Posted by: andrewxl ® 03/16/2006, 13:22:21 Author Profile eMail author Edit

I am trying to figure the torque generate by a certain angular displacement on a bolt head. I am trying to use a pneumatic torque tool for a bolt pattern. Following the sequence i have been checking with a torque wrench and getting an additional movement of the bolt head approx. 3-5 degrees. I would like to know what the additional rotation is equivalent to in torque. The bolt is a 3/4-10 grade 8. Any help would be appreciated.

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Re: torque generation from angular adjustment calculation
Re: torque generation from angular adjustment calculation -- andrewxl	Post Reply	Top of thread	Forum

Posted by: Kelly_Bramble ® Administrator 03/17/2006, 09:49:08 Author Profile eMail author Edit

I think I know what you are asking, however can you please attached a picture or drawing? The rotation you are getting is probably due to the torque wrench being calibrated differently. So, your pneumatic torque tool is applying less torque. What you may realy need is a torque tester to see how much torque your pneumatic tool and torque is actually applying. The amount of rotation is not a good way to estimate torque since there are many variables involved in estimating (thread engagement, material, friction..).

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Re: torque generation from angular adjustment calculation
Re: Re: torque generation from angular adjustment calculation -- Kelly_Bramble	Post Reply	Top of thread	Forum

Posted by: andrewxl ® 04/12/2006, 16:24:43 Author Profile eMail author Edit

You are correct, When we use the pneumatic tool it will stall to torque. In this case the torque value is 325 ftlbs. Since this is a new tool we wanted to verify the torque achieved. We did this using a calibrated click style torque wrench. During this check we noticed that several bolts moved approx. 5 - 15 degrees in rotation. I was looking to estimate the torque difference from pneumatic to clicker wrench using the amount of rotation.

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Re: torque generation from angular adjustment calculation
Re: Re: torque generation from angular adjustment calculation -- andrewxl	Post Reply	Top of thread	Forum

Posted by: rfox71 ® 04/13/2006, 13:00:49 Author Profile eMail author Edit

Take the wratchet and go to one of the bolts that hasent been tightened the additional 3-5deg. reduce the setting on the wratchet a reasonable amount and then try to move the bolt using increasing increments of torque. When the bolt moves you should have a good idea of the difference in the torque settings. You can then test this by offsetting the pneumatic tool the same amt and seeing if you get appoximatly the same amt of movement in a bolt as with the wratchet. mark the head of the bolt to give you reference. I am unsure of the incremental settings on your tools so im not really sure how accurate this will be. You could also go straight to a bolt that has been tightened additionaly with the pneumatic tool and start increasing the torque incrementaly until you get movement, but I think finding the delta with a manual tool will give you more control and therefore more accuracy. Is your supply air pressure right for the manufacturers operating specs on the pneumatic tool?? That could deffinitly be the cause of your error. In any case if that cant be changed youll still need to calibrate it base on your air. Have you tried contacting the manufacturer of the pneumatic tool? They very well might have this tolerance range available. If not you might need to do this again depending on the type of forces you are applying because your pneumatic tool might have a different delta torques for ranges of settings (e.g. 2 ftlb for under 100 ftlb setting and 5 ftlb for 100-250 ftlb setting etc)... Robert

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