How Good Are Drawings ?

[Compound2632]

Here's my method:

1. Fix solebars to floor, making sure the axles are at right angles to the solebars. Test all runs true.

2. Fix one end to ends of solebars and floor, making sure all is square and the bottom of the headstock is aligned with the bottom of the solebars.

3. Trial fit of one side and other end to make sure parts fit together snugly - some careful trimming / skrawking / filing / sanding (method to personal preference) of the floor may be needed.

4. When happy, fix other end in place, checking all is square. (Sometimes I fix a side to the end but not to the floor to help alignment.)

5. Then the sides.

6. Then brakes etc.

Resist the temptation to assemble the body as a box first.

Basic assembly of a wagon from a decent plastic kit (Parkisde, Slaters, Cambrian) takes no more than 30 mins allowing time for solvent to harden after each step. 

[relaxinghobby]

Thanks Compound I was off RMweb last night as I was trying to figer out the kit. Somehow in my Airfix kit educated naivete I thought that the sides and end would fit perfectly. I've always had problems with these kits especially with centering the parts and getting them square.

 

Idea read the instructions!

 

The wagon sides were only tack glued and fell apart under the stress of trying to flex them into position around the floor and wider axle boxes.

 

So now I am following the instruction steps one by one, solebars to floor then add an end and then a side etc, etc. The floor is slightly too narrow, should I file down the bevelled corners so they fit the floor or glue a piece of packing material between the floor and sides? Assemble omein 30 minutes! it takes me days with all the gluing and pulling apart the wonky bits again. Maybe longer if I give up.

 

 

All my white metal combined W irons and axle boxes are thrown into a bag together and mixed up, there are different sorts.

The trouble I am having with the cattle van chassis could be that there is a slight difference between the types and I have used 3 of one and one of the other.

 

I'll try 4 of the same on the cardboard coal wagon.

Edited May 5, 2018 by relaxinghobby

[Compound2632]

The floor is slightly too narrow, should I file down the bevelled corners so they fit the floor or glue a piece of packing material between the floor and sides? Assemble omein 30 minutes! it takes me days with all the gluing and pulling apart the wonky bits again. Maybe longer if I give up.

 

Ah that is where it does start to become a bit of a black art with some of the older kits produced with less crisp mouldings - some early Cambrian and Parkside for example. Look carefully at the mitre joints between sides and ends to see what gives the snuggest fit then be guided by that. I find Slater's floors need shortening just a fraction - 0.5 mm or so - but width-wise are good; with Cambrian I've mostly been kit-bashing (to make my Huntley & Palmer wagons). If the floor does seem narrow, a piece microstrip is the solution - I know I have done this but can't remember for which wagons...

 

I should also say that I am using a solvent - Slater's MekPak - for all plastic work and a cynaoacrylate - Rocket Max - for brass or whitemetal to plastic.

[Jol Wilkinson]

Rather ironically, assembling wagon kits is something I find easier to do in P4. Because it is usual to fit some sort of compensation or springing (although not everyone does with short wheelbase vehicles or bogies), the w-irons are usually installed and aligned to the largely completed body and the cosmetic springs and axleboxes added later.

 

It takes longer and costs more because you have to buy the w-iron etches but also has the advantage that the wheelsets can be "sprung" in or out for painting, etc. Some wagon kit designs also have separate  spring castings as in relaxinghobby's photo which also makes things easier, but that isn't usually the case with moulded plastic kits.

[Compound2632]

Rather ironically, assembling wagon kits is something I find easier to do in P4. Because it is usual to fit some sort of compensation or springing (although not everyone does with short wheelbase vehicles or bogies), the w-irons are usually installed and aligned to the largely completed body and the cosmetic springs and axleboxes added later.

 

It takes longer and costs more because you have to buy the w-iron etches but also has the advantage that the wheelsets can be "sprung" in or out for painting, etc. Some wagon kit designs also have separate  spring castings as in relaxinghobby's photo which also makes things easier, but that isn't usually the case with moulded plastic kits.

 

There is of course absolutely no reason why you can't do this in 00 too!

 

And you've got a convertible wagon barring some tweaking of the alignment of the brake blocks.

Edited May 5, 2018 by Compound2632

[Guy Rixon]

So now I am following the instruction steps one by one, solebars to floor then add an end and then a side etc, etc. The floor is slightly too narrow, should I file down the bevelled corners so they fit the floor or glue a piece of packing material between the floor and sides? Assemble omein 30 minutes! it takes me days with all the gluing and pulling apart the wonky bits again. Maybe longer if I give up.

 

I suggest packing the floor with microstrip. Any exposed, un-planked strip visible inside the wagon can represent the inner edge of the curb rail,which was typically wider than the side planks.

 

I tend to approach plastic opens like this:

 

0. Do all the detailing and painting of the interior that I want because it's so much easier to do it before assembly. Scrape clean the surfaces that need to be glued.

 

1. Fix the floor to the ends, mounting the floor on top of the headstocks. If the floor is slightly too short, I pack it with microstrip. Let it set hard, checking that the ends stay parallel.

 

2. Dry-fit the sides to the assembly and check the fit at the mitres. If the floor is forcing the mitres open, file down the floor edges. If the mitres are tight but the sides don't touch the floor, pack the edge of the floor with microstrip. In either case, if I have to adjust, I aim to make the floor slightly - maybe 0.5mm each side - wider in the middle than at the ends. This offsets the tendency for the side to bow in at the centre. Typically, the adjustment is unequal at each corner, because I have the floor slightly off-centre and the ends not quite collimated. A few tenths of a millimetre are correctable here.

 

3. Fit one side, fettling the mitre faces as I go. Let it dry hard (too tricky to adjust both sides at once).

 

4. Fit the other side.

 

5. Adjust the solebars to fit the assembled wagon, trimming or packing as necessary.

 

That sequence blows the 30-minute budget for elapsed time, but doesn't add much labour and, for me, avoids a whole string of monocoque-ups with badly-fitting parts.

 

Also, I fit brass axleguards as per Jol's post, so I'm not affected by moulding errors in the positions of the wheel bearings.

[Compound2632]

I suggest packing the floor with microstrip. Any exposed, un-planked strip visible inside the wagon can represent the inner edge of the curb rail,which was typically wider than the side planks.

 

I tend to approach plastic opens like this:

 

0. Do all the detailing and painting of the interior that I want because it's so much easier to do it before assembly. Scrape clean the surfaces that need to be glued.

 

1. Fix the floor to the ends, mounting the floor on top of the headstocks. If the floor is slightly too short, I pack it with microstrip. Let it set hard, checking that the ends stay parallel.

 

2. Dry-fit the sides to the assembly and check the fit at the mitres. If the floor is forcing the mitres open, file down the floor edges. If the mitres are tight but the sides don't touch the floor, pack the edge of the floor with microstrip. In either case, if I have to adjust, I aim to make the floor slightly - maybe 0.5mm each side - wider in the middle than at the ends. This offsets the tendency for the side to bow in at the centre. Typically, the adjustment is unequal at each corner, because I have the floor slightly off-centre and the ends not quite collimated. A few tenths of a millimetre are correctable here.

 

3. Fit one side, fettling the mitre faces as I go. Let it dry hard (too tricky to adjust both sides at once).

 

4. Fit the other side.

 

5. Adjust the solebars to fit the assembled wagon, trimming or packing as necessary.

 

That sequence blows the 30-minute budget for elapsed time, but doesn't add much labour and, for me, avoids a whole string of monocoque-ups with badly-fitting parts.

 

Also, I fit brass axleguards as per Jol's post, so I'm not affected by moulding errors in the positions of the wheel bearings.

 

Virtually the opposite of my sequence! Chacun a son gout. I would argue that the merit of my method is that one can make sure one has a good rolling chassis at an early stage. However, where I have scratch-built using etched brass axleguards, I have tended to fit these at a late stage though there has been plenty of trial fitting to get the solebar back-to-back right etc.

 

Whatever sequence one uses, the key thing is to make sure that everything that should be at right angles is, and everything that should be parallel, is too.

Edited May 5, 2018 by Compound2632

[relaxinghobby]

Thanks for the help guys, the body is now done.

I had to widen the floor with a strip of Microstrip about 5 thou, I cut it from a take-away coffee cup lid.

The sides were a tiny bit too long so I cut about 1/4 off each end ( sounds more precision than it actually was, I just match the side to th efloor and atarted cutting and then sanded the bevel back a bit, hard to keep a square edge to the side.

 

So my order of assembly was; sole bars and buffers to floor untill a good rolling chassis was achieved, then an end, then a side after triming, then the other side then the other end

The corners have needed a little bit of filler on the inside.

 

 

This picture taken in bright early morning sunshine before going off to enjoy a promised warm Bank Holiday Monday. But it puts the black plastic in shadow, so difficult to see that side of the kit.

Everything provided on the sprues now built, I've got to add couplings and a ballst weight underneath.

 

I'm still persevering with the white metal axel boxes. Last try if this does not work I'll use

fold up brass W-irons.The picture shows three in position, when the glue is set hard I'll postion and fix the final one with UHU.

I'm out of bearings, I may be able to get some on Thursday when I am in town? So I hope the white metal one will work.

Edited May 7, 2018 by relaxinghobby

[relaxinghobby]

 

I got it to work at last, the white metal axle and W-iron mouldings all lined up straight and running, which is a good thing as I don't have any more pin point bearings yet to put into fold up brass alternative.

 

 

Couplings fixed under the coal wagon, I just build up towers made of layers of plasticard, varying the layer thickness until I reach the correct level. It's all glued in with styrene solvent at the moment, as it dries out the couplings will fall off as they are a hard plastic not affected by the solvent, then I'll re-attach them with superglue.

 

 

The corner plate is made from some thin red styrene, from a coffee cup lid. I've pressed in some rivet detail, hardly visible at distance is it worth adding or will it just disappear as you look from further away.

 

How should I add the rest of the ironwork.

 

 

There will be a single braked wheel only as on the photo I'm adapting one from the kit.

[relaxinghobby]

 

One side done, brakes on, I mean the single brake is glued into position, the ankle level cleaning holes should have vertical iron bars which would be almost invisible in 4mm scale, I’ve cheated and put in a single horizontal strips, no way could I think of away of modelling such tiny features. Maybe they represents a later modification on the prototype.

Should I bother to impress rivet head detail in the red plastic bracketry, if so will it show up?

 

Back in post #37 Quarryscapes showed us his etch for a 2 mm scale version of this van. Did you build a model from this how did te vertical bars in the cleaning opening turn out?

Edited May 14, 2018 by relaxinghobby

[Guy Rixon]

The vertical bars could either be done properly, which is crazy hard, or by cheating.

 

The proper way is to drill the upper and lower rails 0.3mm and insert lengths of 0.3mm wire. The problem is getting the alignment right, given that the rails to be drilled are made as part of the whole side and the top rail can only be drilled by going through the bottom one and hoping that the drill stays in line.

 

The cheat is to mark out the spacing of the bars on the inside and then notch the sides with a knife or scrawker. The wires are then glued into the notches. They probably won't fetch up exactly on the centreline of the timbers but this may not matter too much.

 

Neither method works well after the van is assembled.

[Guius]

With regard to the veracity of engineering drawing, it's been my experience that very seldom does a working drawing issued to various departments of an engineering concern, as an instruction to build, honestly reflect, for the most part, the finished article. We as modellers, are not privy to the 'evolution' which has take place implicit in any project planning operation. Many engineering companies would produce an 'As Fitted' group of drawings for the customer, (or 'end user' in New Speak) often diverging from the original drawings considerably.  So, we have to work with the information we can gather and make educated guesses to fill in the empty spaces best we can.

 

Guy

[relaxinghobby]

 

I would agree with Guius about published drawings, as soon as I started scratch building from them I've found problems and discrepancies. Also in the models we are using different material thickness’s and the wheel dimensions are different especially in 00 where they are more inboard and thicker than on a scale drawing.

I found for me I need to start with developing my own drawing from the published one. Here a CAD application makes making a technical drawing much easier especially were many repeated parts are required. A drawing is definitely part of the design process of the hope for model.

See the drawing for my cattle wagon in post #33, it was designed for all the parts to be cut from 20 thou or 0.5mm plasticard or cardboard.

Building it has taken much longer than drawing it, after building it there are several things I would now do differently.

[relaxinghobby]

 

Finally done, next step is painting probably a light shade of grey. Those buffers were difficult they are sprung ones from Gibson, whilst I was assembling them I could not get them to work and by the time I had glued them to the buffer beams they where glued up solid. Does not matter with the Bachmann couplings though. Feels like it could do with a bit of weight, a piece of metal inside the central part of the wagon should do the trick.

 

Next wagon I have made a drawing of is an early gunpowder wagon I found on the Furness Railway website. I'll try this in cardboard as I designed all the bits and piecies, sides and end etc to be made from half millimeter thick card.

 

Edited May 20, 2018 by relaxinghobby

[relaxinghobby]

Card board wagons and CAD

 

 

I found some pre-used fold up W irons in the bits box or is that the failed and abandoned kit box from which I salvage bits. It was a bit wonky but the straighten out OK.

Needs a bit of packing between the W irons and floor to make the body higher. So how high to make this wagon? Is it old enough to have a buffer height of 3ft 3in or the later standard 3 ft 6in?

The Scots wagon just seems too small, the planks don't seem wide enough and the buffers are too narrow. There is not enough space between the sole-bars to fit fold up W irons in so to make it big enough I calculate the drawing has to be enlarge to 116% of it's present size. Good old CAD, with Inkscape I can easily do this and print out the new enlarged version of the drawing. And start cutting out the bits again.

 

 

Some progress with the gunpowder wagon, it did not work out very well, I did not allow properly for the thickness of the cardboard, I had to cut down the floor width to fit between the sides and also trim the internal cross piecies, so I was not so good at 3D visualisation as I thought. So carry on as practice makes more skillful?

Edited June 4, 2018 by relaxinghobby

[relaxinghobby]

Well this kinda demonstrates that your models can only be as good as your prototype information.

I’ve been fiddling around with the Inkscape drawing programme to modify the drawings to widen the body, I don't have an original diagram or drawing so they are all guess work and an artistic interpretation of photos of Caledonian Railway Diagram 22 wagons on the Caledonian Railway website, the first incarnation was oblivious too narrow as it was not wide enough to except brass fold up W irons.

They need 24mm of space between the solebars so I widened the drawings to take them.

I did at first just enlarge the whole drawing by 120 % but it did not look right the photos show a short wagon, it now seemed too long and the solebars were too tall.

So I redrew it, wider taller but the same length so it roughly matched another 13 foot wagon from 1875 that I found a sketch of. A few weeks off from using Inkscape and I've forgotten half of it so I made some mistakes.

The pink wagon is the new one, a mistake from hurrying the drawing modifications was the blank side, I did not reverse the planking lines from left hand to right hand, so I had to flip the cardboard, they are still there

entombed between the two sides, new plank lines will have to be drawn on by hand.

 

Extra wideness

 

Blank side mistake

 

Solebars widened on pink one

 

 

Messy sketches of older wagon types, original diagrammes found around the web.

Body now 29 mm wide, which is about 7 foot 3 in 4mm scale.

[relaxinghobby]

Despite all this modern CAD stuff to help myself think in a 3 dimensional way I have to go back to pen and paper and ruler, I've not yet managed to master a 3D modelling or CAD application.

Here are the thinking behind the layers for my cattle truck build. Post #31.

 

 

Edited June 25, 2018 by relaxinghobby

[Spitfire2865]

Despite all this modern CAD stuff to help myself think in a 3 dimensional way I have to go back to pen and paper and ruler, I've not yet managed to master a 3D modelling or CAD application.

Here are the thinking behind the layers for my cattle truck build. Post #31.

 

P1010089.JPG

 

P1010091.JPG

What program are you using for CAD and 3D modelling?  If youre a student or have the money, Id recommend AutoCAD for 2D.  Easy to learn, use, and master.  

[relaxinghobby]

On my gunpowder van I've just tried the roof after moulding it to shape over a plastic food

container which happened to be the correct diameter.

 

 

Its wrong, there is a gap along the bottom, so I'll have to cut a new one a bit wider next time.

Back at the drawing I could not have calculated the width properly, I think a proper technical drawing app would make this sort of thing easier than in Inkscape which is really an art tool for making graphic art.

 

 

This is a cardboard model, which is in some ways an easier material to shape than plasti-card I find. Fot this roof the cardboard was soaked in water for a while until it was soft and then held around the plastic pot with elastic bands until it was dry.

Edited June 25, 2018 by relaxinghobby

[relaxinghobby]

Hi Spitfire, I'm using Inkscape for 2D and trying to get my head around Blender for 3D modelling, I run a linux system on my PC but can't work out how to get Sketch Up to run with Wine the Windows emulator for running Windows apps in Linux, Ubuntu 14 in my case.

Years ago I learnt Turbo Cad 7, and I think I managed to master it but the license for that copy has long since run out and it could not really do much in the way of 3D conversion from the initial flat 2D drawing, but it was usefull for designing the cutting parts and dimensions.

Edited June 25, 2018 by relaxinghobby

[Spitfire2865]

Hi Spitfire, I'm using Inkscape for 2D and trying to get my head around Blender for 3D modelling, I run a linux system on my PC but can't work out how to get Sketch Up to run with Wine the Windows emulator for running Windows apps in Linux, Ubuntu 14 in my case.

Years ago I learnt Turbo Cad 7, and I think I managed to master it but the license for that copy has long since run out and it could not really do much in the way of 3D conversion from the initial flat 2D drawing, but it was usefull for designing the cutting parts and dimensions.

I could never get my head around anything but proper drafting programs, though thats probably attributed to my engineering experience.  Cant stand the imprecision.  

Sketchup would be a hard pass from me.  It may act like a 3D modeller but it has nothing of the like.  If youre going for free, the best Ive seen bar piracy is AutoDesk's Fusion360, which is almost like a "Solidworks Lite" aside from a few aspects I couldnt get on with.  If you download the free trial, then click the "Im using this for personal work only and not profiting from any of it" option in the license menu, itll just unlock the program fully for you.  From what Ive seen of your work, it is all non-commercial anyway.  

Does anyone you know have a valid student email? Many of the professional companies offer student licenses, AutoCAD included.  IMO, you couldnt find a better 2D drafting package.  

[relaxinghobby]

 

Internal strengthening of the gunpowder van, longitudinal set of spacers set between the cross pieces along the centre line. Weighted with ceramic beads from a Boots the Chemist microwavable pillow. Should be OK with PVA glue?

 

Roof formed bysoaking carboard and placing around a plastic food container of suitable diameter. Held in place with waterproof masking tape.

Edited July 29, 2018 by relaxinghobby

[relaxinghobby]

 

Trouble with roofs is no matter how carefully I measure them out even with the help of the Inkscape drawing programme it does not fit. So it is back to the trial and error method of offer up and trim, this is my fourth attempt. For such a close fitting roof where there is not the usual overhang of the sides I should have either built the van upside down from the roof up so to speak or made the sides and roof one piece so and wrapping the single piece of material around a former sort of like making a cab roof or a boat even?

 

I've ended up using an old wallet file as I hope they are acid free cardboard and seem to be easy to work. You can just see the faint pencil lines above the gutter joint above the GUNP---DER lettering from the fit and cut process.

 

At this stage of planning and construction I am beginning to understand the troubles kit manufacturers must have in designing build-able sets of parts.

[Guy Rixon]

If you know the radius of the roof r and the width w of the van at the cantrail, you can work out the length of the arc roof. The angle t subtended by the roof at its centre of curvature is

 

2 * arcsin(w/2r).

 

Then the length l of the arc is

 

2 * Pi * r * (t/360)

 

where t is in degrees (i.e. the circumference of a cylinder from which the roof is cut, multiplied by the fraction of a full circle occupied by the roof). 

[micknich2003]

 

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