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Shear capacity

stevet

Aluminum
Joined
Mar 31, 2008
Location
western mass
I have an old Pexto jump shear.
The tag says 132G, 2-45 ( probably the year of mfg), 18 ga maximum.
I’ve sheared 16 ga in short lengths 8” to 10” and stainless up to 18 ga without much effort.
I’ve seen videos of 2 people jumping on the bar at once and bouncing.
What is the limiting factor of a shear.
Is it the amount of force applied to the bar or part of the casting itself.
I’m interested in shearing 16 ga stainless not full length.
 

Bondo

Hot Rolled
Joined
May 14, 2011
Location
Bridgeton NJ
Call Pexto and see what the capacity is.

The only other option is to keep shearing till you break something you dont want broken.

A shear isn't like a brake, you cant just keep cutting thicker stuff just not full lengths. It will damage the machine and make cutting thin stuff very hard as it will start rolling instead of shearing.

Sent from my SM-G960U using Tapatalk
 

Strostkovy

Stainless
Joined
Oct 29, 2017
Call Pexto and see what the capacity is.

The only other option is to keep shearing till you break something you dont want broken.

A shear isn't like a brake, you cant just keep cutting thicker stuff just not full lengths. It will damage the machine and make cutting thin stuff very hard as it will start rolling instead of shearing.

Sent from my SM-G960U using Tapatalk

Brakes definitely have limits on localized forces. Typically the manufacturer tells you not to use 100% of the press tonnage on less than 60% of the width.
 

Fish On

Cast Iron
Joined
Feb 23, 2014
Location
Mobile, Alabama
I have an old Pexto jump shear.
The tag says 132G, 2-45 ( probably the year of mfg), 18 ga maximum.
I’ve sheared 16 ga in short lengths 8” to 10” and stainless up to 18 ga without much effort.
I’ve seen videos of 2 people jumping on the bar at once and bouncing.
What is the limiting factor of a shear.
Is it the amount of force applied to the bar or part of the casting itself.
I’m interested in shearing 16 ga stainless not full length.

Shears don't cut the whole thing at once - the angled blade means it's only cutting a tiny portion at a time, just like a pair of scissors. So, width of the workpiece doesn't affect the stress on the machine - just the duration of the cut.

If it's rated for 18 gauge 'soft steel' over full length, its also rated for 18 gauge on a piece 2" wide. 16 gauge steel of any length is overloading it. 16 gauge stainless is way overloading it. How many times you can overload it before it breaks? Who knows - those things are reasonably well built, but know that you're pushing it past design capacity.
 

Bondo

Hot Rolled
Joined
May 14, 2011
Location
Bridgeton NJ
Brakes definitely have limits on localized forces. Typically the manufacturer tells you not to use 100% of the press tonnage on less than 60% of the width.
Well I guess I wasnt specific enough. Let me give you the thirty page report on what types, thicknesses and what not all about brakes so I can make a general reference to the difference that brakes can bend more then there "full length" rating vs a shear that cant shear more then the shear "raiting".

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Ries

Diamond
Joined
Mar 15, 2004
Location
Edison Washington USA
I just know that the force required to bend metal goes up with the square of the increase in thickness. Which means it takes 4 times as much force and rigidity of brake to bend 1/8" as it does 16 gage.
I have seen a lot of 18 gage brakes "sprung" in the middle, by trying to push em too far. It means there is a gap between the leaves at full closure in the middle, and it doesnt make a bend that is the same degree of bend all the way across anymore.
Shears, I just see broken ones.

There was a time when sheet metal shops did a ton of custom work in 20 to 24 gage, and bought tools for that thickness- buckets, gutters, ductwork, etc.
And those tools are 1/4 the weight and strength and price of tools for working 14ga to 16ga.
 

dana gear

Hot Rolled
Joined
Feb 27, 2013
Location
Northern califorina, usa
I can save you the phone call, Pexto will tell you the rating listed on the shear is the maximum you can safely shear. And that is taking into consideration that the blades are sharp, and the blade clearance is correct. That said it will shear shorter lengths of 16 ga carbon steel without any problems, 16 ga stainless is going to be pushing it though.
 








 
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