Making up a 3 ball handle

I picked up 3 boxes of blanks (diameter 30, 42 and 75) at the C&A clearance sale. All the nice stuff had too many zeros:~.
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The question was asked how do you make up a 3 ball handle so armed with one of these blanks (which I think is 1040), I set out to find out.
First, rough out the shape
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Then put the angle onto the bits in between. Incidentally, someone was asking about oversize ER40 collets. This is what I am using to hold the stock. They work very nicely.
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Once the angles are in place, whip out the trusty ball turner and start shaping the balls. The largest ball is only half shaped because there is a chuck in the way...
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A close up at this stage. The tool in the ball turner is a piece of broken tap ground on an angle, so it leaves a radius in the corners. I find that if it blends it is harder to clean up with the file than if it is left as a step. After cleaning up with the file and polishing with emery it looks more the part.
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I then parted off and tried shaping the back of the large ball. I first tried packing it with thin card but the chuck did not like that so I ended up making a split bush with a matching taper that would hold the handle firmly enough and concentric enough that I could shape the back end. Even so work was required with the file to get the halves meeting in the middle.
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The split bush also came in handy for holding the handle blank in the mill while machining the flats on the handle and putting the through hole in.
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Easier than I thought it would be but it still took several hours. The steel machined very nicely so I'm glad I got it. The other ball handles I've been making are in the J&S thread as that is what they were made for. Anyone know anyone who needs a 3 ball handle? I have a spare.

Michael

Nice work Michael.

I posted some oversized ER40's in the ebay thread a few weeks back. They are pretty pricey though. Where did yours come from?

Ew

I did manage to find some help at Steve's Workshop. Not a 3 ball handle, but almost.

http://www.steves-workshop.co.uk/tip...allhandles.htm

Dean

I'm with Ew Michael, real nice work. Well done.:2tsup:

Bob.

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Originally Posted by Ueee

I posted some oversized ER40's in the ebay thread a few weeks back. Where did yours come from?

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I can't remember - I think Germany via Ebay as they seem to have lots of ER stuff over there. However, from the look of the boxes that they came in I suspect that they were made a little closer...

I would have liked to stay with ER32 but they stop under an inch diameter which is just that little bit awkward. With the extended range I can hold up to 30mm in the 40's.

Michael

Quote:

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Originally Posted by Michael G

I can't remember - I think Germany via Ebay as they seem to have lots of ER stuff over there. However, from the look of the boxes that they came in I suspect that they were made a little closer...

I would have liked to stay with ER32 but they stop under an inch diameter which is just that little bit awkward. With the extended range I can hold up to 30mm in the 40's.

Michael

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Thanks Michael. At $80 for the 4 plus post from the UK i think i'm better going to ER50. That gets me to 34mm so it covers 1.250" and you only need 12 collets to get the full range from 10-34mm as they cover 2mm each.

Ew

One of the problems with making up a handle like this is putting in a key way for the shaft as usually the shaft diameter is small (1/2" or less) and the key way is proportionally sized - 1/8" is typical.
Typical options for making key ways are a slotter or shaper (including using a lathe) or broaching if you have the broaches small enough. There is another way though that I was taught by a fitter I used to work with.

Once you have the hole in the handle to size, make up a plug in the same material that is a good fit. It doesn't have to be an interference fit but needs to be slop free. Fit the plug to the hole and then using a drill bit the size of the key or less, drill a hole on the plug circumference so that it is half in the plug and half in the handle. Remove the plug and using a small file square the half circle in the handle up until it matches the key.

I've done this once and it does work. The tightness of fit will depend on your filing skills but for an application like this where the torque being transmitted is small any looseness of key fit will just be seen as backlash.

Michael

Very nice work Michael,

It certainly looks classy. Thanks for the tip with small key ways.

Cheers,

Simon

Quote:

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Originally Posted by Michael G

One of the problems with making up a handle like this is putting in a key way for the shaft as usually the shaft diameter is small (1/2" or less) and the key way is proportionally sized - 1/8" is typical.
Typical options for making key ways are a slotter or shaper (including using a lathe) or broaching if you have the broaches small enough. There is another way though that I was taught by a fitter I used to work with.

Once you have the hole in the handle to size, make up a plug in the same material that is a good fit. It doesn't have to be an interference fit but needs to be slop free. Fit the plug to the hole and then using a drill bit the size of the key or less, drill a hole on the plug circumference so that it is half in the plug and half in the handle. Remove the plug and using a small file square the half circle in the handle up until it matches the key.

I've done this once and it does work. The tightness of fit will depend on your filing skills but for an application like this where the torque being transmitted is small any looseness of key fit will just be seen as backlash.

Michael

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P K Douglas located the down feed ball crank on their little shaper with just the round plug, no filing required. Maybe another way if starting from scratch and you aren't equipped with Woodruff key cutters.


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BT

I was thinking about Michael's 3 ball handle while cleaning up in the shed today. It prompted the question to myself, why did they make these in the first place?

The only reason I could come up with (other than they look ace) was so that they were a balanced handle and didn't vibrate to a particular balance point, moving the handle off a desired position.

Is this the reason for the design?

Simon

That could be a reason but they would have to be pretty well balanced to not want to rotate - although if the gibs were snug and there wasn't screw backlash I don't know whether they would rotate anyway.
I suspect that because the handles were counter weighted the effort needed to turn them was more uniform, so a smoother finish. A heavy solid or spoked hand wheel will be very similar as the handle is comparatively light. Some cast hand wheels even had a small additional lump of material opposite the handle to balance out the handle mass.

Michael

Hi Michael,

OK so it basically comes down to style/aesthetics. They look good, like most things built around the time I was born. :cool:

Simon

Quote:

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Originally Posted by simonl

I was thinking about Michael's 3 ball handle while cleaning up in the shed today. It prompted the question to myself, why did they make these in the first place?

The only reason I could come up with (other than they look ace) was so that they were a balanced handle and didn't vibrate to a particular balance point, moving the handle off a desired position.

Is this the reason for the design?

Simon

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One possible reason is that they enable access to the rear for the scale locking ring. The ring-in cross slide wheel on my lathe prevents anyone with fingers more than about 10mm thick from accessing this ring. I can only operate it with pointy nosed pliers, so I intend to wait, if I can! It is the difference between about 320 degree and zero degrees access.

I guess that in essence this means a more compact arrangement or the ability to fit more into the same space. In the case of my lathe the scale ring is quite wide/deep and includes both imperial and metric markings. It is a 3mm pitch shaft so the imperial circle only covers about 0.236" (6mm). I discovered yesterday that the dial shows the full change in diameter, not just the cross slide movement like all the lathes I have used up to now. That will take some getting used to I think.

Dean