Hi Everyone,
I'm working on a large train table that currently has 3" railings made from 5/4" boards attached on their edges to the table.  I attached the railings by driving wood screws through the bottom of the table and into the edges of the railing boards.   The corners of the railings were attached using wood screws.

I've decided I need higher railings for the layout I'm planning to make.  I don't have the bucks to buy a whole new set of wider 5/4" boards, so I bought some narrower (cheaper) 5/4" boards to add to the tops of the existing railings.

In other words, I want to stack 5/4" boards on their edges.  I figured I could use splicing cleats of some kind. 

I have some of those flat steel splicing plates used in construction.  I can use those to attach the stacked boards to each other from the insides of the railings.  It's pretty thin stuff, a lot more unobtrusive than wooden cleats would be.  I'll be using pan head wood screws to attach the plates. 

But now I'm wondering: is this really the best way to attach boards stacked on their edges to each other?  Would it actually be better to drive wood screws all the way through the edges of the top board into the side of the bottom board?  5/4" board is thicker than 3/4" lumber, but not by much.  As usual the dimensions are all really smaller than nominal because the lumber has been planed - so 5/4" board is slightly less than 1/2" thicker than 3/4" board.

Or is there some other, better way to attach boards stacked on their edges?

Thanks for your time,

Quote from: Jim Banner on January 16, 2010, 02:05:02 AM
Most likely, the solvent from your clear coat penetrated the primer.

Hi Jim,
I have an update that corroborates your observation once and for all.

I tried the Krylon Clear "Flat" Indoor/Outdoor spray.  It worked fine!  I got a nice, even, flat, protective coat on Krylon Flat Primer.

Evidently it was something in the Clear "Satin" that was causing the problem.  I haven't tried Clear Gloss yet as I have no use for it at this time, but I'll be sure to practice with caution when I do.

Once again my status as a cut 'n' paste amateur keeps me from knowing the reasons for this property of Krylon Clear paints.  If I were working with Minwax Satin vs. Minwax Flat polyurethane in cans, I would say that the leavening agents in the satin caused the problem with blotchy coats on the primer.  However I don't know what ingredient makes Krylon Clear "Satin" as opposed to "Flat".

But whatever the difference is, it makes Krylon Clear "Satin" useless on Krylon Flat Primer: it sets up in large blotchy patches with rainbow-hued edges.  "Flat" gives such a nice even coat that even a nervous ex-drinker like myself can spray a smooth surface.

I now have a sheet of high-impact polyurethane, 0.03" thick, 18" X 18", with a nice gray surface covered in protective clear-coat.  The color is a very close match to the gray used in the roadway pieces in the new Bridge and Turnpike sets. 

I FINALLY got something to work with spray paints!  It cost a lot of money and a vague sick feeling for a day after I painted, probably because of fumes in the basement, but I got it done!

By the way, my success with this particular combination of material and paint is probably not a predictor of anything anyone else might do with the same stuff. 

Oh yeah, one more thing: the paint is very flexible when set up.  I can bow this sheet of plastic in and out from all sides and corners with no obvious signs of crazing, rippling, or wrinkling of the dry paint.

So there it is.  On to the next disaster, which will involve attempts to paint and/or decal landing patterns and walkways for a heliport surface.  I've read in this forum that gloss surfaces work best with decals.  I'm hoping to make it work with flat surfaces.

Humbly, and yet humiliatedly,
Big Al Mintaka

Quote from: Jim Banner on January 16, 2010, 02:05:02 AM
Most likely, the solvent from your clear coat penetrated the primer.  Primer is to help bond the finish coat to the base material.  It is not intended to seal the surface against all and sundry.
...

I think I get the drift here.  Primer is a bonding agent for the finish coat, but doesn't necessarily protect the material from the finish coat paint.  In this case the Krylon clear satin was the finish coat, and it looked as though it had penetrated the primer and damaged the plastic - but see UPDATE below.

What bothers me about this is that both paints are Krylon indoor/outdoor, not the "Fusion for Plastic".  If the primer didn't hurt the plastic, why should the clear coat? 

However, there is an

UPDATE: now that the stuff has set overnight, the opacity of the primer coat has magically returned and it is now once again a solid color everywhere on the sheet.

Unfortunately the clear coat does look as though it dried in blotches in some areas.   To me it looked like the clear coat simply didn't cover those areas, so I added another coat just now.   I also added another support shim under the plastic sheet to make sure it was as flat as possible.

This coat filled in the previous blotches somewhat, but added more blotches of its own.  I think I know what's going on here.  Unless the material being painted is perfectly flat and level, Krylon clear coat flows away from the "high" areas and into the low areas.  This would be why the pattern of blotches looks different after I added the extra shim. 

Also, last night I painted some of my practice pieces with the Krylon clear to see what would happen.  These plastic squares were cut from the same high-impact polystyrene material.  They had been sprayed with a variety of paints - Krylon indoor/outdoor assorted colors, Krylon Fusion assorted colors, and 2 colors of Rustoleum.

One day later and I see that the Krylon clear coat has acted like paint remover on the Rustoleum "2x cover" Green.  However the Rustoleum flat black paint was undamaged.

And the blotches are showing up on some of these pieces too.  One of them was painted with the Krylon primer - no surprise there.  The flat black rustoleum shows blotches too.  But the Krylon Fusion Green doesn't.  There is a Krylon Fusion beige that might have blotches but it's hard to tell because the color is so light.

I'll be scanning and posting these as soon as they've set another day.  So far I can conclude the following:

Krylon primer doesn't bond Krylon Clear Satin.  The clear coat flows over the surface away from "high" areas and into low areas. 

Krylon Clear Satin does coat smoothy on Krylon Fusion For Plasic paint, but not Krylon indoor/outdoor paint.  It blotches on the latter too, flowing into low areas and leaving high areas uncoated.

This doesn't speak well for Krylon primer.  Since it is indoor/outdoor primer, it should bond indoor/outdoor paint.  It doesn't.  It does bond Krylon Fusion for Plastic.

As said, I'll try to post scans of the practice pieces tomorrow. You'll be able to see what I mean by these blotchy areas.  BTW the edges of those blotchy areas give off a rainbow hue of reflected light. 

Quote from: Jim Banner on January 16, 2010, 02:05:02 AM
...
I assume you are buying your Krylon in consumer spray cans, not commercial drums, and that you are applying it with the spray cans, not an air brush or paint sprayer.  In this case, you might want to be careful where you buy your paints. 
...

Yes, that's me.  I'm strictly a cut 'n' paste amateur.   I don't have fancy airbrush tools, compressors, or even a small spraying booth.  I spray in an unfinished basement.  I save my spraying jobs up until I have a good number of them.  I'm careful when I spray, at the right distance depending on the paint and results on practice pieces, in smooth motions, no starts and stops except between pieces when I'm "mixing" the rattle cans.  I move from one end of the assembled jobs to the other and then get out of the basement fast.  In warmer weather I spend more time down there because I can ventilate with fans.  Right now that's not an option.

I get the Krylon from Walmart or wherever else it's on sale.  I don't bother asking the assistants there about which is better for what task.  I do that online in forums, where I've been reading that Krylon arcylic lacquers (and the sythetic lacquers in spray cans) are safer for use on foam core than harda*** enamels like Rustoleum, which also dissolves skin and mucous membranes. 

The guys who know things work at Hobby Town in Nashua and are the only ones I've found so far who can talk about these paints.  Unfortunately they're very pricey.  The Tamiya Arylic jars are small for what I want to do with these large surfaces and would run up a pretty large expense tab.  They have a very limited supply of the spray synthetic lacquers too, in small cans and also high priced. 

I have some of the Tamiya in jars for small pieces.  I've been resisting using the sprays only because of cost, but now it looks as though the only way I can do what I want to do with plastic is to pay the big bucks.  I'm open to suggestion about how to buy larger quantities of Tamiya without breaking the bank.

You may be able to tell from my tone here that I'm a little discouraged for lack of progress, even with these practice pieces.  I have one of those HG Wells Martian War Machines here and I don't dare go anywhere near that until I figure out how to do this without wrecking the thing. 

One thing I've already decided about that War Machine though - I don't think I'll be using the Gold Leaf sheets like some of the hardcore modelers here and on the HobbyTalk forum!

More updates and scans to follow,
Big Al Mintaka

Hi Everyone,
Now that I seem to have found the right materials for the different structure elements I need, I've moved immediately on to a painting disaster.

I've been practicing with Krylon spray paints on high-impact polystyrene sheets.  The sheets are 18" X 24", .030" thick, opaque white.  If you've ever worked with Kenner's old Girder & Panel/Bridge and Turnpike sets, it's the same material used in the wall panels and roadways - only a little thicker.

Gray Krylon Primer went on very well, gave a nice smooth even coat, and didn't attack the plastic.  So far, so good.

I liked the color the way it was and decided to use the primer as is for the coloring.  However I found out through experimentation with this primer on other materials that it marks easily after it's dry.  So I decided to try one of the Krylon clear coats.  I waited a few days until the primer coat had cured (at least I thought it had).

Then I practiced a bit with Krylon clear satin on scrap pieces of styrene and wood.  Once I had the hang of laying on those materials, I started spraying the primed polystyrene sheet.

It came out horrible!  The nice uniform gray color of the primer is now splotchy.  The splotches didn't change after they first appeared.   Even though I continued until I had sprayed on an even coat they stayed the same.  What the...

I looked at the material from different angles to make sure I had an even coat of the clear.  The surface looked wet, smooth continuous, no dry spots.  I waited but there was no change in the splotches.  However I noticed after a while that I was starting to see the support shims underneath the sheet right through the plastic!  It's now semi-transluscent in some areas, splotchy in others, and solid gray in the remaining areas. 

What could this be?  The primer certainly didn't have any damaging effects on the plastic, but now the Krylon Clear Satin seems to have turned this thing into a wet oil painting on slowly melting plexiglass. 

Could this be

a. The primer not being really cured?  The clear coat could have semi-dissolved areas that weren't as cured as others, though why it would cure that way I can't figure.  Even if it weren't completely cured though, I still shouldn't be able to see through the sheet as the unpainted material was opaque white.

b. The clear coat does something to the polystyrene that the primer doesn't?   That makes no sense to me, but then neither does a blotchy clear coat that eats through primer and makes solid white polystyrene semi-transluscent.

c.  Something else, whatever that might be.  I have 4 kinds of Krylon paint here: the can of gray primer, 3 cans of "indoor/outdoor" colors, 3 cans of "Fusion for plastic" colors, and 3 cans of clear coat: flat, satin, and gloss.  Clear satin was the one I used on the primed polystyrene.  The other types of spray colors don't even figure into this.  Yet.

Has anyone else seen Krylon sprays do this to plastic before?

Thanks for your time,
Big Al Mintaka

Quote from: CNE Runner on January 13, 2010, 10:17:31 AM
...
Out of the available products I have purchased the cutting guide, straight cutter, V-groove cutter, and rabbet cutter. In addition to my purchases the company offers a bevel cutter, a freestyle cutter, a large hole cutter, and several sizes of small hole cutters. WARNING: these cutters are expensive! I used the 40% off coupon to bring their prices more in line with my budget.
...

Hi Ray,
You're right, those things are pricey.  Where'd you get that coupon?  I have an Amazon $25.00 gift certificate that would buy only one of the cheaper cutters, going by Amazon prices that is.  The local retailers listed on the Foamwerks page don't list the cutters in their online stores, which probably means they'd have to order them. 

At the local hobby shop they sell the Woodland Scenics hot-wire cutter with a bow guide accessory that makes it look like a coping saw.  As usual with anything made by Woodland Scenics, it's priced high, almost 50 bucks for the cutter and bow. 

At these prices for the Foamwerks and Woodland Scenics cutters, looks like I'll be roughing it for a while with whatever I have on hand.

For foam I've been using a utility knife for straight cuts.  It works OK as long as the blade is sharp.  Otherwise it catches and drags crud along, ruining the cut.  The hassle with even a sharp blade is trying not to get a bevel cut on a thick piece of foam.

That high-impact styrene, on the other hand, cuts very easily with a pair of paper scissors.  I draw a square line, then very carefully cut along it with the scissors.  This works better than a utility blade or hobby knife.  Either of those take several passes to get through even 0.03" of the stuff.  It's hard to hold the line on succeeding cuts, resulting in an uneven edge. 

For legal size sheets or smaller, I use an old-fashioned office paper cutter.

If I have the shed business right, this is an outlying structure you're going to build for your train setup?  Have you looked into the prefabs, wood or metal?

"Progress marches on".

Have a good one,
Big Al Mintaka

Hey All,
If anyone's still keeping an eye on this thread, I've been getting continuously better results as I experiment with different roofing materials. 

Masonite is still great for bases and walls but it weighs a little too much for the large flat roofs and decks I want to build. 

I used art shop foam board (foam core between two sheets of acid-free cardstock).  It can take any kind of spray paint I've been throwing at it: Rustoleum, Krylon, Krylon Fusion (supposedly special for plastics).    Enamel like Rustoleum that would normally eat right through foam core that wasn't protected somehow, gives a nice coat of paint on the cardstock without leaking through to erode the foam inside.  There is some very minor scoring of the foam at the edges between the cardstock sheets but nothing really serious if the roof is going to have some sort of edging.  The drawback with this stuff is cost.  It's big bucks.

Also I finally found an outfit that sells high-impact styrene sheets in sizes I can use.  It turns out that styrene sheeting 0.03" thick is pretty much the same material used in these Girder and Panel/Bridge and Turnpike sets for wall/roof panels and roadways.  This styrene is perfect for flat roofs, interior floors, and decking.  Also I can cut holes at the edges for the anchoring beams using a hand-held paper cutter.  The right size for making ring binder holes works fine.  I haven't had to cut any holes away from the edges yet but I'm not worried about that. 

This stuff takes Rustoleum and Krylon with no trouble.  If the Rustoleum is compromising the styrene somehow I sure can't see it. 

Here's the place that sells the plastic sheets in affordable lots of flat stock and larger amounts on rolls.  I bought 25 sheets of the High Impact Polystyrene 0.03" 18" X 24" flat stock/white.  There's no clear; the other color available is black.  I chose white because I figured it would be easier to paint.

http://www.professionalplastics.com

Now I'm sure those of you who've done a lot of work with plastic sheeting have better ideas about the material.  I chose this particular stuff based on a combo of cost and similarity to the material used in the Kenner sets.  These guys sell all kinds of other plastics in sheets, rolls, and rods.  I have no idea of tradeoffs between the types yet, for example why this high-impact styrene is any better than polypropylene for what I'm doing.

Krylon gray primer on this styrene sheeting is the perfect color and material for what I want.  The only problem is that the primer is easily marked in handling and so will require some kind of clear-coating or sealing.  Or, gray Krylon Fusion finish paint that's about the same color.

Anyway that's where the flat roof (and now flooring and decking) effort is at.  I have a long and expensive learning curve.  Here's hoping I'm finally converging on a solution.

Have a good one,
Big Al Mintaka

Hi Everyone,
Thanks for the great responses.  I can see by your questions where I didn't supply enough information, so here goes:

Project: 18" X 18" HO scale heliport deck.  No cutouts, a slight amount of custom trimming along the edges to fit the building frame.  Landing patterns and other markings will be added later using wet decals (I print my own on a color laserjet, no smearing).

The materials I've tried so far are:

• Fan-fold foam insulation sheets (Lowe's), laminated on one side with a very thin vapor barrier of clear plastic.  Too much surface rippling and other imperfections to be useful, spray enamel attacks it, spray acrylic can't be spread evenly (even the primer)
• Masonite, takes all kinds of paint, smooth surface great for the heliport, but the 18" X 18" sheet is too heavy for the structure.
• Foam core as described by CNE Runner: foam sandwiched between some kind of paper/carboard laminate.  In this case I got acid-free foam core at an art supply store where they use it for frame backing, so it costs big bucks to use it.  The surface can take spray acrylic or enamel.  Enamel that lands on the edges causes slight scoring but not enough to worry about.  As of tonight, spray enamel spreads much more evenly on this stuff than acrylic.   I may have solved my problem with spray acrylics right here via just not using them for this project.

I have yet to try brushing jarred arcylics on this material.  I will definitely experiment with that as I have enough practice pieces.  But if this type of foam core is what I'll be using in the future , I need to find a cheaper way to get  hold of it.

None of this solves my problems working with spray acrylics.  I'm far from being an expert at spray painting but with patience I can get decent coverage with the enamels.  The acrylics just won't spread evenly for some reason.  Maybe the option of using thinner with the jarred acrylics is what's missing here.

So I'm now shopping around for cheaper foam core.  I'm still too PO to talk about the glues, especially Gorilla CA and expoxy.

Anyway thanks once again for these replies, especially the photos in CNE Runner's response.

Have a good one,
Big Al Mintaka 

Hi Everyone,
I'm just getting into gluing and painting some of the structures I've been working on and have run into a dead end.  I won't go into my experiences with the so-called cyano "super glues" because that would take a book, and one of these topics at a time is more than enough.  Suffice it to say that the super glues are now in the trash and good riddance to them.

Spray paint problems: I'm working with foam core at the moment.  I found out the hard way that enamels do a number on this stuff, so after asking around I got some Tamiya spray acrylics and started practicing with that.

I started with flat gray primer.  I noticed some problems trying to get an even coat as this spray didn't spread around the same way the enamels did.  I practiced on test pieces for some time then applied the spray to the foam.  I was very careful but still could not get an even coat.  Since it was primer, I figured it wasn't so important.

It set up quickly but I waited a day to apply a top coat.  I selected "Gun Metal Gray" spray acrylic, Tamiya again, and began practicing. 

It was disaster.  No matter how hard I tried and how carefully I applied the paint, the result was grotesque rippling on primed foam.  Unprimed foam behaved the same way.  What could I be doing wrong here?  No matter what I do, it seems impossible to get an even coat of this stuff.  Even the areas where I applied a very light coat began to ripple as soon as I stopped spraying. 

Temperature wise I think I'm OK.  It's in the mid 60's F in the basement.  Following up on some other advice, I tried warming the paint can in mildly warm tap water.  I still got the ripples.

All the practice pieces are ruined.  The paint is rippled everywhere.  I figured the only thing I would dare do at this point is to forget the gun metal gray paint and put another coat of the gray primer on the finish piece.  There was no rippling on the piece from the first coat of primer, but sure enough the coat turned out to be uneven.  It was easy to see that much with the paint dried.

I practiced with the primer again on a few more throwaway pieces of foam until I was certain I had the hang of getting the primer on in an even coat.  Then I carefully painted the finish piece the same way.

I just went downstairs to check on the work.  Once again, the primer coat is uneven on all the pieces, practice and finish.

I'm at a loss.  I can't understand what I could be doing wrong here with these paints.  I know this stuff takes practice.  On the other hand all I'm trying to do is get a uniform coat of some kind of paint on foam core.  Enamel destroys the material and these acrylics either coat unevenly no matter how they're applied, or develop gross rippling patterns.

I should add that those "ripples" are in the paint, not the material.  Also, they don't seem to be lines of really think gobs of paint with thin paint in between.  There's no sign of running, drops, etc.  Viewed up close and/or touched with a finger, the coat is thin.  It seems like only the color that's rippling like that.

Does anyone have any ideas on this?  Sorry to make this so long.  I didn't know how else to report these problems without going into some detail about how I applied this paint.

Hope everyone's holidays are going well,
Big Al Mintaka

Quote from: CNE Runner on December 24, 2009, 11:58:03 AM
Al - If I may repeat myself: Foamcore makes a much better building material than Masonite (hardboard). Hobby Lobby carries nice large sheets of foamcore (20"x 30"); and sells them for $1.99 each. You can easily build a medium sized (in HO) structure with one sheet. The only drawback is that Hobby Lobby only carries this product in white (it can be had elsewhere in a variety of colors). If you require larger sheets, you local sign shop can get it in 4'x 8' panels...possibly larger).

In summary, foamcore is cheap and easy to work with. You have already 'experimented' with hardboard...why continue down a path laced with diminishing returns? The only application I have found foamcore lacking is as transfer table material. The foamcore is much too light...5 mm birch plywood is much better (with the addition of automobile wheel weights...even better).

Get a piece of foamcore - a low temperature hot glue gun - and experiment. With the application of printed paper transfers, and weathering, you will be pleasantly surprised.

Ray

Hi Ray,
As I noted,

"So now I'm experimenting with various kinds of foam to serve as a lightweight roof.  I bought some fan-fold foam 3/8" thick and practiced my nonexistent cutting skills until I got the right shape without beveled edges."

The fan-fold foam I bought is the same material as foamcore.  Sorry, I should have been more explicit about what that stuff is.  That's what I'm experimenting with when using the acrylics.

The local hobby shop sells foamcore in sheets that are too small, and wants ridiculously high prices for larger sheets.  Thus I appreciate your reference to the Hobby Lobby.  If they have a website, I'll find it.

White doesn't bother me so much.  I can prime and paint whatever colors I need to get the job done.  The only limiting factor has been cost around here, except for that fan-fold stuff. 

The problem with the fan-fold foam, as I'm now finding out, is that there are a lot of surface imperfections that need to be treated before painting.  They weren't really obvious until after the first coat of acrylic primer last night.  There are numerous pinholes (prob from handling equipment) and a very slight rippling that is easily seen with the primer.  I've spackled a second sheet and will be sanding that to see if I can get a flat surface.

But it's a lot of work just for a flat surface.  I will look into that foamcore at Hobby Lobby, thanks again for the reference.

Just a note here: I wouldn't be too hasty with calling Masonite a "dimishing returns" venture.  It's still great for flat surfaces with no cutouts, and excellent as roadbeds on raised track, highways, and bridges.  For printed transfers it's every bit as good as any other flat material that can be glued.  The two surfaces it already has - gloss and matte - are already prepped to go for whatever applications require those finishes.  The matte side is particularly good for flat tar roofing and rural roadbeds.

In addition, as I pointed out in my very first post, I have a ton of this stuff and it's all free.  It's far from being "diminishing returns" in all those respects.  If anything, what I've learned so far only limits it in those two categeries I happen to need for my application: small cutouts and weight (for large roof spans).

That's about the listing of end results so far.  What I still don't know is whether the acrylic paint I've been having to use with these foam products is dangerous - especially the sprays, which are really synthetic lacquers and stink to high bull orifice, much more than enamel sprays.  I have a big unfinished basement I can evacuate after I'm done working until the vapors settle but no praying booth, and this time of year no decent ventilation.

Sorry to ramble.  To echo Woody, Merry Christmas, Happy New Year, Happy Chanukah, Happy Kwanzaa, Lecherous Saturnalia (that one's mine), and Joyous Etc too all!

Big Al Mintaka

Hi Everyone,
I've been playing with Masonite and a few other materials and thought I'd post a followup.  Masonite is working very well for flat surfaces, not so well for cutouts as some of the posters predicted.  It's great for roofs of all kinds.

Right away I ran into a problem with the weight of Masonite.  I have a large structure with a square heliport on the roof.  It's 18" on each side.  To save on building materials (Kenner's Girder & Panel) I made the tower underneath the heliport narrower than the top.  The total height is 41".  For the materials typically used in Girder & Panel buildings, it's a very solid structure.

However when I plopped the 18" sq Masonite roof on top, the weight of the roof made the structure unstable - as in wicked top-heavy.

So now I'm experimenting with various kinds of foam to serve as a lightweight roof.  I bought some fan-fold foam 3/8" thick and practiced my nonexistent cutting skills until I got the right shape without beveled edges.

I learned the stupid way that spray enamel isn't kind to foam.  I knew beforehand that gasoline dissolves styrofoam but didn't make the connection with some of the solvents in spray enamel.

So I cut another roof and am now painting with spray acrylic - the Tamiya stuff.  The first coat of primer didn't dissolve the roof, so it's a go so far.

But this raised another question with regard to structural materials, finishing methods, painting, etc.  As I was spraying the acrylic on the roof, I started to get the distinct impression that this stuff is really, really bad for you.  Is that the case?  It's a lot more foul smelling than enamel, that's for sure. 

Assuming I survive, I have decal paper for my color laserjet and will experiment with decals for landing patterns on the roof.  That's a ways down the road.

One other foam I may try soon is foam backing board used in framing prints.  I have a few squares of it and it's really nice stuff.  It's also extremely expensive.  I'm resisting using it unless the fan-fold stuff turns out to be just unworkable.

The long way around is done and the question that appeared was: is acrylic bad stuff healthwise?  The writing on the can is all in Japanese chars so I can't tell what the warnings are, if any. 

Thanks to all for taking the time to read this and have a good one,

Big Al Mintaka

Hi Everyone,
I've been looking into LED lighting for my HO layout.  I make use of a lot of structures made from the old Kenner's Girder and Panel building sets; cool lighting is essential because of the plastic material used in the panels.

I'm not too knowledgeable when it comes to LED circuit design, so I decided to get some sets of LED Christmas lights and take them apart to see how they worked.  I started with sets of 20 LED lights ("C3") powered by 3 1.5V AA batteries.   The manufacturer rates the LED bulbs as 4.5V 90mW. 

The 3 AA batteries are connected in series, so the total voltage is 4.5V.  A 4.7 Ohm resistor is wired to the + terminal of the batteries (resistor color code = yellow violet gold gold).  The 20 LEDs are connected in parallel to the other side of the resistor and the - terminal of the batteries.

My confusion has to do with how I might expand this circuit to include more bulbs, and how I might replace the batteries with a DC power supply. 

I ran the numbers through some of the online LED current limiting resistor calculators, e.g. the "series parallel array wizard" at http://led.linear1.org/led.wiz. 

I started by assuming that the forward current for each LED was 20mA.  This seemed like a typical value in the various places I looked online. 

Then I experimented with different values for the LED forward voltage until the current limiting resistor for my circuit corresponded to the 4.7 Ohm resistor I found in the Christmas set.  The forward voltage required to make this happen was 4.42V.

Isn't that a little on the high side for LEDs?  The values I've found online are closer to 3.0V on average for the different colors.  I tried this with a few other calculators and kept coming up with the same value for forward voltage.

So the first question is, am I doing this the right way?  For a circuit of 20 LEDs connected in parallel to a 4.5V supply with a current limiting resistor of 4.7 Ohms and LED forward current of 20mA, does a forward voltage of 4.42V make sense?

Secondly, if I replaced the batteries with some kind of DC power supply, could I use something like one of those "wall wart" DC transformers rated for 4.5V 20mA?  Would I still need the current limiting 4.7 Ohm resistor if the transformer is rated for 20mA? 

Finally, how many LEDs could I really add in parallel to this circuit?  Using the above mentioned array calculator, I added another 20 LEDs, then 40, then 80, and the solution was always the same: 4.5V supply, 4.7 Ohm current limiting resistor, LED forward current 20mA and forward voltage 4.42V.   There must be a practical limit to the number if LEDs I could add before something has to change, but what is it?

I'm missing something here but I'm too stupid to understand what it is.  I just want to find out how to calculate the right component and power supply values if I start adding LEDs to this circuit. 

Thanks for your time reading this convoluted message,
Big Al Mintaka

Thanks to all for the useful advice! 

jerryl's point about cutouts is well taken.  The table and miter saws I have (courtesy my Dad, a real Renaissance jack of all trades) are great for cutting shapes with masonite, but cutouts are another matter.  I have to use a utility or hobby knife/saw for that sort of work, and it's tough to get square, straight edges (and keep from severing arteries at the same time).

Already I can see that the masonite is going to make a good underlying structure but that some kind of outer layerings are going to be needed both for realistic looks and to cover the numerous cutout gaffes.

I'm still fooling around with that idea of layering toilet paper, paper tape, etc for shingle effects.  The paper tape used for bandages sets up very well after being painted over but has serrated, uneven edges.  Cutting the stuff lengthwise to true it up and make straight edges would be a real chore.  Too bad, because it makes a great roof peak cap/hinge.

There are two other experiments waiting to set up.  One uses regular masking tape for the peak cap, the other uses freezer tape.  So far the freezer tape looks like the better bet because it absorbs the paint, which will help it adhere to the masonite better.  Also the adhesive on freezer tape is pretty robust stuff, formulated as it is for temperature extremes.  The masking tape looks great painted but I have doubts about how well it will stay stuck to the masonite.

Printed overlays with glue stick or other adhesion is a great idea too.  I have a color laserjet here that I can use to create ad-hoc patterns of any kind, with fused toner that won't behave badly if any moisture is involved in the gluing/painting process.  This printer, a LexMark C510, is also good with a wide range of paper types so I can experiment with different materials to see what works best when glued on masonite.  "Clever Models" - I'll make a note of that, thanks Ray and mabloodhound (latter for the link).

With all this experimenting going on, it's getting hard to see the proverbial forest through the trees.  As a possibly unrelated side note, I also collect old building sets - American Plastic Bricks, Lincoln Logs (redwood trestles coming up!), Girder and Panel, etc.  This masonite is turning out to be a great roofing and flooring material for those applications as well.  In particular, the cardstock roofs that came with the old plastic bricks sets hasn't held up well over time, and painted/textured masonite is the perfect substitute.

The old Girder and Panel/Bridge and Turnpike truss bridges with masonite beds look fantastic.  Those Kenner sets are HO scale too, real 1:87.  Bridge Street Toys (http://www.bridgestreettoys.com/index.html) is selling recast sets/parts now.

And now I've found that for flat roofs, painted masonite squares with the textured sides up are perfect.  Never mind that some of those pits are almost a foot deep in HO scale - it looks great.

Progress marches on.  I'm not even done with the table yet.  I expect that I'll soon be posting questions about inverted cone LED lighting for those Girder and Panel structures which I will be using in the layout. 

I'll keep you all posted on developments with the masonite!

Thanks once again to all for the helpful advice,
Big Al Mintaka

"I believe a leaf of grass
is no less than the journey-work of the stars."
--Walt Whitman

Hi Everyone,
I've wound up with a ton of 1/8" scrap masonite and was wondering if it could be used to make structures for my HO layout.  When I search the internet for advice on this topic, I find that most model railroaders use masonite for roadbeds or large backdrops, but no one seems to use it for structures.

Is this a bad idea?  Given the fact that I already have this stuff, I don't have worry about cost issues, only whether or not making buildings out of it is worthwhile.  Some of the concerns voiced on the sites I found had to do with humidity and how it can make masonite warp.  But for small HO structures, it doesn't seem as though warping could be much of a problem - the pieces will all be small and everything will be tacked (with brads) or glued tight to interior wood bracing. 

I've experimented with various kinds of spray paint I have around here.  The masonite holds up with Rustoleum and model enamel, no sign of warping that is, and the "shiny" side takes the paint very well.

I've even been able to cobble up a nice looking peaked roof with it.  I start with a rectangular piece of masonite a little longer than the house and a little wider than twice each half of the roof (for overhang).  Then, using my table saw, I cut a narrow groove (one pass with the blade) the length of the roof, underneath where the peak will be.  This takes a little practice because the groove has to be just the right depth.  Too deep saws the roof in half, argh, and too shallow makes the peak fold look ragged.

Anyway, once the groove is cut, the masonite is carefully folded - not in half, just to the angle of the roof's peak.  The seam on the outside doesn't look bad at all provided the groove was not cut too shallow.  Then I place the roof on two wooden protoype peaks and spray paint it in the folded position. 

This makes the paint look uniform across the peak, but it also looks unnatural to have a perfectly straight-edged peak like that.  So, taking a cue from the folks who simulate shingled finishes using overlapping strips of painted tissue paper, I'm experimenting with a single strip of paper tape along the peak, painted over after it's glued in place.  It hasn't set up yet but with any luck it'll look at least something like a row of peak ridge material of some kind. 

Well, obviously I'm still in the experimental stages of using masonite this way.  Has anyone else used it to make structures, and if so, how have they held up over time?

Thanks to all for taking the time to read this,
Big Al Mintaka

"I believe a leaf of grass
is no less than the journey-work of the stars."
--Walt Whitman

Hi Everyone,
I have two of those vintage De Witt Clinton sets.  One of them runs fine, starting up smoothly and running nice and steadily.

The other one is a little slow out of the gate and sometimes jerks a bit until it gets going.  Once it's rolling, it moves a lot slower than the other De Witt. 

The motors in these things are pretty small so I imagine they have their work cut out for them even when running up to speed.  But is it typical for two motors to perform so differently?

The startup is what bothers me most.  A few times I've had to give it a nudge to get it going.  At least it keeps going once it starts.

I haven't tried to do anything maintenance-wise with it yet.  Has anyone else run into this sort of thing before, and are there some rule-of-thumb techniques (i.e. lubing or refitting the wheels or something) that might help in a case like this?

Unfortunately I was slow in getting these things onto a test track so I doubt they're still under the DOA part of the warranty.  If I can I'd like to try working this myself but don't want to touch it until I've heard from the experts.

These little vintage trains are really nice as far as workmanship goes.  I'll have to learn more about these and other vintage engines so I can hunt around for any other sets that might be lurking out there.  I really like these things!

Take care and thanks for reading this,
Big Al Mintaka

Hi Everyone,
I recently bought one of those Bachmann John Bull sets.  It's a great little train as far as workmanship goes and the motor runs reliably on my test track.  What I've noticed though is that it has a significant problem on curved track. 

It's a 2-4-0 with the front two wheels in a fixed frame.  That fixed frame is where the problem lies.  On track that's curved, the front two wheels are easily derailed.

It can't handle 18" radius at all.  I know this is pushing it for HO locomotives, but I haven't had any problems with that radius using 4-4-0 locomotives or other trains in the "Vintage" series such as the Dewitt Clinton or Lafayette.

For 22" to 28" radius, the front wheels will derail if the train is moving faster than a slow crawl.  I don't have tracks of larger radius on hand at the moment, but I doubt I'm going to want to go much higher than 28" with my current layout.

I was wondering if anyone else who happened to have this train was experiencing similar problems and/or if anyone had any suggestions about what I might do to try to fix this. 

If the front wheels could turn even a small amount , this wouldn't be an issue at all.  I'm wondering if I can do some kind of mod to make the thing work.  Unfortunately those little wheels are pretty restricted in that frame.  There's not a lot of room to move things around.

Anyway, thanks to all who take the time to read this and have a good day!

Big Al Mintaka