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Hi !Here is the picture of a gearbox of a lathe that my fried  bought last week. We are trying to understand how to set the in order to cut a thread.It is possible to cut metric threads?? And imperial threads too ?? Any help is appreciated,John Attached Images
Reply:Metric machine. It will only cut metric threads UNLESS you install a 127:50 gear pair (one inch is exactly 25.4mm. 254:100 is the base ratio) or swap the leadscrew and halfnuts. If the lathe had these gears stock, it would likely be indicated on the chart. Many (most) lathes have a location to install change gears for feeds/threadings that are otherwise not built in, but not all.The chart is easy: The upper number in each box that has one is metric thread pitch (1.0mm, 1.25mm, etc). The lower number is feed in mm/rev. The thread pitch is for feeding with the leadscrew and halfnuts. The feed is for feeding with the rack and apron pinion. DO NOT engage both at the same time.Some machines have a selector at the gearbox (sometimes inside the back of the head) for feed direction and selecting leadscrew or pinion feed. Some use a keyway in the leadscrew rather than a separate driveshaft for the pinion feed. Most select between threading (leadscrew) and standard feed with apron controls. You may need to experiment. Be careful that the controls are fully engaged or disengaged, or you may damage the machine (strip the halfnuts, strip a feed clutch, etc) or damage you.Last edited by enlpck; 01-19-2010 at 09:39 PM.
Reply:Enlcpk:Thank you very muchYour explanation is very well appreciated. Let me play with the lathe and if any other doubt I will ask help again.Regards John
Reply:thanks snlpck  good explanationDaye
Reply:There are some good machining videos on YouTube that may help you.  MIT has an interesting series on machining techniques, too.America Needs AMERICA'S Oil!!!"Global warming is the greatest scam in history ...There is no run away climate change. The impact of humans on climate is not catastrophic. Our planet is not in peril."--John Coleman, Founder of The Weather Channel
Reply:By the looks of the data plate on the gearbox your lathe should be able to cut metric threads.What brand is the lathe?Did your friend get a manual with the machine?Rex
Reply:Hi Rex.The manual is very poor, does not provide information enough.The manufacturer is a puzze. Now American supplier (Standard Modern was a Toronto company which was taken over by Le Blond operating out of some place in the USA)  Any info will be welcomeRegards John
Reply:Post this over on the practicalmachinist.com website. You will get exact answers there.Granthttp://jackalopefab.com/MM210Synchrowave 200DXMiller XMT350 w/60series feederMiller Bobcat 250 with SGA 100 and spoolgunHTP PlasmaFull Machine shop with everything