[TheForge] Delrin hammer guides?

Tue Apr 8 00:06:00 2003

Delrin also make a spiffy knife handle for harsh environments

                            Grant Marcoux
----- Original Message -----
From: "Paul Hewitt" <[email protected]>
To: <[email protected]>
Sent: Monday, April 07, 2003 7:01 PM
Subject: Re: [TheForge] Delrin hammer guides?


> Actually in my haste I forgot to list the materials I prefer as bearing
> guides, delrin is one, also nylatron, which is impregnated with oil, so no
> grease or oil is ever required.  both of these materials do well in a high
> abrasive variable temperature environment.
>
>
> ----- Original Message -----
> From: "gblacksmith" <[email protected]>
> To: <[email protected]>
> Sent: Monday, April 07, 2003 9:56 AM
> Subject: [TheForge] Delrin hammer guides?
>
>
> > All hands:  Could you use Delrin (acetal) in this application?
> >
> >                                         Grant
> > ----- Original Message -----
> > From: "Tom Troszak" <[email protected]>
> > To: <[email protected]>
> > Sent: Monday, April 07, 2003 5:40 AM
> > Subject: [TheForge] Re: UHMW hammer guides
> >
> >
> > > Message: 4
> > >     Date: Sun, 06 Apr 2003 21:59:29 -0700
> > >     From: Ian <[email protected]>
> > >     To: TheForge <[email protected]>
> > >     Subject: [TheForge] Air Hammers
> > >     Reply-To: [email protected]
> > >
> > >     Instead of using brass bearings for the hammer and slider, has
> anyone
> > > used
> > >     UHMW ...
> > >
> > > Dear Ian,
> > >
> > > I have made dozens of power hammers using UHMW for guides.  The most
> > > important thing is that the steel side has to be smooth at lease a 60
> > > microinch finish or better.  I have built some hammers that strike
> > > 30,000,000 blows per year, and the brass guides had to be replaced
every
> > > three or four months as the brass needs constant oiling, and most guys
> oil
> > > about once a day. The good thing about brass guides is that even after
> > > 100,000,000 blows, the rams still looked like new.  When the brass
> guides
> > > were replaced with UHMW, there was no appreciable wear on the UHMW
after
> > > even six months.  However, in a solid fuel shop, (coal or coke fires),
> or
> > a
> > > place where you do a lot of grinding, microscopic particles of grit
get
> > > "bedded" in the plastic forming a "lapping tool" which actually eats
the
> > > steel. there does not seem to be a good cure for this, but the grooves
> in
> > > the steel do not seem to impair the performance, they just look "bad".
> > >
> > > Brass guides can be tightened up to a very "crisp" alignment with only
a
> > few
> > > thousanths play and still slide well, UHMW guides always feel a little
> > gummy
> > > by comparison. You have to make a fairly tight fit, almost pinching to
> get
> > > rid of the "wobble" but the UHMW is so slippery that it works well.
The
> > UHMW
> > > has virtually no structural strength at all, so in any application it
> > needs
> > > to be "backed up" structurally some way. UHMW is very spooky stuff. An
> > > unsupported bar will deform from it's own weight, yet it is virtually
> > > indestructible in many applications, but rough surfaces will erode it
> > fairly
> > > quickly.
> > >
> > > Another plastic that I have used successfully for hammer guides is
> > > oil-filled nylon, also called Vecton (and other names I'm sure)  It is
> > olive
> > > green in color and is structurally much stiffer and tougher than UHMW.
> I
> > > have used it in fully automatic applications where no lubrication is
> > > allowed. It is not usable for food grade applications, however. You
just
> > > "prime' it with a little swipe of light oil as you assemble the
machine
> > and
> > > then it runs for years with no further oil.  The steel side needs to
be
> > > smooth, as with UHMW.  Believe it or not, regular nylon works pretty
> well
> > > even without constant lubrication, but I would not recommend it for
high
> > > speed applications.  I discovered this by accident when a supplier
> > > accidently send plain nylon instead of the oil-filled stuff, the
hammer
> > ran
> > > great anyway.  It is more expensive than brass, but very cool stuff.
> The
> > > caution about dirt applies here as well. It is not as slippery as the
> > UHMW,
> > > but perhaps a little more slippery than bare brass.
> > >
> > > I hope this is useful.
> > >
> > > Tom Troszak
> > >
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