Need Tensiometer Overhauled

[Dan Jones]

I bought an old Wacline, Inc C-8 cable tensiometer on Ebay awhile ago, and though it's in beautiful condition externally it's out of calibration now by a fair margin. Does anybody know of a good shop to send it out to for an overhaul and calibration?

Dan
warbirds@shaw.ca

[shrike]

Look in the yellow pages for a local calibration shop. They may be able to do it there and save you time and shipping.

OptiMaufaturing in Puerto Rico http://www.optimanufacturing.com/tensiometers.html took over Pacific's tensiometer manufacturing and offer calibration certification as well.

The tensiometers I have are direct reading and include calibration instructions. To wit: hang a bucket with a known weight from the appropriate size cable. Measure tension and note reading. Record and adjust as appropriate.

[Dan Jones]

This one actually came complete with a calibration bar and with it installed should be measuring 188 lbs (+/- 2%) but is only reading around 150. Unfortunately I've never cracked one open before and as there's no information about how to calibrate it internally I'm kinda reluctant to try it myself. It wouldn't surprise me if it's never been opened outside of the factory, and that was obviously a long, long time ago.

Dan

[The Inspector]

Send it to a cal shop or metrology shop, don't try it yourself. Then when you get it back, hang a short (5 to 7 foot) length of say 3/16s 9X9 with a known weight on the end like around 50# from an old weight lifting set in an out of the way corner of the hanger. That way you can see what the tensiometer will read @ a given time (like just before you use it EVERY TIME) because the cable tension can vary a bit depending on heat/cold/humidity and you are operating off a known calibrator. (if you've ever done a line check on a DC-10/MD-11 what was called a 'cable tension compensator' was mounted in the front of the MWW and reacted to the current temps to automatically adjust slightly, cable tensions to the flight controls, as long as the pointer was within chart settings the rig was OK).

[Dan Jones]

No, I'm not going to pop it open myself. There's enough of these older ones out there that someone has to be servicing them. I'm going to talk to our "Stores" guys at work this afternoon and see who they know of. Leaving it hanging with a load on it like that, wouldn't that eventually put a "set" into the spring in the thing?

Dan

[The Inspector]

No, what I said was you leave the 'check cable' with known weight in place, 50# is not going to stretch 3/16 9X9 cable. THEN, when you are ready to check tensions, you take the tensiometer TO the suspended 'check cable' and using the correct block, you check to see if the tensiometer reads within acceptable parameters so you know that what it reads on the in airplane cable is set to the correct tension. When done, put the tensiometer back in it's box so it won't fall onto the floor until you're ready to check the next cable. One calibration check a day should be OK for the entire day. Boeing has 'check cables' in numerous locations in the assembly bays in every factory each one has a routine inspection routine tag attached which is on a tooling inspection schedule and the weight is prominently noted on the attached tag with a steel stamp, and as an Inspector, part of your job when doing tension checks is to check the tensiometer.
Don't EVER leave a tensiometer attached and closed on a cable as it will screw up the tensiometers calibration as you've noted. As with any calibrated tool or device, if it's dropped send it out for a cal check before using it again and put it on a say yearly rotation for re-cal, it's cheap insurance.

[Dan Jones]

Ok, now I'm with you! That make s alot more sense after some more sleep!

That's a good idea and one I'll follow up on - simple and reliable. The tensiometer actually has a checking bar included with it, but I haven't had a chance to check out it with a different tensiometer yet - work keeps getting in the way.

[The Inspector]

No sweat! I'd pass it by a metrology or cal shop just for grins, if you no idea how long it's been sitting around and how many times it's been chucked into a drawer or been dropped, or how it was treated in a past life, a cheap way to sleep better 2 night.

[Dan Jones]

It's definitely going out to a shop for an ITRAN before it goes to work. I'd be surprised if it's been checked anytime that you could even remotely call recently. Looks like I might have found an outfit that works on them - http://www.microprecision.com/instrumen ... .-C_8.html They mention the C-8 specifically and not only offer calibration but repair service as well. It's a real nice, little, 1940's era instrument - even the wooden case is well made.

Last edited by Dan Jones on Sat Feb 19, 2011 9:34 am, edited 1 time in total.

[The Inspector]

Built back when people actually took pride in what they did!?! WHAT A CONCEPT!!!

[Dan Jones]

Truly. Sure looks like a quality unit compared to a plastic, "Made in China" one.

[Chris]

Hey Dan,
Sorry I didn't see this thread sooner. I send all my stuff, torque wrenches, tensiometers and such to Precision Tech in Tempe Arizona. They do good work and pretty reasonable price wise. Certs come back with your tools as well. I don't have their address off hand but you can call them at 480 921-1021

[Dan Jones]

Thanks Chris - I appreciate the tip.

[Matt Gunsch]

My C-8 was just done by National Calibration in Phoenix, they have calibrated it for the last 10 yrs or so.

[John Dupre]

I was given a C-8 about 20 years ago and sent it out to the manufacturer on the data plate. They calibrated it, milled out the "Property of the US Air Force" legend on the data plate, changed the plate serial number to match the scribed number found under the data plate and provided the missing calibration check bar. Since then I have used local metrology shops to calibrate it each year. It is great to have a back up when the shop's only tensiometer is out for cal.