Weekend Update 1/29/17

[arbomambo]

A little paint on the Greyhound terminal....more to go still.

Beautiful!
What kit is this?
~Bruce

[JoeD]

at first I thought it was the Imax model but this is bigger and better executed.  scratch built???   


Joe

[peteski]

Yep...HO.  I am working on this in N scale too, but it's really difficult given the size.  I took the trucks from our SW 1500 and made a mold and cast them in tinted resin so I have something I can get paint to stick to. I might have better success with that then the Engineering plastic.

Joe

Since you work at MTL, couldn't you (on a weekend maybe) just make a small run of those using styrene instead of Delrin?   Or it doesn't work that way?

[JoeD]

Since you work at MTL, couldn't you (on a weekend maybe) just make a small run of those using styrene instead of Delrin?   Or it doesn't work that way?

Great minds...   I tried this a few years ago with our trucks hoping I could launch a line of Styrene shots of our trucks and couplers for the detailer market.  We can get good shots of the outside detail but when the parts are ejected the bottom of the journals split open when they are pushed past the cone inserts.  Styrene is very stiff and splinters pretty easy when molded like this.   We already do them out of Celcon which is a brother of Delrin.  I tried ABS too but the pressure setting to get them to fill caused a lot of flash.  I think there is a market for "kits" of trucks molded like I did the HON3 trucks we produce.  These pivoted when going over rough track and works really well.

Joe

[peteski]

Great minds...   I tried this a few years ago with our trucks hoping I could launch a line of Styrene shots of our trucks and couplers for the detailer market.  We can get good shots of the outside detail but when the parts are ejected the bottom of the journals split open when they are pushed past the cone inserts.  Styrene is very stiff and splinters pretty easy when molded like this.   We already do them out of Celcon which is a brother of Delrin.  I tried ABS too but the pressure setting to get them to fill caused a lot of flash.  I think there is a market for "kits" of trucks molded like I did the HON3 trucks we produce.  These pivoted when going over rough track and works really well.

Joe

Interesting . . .
But doesn't styrene come of many different formulas?  I know from experience that clear styrene is most brittle (like the stuff jewel boxes are made from.  But I have also built many automobile model kits (1:24 scale) and I have seen a many different hardnesses of styrene being used for the car bodies: from as brittle as the clear parts to almost rubbery.

Maybe you could add some sort of plasticizer the the styrene to make it flexible enough to prevent splitting while being ejected?

[Chris333]

A friend of mine who works at an injection molding place tells me styrene comes as a liquid in 55 gallon drums. Wonder what makes it solid?

[wazzou]

A friend of mine who works at an injection molding place tells me styrene comes as a liquid in 55 gallon drums. Wonder what makes it solid?

Weird, I always assumed they were pellets that got heated to a liquid, then injected.

[peteski]

A friend of mine who works at an injection molding place tells me styrene comes as a liquid in 55 gallon drums. Wonder what makes it solid?

Actually styrene is a liquid.     https://en.wikipedia.org/wiki/Styrene  The problem is that we have this need to shorten names such as "gas" instead of gasoline and "styrene" instead of polystyrene.  So we are misusing the name styrene because it is more convenient to pronounce.  Same with gasoline: Gasoline is a liquid instead of being gas. 

[Chris333]

Sounds simple to me:

Polystyrene results when styrene monomers interconnect. In the polymerization, the carbon-carbon pi bond (in the vinyl group) is broken and a new carbon-carbon single (sigma) bond is formed, attaching another styrene monomer to the chain. The newly formed sigma bond is much stronger than the pi bond that was broken, thus it is very difficult to depolymerize polystyrene. About a few thousand monomers typically comprise a chain of polystyrene, giving a molecular weight of 100,000–400,000.

 

[muktown128]

Gasoline is actually a blend of aliphatic hydrocarbons.

Styrene is a monomer and is liquid.  It has a very foul odor and is hazardous.

Styrene monomers are polymerized (reacted together) using heat (and probably a catalyst or initiator to start the reaction) to form polystyrene.

Differences in the flexibility of styrene (polystyrene) could be due to molecular weight differences or plasticizers added for flexibility.

This is definitely not something that you would want to try at home.

Scott

[nkalanaga]

Most injection molding machines do use polystyrene pellets, for the reasons Scott gives - nobody wants the raw styrene sitting around, and the pellets are MUCH easier to handle in a common factory.  We use various "resins", including ABS, at our auto filter/manifold factory, and they all come in pellet form.  The molding machines have a hopper, and the pellets feed from there.

Originally we got them in large boxes or drums, and filled the hoppers with a bucket.  After a year or so, they installed a pneumatic system.  The pellets come in a "tank" truck, the highway version of a pressure discharge covered hopper, or in a container on a dump chassis, which uses truck air to blow the pellets into silos.  From there, the various resins go by pneumatic tube to the molding machines. 

Until I saw it, I didn't know they made dump chassis for containers.  The front lifts just like a dump truck, and the pellets pour out the back of what looks like a standard box container into a hopper, where they're moved by air to the silo.  The container must have a small door at the bottom, because the main doors stay closed, while the hopper covers the lower part of them.

[Chris333]

My friend makes a lot of carbon fiber items. I think the styrene is part of the resin around the fiber. As carbon fiber itself is just a sheet like cloth is.

[MK]

I think they use epoxy for carbon fiber resin and not styrene as styrene offers no strength.  At least that's what I'm used to for carbon fiber parts for (model) airplanes.

[ednadolski]

Along with some work on my ever evolving switching layout I set about weathering my NdeM MP15.  Trucks were dry brushed with AK tints, followed by several coats of clear Micro Flat with more tints stippled on.  I also used their oil stain and dark rust for accents.  I was surprised it ran after all the painting...but it did 

JOe

Nicely done!  Really captures that grimy/rusty/pitted texture 

Ed

[SkipGear]

Beautiful!
What kit is this?
~Bruce

It's a scratch bash based on the Walthers Bus terminal kit (HO). The only thing I am using from the kit is the windows, the back wall, the base and some roof panels.