Clamping Pressure of Stanley 400

[Framing77]

Hello,

I am a woodworker and any frames I've made up until this point I've joined with glue and with a band clamp. I'm considering purchasing a Stanley 400, based on all of the good things I've heard about them and I'm curious about how they exert clamping pressure, and how much pressure they exert. From a woodworking perspective the pressure should be exerted at 90º to the surfaces being glued, such as in this corner mitre clamping jig:

but the Stanley 400 looks like it exerts pressure at 90º to each frame member being clamped, or 45º to the surfaces being glued. I'd like to clarify this before I purchase one, as they're quite pricey. No doubt I'm missing something obvious here. Or are they simply used to place the frame members together at a perfect 45º, and be nailed, thus allowing the nails to provide the clamping pressure?

 

[JFeig]

The pressure is 90° to the joint.
Think of one rail being stationary in the vise. Then insert the other rail into the vise. It is 90° to the first rail. By screwing in the jaw of the second side, pressure is exerted along the entire second rail. The two 45°s meet and are compressed uniformly along the total length of the miter.

BTY, this Stanley vise was designed over 100 years ago and is still the standard vise design for framemakers in North America, abet many are copycat products.

 

[Ylva]

When I use my vises, I still cross nail as well. I believe most framers do that.

 

[wpfay]

If you look at the jig illustrated, the force tightening the miter, also exerts force against the clamps holding the jig. The potential is to open the inside of the miter from such force.
Other than that, band clamps work very well with frames, just not all profiles. Vises, like the Stanley 400, index off of the rabbet allowing direct and perpendicular pressure to the join. Stanley 400s have always been relatively expensive, but the one I have today was purchased used in 1973 and has been a dependable tool all these years.
If you want to see some mind boggling clamps check out Masterclamps (search for them here, upper right hand corner) that exert about 2000psi on a frame joint, Last i checked, a pair will run about $700.00.

 

[Framing77]

Thanks for your replies. I agree about the propensity of that jig setup to open the mitre 'wpfay', I imagine that the notion there is that you have that set up at every corner and glue & clamp every corner at once, thus cancelling out the opposing forces. A very messy solution, but the image does illustrate the direction of clamping pressure and it's angle relative to the mitre faces very well, which was my issue with the 400. I'll check out the Masterclamps, but at that price I'll just be looking! Thanks again to all for advice.

 

[wpfay]

I think that you need to find a local framer with a Stanley 400 and do a bit of hands on experimenting. Force vector theories are all well and good, but the reality is that the Stanley 400 exerts more than sufficient pressure on the joint in an even manner for the purposes of joining a frame.
Mechanical fasteners are necessary because of the inherent weakness of a miter joint. At some point the joint will fail due to natural expansion and contraction cycles with changes in environmental conditions. Mechanical fasteners can change that failure from catastrophic to a simple repair.

In related thinking, a Hoffmann dovetail joining system provides even perpendicular pressure to the miter faces and are faster than any clamping system.

 

[alacrity8]

Thanks for your replies. I agree about the propensity of that jig setup to open the mitre 'wpfay', I imagine that the notion there is that you have that set up at every corner and glue & clamp every corner at once, thus cancelling out the opposing forces. A very messy solution, but the image does illustrate the direction of clamping pressure and it's angle relative to the mitre faces very well, which was my issue with the 400.

I don't think that most Framers are gluing all corners on a frame simultaneously.
From an engineering point of view, I like the idea of the cauls, but they do nothing to keep all of the wood rails in a flat plane.

I occasionally repair frames with Band Clamps, but I do not like them for new frames as it seems best to glue up every corner at once, and the need to control the movement of 4 pieces of wood with 1 adjustment knob/crank.

I am not a fan of the Masterclamp as there is only 1 knob.

I prefer Stanley 400 and similar clamps as each piece of wood is locked in individually.

 

[Finest Fabric]

The 400's do what they are meant to do perfectly. No need to have a joint so tight you squeeze all the glue out of it!

 

[Romanf]

The 400's do what they are meant to do perfectly. No need to have a joint so tight you squeeze all the glue out of it!

I agree that there is no need to overtighten, on the other hand just because the clamp is capable of extreme pressure, it does not mean that one has to tighten it to the max. I have masterclamps and they are absolutely excellent. Perfect top and back joints every time.

 

[alacrity8]

How does a Masterclamp handle when their is a minor warp?

 

[Dirk]

Gluing up two chevrons and then gluing the chevrons together seems to work best for me. Warping will show up worst on the last corner of gluing the chevrons. If the warp can be corrected with manual twisting, the free hand can tighten the clamp. If both legs need manipulation, find a helper to tighten the clamp. If you're working solo, the handle on the screw just happens to be a one-inch hex. Get a 1/4 inch air ratchet and adapters to drive a one-inch socket, and hook the ratchet to a foot operated air valve. That leaves both hands free to position the moulding. Probably not wise to do this very often as it's likely to cause wear on the screw threads. Love my Masterclamps.

 

[Romanf]

How does a Masterclamp handle when their is a minor warp?

Very well. It has adjustability with spring loaded clamps that latch into the rabbet and also has wheels that change the angle of one frame leg against the second frame leg. Very similar to what you may see on an Alfamachinne underpinner.

It also has a quick slide to lock in your frame, so you do not have to spend all your time turning the handle.

attached are some pics showing how this clamp differs from normal non adjustable units.