Retapping a hole?

[Tiger]

On my woodlathe, there is a hollow spindle (which is there so you can insert a thin rod to eject a drive spur in case it gets stuck). It measure about 11 mm and I wanted a handwheel attached to the spindle so that I could rotate and stop the lathe by hand. Anyway, although I tried my best to drill and tap a 1/2 inch hole, the hole is slightly off centre and so the handwheel which is now attached to a 60 mm bit of 1/2 threaded rod shows a fair amount of runout. I want to make a combination handwheel/indexing wheel and now I need something a little truer. How should I go about fixing this? All my taps are 1/2 inch or less, although I do have a 5/8 Whit around which is a bit rusty. Maybe there is another solution that does not involve rethreading and anyway to re-thread accurately is difficult as it's hard to keep the tap/drill perfectly square to the spindle.

[old pete]

Hi Tiger,

Take your spindle to a machine shop and get them to bore it out to a size bigger on a lathe or mill and then either tap that hole or make an insert (bush)to get back to 12.4 mm if that's what you want. There's no way you can re--center and re-align that hole you have got now with the gear you describe.

You might just have a few issues getting the spindle removed as well. Make sure you don't damage the spindle thread in the process and when you re-fit it please use new bearings and a new belt!

Cheers Old Pete

[Tiger]

Pete, the spindle looks hard to remove and that's why I didn't get it centred and tapped in a lathe the first time.

Am thinking now that I can just plug the hole with some 1/2 inch thread and then drilling and tapping again but this time with some sort of guide to keep the drill and tap square.

[Woodlee]

It would be much better to bite the bullet and remove the spindle and have the job done properly .
I have been in the engineering trade for along time and no way would I attempt to drill a hole down a shaft with a hand drill ,guide or not ,and expect it to be centered.
I guess the worst you could do is end up having to buy a new spindle for your lathe.

Kev.

[Tiger]

I only drilled 35mm or so into the shaft so the shaft is not damaged. I think on these lathes that the spindle is not easy to remove so I didn't try. All I wanted to do was stick a handwheel on the end.

Is there some way to slightly extend the spindle and then true that extension so the handwheel will run true?

[Woodlee]

Some one assembled the spindle into the lathe in the first place .

I guess if you got a piece of brass bar and had the thread machined on it that you tapped into the shaft and then screwed and loctited it into the shaft.
The brass would need to be over the size of the hand wheel bore how much would depend on the run out of the tapped hole.

Set up a turning rest so you can machine the brass with the lathe under power and a turning chisel down to the size of the hand wheel bore.It would take some careful work and a few sharpenings of the chisel but could be done.
That way at least the hand wheel would be on center to the main spindle.

Kev

[Tiger]

Thanks, Kev. I have always been a bit loathe to play around with the bearings to get to the spindle. Maybe if I saw a video on how to do this and also had the tools I'd have a go at taking off the spindle. At this stage I will go with the other suggestion.

I thought something similar to you about turning true except I was thinking of doing that in Aluminium rather in Brass because I don't have any Brass on hand.