How to bend 4mm aluminium plate?

[Rudderman]

I have a sheet of 4mm aluminium plate that I want to bend so it will fit over the transom so the outboard can clamp to it. Any ideas how to do it?

 

[Capt. T]

Re: How to bend 4mm aluminium plate?

Aluminum that thick is very difficult to bend w/o heating and even then it is likely to crack.<br /><br />If you are set on trying to bend it, you could try bending it 90 deg. and then cutting it so you have one piece that looks like an upsidedown 'L'<br /><br />The long leg of the 'L' would go down either side of the transom and the short leg across the thickness of the transom. Next have the second piece welded so the final weldment looks like an upsidedown 'U' which will side down over the top of your transom.<br /><br />IMHO: you would be better off to have both long legs welded and forget bending. I think you've got less than a 50/50 chance of making a successful bend.

 

[BillP]

Re: How to bend 4mm aluminium plate?

How difficult depends on what grade...soft aluminum will bend easy and marine grade not so easy. Take it to a metal fabricator and have him bend it correctly...it will take him about a minute to do it manually.

 

[Rudderman]

Re: How to bend 4mm aluminium plate?

Thanks guys, looks like I will just try to get someone with the correct equipment to do it for me.

 

[Rudderman]

Re: How to bend 4mm aluminium plate?

Its 5083 aluminium.<br />Maybe 4mm is overkill anyway...what do u guys use on your transom?<br />The only reason I want to bend it is to protect the top surface of the transom (the edge of marine plywood)

 

[Winger Ed.]

Re: How to bend 4mm aluminium plate?

Originally posted by Rudderman:<br /> Maybe 4mm is overkill anyway...what do u guys use on your transom?

I don't know about that metric stuff, but I see them usually running about .060" to a little less than 1/16th of a inch or so if they're not required to add any support to the transom.<br /><br />The Aluminum strips that do have to provide some support to keep the transom form flexing under engine torque that I've seen and used, are commonly a piece of Alum. angle stock 2" x 3" on a side and about 1/8th inch or maybe a little thicker.<br /><br />Ed.

 

[Rudderman]

Re: How to bend 4mm aluminium plate?

4mm = 0.160 inches<br />I tried bending it and you were right, it was very brittle and cracked. Maybe I'll go for stainless instead.

 

[Chris1956]

Re: How to bend 4mm aluminium plate?

Rudderman, why don't you use standard aluminum angle iron? Get some wide enough to cover the top of the transom, and put the bend on the inside, so it will not interfere with the mounting of the outboard. Secure with pop rivets or screws. Home Depot and hardware stores carry the stuff!

 

[Moody Blue]

Re: How to bend 4mm aluminium plate?

Don't waste your time trying to bend that stuff. As mentioned it WILL crack and break especially if you want a tight bend. If it was 3003 alloy you might get away with it if you had a 30ton brake press but the material is quite soft so it wouldn't give you any strength. To reinforce my transon (overpowered from 25HP to 40HP) I added a full width piece of 3/4" marine ply and capped this and the original transom with a 3" x 2" x 1/4" 6061 alloy extruded aluminum angle (short leg over the top). The top two bolts from the motor bolt through everything and the bottom two bolts only through the original transom and new ply. This thing is absolutley rock solid and doesn't move at all, even when pulling a tube. Maybe a little overkill but I am confident I won't twist off the back of the boat. The aluminum angle should be available at any metal supply warehouse or distributor. I got mine at a place called Metal Supermarkets.

 

[Rudderman]

Re: How to bend 4mm aluminium plate?

Thanks for the advice, I got a stainless steel plate made up. Only problem is that stainless steel is so hard that the little ridges on the motor bracket don't make an imprint in it at all on the outside. I think I'll just crank the handles down hard and stick a couple of bolts through the clamps/transom/plate for good measure.

 

[petrolhead]

Re: How to bend 4mm aluminium plate?

Dave, add a piece of ply to the outside, the ridges/teeth on the transom bracket will grip it much better than the aluminium.