Have never done much machining of plastics, but I need to make up some
small parts that will be used in gasoline environment. Looking at the
softer plastics, such as nylon, delrin, teflon etc. Turning, milling,
tapping, possibly some external threading.

Do these plastics machine equally, or somewhat so? Any special
requirements as to clearance or rake angles, lubricants or speeds?

John Martin

In article .com,
says...
Have never done much machining of plastics, but I need to make up some
small parts that will be used in gasoline environment. Looking at the
softer plastics, such as nylon, delrin, teflon etc. Turning, milling,
tapping, possibly some external threading.

Do these plastics machine equally, or somewhat so? Any special
requirements as to clearance or rake angles, lubricants or speeds?


Not enough difference in the machinability of those three to override
other desirable properties. Delrin is probably the most versatile,
nicest to machine, and falls between nylon and teflon in cost.

They're also all pretty forgiving of tool geometry, but I'd suggest
sharp high speed tools with generous nose radius and relatively high
rake and clearance angles. No lube; high speeds as long as good chip
removal can be maintained in order to limit heat buildup.

I know you're somewhere close by. I've got a good sized bin of cutoff
rounds if you want some samples of each to play with.

Ned Simmons

"John Martin" wrote in message
oups.com...
Have never done much machining of plastics, but I need to make up some
small parts that will be used in gasoline environment. Looking at the
softer plastics, such as nylon, delrin, teflon etc. Turning, milling,
tapping, possibly some external threading.

Do these plastics machine equally, or somewhat so? Any special
requirements as to clearance or rake angles, lubricants or speeds?

Can't really tell you which will machine the easiest, but if color has no
bearing on your project, I suggest getting a few different colors to play
with. We have found that the pigmentation in some plastics actually makes
them easier or harder to drill. On one particular part, the white material
drills easily and does not "grab" the bit. The dark gray or black material,
on the other hand is muc harder to drill. The bits grab at the beginning of
the hole regardless of polit hole or not and "spiral" through with a VERY
heavy and unintentional cut when used on manualy fed machines.

It might or might not make a difference for what you want to do, but it
might so... It's worth the $0.00 you paid for the info, right? grin
--


Regards,
Joe Agro, Jr.
(800) 871-5022
(908) 542-0244
Automatic / Pneumatic Drills: http://www.AutoDrill.com
Multiple Spindle Drills: http://www.Multi-Drill.com

V8013-R

On 9 Jan 2006 08:25:49 -0800, "John Martin"
wrote:

Have never done much machining of plastics, but I need to make up some
small parts that will be used in gasoline environment. Looking at the
softer plastics, such as nylon, delrin, teflon etc. Turning, milling,
tapping, possibly some external threading.

Do these plastics machine equally, or somewhat so? Any special
requirements as to clearance or rake angles, lubricants or speeds?

John Martin

It greatly depends on the plastics. Delrin machines well with standard
HSS tooling if you are only doing a few. In production environments
Carbide tooling is needed. It taps, threads and finishes well.

Nylon..well..it makes good spacers, but is poreous and tends to suck
up liquids. Teflon is soft. machines well..taps about as poorly as
nylon..the holes tend to close up somewhat...

Razor sharp tooling. A bit of positive angle. Best tool Ive found for
boring most..not all..but most..is a 2 flute, sharp pointed endmill
held in your tool holder. Has good positive angle, and chip removal is
excellent..well...it directs the long assed strings out of the way
pretty well. Lefthanded ones work marvelously for turning.

My personal choice..take it as you will...for most things is delrin. I
dont know much about gasoline handling abilities of plastics
though..not something Ive needed to inquire about.
Delrin is hard and tends to be a smidge brittle..so impact parts
should be something else. The one time I made a delrin face for a soft
hammer..it lasted about 3 good blows. I now use HDDP for such.

Gunner

The aim of untold millions is to be free to do exactly as they choose
and for someone else to pay when things go wrong.

In the past few decades, a peculiar and distinctive psychology
has emerged in England. Gone are the civility, sturdy independence,
and admirable stoicism that carried the English through the war years
.. It has been replaced by a constant whine of excuses, complaints,
and special pleading. The collapse of the British character has been
as swift and complete as the collapse of British power.

Theodore Dalrymple,

Use polypropylene or polyethylene if it will be exposed to gasoline.

On 9 Jan 2006 08:25:49 -0800, "John Martin"
wrote:

Have never done much machining of plastics, but I need to make up some
small parts that will be used in gasoline environment. Looking at the
softer plastics, such as nylon, delrin, teflon etc. Turning, milling,
tapping, possibly some external threading.

Do these plastics machine equally, or somewhat so? Any special
requirements as to clearance or rake angles, lubricants or speeds?

John Martin

Delryn will absorb gasoline and swell over time. I think teflon is
pretty inert but it's kinda gummy to machine.