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Old 10-02-2018, 07:21 PM
Mucci Mucci is offline
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Default Having trouble with hemmed edge on motorcycle fender

Hey guys. I just got a motor for my bead roller along with a tipping die. I'm trying to do a hemmed edge on an aluminum motorcycle fender and am having trouble.

I've gotten decent at forming the basic fender with a combo of malet/bag, e-wheel, and plannishing hammer. The curve will be right where I want it, then I go and mess it all up by trying to do the hemmed edge.

Here's my hemmed edge process right now:

Make 1 - 2 passes on the bead roller with the tipping dies, pulling up to fold the material over. I can get it to about 75 degrees this way.

This is what I'm using:





This is the fender I'm trying to make:



After I get it to 75 degrees that 1/2" of folded metal gets very wavy around the front and rear ends of the fender. Too much to fit in my shrinker. Trying to hammer the edge over from here is what's messing things up. When I do get it folded over the curvature of the edge is usually distorted and uneven. There's now a point to the tip of the fender where the buckle was even though the bead roller pass was smooth and consistent.

I've also tried hammering it over to 140 degrees or so then running the edge through the planishing hammer to squash it down. This works great on the long edges, but in the bunched up ends the metal gets mangled and will imprint the hem into the top surface like this:




What is the correct way to hem a tight radius like a motorcycle fender? Should I be trying to shrink that 1/2" edge a bunch BEFORE bead rolling it?? Is there a way to shrink it after bead rolling to a 90?

I've seen that these hem edge die sets exists. Would these work to hem such a tight radius, especially when the material is buckled?

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Last edited by Mucci; 10-02-2018 at 07:39 PM.
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Old 10-03-2018, 12:10 AM
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MP&C MP&C is offline
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In making the first "pass" with the tipping wheel, I like to add some pressure on the wheel and don't tip it yet, does a good job of marking the bend line and tends to keep me on the same line on the repeat passes by having a good line to follow. Next thought is when using that step die on the bottom as your depth gauge, you may notice the edge drags a bit on the inside corners. Try replacing it with a beading die, still have an edge to use for the depth stop but the rounded edge makes things glide a bit better on inside corners.

I've also done some tips where the final was done by hand. I'd suggest to focus on the high spots (tucks, ruffles, whatever you'd care to call them) on those tight ends to try and prevent the peaks from forming. With a bit of finesse you should be able to get it to shrink back into itself. If it doesn't want to play nice, you can always use a Lancaster or kick shrinker to tighten it up a bit before the final folding takes place
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Old 10-03-2018, 02:31 AM
skintkarter skintkarter is offline
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Hi Dave, there are far more learned folk on here than I, but I would suggest that you are perhaps being too ambitious with the 1/2" return.

Think about where that 1/2" has to go as you lift it up around the radius - a whole bunch of shrinking going on.

If you want a straight hem as opposed to a wired edge, then I would do some testing on some scrap with say a 1/4" return - far easier to move around. And I'd be annealing it probably a couple of times through the process.

Also I'm not sure that I would be using the bead roller for this job unless you are really proficient in running the bead roller. I built a really whizzy powered thing (Tom Verity style) but whilst I've done a bunch of joggling and other stuff, I've still not got the hang of tipping without the ends getting away on me.

If this were my job, I'd be trying to do the first piece of scrap by hand with some modified vice grips, or a crescent to tip the edge to getting on for 90 degrees, before tidying up with a hammer and dolly to help with the shrink - some smacks down on the edge on a flat stake will help the shrink. Then I'd be trying to close it down (more shrinking) again on the flat stake dolly.

A wired edge is a whole 'nother thing. Peter Tomassini has some good info on here regarding wiring an edge.

However I'm just a nipper in all of this stuff...
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Old 10-03-2018, 06:31 AM
Peter Tommasini Peter Tommasini is offline
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Dave you have far too much metal on the turned edge (flange). The formula is 3 time the thickness of the wire + the thickness of the metal ,so in your case if you are using 1mm steel and the wire was 3mm .... the flange would be about 10 mm 3x3=9+1
now the same goes if you using 1.2 metal and 4mm wire that would be 13.2 4x3=12+1.2

turn the flange by hand using a pair of pliers, or brake the edge on a bead roller then finish turning by hand, once the wire seats on the turned edge clamp it with vice grips, so it can not move, put a dolly under the edge and by using the wire as a dolly start turning the edge over little by little, once the edge is over use a pair of vice grips and close the edge right up.
Peter
PS if the wire is the proper length it will shrink it self around tight corners, you just need to hit it right and use a rounded face hammer
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Last edited by Peter Tommasini; 10-03-2018 at 06:36 AM.
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Old 10-03-2018, 05:15 PM
carl 180 carl 180 is offline
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Hi dave i would just half the amount of material to be turnned over on the radius.if you take a look at the back off a door or boot skin you will see what i mean.
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Old 10-03-2018, 05:50 PM
Mucci Mucci is offline
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Here's my attempt with 1/4" fold instead. Much easier, but I'm still having trouble keeping the smooth symmetrical curve.



You can see it's not very symmetrical anymore even though my pass on the bead roller looked good. That curve gets away from me during the hammering over process. After tipping it 90 on the beader i've been holding the fender upside down on an 18" bag and folding the edge over with a hammer & slapper combo. The edge get's inconsistent when parts of it fold over easier than others; mainly where the tucks are.

Good tip on the annealing. I think next time I'll try annealing again before tipping and maybe even running it through the Lancaster to try and eat up some material.

Would there be any benefit to try folding less than 1/4"? I'm using .063" 3003.
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Old 10-03-2018, 06:56 PM
BTromblay BTromblay is offline
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Hi,

I have had great success, with the following technique.
1, Tip the edge 75deg with your bead roller.
2, Do not anneal the part. By annealing, you can anneal a much larger area than needed and make a dead soft fender.
3, Heat the flange area only-ish to 300°F and form it over the rest of the way, while hot. The heat will allow the material to shrink with little effort. If it cools, re-heat and only form while hot, with a rawhide or wood mallet. To gauge the temp, I heat until I can't touch it any more. I coat the surface with black magic marker. If I burn off the marker, I'm at 650°F and at the anneal temp, to hot.

While forming hot, you can form a long flange length, much easier. Give it a try, good luck with burning your fingers

Bill
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Old 10-03-2018, 07:07 PM
Mucci Mucci is offline
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I''l give that a try. Thanks Bill
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Old 10-03-2018, 09:45 PM
Mucci Mucci is offline
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Alright, this take was the best thus far (I think that's around 6 or 7 failed attempts now).

I folded over a little less than 1/4" and tried the light heat on the edges trick while folding it over with a mallet. That seemed to make it easier. I also kept changing the location of the hammer blows so as to work the entire edge down gradually. This also helped. Before I was more so trying to "steam roll" around the edge and I think that caused a lot of my problems.






Now my question is how should I finish this? My end goal is a lightly brushed finish. Do I just use a DA to smooth out these lines from the wheel?

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Old 10-04-2018, 03:38 AM
tom walker tom walker is offline
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Very nice result! I also learned something in the process. Thanx for posting.
Tom
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