# HFC tanker



## Burl (Jan 2, 2008)

Threw this together, just to see if its feasible:










Here's the prototype: http://www.rrpicturearchives.net/showPicture.aspx?id=3572397

I can get the extreme dimensions from shipcsx.com. I have been fiddling with getting the tank dimensions to match the shape, and the capacity the prototype is stenciled for. 

I know the capacity is 17,595 gallons.

I'm assuming the outside radius of the tank is 60", just because the proportions seem OK to the eye, and 10' OD is a nice, round number. I'm also assuming there is 4" of insulation, a 1/2" steel inner cylinder, and a 1/4" steel outer jacket. All that would give me a 53 1/4" inner radius.

If I'm doing the math right, the volume would be the volume of a cylinder, plus the volume of an oblate ellipsoid (see http://www.web-formulas.com/Math_Formulas/Geometry_Volume_of_Ellipsoid.aspx) where c=1/3 of the radius - which means I drew a half sphere of 60" outside radius, and shrunk it in one direction by 1/3.

That would be: Total volume = (4/3)*PI*a*b*c + PI*r*r*l
Where a=b=r and c = r/3.

If I'm plugging in the numbers right, I'm getting this:
(4,064,445.23192 - ((4 / 3) * p * 53.25 * 53.25 * (53.25 / 3))) / (p * 53.25 * 53.25) = 432.6

4,064,445.23192 cu in = 17,595 gallons. That's telling me the main cylinder should be 432.6". The drawing looks OK based on those numbers. That's also giving me a 72 inch width for the outer jacket segments. Is there anything else I'm missing here?


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## Scott (Jan 29, 2008)

Burl, great start. The devil is in the fine detail. Will you be manufacturing with the top dome or that be added after for ease of construction?


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## Burl (Jan 2, 2008)

After my last experience with rotational casting, the manway cover will be a separate piece. I probably should have attempted a car like this first, since the tank should be ideal for rotational casting.


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## Burl (Jan 2, 2008)

Had to tweak a couple things. The wheelbase was too short, and the ends weren't quite right.


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## Burl (Jan 2, 2008)

I'm far enough along now to shrink some of the components to 1:29 & have them printed. These will become patterns for RTV molds. They are scaled in Sketchup by 0.03448 (1/29), then again by 1.01 to account for shrinkage in the resin. Unless its a part I intend to mold twice, then its scaled by 1.02 the second time to account for two generations of molds. I will probably order these tomorrow (after I've stewed on it overnight). They'll all be open-faced molds, except the saddle - it will be a glove mold.


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## Scott (Jan 29, 2008)

Are you putting the slight cant in the centre as per prototype??? Or is it just too slight to have the mold show this? Looks good anyway and look forwards to seeing the outcome for casting. Merry Christmas mate.


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## Burl (Jan 2, 2008)

I wasn't, until you said that. I kept thinking it was distortion from my camera, or my mind was playing tricks on me. Trinity doesn't have any public drawings (that I could find), but American Railcar had some of a comparable car & it looks like about 6" of deflection in the middle of the tank. So far, changing that will only affect a couple parts I've drawn. Glad you caught that early on.


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## rdamurphy (Jan 3, 2008)

This might help:


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## SD90WLMT (Feb 16, 2010)

Ok guys...it's Xmas...but keep this in mind!!

Some tanks....many more of later designs have the obvious "V" tank shape for drainage....
Many do not have this feature tho..
It is not on every tanker...across the board ..

So ... which tanker have you chosen to model here..as a prototype. . Burl??
That would be what's important.... I do see many of this type...but it is only one of many tanker concepts running on rails!!

M.C.


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## Scott (Jan 29, 2008)

That's the beauty of this site, people will contribute handy feedback to make modelling better. With so much equipment and the endless variations on prototypes. Someone somewhere will have a plan or pic that you yourself won't know or doesn't have.


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## Burl (Jan 2, 2008)

I didn't think about it, but I guess you can't tell from the link to the prototype photo its a corn syrup tanker. Here's my own photo:










I photographed this car in Cookeville, TN around 2004. I assume it was high-fructose corn syrup for Russell Stovers. That plant closed a couple years later & I haven't seen any more of these down this way.


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## SD90WLMT (Feb 16, 2010)

Your posted pix both appear to be shallow "V" versions Burl..

Actually I missed your link...thank you!!

They don't look terribly long either...

Dirk


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## Burl (Jan 2, 2008)

I think I have all the parts drawn now. Here's what will be printed in acrylic & used for RTV molds:










These parts will be printed in nylon:






























I debated on doing these in acrylic, but since they won't be visible in the final pattern I decided to have them also printed in nylon. Its hard to see in the rendering, but the top face has a slight tilt. They will join back to back, and plug into a 4" OD tube (from Plastruct). This will give me the V shape in the main tank body. I figured this would be less error prone than trying to set the miter saw to 1.something degrees.


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## Scott (Jan 29, 2008)

Your 3d print set up looks pretty good. Hope it all works out well from Shapeways.


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## armorsmith (Jun 1, 2008)

Burl,
I would say that the 'cant' Jonesy refers to is not a 'feature' included by the manufacturer. I would suggest that this is a natural deformation induced during use and operation. Although entirely possible to replicate this in model form, the result may not be worth the effort to accomplish it. I have no doubt in my mind that the Trinity engineers have accounted for this in their engineering of the car and subsequent FEA.
Good luck with the car, although not a modern standard gauge modeler, I am always interested in techniques.
Bob c.


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## Burl (Jan 2, 2008)

Right after I posted that, it occurred to me printing two rings and gluing them together was an unnecessary step. So I will have this printed instead:










Bob: I'm agreeing with Jonesy on this one. Other drawings of similarly sized tank cars show the same V shape. It would make sense for corn syrup to have such a design. Also, since the car I photographed was on its way back from Russell Stovers', I think its safe to assume it was empty. You can draw some reference lines with your favorite photo editing software and see there's clearly a V in the prototype's body.


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## SD90WLMT (Feb 16, 2010)

Clearly - deforming - is not brought on by use..

If this was trully happening..there would be many leaking and broken tankers across the country!!

Tankers are built with a broad "V".. as a means for draining the last drop...
I see many tanks with a sump below the main tank that serve this purpose also...without the bent tank look..the sump becomes the low point..


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## armorsmith (Jun 1, 2008)

I think we may be talking about different points on the tank. I now see you were talking about the bottom of the tank. I was referring to the 'swayback' in the top center. Being a mechanical designer I understand the strength of materials and there are devices that are 'engineered' to flex. So long as the flex (swayback) does not exceed the maximum yield strength of the material the deformation is acceptable.
I'll be quiet now and go back to my corner and watch.
Bob C.


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## SD90WLMT (Feb 16, 2010)

No Bob...ya can't leave!!! ;-)

What you say ..I agree with. As a fabricator, I can say your correct in your lessons.
What I want to clarify is based on your basic design guidelines.
Materials can flex...and have useable limitations...without failure..considering your decription of flex and material stretch here...I tend to think a tank car with a straight tank, in a loaded condition would very well have some induced flex in the tank. We would see this in uniform deformation, over the length of the tank...causing a very broad and gentle arc ... or curvature..
The broad "V" depicted here does not represent this typical loaded deformation, as each 1/2 section is still infact a very straight segment...not showing any typical expected deformation!

Please .... don't go...the lessons are good for all! 
;-)


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## Burl (Jan 2, 2008)

Civil conversation is always welcome.

Here's a link to an American Railcar tanker of a similar capacity that I was talking about earlier: http://www.americanrailcar.com/pdf/RailcarManufacturing/TA-Nonpressure-20800.pdf


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## SD90WLMT (Feb 16, 2010)

I like the clarity of the called out data for the tank itself..

... 1/4" slope , per foot...

...pretty clear.!!

Nutha nice car Burl


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## Scott (Jan 29, 2008)

On the bright side, we saved Burl here $$$ for production. Also on hair too....lol


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## Burl (Jan 2, 2008)

Jonesy: my OCD thanks you.


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## armorsmith (Jun 1, 2008)

Burl, Jonesy,
Great find on the car outline. I would never have thought that the entire car would have been canted to the center. Pitching the bottom tangent to effect drainage makes sense. I don't follow the logic of the top tangent though unless the car is a cylinder with a miter cut joint at the center. Oh well, live and learn. Thanks guys.
Bob C.


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## Scott (Jan 29, 2008)

Thanks guys, I didn't realise that a innocent query was going to be such a discussion point. I am glad to see it has helped. Paying it forwards the help I have received since being on here.


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## Burl (Jan 2, 2008)

Anybody have any thoughts about how the cut in the middle of the tank shell, where the V is formed, is made? I assume it would be cut flat, and then rolled into a cylinder. I wonder if there's a formula for it that some of the machinists out there would know. 

I can use Sketchup to intersect a cylinder at a slope with a square, but I don't know any way to "unroll" the cylinder to know what it should look like flat. I guess if I can't come up with something better, I'll print a ring with one face sloped, and wrap card stock around it to trace the line.


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## armorsmith (Jun 1, 2008)

Burl - The higher end solid modeling packages will 'unroll' a cylinder of any shape. The issue is laying out the flat pattern. IF we assume that the tank is two mirrored parts of cylindrical shell, mitered to fit at the center it is a no brainer for my cad software at work. My suggestion would be to provide me the OUTSIDE DIAMETER you are going to use either in prototype feet/inches and the scale you are going to use, or the actual diameter in inches. That along with the proposed slope/angel and the rest is easy peasy. Can you handle AutoCAD files in either DWG or DXF format?
Bob C.


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## bnsfconductor (Jan 3, 2008)

Burl, 
I can't tell from the prototype photos but I recall that the top of these tanks were sloped the same as the bottom. I used spot a corn syrup facility that got these cars on a daily basis, but there are slight differences between car manufactures. As a side note when these cars are spotted for unloading they are first connected to a steam line that heats up the car so the syrup will flow.


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## Burl (Jan 2, 2008)

Bob: 

Half of the tank body is a 4” OD cylinder, 7.473” long, with a rotation such that one end is 0.207” lower than the other. Somewhere in the neighborhood of 1.6 degrees of rotation, so the sum total between both cylinders would be about 3.2 degrees.

The final OD of the model will be 4.138”, but I will have to build up that from a 4” OD tube.

I should be able to open DWG or DXF in Sketchup.


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## armorsmith (Jun 1, 2008)

Burl,
Cool. Monday will be first day back after being out with the flu, so am sure it will be hectic. Give me a day or two and I will PM you for an email address.
Bob C.


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## Burl (Jan 2, 2008)

After I stewed on it for a while, I realized I forgot to draw up the placards. They are probably too thin to print separately, and I got lazy, so I will have the whole mold box printed:











I also figured out (by trial and error) that it is cheaper to have the ladders printed ten at a time, versus two at a time with the rest of the nylon parts:











By doing this, I was able to keep the cost of the rest of the nylon printed parts under $60 per car. That's assuming Shapeways doesn't jack up the prices again on me.

I believe these to be the last of my revisions, so I placed an order for all the printed parts this morning, virtually ensuring Shapeways will have a sale tomorrow...


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## Scott (Jan 29, 2008)

Neat idea with the mold box, maybe you should have a side able to detach so you can remove a casting. I'm not sure how much flexing your mold box will stand.


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## TheFishGuy (Feb 1, 2011)

Subscribed...


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## Burl (Jan 2, 2008)

It's not the first time I've printed a mold box. Thin stuff comes out easy. Thicker, and I would build the box myself anyway.


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## Burl (Jan 2, 2008)

While I'm waiting for my parts to come in, I'm making molds for the outer tank jacket. I'm trying to get the ripples a little more subtle for this car than I would for a boxcar, or a hopper, or something where the sheet metal is flat. I'm thinking the outer tank jacket will be thicker sheet metal on the prototype and not as prone to "oil can".


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## armorsmith (Jun 1, 2008)

Burl,
Files sent
Bob C.


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## bnsfconductor (Jan 3, 2008)

Burl, 
Are you planning on a flat wrapping for each car? Or is the mold going to be a circular mold? These tanks have quite thick insulation for the heating, and steam lines, so that outer layer might be thinner than you think. I don't recall seeing any more or any less damage than regular boxcars, but I wasn't ever planning really close attention either.
Craig


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## SD90WLMT (Feb 16, 2010)

I'll throw in my thoughts on tank cars..

I have ...a couple tank cars I started years ago...the basic structure is built from heavy PVC pipe... couplings ...& and rounded over caps for ends..
My thoughts were to over lay these base tubes with sections of 0.010" sheet to create the offset overlaps often seen on tank cars..

My other observation..and thus comparision to your thoughts Burl is these outer coverings are not of a base structural make-up...the main inner tank does this..as such there would not be any or very little wrinkling or stress induced in the outer skins...on box cars & hoppers, the thin side skins are part of the load carrying design...and become distorted under loads as a whole with the entire structure. This is similar to those outer coverings on a boiler of a steam engine...

Sure...mishaps occur....dents are left behind...but I'm not seeing a lot of the wrinkly waves seen on other cars..

Keep striving onward...thanks for your incredible projects Burl.

Dirk


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## Burl (Jan 2, 2008)

Craig: the body will be rotationally molded as one piece. The OD of the tank needs to be around 4.18", so it will be built up from 4" OD Plastruct tubing.


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## SD90WLMT (Feb 16, 2010)

Well.....so I went picture wandering....

Looked at many styles of tank cars....from various random owners..

What I saw is interesting...not unlike what I get to actually see rolling by...

Regardless of wrapper design...I saw no damage or flexing or waves or deformation on any car I looked at..
I saw one end cap ...ever so slightly punched... the result of some small blunt object...small dimples at best!

While most cars I observe fall in the stepped overlap skin group...I know some wrappers must be built using a butt-joint design....either way...the only real significant thing might have been circular deformation at these seams.
The step-overlaps are assembled by placing the first wrapper over the end cap, next installed is the third wrapper, followed by the second wrapper...over lapping..and sitting higher by the skins thickness...over both seams on the 1st n 3rd wrappers...and so on....
These seams have a tendancy to shrink and pull inwards in their completed form...slightly....

Cars for the most part do not show much damage or stress aging from use like most other pieces of equipment do.

Dirk


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## Burl (Jan 2, 2008)

The prototype photos I have only show a very slight wave, and that visible with a glossy surface. I don't think any sheet metal is dead flat, and I'm not going for an exaggerated oil can on this one. But I also don't want it to look like styrene wrapped around a perfect cylinder.

Dirk: here's an unusual car: http://www.americanrailcar.com/pdf/RailcarManufacturing/TA-Nonpressure-29000.pdf

This doesn't have anything to do with what I'm building, but it makes me wonder if the spiral wrapping is continuous for the length of the car. If it is, how do you deal with the middle of the tank where the slopes meet?


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## SD90WLMT (Feb 16, 2010)

Morning Burl...

I found the wrapped car rather intriquing! It does seem to defy the possibility of what it is..I tried searching for other views of the car...it seems to be a new and recent concept, as that is the only picture to be found...every search lead back to the manufactures site.

I played in my head the process of a spiral wrapped tube. Actually it may be easier than it looks, and only requires the proper placement - therefore pre-planning - on where the wrapper lands as it passes around the middle section. I even thought about using a roll of tape...a long cut paper strip...something to pretend wrap around a pipe..just to play with it...I'm pretty convined it will work.

I found another pic with a large diagonal indentention...near the mid point of the tank car....rather well oil canned!
So..we wait on you...to see what's in your minds eye!!

Dirk


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## SD90WLMT (Feb 16, 2010)

Now ya got me watching tank cars more closely....

A bunch just went thru here...lots of "Procor" tanks..
Various lengths..
Various style ends..
One had 2-3 times the slope factor of all the rest..which where the more typical 1/4" per foot slope...
All mostly faded black n weathered...

D


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## SD90WLMT (Feb 16, 2010)

And I'm still watching tank cars.....
Was a great day of it too! Xrews are working on tie replacement ...under my turnout for the siding here....
Train orders are slow...running heavy stuff right over the turnout..with loose ties..like 5 - 10 mph..
Been great to watch trains move at a slower pace....
...and I was up close today..getting 4 water trips caught up.

So I sees one of them spiral wrapped tank cars pass by...and honestly..I have never noticed the difference before.
I saw 2 of them today!! They are wrapped continuous from end to end...looking like one long piece of metal sheet.
But to answer your ? Burl. A pie cut is made mid point...to allow for the slope on each tank 1/2. The now seam, is welded together...completely around the tank!!

Sometimes ya gets lucky!!! Oh..on same train...rear dpu...was a old ex SOO SD60, now CP...which was rebuilt a couple years ago!!! I stopped...it stopped...took 16 pix on F.M.side of loco!!
I'm just sure it will become a future project for me!!!

Dirk


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## Burl (Jan 2, 2008)

Dirk: 95% of what I see around here are LPG tankers - mostly black. Occasionally I see a white, or blue, sometimes a gray. Of course, the odd ball colors are what everyone wants to model.


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## Burl (Jan 2, 2008)

Trying to figure out how to build the mold box while I wait for parts...


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## SD90WLMT (Feb 16, 2010)

Granted most tankers are black. Those two spiral wrapped units I saw are also black.. I do see colored tank cars everyday..yea... blue, grey, white & pea green...plus some two tone colored cars!

Our model world creates a chuckle at times...
Unit grain trains run nearly all grey cars...with a green CNW in every unit that passes...some pale yellow also..not much variety there....yet my growing collection of grain cars is just the opposite. Nearly completely all in color, with just a hand full of grey cars! !

Oh..well...the trains must roll...


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## Burl (Jan 2, 2008)

After I stewed on it for a while, I realized my mold box was going to be unbalanced if I built it like I had drawn it. I also saw that my fill hatch wasn't going to work - too hard to get the plug out of the mold. If I've learned anything about resin over the years, its that once part A hits part B, you better be quick!

Also, by changing the fill hatch, now its big enough to let me pour all the RTV into the box without needing any other access holes, except a couple small vents.


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## Scott (Jan 29, 2008)

Looks good Burl - going the whole shebang of the tanker. You won't need to weight it as its solidity will give you the weight as required. Will you be pouring the resin as the mold spins on a lazy susan to distribute the resin evenly?


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## Burl (Jan 2, 2008)

I'll be using this contraption:


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## Scott (Jan 29, 2008)

Neato Ralph. I see now - as the mold rotates - the resin coats the mold and evenly distributes as it cures.


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## Burl (Jan 2, 2008)

I see... you thought I was going to make it a solid casting. That would have been heavy! Who is Ralph?


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## wchasr (Jan 2, 2008)

Am I missing something in the interpretation of "HOW" the real railroads build the tankers with the slope? 

Figuring out the flat pattern and coiling the tube wouldn't have been a difficult engineering job back in the day. 

My first thoughts for creating this from PVC was to cut the angle on my miter saw and rotate one half of the cut pipe 180 degrees and then glue it back together. Then add the details? Am I missing something simpler?

Looking forward to following your progress Burl.

Chas


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## Burl (Jan 2, 2008)

Chas: does your miter saw allow you to set angles in 10ths of a degree?


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## armorsmith (Jun 1, 2008)

Sure Does Burl.....Trial and Error....


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## Burl (Jan 2, 2008)

You must have fancier tools than I do.

An other reason I hesitate to try this by trial and error is because Plastruct 4" tubing is expensive. PVC pipe, while cheap, is too big.


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## SD90WLMT (Feb 16, 2010)

Yea...tubing costs money....how long are the pieces of tubing?

It is easier to cut a wedge than one might consider...even with some trial n error adjustments ...

I'm thinking a sled is easiest....I used a custom one I built for cutting grain cars..
With a support wall or fence to hold the pipe in place...simply sliding a spacer outward will create infinite angles..and one would find the perfect fit needed.


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## Burl (Jan 2, 2008)

Dirk: that's a good idea as long as you have a saw that can do a 4" cut. In fact, if you had mentioned that before I ordered my parts, I probably would have tried it.


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## SD90WLMT (Feb 16, 2010)

Sorry....I run 10", 12", & 14" band saws...

Slips my mind at times....have not been to your "Man Shop", ta see what ya can work with!!!

Frankly...even any decent wood saw..chop versions can work with that size pipe....I often cut larger pvc and abs pipe on one..usually a 10"...

;-)


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## armorsmith (Jun 1, 2008)

Burl,

I was being a bit of a smarta$$. I agree that tubing from Plastruct is expensive and mistakes cost money. Another method that will work is to calculate a shim thickness at a distance from the blade to provide the required angle on the piece. The danger of this method is that the workpiece is now not as secure as being properly placed on the cutting table. I have done both with success, but caution is paramount.


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## SD90WLMT (Feb 16, 2010)

Those seemingly expensive tubes from any supplier...need not be used just for trial an error cuts....any scraps of any material can very easily be used in place .. and instead of..using the final product for the final cut...

There is a reason sleds are nice to use....better stability of the cut object...


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## Burl (Jan 2, 2008)

Dirk: to answer your previous question, the tubing is about $37 for a 3' section.


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## SD90WLMT (Feb 16, 2010)

And after making a mold...a box ..resin....and a finished tank body...
....what are ya looking at? ... $$$

;-)


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## Burl (Jan 2, 2008)

Will let you know when I'm finished. ;-)


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## Scott (Jan 29, 2008)

Neato Ralph is a old Aussieism / Euphanism for top work mate. LOL cultural and slang differences. I had thought you were going to cast the ends separate and then bond them together instead of going the whole tank.


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## Burl (Jan 2, 2008)

Put my mold box together this afternoon:


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## Burl (Jan 2, 2008)

Some of my printed parts came in last week. Here's the first casting of the side frames. I'll make three more and make a gang mold from that, so I can cast enough for two trucks at a time: 











Here's the bolster to go with it, printed in SLS nylon:


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## CliffyJ (Apr 29, 2009)

Fascinating to see all the problem-solving going on throughout this thread. 

Great job Burl!

Cliff

PS, thanks for your new avitar-pic!


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## Burl (Jan 2, 2008)

Here are the final truck castings. I tried to take a picture of the bearing caps, but since they're printed in clear acrylic, they didn't photograph well. I will have to wait till my wheels come in, and I can paint everything, to get a better picture. These will have music wire springs in the back row (for functionality) and SLS nylon springs in the front (for looks, to scale).


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## Scott (Jan 29, 2008)

Wow, looks awesome. Will have to see now when the wheels come in how it tracks and if they run well.


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## Burl (Jan 2, 2008)

My patterns arrived from Shapeways last week. I made up most of my first generation molds over the weekend. Here's the first casting of the saddle:










I think I went to low on the poly count on the tank car ends. They came out with very visible concentric circles. I should have taken a picture, but I didn't. I primed and sanded three times to get a smooth surface. Here's the first casting:


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## Burl (Jan 2, 2008)




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## Scott (Jan 29, 2008)

Impressive first cast, should fit nicely with the tank component.


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## Burl (Jan 2, 2008)

After getting the 4" tube from Plastruct, I found the wall thickness to be thinner than expected. I had some 3.5" tube already, and it measured around .070" wall thickness. I think the larger tube was somewhat thinner. The SLS nylon ring I had printed didn't fit exactly snug, so I wrapped it with a few layers of tape to get a tight fit.










I kept going over in my mind what would give me the best bond between the printed ring and the tube, and I was leaning towards epoxy or gorilla glue. I have a phobia about weak glue joints. I especially didn't want to get this thing almost ready to mold, then fumble it & bust the seam. Then it hit me: expanding foam.

I wish I had thought of that before I cut the tube. As it is, the ~.060" thickness of the plastic lets it flex & makes it very difficult to get a true cut on the miter box. Hind-sight is 20/20 though.


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## Scott (Jan 29, 2008)

What if next time you use expanding foam in the tube, then cut it to shape would that help? It may mean not so much flex. Or even ice, fill it with water, freeze it and then cut. Remove ice and let dry - wouldn't have so much give then. Just an idea.


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## Burl (Jan 2, 2008)

Oh, the scenarios I go over in my head with ice... would it even be possible (now that I’m married) to find that much space in the freezer? Would the expansion of the ice during freezing burst the tube? And how much splatter would there be from the heat of the chop saw. I’m sure my obituary would just say “he passed away at his residence”.


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## Scott (Jan 29, 2008)

I was thinking bandsaw - but that is too uneven. 

Unless you use a woodlathe and turn some timber into a round shape to fit the inside diameter. Glue in with some basic / el cheapo wood glue then cut, once cut - you wet the glue enough to remove the insert and then cleanup prior to fitting.

Another option would be to use a sanding machine (similar to this - https://www.machinemart.co.uk/shop/product/details/clarke-cs4-6d-belt-and-disc-sander) utilising the guide at a angle to get the shape you want.


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## Burl (Jan 2, 2008)

I've got a sander like that. It works pretty good, but the speed is a little too high (will melt the plastic if you're not careful).


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## Scott (Jan 29, 2008)

Hmmmmm. 

Are you are able to slow the speed of the sander? 

If the speed is slowed down that would prevent molten plastic. Or a little at a time - that'd have to be your first cut and the square cut at the end done second, so as to not end up with a shorter than required tank.

Or, maybe using the sanding guide idea. Have a jig set up to hold the tube in position and at the correct angle. 

Make a wide sanding board from a piece of timber and glued on sandpaper (1 x rough for shaping, 1 x fine for clean up) about a half inch either side of the tube to allow for movement. Have the board about a foot long to be used as a large flat rasp to shape the angle. Have handles or cleats added to give best grip and application of the sanding board when you pass each time.

This way it gives you better control - no melting, shattering or cracking of tubing. Can be done at your pace and checked every couple of passes to remove burrs and check for accuracy in your work.


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## SD90WLMT (Feb 16, 2010)

Scott & Burl,...

I use band saws almost exclusively for cutting plastic for my models....
I use 15T Blades...
I do very high precision cuts....

I set the saw up for accurate vertical lines...

Do not short change what a band saw can do as a tool .... and their ability to produce parts for our models!
I have a machinists back ground....I make very consistant parts...

Ice is too much work..plus waiting....plus drying..lost time..

Dirk


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## Totalwrecker (Feb 26, 2009)

I like my band saw too! 
I also have a water cooled lapidary sander! Nothing like dripping water to prevent the heat dragging edges of molten! 
I was going to link to one but new they are way expensive, mine's 10 years old. Back then my 12" disc flat lap was about $300 now they are way more! But used lapidary equip is available. 
Shouldn't be too hard to rig something up in a plastic tub. Spray a little adhesive and wet n dry sand paper and you are good to go. Tilt slightly to drain...

ps; My saw gets wet enough in the rain, but I don't think I want water inside it, every where an ice chip can be flung....
John


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## Scott (Jan 29, 2008)

These are all good points, as the old adage goes - there's more than one way to skin a cat. Lol. Unfortunately I don't have the money to buy a reasonably good bandsaw. The one I got needs some tweaking to stop the variance of 3 - 5 mm.


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## SD90WLMT (Feb 16, 2010)

Sounds like a guide block issue for the blade Scott...

Mine primary saw is a old Sears...10" - 3 wheel unit..
Small portable...added a broad wood base to stabilize it...

I keep the small guides tight...but barely free to move the blade between..it has rollers for behind the blade..they just touch...

Had this since 1985... a few minor parts over the years...still runs great...used more than all my other band saws, And most of my tools combined..

Cost.... $100.oo. value....priceless. .my first choice to make parts on! I only use a larger saw if the piece is larger than the 10" will handle...like cutting whole car bodies apart. Or loco shells...

Get it fixed up buddy!!

Dirk


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## Scott (Jan 29, 2008)

For a basic Metabo I thought it'd be accurate. It's leaps and bounds better than the Ryobi they sell at Bunnings for $280 which is only good for cutting kindling. I have made adjustments to the Metabo, a mate made a aluminium insert for the table and that bought it down to 2-3mm variance. Still not satisfied I'd prefer 1 - 1.5mm variance. The guide is too loose, and doesn't stay in a locked position - some person designed it so the wheel moves it up or down and doesn't lock, also the rollers in the guide are too small and loose. I miss the one I used when I did my carpentry course over 20 yrs ago, ok an $8,000 dollar machine but so good to use and .5mm variance. Another Tweekend project (sigh).


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## Burl (Jan 2, 2008)

I took the easy way out on fitting the wrapper in the middle. When I had the connecting ring printed, I also printed a half ring. I know there's a formula for calculating the intersection between two cylinders, but this seemed less error prone. My gut was that any slight variance in the wrapping underneath would have a bigger effect on the wrapper, and that seemed to be true (the main tube got two layers of poster board wrapped around it to bring it up to size).

The wrapper gets taped around a blank with the half ring:










The disc sander makes quick work of the raw edge, which is resin. Since SLS nylon doesn't sand well, its easy to tell when I've sanded far enough:


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## Burl (Jan 2, 2008)

Just so you don't think Scott is crazy (fast-forward to 2:50): http://youtu.be/bLSsLUfG0ho?t=2m57s


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## Scott (Jan 29, 2008)

A nice simple way to achieve the end result. Impressed by the Trumpet vid. How well does it all marry up? Will the ends fit the way you planned?


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## Burl (Jan 2, 2008)

Some more progress on the castings. Here's the final bolster & saddle:












And here they are together: 












I'm pretty happy with the fit on this. I don't think I could have ever gotten it to fit this well if I had made it by hand. 


I don't have much to show yet on the main body. I glued the wrapper on last week, and almost got discouraged enough to peel it off and start over. My problem was that I tried taping it on while the glue set, and I never could get the edges to lay flat enough. So I came up with this:












Its the mold I used to make the wrapper, trimmed slightly to fit the diameter of the tank body. I wetted the edges of the wrapper with thin CA, then wrapped the rubber mold around that, with a layer of sacrificial styrene, then band clamps on top of all of it. The perk to using the old mold was that CA won't stick to RTV, so I could clamp it down extremely tight & not worry about it not coming off later. 


Currently, I am sanding & filling on the body. I'm being very picky with it at this stage, because I don't want to have to sand & fill on the finished tank casting. Maybe I'll have something to show for it later in the week.


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## Scott (Jan 29, 2008)

Coming along very nicely, looks good.


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## Burl (Jan 2, 2008)

I still have a couple small voids I want to fill, but here's the main tank. I think at this point I have filled, sanded & painted at least 5 times. I was hoping the wrappers' slightly different thicknesses would give enough of an impression of weld lines that I wouldn't have to do anything else to it, but all the sanding has pretty much negated that. One more layer of paint, and I'm afraid they'll disappear all together. I will probably use some Archer .030" weld bead decals to compensate.


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## Burl (Jan 2, 2008)

My end castings ended up being about .040" bigger than the body, so I re-molded & the shrinkage from that process took up most of the difference. The 2nd generation of castings was only a hair larger than the tank body, but I still had to do another round of Bondo & spot putty to even out the seam. Here it is after a fresh coat of paint. I still have a couple spots to fill & sand, but I'm almost there.


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## Burl (Jan 2, 2008)

Since the body has a slight V shape, I had to do something to account for that in the connection between the body and the bolsters. I made a temporary jig to align the bolsters.












They're hard to see, but on top of the bolsters are two wedge shaped castings. The patterns for these were 3d printed, using the body angle to derive the angle of the wedge. They are tacked to the bolsters with two tiny drops of CA. A larger quantity of CA is put on top of the wedges, then the body is aligned on top of the whole thing.












After the CA has set up, the wedges are popped off the bolsters with a flat tipped X-acto blade:












Then they're beefed up with some .040" styrene. This should make it easy to keep the production castings in alignment when assembling the finished model.












And here's a dry fit:


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## Burl (Jan 2, 2008)

Starting on the final coat of paint today. Decals (weld beads) have been applied, and all mounting holes have been drilled. I'll have to let this dry for a couple days before I paint the top. I'd hate to get smudges on it from sitting in the cradles.


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## Burl (Jan 2, 2008)

Started the pouring the mold this week:


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## Burl (Jan 2, 2008)

Pulled the mold out of the mold box today.

The aluminum foil worked fairly well as a release. I still had to take a couple sides off to get the whole thing to release. One thing I learned from my previous project: the mold box needs to be able to be disassembled from the outside.

I wish I had put some stock in on the ends for spacers. As it is with the mold length equal to the inside width of the box, it is difficult to get in and out. This got fixed by cutting about 1/8" off one end of the mold.


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## Burl (Jan 2, 2008)

While trying to figure out how to make up for the shrinkage of the mold material, and how to get the mold out of the machine, I had the idea to use plastic sheeting. By wrapping the mold before I close up the box, it makes up for the shrinkage incurred when the RTV cured. The packaging doesn't say what its made of, but the sheeting acts like polypropylene in that resin doesn't stick to it. It also gives me something to hold onto when I'm taking it back out:










The first casting had too much resin heaped up on one side, and I pulled it out too early anyway. Strangely, I feel better about losing the first one. The last large mold I did poured perfectly the first time, and it took me months to figure out how to get another good one out of it.










My theory for the first failure is that the resin was too thin, allowing the majority of it to congregate in the bottom, instead of sticking to the walls. It accumulates heat too quickly this way, and once it begins to kick (accelerated by the heat), it stops flowing all together.

To compensate, I added micro balloons to increase the viscosity. It seemed to work. In the second casting, you can see where it has kicked. Each dark wave is one pour. This was four pours, three ounces each, giving a total of twelve ounces of resin. This photo is a 15 second exposure in a dark room, with a flashlight held to one end of the casting:










In the next casting, I will try increasing the viscosity with more micro balloons. I will also insert a straw in the pour hole to help the resin flow in faster. That should give me a little more working time.


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## Burl (Jan 2, 2008)




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## Scott (Jan 29, 2008)

Whooooeeeeeee Earl! That's looking pretty good. Once she's got a coat of paint and decals that is gonna be a total ripper of a model.


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## Burl (Jan 2, 2008)




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## John Allman (Jan 2, 2008)

Ok, I'm impressed. That looks terrific.


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## Burl (Jan 2, 2008)

I ordered some wheels from The Train Department (W203-26L) a couple weeks ago, and they came in yesterday. 




























I don't know if they intended these for 1:29, but they came in pretty close. The price is also very reasonable. I am seriously considering going with these for my kits. I will add some weathering (rust) later to give them some more depth, but for now I wanted to photograph them the way the I'd be shipping them.


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## ewarhol (Mar 3, 2014)

Sharp looking truck Burl. When will the tankers be ready for purchase/shipping? Estimated price?


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## Burl (Jan 2, 2008)

If I go with these wheels, which I think I will, then I have all the figures I need to come up with a price... let me go through my numbers and get back to you later today.

I'll have to order some more wheels, so I'm probably looking at 2-3 weeks until I could ship anything.


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## Burl (Jan 2, 2008)

I ran all my numbers, and the total price for the kit is going to be $275 (+ s/h). This includes trucks and couplers. You will have to order the printed parts from Shapeways separately - they will be $75 per car.


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## ewarhol (Mar 3, 2014)

Will your website be updated when orders can be placed? Or an announcement here?


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## Burl (Jan 2, 2008)

You'll be the first to know.


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## tmejia (Jan 2, 2008)

Can I be second?

Looking forward to one of your HFC Tankers.
I think they look great.

Tommy
Rio Gracie


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## Burl (Jan 2, 2008)

Absolutely.


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## Burl (Jan 2, 2008)

I put the finishing touches on the instructions today. Now I'm just waiting on decal paper.


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## Burl (Jan 2, 2008)

Got the first one boxed up and ready to go: 










I have parts for several more that I can ship next week. After that I will make them up as needed, but there will be a 2-3 week lead time. 

Anyone interested can contact me through my website: http://burlrice.com/


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## Scott (Jan 29, 2008)

Great work Burl. Looks very professional.


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