Brandenberger
Hot Rolled
- Joined
- Sep 19, 2017
Hi,
I have a Kent TRL-1340 lathe which is quite new but had premature wear
in the cross-slide and saddle casting. Largely due to the cross-slide being
surface ground, and the saddle casting being poorly scraped and not deburred around
the oil grooves.
I have scraped the underside of the cross-slide flat. Now I intend to use it
as a template to scrape the saddle. However I wanted to check the tolerances for
alignment and parallelism.
To check alignment as suggested in Connelly, I put a parallel in the chuck, and
rotated the chuck 180degrees with an indicator showing zero-zero (Figure 26.63 in
Connelly). When I test the sliding compound against this, I get a few tenths, and
in the right direction (would face a concave disc) as per Connelly Figure 26.64.
So far so good.
When testing the existing saddle mating surface for the cross-slide however, it is .0035"
high in the rear vs the front, as measured from the flat ways of the bed. On this lathe
bed the flat ways are parallel, the v-ways are different heights.
Since the lathe bed is hardened and unworn, that is an easy reference surface to use, to ensure both lateral and longitudinal parallelism of the cross-slide / saddle surfaces versus the lathe bed flat ways. What I'm not sure of is whether I should leave the rear high slightly to compensate for tool pressure?
Some pictures (apologies, I'm having problems getting decent resolution pictures posted these days, the uploader seems to downsample them badly)
Thanks,
Phil
I have a Kent TRL-1340 lathe which is quite new but had premature wear
in the cross-slide and saddle casting. Largely due to the cross-slide being
surface ground, and the saddle casting being poorly scraped and not deburred around
the oil grooves.
I have scraped the underside of the cross-slide flat. Now I intend to use it
as a template to scrape the saddle. However I wanted to check the tolerances for
alignment and parallelism.
To check alignment as suggested in Connelly, I put a parallel in the chuck, and
rotated the chuck 180degrees with an indicator showing zero-zero (Figure 26.63 in
Connelly). When I test the sliding compound against this, I get a few tenths, and
in the right direction (would face a concave disc) as per Connelly Figure 26.64.
So far so good.
When testing the existing saddle mating surface for the cross-slide however, it is .0035"
high in the rear vs the front, as measured from the flat ways of the bed. On this lathe
bed the flat ways are parallel, the v-ways are different heights.
Since the lathe bed is hardened and unworn, that is an easy reference surface to use, to ensure both lateral and longitudinal parallelism of the cross-slide / saddle surfaces versus the lathe bed flat ways. What I'm not sure of is whether I should leave the rear high slightly to compensate for tool pressure?
Some pictures (apologies, I'm having problems getting decent resolution pictures posted these days, the uploader seems to downsample them badly)
Thanks,
Phil