09-12-2014 01:09

asid61

Re: pic: 3 CIM WCD Ball Shifter Dead Axle

How much more machining and where?
What's wrong with the dead axles?

09-12-2014 01:26

Bryce2471

Re: pic: 3 CIM WCD Ball Shifter Dead Axle

The extra machining would go into modifying the vex gear.

I haven't found an elegant way to mount the axle because there is no space for a nut to go behind the back plate.
I also haven't decided what the best way to locate the vex gear along the shaft is.

09-12-2014 01:53

Joey Milia

Re: pic: 3 CIM WCD Ball Shifter Dead Axle

Flush PEM nut or helicoil/other threaded insert?

One way could be use a larger diameter shaft and turn down where there gear is so it's up against a shoulder.

09-12-2014 01:56

R.C.

Re: pic: 3 CIM WCD Ball Shifter Dead Axle

Ditto, I would highly recommend that here.

09-12-2014 02:13

Bryce2471

Re: pic: 3 CIM WCD Ball Shifter Dead Axle

This could work, but tit adds complexity and/or machining time.
Then how would the gear be horizontally located on the bearing?

Thanks for all the advise. Keep it up!

09-12-2014 02:22

Joey Milia

Re: pic: 3 CIM WCD Ball Shifter Dead Axle

A flush mount PEM is pressed into a round hole. It would be just a larger hole than the one for the bolt, no extra machining. (and in one way simpler because you don't have to worry about a nut during assembly)

If the bearing is a proper press fit into a pocket in the gear it'll be fine. It's located by the pocket and there is no side load on the gear to push it off the bearing. This is the same way all the shifting gears are located in a dog shifter.

EDIT: It's a 40 tooth gear correct? If you don't want to machine a pocket get a vex dog gear with the pocket already machined. Vex 40t dog gear part number 217-3417. If the .5 bearing it comes with is too big for the shaft, press it out and replace it with the same OD .375 bearing vex part number 217-2732.

09-12-2014 03:24

Bryce2471

Re: pic: 3 CIM WCD Ball Shifter Dead Axle

Thanks for the suggestions. I have a few questions about the PEM nuts.
If there is no flange, how does it hold the tension force from the bolt?
Where can they be sourced?/Do you have any suggestions?
what are the tolerances like on the press fit?

09-12-2014 03:43

Joey Milia

Re: pic: 3 CIM WCD Ball Shifter Dead Axle

The PEM inserts are pressed into the opposite side of the plate from the bolt, they have a flange but the flush ones are pressed into the material flush which cold forms the material into groves in the nut. They can be sourced from mcmaster here http://www.mcmaster.com/#captive-nuts/=uy130o

GRT has used the standard ones in our GB for the past three years and the flush ones in the 2014 GB. You'll need a hydraulic press if the plates are anodized but if it's just raw aluminum an arbor press should do fine I think.

More info on flush ones here http://www.pemnet.com/fastening_products/pdf/fdata.pdf

and a lot more info on their website http://www.pemnet.com

09-12-2014 03:55

Bryce2471

Re: pic: 3 CIM WCD Ball Shifter Dead Axle

Great. Thanks for the info. I'll be sure to look into it.

09-12-2014 14:02

Chris is me

Re: pic: 3 CIM WCD Ball Shifter Dead Axle

Try tapping one of the plates and using a shoulder bolt. Maybe some spacers between the bolthead and the bearing inner race. That solves both your problems and probably saves you a few more ounces.

I really don't think you need a PEM nut in such a thick plate when you could just tap it.