Topic: Re tapping a shift knob

[Dylan780]

So the shift knob I have been looking for has finally popped up for sale but is m10x1.5 thread pattern. Would I be able to either drill it out and insert a 12x1.25 piece or drill and tap the knob itself to be 12x1.25?

I believe that the knob is delrin.

[funk32]

Picture of said knob? Does it already have an insert with metal threads?

[F1Eng]

So the shift knob I have been looking for has finally popped up for sale but is m10x1.5 thread pattern. Would I be able to either drill it out and insert a 12x1.25 piece or drill and tap the knob itself to be 12x1.25?

I believe that the knob is delrin.

I don't think you'd be able to go from M10 to M12 without the 'valleys' of the M10 interfering with the new 'peaks' of the M12 (because of the pitch difference.) but you could and tap the knob for an M14 thread and use a threaded insert to get back to M12. Provided it has enough meat. Mcmaster Carr has keenserts or slotted inserts that would work, don't use heli-coils because they need a dedicated tap. (bs lol)

[Dylan780]

It doesn't specify whether it comes with the insert or not but from looking at the photo they provide it looks like it doesn't. I have already ordered it with hopes I can make it work so I guess once it actually arrives it will be easier to figure out if it can be tapped or not.

Anyways here is a photo of the knob from the internet:

[Jay89]

I'm thinking time serts or helicoils

[Mr Crowley]

Major Diameter for M10 x 1.50 should be approx 10mm minus a fraction of a mm. That's not technically correct I know but it will do for this example.

Tap drill size for a M12 x 1.25 bore is 10.80mm.

Theoretically you should have 0.80mm before the valleys from the old thread started to interfere with the peaks from new threads. You should be able to drill out old threads with a 10.80mm drill bit clearing all M10 threads, then run your M12x 1.25 tap. However, it's late for me and I may not be thinking clearly. Bed time.

[F1Eng]

Major Diameter for M10 x 1.50 should be approx 10mm minus a fraction of a mm. That's not technically correct I know but it will do for this example.

Tap drill size for a M12 x 1.25 bore is 10.80mm.

Theoretically you should have 0.80mm before the valleys from the old thread started to interfere with the peaks from new threads. You should be able to drill out old threads with a 10.80mm drill bit clearing all M10 threads, then run your M12x 1.25 tap. However, it's late for me and I may not be thinking clearly. Bed time.

spot on.