Don@2480
14th May 2018, 06:18 PM
G'Day All,
After putting up with my lathes (AL300) original 4 jaw chuck backing plate for far too long I decided to do something about it.
The problem being that the fit between the backing plate thread & the lathe spindle nose thread (Ø2.250" x 8 tpi) was to no standard ever used, except by the manufacturer. This resulted in uncontrollable chatter for any reasonable depth of cut & was impossible to part off any size steel workpiece.
As I rarely use a Ø200 4 jaw, I have kept putting this job on the back burner. Now as I need it for a fair bit of turning I have had to do something about it. After acquiring a couple of Ø210 x 45 pieces of mild steel plate I had no more excuses.
Fortunately, the oxy cut surface had been removed by the "supplier" making things a little easier.
373298
Rough material setup to start.
373299
Plate after rear face turned to size & profile.
373300
Plate after bore & register diameter turned to finished size.
373301
After screw cutting, the plate being turned to require thickness & the chuck location spigot turned to size.
373302
The finished plate after milling ops. for the securing screws.
The chatter caused by the old plate can be seen on the thread finish. The last cut had to chatter didn't it, but the fit is good. The plate has to be screwed onto the spindle nose with a spanner on a chuck jaw for the last 10mm now.
So now, decent cuts & parting off can be achieved.
Regards,
Don.
After putting up with my lathes (AL300) original 4 jaw chuck backing plate for far too long I decided to do something about it.
The problem being that the fit between the backing plate thread & the lathe spindle nose thread (Ø2.250" x 8 tpi) was to no standard ever used, except by the manufacturer. This resulted in uncontrollable chatter for any reasonable depth of cut & was impossible to part off any size steel workpiece.
As I rarely use a Ø200 4 jaw, I have kept putting this job on the back burner. Now as I need it for a fair bit of turning I have had to do something about it. After acquiring a couple of Ø210 x 45 pieces of mild steel plate I had no more excuses.
Fortunately, the oxy cut surface had been removed by the "supplier" making things a little easier.
373298
Rough material setup to start.
373299
Plate after rear face turned to size & profile.
373300
Plate after bore & register diameter turned to finished size.
373301
After screw cutting, the plate being turned to require thickness & the chuck location spigot turned to size.
373302
The finished plate after milling ops. for the securing screws.
The chatter caused by the old plate can be seen on the thread finish. The last cut had to chatter didn't it, but the fit is good. The plate has to be screwed onto the spindle nose with a spanner on a chuck jaw for the last 10mm now.
So now, decent cuts & parting off can be achieved.
Regards,
Don.