Lathe coolant applicators

[Nigel Graham 2Participant @nigelgraham2]

JA –

Model engineering does not usually worry about tolerances because it is not part-production manufacturing.#

We make components as well as we can with the equipment and skills we have, so the finished mahine works as well as it should. Not oddles-off Parts A to fits Part B manufactured elsewhere without us having a clue what are A and B in the finished machine. Even if we know what that is.

Your question surfaces fairly often and always receives much as that reply.

I’ve tried to think where we might approach tolerancing in practice, for our own one-off assembly purposes. I’d suggest perhaps: the axles and wheels for a miniature locomotive, to avoid having to make every wheel fit only its dedicated axle-end? In clock-making for correct wheel function? Numerous identical parts like cover studs and nuts for a visually proper finish on a fine-scale model of something like a multi-cylinder marine- or aero- engine?

…..

One digresses…

I have never had too much problem using no more than an old paint-brush as coolant/lubricant applicator, but I am not ramming the tool through the metal at factory rates. Even so it still gives some cooling, especially on horrible stuff like some bronzes.

Where this fails is parting-off because the liquid vanishes from the tool edge within a revolution or two. So a thin stream fed in advance of the cut (i.e. from below with a rear tool-post) would be ideal, although either very extravagant total-loss or needing a full tank and pump system.

I do have such but it’s still sitting under the settee as I’ve not yet decided where and how to use it in my very cramped workshop. My thought was on a trolley for portability between machines. I bought it, an ARC Euro set I think, second-hand with little use, only about eight years ago, too.  Which suggests it’s not exactly vital.

For screw-cutting I usually use neat cutting-fluid as that stays where I tell it. It is less effective in parting, though.

That’s on the lathes. Milling really needs a flood, especially to clear chips from slots and recesses, but that requires a massive chip-tray, shields and reservoir -and a lot of soluble-oil – we cannot all justify.

[Charles Lamont]

On Charles Lamont Said:

…use cutting oil, where appropriate for the material, and in order of importance, for: surface finish, tool life, cooling, and speed.

Out of interest what sort of improvement in surface finish do you see with cutting oil versus dry?

Julie

[martin haysomParticipant @martinhaysom48469]

flood coolant for me then i can keep both hands on the machine, yes it makes a mess so does making swarf. my shop made system is on wheels so can be moved from lath to mill. just need to mod the mill so coolant can drain back to tank

[Julie Ann]

On Julie Ann Said:

On Charles Lamont Said:

…use cutting oil, where appropriate for the material, and in order of importance, for: surface finish, tool life, cooling, and speed.

Out of interest what sort of improvement in surface finish do you see with cutting oil versus dry?

Julie

With steels, hard to say, because I just never cut them dry. From vaguish memory, with anything more difficult than leaded EN1A, it makes a considerable difference – for me.

And I forgot accuracy. With easy material and cutting oil, on a good day I can take 1/2 a thou or less off a diameter.

With one project, trying to get a decent finish on some horribly gummy aluminium castings, I found a solution by going slowly, about the speed for mild steel, and coating the work with Rocol RTD.

[Julie AnnParticipant @julieann]

Thanks for the notes. For basic turning I mostly use carbide and find the solution for getting a good finish on gummy steels, like EN3, is to run fast with decent deep of cut and feedrate. When I have time I might try cutting with and without coolant and see if I can measure any difference.

Julie

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