Took post grinder

P

Pmma-Granville

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hello everyone!
My little old lathe is almost there!
Over the weekend iv been adjusting my spindle alignment, its nice and true now but after chucking up a bit of scrap it's still out of wack by a fair bit! Iv disassembled and cleaned the chuck and it's exactly the same so I'm going to grind the jaws.
The old man who started the company I work for has loaned me his very very old tools post grinder. Will post some pics when iv finished lunch! Anyway he can't find the part for grinding the internal jaws. I very much doubt I'll find an attachment so I suppose I'll be turning one. Iv got loads of silver steel to hand, would that work for what I want?
Does anyone one have any pointers for me?
Thanks!
 
So here it is. Made in London so must be old! The little brown thing with the wires hanging out is its power supply. It plugs into a lamp as a bulb would which is unusual to me.

IMG_0673.JPG
 
It's not at the moment, it has a grinding wheel for the external surfaces of the jaws, it did have an attachment for internal grinding but it has been lost for years, that's the part I have to remake!
 
HI Granville,

The Workshop Practice series has a good book on spindles, that would be a place to start :)

Bear in mind that you're loking for a similar surface speed on the small internal grinding wheel to that of the external wheel - a rule of thumb, as you'll need to use a pair of pulleys to get the required RPM, would be to scale the pulleys as the scale of the wheels - so if you have a 4" external wheel and a 1" internal you could start with a (e.g.) 4" pulley on the motor, a 1" on the internal grinding spindle.

Dave H. (the other one)

P.S. - I'd lose that connector pretty damn quick and put a proper 13A mains plug on it, as it stands it thinks it earths via the bayonet catch bulbholder's er... bayonet - modern lamp sockets don't have an earth there so you'd be using an un-earthed motor...
 
British steel, thanks for that! I didn't even consider the surface cutting speed differences! Will it cause me major problems? Or do you think I'd get away with it? I'm not looking for 100% perfect, just want to get it running pretty much true at a known diameter, then try chucking different dia bars to see if the scrolls worn unevenly. If it is I'll have to look at getting a new chuck as I have no means to fix the scroll!

And thanks for the safety advice! Iv already stuck a proper plug on it, I already look like iv been electrocuted with my Mohican ha ha
 
A good way of double checking your spindle alignment before grinding the jaws of the chuck is to use Rollie's Dad's Method. The method doesn't use the tailstock (which should be set after the headstock spindle is first aligned) and even if your chuck is out of kilter it will give good results, especially if you use a decent test bar.
 
apparently my tailstock is permanently set to centre with a set of 3 pins alligning the top section of tail stock with the bottom which fits snugly on the bed, then to adjust it off centre you disassemble the 2 parts, remove the pins and adjust as necessary.
I did use the rollies dads method to get the spindle aligned though, rather than trusting the tail stock!
 
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