Run Down Adapters Calibration Processes

[johannajamison]

We have several of Run Down Fixtures/Adapters that we use regularly for torque calibrations. I was wondering if anyone could please tell me a little about Run Down Adapters and their calibration process. We take them apart every so often to grease the parts, but I wonder is there a verification process for checking that a Run Down Adapter is working properly after the device has been disassembled and put back together?

Thank you

 

[mhannon]

I do not believe calibration is required on RDAs. They are only there to simulate a load (a screw or nut/bolt) therefore reducing some of the sharp impact which creates irregular high peaks in torque, thus providing more repeatable measurements.
They will not reduce any of the force, just smooth out sudden impact.

Analyzing a pneumatic driver directly with a torque analyzer will show different results than if you measured the torque on a bolt going into a threaded hole. RDAs are designed to give you results that are more in line with its intended real world use, instead of measuring the output of a driver in a lab setting.

Instead of enrolling them into our calibration program, we keep ours on a preventative maintenance list and follow the manufacturer's (Mountz) recommendation of disassemble, clean, and re-apply molybdenum grease to the threads only, every 6mo.
Every manufacturer of torque analyzer recommends using RDAs (for pneumatics, not hand tools) to improve results, but I have never seen anyone mention calibration.

 

[johannajamison]

I do not believe calibration is required on RDAs. They are only there to simulate a load (a screw or nut/bolt) therefore reducing some of the sharp impact which creates irregular high peaks in torque, thus providing more repeatable measurements.
They will not reduce any of the force, just smooth out sudden impact.

Analyzing a pneumatic driver directly with a torque analyzer will show different results than if you measured the torque on a bolt going into a threaded hole. RDAs are designed to give you results that are more in line with its intended real world use, instead of measuring the output of a driver in a lab setting.

Instead of enrolling them into our calibration program, we keep ours on a preventative maintenance list and follow the manufacturer's (Mountz) recommendation of disassemble, clean, and re-apply molybdenum grease to the threads only, every 6mo.
Every manufacturer of torque analyzer recommends using RDAs (for pneumatics, not hand tools) to improve results, but I have never seen anyone mention calibration.

Thank you for your reply mhannan. We recently purchased a new Mountz 1-10 run down adapter. We check new adapters when they come in and the tool worked correctly when we first tested it. However, it was taken apart last week for cleaning and the molybdenum grease was applied, and now it appears to be slipping/jumping around the 1-4 mark when we use it to calibrate our tools. I was wondering if there is a way to verify the adapters after they have been cleaned and reassembled. Could we do a repeatability test using a power tool?

 

[mhannon]

Which model are you using? I am assuming you are saying yours is rated for the 1-10 lbf.in range?

There are a couple types: manual screw ones which must be manually reversed each time, auto reversing, spring type... there may be more.
I really only have experience with the manual screw ones. If this is what you are using, I can recommend cleaning all of the old grease out first. Don't just re-apply new grease. There could be shavings or other debris that is causing the threads to bind up. We wipe off as much grease as possible, then clean out the threads with alcohol as best we can, then lightly grease only the threads. Don't pack it full, and the washers don't need to be greased either.
If you have a manual type and you say it is slipping/jumping, it sounds like the threads are dirty or damaged.

Also, ensure it is being used correctly if it is a manual reversing type. You need to loosen the bolt after every run. You don't need to back the bolt all the way out, just enough to take the pressure off of the washers inside. Most are only designed to be used in clockwise rotation (tightening the bolt in the RDA). If you test in counterclockwise, you will simply be unscrewing the bolt and not applying any force to the RDA.

As far as verification, If you have a known good DRA, you can take several readings using that one. Then (using the same power tool and torque analyzer) switch to the RDA in question and take several readings. Hopefully they are similar. If not, you have a damaged RDA. I definitely recommend having a couple on hand.

 

[johannajamison]

Which model are you using? I am assuming you are saying yours is rated for the 1-10 lbf.in range?

There are a couple types: manual screw ones which must be manually reversed each time, auto reversing, spring type... there may be more.
I really only have experience with the manual screw ones. If this is what you are using, I can recommend cleaning all of the old grease out first. Don't just re-apply new grease. There could be shavings or other debris that is causing the threads to bind up. We wipe off as much grease as possible, then clean out the threads with alcohol as best we can, then lightly grease only the threads. Don't pack it full, and the washers don't need to be greased either.
If you have a manual type and you say it is slipping/jumping, it sounds like the threads are dirty or damaged.

Also, ensure it is being used correctly if it is a manual reversing type. You need to loosen the bolt after every run. You don't need to back the bolt all the way out, just enough to take the pressure off of the washers inside. Most are only designed to be used in clockwise rotation (tightening the bolt in the RDA). If you test in counterclockwise, you will simply be unscrewing the bolt and not applying any force to the RDA.

As far as verification, If you have a known good DRA, you can take several readings using that one. Then (using the same power tool and torque analyzer) switch to the RDA in question and take several readings. Hopefully they are similar. If not, you have a damaged RDA. I definitely recommend having a couple on hand.

Hi mhannon,

It is a Mountz RDA-10i with a 1/4" Sq. Dr., it must be manually reversed but does have a spring. shown here: RDA-10i Run Down Adapter (mountztorque.com). Thank you again for your recommendations. We will clean it thoroughly and reapply grease lightly, as well as check the threads for damage. We only have one of this kind, so we will purchase a few more in order to have a couple on hand to compare.

Thank you!