Need to cut long thin strips of steel (& plastic) – e.g. with an angle grinder?

[John Smith 47Participant @johnsmith47]

Posted by Sam Longley 1 on 18/01/2022 21:24:02:

Get a bit of fencing wire, or copper wire 1.8mm th & pass it through 2 rollers untill flattened to the right thickness & 2mm wide. That might do the 1.4 * 2mm But I could not suggest 5 mm that way.

Years ago I had one of these cutterIt ended up a bit bent & had the imprint of the toothed wheel though. But cut the metal quite quickly

If it works anything like this video…

https://www.youtube.com/watch?v=HUOcE6onDX4

…then it looks like it the small teeth that grab the steel rather damage it.

And like most (all?) sheers, the steel that is cut off also gets bent & twisted…

[John Smith 47Participant @johnsmith47]

Posted by Andrew Johnston on 18/01/2022 23:14:53:

Agreed that the guillotines that resemble paper cutters do result in a curved workpiece. But industrial guillotines shear without distortion of the work. I have a power guillotine, but a treadle guillotine would satisfy the OPs requirements. However, even a treadle guillotine is probably too large and heavy.

Andrew

Yes the extremely shallow curves of a treadle guillotine look like they would definitely work. However yes, most definitely too large & heavy. I need something I can lift off a table at the end of each day and put onto a shelf.

I'm guessing an 80 ton press could also stamp without unintended curves too…   

Edited By John Smith 47 on 19/01/2022 01:35:06

[John Smith 47Participant @johnsmith47]

Posted by Robert Butler on 18/01/2022 21:37:52:

I would guess the normal production technique would be guillotine, stamp or laser cut. To cut thin material with a circular saw without restraining the material risks kick-back with the potential for serious cuts. As with other posts there is no solution to this problem.

I do find the posts endlessly amusing however.

Robert Butler

 

> To cut thin material with a circular saw without restraining the material risks kick-back
> with the potential for serious cuts.
Can you say more about this?
Do all table saws suffer from "kick-back"?
Or are you saying that a circular saw that is not part of a table is what is dangerous?

(Part of my problem is that I can't find a small precision table saw that is designed to cut metal…)

Nobody seems to have directly mentioned the Dremel I was talking about. (see post #1)
Maybe I could clamp the metal sheet to a piece of sacrificial hardboard and set the depth of the cut to be just thicker than the sheet… (or just use the edge of the bench?)  and then clamp some sort of straight edge on top to run against… 

i.e. I'm thinking of doing what this guy is doing, but this time with everything on a much smaller scale…. no?

 

 

Edited By John Smith 47 on 19/01/2022 02:17:49

[John Smith 47Participant @johnsmith47]

UPDATE:

OK I've done some more research on kick-back.

I found a number of videos about kickback on table saws & circular saws…. particularly when working with wood. I've never done any of the stupid things mentioned and I've never experienced any significant kick-back myself and so I hadn't realised the potential size of the problem.

Strangely nobody in the videos I found seemed to mention kick-back when cutting metal. I'm not sure why. (Maybe it's less of a problem if you just cut over the edge of a bench??)

J

[Nick WheelerParticipant @nickwheeler]

Posted by John Smith 47 on 19/01/2022 01:06:45:

> Cuts made with grinding wheels on thin materials are horrible things.
In what way are they "horrible"?
To get clear, are you calling 1mm of steel "thin"?

rough edged, razor sharp burrs on each face of the cut – I could show you some 30 year-old scars if you like

a cut that is only as straight and consistent as your hand/eye coordination and visibility

the finish of the actual cut edge is utterly dependent on the quality and grit of the abrasives the wheel is made from

pollution from the sparks, grit, noise etc

thin materials build up a lot of heat at the cut edges.

Those all sound horrible; they are worse.

Cutting thin sheet metal with a grinder(of any size, from a hopeless Dremel clone upwards) is a roughing operation, not one that produces the 'precision' finishes and dimensions you're insisting on.

How is 1mm thick sheet steel not thin, when you can shape it with nothing more than your thumbs??

Considering the very small strip you want is normally the waste from using a grinder, perhaps you could clamp your material between two pieces of straight steel and shear it off with a very sharp chisel? A cheap wood one would do the job. You'd still have to straighten it, but at least the cut and size would be decent.

And although you don't want to hear this, not showing at least some of your design is what is causing you all the grief with the advice here. Every part you've asked about should be easy to make as singles. Not being able to make them in quantity is immediate grounds for a redesign. How many times have you been through it removing features, changing materials, swapping to readily available parts that will work almost as well as custom ones, reducing the fastener count or making them all the same, and all the other things that are important for actually developing an idea?

[John Doe 2Participant @johndoe2]

Hi John,

I am not a machinist, but I think that such tiny strips will need grinding to shape – along their length rather than across, as cutting of any sort will impart too much mechanical force and distort the strip. A couple of thoughts:

a) Buy laser cut strips or stock to size but with a rectangular cross section, and grind the angled edge yourself using a belt sander with a very fine belt. You will need to make some sort of holder to grip the strip along its length and hold it against the belt. You could also make an angled rest to ensure the correct angle.

You could even clamp a number of strips together, side by side in a pack, and grind the angle across all their lower faces. That way, the strips will support each other during the grinding process.

b) Ditto as (a), but instead of a belt sander use those flat metal honing blocks I have seen. People use them for truing flat surfaces and honing chisels, but I don't know what they are called. They are about 200mm x 80mm and about 8mm thick in size and various grades are available from coarse to very fine. I think they have a fine diamond grinding surface of some sort?

c) What are your strips actually for ? If you explained what their purpose is, some here might be able to offer a different way of achieving what you need.

d) Invest in some (more) decent lighting.

e) Buy or make an EDM machine – expensive and very time consuming, but puts no mechanical strain at all on the workpiece and can make incredibly fine cuts.

[JasonBModerator @jasonb]

Posted by John Smith 47 on 19/01/2022 01:06:45:

@Martin Connelly
> Buy a suitable mill and some slitting saws.
So the slitting saws would be horizontal, yes?

> Clamp the stock between two plates to support the material.
Sorry I don't understand quite what you mean. Can you say more about this configuration. Are you suggesting using a milling table that can do a very wide amount of travel?

maybe a picture will help, use of a small mill was suggested long ago.

Here is a bit of 0.4mm brass which you can just see the end of on the right sandwiched between MDF and having 2.5mm wide strips cut off it with a slitting saw

Not got a photo of theloose strips but dead straight edge, all equal width, do distortion and minimal burr to clean up, there they are soldered onto another part

Want to use a hacksaw than again clamp the work between boards so it is firm and saw to your line. saw held near vertical so more teeth in contact with metal as the straight length of the blade also helps keep it straight unlike having the blade at right angles to the sheet. Clamping it flat and keeping teh saw near horizontal will be similar

[John HinkleyParticipant @johnhinkley26699]

John Smith47

As you appear unwilling to try any of the suggestions so far, have you thought about a nibbler like This one for example? I have no experience of their use but the accompanying blurb suggests that they leave an undeformed edge in use. Coupled with a simple clamp fence to ensure a straight cut, it might prove a economical investment.

Personally, I would go with the solution posted by Jason, above, though, if you don't have access to a mill, the nibbler + fence would give a very similar result.

John

[WatfordParticipant @watford]

Dare one ask just what these very precise strips, from sundry materials, are destined to be used for?

(Or have I missed something?)

Mike

[Mike PooleParticipant @mikepoole82104]

For material of this thickness a junior hacksaw would be most suitable, some frames allow the blade to be turned at an angle to get the frame out of the way of the material. Using the saw like this can feel a bit awkward but a bit of practice is all that is required. Building prototypes is something that is easier with a good workshop and equipment but that requires a major investment and a learning curve to use the equipment. I understand that coming up with something innovative requires keeping your ideas under wraps until it is proven and protected and obviously an open forum is not confidential. At the moment you seem to need a partner who has good facilities and skills and can be trusted, the parts you are struggling with are a bit fiddly to make but with the right equipment it could be a whole lot easier but limited finance and skills are adding another degree of difficulty. I don’t think people are being unhelpful but the parameter limits you describe make the jobs very difficult indeed.

Mike

[John Smith 47Participant @johnsmith47]

@Nicholas Wheeler
Thank you for the clarifications.

No, I am not going to show this forum the overall design of anything, not least because once it comes to market, you might then want to buy my product and that would be in violation of this forums rules!

You need to let me make my own mistakes, and let what is private stay private.

John Doe
a) Yes, fair point. I shall look out for suppliers who offer a laser-cutting service, next time I am buying materials.
Yes, a good reminder about clamping parts together. I used to do more of that. It sometimes works very well so long as the part is held accurately at 90°.

b) Yes, I use a belt/disk sander, rough & fine hand files, and rough & fine diamond hones

c) In the nicest possible way, I would prefer not to answer that question.

d) You may have a point… but I do already have 3 desk lamps and a 4-way overhead LED room light.

e) Yes, EDM machines are AMAZING. But I dont' have the fixed table-top space, money nor spare time.

@JasonB
Ah I get you re how to use slitting saws. Thanks – good food for thought.

Re hacksawing yes, clamping between 2 boards definitely helps. For longer cuts, what do you do once your cut is deeper than your saw permits? At present I put the hacksaw blade at 45° simply in order to keep cutting. However as I keep finding, it does make cutting straight lines much harder!

@John Hinkley
Good suggestion. Fairly hard to be accurate but when used with a fence it should work OK.
Fwiw, I have a hand nibbler which turns out to make a slight mess of the sheet. I suspect that a powered one would probably work much better. I did a very long cut with one the other day and eventually – even though I was extremely careful and keeping everything dead in line – I was simply too strong for it and broke the tooth off it. I think it didn't like the big curl of steel that was forming due to the length of the cut.

[To get clear, this forum did a hiccup and I lost my other replies. I am not ignoring you others!] 

Edited By John Smith 47 on 19/01/2022 12:57:49

[John Smith 47Participant @johnsmith47]

[Re-written]

@John Hinkely
Not a bad idea, particularly if using a straight edge. 
Fwiw, I have a hand nibbler but it does deform the surface slightly. But maybe a powered one will create a cleaner edge. 

@Watford
In the nicest possible way, I would prefer not to answer that question.

@Mike Pool
Yes I am using 2 junior hacksaws. One I keep straight and use it to start my cuts. The other I keep at 45° which I use when the straight hacksaw no longer reaches.
It's broadly fine but a high level of skill is required and I find myself filing and grinding more than I would prefer.

But NO, I think that overall people have been extremely helpful and for that I am extremely grateful. What gets boring is that for some reason a few people seem to resent… the attention or something… and start having a go at me from all manner of directions. EVENTUALLY I am compelled to respond and then others take offence that I am criticising THEM, when they are the very people I am particularly grateful to. Or they flame me for talking off-topic! 

The other thing you miss is that yes, I am outsourcing where I can, but it always takes at least a 1 week to get some work done, plus it costs a minimum of £40 or £50 for even the smallest job.

You also miss the fact that I enjoy picking up new skills & learning messing about with tools. Plus during the act of fabrication, new insights about the designs often emerge.

OK enough, please can we stick to the question?

Edited By John Smith 47 on 19/01/2022 13:04:57

[An OtherParticipant @another21905]

Have I misunderstood something – it seems long narrow strips of steel, undistorted, are needed. I had a 1 x 1 metre piece of 1mm thick stainless steel cut into 5mm wide strips by taking it to a local machine shop, where they stuck it through a large (2metre wide) guillotine for the cost of a couple of beers. Admittedly not a recurring requirement for me (I still have about half the strips), but the relative cost was negligible, so a repeat order wouldn't have been a problem.

The guillotine blade had a slight 'tilt' from one side to the other, so it had a (very slight) shearing action, and as a result the strips came off with a slight 'twist', which was simply to rectify – after this was done (by hand), the strips to all intents and purposes were undistorted.

The width was catered for by a 'stop' system on the guillotine.

I don't know if this would work with plastic material – possibly it would break.

[John Smith 47Participant @johnsmith47]

Posted by An Other on 19/01/2022 13:13:49:

Have I misunderstood something – it seems long narrow strips of steel, undistorted, are needed. I had a 1 x 1 metre piece of 1mm thick stainless steel cut into 5mm wide strips by taking it to a local machine shop, where they stuck it through a large (2metre wide) guillotine for the cost of a couple of beers. Admittedly not a recurring requirement for me (I still have about half the strips), but the relative cost was negligible, so a repeat order wouldn't have been a problem.

The guillotine blade had a slight 'tilt' from one side to the other, so it had a (very slight) shearing action, and as a result the strips came off with a slight 'twist', which was simply to rectify – after this was done (by hand), the strips to all intents and purposes were undistorted.

The width was catered for by a 'stop' system on the guillotine.

I don't know if this would work with plastic material – possibly it would break.

Yes, presumably the larger the guillotine and the more parallel the blade the better this works. If outsourcing there are many options! But it would be nice to:
A) Not have to uncurl & untwist the metal at all and
B) Be able to do it quickly & easily in my home

I am probably missing something but what about using that Dremel DSM20 that I suggested, which seems rather well designed.

…And then just doing what this guy suggests:

 

i.e. Clamp the steel sheet to a desktop using a piece of straight edge and then run the angle grinder with a cut-off wheel up and down along the straight edge.

…Fwiw, he is using 1.6mm thick "soft aluminium".
But are we saying that the problem is that 1mm thick 430 stainless steel or mild steel plate and 20cm long, would be to thin to cut in this way?

J

Edited By John Smith 47 on 19/01/2022 13:50:24

[Maurice TaylorParticipant @mauricetaylor82093]

Hi, why don’t you use your Dremel and see if it works instead of keep asking others.

Maurice

[Grindstone CowboyParticipant @grindstonecowboy]

I just know there will be some problem with this, but why not use a bandsaw, if necessay with sacrificial pieces sandwiching your metal plate? Something like a Burgess BK3 or modern equivalent.

Also, if you could find a way of reducing your 12 month turnover to less than £85k, you would not have to worry about the VAT.

Rob

[John Smith 47Participant @johnsmith47]

Posted by Maurice Taylor on 19/01/2022 14:03:01:

Hi, why don’t you use your Dremel and see if it works instead of keep asking others.

Maurice

Why? Because I haven't bought it and as a humble novice I am asking others if it's a stupid suggestion and if so for what reason.

@Grindstone/Rob – I can't find a spec for the Burgess BK3.
Fwiw, a supplier suggested the rather dinky little Proxxon bandsaw, with a diamond blade that is designed to cut ceramics tiles… however at just 80w I imagine that the cutting speed would be pretty slow!
Re VAT, it's the other way around. I have opted in. the point is that I am saving 20% of all that I spend.

[Anonymous]

Posted by John Smith 47 on 19/01/2022 15:56:25:

Posted by Maurice Taylor on 19/01/2022 14:03:01:

Fwiw, a supplier suggested the rather dinky little Proxxon bandsaw, with a diamond blade that is designed to cut ceramics tiles… however at just 80w I imagine that the cutting speed would be pretty slow!
Re VAT, it's the other way around. I have opted in. the point is that I am saving 20% of all that I spend.

 

You seem to have ignored my reply on page 1 saying exactly that, I've used a bog standard diamond wet wheel tile saw to cut stainless sheet, no problems with that, glass, porcelain or plastics either. Mines 375w though and you can get them for a lot less than a poxy 80w Poxon.

 

 

 

 

Edited By Mick Berrisford on 19/01/2022 16:12:07

[John Smith 47Participant @johnsmith47]

Posted by Mick Berrisford on 19/01/2022 16:11:24:

Posted by John Smith 47 on 19/01/2022 15:56:25:

Posted by Maurice Taylor on 19/01/2022 14:03:01:

Fwiw, a supplier suggested the rather dinky little Proxxon bandsaw, with a diamond blade that is designed to cut ceramics tiles… however at just 80w I imagine that the cutting speed would be pretty slow!
Re VAT, it's the other way around. I have opted in. the point is that I am saving 20% of all that I spend.

You seem to have ignored my reply on page 1 saying exactly that, I've used a bog standard diamond wet wheel tile saw to cut stainless sheet, no problems with that, glass, porcelain or plastics either. Mines 375w though and you can get them for a lot less than a poxy 80w Poxon.

My apologies yes, I didn't completely understand your comment when I first read it.

To get clear, you are suggesting that I cut my (0.9 to 1.4mm thick) stainless steel plate on a water-cooled machine that is designed to cut ceramic tiles.

It's certainly a radical suggestion!

– How fast does it cut?
(presumably quite a lot slower than an angle-grinder?
I'm guessing RPM is c.3000, whereas angle grinders are more like 17000rpm… but on the other hand no sparks & grindings mostly trapped by the water is a proper bonus.)

– Did you fit a narrow metal-cutting disk (if not you will be cutting an unnecessarily wide channel, no?)

– Do you ever get kick-back between the part and the side-rail?

Has anyone else here tried using a wet tile cutter to cut thin (c.1mm thick) steel sheet?

J

[Robert ButlerParticipant @robertbutler92161]

Posted by Mick Berrisford on 19/01/2022 16:11:24:

Posted by John Smith 47 on 19/01/2022 15:56:25:

Posted by Maurice Taylor on 19/01/2022 14:03:01:

Fwiw, a supplier suggested the rather dinky little Proxxon bandsaw, with a diamond blade that is designed to cut ceramics tiles… however at just 80w I imagine that the cutting speed would be pretty slow!
Re VAT, it's the other way around. I have opted in. the point is that I am saving 20% of all that I spend.

You seem to have ignored my reply on page 1 saying exactly that, I've used a bog standard diamond wet wheel tile saw to cut stainless sheet, no problems with that, glass, porcelain or plastics either. Mines 375w though and you can get them for a lot less than a poxy 80w Poxon.

If in doubt, read the instructions

Robert Butler

[Grindstone CowboyParticipant @grindstonecowboy]

Posted by John Smith 47 on 19/01/2022 15:56:25:

Fwiw, a supplier suggested the rather dinky little Proxxon bandsaw, with a diamond blade that is designed to cut ceramics tiles…

I've not come across diamond blades for bandsaws, that sounds very interesting. Would you have any further information on those, or a link?

Rob

[JasonBModerator @jasonb]

Proxxon do em, not cheap though

[Grindstone CowboyParticipant @grindstonecowboy]

Posted by JasonB on 19/01/2022 20:03:14:

Proxxon do em, not cheap though

Blimey, they aren't are they? Won't be getting any of those then.

Rob

[Anonymous]

Posted by John Smith 47 on 19/01/2022 01:32:35:

I'm guessing an 80 ton press could also stamp without unintended curves too…

If that was an attempt at sarcasm I'd advise you to stick to the day job.

There are bench top guillotines that will cut material without curvature. But they are designed for PCBs, so will cut plastic, but not steel.

Andrew

[John Smith 47Participant @johnsmith47]

Posted by Robert Butler on 18/01/2022 21:37:52:

I would guess the normal production technique would be guillotine, stamp or laser cut. To cut thin material with a circular saw without restraining the material risks kick-back with the potential for serious cuts. As with other posts there is no solution to this problem.

I do find the posts endlessly amusing however.

Robert Butler

> To cut thin material with a circular saw without restraining the material risks kick-back with the potential for serious cuts.

Re kick-backs, it occurs to me that saw blades are probably much more prone to violent kick-backs than grinding disks. Does that sound correct? I mean if for example a cut part on a table saw begins to jam into to the side of spinning disk… on a grinding/abrasive disk it will immediately just grind off some additional material, whereas on the edge of a solid blade that wouldn't be an option an it would start jam, yes?

> I do find the posts endlessly amusing however.

[Author]

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