Fish Scale Torque Wrench

[pinkflames420]

I know a lot of you guys have your own actual torque wrenches, but my options are very limited due to the availability of things in my area. So please, this is for anyone who is looking for a quick and easy way to torque your bolts, without having too spend a bunch of cash. In total it cost me $5, since I already own a few ratchets. 

It seems I cannot, for the life of me, find a 1/4" torque wrench with my requested settings in the midrange. So I came across a way to torque your bolts with just a ratchet and a fish scale. Of course foot/pounds is the amount of force given at a certain length which in this example Using foot pounds we can use a 12" ratchet to make things simpler. If we are looking to use 15ft/lb of force, we place the scale at the 12" inch mark from the end of the ratchet and pull on the scale to 15 pounds. We have now placed 15ft/lb of force. 
If we are using 6"s as our mark(if you have a smaller ratchet) we would simply use 30 pounds of force on the scale to make up for half the length.
I also did some more research, thanks to forum members, and found a formula to help calulate the weight of the ratchet throwing off your settings..."""To derive this value, he proposed to weight the wrench and find its center of gravity by balancing it on your finger, and the “self-torque” is the weight of the wrench times the distance from the square drive to the center of gravity"". We would then subtract this number(in/pd, ft/pd etc.) from our required setting and this should give the amount of force needed on the scale.

My apologies if my(LONG) explanation isn't as thorough as it could be, but I think this is enough for a basic explanation and to help anyone out looking for quick cheap way to torque bolts.
Depending the quality of the scale, and how accurate this method can be,  I can only give the advice, so please use at your own risk. 

[AtariGuy]

If my high school science serves me correct, the fish hanger scale only shows the force of gravity acting upon an object (weight) rather than the counteraction of force against a stationary mass - but thats just splitting hairs on a technicality. Realistically, you've got a good method of reproducing torque, but there are factors that would throw your measurements off. Namely the weight of your wrench, any pressure you might be using to hold the wrench on the bolt (besides the pressure of the scale), and friction. You may be getting that scale to read 15 ft-lbs, but the fastener may only be getting 8-10 ft-lbs.

I dont know what access you have to ebay/amazon, but there are torque wrenches that can be shipped to your door. It just takes a little patience =)

[gsx600racer]

Iv never seen or heard of this. I do know when it comes to a torque wrench you dont go cheap. This vid will explain why.



I am not discrediting the idea the fish scale idea, but when you are torquing down bolts, you want consistency. Also understanding the difference between in/lbs vs ft/lbs and you don't multiply or divide by 12 to get from # one to the other.

A 6mm head bolt being torqued to 10 in/lbs does not feel like much, torqued to 10 ft/lbs chances are the stud will break or threads will strip before the wrench clicks.(dont ask me how I know this).

I always wondered how accurate the harbor freight digital torque adapter would be(see vid). One thing I disagree in the vid, when applying pressure at the handle of the tool, you should also support the center(where the tool rotates). You don't treat the torque wrench like a breaker bar, you will loose accuracy.

[pinkflames420]

Well eventually I will have to get a new torque wrench, since the one I own is 10-150 foot pounds. I think I am just being a liiiitle impatient lol. I hope it doesnt end up kickin me in the butt. I think the torque wrench is the only thing I've kinda gone cheap on. But your definitely right about it not being fully accurate. Hopefully tho, it would be consistent with each set of bolts you were to torque.
You guys are getting my hopes down LOL do you think it's reaaally not a good idea to use this method on my cylinder head bolts?
I am eager to get my kit put on when it arrives.. any day now muahaha
EDIT: I managed to find a simple formula for finding the self torque of a ratchet. I'll make an edit in my post^^^This should help a bit in making this method more accurate. Thanks guys, or I wouldn't have done more research

[bluegoatwoods]

For what it's worth, pinkflames, you shouldn't be shy about long explanations. We're all interested in what each other might be thinking.

I once made a torque wrench using a coil spring. I took pics and I think I've still got them on another computer. I'll have a look and maybe come back and post them here just for fun.

But I wouldn't trust my home-made torque wrench for any critical fasteners.

[pinkflames420]

Feb 11, 2017 22:02:25 GMT -5 bluegoatwoods said:

For what it's worth, pinkflames, you shouldn't be shy about long explanations. We're all interested in what each other might be thinking.

I once made a torque wrench using a coil spring. I took pics and I think I've still got them on another computer. I'll have a look and maybe come back and post them here just for fun.

But I wouldn't trust my home-made torque wrench for any critical fasteners.

Thanks, bluegoat. Like I said I hope it doesn't kick me in the butt. But maybe once I get a REAL torque wrench within my settings, I could possibly test this method and see how well it works. For future reference of others and for myself  I also like the idea of the scale being able to read from 0-50. I'd hope the scale would be accurate all the way thru.
I also wouldn't mind seeing your pics! I think it would make me feel better knowing I'm not alone in this DIY phase LOL

[bluegoatwoods]

I'll certainly look for them and post them here. It shouldn't take long.

I'm also a fan of home-spun engineering.There's some construction in my house that makes my wife cringe. She figures that if you didn't buy it from Lowe's or Home Depot, then it's illegitimate.

There used to be an arch from our stairway to our back door that I made out of 2 x 4s. If you imagine an arch with legs lined up North-South, then this particular arch had one leg pushed off the the East a bit. Or you could say that this arch extended into two perpendicular planes. It had to be that way because that's where the foundations, in relation to the load, were.

I thought it was amazingly graceful from some angles and, at least, decent looking from others. She thought it was another one of her husband's crackpot ideas.

She managed to get rid of it when we did some fairly large indoor remodeling. She had the kid we hired to do the heavy work take it out and replace it. He replaced it with 2 2 x 8s nailed together. Oh, yeah, big improvement.

For that matter, I'm also going to have to undo some of that kid's work in the bathroom if I ever need to repair that bathtub drain pipe. I had access to that. He cut me off. And I allowed it in order to make my wife happy.

But I'm rambling now. My real point is I love DIY engineering. Be sure to post any other ideas you might have.

[pinkflames420]

You know there are just some things you gotta do for the Wifey, I can TOOOOTALLY understand Buts it's also nice to have a handy MAN around the house, never mind a kid lol.
It's kind of funny because I'm more of the DIY than my husband. Half of the fun is getting there and if I can find a cheaper effective way then sure. Like fixing my own scoot sounds cheap and hopefully effective LOL my confidence is slowly rising.

[bluegoatwoods]

Those Snap-On vs Harbor Freight calibration videos above are interesting.

It wouldn't be too hard to check our calibration at home using a bathroom scale. A jig of some sort would be needed to hold the torque wrench steady while the force of turning is applied to the scale.

It wouldn't be all that accurate. But each individual user would hone his/her accuracy over time.

[pinkscoot]

Pink Flames here is a Tecton  1/4" torque wrench on Amazon.

[pinkflames420]

Feb 12, 2017 12:00:49 GMT -5 pinkscoot said:

Pink Flames here is a Tecton  1/4" torque wrench on Amazon.

Thanks pinkscoot, that wrench is perfect for my settings.
Ive also heard the Harbour freight didn't have the greatest products, but im sure they have there good and not so good depending on your needs. It seems in the video the HF wrenches are fairly accurate actually.

[pinkscoot]

pinkflames420 the Harbor Freight torque wrenches are on a lot of lists of what not to buy from Harbor Freight. I own several and they have screwed me several times. I now have an AC Delco digital one and it seems to work well.

[bluegoatwoods]

I'd better be careful. I have Harbor Freight torque wrenches in all three sizes.

I guessed that they probably aren't the most accurate items on the face of the Earth. But I also figured that they probably aren't inaccurate enough to damage fasteners.

Now I'm going to have to do some thinking..........painful as that is..........

[bluegoatwoods]

Okay, now....here's an idea for a rig that ought to measure the accuracy of a torque wrench.




The torque wrench head is on a bolt that's passing through that junction in the rig. The strut of the rig that points toward the right swivels freely on the fulcrum of the rig. Another strut reaches down to the surface of a bathroom scale.

If the strut that reaches down is exactly one foot to the right of the fulcrum, then 50 ft/lbs of force applied by your hand to the torque wrench would register as 50 lbs on the scale. If the down strut were 6 inches from the fulcrum, then 50 ft/lbs by hand would register as 100 lbs on the scale. Different degrees of sensitivity could be reached by playing with these lengths.

One could calibrate the scale itself using a known weight. A 50 lbs sack of salt would be a good example. Adjust the scale to read 50 with that on board and you'd be okay. If, then, your torque wrench, set at 50, doesn't click until your scale reads, say, 65 then you know that your torque wrench is calibrated pretty badly and that you'd better take this into account.

It might be difficult to make this rig accurate enough for a 1/4" drive torque wrench measuring inch/lbs. But if you made that horizontal strut and it's downward leg, say, four feet from the fulcrum and used a postal scale you might get the accuracy that you need.

And here's the photos of that torque wrench I made some years back. I had forgotten it's purpose until I dug out these pics again. It was meant to measure the torque I was applying to bicycle spoke heads.









And as long as we're letting our imagination roam a bit, let me see if I can find something that might be interesting.......Yes! Here it is.....It's a design for a bicycle dynamometer. I never really even meant to build it. I was just playing with the idea.

This could be modified to work on a scooter. The dyno brake could be applied to the scoot's rear tire. That is, with an adequate water supply for cooling. Anyone who tries this had better be very sure of that.

[pinkflames420]

Feb 12, 2017 19:27:07 GMT -5 bluegoatwoods said:

Okay, now....here's an idea for a rig that ought to measure the accuracy of a torque wrench.




The torque wrench head is on a bolt that's passing through that junction in the rig. The strut of the rig that points toward the right swivels freely on the fulcrum of the rig. Another strut reaches down to the surface of a bathroom scale.

If the strut that reaches down is exactly one foot to the right of the fulcrum, then 50 ft/lbs of force applied by your hand to the torque wrench would register as 50 lbs on the scale. If the down strut were 6 inches from the fulcrum, then 50 ft/lbs by hand would register as 100 lbs on the scale. Different degrees of sensitivity could be reached by playing with these lengths.

One could calibrate the scale itself using a known weight. A 50 lbs sack of salt would be a good example. Adjust the scale to read 50 with that on board and you'd be okay. If, then, your torque wrench, set at 50, doesn't click until your scale reads, say, 65 then you know that your torque wrench is calibrated pretty badly and that you'd better take this into account.

It might be difficult to make this rig accurate enough for a 1/4" drive torque wrench measuring inch/lbs. But if you made that horizontal strut and it's downward leg, say, four feet from the fulcrum and used a postal scale you might get the accuracy that you need.

And here's the photos of that torque wrench I made some years back. I had forgotten it's purpose until I dug out these pics again. It was meant to measure the torque I was applying to bicycle spoke heads.









And as long as we're letting our imagination roam a bit, let me see if I can find something that might be interesting.......Yes! Here it is.....It's a design for a bicycle dynamometer. I never really even meant to build it. I was just playing with the idea.

This could be modified to work on a scooter. The dyno brake could be applied to the scoot's rear tire. That is, with an adequate water supply for cooling. Anyone who tries this had better be very sure of that.

I have to say, im impressed by your homemade torque wrench. I'm not very familiar with metal work, but if it can be made of wood, I'm Totally for it! 
Do you think it would be safe to try and calibrate my 1/2" torque  wrench to use on my scoot? Or is it just better to forget that , because my wrench is 10-150 ft/lbs. And of course I don't wanna break any bolts. Maybe your calibration method could help see how inaccurate my wrench will be at the lower settings.