The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Lucas, Ignition, Charging, Electrical => Topic started by: RichardL on 23.09. 2020 06:13
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See Subject.
Does it have a name? Can it be bought?
Richard L.
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A little black plastic tit comes with new pattern points usually Richard.
But they are larger than the original little bead and don't go nicely on original points. I don't know if the originals can be got, but think not. When stuck, I usually use a small hole cutter - as for making gaskets - and a piece of sheet rubber (eg old inner tube) to make something that will stay in place.
But I guard preciously the old bits when I can.
That goes for everything to do with the contact breaker assemblies frankly. Pattern parts are poor. Some repairers fit new tungsten tips to old genuine cb parts, true the hole for the pivot post because it wears, and make an oversize post. Which is a lot of very fiddly effort for a gain that is invisible to most people!
The steel backplate assemblies are also out of production at the moment to the best of my knowledge - it changes all the time though. We are not blessed on this front.
And don't start me on a related subject - HT pick-ups of the screw-on variety for late K2Fs and K2FCs. Excellent ones were available - but the only parts widely available now are not good. At 50°C+, it can often take almost 100 extra mag rpm to get sparks to Lucas spec with them fitted, compared to a good original pair. Very not good.
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The little nylon button is a tight press fit in the genuine Lucas points, though they are often missing. It can be quite a struggle to get one back in place, they are not designed to be removed, the recess in the moving contact is larger at the bottom than at the top for the button, so they cannot be reversed for use in a clockwise assembly.
I dont think they are, or ever were, available as a spare. All the small bits for the points assemblies seemed to be supplied together in what was described as a magneto "Sundries" kit, but having had a few of these "Sundries" they did not include the button.
The repro points with the black button have recesses the same size and the btton is not a toght fit, allowing it to be used for either anticlockwise or clockwise assemblies.
If you can find new old stock Lucas at a reasonable price they are worth buying.
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Thanks, guys. As I suspected regarding availabilty. Still wonder if it has an official name. Good thing they're not so small as to be easily lost on the garage floor. Seems like a candidate for 3D printing on a printer of appropriate resolution. Very interesting about the tapered recess.
Richard L.
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Well, I suppose 3D printing is probably not the best method. Jeweler's lathe?
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Not a tapered recess. The hole for the pivot is constant diameter. The holes in the steel at either end are of different diameter, small for the button and larger at the base of the pivot post.
The photo shows 2 x Lucas anticlockwise moving contacts, left hand one shows large hole to go over the base of the pillar and the right hand one shows the smaller hole for the button.
The repro points with the black button has same sized holes so it can be used for anticlock and clock applications.
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I turn the button from P.V.C. stock and with a little file work they work quite well.
I have seen them made from aluminium also.
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Not a tapered recess.
Thanks, Julian, I'm impressed that you understood my misunderstanding. Are you a therapist in your day job?
Richard L.