taking dents out of Birmabrights

van Ginneke

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Is it possible to take dents out of Birmabright mudguards? The material of the ones I have feels like it's hardened over time (?) or perhaps they are always like that?
I have not tried anything -yet- but I would like to know if there are any do's & don'ts when trying to take dents out of them.
I thought of making a solid wooden form that fits inside the guard of about 30cm long and as wide as the inside, (one for the front & one for the rear guard) and then using a wooden or nylon hammer on the outside to get dents out, any comments?
Or should I do it the other way round? e.g. A wooden form where the guard goes in and hammer from the inside of the guard?
One of the guards also has a 'kink' in the beaded edge, anyone any (Birma)bright ideas on taking that out? best regards, Vincent
 

timetraveller

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I'm no panel beater so there might be other who will reply to this who are more qualified than I am to give you the correct information on how to do this but I have done this successfully. If you search through your local tools catalogue, or perhaps ask among your friends,for a cheap panel beating set then you will find a kit of parts which consists of a series of solid steel dollies with varying radii and various hammers. It is possible to find part of the surface of one of the dollies which has just the correct radius to fit inside the mudguard. Hold the dolly inside the mudguard and with a hammer gently tap around the dent. I found that a lot of gentle taps was better than a few strong ones. It is possible to both shrink and stretch the aluminium and with a little patience, and not too much time, then you can get the dent to just about disappear totally. There will probably be a little bruising on the outside of the mudguard and I used a polishing mop to get rid of this. I might have been lucky but it was actually easier than I thought that it would be and as far as I could tell the trick is to use the correct curved dolly. As for the kink in he beaded edge then I suspect that that might be beyond my capabilies but once you have done the main part of the mudguard then it might be possible to see how to attack the beaded edge. Good luck.
 

b'knighted

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I'm also not a panel beater (so there might be other who will reply to this who are more qualified than I am to give you the correct information on how to do this) but sheet metal workers always told me that to shrink aluminium a hide mallet should be used as a hammer would thin and stretch the material.
 

davidd

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I suspect the mudguard is has not hardened too much to fix it. I would make a wooden mallet or shape on that has a small sphere much smaller than the curve of the guard if the crease is sharp, larger sphere if there is just a general deformation. Buy a bag of sand and lay a shop cloth on the bag (shape the area by pounding it with your fist) and beat on the underside of the mudguard until the dent is generally gone. Take a small fine file and run it over the other side and you will see high spots and low spots. Keep working the low spots out (you may have to reshape the mallet end smaller or sand down the end of a wooden stick and use it like a punch). If you end up with a few high spots on the outside, use a flat hammer on the outside using the hammer end as a dolly on the inside. Just work away until you are happy. Sand the outside with fine to very fine sandpaper such as 800 and go up to 1500 if you can, then buff and polish.

Just take your time and work gently until you can see how much metal you are moving as you work.

I do not think that you can easily do anything about the lip except to straighten everything and it should not be that prominent. There are many specialized tools, but what I have described should do the trick.

David
 

van Ginneke

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Thanks, B'knighted & David, I will follow your advices and use something I know I got,...patience!
Some time ago I bought (out of curiosity) a 'special' panel beating hammer with a surface that looks like having 'teeth' like a rough file but in a circle. The hammer head is bonded to the rest of the hammer by rubber and when you hit the metal it makes a very small 'twisting' move.
Because of this twisting & the teeth the metal does not stretch -I was told- and it works on metal but I dont trust it on alloy as you have to hit rather hard in order to get this twisting action. On sheet metal I did get some nasty dents out but the teeth make marks on it.
 

davidd

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I have seen those hammers, but I have never tried one. I have a hand operated shrinker, but it is best for edges and the metal will need to be finished to rid it of the teeth marks. In general, you stretch and shrink with the same hammer as you are working with. You hit into a void or a bag, to stretch. By doing so the metal tucks or puckers around the stretch and you hit the tucks with the same hammer on a hard surface to thicken the metal. Here is a good demonstration:

http://www.youtube.com/watch?v=7-cIDfe0FfE

David
 

nobby

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VOC Member
Hi Vincent,
I have some birmabright leftovers from racing, all are cracked ofcourse. If you want to practise first on those blades you can have them.
 

Tug Wilson

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Non-VOC Member
Take it to a "wheeler" someone who uses a wheel to form curves. My tank (in 3 bits!) and Birmabrites were done locally here in the sunny south by a guy who makes new parts for Tiger Moths etc.
 
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