Thread: Torqueing screws for cheapskates

I've finally got around to getting my first scope mounts and am in the process of mounting them. I've read a lot about the importance of correct torque on the screws. The thing is, I'm too cheap to buy a torque driver I'll use a handful of times and hate borrowing tools so I've had to contrive a way to get the correct torque with a high degree of accuracy once I've leveled the optics etc. I thought I'd share it for fellow cheapskates.

Based on the engineering toolbox idea of using a luggage scale on a crescent spanner, I'm using the allen key supplied with my mounts with a exercise weight attached by fishing line near the end. Since T=Fa, where a= the length of the lever, with a given weight I can vary the torque by shifting the point along the Allen key it's attached (it's 60mm long). A quick cut with a file so the fishing line doesn't slip off, and I can get the torque within about 1 in-lb. This will work equally as well as the luggage scale method.

I've made a spread sheet to make the calculations easy. In my case, I need to torque the ring screws to 2Nm / 18in-lb. So I enter in 2 in the torque cell, 5kg in the weight cell and it gives me 41mm (0.041m) for my attachment point.

Link

Of course I could pay $10 to get a luggage scale delivered but I already have the fishing line and the weight. With the savings from not buying a wrench I can buy a box of ammo!

Borrow one.

In order of importance:
1. Last tool I lent went 'missing'.
2. Last time I borrowed a tool it broke.
3. I don't know anyone with one.
4. This way is much more fun.

Always identify your target beyond all doubt because you never miss and I will be missed

Originally Posted by MB

Borrow one.

Just buy one.....they are not that expensive. You will use it more than you think and just so quick and convenient.
I bought a vortex one from trademe been bloody brilliant.
You can even spread the payments using afterpay if the initial outlay is prohibitive.

https://www.trademe.co.nz/a/marketpl...ing/3800345795

Originally Posted by muzza

I think you are over complicating the whole procedure.

Don't forget to calculate in the prevailing torque and watch the angle of pull, as well as any wet install torque.

Originally Posted by dannyb

Just buy one.....they are not that expensive. You will use it more than you think and just so quick and convenient.
I bought a vortex one from trademe been bloody brilliant.
You can even spread the payments using afterpay if the initial outlay is prohibitive.

https://www.trademe.co.nz/a/marketpl...ing/3800345795

I think our definitions of inexpensive are different
https://www.trademe.co.nz/a/marketpl...5?bof=ZwMcZ1XO

This version is free...

If you haven’t already fitted your scope you’re welcome to borrow mine. I’m close enough to Carterton that it won’t be inconvenient for anyone.

If you end up having to re torque your scope after your first trip to the range, that extra box of ammo will be handy for re sighting in.

I have done mine up firm by hand for ever...and will continue to do so....

I have done the same (by feel) for ever but since moving to a system where I swap scopes I want to be precise when I change them.
I recently mounted a scope with the rifle in a vice and the scope aimed into the distant farmland. It was interesting watching the cross hairs move as I tightened the screws. I don't think the actual torque figure is as important as the consistency of the setting.

Originally Posted by Micky Duck

I have done mine up firm by hand for ever...and will continue to do so....

I use a torque wrench because I have one from a previous career. Before the torque wrench I used to just crank them up to ‘just before they went loose again’. Never came unstuck with steel on steel but have had the odd whoopsie with aluminium.

https://www.sheldonbrown.com/tork-grip.html

Just to be clear this is not a dig at the method outlined by the OP, I post because anyone reading this thread will appreciate it.

Originally Posted by longshot

https://www.sheldonbrown.com/tork-grip.html

Just to be clear this is not a dig at the method outlined by the OP, I post because anyone reading this thread will appreciate it.

Did you find this through an internet search engine or a you an aficionado of bicycle esoterica?!?

Originally Posted by Steelisreal

Did you find this through an internet search engine or a you an aficionado of bicycle esoterica?!?

Years ago when ordering online was still fairly novel, I looked at buying a torque wrench online, found that website, just quietly I didn’t realise it was a piss take at first, gave up reading about 1/4 of the way through thinking the thing wouldn’t be much use. Also gave up on buying online for a while after that too.

Complete waste of time! Just nip them up firmly with a drop of LocTite on the threads (bases only). After fitting literally thousands of scopes over the past 60 years I believe torquing scope screws has about as much validity as getting 72 virgins after blowing yourself up!

Originally Posted by Shearer

I have done the same (by feel) for ever but since moving to a system where I swap scopes I want to be precise when I change them.
I recently mounted a scope with the rifle in a vice and the scope aimed into the distant farmland. It was interesting watching the cross hairs move as I tightened the screws. I don't think the actual torque figure is as important as the consistency of the setting.

I've done a bunch of scope switching and have never found the torque to make a difference (ring to pic rail screws obviously), using a variety of different types and brands of rings/mount the only ones I've found that were sensitive to torque/installing were Burris XTR rings (due to their different construction).

I never use a torque wrench for scope rings, have installed dozens of scopes and rings of a variety of brands.
I personally think more damage is done to scopes from people using a torque wrench wrong than being over tightened by hand.