Topics

Resin parts


Jon Miller <atsf@...>
 

For those who might wish to make minor parts of resin. for their steam era freight cars, HF now stocks vacuum pumps in two sizes. I doubt these will do any work beyond small parts because price equals quality.
As I don't know the translation of 75 micron/10 Pascal maximum vacuum to inches of mercury.

Jon Miller
AT&SF
For me time has stopped in 1941
Digitrax, Chief/Zephyr systems, JMRI user
NMRA Life member #2623
Member SFRH&MS


Anthony Thompson <thompson@...>
 

Jon Miller wrote:
As I don't know the translation of 75 micron/10 Pascal maximum vacuum to inches of mercury.
That's a quite good vacuum, Jon, far beyond what's needed for resin casting. And those microns? They are micrometers of mercury, so convert them into inches and you have it. It's less than one 10,000th.

Anthony Thompson
Dept. of Materials Science & Engineering
University of California, Berkeley
thompsonmarytony@sbcglobal.net


Anthony Thompson <thompson@...>
 

I wrote:
That's a quite good vacuum, Jon . . . It's less than one 10,000th.
Stopped typing too soon. I should have said "one 10,000th of an atmosphere."

Anthony Thompson
Dept. of Materials Science & Engineering
University of California, Berkeley
thompsonmarytony@sbcglobal.net


Allen Cain <allencain@...>
 

For those of us in the "slow" corner, who is "HF" that you referred to that
has the vacuum pump?



Thanks,



Allen Cain


Earl T. Hackett <hacketet@...>
 

That would be Harbor Freight, importer of cheap Chinese stuff. The
pumps mentioned are intended for HVAC use, typically to pump down AC
systems prior to loading with working fluid or gas. They don't take
well to contamination and you will have a lot of contaminant coming
out of the resin at those vacuum levels. A far better pump for
casting is a Welch/Sargent Douseal pump - you may remember them from
your old high school physics or chemistry class. New they cost
between $2000 and $3000, but you can readily find used ones for about
$300. They are easy to rebuild and with no plastic or rubber seals in
the vacuum path, they tolerate contaminants very well. They are
continuous duty pumps, built from BIG hunks of steel (mine weighs in
at about 100 lbs), and will run for hours without problems.

I used RTV silicone caulk to attach a 6" PVC pipe union to some 1/2"
aluminum plate and to form a seal to some 1" thick acrylic sheet for a
see through top. A needle valve in the top allows me to control
vacuum level during resin degassing. If anyone wants details on how
to set up a resin vacuum casting system, contact me off line.

--- In STMFC@yahoogroups.com, "Allen Cain" <allencain@...> wrote:

For those of us in the "slow" corner, who is "HF" that you referred
to that
has the vacuum pump?


Westerfield <westerfield@...>
 

I second Earl's advice. That's precisely the pump that I use. Even so, contaminants can readily clog even those. We bought a second pump because one was always failing. We solved the problwm by using a tank filled with oil with a standpipe through which the air was pumped, removing possible impurities before thay reached the pump. - Al Westerfield

----- Original Message -----
From: Earl T. Hackett
To: STMFC@yahoogroups.com
Sent: Sunday, December 14, 2008 8:17 AM
Subject: [STMFC] Re: Resin parts


That would be Harbor Freight, importer of cheap Chinese stuff. The
pumps mentioned are intended for HVAC use, typically to pump down AC
systems prior to loading with working fluid or gas. They don't take
well to contamination and you will have a lot of contaminant coming
out of the resin at those vacuum levels. A far better pump for
casting is a Welch/Sargent Douseal pump - you may remember them from
your old high school physics or chemistry class. New they cost
between $2000 and $3000, but you can readily find used ones for about
$300. They are easy to rebuild and with no plastic or rubber seals in
the vacuum path, they tolerate contaminants very well. They are
continuous duty pumps, built from BIG hunks of steel (mine weighs in
at about 100 lbs), and will run for hours without problems.

I used RTV silicone caulk to attach a 6" PVC pipe union to some 1/2"
aluminum plate and to form a seal to some 1" thick acrylic sheet for a
see through top. A needle valve in the top allows me to control
vacuum level during resin degassing. If anyone wants details on how
to set up a resin vacuum casting system, contact me off line.

--- In STMFC@yahoogroups.com, "Allen Cain" <allencain@...> wrote:
>
> For those of us in the "slow" corner, who is "HF" that you referred
to that
> has the vacuum pump?
>


Jon Miller <atsf@...>
 

I agree with both Al and Earl. As I said these would not be for production or even 100's of items. It's a cheap solution for the modeler who wants to do just a few items and is tired of bubbles in the work. 60 bucks is cheap. Even cheaper is buy a pressure tank (HF sells them cheap also) and use your compressor to make pressure castings. Tom Madden showed me how to do this and it works extremely well. No high pressure, about 40 psi works.

Jon Miller
AT&SF
For me time has stopped in 1941
Digitrax, Chief/Zephyr systems, JMRI user
NMRA Life member #2623
Member SFRH&MS


Schuyler Larrabee
 

-----Original Message-----
From: Earl T. Hackett

I used RTV silicone caulk to attach a 6" PVC pipe union to some 1/2"
aluminum plate and to form a seal to some 1" thick acrylic sheet for a
see through top. A needle valve in the top allows me to control
vacuum level during resin degassing. If anyone wants details on how
to set up a resin vacuum casting system, contact me off line.
And

-----Original Message-----

I agree with both Al and Earl. As I said these would not be for
production or even 100's of items. It's a cheap solution for the modeler
who wants to do just a few items and is tired of bubbles in the work. 60
bucks is cheap. Even cheaper is buy a pressure tank (HF sells them cheap
also) and use your compressor to make pressure castings. Tom Madden showed
me how to do this and it works extremely well. No high pressure, about 40
psi works.
So, here we have two great offers. What's the prospect of these being written up, at least in
outline form, and put in the files area?? Both are likely interesting to some of us, and it saves
each of you sending multiple emails to respond to individual requests.

SGL


Mark
 

Sounds like a great idea SGL. I beleive some of us would like to make castings, I have thought of it several times.
 
Sincerely, Mark Morgan MEM

--- On Sun, 12/14/08, Schuyler Larrabee <schuyler.larrabee@verizon.net> wrote:

From: Schuyler Larrabee <schuyler.larrabee@verizon.net>
Subject: RE: [STMFC] Re: Resin parts
To: STMFC@yahoogroups.com
Date: Sunday, December 14, 2008, 6:27 PM







-----Original Message-----
From: Earl T. Hackett

I used RTV silicone caulk to attach a 6" PVC pipe union to some 1/2"
aluminum plate and to form a seal to some 1" thick acrylic sheet for a
see through top. A needle valve in the top allows me to control
vacuum level during resin degassing. If anyone wants details on how
to set up a resin vacuum casting system, contact me off line.
And

-----Original Message-----

I agree with both Al and Earl. As I said these would not be for
production or even 100's of items. It's a cheap solution for the modeler
who wants to do just a few items and is tired of bubbles in the work. 60
bucks is cheap. Even cheaper is buy a pressure tank (HF sells them cheap
also) and use your compressor to make pressure castings. Tom Madden showed
me how to do this and it works extremely well. No high pressure, about 40
psi works.
So, here we have two great offers. What's the prospect of these being written up, at least in
outline form, and put in the files area?? Both are likely interesting to some of us, and it saves
each of you sending multiple emails to respond to individual requests.

SGL


Lawrence Rast
 

Jack Consoli's "Modeling the Pennsylvania Railroad's Gondola Fleet,
Part 18-2 – The G28 Class Gondola Variants," which appeared in the
April 2008 "Keystone Modeler" featured a discussion of resin casting
and showed his homemade vacuum chamber. It may be found at:

http://prrths.com/Keystone%20Modeler/Keystone_Modeler_PDFs/TKM%20No.%2057%2004-08%20PDF.pdf

Best,
Lawrence Rast

On Sun, Dec 14, 2008 at 7:03 PM, Mark Morgan <bnonut@yahoo.com> wrote:
Sounds like a great idea SGL. I beleive some of us would like to make
castings, I have thought of it several times.

Sincerely, Mark Morgan MEM

--- On Sun, 12/14/08, Schuyler Larrabee <schuyler.larrabee@verizon.net>
wrote:

From: Schuyler Larrabee <schuyler.larrabee@verizon.net>
Subject: RE: [STMFC] Re: Resin parts
To: STMFC@yahoogroups.com
Date: Sunday, December 14, 2008, 6:27 PM

-----Original Message-----
From: Earl T. Hackett

I used RTV silicone caulk to attach a 6" PVC pipe union to some 1/2"
aluminum plate and to form a seal to some 1" thick acrylic sheet for a
see through top. A needle valve in the top allows me to control
vacuum level during resin degassing. If anyone wants details on how
to set up a resin vacuum casting system, contact me off line.
And

-----Original Message-----

I agree with both Al and Earl. As I said these would not be for
production or even 100's of items. It's a cheap solution for the modeler
who wants to do just a few items and is tired of bubbles in the work. 60
bucks is cheap. Even cheaper is buy a pressure tank (HF sells them cheap
also) and use your compressor to make pressure castings. Tom Madden showed
me how to do this and it works extremely well. No high pressure, about 40
psi works.
So, here we have two great offers. What's the prospect of these being
written up, at least in
outline form, and put in the files area?? Both are likely interesting to
some of us, and it saves
each of you sending multiple emails to respond to individual requests.

SGL

[Non-text portions of this message have been removed]


Earl T. Hackett <hacketet@...>
 

This is a bit OT for this group - it would be more appropriate for the
Scratchbuilding group, but with the permission of the moderator I'll
stick it in the files section. One note however, my techniques are
intended for very small scale production of parts, I don't need many
of them, but I expect them to be archival. So although the materials
I use are readily available and inexpensive, they are not commonly
used by modelers.

--- In STMFC@yahoogroups.com, "Schuyler Larrabee"
<schuyler.larrabee@...> wrote:
So, here we have two great offers. What's the prospect of these
being written up, at least in
outline form, and put in the files area?? Both are likely
interesting to some of us, and it saves
each of you sending multiple emails to respond to individual
requests.

SGL