Sheet metal saw.

[Bo’sunParticipant @bosun58570]

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.

[Bo’sunParticipant @bosun58570]

Is there a secret to stop it bending?

[Nigel Graham 2Participant @nigelgraham2]

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 HaineParticipant @johnhaine32865]

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

[Clive Brown 1Participant @clivebrown1]

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 3Participant @nickclarke3]

Electric Jigsaw and metal cutting blade?

[JasonBModerator @jasonb]

115mm angle grinder and thin disc

[Bo’sunParticipant @bosun58570]

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 HaineParticipant @johnhaine32865]

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.Participant @pete-2]

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

[Ady1Participant @ady1]

Nibbler?

[DMBParticipant @dmb]

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 Builder5Participant @speedybuilder5]

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 3Participant @simonwilliams3]

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 towersParticipant @bernardtowers37738]

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’sunParticipant @bosun58570]

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 BriggsParticipant @michaelbriggs82422]

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 BriggsParticipant @michaelbriggs82422]

I pressed post once, generated two

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

[Pete.Participant @pete-2]

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

[Bo’sunParticipant @bosun58570]

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

[Pete.Participant @pete-2]

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

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