Ideas about angle iron based folder pivot location. (Please advise / correct)

[King tom the first]

Hi, my name is tom and I’m not an alcoholic, hence I’m here at this time on a Friday evening.......
Im looking for input and opinions / facts.
So we are all familiar with the use of angle iron to make a simple sheet metal folding tool.(if not please get yourself up to speed on the concept even if you don’t currently want / care to understand them as I’d like every chance of a sound conclusion!)
My question is thus, if we are folding the sheet around the edge (say formed to a 1mm radius) of the top section of angle (mandrel?) that is used to clamp the workpiece why is the centre point of the pivot the lower moving part (former?) is swung around not in the centre of the radius we are forming the sheet around?
surely this would give us the best chance of a nice tight radius and consistent bend repeatability? I understand that the top section is normally used to adjust for sheet thickness but this could also be done with the lower moving section if made so. This lower section would also need to be positioned more rearward than traditional so it’s resting position sites it at the centre of the pivot point vertically.
Please refer to my colour coded technical drawing of ultimate professionalismness.
Note: viewed from its end.

cheers chaps, tom.

 

[mike 109444]

Your pivot point is in the wrong place.

 

[mike 109444]

Make sense ?
and welcome BTW

 

[gaz1]

this one shows in other details

length can how strong you are comes into it as the folder will fail in the middle

this is the plate type built similer to the old type

near enough old type

al means aluminium

 

[King tom the first]

Hi guys thanks for the welcome, good to know I’m not the only one living the dream on a Friday night.
I understand that’s what seems to be the norm but when you draw it scaled up you see that to get to 90deg you move the top clamping piece back the thickness of the metal to be folded, then to go to 135deg you have to move the top piece back by 2.5 X the thickness of the metal to allow the moving section to lay above the top section with the folded sheet between it. If you leave it set at 1 thickness you’ll be trying to force the moving section through the sheet metal and the clamping section. That’s why I thought having the pivot lined up with the zero of the bend radius would be better?

 

[mike 109444]

You have got no radius on the inside of the fold! (where the blue lines meet at the "v"

 

[Morrisman]

It will also vary depending on the thickness of what you are folding. I guess there is no finite best position. I built one a couple of years ago, and it works quite well, bending 30" wide 16 gauge steel for the bed of my hot rod.

 

[mike 109444]

Extracted page from the good book of Zeus....all praise the word of the book

 

[King tom the first]

cheers for the reply’s guys. The only reason there is no inner bend radius on the last picture is to show how the thickness of the sheet alone makes such a difference before any radius is added.
so we are saying the common hinge location is fine as the top clamping bar is set to thickness plus bend radius due to the radius on the clamping bar being small to nothing meaning it is already out of the way.
Thanks for helping me out there. I was tempted to reinvent the wheel to see if it was better but the materials involved made it more sensible to ask people with more experience.

 

[Onoff]

Thread resurrection but just about to knock up a little sheet metal folder.

Bit of 6"X3" PFC:

Loads of 50x50x6 angle:

Plenty of tube for handles, this and bigger:

Miles of 25x25x2 box if I need any bracing.

I've cheated and bought some 100x20 weld on pinet hinges, coming tomorrow.

Been on here, been on YouTube looking at designs, mine will pretty much be cobbled together in the best tradition of what's lying around.

But...this hinge position thing. Must it be "central" like in @mike 109444 's sketches above? I was watching a Colin Furze video and he put his hinge centre point a couple of mm offset like on the Machine Mart one he was loosely copying from.

Cheers

 

[Onoff]

OK, struggling here with these pinet hinges. Where does the "pointy" bit go? Or should I have got just "round" hinges?

 

[Screwdriver]

Presumably that's a bevel for welding onto. Orient it so that you can weld it??

 

[Onoff]

Presumably that's a bevel for welding onto. Orient it so that you can weld it??

Dunno, there was a video I saw on YouTube (American bloke with a beard) using the same hinges to make a folder. Sure he was saying something about orientating the flats vertical and holding all 4 against a straight edge to align.

Sods Law I can't find the video again!

 

[Onoff]

Found the video! Need to have another watch:

 

[Screwdriver]

Probably not the ideal hinge for your application. Not seeing where that standoff is useful,

 

[Paul.]

I used a couple of 5/8" HT bolts as hinge pins when I built my folder, those weld on hinges are not really up to the forces involved in bending metal,
I cant find a photo at the moment but you can probably see how it works on this short video,

 

[Screwdriver]

Yeah, I was thinking they look a bit weedy. Go large for a folder. Plenty of other opportunities for the design to bend or distort, reduce the number of potential points of failure and overbuild it where you can.

Nothing too strong ever broke.

 

[Onoff]

I hear you all ref the hinges!

OK, it's a case of what I've got. I've some 33.7mm OD galv handrail offcuts. Assuming 3mm wall then that's nom. 27.7mm OD:

I've some 25mm dia X 80 long stainless shafts:

And finally a bit of 1" dia solid ali bar:

Thinking the 25dia shafts inside the 27.7 OD tube as pivots...too sloppy?

 

[Onoff]

Whoops! Just realised the effective working length of this bender will only be about 400mm! OK for what I immediately want it for, to remake this:

No good though when I come to remake my boiler top. Done by hand last time, edges beaten over clamped wood:

Going to cut my losses I think and stop now. I've access to some longer channel I think so I'll get that.

 

[Onoff]

Wondering whether a couple of M16 hex couplers could be pressed into service as a hinge? Screw the bolt in and weld to the LHS one. Cut down the plain shank to become a nom 16mm dia pin sticking out. Stick the RHS coupler in the lathe and run a 16mm drill up it.