Grayson lathe crosslide

I was just wandering if the crosslide from a Myford would fit on a Grayson lathe

Do you mean crosslide or topslide? I think there would be quite a high probability but crosslides are not often sold 'loose'. Also look at Drummond parts. A starting point would be to list the pertinent dimensions on here and see if someone will add the equivalent for a few models of Myford.

I've seen the parts listed on eBay but he's not selling the crosslide just the top and the apron. At the top of my dovetail it measures 54mm and is about 9 mm high

To be honest there's not a lot if anything wrong with my crosslide it fits nicely and any side movement can be taken up with the gib. The only thing wrong is the backlash on the lead screw. If it was a myford I could replace either the nut or the screw or both as their readily available. But with the Grayson the screw goes through the casting which is not replaceable and also the lead screw is 8 tpi as aposed to 10 tpi on the myford.

I was wondering whether it was worth drilling the thread out and fitting the myford screw and nut or am I in for a world of hurt

Many years ago when I refurbed my first lathe - a Grayson - I bored out the worn cross slide thread and replaced it with an acme threaded PB bush. The thread in the bush was roughed out on a friends lathe and finished with a hardened and ground tap which I was allowed to make in a tool room in which I was working at the time. It was a labour intensive job but turned out well. I just regret that I was careless enough to lose the tap which had so much work invested in it.

Rik

If the screw goes through the casting then you need the saddle anyway not the crosslide. IT all looks like a copy of the Drummond. However the saddle is less likely to be a good fit on your bed and is probably just as worn as yours.

There are three main areas contributing to the backlash.
1. the setting of the screw and the handle and nut (I'm guessing it is the same as the Drummond and ML1 ) This takes some care and is often worn and scored. Thin brass washers might help improve the wear surfaces here.
2. the variation in wear of the screw itself at the middle compared to the ends. You can measure this variation with a DTI.
3. The wear in the 'nut' which is part of the saddle in this case. This can be sorted with a backlash adjusting nut. This is a small brass nut say 1/4 inch so two threads which can be quite a sloppy fit. Put this on the outside face of the saddle 'nut' and with the screw at the least worn section do up the brass nut to lock it all up. Back off a tad to free it up and lock the brass nut there so it can't rotate. You will need to use some ingenuity for this.