Making An ER25 Collet Holder for Atlas 618 Lathe

[Topos]

Sirs,

On a site << http://www.deansphotographica.com/machining/atlas/ER25/ER25.html >>
the gentleman made an ingenious collet chuck for the Atlas 618 lathe
which takes the place of the lathe's chuck.

Among many things he showed how to machine the metric
ER25 collet nut's thread ... and the correct transpose gears
to turn an M1.5 thread.

My question:

What metal to use.

Some have said not to use stainless steel as it
could destroy the lathe's steel spindle.

One person said he made one out of brass to protect the threads.

Another used gray iron.

What metal used in lathe chucks and for my  proposed task what
are your recommendations?

Most appreciative, from the Colonies.

[Lew_Merrick_PE]

Topos,

The advantage of steel is that it is harder to "ding" than most other materials.  Heat treating it into the Rc50+ range makes it harder yet to "ding."  A black oxide finish will reduce friction, make it hold lubrication better, and look really nice.  It's accuracy will be defined by the concentricity between the (MT, assumed) taper and the collet's taper.  Keeping the collet's ID lubricated (mineral oil should be fine) falls into the good things category.

As the threads between the collet basis and the clamping nut are completely internal to your collet/nut set, there is no intrinsic reason that they must be metric -- use whatever fits and is convenient for you will be sufficient.

 --  Lew

[Will_D]

A long time ago ( like 30 years , I was making jigs/fixtures/tools out of steel ( various grades FC/HiCarbon/Tool) and got Peed off with finding them rusting away a year later!

Nearly everything I make now is in stainless (303/304 or even 316 [if free])

Modern tooling allows SS to be machined/drilled/tapped as easily as FC MS was in the '80s using HSS on a ML7 or similar

[Topos]

Thank you mates for your wise advice.

Worked my way through University in 1950's doing
menial work in its machine shop (e.g., sorting stock, cleaning
the lathes and milling machines, working on the very first
computer controlled milling machine ) when tuition
was $350.00/ semester during the first 2 years and
then when up to the exorbitant price of $450/semester. 

Gained enduring respect for the machinists, especially the
old curmudgeon who served in Europe  in WW1 working
on aircraft  and weapons repairs. Learned more Middle English
( falsely blamed on  the Anglo Saxons ) words and expressions.

Again my ineffable appreciation and respect for all you 'old
timers' ... we are not old, we just age well like single malt scotch.

Many thanks.

[Lew_Merrick_PE]

A long time ago ( like 30 years , I was making jigs/fixtures/tools out of steel ( various grades FC/HiCarbon/Tool) and got Peed off with finding them rusting away a year later!

Will_D,

1) Black oxide coat steel you do not want to rust.  I have (steel) tools I made as an apprentice (in the 1960's) that are still "black & shiny."

2) Such tools need to be cleaned and oiled every year or so (not much longer than a year), and everything's good.  I live in a part of the world where "rust" is considered a camouflage color.

[ieezitin]

Stainless is fine, dont listen to those old farts, its a little harder to machine on a small lathe but take your time to research carbide verses hss  to machine stainless and everything will workout for you.

I make all my tooling out of stainless when i can but its expensive.

Going to a collet system is the best thing you will ever do, the er range is a wonderful system great clamping range, research the full range of er collet sizes before you make your chuck you may make the larger size, i dont know your gig.

All the best

Anthony