Is a steel frame really necessary. Since it's a moving bed design you can make the frame with as much MDF/wood as you want really and compensate for the strength that way. £50-70 buys you a lot of timber.

Quote Originally Posted by GeorgeD View Post
Irving,if I was to buy the trapozoidal TR16x4? what pitch and threads per inch would I have to set on the mini lathe? I have not mastered this side of the lathe yet in terms of screw threading but will have a go.
Er, are you thinking of threadcutting a nut for that on the lathe? If so that's 4mm pitch, so 25.4/4=6.35TPI ... awkward. If your lathe can do that then youll need to either use a tool with 4 points, or use the compound slide to advance the tool 1/4 of the lead (i.e. 1mm) across to do the next thread etc. That assumes the compound slide is at 0°, if not you'll need to work out the right amount to advance it.

Can't you just make a tap from a bit of spare trapezoidal rod? Standard way with milling a few slots, turning a taper and harden it? Maybe I've missed the point completely!