Need a 4BA prop

[Martin Field 1Participant @martinfield1]

Hi, has anyone got a 4BA thread prop in 2 or 3 blades of around 30-35mm diameter for my Chris Craft. I bought an old Sea Hornet on ebay cheap and have turned it into a Chris Craft Special racer with a new deck and hatches. I have now painted it as the rare blue and white scheme and went to check the shaft, only to find that it's 4BA threaded. I can't move it as it's very much part of the hull. I guess I must have been assuming it was M4, but no. 3.5mm diameter shaft with a 4BA thread each end.

If you happen to have a 4BA joint that would be good also.

Cheers,

Martin

[Martin Field 1Participant @martinfield1]

[David Marks 2Participant @davidmarks2]

Martin – There is a possible engineering solution to this problem. You will nee access to a small lathe or know someone that has. Also assuming that the inner prop shaft can be removed from the outer. This will allow you to use a M4 prop on the existing (but adapted) shaft.

Prop End – Obtain a stainless M4 screw of suitable length, remove the head and drill 2.8 mm which is just below the core/minor diameter of the thread. Turn down the 4BA thread on the end of the shaft so that it is a snug fit inside the 2.8 drilled hole. The two can be held together with a minute dab of Cyno e.g. Hafix or similar.

Coupling End – Assuming that you will be using a Huco Coupling (or similar). The inserts for these are available in a number of sizes ( but probably not 4BA), but find one that will allow you to drill & tap 4BA.

[Martin Field 1Participant @martinfield1]

David,

I was thinking along those lines myself. I will have to get a 4BA tap and then drill out the prop and make a thread reducer sleeve, or, as you suggest, a thread increaser to M4. I have 2.5mm drills, or 2.4 (3/32&quot ,but no 2.8.

I'll see what Huco do, but I tend to make my own couplings anyway.

Cheers,

Martin

[David Marks 2Participant @davidmarks2]

Martin

Thanks for the response. Anything in the Taps, Drills, Dies category, then I use Tracy Tools in Torquay.

**LINK**

[Martin Field 1Participant @martinfield1]

David, yes I bought my centre drills from Tracy and a few odd bits and bobs. i tend to use ebay when I can as my wife has it on her machine and does all the Paypal stuff that I don't understand.

Cheers,

Martin

[Charles OatesParticipant @charlesoates31738]

Or you could remove the shaft, and replace the bushes in the tube to use an M4 shaft. Easy fix for a long term solution. Assuming the bushes can be removed, which is usually easy.

Chas

[Trevor Drabble 1Participant @trevordrabble1]

Martin , Suggest you talk with Simon of Prop Shop . Trevor .

[Martin Field 1Participant @martinfield1]

Bushes won't move Charles. I had considered that, but also there isn't room inside the tube for a 4mm shaft.

Trevor, does the Prop Shop sell a variety of threads? Haven't bought a prop from them since I bought a left and right hand pair for my last Riva scratchbuild.

Martin

[Trevor Drabble 1Participant @trevordrabble1]

Martin , Last time I spoke with Simon at the Mobile Marine Models open day he said he taps props to customer requirements . Trevor .

[Martin Field 1Participant @martinfield1]

In that case, I'll give him a shout. Many thanks.

Martin

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