Thread: Making a Pan Brake "Folder with fingers" for home

Here is a reader. http://www.cadsofttools.com/download/abviewer.zip

Thanks Fossil

I am sure you are right about the rib. I was only going to use hydraulics to try and equalise forces by applying equal power over shorter distances to minimize deflection.

Thanks for the link to the viewer however what I need is an autocad version converter. Turbocad V8.2 will only read autocad DXF or DWG files if they have been saved in Autocad version 14 or earlier. The files on the thread are later files so I couldnot read them. Here is a link to a file convertor I have just downloaded and it works
http://shareware.pcmag.com/product.p...SiteID%5Dpcmag

Regards Robin

Originally Posted by ROBIN

I would like to make a wider folder (1200mm). I agree with all the points made about the increased stresss and the problems with deflection. Obviously I would have to use heavier materials. Any thoughts on how much heavier would be appreciated.

Hi Robin,
I am all for anyone having a go at this sort of stuff, but I sincerely believe it may be more difficult than you think.

A few entries up,I wrote about the dimensions of the school 900mm (36") folder. It is is only another 300mm wider but the bridge section equivalent is 30mm thick in comparison to the 12mm section dimension of the sample under discussion. Once you start talking increased widths the section thickness dimensions rise exponentially.

If a 1200mm W unit is desired, I see little advantage in self fabricating. The costs and efforts associated with the working of the heavier sections are well outside the usual capabilities of most diyers and home workshops

I would be seeking a second hand one through auction.
Just an honest opinion
Grahame

Hi robin, as pointed out going wider means a lot of structural re-inforcing required, the expense in doing this far outways a cheap large used unit which has a lot better and easier adjsutments, this size is good becuase its compact, doesnt take up much room and can be put away in small workshops, the current cross arm support angle even at 12mm is right on the limit, when you fold something 1.6 for the full length you can see it just flexing so if anything was to be beefed up to start with it would be this. Also when you go wider the force required to hold a sheet of steel let alone bend it is quite large, this is why commercial 1200mm wide units have a 10 kilo overcentre arm just to hold the sheet in place.
The only other alternaive would be to make a pan brake with a straight plunge, that is the fingers come straight down into a pre machined 85 degree angle, this accomodates for less stresses on the folder but will only do 90 degree bends.

Simso, thanks for the clear, very well illustrated building instructions and plans.

I'm an aircraft engineer and have a Homebuilt project lurking in a friends shed till I get a garage.

From my distant recollections of my apprenticeship (RNZAF), I remember the aircraft bend brakes have three adjustments, set back like yours, but also the lifting assembly being adjustable in height and gap from the bed (to adjust the radius which the edge of the lifting assy swings through.

As 2024 T3 (and more so 7075 T6) have significant minimum bend radius, I would like to implement these adjustments.

Have you already had any thoughts alone this line you could share please?

Regards,
Mark Wrathall.

Robin,

There is a set of plans for a well designed 8 foot brake available from Macs Machines:
http://www.macsmachine.com/

Obviously a machine this size and weight is limited in the material thickness (It is designed for 0.040" 6061 T6 at the full width.

I have his plans and have studied them. Obviously a lot of engineering experience has flowed into that design.

Mark 7075 t6 is hard stuff, even with hydraullic benders you can fracture the sheets at a 90 degree bend, I would recommend maybe leave it in the t0 condiiton and then heat treat it in its final shape for the t6.

This folder is only for light duty stuff, simple design allowing anyone at home that does there own rust work or panel beating or needs to make a box up ect, I have a few mates in the panel beating field and they love it, becuase for them it takes up no workshop room and makes the quick patch panels absolutley easy. For anything other than this I would recommend purchasing an industrial/commercial unit.

Remember every design has limitations, exceed those limitations and its usually easier to start with a completley new design. But feel free to alter any part of my design as you see fit, for your purpose, just simply post results achieved if you could of that alteration.

Steve

Thanks for the replay Steve. The Mustang II only used 2024 T3 and I think the thickest structure is either 32 or 40 thou, so your design will be great.

Once I studied the directions a bit closer, I see you have mentioned in Post #26 that there is vertical adjustment of the folding brace assy, but it is not clear to me from the pictures and drawings how this works. I'm a little confused between the welded and bolted parts there.

My picture is actually a bad example, I just noticed on this one I didnt use a bolt I simply welded for ridgidity as all my bends I want hard sharp angles,
The attached photo shows the lifting assy arms, simply bolt the arms onto the main body, adjustment is made by there relationship "hole postion" against each other, the body itself has elongated holes to allow up and down movement.

Thanks Steve. Yep it was the weld that confused me.

I have modelled the bender, which sure helps understand the details.

Is there a reson for the flat bed to overhang the side pieces by 4mm each side?

I notice Ron's angle iron clap brace is welded at a much steeper angle and further fwd than on yours. Is that the difference between the brake fingers being milled at 45 instead of 40°?

I found a bit of interference when I modeled the bender:

If the distance between Flat bed fastening holes is 664mm, and the attaching threaded holes are located on the center line of the 12mm end pieces, then the angle iron clamping piece needs to be 676mm + little tolerance instead of 675mm.

Nope, you can make it larger if you want, but 675 allows the end pieces to butt up with a 1mm gap on either side to allow welding penetration, if there was no gap then any weld you did would just bead on the top surface of the metal, also yes rods fingers were milled at a slightly steeper angle

Thanks for the prompt reply Steve. theoretical 3D model collides with practical manufacturing - beginners error

How did you approach the kinematic design? Did you mock up the cams and arms in 2D to optimize the final geometry?

This is a very impressive piece of work. Thanks for your generosity in sharing it.

Nope, just used a lot of industrial size machines at work and new what I liked and disliked, then worked out the lack of mass component and compensated accordingly. Dont get me wrong this is not the be all and end of all of benders, its small and practical but has many limitations