FILENAMES: Diehead_1.jpg Diehead_4.jpg Diehead_5.jpg Diehead_6.jpg Diehead_8.jpg Diehead_9.jpg Dieheadparts.jpg DESCRIPTION: These are pictures of adapting a thread cutting die head to a non-turret lathe. Posted by Tim Leech . The following description was provided: ================================================================= There's been correspondence on RCM more than once in the past on the subject of using a die head on an ordinary centre lathe. There's nothing original about what I've done here, but it might be of help to someone else trying to do the same. The scale is perhaps greater than in many home workshops, but the principles will be the same with a smaller lathe & smaller die heads. The aim was to be able to use Coventry die heads in the size range 3/4" to 2" on my TOS SN40C lathe. This is a conventional manual centre lathe with 400 x 1500mm capacity. The 2" die head came with a flanged cast iron mounting block to fit its 3.25" dia shank, probably from a large turret lathe, and I decided to build this into the arrangement. This, in hindsight, was a mistake, and the whole job would have been much simpler, with several fewer machining operations, had I started from scratch with a piece of, say, 4.5" round bar, fabricating a bracket to incorporate it, and boring it in situ on the lathe. Another advantage would be that such a bracket would not intrude so much towards the toolpost, and allow many more normal machining operations to be carried out with the bracket in place. If I find this setup to be used more than just occasionally, I may yet make a new bracket in this way. I fabricated an angle plate to accept the block, from 5/8" plate. This then had to be machined on both external faces plus one internal face. Unfortunately I then found that the top of the cross slide is not sufficiently parallel to the lathe bed, so one face of the angle plate was then re-faced on the lathe, then back to the mill to reface the inside. It is secured to the cross slide , wound right back against the stop, with three 12mm shoulder screws to give a repeatable location. It was bored to the same size as the mounting block bore, the block then secured with four 1/2 inch countersunk screws. I've tested it threading 1inch Whit on some 1inch bar, for the simple reason I had that size of dies and bar to hand. The lathe carriage has to be helped along at the same speed as the threading, but this isn't hard to do. The next job is to make bushes to accept smaller sizes of die head. My guess is that 3/4" will be the smallest to use practically on this size of lathe.