1934-1940 Horn

[ammorest]

Joe, that drill guide would be great! Thanks. Now I have to get a face. I see Greer doesn't have them. Any ideas?
Dave

[FLFD7]

Dave,

I went on line and it looks like Kiwi has the face.

Here is the updated drill guide, I added a notch for a 1/4” screw to help with the alignment.

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I’ll get your info after I print them.

Joe

[ammorest]

Thanks again, Joe. Worked on two horns today. Got them to blow. Two different tones, one high and one low. Might play around with the adjustments to make them sound better.
Dave

[FLFD7]

Dave and Paul I sent you messages….

[FLFD7]

Since we have had this conversation about converting a car Auto Lite horn to an Indian face horn I went through with it and figured I’d document it for Dave and Paul and whomever else is going to give it a try. This is going to be a bunch of posts with tons of photos and me blabbering about what I did .

We left off when I had drilled and tapped the car horn for the new studs and made some sleeves to mimic the original parts. First a coat of paint.

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All the original horns I see aren’t a glossy black, so I used a semi gloss rattle can.

Original horns have a paper gasket between the body and the vibrating disk, I was lucky and salvaged an original.

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And then the disk

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Again on the original there is another paper gasket and then the horn face, but I noticed on the Kiwi repop horn face there is pronounced step on the back that didn’t play well with the vibrating disk (I found out by trial and error), so I printed out a thicker “gasket” to prevent the binding that was happening. I guess you can make a thicker paper gasket as well.

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continued next post….

[FLFD7]

Continuing on….

Here you can see the step on the back of the horn face

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and how the spacer I printed stands proud of it

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I didn’t take pictures of the drilling and tapping the holes, the Kiwi face comes blank, you gotta drill your own holes. I made up a fixture for that.

This part maybe a little controversial, but follow my reasoning. The original horn faces used 1/4-28 fillister head screws, with a special reduced head diameter (.325). This is because there is no room for the standard 1/4” fillister head (.415 dia). I’ve seen horns using socket head screws, they are .370 dia, they do work but don’t look right, if you’re a purist. What my father had used, and what I went with, are 12-24 fillister screws, the head diameter is .345 and they look the part. Also, while you can get the correct screws from Greers, they are almost $4 a piece, so $24 just for the screws. I got a box of 100 of the 12-24 screws from McMaster for like $9. No brainer. Of course, if you have an original face already drilled and tapped, bite the bullet and get the correct screws, but since we are drilling our own make it whatever you need.

Some pictures of the screws

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Thats an original screw, the 1/4-28 shcs, and the 12-24 fillister head.

Ok, everything lined up and repop face on.

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to be continued….

[FLFD7]

….and we’re back

Here is the backside of the horn, you can see how tight the screw head clearance is

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Now we can start putting the rubber cushions on. I must note here that the size and thickness of the rubber cushions is important, the stack up height must be just so for the back cover to fit properly. Rubber too thick and the cover not going to seat right, too thin and the horn will wobble around too much. So, to me, it’s worth it to get the rubber cushions from Greer, even at $16 a set. We do heed to modify the first set of rubbers however. They are meant to fit like original studs, which are 1/4” dia, so that’s what the holes in the rubber are. But I’m using a jam nut to hold my screws (fake studs) in place. So I need to enlarge those 1/4” holes to 3/8”.

Let’s face it, it’s tough to cut rubber. What I have found to work well are forstner bits meant for woodworking. The problem is holding the rubber in place, lucky me I got access to a 3d printer…

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You can see the 3/8” bit, and the modified rubber cushions. Only the first pair of cushions need to be modified!

Now it’s a tight squeeze but the first pair of cushions goes on. I used a little screwdriver to help get the rubber around the jam nut.

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Now I put my 1/4” dia sleeves on..

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and we can continue stacking.

yes there’s more….

[FLFD7]

Moving on….

Ok, now I’m going to look like a cheapskate, but here goes. Greers makes excellent parts (in my experience), but let’s face it they can be expensive. The rubber cushions are held in place with metal cups, and Greers has really nice ones, but they are like $45 a set. I know manufacturing, you got to make tooling, you got to make and stock so many, I get it. But my grandfather was Dutch….and the Dutch known to be thrifty…and I do have a 3d printer, so $45 vs next to nothing..

This is what I came up with..

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Again, don’t get me wrong, Greer stuff excellent, and if you doing that perfect restoration go for it ( although his are cad plated and all originals I see are painted black?). But this is a part literally nobody will see sandwiched between rubber cushions and a cover. Grandpa would be proud…

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The first cover or cup is the “big hole”. This has a large thru diameter to allow the horn to wiggle around as it vibrates. This is also what captures the mounting brackets on the two flanges.

Again I turn to my 3d printer and make some substitute mounting brackets, for spacing only. The Scout brackets are different then the Chief / 4 brackets, so rather then commit to using for one or the other I made some fake brackets ( same size ), and I made them a different color so it was obvious not the real deal.

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Here they are compared to a real brackets.

So brackets go on and then the final pair of cushions, not modified, with the 1:4” holes

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Then the last cover or cup gets put on. Now these covers sit on the shoulder of the studs, or in our case on the 1/4” dia sleeve around out mounting screws. This captures the rubber cushions and therefore the mounting brackets, and the inside of the flat back cover sits on the backs of the cups. Again, the spacing is important.

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Yep, one more post…

[FLFD7]

Ok, we’re rounding the final turn….

Ready for the cover

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Some nice shake proof washers and acorn nuts and we done baby….

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And there is my first converted horn.

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Hope this was helpful to somebody out there. Good luck with your projects…