I need to cut a V shaped notch in some aluminium plate, it needs to be approx 4mm deep and nearly 1m long, with 45 degree side angles.....i dont have a mill, any suggestions as to how to achieve this?

Buy a router from B&Q and hope?

If it's to allow the sheet to be folded then a regular angle grinder works surprisingly well. It won't give you 45° angles but when the sheet is folded and tacked the groove won't be visible.

Worked for me anyway

I agree with najw, I've had good results with using a grinder to groove plate that was too thick to fold otherwise. I don't have a sheet metal folder so i end up doing this quite a lot.

If this is for that great big chunk of bash plate you're making, I suspect you don't want to take a grinder to it. You could make up some guides for a pillar drill and use that as a mill, or as fridge says experiment with a router and guide plates - it could be fun!

Cheap router bits work surprisingly well on Ali!

As has already been said... if it is just for folding then I would use a grinder and cut a groove which I think would actually work better than a perfect 45 degree v groove? (I stand to be corrected ). Again if it is for folding why not seek out a local engineering type place who would do it in seconds on a press brake for nothing or a few beer tokens?

It is for the big bash plate, at the cost that is it...im not gonna risk bodging it!!!

I am getting a local place to do the big bends, but there are 2 end flanges that they cant/wont do because its so close to the edge of the material, so it will need notching, annealing bending and then post treating to re-harden it....i think i might try the router approach, gotta be worth a giggle as holding this thing under a pillar drill to use it as a mill, although a good idea would be tricky to say the least!

how thick is it Smo? have you got a plasma cutter or access to one?

Its 8mm, 6082-T6...sadly not got a plasma, or a tig for the next stage

A punch nibbler?? Or is the ali too thick?

Its 8mm thick as stated earlier so yes, just a bit, i also dont want to cut through it, just "score it" to ease bending.

I'd go with the cheap router route myself with a V shaped cutter. Set the speed slow and go easy with a few passes until you get the depth you need.
I wouldn't use a grinder on aluminium as the bits of ali will get trapped in the disc and if it expands due to the heat then it can shatter the disc.

Another way is to use an inverted dovetail milling cutter in a router ............. if you use a fence to keep a straight line and a little paraffin it cuts just fine. You can get small dovetails from RS Comps ............IIRC those cutters are Ok to 30K rpm ............


Like here .....http://uk.rs-online.com/web/search/searchB...54552&Nty=1


the mini mills work good on ali....http://uk.rs-online.com/web/search/searchB...p;x=25&y=12


But don't tell the H&S man that I suggested it............

I would not want to score or notch it as that will create a stress riser and it will crack at some point in the future. It would probably crack as you tried to bend it.

You need to anneal it and plan for a bend with no smaller than 8mm radius.

Steve

If it's just to bend it then find a local fab shop with a press brake,mark on the lines and ask them to fold it,To bend a steering guard will take about 15 mins to set machine and do job so won't cost a lot,
I do a lot of one off's for people just walking in and don't charge much,
Carl.

The problem with this is there is very little material between the top/bottom edges and the bends, its my fault as i designed it (i dont do sheet metal) and should have allowed more and then cut it back.

Whatever happens, i cant stuff it up, the plate and cutting cost a small fortune.

There are some kind people on the case, but if all else fails i shall take up the suggestions in here...where there is a will theres a way!!

[quote name='smo' date='Apr 9 2008, 06:31 PM' post='253248']
The problem with this is there is very little material between the top/bottom edges and the bends, its my fault as i designed it (i dont do sheet metal) and should have allowed more and then cut it back.

How mutch material is left on the edges,If you have about 15/20 mm left then you can fold it in a smaller bottom V tool,
Carl.

I suppose at worst you can cut off those bits and weld them back on at the angle you need.