Mounting Adel clamps to larger bolts — what's your workaround?

[ryeoconnor31]

Running into a recurring problem in my fabrication work and curious how others handle it.
Standard Adel clamps are designed for M6 bolts, but we're frequently working with M8, M10, and M12 hardware. Drilling out the clamp hole is usually more trouble than it's worth and compromises the clamp.
What's the cleanest solution you've found? Custom spacers, different clamp types, something else entirely?
Genuinely trying to understand how other individuals/shops handle this before committing to a solution I've been thinking of developing.

 

[Craig Henry]

Adel (cushion, P-clamp, etc.) clamp manufactures have many specialty options other than the “standard” clamps used and sold everywhere. Aerospace companies use them all the time, but you will likely need to contact the manufacture (or distributors) to get a pdf catalog of their product options. I recall using clamps with under and oversized metric (and imperial) bolt hole diameters to secure harnesses to existing hardware. M10 and/or 3/8” is the largest diameter bolt hole I can recall using (15+ years ago.) Any M12 bolt would likely need a custom bracket adapter solution. They will cost significantly more than standard-size cheap knockoffs due to much lower volumes and very high aerospace quality needs.

Good luck,

Craig

 

[gtae07]

All the P clamps I've used came with holes for #10 hardware. I've used #8 a few times, and also drilled a couple out for 1/4in. I don't know if anything bigger would leave enough meat on the clamp.

Could you make a little extension tab that the bigger hardware picks up, and then mount your P clamp to that?

 

[e015475]

The quickest way to do this is to take a die grinder with a tapered carbide burr and hog it out a little. I hold the P clamp in a pair of vice grips and you have to be pretty gentle to keep it from chattering.

If hogging it out compromises the P clamp too much, I'll TIG and #10 screw to the head of the fastener or make an extension tab

I checked Aircraft Spruce and the MS21919 clamps only come in the .199-.207" hole diameter.

 

[Danno1]

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Where I workk we just tap the correct size hole where we need a clamp...


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[larry_g]

McMaster lists a bunch of clamps with a 3/8" mounting hole and a variety with smaller.

lg

 

[sz0k30]

One of my biggest ******* about them is the generally available smaller sizes. Usually the width is only 1/2", so that limits the hole size. Many times, I have made my own - not that difficult. Start with a 3/4" wide strip. Use an appropriate pipe to form the diameter & shape. Drill the hole thru both strips. Cut off the extra length. Radius the ends. Dip in the rubber stuff you can buy to coat things.

 

[kabinenroller]

I have drilled and tapped the fastener hex head for a screw that fits the Adel clamp. This eliminates the need for modifying the clamp.