I hang onto broken drill bits and all such scrap to make special cutting
tools for my little (Jet 920) lathe. I have a tiny boring bar I made by
silver soldering a piece of 1/16" drill on a length of key stock.

I never pass on old carbide saw blade, those carbide chips make nice cutters
too.
I prefer a rounded cutting edge on most soft materials.
Familiarity with your equipment is the key to success.

John Ferrell
http://DixieNC.US

----- Original Message -----
From: "Mike Hord" <gaidinmd@HOTMAIL.COM>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Friday, April 09, 2004 7:46 AM
Subject: Re: [OT:] Vertical Mill/Lathe Cutting Speeds


> Three replies in one, to keep S/N ration down...
>
> As for milling plexi with water, that's what we've done in the past.
> It also keeps the tiny flecks of plastic from spreading about and
> sticking to every available surface...
>
> >I have a fairly recent edition but it does not list plastics or delrin.
> >I have not tried milling, but on a lathe it seems the softer the material
> >the more important it is to have a realy sharp tool... HSS, not carbide.
>
> Yep, I've decided to go to "quite fast" but not "stupidly fast".  It may
> be a problem with the lathe, because I think all we have are carbide
> insertable cutters.  We have a very small machine shop, and for the
> most part, I'm the only one using the mill and lathe.
>
> >BTW, the handbook sells pretty cheap on EBAY and there are not a lot of
> >updates in the new ones...
>
> I may just do that.
>
> >Cutting speeds/feeds in SFPM (surface feet per minute) are guidelines
only
> >to start with.  Watch any experienced machinist and he will know the
> >correct speeds by feel.  Depending on the material, feedrate, rigidity of
> >the machine, the type of tool being used, the cutting fluid, etc. the
> >speeds will change.  Typically the home machinist is buying cheap HSS
tools
> >and so you have to watch out for tool wear and run a little bit slower to
> >keep the heat down.  I personally like to buy endmills and lathe tool
> >blanks that are M42 HSS or better, and that pretty much rules out the
> >chinese stuff.  The no brainer way to find out the right speed esp. with
> >plastics is to get some scrap to work with and increase your speeds to
get
> >the best finish on your finish cut, run slower with your roughing cuts.
On
> >plastics there is no need to use cutting fluid.  Cutting fluid is only
used
> >to keep the tool sharp.  On my lathe I never use cutting fluids, only
when
> >using a parting tool.  I think its w!
> >ise for you to pick up a copy of Machinery's Handbook, it will serve as a
> >reference for a lifetime.  I have one and have gone to it for information
> >on many things unrelated to machining.
>
> Thanks for the advice.  We usually only buy higher quality end mills
> from McMaster-Carr, and don't go through them very fast since the
> mill and lathe hardly ever get used.
>
> I'll give more thought to the Handbook.
>
> Thanks all!
> Mike H.
>
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