Delta 1440 wobble question

[Rick Smith]

I bought a new Delta 1440. When I screw on my NOVA midi chuck, it "wobbles" (turns out of true). Thought it might be the shaft, but the 6" faceplate and Supernova do not "wobble". I have tried "washer shims" thinking that it is because the midi does not fully seat. Not working! Any suggestions?

[Dario Octaviano]

Sounds like the Nova midi chuck is your problem since the lathe works okay with the rest.

[George Tokarev]

Remove the insert, if so equipped, and clean the seats and threads. Not unknown to get a bit of crud in there, or have a burr from thread cutting. Then carefully re-mate the cleaned pieces, not honking the insert down, but just seating it before you set the grub screws. Had one chuck like that from the guy who sold me this lathe. Still can't figure out why he put up with it, but after I cleaned the mating surfaces, it ran true.

If no insert, check the bottom where the spindle might contact it for the same.

[Bill Boehme]

If it were a Oneway chuck, the following drawing might help the situation. Basically, the problem is that the stop at the end of the threads is not a good register on many of the Delta lathes. I sent a drawing to Kevin at Oneway to make a modified insert for me. The attached figures indicate the proper register areas. Register #1 would be the annular section where a mating counterbore can be made in the insert to provide close radial alignment tolerances and Register #2 is the flat surface that the end of the insert registers against to provide angular alignment. I have found that because many turners are not machinists or engineers do not know that threads alone do not provide any sort of alignment accuracy and the stop at the base of the threads is too small to be an effective register especially considering that Delta has slightly undersized threads which make for a loose fit. If NOVA will build a custom insert then you may be back in business. I replaced the spindle on my lathe (on Delta's nickel) because even though the MT was concentric with the spindle axis of rotation, the threads were slightly catty-wompus (this is an engineering technical term meaning FUBAR). The spindle pictured is the one replaced.

Bill

[Gordon Seto]

There is no insert for the Nova Midi chuck; it is direct threaded.

Gordon

[Bill Boehme]

There is no insert for the Nova Midi chuck; it is direct threaded.

Bummer ....... check the spindle for runout with a dial indicator and especially check the semi-pseudo-register at the base of the threads for radial flatness -- You can actually use a skew to true up a bad surface -- use it like a scraper please and be very gentle on removing metal. This will take care of burrs and nasties, but if the thread fit is loose, then that may not be enough. Also, follow George's advice.

Bill

[George Tokarev]

Before I started scraping metal from the machine, I'd glue on a wooden wafer and true it just to verify that all my screw-mounted accessories worked with it. Here's betting that fixing the one will mess with the others if the spacer method is used.

[Rick Smith]

Gentlemen, thanks for the advice! I took the insert from the supernova and screwed it on first, then the midi, hoping to bring a "true" seating surface further out for the midi to comtact. Kind of a last ditch effort... It works! The spindle threads only go into the midi about 3/4 of the way, but it's solid.

[George Tokarev]

Good. Means it's a bottoming problem with the chuck itself rather than the lathe. Makes it possible to scope and clean the chuck for a solution, or to get a precision washer or spacer to keep the predominant alignment on the shoulder, where it should be. I'd make it a bit shorter than the insert, were I you.

[Drake Harvey]

Bill,

Do you know if it is possible to order this custom part for the Talon from OneWay directly?

Drake