jscpm
Titanium
- Joined
- May 4, 2010
- Location
- Cambridge, MA
I have a clamp that holds two pins as follows:
Material is 642 bronze. The planned clamping action is by putting screws through the flat part of the clamp to tighten it up.
There are a couple of problems. One is that an interference fit is about 0.001" which translates to 0.0015" on the diameter of the horizontal rod, but with EDM, about the narrowest I can get the slot is 0.01", so there will be a gap. In other words, there is no obvious way to machine a slit so narrow that will close up completely when the clamp is screwed down.
The other problem is that since the clamp is hinged at the round end, my concern is that it will tend to pinch at the square end. In other words, the square end will clamp down, but the rest of the length of the rectangular bar will not be tight. Is this true or not? In other words, let's say we have a #10 screw near the junction of the flat and round parts of the clamp, and tighten it. Will that screw generate enough force to deform the clamp and tighten it down? The goal is to get an even clamping force across the whole length of the rectangular piece (where the horizontal pin goes).
One Nutty Idea: Taper the Bore
One kind of nutty idea I had was to taper the horizontal bore slightly, so that it was wider at the far end of the clamp and narrowed as you got nearer the junction with the round end. The purpose of this is that when you screwed it down, it would have to bend more at the far end and that would compensate for the hinging action (in theory). The challenge is how do you compute the taper? Also, it will be a very slight taper, like 0.005" over 4 inches or something like that, so it would be somewhat annoying to machine that.
Material is 642 bronze. The planned clamping action is by putting screws through the flat part of the clamp to tighten it up.
There are a couple of problems. One is that an interference fit is about 0.001" which translates to 0.0015" on the diameter of the horizontal rod, but with EDM, about the narrowest I can get the slot is 0.01", so there will be a gap. In other words, there is no obvious way to machine a slit so narrow that will close up completely when the clamp is screwed down.
The other problem is that since the clamp is hinged at the round end, my concern is that it will tend to pinch at the square end. In other words, the square end will clamp down, but the rest of the length of the rectangular bar will not be tight. Is this true or not? In other words, let's say we have a #10 screw near the junction of the flat and round parts of the clamp, and tighten it. Will that screw generate enough force to deform the clamp and tighten it down? The goal is to get an even clamping force across the whole length of the rectangular piece (where the horizontal pin goes).
One Nutty Idea: Taper the Bore
One kind of nutty idea I had was to taper the horizontal bore slightly, so that it was wider at the far end of the clamp and narrowed as you got nearer the junction with the round end. The purpose of this is that when you screwed it down, it would have to bend more at the far end and that would compensate for the hinging action (in theory). The challenge is how do you compute the taper? Also, it will be a very slight taper, like 0.005" over 4 inches or something like that, so it would be somewhat annoying to machine that.
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