Richard, Boxing gloves are the best thing I could find. Now typing with a pencil super-glued to the glove!
Does anyone else have a suggestion for cutting fluid for copper and bronze? - for machining and drilling bushes for boilers? I think this could be useful for Bug-Hunter to know as well.
For tapping and external thread cutting boiler bushes etc. with dies, I use a pot of green paste that smells of mint/toothpaste - bought from a guy at a show 20 odd years ago. Works really well, but I think it is the same as the stuff the dental hygienists uses to polish my teeth.... - or denture polish?
https://www.ukdentalsupplies.com/product/prophylaxis-paste/?utm_source=Google Shopping&utm_campaign=Google Shopping&utm_medium=organic&utm_term=334&gad_source=1&gclid=CjwKCAiAt5euBhB9EiwAdkXWO5hl8CzNAusBxSEWjiDEOlwu_5qulN9LUEMRzx7evRhfZDwmIdgWrhoCvxMQAvD_BwE
A tiny amount stops the taps from binding. (a lot just clogs the flutes).
But not so good at speed cutting stuff in the lathe. For cutting holes in copper sheet - e.g. boiler end plates - I use a small pilot drill (1mm - a new drill to be sharp) then a step drill to open the hole in 1mm or 2mm steps to reach the required hole size.
K2
Remembered something (vaguely to be honest) so checked to make sure I wasn't remembering any pure male bovine excrement - - - here's an option.
TL;DR
Try using a brad point drill for a drill geometry on copper (sheet I would think). (Punching your holes might even be preferable - - - dunno.)
Bronze - - - now you need to specify what type of bronze - - - like there are some 7 pages of listings on different coppers and copper alloys in the Machinery's handbook. Looking at a larger distributor (New West Metals if anyone is interested here in North America) there are 'only' 9 categories and some 53 different listed items - - - I'm betting that there are more available just not as readily available.
And you asked only for cutting fluid(s) so I did some looking - - - the German Kupferinstitut offers the following:
(from: Recommended machining parameters for copper and copper alloys)
Some copper-based materials are ma-
chined dry whereas others are machined
while applying a cutting fluid. On some
machine tools, the use of a cutting fluid
is essential as the cutting fluid also
serves to lubricate parts of the machine.
During machining, the cutting fluid
does not normally penetrate to the root
of the chip so that there is no direct
influence of the tool’s cutting edge at
the tool-work contact zone. However,
the cutting fluid can have an indirect
effect on processes at the contact zone
as cooling the workpiece and the tool
increases the temperature gradient that
transports heat away from the work-tool
interface. Additionally, the cutting fluid
can quench the upper side of the chip
and therefore facilitate the curvature
and/or fracturing of the chip. Finally,
the cutting fluid also flushes clean the
machining area.
Whether a cutting fluid functions more
as a coolant or as a lubricant depends
on the machining operation being
performed and the cutting tool used. As
HSS tools only retain their hardness up
to the tempering temperature of around
550–600 °C, cutting fluids are used
primarily as coolants when machining
with HSS. In contrast, carbide tools can
maintain their hardness up to higher
temperatures.
If, on the other hand, the tool has sev-
eral regions that are in direct contact
with the workpiece but that do not con-
tribute to the material removal process
(as is the case with reamers and taps),
then the cutting fluid is more important
as a lubricant than as a coolant.
If the machine tool manufacturer does
not specify the cutting fluid to be used,
emulsified oils are generally preferred
when cooling is the predominant aim.
The favourable cooling properties of
these oil-in-water emulsions are due to
the high specific heat capacity of water.
If, though, lubrication is the primary
concern, cutting oils are preferred to
emulsions. Low viscosity oils are fa-
voured as they are easier to deliver
and remove from the cutting zone.
Cutting oils with added sulphur can
show a propensity to react with copper.
Therefore, either a sulphur-free cutting
oil should be used or the workpiece
should be rinsed immediately after
machining [24].
In cases in which normal cooling-
lubrication by a stream of cutting fluid
(‘flooding’) is not applicable, the fluid
can be applied as a high-speed mist.
In mist application, the cutting fluid
is carried in a pressurized air stream
and deposited in the cutting zone. The
expansion of the air stream is accom-
panied by a temperature drop that also
aids cooling (e.g. when tapping threads
using cutting oil on multistation ma-
chines, which are normally operated
with emulsified oils).
Besides conventional flood-cooling,
copper-based materials can also be
subjected to neardry machining, in
which a minimum quantity lubrication
(MQL) system is used, or dry machining
in which no cutting fluid is used [25].
Both approaches are technologically
feasible for machining copper alloys.
Which cutting fluid is used in practice
depends not only technological feasi-
bility, but frequently also on factors
determined by the machine tool set-up,
such as chip removal, heat dissipation,
lubrication of machine parts, and the
possibility of influencing chip breakage.
(Reading through more of the above document - - - - well there really aren't any clear recommendations - - checked other sites - - - same. I think what you're going to need to specify is the particular kind of bronze you're working with - - - then maybe there are a few bits of information available - - - seemingly not much though! What I'm remembering is mostly - - - make sure your tools are sharp!!)
