Kato Mikado weight info and ideas

[Mark W]

Has anyone actually measured the volume of the original weight?  We could talk density all day, but it still comes down to how much volume there is to work with. Is it really worth all the extra trouble to cast a weight when the only gain is a few tenths of a gram vs just squishing tungsten putty in?  Or why not squish the putty in and around the lead/tungsten rods?  You're done in 3 minutes and have virtually the same result as if you had cast the weight. 

Based on quick googling, Tungsten putty comes in around 9-10g/cm3  Lead is 11.something.  There's maybe 1.5cm3 of free volume in the Mike?  How much improvement can 4.5 grams really do here for all the work it would take to achieve it?  That's the weight of 2 pennies, which also happens to be the value of this comment.

[Chris333]

In the first post Max said he pulled the stock 10g weight and put in sheet lead that was 20g. So he instantly doubled that weight without trying. He's looking for a way to get even more.

[mmagliaro]

In the first post Max said he pulled the stock 10g weight and put in sheet lead that was 20g. So he instantly doubled that weight without trying. He's looking for a way to get even more.

Chris, thanks for reading, (and remembering!)   

Yes, just by stacking up some thin tungsten and lead plates to the approximate side of the original weight, I about doubled the weight.
So now, I've made a mold of the weight in cement (it's hardening as we speak), so I can pour it with liquified lead
(just drop some into the cement cavity and hit it with a torch).   That will be pure lead.
Then I'll try it with a thin bit of lead and a row of tungsten blocks, then more lead, all melted so I get a perfectly formed weight
that fills the cavity with lead, but has tungsten embedded in it.

It all may not be worth it, but then again, if it adds appreciable weight and traction by just casting a simple lead weight and dropping
it in to the engine, that would be a lot easier than stuffing the body everywhere, which I've done on plenty of engines.
This is about experiments to find an easier way.

[peteski]

Cement mold?!  Sounds like a bit of an overkill.  Long time ago I made lead molds from Plaster of Paris. They worked well, but you have to make sure that they are thoroughly dry.  It takes a long time for all the water to evaporate.  If there is moisture in the plaster, it will boil under the lead creating voids.

But nowadays, many silicone RTV rubbers can easily withstand the temperatures of molten lead.  That is easier and quicker than using plaster.

EDIT:
Just adding that I do like the idea of using solid lead (not putty) to fill the voids in the tungsten material. It is like having best of both worlds.

[Mark W]

Yes, I read and agree lead/tungsten bar-stock are a worth while upgrade from the original weight.  My question is; is casting lead or a lead/tungsten hybrid weight worth the time/effort investment vs using tungsten putty as the filling agent?

Instead of tungsten bar-stock cast in lead filler, the same amount of tungsten bar-stock squished into tungsten putty filler.

I would be interested in seeing how this method would compare to your castings.  Both in end-weight result, cost, and time to create.  *edit* and if the difference in weight (if it only turns out to be a few grams) actually affects pulling ability.

[Lemosteam]

Frankly I've never understood, except in the case of a custom built bolier shell like Chris333 does, why one would not simply want to copy the weight that was specifically designed to fit within a manufacturers shell?  Fitting and piecing tungsten will only leave air gaps so you will never see the full benefit.  The filler in tunsten putty merely does the same thing as air, so you don't get the full cavity filling effects of the lead.

Max, I got eight castings out of the mold in my video before the mold started to deteriorate.

When I used the play clay, it worked pefectly for a one-off.  The inner surface would bake and i would just throw that bit away and make a new mold.  Poured it right in front of my computer on my desk.

I agree with peteski- make sure you wait a couple of days or maybe bake the concret mold before you use it.  I have been told that a hot mold accepts the molten metal better.  Did you use mortar mix?

[Chris333]

Max is simply following instructions, the box says Heavy Mikado. 

[mmagliaro]

Guys,
I made a mold of cement because I had some.  I just used straight cement, not mortar mix, because I thought it would make for a smoother mold.   A cement mold is going to be on the rough side as it is.
I don't know if I'd call it "overkill".  It was really easy to make.

I did do some reading and yes, people cast molten lead in silicone rubber molds, so I picked up a tube of high temperature silicone sealant (it's supposed to be fire resistant and good for up to 2000 degrees F).  I may try that next just to see if the mold is cleaner and smoother (I expect it will be).

As for "why do this", if it works, believe me, it will be a heck of a lot easier to pour liquid lead into a mold, kick it out, pour again, and so on, to make these.  Once they are made, they become "upgrade parts" for Mikados.

I have to admit that tungsten putty looks like a good choice for replacing lead, since it is as dense as lead, is easier to work with and can fill every void.

[Mark W]

Here ya go. 

[mmagliaro]

Here ya go.

Absolutely!  Gold.  As heavy as tungsten.  Soft, cuttable, solderable.   You get right on that and send me all the cheap surplus 24k gold you can find.

[Lemosteam]

There's not a lot of vertical wall draft on this particilar part, but still I am concerned that the lead may be difficult to extract from the mold as the concerte is porous and the lead may stick to it- you may want to try the paperclip trick- insert a paterclip into the lead before it solidifies.

That's what's nice about the clay- once it cools, you just peel it off the casting and make another.

On the JB weld mold, I had to make sure I had positive draft before I poured the first one.  Even then it was hard to get out of there sometimes.

I trued tube silocone once- tride to make a mold all at once- it NEVER solidified.  You may have to use layers until you build up enough over the parent part.  I am about to try a casting in a silicone mold for resin castings- it was rated over 600 deg.

As for the putty, how would you know that all voids have been filled since you cant see into the shell?

[peteski]

Max, I wasn't talking about silicone sealant.   I specifically mentioned RTV silicone rubber - the stuff used for making molds for urethane resin castings.  Like John says, caulking will not fully set in thick layers - it is not designed to. RTV rubber material will.  But if you like cement molds, go for it!

[robert3985]

While all is well and good with making a steam engine as heavy as is practically possible, with my Brass Key FEF's I got worried about how the power to the drivers was transmitted...which was one geared driver...the rest got theirs from the Nickel Silver rods.  Gotta remember, I weighted these to pull 60+ cars in an Ntrak environment...y'know...round and round and round and...you get the picture.  Even though I could have made these models heavier and they would have pulled mo' cars, 60 to 65 cars was plenty for me, and they are heavy enough that I always lubed up the rods at the beginning of a running session on the Ntrak layout when the club would set up. 

No perceptible ovalizing of the holes in the rods that I can measure, but...I'm sure there would have been if I hadn't used a quality lube every time I ran those FEF's.

Now, with these pulling only passenger cars at a maximum length of 9' 7.5" the heaviness of these engines seems like overkill.  I can always dip the boilers in boiling water to remove the Cerrobend if I want, so it's not a big deal.

However, with a LOT of extra weight, remember that lube actually becomes necessary...especially with long trains.

Just sayin'...

[mmagliaro]

In the case of the Mikado, 3 drivers are geared, and the forward driver just goes around for show,
carrying very little weight.  Plus, these are stainless steel rods and crankpins.  If those wear out,
I give up!

An RTV mold is probably a much better way to go for this, as it will make a much cleaner, more precise
weight than cement.
I should have listened closer about the dangers of the trapped water.  I thought the cement mold was dry,
but as soon as the hot lead hit it, I heard the sound of a boiling, escaping bit of water from beneath the mold,
and fragment burst right out of it.  So, no go on my first crude attempt.
However, I did have about a half-filled pour in there, and even that little bit weighs 10 grams!  So I have high
hopes that when I pour a full one, I can get up to 20, and that's *without* embedding any tungsten in it.

Trial one was a failure, but did provide me with a hint that this will probably produce
a very heavy weight if I stick with it.

Can RTV really withstand the temperature of molten lead?

[Lemosteam]

The product should specify a temp rating.  I know the one I used did.  I'll let you know how it goes.  I made a mold inside an m&m tube, and I am going to use it to keep the mold closed. I used wire to support the master, an when I pulled the wires out, I should have some air vents.  Fingers crossed. 

That was one nice thing about the JB weld+sand it is rated for 600+ degrees.  There was no moisture in the mold and the walls were smooth.

Peteski, I would imagine that a layered buildup of rtv would work, it just seems like it would take forever to make the mold.