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Question about Torques and Screws

Question about Torques and Screws

(OP)

Hello,

I found this forum just searching for help on an issue I have with torque/screws, etc. So basically the screws keep getting stripped on an assembly and I have no idea what it could be. I have linked a video with the problem I am having. The torque is calibrated at 50oz.f.in. Does anyone have any idea what it could be?



http://tinypic.com/r/9u2d0m/9




RE: Question about Torques and Screws

What is "stripping?"
- The drive slots.
- The screw's threads?
- The part's thread?

What size is the screw"?
What is the screw material?
How much engagement?
Please describe the torque calibration.
Is there a clutch near the screw, or are you limiting the torque with current6?

RE: Question about Torques and Screws

Please use a non-Flash format for any video you want viewed.

Mike Halloran
Pembroke Pines, FL, USA

RE: Question about Torques and Screws

It is very likely that the torque control of the power screw driver is not precise enough for driving screws into plastic. There will be a torque peak higher than the clutch setting due to friction and to inertia of the rotating parts, which cannot stop instantly.

RE: Question about Torques and Screws

At a former employer, assemblies with overtightened screws and cracked countersunk plastic parts appeared rather suddenly.

We were using Black & Decker battery operated screwdrivers with a green handle and a silver gearbox, which gave good service and consistent torque.

The problem was traced to a new operator, who would hold the button ON until the driver clicked, then release the button (which locked the spindle), and give the driver another 'zetz' manually. She had pretty strong biceps and wrists, so she was getting an extra quarter of a turn, enough to cause lots of trouble in that (not robust) assembly.

I.e., the first thing to do when there's trouble on the line, is go and watch the line, for yourself.
Do not ever delegate the task of observation.

Mike Halloran
Pembroke Pines, FL, USA

RE: Question about Torques and Screws

Mike, you are right on with the don't delegate advice.

Ted

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