pres589 (djronnebaum)
pres589 (djronnebaum) PowerDork
6/7/19 4:12 p.m.

Was talking to a friend about broken camera parts and he asked if I needed anything machined.  I don't for the camera we had been discussing but I did wonder about a custom shift knob.  He says he'd love to get something like tht going for the practice of using his lathe and what not. 

Okay, so my thought would be to get a ball knob cut from black delrin.  I don't want metal due to hot and cold discomfort.  A 2" delrin rod isn't expensive and would be a nice size.  What kind of thread insert should be found to make this thing not strip out?  My first thought was a Heli-coil but I don't know if that's really the right thing to use.  Anything better out there?

This is for my Suzuki SX4 with a manual trans.  The reverse lock-out on this car uses a collar that is lifted to engage reverse gear.  The collar goes up into the shifter knob body.  Not a lot of aftermarket options out there saying that they have a knob for this application.  It also seems like a fun project and it would make the car look and feel a little nicer as the stock knob is kind of tired after nearly 130k miles of use.  

So, suggestions on a thread insert for a delrin shift knob?

Stefan
Stefan MegaDork
6/7/19 4:48 p.m.

Timesert I think would work better for that: http://www.timesert.com/

Have them machine the recess into the bottom of the knob for the lockout.

Here are some other potential ideas/options:

https://www.practicalmachinist.com/vb/general/best-thread-inserts-delrin-200590/

 

APEowner
APEowner Dork
6/7/19 4:52 p.m.

He's got a lathe.  He can make one.  Big aggressive threads on the OD and whatever your shift lever needs on the ID.  ID use either brass or Stainless.

Indy-Guy
Indy-Guy UberDork
6/7/19 5:25 p.m.

In reply to pres589 (djronnebaum) :

I'm a design engineer by trade and we've experimented extensively with inserts in plastics for industrial automation.  You want the "key locking insert" trust me.  Available from McMaster Carr in your choice of metric or Standard thread. McMaster Carr link

You screw it into an oversize threaded hole (based on the chart) and then use an insertion tool to drive the four spades into the plastic.  WILL NOT back out.

 

Edit: Note the tapped hole you put into the plastic has an oversize tap drill requirement.  Use the chart to determine drill size of the minor diameter.

 

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