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View Full Version : Question for Nardini lathe owners.



Boucher
08-10-2010, 10:10 PM
My Nardini lathe a TT1230E does not have a 13 or 14 TPI listed in the gear settings. It does however have a 13 1/2 setting. Is this problem common in other models?

Is 1/2 a thread close enough? I have been meaning to turn a 1/2 X 13 1/2 thread and see how long of a nut can be put on it.

When I run headlong into this problem I am normally in a hurry and either use a Die or just change to a fine thread pitch.

This is really a nice lathe but this deficency boggles my mind.

Your input on this would be appreciated. I will post tomorrow with how far a coupling nut will screw on.

Dr Stan
08-10-2010, 10:20 PM
1/2 thread off will not work well. I'd take a look at the gear train to see if you can change some gears and double the speed of the lead screw then set the gear box for 26 TPI.

Don Young
08-10-2010, 11:03 PM
Yes, it is very common for a quick change gearbox to have lots of threads you never need but not the one you do need! If your lathe will not cut 13 or 14 TPI It is very unlikely that it will cut 26 or 28 TPI. The 13 1/2 TPI setting is probably not as common as 27 TPI, which is used on some small pipe threads.

If your gear train has a "driven" gear with a number of teeth which is an integral multiple of a TPI setting on your gearbox, then changing that gear will change the resulting TPI proportionally.

For example if there is a 32 tooth "driven" gear and there is a 16 TPI gearbox setting, changing that gear to 26 teeth will cut 13 TPI at that gearbox setting. Someone probably has figured it out and hopefully you will get a more specific answer. Otherwise you just have to examine the gear train and the settings of the gearbox to figure out what can be changed. Don't forget that you must have some method of changing the gear spacing, such as a banjo for this to work. Even then, it may not be possible to get the desired gear to fit and mesh correctly.If you gear train spacing cannot be changed then you will either have to change more than one gear or make other modifications to the gear train.

It's really pretty simple in theory, but figuring out what can actually be changed and still work is specific to each model of lathe.

How far you will get mis-matched bolts and nuts to thread is somewhat dependent on the thread clearance. Sometimes a useful engagement can be made but the strength will be very poor in relation to a proper fit.