Newbie trying to thread

That length is no problem - just arrange a supporting centre. I thought there was a centre drilling for that, on the pic.

The angle option is easy without moving the compound slide if you are cutting a 60 degree thread. For every 2 units towards the spindle with the cross slide move 1 unit to the left on the compound slide. This gives an angle of 26.56 but is close enough for what you are likely to be doing. It will give a heavy cut on the left of the cutter and a light cut on the right of the cutter. If cutting a 55 degree Whitworth then this is even closer to the 27.5 degree half angle.

Rotating the compound is often done wrong because the suggested 29.5 degrees is away from the cross slide leadscrew not from the carriage leadscrew. This puts the cross slide and compound slide handles in close proximity and can be awkward to operate. The error beginners often make (hold my hand up here) is to move the compound 29.5 degrees away from parallel to the bed which is 60.5 away from the cross slide leadscrew. This is 31 degrees out of position with predictable rubbish results.

Martin C

@NDIY, yes I had a half dead center to support the work.

@Martin, I initially tried to establish 30 deg by using a precision ground angle plate from a set I bought from Arc but couldn’t get it exact so reverted to a direct plunge method. Your way sounds logical, wish I had thought of that! I find setting the angle on a Myford compound difficult to get exactly right.

Thanks again,

Mark

Congrats Mark,

You did a nice job on that thread.

I find thread cutting is one of the most satisfying jobs going.

Have a practice run on a piece of plastic. Plastic tubing etc..

Bear..

Thanks Bear, good tip, I have enough Delrin lying around to mess around with.

There are lots of variations in threading, I always use threading tools with the laydown triangular inserts. For internal threading I have the choice of normal right handed bars and left handed. The lefthanded are useful as they cut right hand threads away from the chuck with the spindle reversed. The last thread I produced was an Atlas 1 1/2 X 8 chuck backplate, which is similar to a Boxford one. There is a difference in the register and the threads are 60 degrees. I cut that away from the chuck which is easier as there is plenty of time to stop.

The more practice you get in, the easier and more enjoyable it gets. As already recommended, plastic is excellent as its very forgiving of mistakes.

Mart,

Thanks, there's a long way to go! It;'s nice to know there is such a wealth of knowledge here and (more importantly) people willing to share it!

Mark