Together forever!


Well not yet, but one set of cases has been drilled and assembled by the shed faires. They were busy while I was on holiday!

The machine in the background is the Denbigh Mill. It has the capacity to machine the bore and face off the throat, which even the Bridgeport won’t manage.

It’s an old machine and in breach of just about every health and safety regulation ever written! (So I tend not to use it). But with common sense and due care ut should do a good job for us.

In parallel I’ve been facing the timing cover, which is quite tricky to mount – but one I have a flat face the rest should be easier. Making 2 complete sets of cases isn’t much extra work, and a spare set will definitely be worth having.

(They’ll make a good ornament/doorstop at least!).

First cut of the cases


The drive side case was first up for fly cutting the mating surface. Bob mounted it to the table and did the faffing about getting it level, but in fairness the casting was pretty straight. I did a dry run of the tool path and when that was complete there was no delaying it. Time for the first cut!

The mighty Bridgeport performed admirably and 20 thou cuts were a breeze. I showed Bob how to start the program and after a couple of goes he was away. We had to take about a quarter off the height, which didn’t take too long at all.

Loads of man glitter kicking around now, so I need to be careful not to get it round the house. Swarf gets everywhere doesn’t it??

On the case!


Weighing in at 26.7kg, one full set of cast engine cases. I weighed them as I wanted to know how much metal gets removed when I machine them. There’s a generous allowance for machining and they’re quite heavy, so hopefully I’ll get to under 25kg.

I had a couple of sets cast and heat treated, so I’ll machine a spare set. The spare can be used for a mockup engine with a barrel for dimensioning the frame. But that’s a way off as there’s plenty of machining to be done. Bob and I will work together on the Bridgeport.

Here we go!

Last few bits


For a while now locating the last few bits from the mights Bristol Hercules engine I need has been playing on my mind. A pair of washers snd circlips for either side of the piston. Not huge items but hugely important and a pain to have to make.

I needn’t have worried. A quick call to Patrick at Maddison 4×4 (who does beautiful restorations of aircraft engines) and very generously they arrived next day! Amazing how the universe works sometimes, thank you Patrick!

Last on the list is the castings, which will be ready for collection on Thursday. Can’t wait!

Back to the Keyboard


While we’re waiting for the cases to be cast and heat treated, I’ve started to write some GCODE for fly cutting the mating faces. With such large components travel on the Y axis is very close to the limits, so a trial run over a set of drawings is a must!

The position of the spindle centre is also critical, and this afternoon I brought it forward. I hadn’t done this before but it was fairly straightforward and with Bob’s assistance now in the right place. Bob remains unconvinced that CNC is better than handle twiddling!

I think we’re going to be ok without resorting to larger machines. Great news as it is VERY close to the limit!

Huge Scissors!


Getting an accurate reading from the press proved difficult, any movement was a combination of everything. All the bending moments of the long bolts, give in the jack and twist of the assembly. Bob wrote off that method and we moved onto plan B.

Plan B. Often this is the most successful of all plans, I do wonder sometimes why anyone bothers with plan A? Would NASB have been more successful than NASA?

Anyway, plan B. Bob made a special tool acting like huge Scissors. In order to twist the flywheels around the crank pin, two mandrels will be fitted into the existing holes opposite the crank pin. The tool inserted between the wheels locate on the two mandrels. When opened or closed using the thread and nuts, the scissors will twist the wheels.

There’s plenty of leverage so it ought to work!