post by John in CR » Sep 22 2011 4:28pm

Think about the radius from center and small size bolts used for the 6 bolts that attach brake discs, and those see more torque than our motors can create. As far as going off a drop, the original bike is what takes that, so as long as you don't weaken the bike with new holes in the wrong place or torquing down bolts in a manner that puts the alloy under stress, then you should be fine. The impact torque of a motor under throttle while in the air and spinning at a faster speed when you hit the ground is a different animal than I could answer though.

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Re: Review my clamping L bracket torque arm

Post by auraslip » Sep 22 2011 5:24pm

You could go with my method.
Not interested in torque plates. I've done it in the past, and I hate having to be nervous about it developing play during acceleration and regen cycles.
Besides, cutting thick metal precisely isn't fun. Because my method grips all of the axle flats, the torque is distributed over a much wider area so I can use 1/8" steel. Much easier to cut than what I'd feel comfortable with running 10kw (4" thick steel lol)
What bike is that. I'm making some now for a specialized FSR Pitch. Both sides, Clamping also 3/8ss POLISHED
Cool, always love to see some torque plates/arms. My bike is a $100 performance bike aluminum frame.
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auraslip   1.21 GW

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Re: Review my clamping L bracket torque arm

Post by auraslip » Sep 22 2011 5:29pm

Thanks John, those are all good points.
As far as going off a drop, the original bike is what takes that, so as long as you don't weaken the bike with new holes in the wrong place or torquing down bolts in a manner that puts the alloy under stress, then you should be fine.
This is my main worry. I don't want to take the time to file down the drop outs so that the axle will lay perfectly flat at the correct angle for the torque arm to mate with the top of the chain stay. But I guess I'll have to because the other (easier) option is resting the axle on the L bracket which is supported by only two m4 screws in the bikes 1/8" aluminum dropouts.
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Re: Review my clamping L bracket torque arm

Post by neptronix » Sep 22 2011 5:34pm

auraslip wrote:
You could go with my method.
Not interested in torque plates. I've done it in the past, and I hate having to be nervous about it developing play during acceleration and regen cycles.
Besides, cutting thick metal precisely isn't fun. Because my method grips all of the axle flats, the torque is distributed over a much wider area so I can use 1/8" steel. Much easier to cut than what I'd feel comfortable with running 10kw (4" thick steel lol)

I haven't had any problems with mine developing play but i also don't have regen. Point taken.
However the way that the axle flats were created, were by cutting them almost exactly and leaving just a little bit of extra metal, then hand-filing them down. It is really hard to get the wheel on the bike because it is such a tight clearance.

You do need the right tools for the job. I found a local speed shop that said they'd make me some more torque plates for the pike's peak bike for $40 a set including materials. Not bad. You may want to investigate paying a little $.

But best of luck to you in whichever way you go.
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Re: Review my clamping L bracket torque arm

Post by auraslip » Sep 22 2011 5:48pm

Thanks nep. This is my third set of custom torque arms/plates. I have TI drill bits, vises, and a hack saw. For $40 I'm going to get an angle grinder to make cutting quicker. Also need the appropriate tap and die kit. Can't decide if I should get HF $20 kit, or just a GOOD m4 tap. Or maybe both?

Also also, I need those little things that screw into holes and have a little point for you to tap the metal against so you can drill at an accurate place. I like buying nice tools :)

It's a pain, and kinda expensive, but I want to learn about this stuff anyways. Just wish I had some projects that wouldn't kill me if I do it wrong.

One thing you might try is docs new torque plates. Only $25+shipping a set and it looks fairly universal. Best part is that it's mounted to the frame with some sort of super epoxy instead of screws. Welcome to the future: where glue is stronger than steel.
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Re: Review my clamping L bracket torque arm

Post by amberwolf » Sep 22 2011 5:53pm

The HF kit sucks; the tap/die holder tool will break if any appreciable force is applied. :roll:

The taps themselves are questionable, but they work. I guess. I haven't broken one off yet.

The dies seem better, but they wont' cut into most of the metal rods I've tried, and definitely won't rethread any of the bolts I've needed to do.

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Re: Review my clamping L bracket torque arm

Post by auraslip » Sep 22 2011 11:58pm

Sorry to do this, but I'm turning this into a reference thread for myself.

Guide to screws http://store.curiousinventor.com/guides ... ing/Screws

Metalworking videos from MIT http://techtv.mit.edu/collections/ehs-v ... ine-shop-1

Best guide to hacksaws I could find http://www.google.com/url?sa=t&source=w ... 0w&cad=rja

http://en.wikipedia.org/wiki/Drill_and_tap_size_chart
Last edited by auraslip on Sep 23 2011 2:08am, edited 1 time in total.
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Re: Review my clamping L bracket torque arm

Post by neptronix » Sep 23 2011 12:14am

I'll be honest. I haven't lived in anything other than an apartment for about a decade now. So i don't have room to do this stuff on my own time. I am accustomed to paying someone a bit who has a shop and i watch and take notes. :?

Lots of success with the epoxy so far on the forums, i just have a hard time trusting the stuff. I will give it a year to see how it goes..
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Re: Review my clamping L bracket torque arm

Post by auraslip » Sep 23 2011 2:14am

ehhhhhhhh - not sure you need much room to work. Just a desk or table and room for a drill and saw. But yeah... it's about 100x harder than working with wood. Wood is so forgiving of my amateur skills. Metal isn't. And the tooling seems to be about 10x as much - rich mans hobby for sure...

I'm thinking that it'd be better to invest in a nice hacksaw frame and good blades over a cheap angle grinder. The cool thing about this torque arm is that it doesn't require very many precise cuts. (or very many cuts at all) In fact, I could probably get away with just using stock metal from the store and only have to cut it to length.
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Re: Review my clamping L bracket torque arm

Post by neptronix » Sep 23 2011 2:30am

angle grinder and various bench mounted and floor mounted tools were used to create my plates. They sure as hell aren't quiet. But definitely sped up the process, lol.
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Re: Review my clamping L bracket torque arm

Post by Spacey » Sep 23 2011 3:23am

I've had my Araldited torque arms from DocBass for 2 days now and they do not budge! The axle does move a tiny bit but that is due to the pitiful straight edge on the HS3540 motors.....and the fit was so damn tight I had to beat the motor on with a hammer to get it into the torque arm.

The Araldite is stupid strong and took 2 hours to do both torque arms......regen here we come. For your motor where there is no back and fourth from the acceleration and regen it would work so well.
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Re: Review my clamping L bracket torque arm

Post by dogman dan » Sep 23 2011 6:02am

Look for some 1/4 thick angle for your design. My first version of my dirtbike pinchers was 1/8 angle, and it just bent like hell under the pressure of tiny 10mm bolts. The fatter second version has held up nicely to up to 3000w with no problems at all.

Pic for reference for those that haven't seen it yet. Simple pinch dropout for mongoose blackcomb, brake side. Still using the nut on the derailur side.
CIMG0182.JPG

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auraslip   1.21 GW

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Re: Review my clamping L bracket torque arm

Post by auraslip » Sep 23 2011 9:33am

thanks for posting the picture again - it's pretty much the thing that got me thinking about L brackets

Speaking of, i'm glad to know that 1/8" deformed for you. Well, I didn't think it would with it clamping on both sides, but I'm glad you said something. I'll have to use 1/4" now. Worry free and overkill and torque are all things I like to hear in a sentence.
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auraslip   1.21 GW

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Re: Review my clamping L bracket torque arm

Post by auraslip » Sep 24 2011 1:20am

God. Angle grinders are dangerous.

I wore glove and goggles, but forget the ear pieces. Feels like cotton balls. Nice little hum. Stupid thing is I have shooting headphones a drummer left in my tool box.

Also - iron fillings all over my work room. Needs to be done outside. Sparks everywhere too. Could start a fire it's so dry outside.

On the upside, it turns an hour worth of work with a hacksaw into 15 minutes. Probably could do a lot better once I get my speeds and feeds right too.

Just gotta make sure I don't lose a finger first!
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Re: Review my clamping L bracket torque arm

Post by amberwolf » Sep 24 2011 4:51am

If you have a bench, two hose clamps (bolted down with overlapping fender washers or the like) or large U-bolts to hold the angle grinder to it at the desired angle, with its' debris outlet side pointing down into a metal bin of some type (trashcan, etc), will greatly reduce problems using one to shape parts.

It lets you maneuver the part, instade of the grinder, so it is usually easier as the part is almost always smaller and lighter. You just have to make sure ou ahve good hold of it. If it is a small part, use large vise-grips to hold it very securely, and keep both hands on the grips.

If you're using it on a frame or somethng, it's probably easier to clamp the frame down and maneuver the grinder, but there's not much way to control the debris stream, unless your grinder can be fitted with a recovery bag or vacuum hose (like a number of bench-mounted cutoff saws have). If you can use a vacuum hose, and have a shop vac, you can put the hose at the debris outlet of the grinder, turn on the shop vac, and it will help control the stream and cool it off at the same time as it sucks lots of air past it as it goes down the hose. Big pieces will still melt plastic hose, so beware. ;)

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Re: Review my clamping L bracket torque arm

Post by dogman dan » Sep 24 2011 6:41am

It must be tough, not having a third acre to sprawl out on with places to weld, grind, etc. Any kind of vise to hold the steel will do wonders for making it safer. Someting ghetto, like a vise grips attached to a 2x4 somehow, then a foot on the 2x4 will help safety a lot.

When shaping, like deburring, as AW said, secure the tool, so you can hold the workpiece with two gloved hands. Those grinder get even more safetly last, when you take off the guard, so you put a 6" disk on there. :twisted: :lol:

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Re: Review my clamping L bracket torque arm

Post by auraslip » Sep 29 2011 1:00am

If you guys get me killed doing something you suggested, you don't get any of my ebike stuff

:lol:

The project is coming along.... sloppy and ugly on account of my lack of know how and continual changing of plans. I wish I had some less expensive hobbies and easier hobbies to practice this sort of stuff on. Nothing like having a $1.5k ebike look mad max cause a torque arm...
Image
Almost done though!

I lucked out and found a four foot 1/8th L bracket for only $3. Not strong enough for the torque arm or the plates, so I doubled it up. If I could do it again, I'd use 1/4" (or more). If I could do it again, I would. But I'm busy with school, so this will have to work.
Image
Did my first tap ever tonight! Not bad. I used 1/4" grade 8 bolts coarse thread (because those are stronger?) I'm concerned they might not be strong enough, and might strip the bottom 1/4" plate. I bought lock nuts just in case.
The cool thing about this design is that the top part is permanently fixed, so I just need to remove the four bolts holding on both bottom plates to remove the wheel. That's just one tool I have to carry now! (unless I keep the lock nuts)
Image
Had some trouble lining up the plates to drill. Lil jig.
Image
I was freaking out about paying $15 for a heinman taps to screw into the original rack eyelets. Then I realized they aren't blind and I could just thread a bolt on there and hit the front with a hammer to line up the hole.

Next up is painting the scratched up metal with rustolem, wrapping the chainstays with tire tube, and putting the finishing touches on everything.
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Re: Review my clamping L bracket torque arm

Post by LI-ghtcycle » Sep 29 2011 2:03am

Be careful with that U-Bolt, it can cause you trouble on the chain stay since it won't conform to the shape of it very well, might consider two hose clamps instead as they will form a better more even pressure all around the tubing where as the U-Bolt will tend to only contact in two or three places, and if you over-tighten it, it could cause serious damage to the aluminum.
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Re: Review my clamping L bracket torque arm

Post by dogman dan » Sep 29 2011 6:21am

Looks a bit hand made with a grinder, but I like that style myself. I was about to say you need to bolt the angle to the frame, but then saw you did that, just don't show the final pic. Looks good to me. I don't think the U bolt will get as much pressure with the single bolt on the L bracket helping. I'd go ahead and put a nut on the bottom, just since you can. It'll back up your threads in the plate so they won't want to strip.

Later on, maybe make a V2 design, where the entire top piece is cut from a single piece of angle? Or maybe redesign the little angle piece so it can also be u bolted to the seat stay?

On the other hand, it may be perfect right now.

I assume the dropouts are now 14 mm? hence the funny position of the axle? No cracks?

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Re: Review my clamping L bracket torque arm

Post by auraslip » Sep 30 2011 6:29pm

Image
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Re: Review my clamping L bracket torque arm

Post by auraslip » Sep 30 2011 7:04pm

All done! Lightcycle was right about the u-bolts. Now I just need to trim down the hose clamps so I don't cut myself on them. I think one per side will be enough. Does anyone wanna guess how much power this should be good for? I'm hoping at least 8kw *fingers crossed*

Just need to paint it, and then I'll be done!

Image

Image

Image

So, don't use an angle grinder to grind down the axle! Especially if you don't know how quickly it eats through aluminum! I was forced to do this to make them balanced! I'm either gonna convert to single speed, or epoxy/bolt that hanger to the frame.
Last edited by auraslip on Nov 23 2011 7:26pm, edited 1 time in total.
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