Date   

Re: Some thoughts on resin warping & shrinkage

Walter M. Clark
 

--- In STMFC@yahoogroups.com, "Tom Madden" <tgmadden@...> wrote:

Can't offer much in the way of solutions to this very interesting
set of problems, but if you'd care to consider some possibly useful
insights, read on….. (Most of you know a lot of this already, but
it's good to get it all down in one place.)<SNIP>.

Thanks for your attention!

Tom Madden
So, Tom and the rest who have commented on this topic, it seems there
are two additional things I need to do to the resin kits before I
build them.

First, at least for the larger pieces such as roof, ends, side, doors
(maybe) and floors/underframes, heat to about 150 F and hold at that
temperature for a couple of hours before matching/adjusting major
dimensions at the start of assembly (which is a problem because I
don't have an oven that will hold that low a temperature. Would it
work to get the oven up to that temperature, established with an oven
thermometer, turn off the gas and put the kit pieces on a sheet of
glass slid into the oven on the bottom rack, then watch the
temperature and when it drops too low turn on the oven for a little
while to bring the temperature back up? Or would that take a chance
on igniting the resin castings? I don't need a resin smoke bomb in
the oven; my wife's patience only stretches so far).

Second, glue braces inside the sides to remind the sides they are
supposed to stay flat. How about if I use a heavier brass H or
channel along the lower portion of the side and a lighter brass angle
near the top? Would that both keep the sides flat and add weight,
concentrated near the bottom so the car doesn't get top heavy? Of
course I need to be sure the final assembly including trucks, couplers
etc. isn't too heavy, but that is easy to handle.

Of course open top cars wouldn't receive the inner bracing. Would
that really matter too much since hoppers and gondolas don't get too
far from the erecting floor before becoming bent, battered and abused
in service (just don't let it get so bad that it becomes a caricature
and not a representation).

So, what am I missing/where did I go wrong/what suggestions for
improvement can you give me?

Walter M. Clark
Time stopped in November 1941
Riverside, California


Re: MP 34113-34262

Ed Hawkins
 

On Jul 23, 2007, at 9:36 PM, Brian J Carlson wrote:

I'm building the Sunshine 2005 Naperville gift, a mini-kit for the MP
34113-34262 boxcars. The instructions say to paint the car entirely
oxide
red. I wanted to check and make sure this includes the roof and
running
board. Thanks.
Brian J Carlson P.E.
Cheektowaga NY
Brian,
For new cars, according to the AC&F paint specs the sides, ends, and
roofs were painted Sherwin Williams Brown (paint chip matches 50/50 mix
of Floquil Southern Freight Car Brown (175) and Box Car Red (074), at
least with the older formulas of Floquil paint. Underframes, trucks and
placards were black. The cars had Apex Tri-Lok running boards and Ajax
hand brakes. Any repaints would have received the same paint scheme,
however, the cars received "Route of the Eagles" slogans and 42"
buzzsaw emblems if repainted anytime after mid-1949. Also, the color
changed with more red during the 1950s.
Regards,
Ed Hawkins


SP B-70-1 thru -5: Doors and Decals in HO?

Kurt Laughlin <fleeta@...>
 

Can anyone recommend a source for 9 ft Youngstown plug doors and decals for these cars in HO?

TIA,
KL


MP 34113-34262

Brian J Carlson <brian@...>
 

I'm building the Sunshine 2005 Naperville gift, a mini-kit for the MP
34113-34262 boxcars. The instructions say to paint the car entirely oxide
red. I wanted to check and make sure this includes the roof and running
board. Thanks.
Brian J Carlson P.E.
Cheektowaga NY


Re: Freight Car Parts

Schuyler Larrabee
 

I was thinking about the comments regarding copyrights on the Cyc pages, and how we'd need to get
permissions to use those pages. Why do we need those? Certainly there are sufficient photographs
among the collections of photographs available to this group to provide illustrations (with a credit
line if desired) to very amply illustrate a Wiki page as Tim O'Connor suggested. In fact, there was
a remark that the same old illustrations appeared for decades in the Cycs, which did not refliect
the evolution of the product(s). Carefully selected photos could provide exactly that documentation
of the evolving product. To assist those who need the Original Source, the year and page can be
cited as a source of the base information, but nothing from that page need be copied.


Ummm, no, I'm not volunteering to do this . . .

SGL
La vita e breve, mangiate prima il dolce!


Didn't MR have an article about a year ago in which they showed photos
of the more common freight car ends, roofs, etc.?

regards,
Andy Miller

-----Original Message-----
From: jerryglow2

As Richard already commented, there isn't but Carbuilders Cyclopedias
contain builders plugs on their own equipment plus a section on parts
details. Not all inclusive nor that readily available.

Jerry Glow

--- In STMFC@yahoogroups.com <mailto:STMFC%40yahoogroups.com>
, "Paul & Bernice Hillman"
<chris_hillman@...> wrote:

Is there a book which has attempted to contain all of the various
freight car component descriptions, such as Murphy roofs, Duryea
underframes, Youngstown doors, etc., etc., all the myriad types of
ends, doors, etc. which are talked about/used in the various car
constructions?

I mean a book which describes these various components without
necessarily going into specific cars themselves?

I know that this info can be gleaned "piece-meal" from the
multitude
of
construction articles and books, but I think it would be an
excellent

quick-reference to these components.

Thanks, Paul Hillman


Re: Freight Car Parts - You Too Can Be an Expert :-)

Charlie Vlk
 

The idea of a Model Railroader's Car Builder's Cyclopedia for common Freight Car Components is not a bad one.....
I know we have the RPC and other fine publications but they generally focus on a particular car or segment of equipment.
The real Cycs don't use our nomenclature, never having had to worry about "phases" or evolutions in design that we do.
Might be a good project for one of our Authorities that also do publications....
Charlie Vlk


Some thoughts on resin warping & shrinkage

Tom Madden <tgmadden@...>
 

Can't offer much in the way of solutions to this very interesting
set of problems, but if you'd care to consider some possibly useful
insights, read on….. (Most of you know a lot of this already, but
it's good to get it all down in one place.)

As Pierre says, styrene and cured urethane resin are two different
materials. They have different physical properties, and they respond
to heat in entirely different ways.

Styrene is a thermoplastic material; it can be re-melted and formed
into new shapes many times over. The heat necessary to melt styrene
is applied externally, and styrene solidifies when it cools. Any
shrinkage is due entirely to its coefficient of thermal expansion.
If the injection mold is held at a fixed temperature and the cycle
time is locked in, all parts will match exactly. Subsequent heating
and cooling of a styrene part will not change its physical
properties or dimensions. (As long as you don't melt it!)

Urethane resin is a thermosetting material; two liquid components
(base and catalyst) are mixed together and contained in a mold until
the casting cures. The heat needed to cure the casting is generated
internally, and comes from the chemical reaction between base and
catalyst. The casting solidifies at an elevated temperature when the
reaction "trips" and massive cross-linking occurs. THE TEMPERATURE
AT WHICH THIS TAKES PLACE DEPENDS ON THE AMOUNT OF MATERIAL USED,
AND THE GEOMETRY OF THE PART.

Castings that cure at higher temperatures exhibit greater shrinkage
than castings that cure at lower temperatures. Makes sense, because
they have further to go to get back to room temperature, and
coefficient of thermal expansion is a harsh mistress!

But, you say, that should only be true with different materials.
Surely a given material will always react the same way, release the
same amount of heat energy, and the castings will all cure at the
same temperature, n'est pas??

Mais non, mon ami! Yes, the energy released per unit of material is
always the same, but if the casting is very thin, a lot of that heat
will be dissipated into the mold and be unavailable to cure the
casting. Thin castings cure at lower temperatures and as a result
exhibit lower shrinkage. But they are not fully cured – i.e. not
fully cross-linked. (That's why a casting can be rock-hard, while
the flash surrounding it is still sticky.)

Which brings us to the second source of urethane casting shrinkage:
post-curing of incompletely cured castings, which I suspect is the
cause of our problems. The specs for fully-cured urethane are
derived from thick (from our point of view) slab castings, either
1/8" or 1/4" thick and large enough so that the mix reaches its
maximum attainable temperature when the reaction trips. The
percentage of heat dissipated into the mold is relatively small, so
the resulting samples are fully cured and fully cross-linked. A
freight car side around 0.040" thick has few geometrical
similarities with such a slab, even if it contains the same amount
of resin.

The problem comes because the urethane really wants to be fully
cured. Heating castings to flatten them will help, but if no
additional heat is supplied, the castings will continue to cure at
room temperature, even if it takes many (sometimes many, many)
months. This additional cure is really additional cross-linking, and
as this proceeds the molecules in the castings are pulled closer
together. And the castings continue to shrink. It shouldn't take too
much imagination to visualize an assembled resin freight car body:
slab roof, which is a pretty thick casting to begin with and is most
likely fully cured; two ends which are relatively small compared to
the roof; and two sides, still needing to shrink and will do so with
very noticeable results if they are only restrained at the edges.

One more factor needs to be considered, then we'll wrap up this
exposition. And that is Heat Deflection Temperature, or HDT. This is
the spec'd temperature at which cured urethane deforms, and it is
typically quoted in multiple ways. One might be: "135F (24 hrs RT
cure); 150F (24 hrs RT cure followed by 24 hrs @ 180F)". In this
case the shrinkage would be quoted as "0.001" per inch (RT cure
only); 0.003" per inch (post-cured)". Parts have to be supported
during post-cure so they don't deform.

There are a number of implications to all this. First, you know none
of our hobby resin kit providers are post-curing their castings in
any meaningful way. This is good, because it leaves room for us to
heat and flatten castings when necessary. In fact, it might be
useful to heat large thin castings for a couple hours at 150F or so
as a matter of course, to make post-assembly differential shrinkage
less of an issue. You'd do this before sizing the parts, because
post-curing drives castings to a higher state of cure and introduces
additional shrinkage. Secondly, you cannot repeatedly heat and
reheat castings to modify their shapes and expect them to respond
the same way every time. It's that "higher state of cure" thing
again. Third, Tim's suggestion of bonding true structural members to
the backside of thin castings is a good one. Properly done, the
castings may still want to shrink, but they won't be able to – at
least, not so much as to deform. Fourth, the above applies more to
flat cast parts than to one piece bodies. Yes, all of that can
affect one piece bodies to some extent, but more likely causes of
deformed one piece bodies are removing castings from molds too soon
(which can stretch parts irrevocably), or inadequate support for the
castings when they are shipped or stored. Keeping the HDT in mind,
you'd like the castings in a resin kit to be packed so as to survive
being left in the back of a UPS truck sitting on an asphalt parking
lot in El Centro, CA, over the 4th of July weekend. Think that's
ridiculous? You haven't been in my attic recently. I have all sorts
of styrene kits surviving nicely up there, but all my resin kits are
on shelves in my workshop.

Personally, I prefer thicker sides so deformation isn't an issue.
But urethane resin is expensive, and minimizing the amount used is
one way of controlling costs – so long as manufacturer and consumer
are aware of the problems.

Thanks for your attention!

Tom Madden


Re: Freight Car Parts

Paul Hillman
 

--- In STMFC@yahoogroups.com, Ed Hawkins <hawk0621@...> wrote:
********************************************************************
Richard,

Yes,the publishers are listening. However,I will volunteer some
information about Volume 10 of RP CYC that unquestionably contained the
very best source of hand brake information ever assembled in one place
(59 pages of comprehensive material authored by Pat Wider). Yet this
book has been our poorest seller out of 15 books published to date.
*********************************************************************

Hi Ed,

I originally asked this question to the group about such a book, and I
would have hoped that such a comprehensive book WOULD contain a section
on handbrakes.

I think that, however, the subject of handbrakes alone yields much less
interest than the more major car-parts such as roofs, ends, doors,
underframes, trucks, etc. Yet handbrakes are also a major-proto detail.

It could be suggested that "booklets" be produced that cover each car-
part; IE) one for doors, one for roofs, etc., etc. But an all
encompassing publication should attract more buyers who would find the
perhaps "lesser details" an added bonus to a more extensive publication.

In fact, this was my original realization, that all/many of these
detail-facts can be procured through the accumulation by one's self, of
multiple articles and publications, but not in one book.

If there were however, "booklets" for each component, I myself might
abstain from purchasing some of them until I thought I might need them.
Yet I WOULD purchase such a "complete" book and get the "bonus" of all
the other details as well. (Perhaps some of which I hadn't even thought
about.)

I think that there would be a good market for such a complete book as
per this suggestion. In the case that one is in the making, someone put
me down on the list of buyers.

Thanks, Paul Hillman


Re: Shellac

Jon Miller <atsf@...>
 

ScaleCoat lasted better than Floquil<
Better than "new" Floquil. I have an old square 2 oz bottle of Floquil boxcar red (probably 30 years old) that still works as good as the day it was made. Modern safely formulas are what makes paint go bad.

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


Shellac

Justin Kahn
 

Yes, but how much shellac is one likely to use in a year? Hardly worth keeping it on hand if most of it will end up being thrown out. One of the reasons I like the acrylic-based paints, such as Badger: they last a lot longer on the shelf for those of us who don't do a lot of painting. ScaleCoat lasted better than Floquil, but a large part of my train budget went toward replacing Floquil paint when that was most of what was available.
Jace Kahn

Your problem was that you used shellac that was too old. Most shellac has a
shelf life of one year, and the date is always on the can. Failure to dry
is the issue with old shellac. I have frequently used shellac and get very
good results with it. It dries quickly and is easy to clean up.

Nearly thirty years ago, when I first changed over to O scale and had
both

larger surfaces to deal with and a greater impetus for better-detail, I
tried shellac. It took several years for it to really dry. Never again.
The Deft (e.g., "lacquer-based sealer") dries in less than an hour.
JGGK
<harumd@...> wrote:
As to sealing wood cars, I kept hearing about "lacquer-based sanding
sealer" without anyone suggesting a source
I used to use Scalecoat which worked just fine. It has some kind of
particles in it besides the lacquer. I think it was recommended on
Q'Craft instruction sheets.

I've also seen shellac recommended to seal wood.

Being frugal and having access to chemicals (and being a seat of the
pants chemist) I dissolved Ambroid cement in MEK and used that.

Wood really sucks up both formaulations by capillary action.

Ed
_________________________________________________________________
Don't get caught with egg on your face. Play Chicktionary!� http://club.live.com/chicktionary.aspx?icid=chick_hotmailtextlink2


Re: Resin warping

Douglas Harding <dharding@...>
 

Denny, if after your arrival, you need something. Contact me, I may have it
or be able to help.

Doug Harding
www.iowacentralrr.org

No virus found in this outgoing message.
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7:02 PM


Re: Freight Car Parts

Ed Hawkins
 

On Jul 23, 2007, at 12:24 PM, Richard Brennan wrote:

Sounds like a great "project" for a future issue of either RP
Cyclopedia or Prototype Railroad Modeling Journal!
I think this would become an indispensable reference. Publishers...
are you listening?
Richard,
Yes, the publishers are listening. However, I will volunteer some
information about Volume 10 of RP CYC that unquestionably contained the
very best source of hand brake information ever assembled in one place
(59 pages of comprehensive material authored by Pat Wider). Yet this
book has been our poorest seller out of 15 books published to date.
EVERY freight car placed in interchange service had a hand brake and
it's an item that applies across the board, but a lot of people that
normally buy RP CYC didn't purchase this book. The "hard-core" freight
car enthusiasts liked it (i.e., probably many from the STMFC), but it's
apparent that the 59 pages of hand brakes didn't justify the purchase
of the book by others who are less interested in this level of detail.
Would the same hold true for other comprehensive articles on freight
car components such as running boards, ends, and box car doors?

These questions always stick in our minds when we make decisions on the
content of future books. Researching and publishing the information is
one thing. Selling books with subject matter that's of interest to
enough people that will yield a decent monetary reward for the effort
involved is yet another.

It's important to keep in perspective that people in the STMFC are
relatively few in number when considering the audience that may
purchase a book having subject matter of this type. It's sorta like a
TV show that received great honor from constituents within the TV
broadcast community for its technical merits and important message to
society, but was canceled due to lousy ratings from viewers.
Regards,
Ed Hawkins


Re: M&StL USRA Box Cars

rockroll50401 <cepropst@...>
 

I looked at my photos.
I have one of a 22000 w/fascia
5 of the 25000, 1 w/fascia
1 of the 51000 w/fascia
Looks like it wasn't installed on all rebuilds

Gene Green gives no original owners for the 25300-25898

The 52000 were rebuilt from the CNW reefers.

It is possible that the xBLE cars were rebuild to look like USRA DS
cars in number series 50300-50348 (25 cars)

Clark Propst formally of Marshalltown IA



--- In STMFC@yahoogroups.com, Richard Hendrickson <rhendrickson@...>
wrote:

On Jul 23, 2007, at 1:27 PM, timboconnor@... wrote:


Propst, Richard. I think Probst was a beer. :-)
Right you are, Tim, and thanks for the correction. Probst was a
beer,
whereas Propst is a beer consumer.

Richard Hendrickson




Re: Resin warping

pierreoliver2003 <pierre.oliver@...>
 

Richard,
Be very careful with this idea. Styrene and resin have very different
rates of expansion and contraction.
I've not had the kinds of problems you're describing.
Pierre Oliver

--- In STMFC@yahoogroups.com, Richard Brennan <brennan8@...> wrote:

At 11:38 7/23/2007, Armand Premo wrote:
Two of my most recently built cars warped after the car was
finished.I suspect that this was due to the very thin castings.
Normally I
put interior bracing, but these were the doors. Any thoughts?
Hmm... I had a similar thing happen.
It looks like I assembled the car at 30,000 feet... and now at sea
level, the sides have "imploded" (concave warp).

These were -very- thin car side castings.
I was thinking I would need to give it the icebox treatment to
de-bond the ACC... then laminate the sides to something like sheet
styrene.

Any ideas? Will the bi-material lamination cause any problems?


--------------------
Richard Brennan - San Leandro CA
--------------------


Re: M&StL USRA Box Cars

Richard Hendrickson
 

On Jul 23, 2007, at 1:27 PM, timboconnor@comcast.net wrote:


Propst, Richard. I think Probst was a beer. :-)
Right you are, Tim, and thanks for the correction. Probst was a beer,
whereas Propst is a beer consumer.

Richard Hendrickson


Re: M&StL USRA Box Cars

Tim O'Connor
 

Propst, Richard. I think Probst was a beer. :-)

-------------- Original message ----------------------
From: Richard Hendrickson <rhendrickson@opendoor.com>
I got exactly the information I needed, thanks to Joe Binish, Ben Hom,
Ted Culotta, Clark Probst, Richard Berry, and Doug Harding. Gawd, I
love this group!


Re: M&StL USRA Box Cars

Richard Hendrickson
 

I got exactly the information I needed, thanks to Joe Binish, Ben Hom,
Ted Culotta, Clark Probst, Richard Berry, and Doug Harding. Gawd, I
love this group!

Richard Hendrickson


Re: Resin warping

Tim O'Connor
 

Sheet styrene? Nope. You need something more rigid -- a H
or I beam, or heavy strip styrene, glued on a narrow edge. But
basswood and pine are cheaper.

You can bond basswood or pine to polyurethane resin with
epoxy cement. This will give your car sides great strength and
resistance to temperature induced warping. Another technique
is interior bulkheads -- in fact these came with the Sunshine
M53 kit, so the body (a thin casting) would have some strength.

You can also bond brass tube to the inside walls with epoxy.
This will not warp.

Tim O'Connor

-------------- Original message ----------------------
From: Richard Brennan <brennan8@earthlink.net>
At 11:38 7/23/2007, Armand Premo wrote:
Two of my most recently built cars warped after the car was
finished.I suspect that this was due to the very thin castings. Normally I
put interior bracing, but these were the doors. Any thoughts?
Hmm... I had a similar thing happen.
It looks like I assembled the car at 30,000 feet... and now at sea
level, the sides have "imploded" (concave warp).

These were -very- thin car side castings.
I was thinking I would need to give it the icebox treatment to
de-bond the ACC... then laminate the sides to something like sheet styrene.

Any ideas? Will the bi-material lamination cause any problems?


40' C&NW DD riveted PS-1 Boxcar

Andy Carlson
 

Last week I found a former C&NW riveted side 40' PS-1 boxcar in a RR facility in North Western Nebraska. It was unusual in that the double youngstown doors were of the 6/6/6 rib pattern, not the expected and common as dirt 5/6/6 patern Improved Youngstown doors. The right side door was an 8 foot door, the left was a 7 1/2' door with an additional 1/2 foot extension resembling a removable center door post. The ends appear to be standard PS-1 parts. Were the doors modified after being placed into MoW service. I have posted a picture in the photo files section. Thanks,
-Andy Carlson
Ojai CA


Re: Resin warping

Richard Brennan <brennan8@...>
 

At 11:38 7/23/2007, Armand Premo wrote:
Two of my most recently built cars warped after the car was
finished.I suspect that this was due to the very thin castings. Normally I
put interior bracing, but these were the doors. Any thoughts?
Hmm... I had a similar thing happen.
It looks like I assembled the car at 30,000 feet... and now at sea level, the sides have "imploded" (concave warp).

These were -very- thin car side castings.
I was thinking I would need to give it the icebox treatment to de-bond the ACC... then laminate the sides to something like sheet styrene.

Any ideas? Will the bi-material lamination cause any problems?


--------------------
Richard Brennan - San Leandro CA
--------------------

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