Injection molding forum?
steamer
to discuss this topic? I'm taking a whack at making a small injection
molding die for a small, but fairly odd piece..
--
"Steamboat Ed" Haas : Blue Cross socks us
Hacking the Trailing Edge! : $23,000/yr!! ...
www.nmpproducts.com
---Decks a-wash in a sea of words---
John R. Carroll
> --Doesn't seem to be one on usenet (!!) Can someone suggest a place
> to discuss this topic? I'm taking a whack at making a small injection
> molding die for a small, but fairly odd piece..
I could probably help out a little Ed.
I've done a lot of things but one of them was 30 years designing and
building injection molds.
--
John R. Carroll
Spehro Pefhany
I have a post-grad certificate in plastic injection mold design, but
John would probably be a better bet.
Richard J Kinch
> Can someone suggest a place
> to discuss this topic?
I would also like to know some small-scale feasibility. I'm paying
$25/each for injection-molded camera hot-shoe connectors for which I have
found exactly one supplier in the universe.
John R. Carroll
That's not a bad price if the contacts are inmolded.
--
John R. Carroll
Karl Townsend
>>I could probably help out a little Ed.
>>I've done a lot of things but one of them was 30 years designing and
>>building injection molds.
>
> I have a post-grad certificate in plastic injection mold design, but
> John would probably be a better bet.
I've got a few years under my belt running injection mold presses. Only
complete hydraulic, no toggles. Mostly on HPM and Cincinnati. My focus was
on running them faster, adding pickers, going to runnerless molds, etc. Not
much prototype work.
Karl
steamer
a die to make these: http://www.nmpproducts.com/nmp02.htm
--I dreamed this up more than a decade ago and I've given up on
trying to get a die made that costs less than any potential worldwide sales
of the widget in question. Sooo I've managed to carve out the fin part of
the cavity with a Bridgeport and my little Sherline rotary table (total
depth of fins not right due to short endmill; longer ones back ordered). But
making the 3 inserts (and the plate that will hold them accurately) is
getting a bit tricky. Will try to post some photos to my blog in a day or
two.
--I'm thinking of pouring in an epoxy of some kind as I really don't
want to injection mold them until I get the geometry of the die just right.
Gotta figure out what's available that has the correct durometer; something
like nylon would be ideal.
--I've got one of those 1/3 oz injection molding machines that
a now-gone supplier of same for trade schools sold many moons ago but it
needs to be thoroughly gone thru as it's been sitting idle under the
workbench forever; that's another can of worms I'll need to open eventually..
Pete C.
steamer wrote:
>
> --Aha! Looks like RCM is da place after all. Well I'm trying to make
> a die to make these: http://www.nmpproducts.com/nmp02.htm
> --I dreamed this up more than a decade ago and I've given up on
> trying to get a die made that costs less than any potential worldwide sales
> of the widget in question. Sooo I've managed to carve out the fin part of
> the cavity with a Bridgeport and my little Sherline rotary table (total
> depth of fins not right due to short endmill; longer ones back ordered). But
> making the 3 inserts (and the plate that will hold them accurately) is
> getting a bit tricky. Will try to post some photos to my blog in a day or
> two.
> --I'm thinking of pouring in an epoxy of some kind as I really don't
> want to injection mold them until I get the geometry of the die just right.
> Gotta figure out what's available that has the correct durometer; something
> like nylon would be ideal.
> --I've got one of those 1/3 oz injection molding machines that
> a now-gone supplier of same for trade schools sold many moons ago but it
> needs to be thoroughly gone thru as it's been sitting idle under the
> workbench forever; that's another can of worms I'll need to open eventually..
You are aware of the widely available and very inexpensive quick stop
clamp nuts:
http://www.use-enco.com/CGI/INSRIT?PARTPG=INSRAR2&PMAKA=209-9003&PMPXNO=945606
(Currently a whopping $4.25)
Or the slightly fancier and more difficult to install version:
http://www.use-enco.com/CGI/INSRIT?PMAKA=505-2178&PMPXNO=949443&PARTPG=INSRHI
Spehro Pefhany
> --Aha! Looks like RCM is da place after all. Well I'm trying to make
>a die to make these: http://www.nmpproducts.com/nmp02.htm
Cool.
> --I dreamed this up more than a decade ago and I've given up on
>trying to get a die made that costs less than any potential worldwide sales
>of the widget in question. Sooo I've managed to carve out the fin part of
>the cavity with a Bridgeport and my little Sherline rotary table (total
>depth of fins not right due to short endmill; longer ones back ordered). But
>making the 3 inserts (and the plate that will hold them accurately) is
>getting a bit tricky. Will try to post some photos to my blog in a day or
>two.
Steel or aluminum? You planning on unscrewing a threaded bit to get it
out?
> --I'm thinking of pouring in an epoxy of some kind as I really don't
>want to injection mold them until I get the geometry of the die just right.
>Gotta figure out what's available that has the correct durometer; something
>like nylon would be ideal.
Have you looked at cast urethane (you probably have a vacuum pump for
degassing)?
For a test run you could also consider doing rapid protyping, but it
will be a few hundred dollars cost most likely.
> --I've got one of those 1/3 oz injection molding machines that
>a now-gone supplier of same for trade schools sold many moons ago but it
>needs to be thoroughly gone thru as it's been sitting idle under the
>workbench forever; that's another can of worms I'll need to open eventually..
Is 1/3-oz enough?
Richard J Kinch
> http://www.nmpproducts.com/nmp02.htm
Cute, but the this threaded feature on the Bridgeport is an obsolete analog
item. Replace it with a flatted rod and thumbscrew clamp, and measure with
a DRO, better/faster/cheaper.
Jon Anderson
> --Aha! Looks like RCM is da place after all. Well I'm trying to make
> a die to make these: http://www.nmpproducts.com/nmp02.htm
Lordy Ed, I remember when this first appeared in Machine Design! Hope
you finally get it off the ground and make some $$ with it!
Jon
steamer
>You are aware of the widely available and very inexpensive quick stop
>clamp nuts:
go .05" too deep? ;-)
steamer
>On 17 Feb 2010 17:40:36 GMT, steamer <ste...@sonic.net> wrote:
>> --Aha! Looks like RCM is da place after all. Well I'm trying to make
>>a die to make these: http://www.nmpproducts.com/nmp02.htm
>Cool.
>> --I dreamed this up more than a decade ago and I've given up on
>>trying to get a die made that costs less than any potential worldwide sales
>>of the widget in question. Sooo I've managed to carve out the fin part of
>>the cavity with a Bridgeport and my little Sherline rotary table (total
>>depth of fins not right due to short endmill; longer ones back ordered). But
>>making the 3 inserts (and the plate that will hold them accurately) is
>>getting a bit tricky. Will try to post some photos to my blog in a day or
>>two.
>Steel or aluminum? You planning on unscrewing a threaded bit to get it
>out?
--Aluminum. Threading occurs after molding, when two parts are
snapped together; makes the making of the mold much easier.
>> --I'm thinking of pouring in an epoxy of some kind as I really don't
>>want to injection mold them until I get the geometry of the die just right.
>>Gotta figure out what's available that has the correct durometer; something
>>like nylon would be ideal.
>Have you looked at cast urethane (you probably have a vacuum pump for
>degassing)?
--Yes; have vac pump but want to avoid the step if possible.
>For a test run you could also consider doing rapid protyping, but it
>will be a few hundred dollars cost most likely.
--Heh. For my next project I'm going to build a Mendel
(http://objects.reprap.org/wiki/Mechanical_construction) so's I can make 'em
that way but I really don't think the resolution is good enough yet..
>> --I've got one of those 1/3 oz injection molding machines that
>>a now-gone supplier of same for trade schools sold many moons ago but it
>>needs to be thoroughly gone thru as it's been sitting idle under the
>>workbench forever; that's another can of worms I'll need to open eventually..
>Is 1/3-oz enough?
--Oh yeah; plenty big enough.
steamer
>> http://www.nmpproducts.com/nmp02.htm
--Different strokes for different folks; I've used the prototype for
over a decade: no complaints..
steamer
--Heh. Yah, sometimes it takes me a while to get around to something
but the time has finally come for this one!
Pete C.
steamer wrote:
>
> Pete C. <aux3....@snet.net> wrote:
> >You are aware of the widely available and very inexpensive quick stop
> >clamp nuts:
> --Yeah, yeah, been there, done that. Ever have one slip on you and
> go .05" too deep? ;-)
Nope.
Pete C.
steamer wrote:
>
> Spehro Pefhany <spef...@interlogdotyou.knowwhat> wrote:
> >On 17 Feb 2010 17:40:36 GMT, steamer <ste...@sonic.net> wrote:
>
> >> --Aha! Looks like RCM is da place after all. Well I'm trying to make
> >>a die to make these: http://www.nmpproducts.com/nmp02.htm
>
> >Cool.
>
> >> --I dreamed this up more than a decade ago and I've given up on
> >>trying to get a die made that costs less than any potential worldwide sales
> >>of the widget in question. Sooo I've managed to carve out the fin part of
> >>the cavity with a Bridgeport and my little Sherline rotary table (total
> >>depth of fins not right due to short endmill; longer ones back ordered). But
> >>making the 3 inserts (and the plate that will hold them accurately) is
> >>getting a bit tricky. Will try to post some photos to my blog in a day or
> >>two.
>
> >Steel or aluminum? You planning on unscrewing a threaded bit to get it
> >out?
> --Aluminum. Threading occurs after molding, when two parts are
> snapped together; makes the making of the mold much easier.
In that case, forget injection molding and think extrusion. You've got
something that's basically like a big T05 heatsink, so you should be
able to extrude as a complete part (no snap together) and then slice
into the appropriate lengths.
You could also just lathe and mill it with a 4th axis, taking a solid
plastic rod, bore the center hole on the lathe, then put in 4th axis on
the mill and mill the fins. A 24" rod should yield like 45 parts.
Denis G.
If you haven't already seen it, then this site might interest you:
http://www.hobbymolding.com/forum/
steamer
>In that case, forget injection molding and think extrusion. You've got
>something that's basically like a big T05 heatsink, so you should be
>able to extrude as a complete part (no snap together) and then slice
>into the appropriate lengths.
made by experts and the price goes up accordingly. I want to do it all 'in
house' so's it becomes more cost effective. Die's almost done now; hope to
get some epoxy parts out of it soon.
>You could also just lathe and mill it with a 4th axis, taking a solid
>plastic rod, bore the center hole on the lathe, then put in 4th axis on
>the mill and mill the fins. A 24" rod should yield like 45 parts.
--Not set up to do this either. Sigh..
Terry
>Pete C. <aux3....@snet.net> wrote:
>>In that case, forget injection molding and think extrusion. You've got
>>something that's basically like a big T05 heatsink, so you should be
>>able to extrude as a complete part (no snap together) and then slice
>>into the appropriate lengths.
> --The thought has crossed my mind but again it becomes a part best
>made by experts and the price goes up accordingly. I want to do it all 'in
>house' so's it becomes more cost effective. Die's almost done now; hope to
>get some epoxy parts out of it soon.
Instead of epoxy, do a search for "casting resin" on Ebay. A
half-gallon kit is $30 (plus shipping), a two-gallon kit is $80. Much
thinner than any epoxy I've used so degassing may not be necessary,
hardens in about five minutes, no significant exotherm in small parts,
nice off-white color, tough product.
Just a satisfied customer.
Best -- Terry
steamer
>Instead of epoxy, do a search for "casting resin" on Ebay. A
>half-gallon kit is $30 (plus shipping), a two-gallon kit is $80. Much
>thinner than any epoxy I've used so degassing may not be necessary,
>hardens in about five minutes, no significant exotherm in small parts,
>nice off-white color, tough product.
steamer
steamer
the inserts today and have only to thread two holes and bore an entry port
for injection molding nozzle to finish the die.
--Did quite a bit of searching for pelletized Nylon and finally
settled on a supplier. But there's a minimum purchase quantity of 55 pounds
so I'm going to wind up with a wee bit more than I need! Anyone want some??
Ecnerwal
steamer <ste...@sonic.net> wrote:
> --Did quite a bit of searching for pelletized Nylon and finally
> settled on a supplier. But there's a minimum purchase quantity of 55 pounds
> so I'm going to wind up with a wee bit more than I need! Anyone want some??
I have too many projects and not enough time, but I've always thought
about using some of the "easier" recyclable thermoplastics - though I
don't really know what I'd be getting into there. Figure some sort of
process like shred, blow dry hot nitrogen through to dry and eventually
melt (guessing that oxygen may be an issue with some plastics at high
temperatures), perhaps an intermediate extrude a rod to make pellets
step, perhaps directly to molding. Figure on making some really hefty
plastic objects (no point in conserving feedstock if, as last I recall,
recycling centers are not able to give most of the stuff away).
Of course, then I want the spiffy selective membrane tubes to make the
nitrogen, and all anybody wants to sell is the entire packaged nitrogen
system.
--
Cats, coffee, chocolate...vices to live by