Shop safety question

[wilsonmw04]

Greetings,

Background:
Over the summer, my team acquired a manual shear press (link to model).
It has sat in the shipping crate due to a lack of an appropriate stand. One of our sponsors heard of this and created a 33" tall cast iron stand for the press. My administration is balking at the idea of bolting it to the floor. They suggested mounting the stand to a plate instead. They have requested that I do some calculations to determine the tipping risk of the press on a plate of undetermined area.

Questions:
1. How do I go about determining the torque required to shear a 1/8" piece of aluminum 4 ft wide? I am a Physics teacher, so i'm familiar with shear stress and the like, but there seems to be so many variables to this (mechanical advantage, area of the cutting surface, ETC.)

2. Is a plate mounting feasible for this application? (I have never heard of this before)

[Al Skierkiewicz]

Wilson,
Are they suggesting a floor plate that the sponsor's stand would then be bolted to? We used some 1/4" steel plate a long time ago to mount some broadcast film cameras on. It is pretty heavy stuff to try and move around. We ended up putting the plate over plywood and then bolted the whole mess to the floor. It is near impossible to find a flat floor unless certain precautions have been take ahead of time.

[sanddrag]

I've used brakes larger and heavier than that one, with longer legs, and on thicker pieces, I've still had to have a couple buddies pulling on the back to keep from it tipping forward (floor standing unit, not bolted down). It is definitely to your advantage to have the machine as secure as possible. I have seen brakes of the style you linked above bolted to large workbenches, made of 4x4s and a 4x8 sheet of plywood for the top, and that seems to work fine. Since your stand is already made, it looks like you want to proceed down this route. Whatever base you make for it, just make sure it has a really good footprint. If 700+ lbs tipped over onto your leg, you better start looking for a set of wheels.

My question to the administration would be this: Would they rather put four (or more) bolts into the floor, or have a 700 pound machine crush the legs of a student, who can then sue because the administration didn't let them bolt it to the floor?

[wilsonmw04]

They are looking at plate the stand would sit on. I think they have an issue with something being mounted permanently to the floor. I teach in the old "shop" room after they got rid of the shop class. They want an "industrial Expert" to check things out before doing anything. I guess the 3 engineers from Luckstone aren't enough for them...
They just don't realize the scale of what we do. I've brought them into the room, shown them the stand and the shear. I just don't think they get it.

[Al Skierkiewicz]

Well certainly you have to satisfy them. But mounting to a plate brings it's own difficulties. How deep do you put the hardware, how do you tap or otherwise make accommodation for mounting, etc. If the person who suggested the plate is not an expert, it might be better to approach them and see what their hesitation might be. A field trip to an actual shop might even help.

[Dick Linn]

I think you are going to break that shear if you try to cut aluminum that thick. Baileigh makes a unit just like that that is rated for 20 gauge mild steel and 16 gauge aluminum. 1/16" aluminum is pushing it.

http://www.bii1.com/benders/sbr-5220.php