Gallery, Projects and General > How do I??
Leveling Denford lathe - has no levelling screws?
chipenter:
It can't be the chuck jaws he has taken a cut then mesured the run out , have you tested the bearings with a dial guage on the top and lifted the test piece .
lordedmond:
Jeff
It could be if the jaws are bell mouthed and no tail stock support was used
As to facing a face plate it should be very slightly dished , to make sure a faced item will sit down flat
Best have a read of Connely's book
I would bet it's the head stock not lined up with the bed
Stuart
chipenter:
Loply I have E.F.Connely's book in PDF if it helps send a pm and I will forward it , how long was the test cut and was the taper even , I spent ten days scraping my Southbend's bed most of the whare was just under the chuck and it's a 42" bed .
DavidA:
Stuart,
..As to facing a face plate it should be very slightly dished , to make sure a faced item will sit down flat..
How does having the faceplate dished make sure that anything bolted to it is flat ?
Let's say I have a piece of 1/2" thick plate six inch long by 2" wide.
I have a faceplate 10" diameter.
The job is to bore a 1" hole centered 2" from the end of the bar..
As one end of the bar would be 1" from the centre and the other end 4" from the centre on the opposite side, how will this hole be true to the surface ?
Surely the bar will not be square to anything as the 'short end' is down in the dish to a much greater extent than the 'long end'.
Dave.
philf:
--- Quote from: DavidA on December 19, 2015, 01:21:17 PM ---Stuart,
..As to facing a face plate it should be very slightly dished , to make sure a faced item will sit down flat..
How does having the faceplate dished make sure that anything bolted to it is flat ?
Let's say I have a piece of 1/2" thick plate six inch long by 2" wide.
I have a faceplate 10" diameter.
The job is to bore a 1" hole centered 2" from the end of the bar..
As one end of the bar would be 1" from the centre and the other end 4" from the centre on the opposite side, how will this hole be true to the surface ?
Surely the bar will not be square to anything as the 'short end' is down in the dish to a much greater extent than the 'long end'.
Dave.
--- End quote ---
That's true David but the amount of dishing is small and could be zero.
There was some discussion on this subject a while ago.
http://madmodder.net/index.php?topic=7066.0
I posted:
I have a copy of Testing Machine Tools by Dr. Georg Schlesinger. (Schlesinger limits are/were often quoted in machine tools specs). In it are various figures given for the lathe facing accuracy.
"For Finish Turning Lathes": "Lathe faces (hollow or concave only) within 0 to 0.02 per 300mm in dia."
"For Toolroom Lathes (Highest Degree of Accuracy)": "Lathe faces (concave only) within 0 to 0.015 per 300mm in dia."
Phil.
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