Compact 5 lathe questions

[Chris TriceParticipant @christrice43267]

[Chris TriceParticipant @christrice43267]

I’ve just bought a Compact 5 lathe without instruction book and although much of the lathes operation is obvious there are a few surprises I wasn’t expecting. Firstly, the bed is cast in an apparently hard grade of iron and beautifully ground but the saddle and its  veeways appears to be cast in Mazak/Zamak and similarly, the base of the topslide. In addition, the gib strips under the adjusting screws appear to be made of a hard engineering plastic akin to nylon, presumably because anything harder is likely to wear the Mazak components. It seems to machine fine but being used to heavier lathes with all iron and steel construction, what is people’s opinions and experience with regards to rigidity and longevity of a Compact 5?

[Chris TriceParticipant @christrice43267]

… and yes, apparently the plastic gib strips are standard.

[Chris TriceParticipant @christrice43267]

… and Doug, you have a PM thanks.

[john jennings 1Participant @johnjennings1]

I have had a Compact 5 for some twenty years.

 >>

The mazak/plastic combination works well even in the long
term.

 >>

The major design fault is the feed nut on the lead screw. I
have replaced this once with a second replacement overdue. The lead screw
itself does not seem to wear but the mazac nut does. I have toyed with making a
“proper” split half nut brass or bronze (or splitting the original mazak nut. I
have however always faltered at making a suitable LH tap to match the lead
screw.

 >>

I operate the saddle feed using a speed controlled
reversible DC motor

 >>

I have always been a bit disappointed with the mill/drill
attachment which is a bit lightweight ; even on a dedicated XY table rather
than the lathe.

 >>

You may be interested in a slow speed banjo to give reduced
spindle speeds (200 rpm is a bit fierce for screw cutting) and a lever operated
tailstock in old issues MEW.

 >>

I also found a simple banjo for LH  threads useful and saved me designing one
(also in an old issue)

[Chris TriceParticipant @christrice43267]

Thanks, that’s all good to know.

 

I agree about the milling head. It’s not very rigid. I’m toying with converting a better unit (suggestions welcome) so it will bolt to the lathe bed via the usual screw holes at the rear and stiffening the lathe bed itself by bolting it to some kind of truly rigid base. While I’m not planning or expecting such a small lathe to turn new propellor shafts for the QE2, I can’t help but feel it’s going to be labouring most of the time turning anything of any size in steel. I suspect what I really want is something along the line of a Cowells but half as big again and with a beefier motor.

 

For interest, the reason I bought it was I was looking for a small precision lathe but small enough and portable enough to be carried by one person in the back of a car.

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