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Cutting steel plate


Boro

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Im in the market for something to cut steel plate, mainly 3 and 5mm thick and lots of curves etc, plasma would be great but my budget is limited to about £200 so cant see myself getting a decent plasma for that :lol: what are peoples thoughts on using a jigsaw? i had a quick look and came across these http://www.powertoolsuk.co.uk/webcat/detai...BCE&ID=2287 which are within budget, have a 10mm cutting capacity for steel (so should be fine with 5mm plate), will cut at a fairly slow speed (sure i read somewhere online 500rpm) and are covered with a 3 year guarantee, what are peoples thoughts on these please?

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What sort of path length are we talking about here? I think you'll be throwing a jigsaw at the nearest wall pretty quick with 5mm plate. You could do it, if its just to get a small job done, but...

I hate to say it, but you're really into plasma territory.

Can you borrow one, or oxy/acet, or get someone else to cut it out for you? How much of it is there? One off or repeat?

Does it have to be 5mm? You could try a nibbler if you can use thinner stuff. Whats it for?

Cheers, Al.

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Path length approx 150mm per cut, a full set of mounts would end up being about 10 or so cuts, cant borrow a plasma and oxy well its not that neat or accurate so you would need to cut oversize which leaves makes more time to finish the cuts by hand and its the cost of setting up, bottle hire and fills etc, i certainly cant get the first lot cut by someone else as i will be cutting to card templates then adjusting to fit initially, its to make mounting brackets up for myself but im considering retaining patterns and making some jigs so i can make them to sell in future, i would rather stick with 5mm plate as i feel anything less could end up being too flimsy, i take it that your suggesting cutting with a jigsaw plate of this thickness will be slow and tedious? what would a half decent entry level plasma capable of neatly cutting 5mm plate cost? air not being an issue as iirc my compressor is 4hp, 18cfm with a 150 or 200 litre tank i cant remember which

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If you're looking at even small scale production, I think plasma or gas is inevitable. In light of that, why not get it set up for the first one and save yourself the agro?

Its only short cuts, so I'll backtrack slightly and say you could do it with a jigsaw, but its a waste of time and investment.

I don't know anything about budget plasmas, sorry, but just take their cut-depth claims with a pinch of salt if you want the outcome to be fairly neat. I agree about the material thickness, don't skimp on it - if anything, go thicker.

Al.

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...and oxy well its not that neat or accurate so you would need to cut oversize which leaves makes more time to finish the cuts by hand...

It can be very accurate. I had a friend who cut circles cleaner then a hole saw and would cut between two lines a millimeter apart and leave both scribe lines intact.

I have used jigsaw blades to cut 60x8mm steel angle. About one blade per cut. Took ages. After I started the third cut I gave up and reverted to a hacksaw, it was quicker and quieter.

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Les what do you call a plasma blade, those very thin discs? got some of those already although cant remember if i have ever used them for thicker steel and i have never tried the really thin ones as im not sure i trust them not to explode on me :ph34r: it seems to get a half decent non chinese plasma cutter that will do what i want would be about £600 so thats out for the moment, maybe one day!

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Yes, plasma cutting discs are the really thin ones (1mm or less) - they are ok, just remember to wear goggles and preferrably use the guard on the grinder too and they will be fine, probably quicker than a jigsaw and a dam site cheaper than the blades too.

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When I did my axle swap using mostly 3mm box and plate, a fair but of 6mm and some small bits up to 8mm, I used the following (in order of most use):

14" chop saw with normal 'grinder' type cutting disc

9" normal cutting discs in grinder

9" and 4.5" plasma blades in grinders

some small bits with the jigsaw

Total cost of consumables was in the region of £40.

I also got some of the 3mm and 6mm plate guillotined into 4" wide strips by a local fabricator - that helped a huge amount

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Oxy-cet depends on the user. You can get a very clean and precise cut with oxy acetylene, but it comes with experience.

Oxy-propane os only good for chopping up scrap, can't profile burn with that.

Plasma cutter - I got one of those cheap chinese jobbies, Berlan make I think and it's already paid for itself with fabrication. It will cut cleanly upto 6mm, and reasonably upto 8mm, anything over 10mm is rough and needs a bit more dressing. One thing I would say is that it seems to go through tips fairly quickly, and the shrouds tend to get broken as the torch is being kicked about the workshop floor. So if you do get one buy a bag of tips and shrouds at the same time, as delivery from overseas tends to take about a week.

The bonus with the plasma cutter (which can really make a difference) is that you get no distortion of thinner metals due to heat. When cutting with grinders the heat can often buckle thinner metals.

I think you'd be suprised at even the cheapy chinese plasma cutters. I wouldn't think they'd be up to daily industrial work, but certainly good for light duty fabbing.

We also use them plasma discs quite a bit. They're spot on for cutting straight lines, but of course they're not much use for curves, and definately not for grinding. Never had one shatter.

For heavier plate, upto 12mm, we use an Evolution circular saw. Again no distortion as there's little heat, and a perfect clean cut, looks like it's been milled. The downside is, just like a wood cutting saw, that it's only good for long straight cuts.

evosaw.jpg

On this job we needed the plate to be 20mm thick. We didn't have any plate that big so we cut two shapes at 10mm (see the other one laid on the sheet under the rules) and welded them together.

As an aside, notice the two large holes cut out of this 10mm sheet? They were cut with oxy-cet. Although it may not be clear in this picture, I can assure you the cut is very clean!

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One thing I would say is that it seems to go through tips fairly quickly...

Probably a combination of low budget materials and moisture in your airlines. If you care enough to do anything about it, try getting drier air.

Al.

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Not read good things about berlan, i read that all units had been taken off ebay as it was found that berlan had forged the ce certificate or something, doesnt exactly inspire confidence in them :o

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Our air supply is dry enough to spray with direct, the compressor is inter and after cooled which does a good enough job of drying it out, so probably down to carp tips as you say.

I've not heard good things about Berlan gear either, I only bought it to do a one-off job, and bought it because it was cheap.

I believe the problem with them is that there's a serious risk of the torch or earth connector going live when in use. That means if anyone was to touch this coupling whilst it was cutting they would get a beefy electrical shock.

That said, it's been a good bit of kit and on a few jobs I've wondered how we managed without it.

It's certainly made life easier. Not just for fabrication, but for some fiddly jobs too. A recent one was cutting a bracket off the underside of a trailer, difficult to access with a grinder, high risk of damage to nearby airpipes and wiring by using the gas. Using a hand saw would have been a long and tedious job. Whipped the bracket off in a few seconds and without having to heat the metal with the gas torch first.

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I was cutting 5mm the other day with a 1mm disc on my 4 1/2" grinder. Went through it a treat, and a damn site quicker than a jigsaw. A bit of practice will give you more confidence in these thin discs, they're surprisingly forgiving.

If thin plate is distorting with heat you may be giving it too much welly :rolleyes:

As previously pointed out the grinder's only good for straight cuts. I did have to resort to the jigsaw when I made my gas tank cradle. That was 3mm plate and took ages to cut.

post-7124-1245186308_thumb.jpg post-7124-1245186316_thumb.jpg

Oh how I want a plasma...

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  • 1 month later...
ts420.jpg

+1 :lol:

But thats a diamond stone cutting disk :P

I swear by my stihl saw!, It's older than me, Its about 30 years old! :blink: and is still on its original piston and ring :P and goes through scrap alluminium panels like butter

Prefer to use my stihl saw over a 4.5" or 9" grinder :o

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For small brackets on a limited budget, just get a bundle of plasma grinder discs - cut the rough shape out & then use a grinding wheel or flap wheel to finish. If you have a fair bit to do, try chatting up an engineering company with a plasma, water jet or laser cutter and offer cash in hand.

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theres a few fab shops around now with plasma cutters, its long-term cheaper than paying for profilers to do it all for them. Failing that, i use Malcolm High at http://www.modelengineerslaser.co.uk/ to do 80% of mine. Very good prices, but you have to wait about 3 weeks as he fits them into other customers 'waste' materials, so you have to wait for enough of the right thickness material to pass through!

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