Angle Calibrated Wrench 3

[drawoh]

Is there such a thing? I may have to design one.

I have a requirement to be able to rotate screw or nut in increments of one degree. This is for optical alignment purposes, although it could be nice for torquing accurate preloads as well.

JHG

 

[amorrison]

My thoughts went immediately to "stepping motor".

Have the electronics set up so that each time you push a button you get a one degree movement. Note that the "base" mount has to be quite rigid rotationally as the incremental movement is so small. Check for backlash.

If the stepper motor does not have one degree steps itself some "gearing" (mechanical or electronic) might be required.

 

[SnTMan]

Don't know if this is suitable or not...

http://buy1.snapon.com/catalog/item...0&group_ID=980&store=snapon-store&dir=catalog

Regards,

Mike

 

[MintJulep]

Manual or power driven?

Like amorrison I also thought of a rotary index table.

Sounds like a challenging concept. Elasticity and stick-slip will be problematic I think.

 

[drawoh]

amorrison and MintJulep,

Definitely, this thing must be manual. Elasticity and stick-slip are exactly what I am worried about.

The Torque Angle Gauge looks interesting.

JHG

 

[desertfox]

Hi drawoh

Just a thought, can you make a graduated dial with degrees to surround the screw and achieve your angular ajustment that way, bit like a toolpost on a lathe.

desertfox

 

[CoryPad]

There are newer torque wrenches with internal gyroscopes that measure angle very precisely.

http://www.asidatamyte.com/en/solutions/assembly/torque-management/

http://www.tic.teac.co.jp/en/products/gyro/gyro.html

http://buy1.snapon.com/catalog/item...group_ID=19918&store=snapon-store&dir=catalog

http://www.crane-electronics.com/iqw.html

 

[MintJulep]

Unfortunately, precisely measuring the angle turned and turning the nut a small and precise amount are not the same.

 

[drawoh]

...
Just a thought, can you make a graduated dial with degrees to surround the screw and achieve your angular ajustment that way, bit like a toolpost on a lathe.

That is what we are doing now. The scale is a piece of cardboard with a cutout for the wrench. The engineer doing the alignments insists that she has a delicate touch developed from years of doing optical alignments. She has no idea of how she is going to train someone else to do this.

If I have to design something, I am going to pay close attention to the rigidity of the wrench, and I am going to look into lubricating the adjustment fasteners. I will try to clamp to the fastener rather than just insert something inside or around it.

Several of the links look very interesting.

JHG

 

[unclesyd]

Could you use something like this 10 turn knob. They also make 100 turn knobs.

http://www.alliedelec.com/search/productdetail.aspx?SKU=6640008

 

[hydtools]

You might look into how an indexing/dividing head is built to precisly divide a circle.

Ted

 

[unclesyd]

Here is a pretty good selection of turn counting dials available.

http://www.surplussales.com/shafthardware/ShaftH-2.html

As I don't know your actual configuration you might want to look at differential screw mechanism.
This is just one of many configurations available.

http://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=1195

 

[desertfox]

Hi drawoh

Well it doesn't sound as though your set up needs to be absolutely accurate and I'm not sure I agree that no one else could do what your present engineer is doing even she had to start somewhere.
Another way of doing your angle measurement would be a known pitch of a thread and use a DTI to measure linear movement as you rotate the thread.

desertfox

 

[drawoh]

desertfox,

I have forwarded some of the catalogue pages noted above to her. I am waiting for a response. I intend to ask about lubricating the screws in the alignment fixtures, which ought to make for better accuracy (and less stability).

I have designed alignable fixtures in the past where I have defined the resolution with respect to a 1/4" movement of the end of a 6" wrench. Is this what you are referring to?

JHG

 

[desertfox]

hi drawoh

Yes I suppose, for a given pitch of thread you can work out the angle turned through for a given linear movent, so I was suggesting putting a dial test indicator at the end of a threaded rod and using the linear movement to achieve the angle required.

desertfox

 

[drawoh]

desertfox,

We are trying to do one degree turns of a wrench on an M5x0.8 nut. That is a 2_micron dial test indicator. The one I just looked at has 0.001" increments.

JHG

 

[desertfox]

Hi drawhoh

What are the tolerances your looking for on this adjustment, ie increments of 1 degree +/- ? also is the linear movement important in terms of the alignment or is it just a means of getting the angle correct? if its just getting the angle correct can you use a larger pitched thread.

desertfox

 

[drawoh]

desertfox,

I am actually not sure. I never get to play with the optics. It would help so much.

JHG

 

[desertfox]

Hi drawoh

Probably stating the obvious (GRIN) but you will probably need some parameters if you need to design a device.
I've had a few jobs like yours where people want somthing but don't really know exactly what they want,"never ending goalposts" is a phrase that comes to mind.

good luck

desertfox

 

[MikeHalloran]

I used to have a distributor-points setting tool that could do 1 degree, easy. It comprised a pin that stuck into the center post of the distributor cap, a sticky gimbal to compensate for non-vertical axes, and a 3"+ diameter magnetic compass. Level the compass, zero the dial, then twist the distributor to the angle you want.

It also had a built-in continuity tester for setting the points, but you don't need that to measure a wrenching angle. You do need to orient the workpiece so the fastener axis is nearly vertical.

... OR use a really fine pitch thread, like you typically find in optics,
... OR tilt the screw and use it to drive a wedge.



Mike Halloran
Pembroke Pines, FL, USA