Train of Thought- Sanding resin flash, or: avoiding bloody finger tips.


Denny Anspach <danspach@...>
 

Friends, I am once again engaging in my usual summer push-on-the-porch to build at least several fine kits, some really challenging, and others merely enjoyable. I have no grand plan or scheme, but simply choose those projects that catch my fancy and interest.

One of my current projects is a thoroughly delightful Westerfield Milwaukee Road 36' drop-door stock car kit, and as one might expect, the exquisite flat sides with their myriads of slats and fine bracing are all laid out in high relief on a relatively thick tough slab of resin. Now, the entire project depends upon cleaning out all flash between these fine slats and braces without collateral damage, the produced spaces to be squarely and smoothly cleared. In this regard, all know what to do: sand the backs of these sides until the flash between the slats becomes so thin that it can be easily cleaned out with the hosts of various sharp instruments that are right at hand (none of which really fit, or do the job!).

So the sanding of these large pieces begin: a segment of 220 grit wet-or-dry sandpaper is laid out flat; the side is placed on its back; and with fingers spread-eagled the length and width of the slide, the side is moved back and forth with sufficient pressure to engage the cutting sand paper granules, but not enough to grab the sandpaper and bunch it up with the creases that will only cause future problems.

Well, after a considerable length of time (I count to 100 slowly, with about three swipes per count per bout of sanding), I take a look and- I find that the flash is indeed minutely being removed, but primarily only under the tips of my "light" fingers. I change the position of my fingers, but I do not get very far because the sand paper is now loading up. I wash the sandpaper with a drop of detergent, dry it on a tea towel, and then get back to sanding. I rotate the side; I try to flatten my finger tips; I change my finger positions; I load up again; I wash again, and so on. Finally, I detect that the the bloom is off the rose on this once-fresh sandpaper (resin must be harder than I would imagine), and new sand paper is called for.

Now, I steal the small broiler pan out of the toaster over, fill it with detergent water, submerge the sandpaper, and commence sanding again, this time underwater. Things move faster (the paper is now self cleaning), and at least an elapsed 1/2 hour each after starting, finally the sides are becoming thin enough so that the flash between the slats and braces is thin enough to attack with my sharp sticks. However, at the same time, the sides are also becoming thin enough to become somewhat delicate to the handling that is still necessary.

But wait! The much thinned flash must still be removed so that the slats and braces have clean sharp edges, both in fact and in perception. This is undertaken with my principal sharp stick: a #11 Xacto blade whose point has been specially honed on an Arkansas stone, and whose "square" backside has also been flat-sharpened- i.e. the 90º corners are also made as sharp as possible so that with only only the slightest tip, the backside will cut -actually scrape- just about as well as the knife edge on the other side. With this wonder tool, and a variety of stiff brushes, pokers, etc. and about an expended time of @hour, at last the exquisite, now fully-fenestrated sides are ready for their ends to be mitered to fit the car ends (also mitered).

I write this all up so that I can learn from others how THEY handle this relatively common but time consuming and tedious situation. My finger prints have probably been erased from my fingers during previous bouts of such resin flash sanding with much smaller pieces, the skin of the fingers being freshly sanded -bloody even- along with the target resin part.

I will say that demanding kits like this make me realize once again what a fulfilling delightful hobby this is!

Denny










H-mmm.
Denny S. Anspach, MD
Okoboji, Iowa


Bruce Smith
 

Denny Anspach <danspach@...> 08/19/10 11:08 PM >>>
I write this all up so that I can learn from others how THEY handle
this relatively common but time consuming and tedious >situation. My
finger prints have probably been erased from my fingers during previous
bouts of such resin flash sanding with >much smaller pieces, the skin of
the fingers being freshly sanded -bloody even- along with the target
resin part.

Denny,

220? Show some courage, man! <VBG> I start with 90 grit Norton 3X
sandpaper. This stuff is amazing as it lasts 3x longer than regular
paper.

Sand in a figure 8 motion, turning the work every 10 strokes or so

Check often, and don't get distracted... or you WILL sand through your
work - total work time, about 3-5 minutes max.

When you get close, shift to something in the high 100's to low 200's
for grit (now is the time for that 220).

When the flash in the slats is basically falling out, grit blast it off.

And - I know you know this, but others may not - wear respiratory
protection (a dust mask) as resin dust is not harmless.

Regards
Bruce

Bruce Smith
Auburn, AL


Al and Patricia Westerfield <westerfield@...>
 

Denny - We once got a request for new stock car sides from a dentist who used a belt sander to remove the flash (and everything else. - Al Westerfield

----- Original Message -----
From: Denny Anspach
To: STMFC List
Sent: Thursday, August 19, 2010 9:04 PM
Subject: [STMFC] Train of Thought- Sanding resin flash, or: avoiding bloody finger tips.



Friends, I am once again engaging in my usual summer push-on-the-porch to build at least several fine kits, some really challenging, and others merely enjoyable. I have no grand plan or scheme, but simply choose those projects that catch my fancy and interest.

One of my current projects is a thoroughly delightful Westerfield Milwaukee Road 36' drop-door stock car kit, and as one might expect, the exquisite flat sides with their myriads of slats and fine bracing are all laid out in high relief on a relatively thick tough slab of resin. Now, the entire project depends upon cleaning out all flash between these fine slats and braces without collateral damage, the produced spaces to be squarely and smoothly cleared. In this regard, all know what to do: sand the backs of these sides until the flash between the slats becomes so thin that it can be easily cleaned out with the hosts of various sharp instruments that are right at hand (none of which really fit, or do the job!).

So the sanding of these large pieces begin: a segment of 220 grit wet-or-dry sandpaper is laid out flat; the side is placed on its back; and with fingers spread-eagled the length and width of the slide, the side is moved back and forth with sufficient pressure to engage the cutting sand paper granules, but not enough to grab the sandpaper and bunch it up with the creases that will only cause future problems.

Well, after a considerable length of time (I count to 100 slowly, with about three swipes per count per bout of sanding), I take a look and- I find that the flash is indeed minutely being removed, but primarily only under the tips of my "light" fingers. I change the position of my fingers, but I do not get very far because the sand paper is now loading up. I wash the sandpaper with a drop of detergent, dry it on a tea towel, and then get back to sanding. I rotate the side; I try to flatten my finger tips; I change my finger positions; I load up again; I wash again, and so on. Finally, I detect that the the bloom is off the rose on this once-fresh sandpaper (resin must be harder than I would imagine), and new sand paper is called for.

Now, I steal the small broiler pan out of the toaster over, fill it with detergent water, submerge the sandpaper, and commence sanding again, this time underwater. Things move faster (the paper is now self cleaning), and at least an elapsed 1/2 hour each after starting, finally the sides are becoming thin enough so that the flash between the slats and braces is thin enough to attack with my sharp sticks. However, at the same time, the sides are also becoming thin enough to become somewhat delicate to the handling that is still necessary.

But wait! The much thinned flash must still be removed so that the slats and braces have clean sharp edges, both in fact and in perception. This is undertaken with my principal sharp stick: a #11 Xacto blade whose point has been specially honed on an Arkansas stone, and whose "square" backside has also been flat-sharpened- i.e. the 90º corners are also made as sharp as possible so that with only only the slightest tip, the backside will cut -actually scrape- just about as well as the knife edge on the other side. With this wonder tool, and a variety of stiff brushes, pokers, etc. and about an expended time of @hour, at last the exquisite, now fully-fenestrated sides are ready for their ends to be mitered to fit the car ends (also mitered).

I write this all up so that I can learn from others how THEY handle this relatively common but time consuming and tedious situation. My finger prints have probably been erased from my fingers during previous bouts of such resin flash sanding with much smaller pieces, the skin of the fingers being freshly sanded -bloody even- along with the target resin part.

I will say that demanding kits like this make me realize once again what a fulfilling delightful hobby this is!

Denny

H-mmm.
Denny S. Anspach, MD
Okoboji, Iowa


Pierre <pierre.oliver@...>
 

Doc,
Entertaining read.
As I've said in clinics on building resin kits, the best way to get good at sanding resin castings is to do a string of stock cars. It'll either cure you or kill you.:-)
What I do which helps relieve the tedium and speeds up the process is to use coarser sand paper. 80 or 120 grit. The 80 is reserved for those cases where the flash is very thick. One needs to be very careful about how much material one is removing, but with a little diligence the job can be done fairly quickly. I've yet to sand through a casting.
Which reminds me, it's time to glue more sand paper to plexi for sanding resin. The old sheets are worn out.
Pierre Oliver

--- In STMFC@..., Denny Anspach <danspach@...> wrote:

Friends, I am once again engaging in my usual summer push-on-the-porch to build at least several fine kits, some really challenging, and others merely enjoyable. I have no grand plan or scheme, but simply choose those projects that catch my fancy and interest.

One of my current projects is a thoroughly delightful Westerfield Milwaukee Road 36' drop-door stock car kit, and as one might expect, the exquisite flat sides with their myriads of slats and fine bracing are all laid out in high relief on a relatively thick tough slab of resin. Now, the entire project depends upon cleaning out all flash between these fine slats and braces without collateral damage, the produced spaces to be squarely and smoothly cleared. In this regard, all know what to do: sand the backs of these sides until the flash between the slats becomes so thin that it can be easily cleaned out with the hosts of various sharp instruments that are right at hand (none of which really fit, or do the job!).

So the sanding of these large pieces begin: a segment of 220 grit wet-or-dry sandpaper is laid out flat; the side is placed on its back; and with fingers spread-eagled the length and width of the slide, the side is moved back and forth with sufficient pressure to engage the cutting sand paper granules, but not enough to grab the sandpaper and bunch it up with the creases that will only cause future problems.

Well, after a considerable length of time (I count to 100 slowly, with about three swipes per count per bout of sanding), I take a look and- I find that the flash is indeed minutely being removed, but primarily only under the tips of my "light" fingers. I change the position of my fingers, but I do not get very far because the sand paper is now loading up. I wash the sandpaper with a drop of detergent, dry it on a tea towel, and then get back to sanding. I rotate the side; I try to flatten my finger tips; I change my finger positions; I load up again; I wash again, and so on. Finally, I detect that the the bloom is off the rose on this once-fresh sandpaper (resin must be harder than I would imagine), and new sand paper is called for.

Now, I steal the small broiler pan out of the toaster over, fill it with detergent water, submerge the sandpaper, and commence sanding again, this time underwater. Things move faster (the paper is now self cleaning), and at least an elapsed 1/2 hour each after starting, finally the sides are becoming thin enough so that the flash between the slats and braces is thin enough to attack with my sharp sticks. However, at the same time, the sides are also becoming thin enough to become somewhat delicate to the handling that is still necessary.

But wait! The much thinned flash must still be removed so that the slats and braces have clean sharp edges, both in fact and in perception. This is undertaken with my principal sharp stick: a #11 Xacto blade whose point has been specially honed on an Arkansas stone, and whose "square" backside has also been flat-sharpened- i.e. the 90º corners are also made as sharp as possible so that with only only the slightest tip, the backside will cut -actually scrape- just about as well as the knife edge on the other side. With this wonder tool, and a variety of stiff brushes, pokers, etc. and about an expended time of @hour, at last the exquisite, now fully-fenestrated sides are ready for their ends to be mitered to fit the car ends (also mitered).

I write this all up so that I can learn from others how THEY handle this relatively common but time consuming and tedious situation. My finger prints have probably been erased from my fingers during previous bouts of such resin flash sanding with much smaller pieces, the skin of the fingers being freshly sanded -bloody even- along with the target resin part.

I will say that demanding kits like this make me realize once again what a fulfilling delightful hobby this is!

Denny










H-mmm.
Denny S. Anspach, MD
Okoboji, Iowa


soolinehistory <destorzek@...>
 

--- In STMFC@..., "Al and Patricia Westerfield" <westerfield@...> wrote:

Denny - We once got a request for new stock car sides from a dentist who used a belt sander to remove the flash (and everything else. - Al Westerfield

Imagine what he'd do inside your mouth!

:-(

Dennis


Jack Burgess <jack@...>
 

The YV never had a need to run stock cars so I don't ever see the need to
built a resin stock car kit. But it seems that one of the problems is
getting constant pressure when you are sanding, regardless of the grade of
sandpaper. I once purchased a small sheet of "rubber" at the hardware store
to temporarily stop a leak on a water pipe (the rubber and a pair of
radiator clamps did the job). I wonder if a piece of rubber attached to a
block of wood (with contact cement or double sided tape) could be used in
lieu of your fingers during the sanding operation? The rubber would allow
the block to conform to the surface variations of the resin side and,
hopefully, also let the piece slide back and forth on the sandpaper without
slipping. If that works as envisioned, it would even out the pressure as you
sand.

Just an untried thought...

Jack Burgess
www.yosemitevalleyrr.com


Pierre <pierre.oliver@...>
 

Oh Jack. You don't know what you're missing!
Every resinator should go through the special joy that is stock car kits. :-)
Pierre Oliver

--- In STMFC@..., "Jack Burgess" <jack@...> wrote:

The YV never had a need to run stock cars so I don't ever see the need to
built a resin stock car kit. But it seems that one of the problems is
getting constant pressure when you are sanding, regardless of the grade of
sandpaper. I once purchased a small sheet of "rubber" at the hardware store
to temporarily stop a leak on a water pipe (the rubber and a pair of
radiator clamps did the job). I wonder if a piece of rubber attached to a
block of wood (with contact cement or double sided tape) could be used in
lieu of your fingers during the sanding operation? The rubber would allow
the block to conform to the surface variations of the resin side and,
hopefully, also let the piece slide back and forth on the sandpaper without
slipping. If that works as envisioned, it would even out the pressure as you
sand.

Just an untried thought...

Jack Burgess
www.yosemitevalleyrr.com


Clark Propst
 

Some models come with a square of foam in the box to 'hold' the model during shipment. I've used these foam chunks to 'hold' the sides while sanding.

I made the mistake of telling my operating crew that hogs were shipped in double deck stock cars. I have more Westerfield Milwaukee single deck cars 3 to 1. The crews started giving me crap about having hogs in single deck cars. Finally I emailed Al and asked if he'd make me some double doors. He did. I replaced the doors and redecaled the cars.

The other day they showed me where "Blackstone" is coming out with HOn3 stocks for sheep loading with single doors.....

Clark Propst


Rob & Bev Manley
 

I am working on an A.T.S.F. Westerfield stock car and have been using coarse fingernail boards. You could make these with Gator Board (R) and automotive production paper too.
When I tried my hand at the wonderful world of auto body repair, I used a rubber "block" tool. It has a rectangular footprint with a dome shape on the top. the front and back had a slot with 2 teeth inside the mouth that woukld hold the sandpaper in place without slipping. I have seen these in the body & fender section of the auto parts stores. The trick was to fold the sheet of paper down to a third of its width and insert into the tool. This way you could change the worn side to a new side without running back to get another sheet.

I have also used 280 grit W&D paper double face taped to the blade of an Exacto #17 to clean up those tight spots.

Rob Manley

----- Original Message -----
From: Pierre
To: STMFC@...
Sent: Friday, August 20, 2010 9:30 AM
Subject: [STMFC] Re: Train of Thought- Sanding resin flash, or: avoiding bloody finger tips.



Oh Jack. You don't know what you're missing!
Every resinator should go through the special joy that is stock car kits. :-)
Pierre Oliver

--- In STMFC@..., "Jack Burgess" <jack@...> wrote:
>
> The YV never had a need to run stock cars so I don't ever see the need to
> built a resin stock car kit. But it seems that one of the problems is
> getting constant pressure when you are sanding, regardless of the grade of
> sandpaper. I once purchased a small sheet of "rubber" at the hardware store
> to temporarily stop a leak on a water pipe (the rubber and a pair of
> radiator clamps did the job). I wonder if a piece of rubber attached to a
> block of wood (with contact cement or double sided tape) could be used in
> lieu of your fingers during the sanding operation? The rubber would allow
> the block to conform to the surface variations of the resin side and,
> hopefully, also let the piece slide back and forth on the sandpaper without
> slipping. If that works as envisioned, it would even out the pressure as you
> sand.
>
> Just an untried thought...
>
> Jack Burgess
> www.yosemitevalleyrr.com
>


Jim Pickett
 

Never heard of a dentist using a belt sander inside a patient's mouth.


Jim Pickett

--- On Fri, 8/20/10, soolinehistory <destorzek@...> wrote:


From: soolinehistory <destorzek@...>
Subject: [STMFC] Re: Train of Thought- Sanding resin flash, or: avoiding bloody finger tips.
To: STMFC@...
Date: Friday, August 20, 2010, 8:43 AM


 





--- In STMFC@..., "Al and Patricia Westerfield" <westerfield@...> wrote:

Denny - We once got a request for new stock car sides from a dentist who used a belt sander to remove the flash (and everything else. - Al Westerfield

Imagine what he'd do inside your mouth!

:-(

Dennis


pullmanboss <tcmadden@...>
 

In 2005 I cast 50 of the NP stock car kits marketed by Aaron Gmundsen's Northern Specific Models and did them in closed (2-part) molds to minimize flash. Both sides and the roof were cast in the same mold to make sure all the long parts in a set matched, and the flash was thin enough that you could clear the slots by pushing a drill shank of the appropriate size through from the front and sliding it back and forth. The corners of the slots needed a bit of cleaning with a #11 X-Acto or scalpel blade, and the pushed-through material needed to be broken away with a stiff-bristled brush on the back side, but no sanding was needed. I did these as a demonstration project for Aaron, and to help him fill orders when his own casting methods came up short.

Aaron had alread set his price for the kit so I sold the castings to him at a heavy discount so he could meet it, but it wasn't anything I wanted to continue - at that price. He later turned that kit and his NP flat car - I cast the first 140 of those in 2006 - over to the NP Society. I don't know who's casting them now.

So it can be done. Problem is, we run into that old price bugaboo and the tendency of some in the hobby to complain about a specialty product that they want but which they think, by their standards, is too expensive. Never mind the extra labor, care, skill and engineering that has gone into such a product, and never mind the time savings for the builder when the parts fit properly and need little preparation. You get flailed with the old "why, back when I started I could get an Athearn stock car for $2.98, and you want [high price of your choice] for THAT?!!" argument, and it does get discouraging. So we cast our resin stock car sides with conventional flat casting methods and let the modeler sand away with the hope of ending up with clean sides of uniform thickness. And resin stock cars earn their "difficult" reputations.

But it needn't be that way...

Tom Madden


Pierre <pierre.oliver@...>
 

At the risk of being put in jail;
Dentists prefer rotational action, thus a router would be more in order
Pierre Oliver

--- In STMFC@..., Jim Pickett <jimpick2001@...> wrote:

Never heard of a dentist using a belt sander inside a patient's mouth.


Jim Pickett

--- On Fri, 8/20/10, soolinehistory <destorzek@...> wrote:


From: soolinehistory <destorzek@...>
Subject: [STMFC] Re: Train of Thought- Sanding resin flash, or: avoiding bloody finger tips.
To: STMFC@...
Date: Friday, August 20, 2010, 8:43 AM


 





--- In STMFC@..., "Al and Patricia Westerfield" <westerfield@> wrote:

Denny - We once got a request for new stock car sides from a dentist who used a belt sander to remove the flash (and everything else. - Al Westerfield

Imagine what he'd do inside your mouth!

:-(

Dennis











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


tbarney2004
 

Pierre wrote:
At the risk of being put in jail;
Dentists prefer rotational action, thus a router would be more in order
Pierre Oliver

--- In STMFC@..., Jim Pickett <jimpick2001@...> wrote:

Never heard of a dentist using a belt sander inside a patient's mouth.


Jim Pickett

--- On Fri, 8/20/10, soolinehistory <destorzek@...> wrote:


I'd hate to find out of his dental drill does double duty drilling holes for grab irons. Those things would probably melt brass!

Tim Barney