Member postings for Swarf, Mostly!

Hi there, Barry,

You refer to 'missing change gears'. I can sympathise with your enthusiasm to complete the various aspects of your newly acquired lathe but I'm moved to offer a comment on the concept of 'complete set of change gears'.

I wouldn't know nowadays how to discover what change gears Myford supplied with the ML2 at its original sale but it wouldn't have been every number of teeth from 12 to 500! They most likely supplied gears that would cut the most common thread pitches, i.e. Whitworth & BSF. Furthermore, I'd venture to suggest that few owners ever used ALL the gears supplied.

I suggest that your approach should be first to acquire change gear tables for Whit, BSF, maybe BA, ANC, ANF & metric. You could compile those tables for the ML2 leadscrew pitch yourself or find them in the various model engineering handbooks.

Then decide what threads you're likely to want to screw-cut and shop first for those gears, say on eBay and/or at Model Engineering show flea markets. If a large number of ML2 gears shows up at an affordable price then go for it. But in the meantime, don't break your heart because you don't have the change wheels to cut a 3" Whit thread or other rare & exotic threads.

I hope this helps.

Best regards,

Swarf, Mostly.

Mike,

You beat me to it!!!

Best regards,

Swarf, Mostly.

Brian:

If you have a spring balance and a bucket of water, you can determine the specific gravity of the casting. This is an up-to-date version of Archimedes 'eureka' method.

Weigh the casting hanging in air and then weigh it again immersed in water. It will lose the weight of its own volume of water. The specific gravity is equal to the dry weight divided by the difference between the dry & wet weights.

Suppose it weighs 10 kg in air and 8.5 kg immersed in water, then the specific gravity is equal to 10/(10-8.5) ie 10/(1.5) = 6.7 (This example doesn't apply to a real metal - I've just used easy numbers to show the method of calculation.)

Then look up the SG on the internet or in some Tables of Physical Properties. This method will distinguish easily between aluminium and the zinc-based die-casting alloy (aka 'Mazak'. I think pure zinc castings wouldn't often be encountered, Mazak would be more likely.

If you don't have a spring balance, you can use a rod or beam and a counterweight, with bits of string to suspend the beam itself and the casting and counterweight from the beam. You measure the distances from the beam pivot to the casting's string at the balance points dry and in water (keep the counterweight in the same position and move the casting to balance in each case. It's a bit more difficult to explain in a forum like this but by manipulating the two distances, you can calculate the SG.

I hope this helps.

Best regards,

Swarf, Mostly.

Hi there, Paul,

Just a cautionary thought - do you need your lead screw to be Left-hand or Right-hand thread?

And do you need a matching nut?

Best regards,

Swarf, Mostly.