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Sheet metal saw.

Is there a secret to stop it bending?

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Bo'sun31/08/2021 17:03:25
517 forum posts
2 photos

Hi All,

I need to cut some 0.9mm mild steel sheet. I don't have access to a guillotine and don't fancy using tin snips, especially as I want to keep it flat.

I've borrowed a "Shetack" sheet metal saw that takes a 12" blade. However, anything past half a turn of tension on the wing nut, causes the saw plate to bend.

Is there a secret to tensioning the blade, or do I need a special blade? I'm currently using it with an "Eclipse Plus 30 flexible bi-metallic HSS" 24tpi blade.

Nigel Graham 231/08/2021 17:05:44
1712 forum posts
20 photos

I've found that too, and it seems tightening to just under flexing the plate is the only option. So I'd be glad too if someone can give us the proper solution.

John Haine31/08/2021 17:17:48
4188 forum posts
242 photos

Put the blade on backwards and cut on the pull? Also recommended with junior hacksaws.

Clive Brown 131/08/2021 17:18:01
709 forum posts
33 photos

I start the cut using a standard hacksaw frame, then use the sheet saw when the plate is sideways supported by this initial cut.

Nick Clarke 331/08/2021 17:21:23
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1260 forum posts
50 photos

Electric Jigsaw and metal cutting blade?

JasonB31/08/2021 17:22:53
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Moderator
21467 forum posts
2455 photos
1 articles

115mm angle grinder and thin disc

Bo'sun31/08/2021 17:29:25
517 forum posts
2 photos

John,

I'll try that, hoping I can keep the sheet held down sufficiently.

Nick,

Would need to borrow a jigsaw.

Jason,

It may come to that. I was just hoping for something a little less frantic.

John Haine31/08/2021 18:09:16
4188 forum posts
242 photos

I've now looked up Shetack saws on the web and looking at the pictures I'm pretty certain that one is meant to cut on the back stroke. The plate has to be very thin to clear the saw kerf so can't have much rigidity. If you pull on the cutting stroke it actually takes pressure off the plate and reduces any bending tendency. I always wondered why Junior hacksaws were so awful until someone on here mentioned putting the blade on backwards, it makes all the difference. Like Japanese saws.

Pete.31/08/2021 18:30:19
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648 forum posts
102 photos

I'd use a 32tpi blade for sheet metal.

Ady131/08/2021 18:46:20
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4754 forum posts
715 photos

Nibbler?

DMB31/08/2021 21:05:36
1169 forum posts
1 photos

I have cut 1/8th mild steel with a Bosch electric jig saw and metal cutting blade very successfully but the noise is dreadful. Good ear defenders are a must!

Speedy Builder531/08/2021 21:06:50
2416 forum posts
191 photos

Jigsaw, goggles and ear muffs. Use a bit of cutting oil prolongs blade life. I have even cut 1/4" steel plate this way just with a good old DIY Bosch jig saw and a metal blade.

Simon Williams 331/08/2021 21:22:15
605 forum posts
81 photos

Been here, got the tee shirt!

Firstly you need a fine tooth blade, 32 teeth per inch preferred, 24 TPI at most. A bimetal blade is favourite - you will bend it and kink it to begin with and an all hard blade will snap. Absolutely definitely cut on the push not on the pull. Tension the blade so it isn't tensioned! I know that sounds silly, but having tension in the blade simply bends the backing plate of the "frame". The frame supports the blade but doesn't tension it in the same way as a conventional hacksaw frame does. It transfers the force from the handle to the front of the blade and the skill is in keeping the frame straight.

Now for the difficult bit. There is a knack to pushing the blade against the sheet material so you don't bend the blade and the saw frame. Having the saw at an oblique angle to the cut helps reduce the eagerness of the frame to bend.

The secret to success is not twisting your hand as you push the blade through the cut. Its very easy to introduce a twist of the handle which creates the kink that is driving you crackers. You need to hold the handle of the blade so it prevents the frame from twisting, not introduce a twist. You push the blade in a dead straight line.

Initially you don't put much down force on the blade, so as to minimise the force applied along the length of the blade. As you get better at it you can introduce more cutting pressure and better progress.

As has been said above, once the 1 mm thick cutting disc got invented these things were obsolete.

Good luck!

bernard towers31/08/2021 21:51:30
303 forum posts
85 photos

If you keep the saw with a low attack angle it has less of a tendency to grab as more teeth are in contact. I do use one occasionally but am not a fan .

Bo'sun31/08/2021 21:58:14
517 forum posts
2 photos
Posted by Pete. on 31/08/2021 18:30:19:

I'd use a 32tpi blade for sheet metal.

Agree, but at present 24tpi is the best I can do.

Michael Briggs31/08/2021 22:48:54
217 forum posts
12 photos

As JasonB suggests, angle grinder with thin disc. If you are cutting straight, clamp a sacrificial length of angle as a guide. The angle won’t suffer much.

Michael Briggs31/08/2021 22:48:55
217 forum posts
12 photos

I pressed post once, generated two

Edited By Michael Briggs on 31/08/2021 22:51:34

Pete.31/08/2021 23:28:03
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648 forum posts
102 photos

Is there a reason for using a hacksaw blade over a slitting disc on the angle grinder?

Bo'sun01/09/2021 07:51:32
517 forum posts
2 photos

Yes, as I replied to Jason, it's somewhat less frantic.

Pete.01/09/2021 16:43:03
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648 forum posts
102 photos

Order a 5 pack of good quality 32tpi blades and give your saw a fighting chance of doing its thing.

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