TO all willing to give experience to new smith,

Have been tooling up my new shop and last night I decided it was time to level my new Jet GH-1440ZX lathe.

I am using a Starrett machine level to do the measuring. Leveling the bed under the head stock was a breeze. But then as I measured down the bed ways to the tail stock, the closest I could get was roughly 1/2 a measuring segment on the level. The segments on this level equal 0.005" elevation change at one foot.

Figuring this to the distance between my ways, it comes out to around 0.0022" to 0.0023" of twist from the headstock to the tailstock over 40".

When I tried to get the ways leveled closer then this 1/2 segment, the front support on the tailstock end simply lifts off the ground. I know this is simply a result of the extreme rigidity and strength of the casting but it really limits the range of adjustment with this big gunsmithing lathe.

My first question to all of you is, is this enough to cause an accuracy problem when cutting over the 40" span?

The test sheet that came with the lathe states that the bed ways should be within 0.0016" over 40".

If this will be a problem, would any of you know how to correct the problem without sending the machine back to the company?

I was looking at the machine and it has a flood coolant system housed under the tailstock. It seemed it would be easy to drill a 1/2" hole in the casting in the front corner under the tail stock and use a 1/2" concrete anchor to allow me to pull the front of the casting to the ground to perfectly level the ways.

It would only take a fraction of a turn on a bolt to perfectly level the ways in this manor but really am a bit cautious to drill on a new lathe.

ANy ideas on if this is even a problem or not and if so how to correct it would be most appreciated from this upstarting gunsmith.

Thank you for your time.

50

Normally the lathes come with leveling instructions with nice diagrams. It sounds like you have twisted your lathe. As you level cross ways you typically put the level on the crossslide in your x axis, your z axis is the 40" length. You typically have 4 screws at the head and two at the end of the tailstock. Start with the two under the chuck touching a little the other two raised a little. Now the lathe is on 4 screws. Adjust the twist out accordingly by leaving the level and running the saddle down the z axis. After thats close rotate the level 90 deg. You will then have a slight crown in the middle of the bed which is where the back two come in. But don't twist the bed again so you have to monitor it close by checking both dir. Mark lines on the crosslide to put the level in the same spot each time. It goes a little faster when your on the crosslide.

I used to build machines for Giddings & Lewis (among others). On the first attempt at leveling a machine base we would get things as close as possiable the first day, than let it sit for 24 hours, and level again. It often took 2-3 days to get a base setting true before we could start doing the actual build.
Leave the high corner (slightly) unsupported overnight and see if it settles down (yes the frame will "walk" into position).