torque wrench question


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I thought someone else may have some interest, so I'm posting it publicly, instead of sending a PM.

I'm having to retread some holes in a tractor engine block from 3/4" up to either 7/8", or 1".  They are for holding the front end loader onto the tractor.  No problem with the enlarging, and threading, but my question is about a suitable torque wrench.

7/8" plated Grade 8 bolts call for torque of 454 ft./lb.

1"  plated Grade 8 bolts call for torque of 682 ft./lb.

I want them to be torqued correctly to the maximum torque, as I don't want to break them again.

My largest torque wrench is a 1/2" that goes up to 300 ft./lb.

I've found a used Snap On, without the handles, that's a 1" that goes up to 800 lbs. for $140 on ebay.   I don't know how old it is, but seller claims it works, and I'm wondering if I can get SnapOn to calibrate it.  

The other choice is a torque multiplier for a little over $200 off Amazon.  For anyone that doesn't know, but is interested, a torque multiplier is a geared down head, with another handle that has to be fixed in place, that uses a smaller torque wrench, like my 1/2" one, on one side, and the other side will have either a 3/4", or 1" square drive.  They all have a friction loss factor that you have to figure in.   I've never used one.

I'd appreciate your opinion.   I won't use one enough to justify putting a grand, or more, into a new 1" torque wrench.

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I don't think i know a farmer that owns a torque wrench and i know a few farmers. Their torque method was how much they had to grunt. :D

I'd go with the option that makes sense. Not sure how much the tractor is worth.

My first thought is i'm not sure if the stock torque specs for a 3/4" bolt will scale to a 7/8" bolt. I know that how they determine torque specs is complicated and confusing. A lot of it comes back to how much the bolt will stretch and how much clamping force it exerts. Good luck. I'll be interested to hear what is said.

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Tom, tag people and it let's them know. Public, but doesn't someone seeing the thread when you need help.

My opinion, and fully my opinion is that because it is a tractor and we're taking about standard bolts, a torque multiplier would be perfectly sufficient.  They aren't trusted enough in most high performance shops or aerospace but it's a tractor.. 

With that said, Snap on is my favorite company for precision tooling. ALL 8 of my torque wrenchs are Snap on.  In your line of work, it's a business expenses to buy the wrench, have it done up by snap on, and have a great tool on hand in the future. 

I would go with the used snap on. 

 

I am a tool harder

 

 

Grain of salt required.

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Much appreciated!   I don't use that tractor enough for paying jobs to be able to write it off, or any of the mechanic stuff, as a business expense.  It's 98% for personal use of keeping our place up.  I wish I could write it off, but don't want to be in the unpaid rock busting business in a striped suit.

149 seems like a great deal on that wrench.

I don't know what "tag people" means though.  I don't do any social media stuff other than forums for the subjects that I'm interested in.

Nut, I just pull torque specs off of charts from a Google search.

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Works on phone or computer.  Pull down the "3 bar" menu, choose Activity, Account Setting, then scroll down to Notification Srttings.  There are about twenty of these, but the "Someone Mentions Me" setting is at the bottom.

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Looks like parts are still available for that torque wrench.   Not sure about replacing the handle, but other parts don't look too bad.  Looks like it's still available, so going to buy it now.

https://store.snapon.com/US-Reading-Standard-2-Accuracy-TORQOMETER-174-U-S-Follow-up-800-ft-lb-1-drive-P634633.aspx

I stayed up late watching the ball game last night, and forgot about it until I came home tonight.  I did a google search for the model number, and was surprised to see it's still in the current price list.  Pretty lucky that it hadn't been sold yet, so it's mine now.  We'll see if it was worth the 149 dollar gamble, or money thrown away.  If it turns out to be in great shape, I might even spring for the new handle.  I doubt the seller selling it paid 2400 for it, so I know it's a gamble.

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@Tom King 

Did you price out the oem handle? You may also look loop for a corresponding model number made by BluePoint.  They are snap on cosmetic blemishes I believe. My truck guy used to get us the BP parts CHEAP. 

Without the factory handle, what's the plan? I am not an engineer, but I do believe the handles have a specific bit of flex built into them, so putting a pipe on the end may actually not be accurate for the given torque value.

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That link page has a tab with all the parts on it.  The four foot handle is by far the most expensive part at $365.  I can't figure out why the type of handle would have an effect on how the head reads the torque.

- 168TQP 1 Retaining Bushing 2.85 USD  
 
- 200TQP 1 Access Cover 14.70 USD  
 
- 92TQPA 1 48" Tubular Extension Handle 365.00 USD  
 
AA 56TQP 1 Friction Ball Spring 2.85 US

Preliminary plan was to compare it to my 1/2" torque wrench on a bolt torqued to some high spec on it, and compare what it takes to move it tighter with the 1" one and whatever handle I can find that will fit it.  I know it's not ideal, but should be a lot better than any other low-tech method.

There is an outside chance that the handles for my 3/4" ratchet might fit.  I expect any regular pipe would just bend too much.  I'll figure it out after the head gets here, but for 150 bucks, when the new one is 2,475, it looked like it was worth the gamble.

edited to add:  google found a handle for 160.00

edited to add:  cheapest anyone has the Snap On for is 295       Good thing is that it is available, at least.

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49 minutes ago, Brendon_t said:

I am not an engineer, but I do believe the handles have a specific bit of flex built into them, so putting a pipe on the end may actually not be accurate for the given torque value.

It depends on how the wrench reads but odds are it's differential flex on the lower part of the shaft. Any flex further from the head than the measuring point won't have an impact. Unless your talking about the clicker type but they aren't that different.

Direct_pawl_clicker_torque_concept.png

The torque is measured between the pin that is white near the circle and the red thing so any length added past that point won't have an impact. Things that would in theory impact the reading is if there is something gripping the blue circle or if you use an extension between the torque Wrench and the socket. I guess a cheap junk socket could also deflect causing an inacurate reading but that's unlikely.

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It looks like to me that all that is built into the head on the type this Snap On one is.  The handle, that comes in different lengths, slips over the "handle" built into the head.  The head alone is a pretty big thing.   I don't know how much of the head goes up into the handle, but here are the specs.  The width of the head is 3-9/16"

Head Depth,* inches 2-1/32
Increments 10 ft-lb
Length, inches 66-13/16
Model Follow-up
Range, ft-lb ft-lb
Square Drive, inches 1
Width, inches 3-9/16
Country Of Origin USA
Brand Snap-on

 

All the others of this type I found used were 1,000 and up.  If it's junk, it won't be the first, and probably not the last 150 I've gambled away.

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3 hours ago, Chestnut said:

It depends on how the wrench reads but odds are it's differential flex on the lower part of the shaft. Any flex further from the head than the measuring point won't have an impact. Unless your talking about the clicker type but they aren't that different.

Direct_pawl_clicker_torque_concept.png

The torque is measured between the pin that is white near the circle and the red thing so any length added past that point won't have an impact. Things that would in theory impact the reading is if there is something gripping the blue circle or if you use an extension between the torque Wrench and the socket. I guess a cheap junk socket could also deflect causing an inacurate reading but that's unlikely.

Remind Me: When I'm not Cali Floating.

 

Dang this isn't Reddit!

 

So by this information, in theory the mechanism would work the same if you put a 1 1/2" pipe on the end which would applying all pressure at once, versus a piece of square aluminum with a bit of flex, which would give some allowing the mechanism to sneak up on it.

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I think it will be close enough.  The problem with these bolts is that I don't think they were ever tightened tight enough when the front end loader brackets were put back on, or either like the one bolt that was broken off when I bought the used tractor, and over-tightened.  They used to always come loose, and I'm sure that was some factor in them breaking. 

I used to put a wrench on them, and push it with my foot to tighten them back.  That most likely wasn't nearly enough.  I was afraid to put a pipe on a wrench, and crank on them.

This will be a lot better I believe, and I also have some 1" bolts to tighten when I put the tractor back together after splitting it, so I'll feel a lot better about having a torque wrench for these, around 1" size, bolts for them too.

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4 minutes ago, Brendon_t said:

Remind Me: When I'm not Cali Floating.

 

Dang this isn't Reddit!

 

So by this information, in theory the mechanism would work the same if you put a 1 1/2" pipe on the end which would applying all pressure at once, versus a piece of square aluminum with a bit of flex, which would give some allowing the mechanism to sneak up on it. 

My mechanic of materials teach was an @$$ hole.

Torque or a moment measured around the rotating point being the bolt should be equal to the amount of force times the lever length. If the lever is 10 feet long it'd take 50 lbs to get 500 ft-lbs so theoretically if you could measure lengths and weights super accurately you'd never need a torque wrench. If there was some sort of energy loss, which is the only way that the torque wouldn't transmit fully, it'd take a constant input of energy to keep something bent. I never learned in the multiple physics  classes that there were losses in the moment equation. I guess there has to be losses somewhere because nothing is 100% but i don't think the losses are significant. There might be some very minute heating of the pipe or in the wrench mechanism but that can't be much.

Think of it like this if there was a loss of torque energy would have to go somewhere as sound, heat, or some other energy loss. Troque wrenches don't heat up and the clicking sound is a loss but your at torque when that happens. So yeah pipe on the end should theoretically be just fine.

This is messing with my brain your not nice.

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@chestnut, I nearly suggested the measured lever and weight approach, but it only works (with weights) if the lever is perpendicular to the primary gravitational pull. 

When was the last time you saw a wrench fit a bolt head so that the handle was in the optimal position? :lol:

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1 hour ago, wtnhighlander said:

@chestnut, I nearly suggested the measured lever and weight approach, but it only works (with weights) if the lever is perpendicular to the primary gravitational pull. 

When was the last time you saw a wrench fit a bolt head so that the handle was in the optimal position? :lol:

I could solve that problem but it's not worth it... Sorry tom for the distraction. I hope the ebay wrench works out. Seems like a killer deal and is one of those too good to be true situations.

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Having been in the QA/QC aviation maintenance world for decades, I can tell you torque multipliers are, indeed used. Think helicopter rotor heads (the "Jesus" nut they call it), certain propeller nuts and some landing gear and pintle pin nuts/bolts, among other things. Mostly very large aircraft. So they are accurate enough for your tractor. There are also stretch torques used, lubed vs dry torques... but I digress. On the other hand, for tractor work, there's always a pipe on the end of a wrench if you have a calibrated elbow haha...

I also grew up on a farm and worked ranches with many tractors, and although checking torque is always a good idea for critical installations, I think it was Chestnut, and I agree, who said they didn't know any farmers who used torque wrenches on tractors. The exception would be engine or transmission assembly, not attaching a loader to the frame. Your mileage may vary :) 

Snap-on will happily calibrate and/or repair all of their tools to NIST standards. If you get no joy from the local tool guy, write their customer service department and they will take care of you from the home office. I've had to do that upon occasion, especially for tools I bought 40 years ago that they haven't carried for years, but they will replace what you have with whatever is the latest in their catalogue. That's why you spend more for Snap-on; they are a lifetime purchase for sure.

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I think my arm is not very well calibrated when bolts get over 1/2".   I have a grading blade with hydraulic swing, and tilt.  I snagged a rock down in the ground with one corner of that blade, and it sheared all six of the Grade 8 1" bolts that attach the blade to the tilt swivel plate.  Fortunately, no drilling was required to get those broken bolts out, since the ends protruded past the plate with nuts on them.  I guess I never tightened the replacements tight enough either, because they have loosened since putting the new ones in.

One trouble with hardened bolts is that they snap easier than softer bolts, so being scared of breaking them, I never put enough torque on them.  I need something better than my poorly calibrated arm.

Thanks for the advice Chip.   If this Snap On wrench turns out to be a loss, I'll buy a torque multiplier.  I'm sure it will be good enough for tractor work, but it would be really nice to have this as a working tool-keeping fingers crossed.

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It came.  It's amazing.   There is no sign that any kind of handle has ever been on it.  There are absolutely not even any scratches on the window over the scale.  It's HUGE.

The follow up needle is easy to reset.  The 1" drive lug looks like it might have had a socket on it one time.  The little detent ball is even easy to operate.   With no handle ever put on it, I doubt it has been abused.  Only a few toolbox scratches on the back.  The main part has some sort of film on it, that is hard to get off.

I don't even own a single 1" drive socket yet, so can't try it out any kind of way until I get some.

edited to add:  The film just seems like wax.  Toothpaste on a paper towel gets it off.   What I thought, at first was a cover plate is actually the main structure of the tool.  It's stainless steel, and the top, with all the screws in it, is polished to a high shine.  Looks like someone spent more time taking care of it than using it.

For scale, the deck boards are 5-1/2" wide, and the railroad spike was close by.

IMG_1148.JPG

IMG_1149.JPG

@brendon_t      check this out

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