Measuring impact gun torque?

[cropwell]

I have tried similar with a M12 bolt and stack of washers, however I suspect there wasn't enough stretch in the bolt/washers to make it accurate enough, as readings seemed to vary quite widely.

My thought this morning was to get a bit bar, drill a row of holes to accept a row of nuts/bolts, torque them down at increasing torques, then see what the gun can slacken. What I really need to know is how tight a bolt the gun can slacken, as I'm wanting to test fi I can replace it with some form of high torque motor/gearbox.

..
You could use a Belville washer as the spring

[m_c]

I've been on the lookout for something suitably springy, such as some Belleville washers.

We used to have truck body front mount springs lying around at work, which would of been ideal, but sods law dictates when you need something, you can't find it.

If I can't find something soon, I'll just have to buy a suitable spring. This is one of those projects that's been continually shoved down the todo list, but is now rapidly approaching the top of the list :-/

[m_c]

Just found a reasonably priced supplier of Belleville washers, so have ordered some M10 and M12 ones to do some testing.

I can now rest easy in the fact I'll walk into work tonight and find the other springs!