Clamping Pressure

[Team Pierson]

Does anyone out there have any experience calculating the amount of pressure needed to securely clamp a workpiece? More specifically, what are the limitations of using a Mitee-Bite Pitbull Clamp that has a clamping force of 3600 lbs. Any charts, calculators or articles would be appreciated.

Link to MiteeBite Pitbull page:
http://www.miteebite.com/products/pitbull_e.html

[dertsap]

personally i really like miteebites
leverage is the one thing to concider when using mitee bites clamps be it the pitbull or the cammed clamps ,

if the part stands too high above the clamps ,it will be launched under a heavy load
the pitbull design is nice , it tends to pull the part down into the fixture where as the cammed tend to lift the part if the sawcut isn t square enough

[Team Pierson]

I agree with all that you say including the leverage that the tool has if the part is too tall. I'm wondering if there are some numbers stating the number of clamps needed per size of part. For example, can you clamp a 2 inch part with only one .75 inch clamp? It might just come down to experience since so many factors are involved.

[dertsap]

probably wouldnt pull out if your not going nuts on it
what you could do if you holding raw stock is run a threadmill across the fixed surfaces to make it serrated , which will give you many more holding surfaces the part is resting against,
if you cut deep enough you can get a really good bite into the part ,
if you don t want to markup the part don t go so deep
we used to make our own cammed clamps and we'd run the threadmill around the clamp ,

[fpworks]

Pierson,
I used to design components and turn key solutions for a high end German workholding and toolholding company. There are WAY too many variables to determine how much force is required to hold a workpiece. Engineering calculations could get you a clamping force vector, but nobody could ever say whether it was enough to sufficiently hold/support a particular workpiece. (frequently, we stared at the monitor and said "maybe it will work")

Seriously, a lot of times it was relying on experience...I collaborated a lot with customers to find out exactly what they were doing and what they expected from the component or system.

For example, just by changing brands of cutting tools can significantly change the results of a workholding system.

As for Mitee Bites...I hate the brass hex cam-style pieces, but I love the pitbull style, especially the knife-edge tool steel variants. I just built a fixture with pitbull clamps that engages the material lower than specified by Mitee Bite, and we can still take a cut that was ripping the part out of a Kurt 3600V.

When you ask whether or not it is possible to clamp a 2" part with one 0.75" pitbull clamp, I would have to say that you're not giving nearly enough information!

Justin

[Team Pierson]

You're right... there are so many variables! I wish there were a formula for our customers. Even if there were it'd probably be so complicated that no one would ever bother to use it anyway.

Well, I'll retire from this thread. Consensus tells me that these Pitbull Clamps are about the best compact workholding devices there are out there. Thanks again for the heads up experience on the Kurt vise vs. Pitbulls. Good to know they're as legit as a vise. Here's what we are doing with them:
Pierson Workholding Ez-Pallets

[dertsap]

team pierson
i was wondering where i remembered your name from ,i read previous posts of yours for your pallet system , thats a nice little fixture that youve been working on ,similar to ones ive made before for a high volume production company except we used the hex clamps ,everything was fixtured heavily , as it was our own product
that type of fixturing is great with repeat and high volume ,the only set back i could see is the fact a guy needs stock that is specific to the fixture rather than the other way around ,
have you concidered making the fixture a little more versitile by making the clamping fixed surface removable and some different standard sized surfaces so a person could fit different sized stock ,
i would definitely have the fixed surface serrated , it will make a big difference with holding the part

[Team Pierson]

dertsap,

Yes, the pallets I'm specifically talking about are our PreEngineered EZ-Pallets that are designed primarily for 1st op cuts that hold standard bar stock sizes. They come in sizes of ½" to 2" in ¼" increments and offer a quick way for a guy to quickly palletize a job. For other sizes a custom pallet would be in order.

Thanks for the serrated edge idea on the fixed side. Any tips on the pitch of the serrations?