Brass Ball drill & Tap fixture

[bobs7-62steamair]

Here is a fixture I have built and used successfully to drill & Tap a .500 inch diameter Brass Ball used in Fly ball Governor construction. I ball end milled a cavity in a piece of 1" CRS and drilled & Tapped 4 holding screws at 90 degrees. You need to ball mill the cavity about .030 to .050 inch deeper than the mid point on the ball to successfully hold it in the fixture. The brass screws have a portion of the tip turned down to minor diameter and smoothed to grip the ball without scaring or damage. Locking nuts are provided to maintain the pressure on the ball during turning. Don't need a lots of tightening to hold the ball in place for drill and tapping, of course you can over do here and scar the brass with a brass screw if excess pressure is applied. Tap was a 5-40 tapped about .400 deep. Balls came out without a scratch!

 

[kvom]

When I needed to drill balls for my last project's governor I found I could just hold them in the chuck jaws. But as you said, I didn't have to tighten the jaws much at all for drilling and tapping.

 

[Blogwitch]

Very nice, but a bit OTT for what needs to be done.

I drill softened ball bearings by just holding them in either a 3 or 4 jaw self centring chuck, but for tricky bits like glass balls, I tend to use my collet chuck, a better control of pressure on the part.

John

 

[Nick Hulme]

I too just use a Collet Chuck ;-)

 

[goldstar31]

It's nice to see a catspaw chuck again and it is still is a useful( and cheap) way to hold irregular pieces for machining.

Laughingly to a younger generation- it was forerunner to both the self centring and independent chucks..

And then some poor sad benighted soul called Keats 'Invented' a variation called the Keats plate.

Oh dear, oh dear!

Norm

 

[Blogwitch]

There is very little new in this game Norman.

I read lots of old books dating to the turn of the 20th century and just a little later, and see things today that are just updated versions of tooling or techniques.

Most of this very good information and techniques have been lost over time. If only people would do a little more readin, most of the questions asked on here could be eliminated.

John

 

[MRA]

If only people would do a little more reading, most of the questions asked on here could be eliminated.

In a previous life, I used to teach engineering. I ended up feeling that most of the role of the lecturer was to give the students confidence that, given a little application, their effort would be rewarded and that they'd grow in competence. Some of that involved choosing reading for them; something I thought was at the right level, with perhaps some extra guidance around sticky bits or outright errors in the text. A lot of what I recommended was written a long time ago, although most is still in print. That's what I get from forums like this - 'I've done this before, and I found xxx useful. Watch out for the errors in yyy drawing'.

 

[mcostello]

I hope people come here for information. The way the path to the answers gets sometimes wanders.. This is only the stepping stone but the journey is most interesting.

 

[Blogwitch]

Don't get the wrong idea, I have to make one like Bobs for my lathe.

Just that I will be fitting it on the other end of the spindle, just like gunsmiths do to keep the material running straight while it goes through the spindle to the chuck, which is also usually a cat chuck, to get the barrel perfectly on centre.
I just don't like wobbly material sticking out the back of my spindle.


John

 

[nel2lar]

John
I can not agree with you more about stock sticking out the wrong end of a lathe. I seen a video on U Tube about that: A CNC operator was starting a job, everything set to go and when he started the machine it started whipping and moving that big machine all over before the operator could shut it down. The end sticking out looked like a pretzel. I have seen videos where the use a weighted loose fitting steady sitting on the floor to prevent excessive whipping.
We must think safety any time we do thing differently or out of the norm.
Nelson

 

[goldstar31]

I agree with Nelson in that there is a harmonic situation which really needs another fixed steady - at the wrong end of the lathe.
Presently, I have a notional 20mm bit of round in the 20mm spindle on my little Sieg C4 and the loose end is only sticking out about 5 inches-- and that is whipping.

I'd seriously forgotten and that is probably the answer why my bit of EN8 is exhibiting a ridgy finish.

I'd guessed that it was a set of 'shot' bearings in my recently purchased secondhand machine.

So my next job is to try a cob end of 20mm stuff-- and see.

Thanks

Norman

 

[Wizard69]

Depending upon spindle and stock size something as simple as a cork can do wonders to keep bar from whipping. If you are in a hurry there are a number of ways to keep the bar from whipping but in the end a far end mounted chuck or cats head is the ultimate solution.

 

[mortimer]

The Dean .Smith& Grace lathes had an attachment at the wrong end where it had 3 equally spaced jacking bolts to steady long shafts and stop them whipping but you kept far away. Any loose clothing is instantly removed

 

[butch wright]

Here is a fixture I have built and used successfully to drill & Tap a .500 inch diameter Brass Ball used in Fly ball Governor construction. I ball end milled a cavity in a piece of 1" CRS and drilled & Tapped 4 holding screws at 90 degrees. You need to ball mill the cavity about .030 to .050 inch deeper than the mid point on the ball to successfully hold it in the fixture. The brass screws have a portion of the tip turned down to minor diameter and smoothed to grip the ball without scaring or damage. Locking nuts are provided to maintain the pressure on the ball during turning. Don't need a lots of tightening to hold the ball in place for drill and tapping, of course you can over do here and scar the brass with a brass screw if excess pressure is applied. Tap was a 5-40 tapped about .400 deep. Balls came out without a scratch!

View attachment 94737

Dat goooood.