As I'm going to build this i thought I might just as well document it as it may be of interest to others. I decided to start with the body casting as it is the trickiest then the rest must be easy! However, I've hit a snag before I've even started and that is how to hold the casting for machining. If you look at item 2 on the drawing the left hand face needs to be machined and a 2" register bored with a 3/8" tapped hole right through. I can't hold it in a chuck because of the spigot on the rhs is too large to allow the casting to sit in the jaws of the chuck.

I could hold the casting in the chuck and drill and tap 3/8" from the spigot side of the casting and then mount it on a threaded mandrel, then carrying out the various machining in the lathe but I'm concerned as whether a 4" diameter casting hanging on a 3/8" mandrel is pushing my luck a it too far. It can be seen in the top left of the drawing is a suggested method of holding the casting for machining the spigot, but that's not much help for what I'm trying to do. Any advice and suggestions will be most welcome. Phil

I hope this photo shows how the spigot is too large to allow the casting to be held in the chuck jaws.

The photo is a posed shot with the tool holder holding the casting against the chuck.

I am currently thinking that when this turret kit was designed and offered for sale very few ME workshops would have had milling machines and large lathes, so there must be a way of doing it using a typical 3 1/2" lathe but at the moment I can't see it, so any help very much appreciated.

Phil

Oh wow, what a plethora of suggestions I'm not sure where to begin. I'm going to spend some time with my tablet in the workshop running through these ideas to decide which way forward. I had thought that I could do the problem machining on my vertical mill with a boring head but the set up again is problematic. Initially I liked Frank's idea of a purpose made mdf packing piece but the problem here is any kind of clamp to secure the casting will prevent the machining from taking place.

I also thought that a chucking spigot would be a simple solution but obviously not much help to me with this particular casting, I don't believe that this kit is still made l bought it at a club auction about 30 years ago and all I know about it is what is printed on the drawing ie. designed by Sparey in conjunction with the Model Maker magazine and I believe that that magazine is long since defunct, but maybe someone here has more information on that.

I will be keeping this going as a build thread but please don't expect rapid updates as my workshop time is limited and I never work that quickly at the best of times.

Phil

Edited By Philip Rowe on 05/02/2021 12:19:06

So the next stage with this turret is machining the rotating casting, a great deal of head scratching and thought was required to enable me to machine this and maintain concentricity where it matters. The raw casting was mounted in the three jaw chuck using the outside jaws and the outer face of the casting was machined to size, the 20 degree tapered section was a minor problem as swinging the top slide round to achieve the angle meant the feed handle was fouling on the cross slide, so I had to remove the handle and replacing it with a convenient piece of scrap to enable me to rotate the feed screw. The part of the casting underneath the jaws that can't be machined at this stage will be removed later as concentricity is not important here as this area is just knurled to provide a finger grip.

The next stage was reasonably easy, the casting was drilled about 10mm dia and then opened out to finished size with a boring bar, there was a lot of spring in the bar so multiple passes at each setting were required before finishing with a 1/2" reamer.

The piece of paper towel has a weak magnet behind it to collect the worst of the iron dust but l won't be sorry when all the machining of the castings is finished it really is messy stuff!

Phil

Here you can see the rotating casting mounted on the rotary table on the drilling machine to have the six detent holes drilled. If anyone is wondering, the cords each side of the drill column is my crude method of counterbalancing the weight of the drill table. Its something that I rigged up in a hurry probably 30 + years ago and have never got round to improving but as they say "if it ain't broke don't fix it ". As you can probably imagine the drill table, rotary table and the casting being drilled all cast iron is quite a weighty lump to manoeuvre around, so I was quite glad of the counterbalance no matter what it looks like.