How can I bend this ?

[lfoggyParticipant @lfoggy]

I want to make a straight bend in a 1mm thick sheet of stainless steel along the line in the pic below. The part is to repair a kitchen extactor hood. The bend needs to look neat but the angle is not critical, anything around 30 degrees is OK. I have the usual home workshop tools but no metal forming machines. I realise this job would take a few seconds with the correct tool but I've only got a bench vice and hammers.

Any suggestions? I am thinking to clamp it between two 20mm square metal bars and attack it with a hammer but it probably wouldn't be pretty. This might be an excuse to purchase a pan-folding machine but I really wouldn't use it much and don't have space for it in the shop either….

[lfoggyParticipant @lfoggy]

[HopperParticipant @hopper]

I would clamp the narrow part to a stout benchtop with the line along the edge of the bench and a length of flat bar clamped on top of it. Then you can bend the longer side downwards by hand for the most part. Probably then go along it with a block of soft 4 x 2 pine timber or the like and a 2lb hammer to get it to bend along a neat fold line at the edge of the bench. I would not hit it directly with a hammer or it will mar it.

If it is a tough grade of stainless or work hardened it could be difficult though and require a bit of extra persuasion.

You can lash up an impromptu sheet metal folder from a three lengths of say 2" angle iron with a pivot pin welded on the end of two in a suitable location. Two pieces of the angle iron are clamped onto the sheet metal with bolts either end then the third piece of angle iron is pivoted via the welded on pivots and a suitable lever handle. Plenty of designs on the net, like this one LINK

Been meaning to make one for years but usually get away with the above method. And now my local mens shed has a beautiful new 48" folder so problem solved!

Edited By Hopper on 27/10/2022 12:20:54

[Anonymous]

Posted by lfoggy on 27/10/2022 12:06:10:

Any suggestions?

Find someone with the right equipment. If you are near Cambridge you can borrow my box and pan folder.

Andrew

[BazyleParticipant @bazyle]

There are two kinds of bender. One type clamps the sheet between two plates at the bend line and a hinged plate then pushes over the whole length of the sheet sticking out.
The second type is the 3 point or anvil bender where the item is over a gap between two strips or a bar with a long vee notch and a long often screwdriver narrowed blade shaped bar anvil pushes the sheet into the above gap or vee.
The latter can be achieved with two preferably hard wood strips perhaps faced with 1/8 metal strip or angle iron if available and the gap held with multiple screws along the length. Then an anvil can be made with a strip set on edge into a groove in a stout strip. With this setup multiple G-clamps can then apply the bending force across the assembly.

I would suggest that any hammer use will mess thigs up. Ok for bar but not sheet.

[Ady1Participant @ady1]

Might get there eventually, the tough bit is getting a nice straight bend along the length

[noel shelleyParticipant @noelshelley55608]

Take 2 18" lengths of 20mm solid square bar, clamp in the vice with an off cut of 1.6mm sheet in between them ! Then run a generous weld across the end to join them. You now have a country bender. set the job in between to the mark, clamp the whole lot in a GOOD vice and using a soft head hammer or mallet bend the material to the required angle ! Simples ! OR like Andrew if your near me you can use my gear, I have a bender. Noel.

[Nick Clarke 3Participant @nickclarke3]

Posted by lfoggy on 27/10/2022 12:06:10:

I realise this job would take a few seconds with the correct tool but I've only got a bench vice and hammers.

Any suggestions? I am thinking to clamp it between two 20mm square metal bars and attack it with a hammer but it probably wouldn't be pretty.

I don't know if this is the correct tool or whether it is going to be pretty, but it IS a proper tool, particularly if you fit a through bolt either side to clamp the bars to the sheet – it is called a pair of tinsmith's slips!

[Nick WheelerParticipant @nickwheeler]

If you've only got one to do, then clamping it between angle and carefully knocking it over is the way to go. You'll make a decent start by hand, and finishing with a decently long hardwood(aluminium/whatever) block will give a good result.

Do you have any extra material to make a practice bend or two?

[john fletcher 1Participant @johnfletcher1]

Blimy, looking at Ady1 thread, and saw the price of those 4" Vice benders £48 I have one, and I think it was a tenner or maybe a little more at Harrogate show, goes to show how things have gone up. A useful tool, nevertheless, I have a bender, made at Model Eng class (remember them) all those years ago. John

[lfoggyParticipant @lfoggy]

Many thanks for the suggestions and for the offers of assistance. Ironically I live in the West Midlands, metal bashing capital of Britain. I will attemp the job with a mallet and the piece clamped between two steel bars. Anneal first?

[Nick WheelerParticipant @nickwheeler]

Posted by lfoggy on 27/10/2022 17:52:26:

Many thanks for the suggestions and for the offers of assistance. Ironically I live in the West Midlands, metal bashing capital of Britain. I will attemp the job with a mallet and the piece clamped between two steel bars. Anneal first?

For one 30° bend?

[noel shelleyParticipant @noelshelley55608]

Anneal ? No you will ruin the finish ! Noel

[duncan webster 1Participant @duncanwebster1]

I'd go with Andrew, there must be a tin basher near you, contribute to their tea fund. Annealing stainless is not at all straightforward, likely to end up all warped.

[OldironParticipant @oldiron]

Just take a ride around your nearest industrial estae and look for a sheet metal or fabrication shop. You dont get anything unless you ask. Somebody will point you in the right direction. You could search online for local fabricators and call them and ask. If you were near Corby I could get a local firm to bend it for you. Which ever way you do it it needs to be neat. Good luck.

regards

[MacolmParticipant @macolm]

I sometimes need to do this sort of thing, without cosmetic damage. What works well is to hold the sheet in the vice between pieces of wood or better, faced kitchen type chipboard. This usually needs to be cut specially to fit. Align the chipboard edges and the fold line. The chipboard is potentially sacrificial.

 

Now press a third bit of chipboard so as to produce the bend. However, this will make a curve not a fold, so using a mallet, hammer the chipboard as near the fold line as possible. You can form a good but not fully sharp fold this way, without marking the metal.

 

Sorry drawing is a bit big!

 

 

Edited By Macolm on 27/10/2022 22:11:32

[Nicholas FarrParticipant @nicholasfarr14254]

Hi, I would look for a sheet metal or fabrication shop as Oldiron has suggested, even some blacksmith type places may have a suitable folder, and even if it cost a tenner to have it done, it would be better than messing up valuable metal and far cheaper than buying a machine you may not use again.

Regards Nick.

[not done it yetParticipant @notdoneityet]

Oldiron and Duncan are spot on – just like Andrew.

The general anvil bender is likely to provide a ‘wide’ bend. Most clamp-type folders do a good job with a fairly sharp bend.

Yellow pages, or the equivalent local internet search, will provide a choice of venues for the simple cheap resolution to your problem – without making a pig’s ear of the job or wasting material.

[Howard LewisParticipant @howardlewis46836]

If you cannot find someone with a bender large enough to accept the 320mm width, by allmeans resort to clamping between two substantial pieces of metal, ,or mtwo lengtyhs of angle iron (At least 38 x 38 mm )

Do NOT hammer directly on the metal. You willproduce a series of hammer marks, and an irregular bend.

Instead hold a long length of wood, (Preferably 50 mm square ) and work your way along the metal as you hammer the wood.

In this way there will be no hammer marks and the bend will be gradually formed.

When it is reasonably uniform along the length, at your preferred angle, you have done what you wanted!

Just wipe the metal until acceptably clean, and install.

Howard

[Nicholas FarrParticipant @nicholasfarr14254]

Hi, my "V" block and "T" bar pressing tool that I made, makes neat folds in sheet metal Link and I have folded several pieces of 1.2mm 316 stainless sheet to a right angle, two at a time, each piece being 118mm long.

I don't know if it would cope with a fold in stainless, the length Ifoggy requires though, although he only wants to go to 30 degrees and he didn't say what grade it is. Stainless is tougher to fold than mild steel is, whichever grade you use, and it work hardens on the fold more.

Regards Nick.

[Andy_GParticipant @andy_g]

As Malcolm describes – I have also used this method several times (I have some offcuts of beech worktop that work well for this).

For 1mm stainless, you will need some substantial clamping boards, and a couple of G clamps over the ends to stop them spreading where not held in the vice.

Take it steady, a little at a time, working along the full width of the sheet.

If you use metal clamping bars you will get a sharper bend, but also (likely) scuff marks near the bend.

Edited By Andy_G on 28/10/2022 08:55:34

[Speedy Builder5Participant @speedybuilder5]

Another trick – I assume that the inside face will not be seen. With an angle grinder, grind a groove along the line of the fold and reduce the thickness of the sheet by half (0.5mm deep) on the back face. With minimal blocks of wood as others have shown, folding along the line will be both accurate and will require much less force. In my opinion, do not use a hammer / mallet etc, just leaning on the blocks of wood will be sufficient.

Bob

[MacolmParticipant @macolm]

Andy-G is quite right, 1mm stainless sheet is about the limit of the technique I described, and it will need more than chipboard or MDF. The two pieces of steel sound OK, and a layer of masking tape usually protects against marking. Remember stiffness is a cube law, 0.5mm should be 8 times easier to bend than 1mm! As he says, a hard hardwood piece (eg beech, oak) to make the corner of the bend is indicated, Mahoganoid will be no better than softwood.

If the bend angle is made too great, place the corner edge on a flat (expendable) piece of wood, put a bar 10mm or 15mm diameter inside the corner, and hammer it via a another wood board to “draw" the angle (this will spoil the bar for precision purposes).

On grooving the bend line, this will certainly concentrate the bending. Best would be to mill it with a ball nose cutter, avoid a very narrow groove which may result in cracking. Unless you can keep an angle grinder very straight, the wavering will show on the other side when bent.

Or perhaps start with 0.5mm stainless sheet.

[lfoggyParticipant @lfoggy]

Many thanks again for all the tips.

I ground a groove along the bend line using a piece of steel as a guide as suggested by Speedy (the ground groove won't be visible). Then made the bend mostly by hand and with a rubber mallet and piece of wood. Seemed to work OK and the finished piece is more than adeqauate for my needs.

[Nicholas FarrParticipant @nicholasfarr14254]

Hi Ifoggy, looks a neat job, well done.

Regards Nick.

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