Thread: A folder photo tour

In Gazza's folder thread, Simon asked for details of the pan brake I have that lives under the bench. Rather than hi-jack Gazza's thread, here it is.

The folder is a Chamber and Corners unit, made in Rocklea QLD some time ago. I believe that they no longer exist now. General tools here in Adelaide has one too - I was told that they keep it there so that they can demonstrate to potential customers how they work before they sell them a Chinese unit. Mine literally does live under the bench. I have it on casters and pull it out when I need to use it. It does have a counterweight on it but most of the time it is off as it takes up space. It's width is 950mm, but I haven't ever bent that width. The largest thing I've done are these (around 600x450mmx450) -


P1010385 (Medium).JPG
This is the device
P1010914 (Medium).JPG P1010886 (Medium).JPG
The basic design is very simple. There is a bed, hinged leaf and a top clamp with fingers
P1010887 (Medium).JPGP1010888 (Medium).JPGP1010890 (Medium).JPGP1010891 (Medium).JPGP1010892 (Medium).JPG
The fingers clamp onto a bar and can be remove or re-arranged by undoing some clamping bolts. The leaf can slide in the hinge pieces. Pictured is the LH one. The BHCS on the side are for the counter weight attachment. The hex head on the bottom is to adjust the leaf position vertically. On the RHS there is a quandrant with a stop bolt so that for repetitive bending it can be set. I've never bothered. The top clamp is pulled down using 2 eccentrics. These are linked using a shaft across the frame.

P1010894 (Medium).JPGP1010895 (Medium).JPGP1010896 (Medium).JPGP1010897 (Medium).JPGP1010898 (Medium).JPG
With the leaf up, the simple nature of the fabricated base can be seen. Like everything the eccentric is solidly made. Throw is around 3/4". Pivots are typically hat sections secured with a thick washer and setscrew. There are oil holes on all pivots. The back pivot for the clamp bar does not move. I can bend material up to around 2.5mm thick (Al). If I need a sharp inside corner I slide the fingers forward a little to the material thickness
P1010885 (Medium).JPGScan5.jpgScan6.jpg
This is how I keep track of bend angle. When the unit is not used I put a thin piece of ply between the fingers and the bed. I have found otherwise that if moisture is around it will wick in and rust. The last two items are a couple of sketches to give an idea of the size of some of the main parts. Duplicating the folder would not be hard if you had a reasonable mill and some way of profiling the plates.
I can provide more details of dimensions if this is of interest.

Michael

Thanks for the details Michael, I'm not sure but isn't there a bit of adjustment on the folding plate, which should allow for thicker/thinner material? To me it looks like the bolt close to where the cantilever bar goes in, moving the fingers forward could damage them.
Kryn

Originally Posted by KBs PensNmore

I'm not sure but isn't there a bit of adjustment on the folding plate, which should allow for thicker/thinner material? To me it looks like the bolt close to where the cantilever bar goes in, moving the fingers forward could damage them.

The clamp bar has no way of moving the whole thing forward or backwards. With the fingers as far back as they can go there is around 2 to 3mm of gap between the front of the fingers and the edge of the bed. The folding leaf (which I think is the cantilever that you are referring to) in it's rest position (vertical) can be wound up and down however, you really want that level with the bed. It not, positioning the material becomes harder.
I am going off what I worked out here - if there is a sheety out there who has better knowledge of what the adjustments are on a folder like this then I'm open to correction.

At the end of the day the maximum material thickness that a folder like this should see is around 1.2 perhaps 1.6 in steel. Sharp inside corners are not desirable most of the time. The folder has suffered over the years before I got it too and the fingers are not straight/ uniform, so tuning it to get it within fractions of mm probably is a tail chase.

Michael

Originally Posted by Michael G

if there is a sheety out there who has better knowledge of what the adjustments are on a folder like this then I'm open to correction.

But maybe it was a long time ago and he may have forgotten.
I think you'll find you are technically doing it wrong. Leaf height is used for metal thickness. The distance the fingers are back control radius up to a point(if you want a large radius you need fingers with a radius on them). I'll try digging through some books tonight.

But as you've found out, at least with thinner material is doesn't seem to matter much which way you do it. 99% of the folding I did was 3mm or less.... as long as you end up with material thickness between the leaf and the fingers when the leaf is up. (or maybe just a tad less) this gives you the smallest radius and means you're less likely to have to start stuffing about with fold allowances......it also puts more load on the folder and is weaker if you are looking for strength.
(Its also lets you tape the leaf and bed for folding colorbond without corstrip(?), or anything else you don't want scratched... though that might work with the leaf lowered.... never tried it)
Playing with the leaf height is generally more painful(though no always) than moving the fingers, either with packing or if the machine happens to be adjustable.

How you adjust the leaf and fingers will effect where you put the foldline to have it centered in the fold.

We uses about 1/2" wide strips in different sheet thicknesses for setting the fingers. If you have one finger that need a little more packing than the rest just put as many layers of tape as required on the back face of the clamp to bring it forward.(assuming they aren't to far out).

Stuart (who said you'd never fold 600x3mm alum with a few pieces of scrap angle iron so maybe you shouldn't listen to him anyway)

Hi Michael,

That's a nicely made folder. I'm still trying to get my head around what the eccentric is for. Is that used to clamp the material and allow for different thicknesses?
For simplicity, could I make a folder where the top clamp merely bolts down onto the material?
It amazes me how strong the fingers are given the distance they are bolted with the set screws to where the material is folded.

I am going to have to make one I think. It will be a painfully slow process though, dealing with such large dimensions (thickness) of steel. Given it's all made from MS is encouraging and the sketches are very helpful....

I'm going to digest the images and have a think. Thanks for taking the time to post these.

Cheers,

Simon

Originally Posted by simonl

I'm still trying to get my head around what the eccentric is for. Is that used to clamp the material and allow for different thicknesses?

Yes - by adjusting the knurled nuts the clamping force can be varied. Clamping is then applied with the lever at the RH end of the folder. You could just bolt down a clamp bar, but that takes time and it is surprising the number of times where I'm clamped up and then decide to adjust things slightly (probably doesn't help that the fingers are not even, so when the fold line is lined up on one it is not necessarily so on another. I need the tape Stuart was talking about).

If you do get serious about fabricating something that weighs a couple of hundred kg say so and I can measure up the various components properly. Chamber and Corners may be gone but their folder design will live on! (just say CC)

Michael

Hi Michael,

I have just re-looked at all your pics and your sketches. It's all starting to make sense now. One part I still can't appreciate is where the fingers attach to. I'm can't visualise how that part gets it's strength. Does not look like a large section.....

Like I said earlier, I have some pieces of steel that would do this job nicely but it would be a long term (bit here, bit there) project. Some of the parts I may need to pay to have cut purely because of size. I have two pieces (slabs) of what look to be BMS. One is about 650x370x19 and the other is (approx) 650x530x40. They both have various holes and slots drilled, bored and milled in them. Obviously the larger piece I cannot even lift let alone cut. I have had these pieces for about 8 years with no way of cutting them or using them but kept them "just in case" This was one of the reasons purchasing the Heska but even this has it's limitations.

Personally, for mine, I cannot find a more deserving project for this steel but I may need to investigate the price for cutting the basic shapes out, or buy myself a plasma cutter. Not sure what they cost, never looked.

I'll have a bit more of a think......

Thanks Michael.

Simon

One thing I forgot to ask. When you say the pivot points are hat sections, does this basically mean dowel pins where the pins are trapezoid in section shape, ie thinner at the top?
If so, are hat sections used as pivot points for better/tighter fit with less movement?

Thanks,

Simon

Scan5.jpg

Hi Michael,

I have been looking further at your folder, in conjunction with the one made by simso (which had it's own thread) and been making mental notes on construction. I think I'm around most of it except for a couple of details. I'm interested in the underneath part of the leaf and how it attaches to the hinge arms. The parts that allow adjustment of the leaf. Is there another piece welded underneath to provide a slot for the leaf to move up and down and then get fixed with the set screws?

Also, the cross section of the finger beam, is that a solid piece of 75x75x98 or is it a type of heavy hollow section? Same with the bed, is it basically a 100x100 angle iron with a 20mm piece of flat bar?

Sorry about all the questions.

Thanks.

Simon

I took the folder to pieces today to get a better idea of the details.
The first detail is because the sketch in post 9 is wrong. While it would work, this is better. The smaller diameter (magenta part) clamps to a non moving part and the larger diameter can turn in the brass bush (blue). All the bushes have oil feed holes too. The advantage of this method is that it allows axial play.

details.jpg

The second section is of a finger mounted in the clamp beam (which is solid). To my surprise the bottom beam is made of angle (around 10mm thick) - probably cut down from 4x4x3/8", with a backing strip welded on the back to make it a closed section. (I'm surprised as it is bloody heavy - I thought it was solid)

The folding leaf bolts onto the back of the hinge (it has slots in it). The bolts are slackened off and the screw at the bottom can push it up or allow it to come down.

Michael

OK. I think I get what you mean. The magenta part is the shaft for the finger beam lifting at the top or where the cam mechanism is?

Simon

Some time next year I will need to make a 6x4 trailer. A pretty much standard trailer but it will need to be beefed up and strengthened for off road use. I was hoping to do my own sheet folding for the trailer but it became blatantly obvious that the folder needed for such a job is way out of my budget and/or ability to make. As Stuart pointed out, the forces required to fold a 1.8M sheet 1.6mm thick are quite large!

Still I have had the need to make some basic stuff out of sheet metal and thin steel and a sheet folder would/will be handy. Was hoping to make a 1200mm wide one but to be honest, one the size of Michael's is probably more realistic.

Michael, do I need to have the hinged parts brass bushed or can they be steel shaft in a steel hole? Maybe I'm being lazy. Perhaps I should just do the same!

Cheers,

Simon

Hi Michael,

If your reading this then have a look at this folder on gumtree:
SHEET METAL FOLDER | Other Tools & DIY | Gumtree Australia Ipswich City - Brassall | 1028309875

My interest in this folder is not to purchase but to get design ideas. If you look closely you will see that the cam lock for the top plate (that holds the sheet down) is acting directly on the plate, so no linkages. At first I thought this was a good idea (simpler) but then I realised that the reason for the linkage is for adjustment of sheet thickness.

Is it fair to assume that any difference in sheet thickness is taken up with the cam action? If so, I can only assume it will only accommodate a small range of sheet thicknesses before the cam takes up in the wrong place and no longer lock down? Unless you can see or know of another method that this would adjust for different thickness sheet material...

Cheers,

Simon

As all good answers start "It depends".
Your clamping force only has to be good enough to resist the tendancy of the sheet to move when folded. However, on a typical folder of that size, the material being folded could vary from say 0.5mm up to maybe 2 or 2.5mm Al. A cam would have to be pretty large to be able to take up that variation and self lock. Without inspecting in greater detail, that folder may have a spring arrangement in there somewhere to allow the cam to lock on a greater range of thicknesses.
The beauty of a cam is that it is cheap-ish, requires no external power source, is fast to apply and is mechanically robust. However, there is nothing that says you couldn't do something differently. The one that springs to my mind is a hydraulic hand pump and a small cylinder or two. It may take longer to set bends up (although not enormously so) but you are not a production facility, so does that matter? The eccentrics on my bender add around 12 or so parts to the assembly, so it would be built faster too - plus if you set things up properly with quick disconnects you could use the pump for a hydraulic press too.

Something to think about anyway.

Michael