trouble threading bolts

Upside down is correct. If you change the direction of feed then you must change the rotation which means upside down tools. If you want the same thread.

Part of the fun of cutting threads is working up to the bolt head, and stopping just before you crash! Usually people use a rear mounted tool and run the lathe backwards if this is a big issue. Using an upside down tool and running backwards will tend to lift the carriage off the ways, which is bad. Often there are no gibs to hold the carriage down, just the normal cutting force.

Center drill the bolt head for a live center in the tailstock, hold the off-cut portion of the shank in the lathe chuck, thread normally from the bolt head as far as you need and then chamfer and part off the bolt.

Brian

Or, cut with the tool on the back side of the work. Then its right side up and easier to see what you're doing.

Karl

The direction of travel of the threading tool was just backwards. Throw the tumbler gear into the other direction and all will be well. Then again, make up left handed nuts to go with that bolt and really mess with the minds of those who come later trying to take your stuff apart.

-- Bob May Losing weight is easy! If you ever want to lose weight, eat and drink less. Works evevery time it is tried!

And then reaction force is pushing the cross slide down into the bed instead of lifting it. My gibs can take cutting on the back side, but bind up if I run the tool upside down.

StaticsJason

OOoo - Nasty! - I love the concept - providing that you remember what you did when the time comes to take it apart yourself. (GBG) Now *that* is the stuff of great embarassment. Ken.