Registration boss saftey issue

[Lance]

Hi all,
I have a question about something that may pertain to saftey.
I have finally amassed enough tooling to start a build, and made it to the point of where I needed a 4 jaw chuck.
Having an Enco lathe/mill I have run into the problem that they do not make a 4 jaw that is a direct bolt on. So I ordered one that was for a 7-10 lathe with an adapter plate. It doesn't fit either but with drilling and tapping 2 holes it will bolt directly on without the plate. The only problem is the registration boss is much larger on the chuck than the spindle.
So here is the question, other than centering will this affect the saftey-holding power of the chuck to the spindle? I do not want to play catch with a 10 pound chuck spinning at 1000 rpm.
If it is an issue I can make an adapter that will fit, but that makes the chuck stick out another 3/4 inch on a machine where space is already at a premium.:wall:
Thanks in advance
Lance

 

[lensman57]

Hi all,
I have a question about something that may pertain to saftey.
I have finally amassed enough tooling to start a build, and made it to the point of where I needed a 4 jaw chuck.
Having an Enco lathe/mill I have run into the problem that they do not make a 4 jaw that is a direct bolt on. So I ordered one that was for a 7-10 lathe with an adapter plate. It doesn't fit either but with drilling and tapping 2 holes it will bolt directly on without the plate. The only problem is the registration boss is much larger on the chuck than the spindle.
So here is the question, other than centering will this affect the saftey-holding power of the chuck to the spindle? I do not want to play catch with a 10 pound chuck spinning at 1000 rpm.
If it is an issue I can make an adapter that will fit, but that makes the chuck stick out another 3/4 inch on a machine where space is already at a premium.:wall:
Thanks in advance
Lance

Hi,

Having owned and "disowned" a Sieg C1 micro lathe for the past 18 months or so I can certainly understand your frustration and concern about the different standards of chuck mounting "options".
The registration boss serves no purpose than to help in " aligning" the chuck with center of rotation, in most Chinese lathes this no more than 2~3 mm thick which is enough to hold the chuck, the bolts are main feature to secure the chuck. I have faced my dapter plate on the spindle and have increased the length of the boss by 0.5 mm for peace of mind, as it has not done anything to improve accyraccy. If however the chuck register is a lot larger than the spindle boss you may be able to turn an adapter between the spindle boss and the chuck register to fill the gap and bring the chuck to concentricity with the spindle provided that there is enough of a gap to do so.

It is all fun and games with these Chinese lathes and mills.

Regards,

A.G