I'm wondering what the capabilities are of a couple of flypresses I have
- recent aquisitions. One of them is quite big, I guess it weighs 300 lbs at least, the other one maybe 100 lbs. It'd be great if I could use one of them to punch several 3/16 inch holes in mild steel plate of about 1/8 inch thickness or a bit more. Is this the sort of job for a flypress? I'm thinking of a quicker alternative to drilling.
Fly presses are great tools for all sorts of work. For punching holes to bending or blanking out metal shapes. As youve a 300lb one set that up first. you might find the following useful. 1. with one this size its best to use it standing up. so that dermines the working height of the punch /bed area. 2. its most important to bolt it down onto a metal framed bench, at least 3by 3 by 1/2in angle or welded box.preferrably this frame also bolted to a very strong wall.
Because the work you get out of it depends how rigidly its fixed down.
its important to have different size weights to go on the top cross arm. For heavy work up to 200 lbs, 100 each side of the arm.
then you need room for this arm to clear the wall, and the handle that you pull towards you has clearance also.
A good fly press will have adjustable v blocks to locate the slider in the frame. see that its set up very carefully so theres no play but also no stiffness.
next check the T bolt recesses in the bed, fly presses are scrapped because these are damaged beyond repair.
your punch has to be set in the slider as close to the frame as possible to avoid malalignment with the die it needs to be half hard.
the die should be hard and held in a bolster thats held down by dogs. usually 3/4in t bolts. bring the punch down into the die THEN do up the dogs. check the clearance, and adjust by tapping with a hammer.Finally tighten well. this is called open tooling and will give you production runs of hundreds before you need to check the alignment. when the punch wears, remove it set up in a leg vice and peen the punch to swell the head, replace in the slider then press through the die. this will clear the excess and your back to working again.
If you have got this far, when punching your 1/8in steel, you will need a stripper fork to press down on the work so the punch pulls back out . Theres usually a slot in the back of the frame for bolting one in place.
If youve set it up as above you should be able to punch 1in holes in your 1/8in plate. If you wqnt to go bigger, then you put shear on the punch, equally from each side to the middle. with this you shoud be able to punch holes up to 3in dia. Let us know how you get on. One word of warning, big fly presses are rib /arm breakers. make sure you dont slip when pulling it toward you. Cheers ted dorset UK.
Thank you Ted. That looks like good info indeed, just what I need at this stage.
The larger flypress I have does have wear in the T slots in the base. They are sort of curved underneath where the bolt heads would have beared, curiously. I guess it wore that way from much use. Also, there's some wear in the screw. Otherwise the ram is adjustable and seems fine. I did occur to me at first, to cut up this press for its cast iron, as it was very cheap and pretty thick in places. But I don't think I can bring myself to do that, unless I find out that it doesn't work properly.
Just a side note on flypresses: Some have a double-threaded screw,
that allows you get lots of momentum into the wheel but then also allow you to get lotsa of squidge (one them technical terms, y'know) on the workpiece too. I saw the one in the photo in a shuttered architectural ceramics plant in England, formerly used to press slightly dampened clay powder into a mould.
These are the ones with a screw feed and a long arm with weights on each end to turn the screw? Or the ones like I have, with a flywheel dog-clutched to a heavy shaft with an eccentric making one stroke of the punch for each trip of the dog clutch? An electric motor keeps the flywheel spinning.
It is the sort of job at least for a flywheel press. You need to look in _Machinery's Handbook_ for the formulas, but the required tonnage (my smallest one is a 1 ton, and I have a 2-1/2 ton one. The rating is on the flywheel in the smaller one), is a function of the perimeter length of the hole, and the thickness of the metal (as well as a constant based on what the workpiece material is).
Just working from memory, but I think that a single 5/16" hole in 16 gauge (0.0625" thick) brass (not even mild steel) was the limit for the 1 ton unit. (or was it a 1/4" hole?) With 1/8" thick steel, I suspect that one ton might get you to 1/8" holes, but not much bigger.
So -- you need the tonnage rating of the press. (And if it is the kind with the weights on arms, I suspect that the work required to spin the arms will be not much quicker than using a drill press with a proper spindle speed.
I think your 300lb one is up to the job. any chance of a picture? that will tell a great deal. Dont give up yet. You will need to make some "T" bolts with the T part fitting the t slot properly.approx 2in long will be ideal.This will get over the wear you mentioned. the wear was due to a lazy tool setter using any old bolt. I forgot to mention that if youve several hundred holes to punch youll need to make a x y register to locate the metal your punching. Kep us informed how you get on. Ted
Maybe, maybe not. I don't know how flypresses are rated, but it will certainly be slower than a motorized flywheel pun press.
And the flywheel press "one ton" is the rating -- not the weight of the machine. I can lift the 1 ton one myself -- and walk a short distance with it -- but lifting it higher is a bit of a problem. :-) It is probably somewhere around 75 lbs weight, at a guess. So you might have a lot more capacity than you think.
It would certainly do that -- likely to powder in one stroke. :-)