Member postings for Sean James

Hi All,

I've realised from some of the replies and re-reading my second post that I haven't explained very clearly. There is no wear in the crosslide screw at the extreme ends. The reason that I can't make the tool to fit the screw is as Hopper says, the tool end width must be narrower than the flat at the root of the crosslide thread to give clearance when the threads mate.

I have now made gauges from sheet and it turns out that the thread is Acme (29 Deg.). I have mounted this "Vee plate" gauge onto a height gauge and used it to measure the thread depth, which measures at 0.02mm over the calculated value of 1.5mm (this is about the accuracy tolerance of my height gauge). The tool point width calculates at 0.8mm. so just got to make the tool and get cutting.

Thanks for the feed back.

Sean.

Hi All,

Thanks for your replies. I have the crosslide screw and will probably make sheet metal gauges from it as Hopper suggests. It's not possible to make an accurate tool straight from an unworn portion of the original screw. I am wondering if I should cut the female nut thread slightly deeper, to give slightly more than the normal 10 thou clearance at the thread crest and. This is because the nut is split horizontally on one side, with a pinch bolt to allow slight adjustment to take up wear. Even with the standard 10 thou, the tool point will be narrower than the land at the root of the male thread, and I don't think I'll be able to decide on one degree over about 1.5mm in loose joint when offering up the tool point to the thread. Just thought if someone knew for sure I could "hit the ground running". I may try the photographic method first as it may save som time. Thanks for your help.

Sean.

Hi All,

I have recently bought an "Industrial 11-20" Boxford that requires a new crosslide nut.I have a small manual surface grinder and intend to grind a single point tool to cut the thread. The lathe is a netric model with a 2,5mm pitch L.H. thread on a 12mm diameter crosslide screw. I initialy thought that the thread form would be Trapezoidal, other dimensions being metric. Following some research on the net and other posts on this website I am led to believe that due to the age of the lathe (c.late 1980s), it is more likely to be Acme. Does anyone know for sure the thread form used on these lathes?