Anyone made a guillotine?

[astro_al]

Plenty of folders on here, but has anyone made a guillotine for sheet / plate?

The bigger the better. I was thinking of hydraulics to get some decent oomph behind it, and buy in some replacement blades for another machine.

Kind of like the shear function on an ironworker, only longer - 1m x 6mm would be sweet.

Anyone got any thoughts?

Cheers, Al.

 

[Omniata]

If you make the blades out of 10mm plate, shape the bottom one flat edge and the upper one curved and "heat treat" them to harden them you should be able to make something pretty cool. Remember to shape and machine them first though, it's a bugger when they're hardened...

Make a hinge from a bolt at the back and use a cam for the front it should give you some good leverage....

They're pretty cheap though so it's completely up to you.....

 

[astro_al]

That sounds like a manual guillotine to me. I have a couple of those already. I want to be able to shear plate / sheet up to 6mm. No manual / cam-based mechanism is going to do that!

Cheers, Al.

 

[Omniata]

Use a long lever hehe

Could add two hydraulic jacks to push the blade down???

 

[astro_al]

Hmmm, yes, good idea. I can't help wondering if you actually read my first post?

Al.

 

[Hitch]

Never seen a home made one myself....

Used plenty of real ones though... Most important thing would be to work out how much force you would need.... obviously, you dont want a straight shear, youd need to produce nearly 300 tons Im no math expert, but if you had a slope of 6mm/100mm, you would reduce the forche so your only cutting half of that 100mm strip at any one time....so your force would be 1/20th of that... I guess looking into ideal rake/shear angle would be a good place to start, bound to be something on the net.
An uprated version of a bench shear might work, perhaps using hydraulics instead of a lever.

Most have some form of hold downs to hold the plate secure also, a series of small rams would easily do that.

 

[Welderpaul]

I've often thought about making one, but the structure required to withstand those forces would be massive. The cost of even just getting the main parts made would seriously outweigh the cost of buying a used machine.
I know the satisfaction of making something like that would be very high, i would consider the costs of getting there prohibitive.

 

[Omniata]

Hmmm, yes, good idea. I can't help wondering if you actually read my first post?

Al.

Sorry, typing too fast and reading too slowly

 

[snowcat]

common method of production machines is flywheel rather than hydraulics, to sheer forces are massive, even a smallish machine is the best part of 2 tons of castings and parts, a fence is a must, the sheering action is relies on kinetic energy to force the blade through........ a 4" straight hydraulic cylinder is going to give you only around 20 tons at best, if I remember rightly a cylinder needs to have a 10 degree start to be 100% efficant........

the problem is even 6 ton of force needs a massive structure.....

blades are not sharp there flat ground stock shimed tight, any twist in the frame and there be out.......

 

[Hitch]

Both our 3mx13mm and 4mx6mm are hydraulics, no flywheels in sight!

 

[astro_al]

Sorry, typing too fast and reading too slowly

S'ok - I like the enthusiasm!

My old kingsland ironworker has a flywheel. They scare me. I'd feel more comfortable with hydraulics.

I think this might be a lost cause... My other thought was to rig up a metalwork version of a woodworking 'panel saw' using a plasma torch instead of the disc blade. So you could put your panel on the rack, lock off the x or y carriage and then cut the line you want in any thickness metal (pretty much) - dead straight, very quick. But then it dawned on me that its a lot of hassle! Probably less hassle than making a guillotine, but still, a bit OTT for plasma-ing straight lines. Whats wrong with a straightedge?

Al.

 

[Shox Dr]

Seems like an awful lot of work, the blade distance needs to be adjustable to take into account of the different sheet thicknesses, and that would be a real pain in the ass.

ebay is your friend

 

[snowcat]

Both our 3mx13mm and 4mx6mm are hydraulics, no flywheels in sight!

thats maybe but over crank flywheel straight guillotines are still the most popular its the easiest (cheapest) way of transferring a huge amount of potential energy into kinetic energy, Iv got an Edwards which is an 80s build, and uses a center flywheel, and has a simple overcentre and clutch... earlier models were end mounted, masses of machinery that needs single stroke apps, use the same principles, power presses, concrete crushers, hay balers etc, hydraulics work fine but are far more costly, something like a press brake where the stroke needs control has to work off hydraulics,a relatively small flywheel spun at high speed can readily harness 100s of tons when coupled to a gearbox.......

 

[Hitch]

I would think hydraulic must be the most popular on larger machines....

 

[snowcat]

I would think hydraulic must be the most popular on larger machines....

dunno mines an 8ft cut up to 1/4", me mates is a 12ft upto 3/8 both are flywheel type, I know crushers and big cap balers admit 100 sometimes 1000s of tons of force through the same principles, the disadvantages is theres no control, hydraulics can be set via the reliefs, a kinetic principle gives out when something goes bang, but a flywheel and clutch offers an extremely quick cycle time............efficancy to power Flywheel every time, control hydraulics every time.....

blimmy this all sounds like the kinda crap I had to write about as a student......

 

[astro_al]

To be honest, I suspect its an age thing. Try finding a non-hydraulic ironworker nowadays.

Correct me if I'm wrong here, but this might have come about due to the fact that hydraulic systems can be stopped / reversed mid 'whack' but a flywheel based system seems usually to need to 'complete its cycle' no matter what.

That said, the only large guillotines I've been anywhere near have been flywheel jobbers.

Not sure that a flywheel approach is more efficient, it merely stores up the motor's output over a period of time and releases it fairly instantly, whereas the hydro pump only activates when required. Probably pretty similar overall?

Al.

 

[Hitch]

The pump is circulating all the time, you use hydraulics for the rake, blade gap and hold downs aswell.

I suppose if it was a production machine, built for cutting one thing, all the time, flywheel might win.

A lot of wasted time going through a whole cycle of the blade, especially if your cutting only a bit of flatbar.
And theres a bit of a safety element aswell, if something goes wrong, you release and it goes up again...as you said Al.

On the age thing, the 4metre machine is about mid 80's, Haco, the 3metre is a much newer Edwards Pearson, thats about 1999 iirc. So one is no newer than Snowys.