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Sump chopping
Benzine - 30/4/09 at 02:37 PM

I want to take about an inch off my sump, so far i've had it flat on the worktop and scribed a straight line round the whole thing. How is the best way to go about cutting it? It's aluminium btw, I read something about it being a bad idea to angle grind Al before? Jigsaw? All by hand with a hacksaw?

flak monkey - 30/4/09 at 02:39 PM

1mm thick angry grinder discs from wickes or screwfix. They are suitable for aluminium so no problems

David

Benzine - 30/4/09 at 02:42 PM

Ossum, maybe I could rig up a jig to hold the grinder in place so I can slide it around the sump to keep it straight and flat...

speedyxjs - 30/4/09 at 02:45 PM

If its ali, why not just do it by hacksaw?
I would be a little worried about the heat caused by the angry grinder but im not experienced in ali so may be wrong

flak monkey - 30/4/09 at 02:45 PM

Just bolt the sump down, or clamp in a work bench and run the grinder round it. Its not *that* difficult to cut straight, just take your time

DaveFJ - 30/4/09 at 03:31 PM

have heard that is a bad idea to use grinder disks for both steel and ally... if thats true then i would say use a fresh disk just for ally....

alternatively, i would use a jigsaw and ally blade

[Edited on 30-4-09 by DaveFJ]

MikeRJ - 30/4/09 at 04:01 PM

quote:
Originally posted by flak monkey
1mm thick angry grinder discs from wickes or screwfix. They are suitable for aluminium so no problems

David


Standard ferrous metal cutting disks (whether 1mm or 3mm) should not be used for aluminium unless the manufacturer states it's suitable.

You can buy cutting disks especially for aluminium and universal ones suitable for ferrous and non-ferrous metals, but note that aluminium dust is quite toxic if inhaled, and can cause some nasty diseases. It also forms thermite if mixed with ferrous dust...

nib1980 - 30/4/09 at 04:17 PM

don't use a grinding disc for both steel and ali, you end up with aluminum iron oxide in the disc also know as thermite, gets hot and explodes!!!

many documented cases.

ali on it's own yes

steel on it's own yes

both on same disc equals dead

please be careful


http://en.wikipedia.org/wiki/Thermite






[Edited on 30/4/09 by nib1980]

flak monkey - 30/4/09 at 04:58 PM

You'll wear a disc out pretty quick cutting ali anyway. Most of the 1mm discs are universal and are suitable for ferrous and non ferrous.

I have cut both steel and ali with the same disc and I am still alive. You need quite a lot of dust laying about to cause a major problem. There wont be enough residual material in the disc for anything to happen.

David

jacko - 30/4/09 at 05:22 PM

Just use a jigsaw and put oil on the alloy when cutting, to start the cut drill a line of 3mm holes to get the blade though

nib1980 - 30/4/09 at 05:28 PM

no problem but i'm not taking the risk

http://www.hanford.gov/rl/?page=542&parent=506

MautoK - 30/4/09 at 08:17 PM

I used a hacksaw, new 32 TPI blade, and plenty of time....don't rush it!

DaveFJ - 1/5/09 at 08:14 AM

quote:
Originally posted by nib1980
no problem but i'm not taking the risk

http://www.hanford.gov/rl/?page=542&parent=506


damn thats scary reading!!

trogdor - 1/5/09 at 09:25 AM

I must admit when we did a thermite demo at college it was pretty impressive!

The lumps of molten iron formed burned through three heat proof mats.

However I thought for a thermite reaction you needed a certain type of iron oxide, one with a different oxidation state to the common iron oxide Iron (III) that is rust, Iron (IV) is it?

[Edited on 1/5/09 by trogdor]