Monday, 25 November 2013

another odd one (part 1)

Well, this must be the season of oddities.

This project is a 1:35 Tiger tank barrel. A friend of mine is assembling the model, and found that the kit contents included a badly warped barrel casting. Rather than do the sensible thing and request a replacement from the manufacturer, I said I'd give it a shot.

I found a piece of brass rod of suitable diameter and cut it a little over length with a hacksaw. The saw has a cobalt blade which will even handle O-1 drill rod (my dream shop includes a metal-cutting bandsaw).

Brass might be a little heavy for this application, but I really want to get better acquainted with its idiosyncrasies. A bit of PVC or ABS would work just as well.

Thanks to the bored-out spindle, the 3/8" diameter rod slipped right into the headstock for facing and turning the small diameter at the breech end. I'm using a brazed carbide tool that produces a good finish at about 1300 RPM.

The barrel is tapered, so the tailstock will have to be offset to achieve this. Also, the muzzle brake is a fairly complex shape, but that portion of the casting seems in good condition. I will simply remove the cast muzzle brake, drill out the end and press it on to the new barrel.

I'd like to do the taper turning between centres, so I've chopped off a piece of drill rod and fitted it into one of the collets. Using the carbide tool in the topslide set at 30ยบ, I turned the drill rod into a dead centre. I have fitted the spring loaded, ball-bearing live centre into the tailstock. It remains to make a small dog for the headstock to drive the barrel, and calculate the tailstock offset to create the taper AFTER I've turned the small diameter for the brake at the muzzle end.

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