Testing impact wrenches?

[Jason280]

I would like to set up an apparatus for testing torque wrenches, using standard fasteners in steel plate. The idea would be to use grade 8 bolts torqued to a specific setting using a MAC 50-250lb-ft torque wrench, and seeing how well various impact wrenches do removing the fasteners. I know this won't be a true scientific/lab test, but should give me an idea of which impacts are stronger than others.

Here are some questions I have:

1. What sized nuts/bolts should I use for the higher torque setting?

2. One issue I will run into is my torque wrench only goes to 250 lb-ft, and I do not have access to anything larger. Is it possible to torque the nut to a set number, and then continue rotating with a breaker bar specific distance and then estimating the torque number? Let's say I torque a 3/4" bolt to 200 lb-ft, then rotate it with a breaker bar an additional 90*, can I accurately estimate the amount of torque necessary to remove the bolt?

3. Any potential issues with this proposed set up? I plan on using 1/2" plate with the nuts tack welded in place, which will prevent them from rotating.

Suggestions and tips are greatly appreciated.

 

[beedle]

ir2135 nuf said

 

[ATC]

I'm sorry....what? I can't see anything past your avatar

 

[strikeouttruck]

If you are in cali I have a SO 800 ft lb torque wrench that can be used. I recommend 15/16th bolts.

 

[Fast LT1]

Mg725, go big or get off the Internet.

 

[Jason280]

Its not that I am looking to buy the strongest impact on the market, I'm simply looking for a way to test the impact wrenches I come across from time to time. Right now, I have three 1/2" impacts, an IR 231G, an IR Ti impact (not sure of the model, its a couple years old), and a DeWalt 18v. I have one 3/4", a TSC FarmHand, and a 3/8" Kobalt. I'd just like to see what each can really do. Plus, I come into deals for different impacts all the time, and this would give me a way to test them against the impacts I currently own.

For example, I have a chance to pick up a Sunex 1/2" impact, but I really have no way of knowing whether it would outperform the impacts I already own. Not only that, but it would give me a good indication of when a wrench has started losing power or if its worn out.

 

[trexdoink]

Sounds like allot of work but the results should be interesting. I would should have a 1" bolt for the 3/4 impacts, a 3/4 should do for the 1/2 drives. You should have a big torque wrench or it's a moot point testing them at all. It would be interesting to know different line pressures and with different size hoses. Just my thoughts.

 

[Jason280]

As I mentioned, I only have access to to a 250lb-ft torque wrench, so its fairly important that I be able to calculate the torque on a fastener above the 250 number.

I have the plate and a good assortment of grade 8 fasteners, so its not as though I have to go out and buy anything.

 

[GSteg]

At 250 ft-lbs, most impacts will break them loose. With that kind of torque, you're basically testing whether the impact works or not. I have a couple 1" drive torque wrench (1000 ftlbs) ready to go, but haven't had time to get all the fasteners needed. I have a bunch of impact guns I would like to test too.

 

[cheechi]

in order to try to torque past where your wrench can measure, interpolate data from what you are able to test.

Set the bolt at 50 ft lb. how many quarter (or eighth etc) turns does it take to get it to 100 ft lb? how many from 150-200 and so forth, get yourself some data points. With as little as two you can use linear interpolation but the more data points you have, you will be able to use the math to see how many quarter turns you 'should' need from one to another, and then see if the interpolation method will work for you. If your real world results are close to what the math says, go for it. if the math is way off what you torqued, you will need a different wrench to measure more.

If you were to start at 50, record each 25 more ft lb, i think your data points would be logarithmic or maybe a simple exponential. Possibly something neat like a geometric sequence. Either way, you will approach a limit as of course your bolt can only be torqued so far before failure.

 

[signcrafter]

At 250 ft-lbs, most impacts will break them loose. With that kind of torque, you're basically testing whether the impact works or not. I have a couple 1" drive torque wrench (1000 ftlbs) ready to go, but haven't had time to get all the fasteners needed. I have a bunch of impact guns I would like to test too.

So would you run the bolt in with the impact and then see what torque it takes to remove it or would you torque the bolt down to say 500 ft/lbs and then see if the impact will remove it?

 

[GSteg]

The latter. Bolt the fastener down and see if the impact could take it off.

I have access to a Skidmore Wihelm at work, which would take the guessing out of the equation, but I'm not suppose to run impacts on it

 

[Guns R Tools]

How about a horizontal metal bar that you can hang/attach weights. And the metal bar pivots on one end that is where the bolt is attached. When you use impact you can measure how much weight it can move up at different distance from pivot point. Kind like balance beam scale. It may not be scientific but it will be repeatable.

 

[dsmnickk90]

How about a horizontal metal bar that you can hang/attach weights. And the metal bar pivots on one end that is where the bolt is attached. When you use impact you can measure how much weight it can move up at different distance from pivot point. Kind like balance beam scale. It may not be scientific but it will be repeatable.

The only problem with this is the Hammering action of the impact is actually what turns the fastener not actual rotational force.

 

[O_M_Jeep]

250 ft lbs isnt going to tell you much, Truck lug nuts are torqued to 475 ft lbs and I take them off everyday with my 1/2" Kobalt impact that cost me $30 brand new with a 2 year warranty.

I also put them on with the same gun, I routinely hit 400-450 ft lbs then torque to 475 with a break away.

 

[Wakefield]

Would most healthy impact guns given plenty of air pressure break/destroy a 1/2" lug stud if you let it hammer for a couple of minutes (1/2" drive air gun) (tightening the lug nut)

 

[joebiodiesel]

This is an interesting read: http://www.ingersollrandproducts.co...es/impact-gun-torque-ratings-science-or-magic

I think your cheapest option would be to get one of these. http://buy1.snapon.com/catalog/item...roup_ID=675248&store=snapon-store&dir=catalog

Joe

 

[daveblank]

Just hunt around for an older used Skidmore tester & call it done.

 

[Murphy4570]

Mg725, go big or get off the Internet.

Pfffff Matco MT1769A is better. Snappy's air tools are OK, but Matco's rebranded IR stuff is better IMO. I really like the composite stuff, it is so lightweight, and hits like a freight train!