Trip reset knob.

[utopia]

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.

[Dirty]

Originally Posted by utopia

Hopefully leaving the humour behind for a moment ...
I peered down the hole in mine but couldn't see a screw.

.

[slob]

https://www.amazon.co.uk/Bond-Strong...=q+bond+powder

...or If I can borrow one to make an accurate computer model, 3D printing should work fine for a low stress part.

[Nasher]

The screw is listed as M2 x 6, but no mention of pitch.
https://www.ducatiomaha.com/products/77640021a

As Slob has said, twice now, a 3D print in ABS of the Knob would be perfect.

Unfortunately I'm not good enough with AutoCAD to do the model myself.

Nasher

[Dukedesmo]

M2 x 6, I have a box of them as one of the products I supply uses them to fix guide plates. I'm not sure what is fine/coarse etc. in terms of pitch but would imagine it is the more common variety.

I got the 0.4mm pitch from a die that I have which is an M2 x 0.4 and the screw runs through it perfectly.

[Dukedesmo]

Originally Posted by Dirty

.

I'd be more worried about the thing that had crawled down the hole and pupated...

[Dukedesmo]

Sorry, finding it hard to to resist the knob gags.

[Mr Gazza]

Such an important little screw!

I clearly mistook my screws for M2 when they are actually M3 as Dukedesmo correctly guessed... So now we have the correct screw size and multiple sources.

The 8BA screw I tried, does fit and will work if all you can find is an 8BA (as in my case).
It's not quite right, close enough though.... You'd never know.

I do agree with Slob that 3D printing would be ideal for this part.
I mate of mine happens to be a 3D cad expert and has drawn for government and military projects. He's retired now but as aeromodelling buddies, a Solidworks model would be no problem.

I am very tempted to make a temporary one as discussed above, and use that while the replacement that Dukedesmo is so very kindly sending, is being CADed up.

No idea where to get 3D printing done at the mo, but a minor obstacle once we have a CAD model.

Once again totally impressed at the way this club latches onto a small but significant problem and solves it with a few clicks and a lot of good will..

Probably wrong of me to suggest making it sticky, given the other content?..

[Darren69]

Cue sticky knob gags!

[Dukedesmo]

To add if anyone's lost the screw and wants a replacement I'm happy to pop a couple in the post.

They are of course commercially available but you probably can't buy just the one (other than from the German parts supplier listed earlier) IIRC I've bought them in packs of 100.

[Nasher]

Ah, the Glory of Forums.

A bunch of Guys sat around talking Knobs.

Did I mention that I'm sure my Knob must be slightly bigger than anyone else's, which is why it's held in by friction with the rubber alone.

Nasher

[utopia]

On the subject of Gary making his own, I wonder...
Willy .... or won't he ?

It would probably add a certain sense of satisfaction if he could pull it off all by himself.

[Nasher]

Yep. he might pull it off by himself - touch wood.

[Mr Gazza]

I'll just please myself if it's all the same....

After a bit of a rummage and fiddle, I managed to come up with an easy quick fix. Just enough to reset the trip a few times while my mate is CADing up the new winder.

I decided that's the way to go while the iron is hot. Then I can beam the drawings to anywhere on the planet, to be created on any kitchen table in minutes....It's Star Trek come true really!

Here's what I bodged with some model control line fittings. I assume they would be 8BA.. And believe it or not that's a nyloc nut... Must be made by Pixies!

[Nasher]

Originally Posted by Mr Gazza

It's Star Trek come true really!

I've called our 3D printer at work 'The Replicator' since we first brought it.
Most people look at me without a clue what I'm on about.

Originally Posted by Mr Gazza

Here's what I bodged with some model control line fittings.

Nice one.

Note, not a single Knob joke in this post.

Nasher