Headstock casting

(Chris Small) #1

Evening all! :slight_smile:

I’ve been working on a pattern for a headstock casting. I tried to ram up a mould a few days ago and it didn’t fare so well. I attempted to modify the pattern, this morning, to add a bit more draft - the slight inclination to the surface to facilitate withdrawal of the pattern from the mould, but that, too failed. I persevered with the pattern as it was originally constructed from marine-grade plywood.

The pattern required a lot of metal. More than I am comfortable working with by myself. The thing about hot metal is that it weighs a lot more than cold metal. (Not really - it’s just that you can’t put it down and if it’s weighty, then you don’t really want to be changing your mind mid pour or mid heat). And if things go wrong, the consequences can - and usually are disastrous for the person on the other end of the crucible.

I used a stainless pot, once again, for a crucible and have just about concluded that I want a proper crucible, and tools, because I’m going to end up hurting myself, or worse, others. The pot I was using, today, had some 10kg of metal and it cracked while I was trying to lift it from the furnace. Not good! In spite of that, I had a bit if a mess but a reasonably successful casting. (See attached pics). I won’t try to re-do it because it’s a lot of effort and risk for a result that might not be any better than the current casting.

(Stephen Davies) #2

Impressive making there Chris. Is this a Gingery inspired design?

(Chris Small) #3

Thanks Steven.:slight_smile:

I started building a Gingery lathe in 2014/02 - but I found a few design limitations and my work was just not accurate enough. The bed was prone to tortional distortion and it was a general failure. Since then, I’ve done some more reading, rebuilt an old cast-iron wood lathe as an interlude and resumed work on a new design for a metal lathe. It draws on some of Gingery’s design but also draws heavily on Romig, Yeomans and the Open Source Concrete lathe project. The design is, to some extent, my own, but with some very obvious borrowings from the various authors. It’s likely that it will be a means to an end - a better lathe:smiley:

And, in the spirit of what I think MHV is about, I’d like to contribute to the organisation (and, maybe save others getting hurt, too;) I was more than a little worried, today, during this pour.

(Chris Small) #4

I’ve done a little work on the head-stock to drill it out, ready for boring. I’ve also slit the bearing clamps and drilled them ready for tapping. I still have a lot of work to do on the base of the thing and might have to end up shimming it with some brass shims. It needs to traverse part of the length of the ways during the boring operation but once this is complete, it’ll never have to move again. I started building this thing in January. Once the headstock is complete, progress should increase. Ah! While I think of it, the boring bar looks crooked. The assembly is temporarily clamped while I work out placement of each pulley, the motor assembly and the paths of travel of the carriage and cross-slide relative to the various clamps and things.