Trip reset knob.

utopia · 13-06-2017, 11:10 PM

Hopefully leaving the humour behind for a moment ...
I peered down the hole in mine but couldn't see a screw.
So I poked around with a small Philips screwdriver and found that something had crawled down the hole and pupated.

Now that I've removed it and had a closer look, I can see that my second method wouldn't work.
And neither would the broach idea.
Nasher's would ... though I never feel entirely confident in glues for plastic. Maybe that plastic weld powder stuff would be another option, building the shape around a dummy shaft, as per my solder idea.
And the solder method (bizarrely) seems to more feasible than I had expected.

I had a go at measuring the thread.
Counting the threads over the 6mm length as best I could (scratching with a pin and counting the clicks), I couldn't get closer than 13 to 15 clicks.
Meaning a measured pitch of between 0.40 and 0.46mm
There are both coarse and fine M2 threads listed in my tables and frustratingly they are 0.40 and 0.45mm pitch.
Then it gets really weird because the one listed as metric fine has the coarser, 0.45mm pitch.
It doesn't look like a misprint, given the pitches listed either side of that diameter .. and the metric coarse table lists the finer pitch, seemingly by way of confirmation.
So there's a potential stumbling block then !!

The diameter of my screw is about 0.076", which seems like a likely clearance on 2mm.
8BA is rather bigger at 0.086" dia, so I don't think its that .. even though 8BA is about 0.43mm pitch (59 tpi as Uncle Duke said), which lies between the two metric ones.

So I'd say its M2, but goodness knows whether its coarse (ie finer) or fine (ie coarser).

Dukedesmo's info suggests that it might be the finer, 0.40mm pitch.
So metric-coarse then ?
Whatever you try, I would recommend not forcing it if it seems tight.

13-06-2017, 11:10 PM	#10
utopia No turn left unstoned Join Date: Jun 2010 Location: leicester Bike: M750 Posts: 4,546	Hopefully leaving the humour behind for a moment ... I peered down the hole in mine but couldn't see a screw. So I poked around with a small Philips screwdriver and found that something had crawled down the hole and pupated. Now that I've removed it and had a closer look, I can see that my second method wouldn't work. And neither would the broach idea. Nasher's would ... though I never feel entirely confident in glues for plastic. Maybe that plastic weld powder stuff would be another option, building the shape around a dummy shaft, as per my solder idea. And the solder method (bizarrely) seems to more feasible than I had expected. I had a go at measuring the thread. Counting the threads over the 6mm length as best I could (scratching with a pin and counting the clicks), I couldn't get closer than 13 to 15 clicks. Meaning a measured pitch of between 0.40 and 0.46mm There are both coarse and fine M2 threads listed in my tables and frustratingly they are 0.40 and 0.45mm pitch. Then it gets really weird because the one listed as metric fine has the coarser, 0.45mm pitch. It doesn't look like a misprint, given the pitches listed either side of that diameter .. and the metric coarse table lists the finer pitch, seemingly by way of confirmation. So there's a potential stumbling block then !! The diameter of my screw is about 0.076", which seems like a likely clearance on 2mm. 8BA is rather bigger at 0.086" dia, so I don't think its that .. even though 8BA is about 0.43mm pitch (59 tpi as Uncle Duke said), which lies between the two metric ones. So I'd say its M2, but goodness knows whether its coarse (ie finer) or fine (ie coarser). Dukedesmo's info suggests that it might be the finer, 0.40mm pitch. So metric-coarse then ? Whatever you try, I would recommend not forcing it if it seems tight.