Jim Irwin wrote:
I am considering replacing hte bed and lead screw on my TH42 with one each off a
TH54 and I need some advice before I make a mess.
Are there any important differences in these parts between TH42 and 54?
The leadscrew should be the only thing else you would normally need to change.
The carriage rack is almost a part of the bed, but is removable. Make sure
the longer bed has the rack. Every other part should just slip right into place.
Between 10 and 12 in versions?
Um, yes! The beds are completely different. The flat surfaces the carriage
slides on are thicker and wider apart on the 12". As far as I know, none of the
major components (headstock, tailstock, carriage, cross slide, compound
or QC gearbox) are compatible. The smaller components, like the leadscrew,
the gears in the apron, threading gear chain (except for the bracket all the
gears mount to), spindle and backgear, countershaft, chucks, etc. can be
swapped.
Between QC and non-QC versions?
Generally, the change-gear lathes can be updated to QC by simply removing
most of the gear train and mounting the QC box. There were some
early machines with 5/8" leadscrews that need a bushing to mate with
later hardware. This would be on the very early 10" only. As I mentioned
above, the 10" and 12" QC are not compatible, due to the greater spacing
between the spindle and the leadscrew. If one was willing to do substantial
hacking, you could MAKE it fit, I'm sure. You'd probably need to fabricate
a completely new bracket to hold the gear train coming down from the spindle,
and need to make up some mounting bracket for the box. The 10" QC
has 2 vertical bolts that bolt it to the top of the bed, to the left of the
headstock.
The 12" has 2 horizontal bolts that bolt it to the side of the headstock.
Jon
