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Making a trigger wheel
myke pocock - 11/4/21 at 04:28 PM

I am converting my Skoda Estelle engine to electronic ignition and am making the trigger wheel. It is 125 mm in diameter. My plan was to drill 36 holes in the correct position and then skim the disc on my lathe to size. Does that sound OK in that will the holes, when skimmed down be sufficiently deep and for that size of wheel what size drill should I use?. Hope that all sounds OK and not to dim!!

gremlin1234 - 11/4/21 at 04:55 PM

I thought trigger wheels had one blank space, so you would only want 35, each spaced 10 degrees apart, and then the one blank

r1_pete - 11/4/21 at 05:33 PM

For the drill size calculate the circumference of the finished wheel, and divide by 72.

It would work, but you'll be spending as much time grinding lathe tools as machining.

Is it worth it when you can buy trigger wheels sub £30?

I like making my own stuff but wouldn't entertain this....

coyoteboy - 11/4/21 at 09:36 PM

You don't need much in the way of tooth depth.

Your teeth don't need to be equal width to the gap, it's the vertical edge of the metal that generates the signal, so you just don't want rampy teeth.

Doing it with a lathe and drills seems like a fair old faff I must admit, but fun if you like tinkering.

JAG - 12/4/21 at 09:29 AM

Try these guys?

http://trigger-wheels.com/store/index.html

myke pocock - 12/4/21 at 10:48 AM

Thanks for the replies folks. I like to make so will go that route besides I can match it as I want to the Skoda crank pulley. The face of that will need skimming anyway so I will also machine it so the ring fits in a rebate.

JAG - 12/4/21 at 12:22 PM

Myke - absolutely. If that's what you like to do then enjoy the making process. Your method sounds relatively simple and should produce a 'wheel' that works (as far as I know anyway!)

However it is worth checking the TriggerWheels site just for reference images etc...

MikeRJ - 12/4/21 at 12:37 PM

quote:
Originally posted by gremlin1234
I thought trigger wheels had one blank space, so you would only want 35, each spaced 10 degrees apart, and then the one blank


He'd need 34 regular sized holes, and then a slot with a length of 3 holes, assuming the metal between the holes is the same as the hole diameter. The "blank" is normally a missing tooth which would be equivalent to an extra hole joined to the holes either side of it in this case.

Bigheppy - 12/4/21 at 03:49 PM

Wrong link can't find the one I was looking for sorry

[Edited on 12/4/21 by Bigheppy]

snapper - 12/4/21 at 08:41 PM

Search Trigger wheel diagram on this forum, I’ve seen one which shows the radius required for the trigger wheel