We have a 5X20 Chipmaster at the museum where I volunteer. It has been a
lovely little machine,and is very solid and ridgid for its size. We are
having a problem with it at the present though, and would appreciate any
information about the variable speed drive. It is one of those double cone
arrangements with hardened steel balls between them. Tilting the axis if the
balls makes the effective radius of the drive and driven cones change, thus
varying the output speed. Our problem is that it will no longer change speed
smoothly from hight to low speed or vise versa.
Has anyone else had this experience? I suspect that the 5 balls are worn
slightly, and I'm considering swapping them upside down to get the load onto
a previously unused section of the ball.
Is this reasonable, or should we just replace it with a shaft and a variable
frequency drive?

Grumpy wrote:

Has anyone else had this experience? I suspect that the 5 balls are worn
slightly, and I'm considering swapping them upside down to get the load onto
a previously unused section of the ball.
Is this reasonable, or should we just replace it with a shaft and a variable
frequency drive?

I never owned one, but have heard that the variable ratio drive is the
Achille's heel of an otherwise excellent lathe.

Jordan

On Wed, 6 Jan 2010 17:57:05 +1100, "Grumpy"
wrote:

We have a 5X20 Chipmaster at the museum where I volunteer. It has been a
lovely little machine,and is very solid and ridgid for its size. We are
having a problem with it at the present though, and would appreciate any
information about the variable speed drive. It is one of those double cone
arrangements with hardened steel balls between them. Tilting the axis if the
balls makes the effective radius of the drive and driven cones change, thus
varying the output speed. Our problem is that it will no longer change speed
smoothly from hight to low speed or vise versa.
Has anyone else had this experience? I suspect that the 5 balls are worn
slightly, and I'm considering swapping them upside down to get the load onto
a previously unused section of the ball.
Is this reasonable, or should we just replace it with a shaft and a variable
frequency drive?


I have one of these, which had the same problem. It sounded like
acoffe grinder for a few years of occasional use, then
I was told there are no parts available for them when shortly after I
got mine it croaked in 1992 and I apparently got the last "spider"
for it in the worked, for silly money. They said the insides were worn
and it sounded noisy
When it died again a year ago - 10-15 years later - I got a VFD with
a remote control panel and never looked back. i should have done it
ages ago. You don't get quite the wide speed range, although a 2 step
puly woudl be all ti needs in conjunction with the high - lo wratio
gearbox.
Some info is on www.lathes.co.uk and there is a site with serial
numbers if you want to put a date on it.
Geoff

"Geoff M" wrote in message
...
On Wed, 6 Jan 2010 17:57:05 +1100, "Grumpy"
wrote:

We have a 5X20 Chipmaster at the museum where I volunteer. It has been a
lovely little machine,and is very solid and ridgid for its size. We are
having a problem with it at the present though, and would appreciate any
information about the variable speed drive. It is one of those double cone
arrangements with hardened steel balls between them. Tilting the axis if
the
balls makes the effective radius of the drive and driven cones change,
thus
varying the output speed. Our problem is that it will no longer change
speed
smoothly from hight to low speed or vise versa.
Has anyone else had this experience? I suspect that the 5 balls are worn
slightly, and I'm considering swapping them upside down to get the load
onto
a previously unused section of the ball.
Is this reasonable, or should we just replace it with a shaft and a
variable
frequency drive?


I have one of these, which had the same problem. It sounded like
acoffe grinder for a few years of occasional use, then
I was told there are no parts available for them when shortly after I
got mine it croaked in 1992 and I apparently got the last "spider"
for it in the worked, for silly money. They said the insides were worn
and it sounded noisy
When it died again a year ago - 10-15 years later - I got a VFD with
a remote control panel and never looked back. i should have done it
ages ago. You don't get quite the wide speed range, although a 2 step
puly woudl be all ti needs in conjunction with the high - lo wratio
gearbox.
Some info is on www.lathes.co.uk and there is a site with serial
numbers if you want to put a date on it.
Geoff


Thanks for the information Geoff.

I suspect that that is the way to go. I think I'll just remove the two cones
and shafts and replace them with a through shaft that fits the bearings. A
variable speed with an external pot connected to the original speed change
dial will pretty well fix things at minimal expense and maximum utility.

Thank you for confirming my thoughts.