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Building a Redwing

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Late in 2020 or early 2021 I purchased a partial set of Redwing castings from the guy who used to import them into the UK and also build them.  He had made a start on the main casting having skimmed the base, faced the cylinder head end, and machined the main bearing platforms.  There were a couple of crankshafts, a used machined piston and a partially machined flywheel and partially machined carburettor.

At the time I had just finished a couple of Alyn Foundry engines and was working on a Stuart 10V.  Covid and my Dad passing (just short of his 100th) and various other issues then got in the way and I have finally decided I need to get back in the workshop and try and do something useful.  Although I have another 12 or so sets of castings on the waiting pile I decided to try and do the Redwing.

So this week I started to look at the main casting.  Checking it on the marking out table, having removed a few burrs/bruises from the base showed the bore to be parallel to the base and the big end platforms at the correct 25 degrees.  Checking the height of the bearing platforms I found that the main bearing centre would not be quite in the middle so I need to take a small skim of the platform to move it.

Started by mounting the casting upside down in the vice on previously machined area on top of water hopper.  Several layers of thick card either side of the casting, clamp on top of the cylinder and a machinist jack under the free end of the casting.  A bit of tapping and jiggling about and all was square.  At this point in time all I wished to machine was the recess in the base for the steel forming the underside of the fuel tank, two dowel holes for lining casting up on a jig plate, 2-56UNC tapped holes for screws to hold the fuel tank base, main fixing holes for the casting and associated counterbore, and the tapped hole for the dummy cylinder water drain tap.

I had to borrow a 3/8" two flute slot mill as for some unknown reason I did not have one.  Before starting machining I had done a drawing with all dimensions/moves calculated for the recess , main holes, tapped holes and dowels.  I had also marked direction of table handles so as not to cock up.  So pleased I have DRO on this mill. All went well, even the 2-56 tapping.  I did not have the requisite 1.85mm tap so stayed with 1.8mm and went very slowly, 1/2 turn forward then half turn back.

I had ordered some .8mm stainless for the fuel tank base and carefully cut and shaped it and drilled holes.  Next step is to modify a counterbore to use as reverse counterbore.

This will be a very steady and slow build.  It is good to get back into the workshop and actually make something.


I'll be watching your build closely as I've had a fantasy about purchasing the casting kit from PMR and attempting it.

Great start!  Keep up the good work!


Alyn Foundry:
Great to read you’re “ back in the saddle “ so to speak Colin.

Are these the castings that JB used to market? If yes, he approached me many years ago to take on the franchise.

Did you get the gears and governor parts? If memory serves you had to get them directly from the States?

 :cheers:  Graham.


Hope you and family are keeping well.

I would need to search my Ebay/Paypal invoices to find the note of the guys name, but certainly he was the guy that used to import them.

There are a lot of little brass castings but I have not related these to the plans as yet.  There were no gears, so I am either going to have to make my own, get them made or buy them if available (possible Forest Classics or Engineers Emporium).  Never made gears so could be interesting.  My mate Tom has lots of gear cutters as he is into clocks so he may possibly have the correct cutters.


They look to be bog standard 24DP gear so should not be hard to cut or find, someone like HPC will have them, you may just need to reduce the thickness and adjust the bore. The presure angle is not critical so 20pa will do so long as both gears are the same.

Could even change to MOD1 gears which are cheaper to buy, change the 1.5" distance from crank to cam gear pivot to 37,5mm and use 25T & 50T


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