W&U Tramway coach, using 3D Printing and the Cameo cutter

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Bufferstop
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Re: W&U Tramway coach, using 3D Printing and the Cameo cutter

Postby Bufferstop » Sun Dec 10, 2017 4:16 pm

Hope someone is building a great big fire, a mammoth takes a bit of heat to spit roast. I went way and did a bit of tweaking on a copy of the file, and surprised myself how easily you can modify a created object. I probably didn't do it the easiest way, I did it the way I could think it through. Doing my measurements on the trial print, with some axle cups pressed in, I decided the inside of the frames needed to be 5.5mm further apart. As I didn't want the frames to be any thinner the outside surfaces had to be 5.5mm further apart as well. So it went like this
highlight nearest surface.
click on it with the pull tool and pull,
in the box that shows how far you have pulled it type 2.25mm and hit return.
Spin the whole thing around and repeat for the other side.
Manipulate the image with the spin and slide controls to get a clear view of an inside surface.
Click on it with the pull tool, push and type in 2.25mm.
Repeat for the other inside surface.
Lo the sideframes are now 2.5mm further apart.
Here's a shot of the screen at that stage
DSM20.jpg

and here's the next print still attached by its "Brim" to the bed.
DSM21.jpg

As you can see the bed is covered with masking tape, the makers supply 6" square patches (for the American market) but masking tape is just as good if you press the joins down very firmly. It helps the print stick to the bed during printing, and is far easier and less likely to cause damage if it all goes wrong and needs scraping off. Only happened once so far, when I experimented with printing glazing bars straight onto transparency. Next up, the bogie cleaned up, trimming away the brim and smoothing where it was. Then I poked a 2mm rod through the axle holes and forced in bearing cups, once they were started in the hole I put it over a thick washer with about a 4mm hole and pressed the bearing in with the flat and of my tweezers. There's just a perceptible bit of sideplay, the bearings aren't going to fall out, they are an interference fit!
DSM22.jpg

There's still a bit of fettling to do along the top edges, but this rolls so well, (kept rolling out of shot,) that I'll go straight to printing a second one.
The next stage will be printing the detailed sides, springs axleboxes etc, so I have a bit of experimenting and learning to do, I'm more a straight lines and round holes sort of designer so it may be fun.
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Re: W&U Tramway coach, using 3D Printing and the Cameo cutter

Postby TimberSurf » Sun Dec 10, 2017 4:37 pm

Would not have been better to print in black?
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Re: W&U Tramway coach, using 3D Printing and the Cameo cutter

Postby End2end » Sun Dec 10, 2017 5:32 pm

You really have grasped the new technology with both hands Bufferstop. :)
I couldn't even consider building a loco from a kit let alone scratch build rolling stock so all power to your modelling spanish archer! :D

(by Spanish archer I mean... El Bow :mrgreen: )
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Re: W&U Tramway coach, using 3D Printing and the Cameo cutter

Postby Bufferstop » Sun Dec 10, 2017 11:38 pm

TimberSurf wrote:Would not have been better to print in black?

Indeed it would, but just like the ink cartridges for cheap inkjet printers cost an arm and a leg, the people who made my 3D printer have buried a chip in the centre of the spool to be able to charge whatever they like for the plastic, but it goes an awful long way, this coil of white will last a l_o_n_g time and paint is cheap. By the time I've got through this reel, I might have found how to cheat their system (it won't be too clever I'm sure) or I'll have passed the printer on and bought something more sophisticated. I already have candidates to take it on, two little technology vultures, out to prove that girls do like science, and can write better code than grandpa. What chance do I have?
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Re: W&U Tramway coach, using 3D Printing and the Cameo cutter

Postby Bufferstop » Thu Dec 14, 2017 11:31 am

This is likely to go cold for a bit. I have to do some experimenting to find out; firstly how to draw leaf-springs and their shackles, and then how much detail it's worth including when I've seen the results from the printer. I think I'll be creating them as a component then merging them into the existing bogie sides, which is going to take me into having to use the work-around because I'm using the dumbed down version of the software, or explore some of the other programs available.
As an indicator of the way this technology is going, my printer, which was considerably cheaper than the Prussa i3 which I believe was used for the book I referred to; looks like a finished object not a Meccano prototype; - and seems to give finer finishes than some of the photos of finished models.
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Re: W&U Tramway coach, using 3D Printing and the Cameo cutter

Postby Mountain » Thu Dec 14, 2017 11:44 am

Would it be an idea to mix 3D printing with resin casting? You could pick up detail via the casting method by copying something that has the right look, and use the 3D printing for the framework to support it on? It could save time in the long run.
It may not work as planned, but it is a possible idea to save time.
Enjoying 7mm narrow gauge.

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Re: W&U Tramway coach, using 3D Printing and the Cameo cutter

Postby ElDavo » Thu Dec 14, 2017 3:52 pm

Nice work bufferstop. You are certainly getting good results from your printer. What is it by the way?

Cheers
Dave

P.S. there are some clues as to how to create leafsprings in the book. It's not as difficult as it looks. ;-)

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Re: W&U Tramway coach, using 3D Printing and the Cameo cutter

Postby Bufferstop » Thu Dec 14, 2017 5:54 pm

Hello Dave, first off it's the DaVinci Mini W, the bright orange one. The W bit is pretty useless, as it looses the settings as soon as it's switched off, so you have to connect it to a PC when you next power it up. The lines of the slices are less noticeable than those in some of your photos, but every surface has a very fine textured feel, glossy smooth isn't in its vocabulary. I'll be cribbing madly from your book when it comes to the springs and axlebox.
I'll need to find some way of strengthening the bond between the overlay with the details and the blank bogie sides. Experiments so far suggest it's not the easiest stuff to glue. 'The heads of the bearing cups protrude through the sides so that will give me two dowels, but less than 0.5mm deep, so I may introduce a 1mm hole in the end of the bolster and a matching hole in the overlay then insert a tightly fitting rod and cut it off flush.
If I get the bogie to work, then at some point I would like to try a wagon frame similar to the old Peco "sprung" frames. The springing was only down to one layer of the injection moulded spring bearing on the underside of the solebar. The flexibility of the cut away brim suggests leaf springs could be made in some scale.
I have a friend who's just taken delivery of a new Prussa in kit form, I'll be interested to see if there's any improvement in resolution. I mentioned the disaster I had with the attempt to print onto transparency. I've found some intended for inkjets, not lasers, I'm hoping that the extruded filament is still hot enough to melt the surface when it hits it. If it does then it's printing pre-glazed window frames. I'd already printed the frames very thin then putting them in a carrier along with one sheet of a laminating pouch, don't bother trying! I might do better with a domestic iron, but I know better than to try it with the one in the cupboard.
I tried to make head or tails out of 3D Printing for Dummies using Sketch Up but couldn't get my head around it's scant regard to scale when starting, that's when I bought your book, could see how the process worked and started looking out for an affordable printer, even if it was only going to be for practising on.

Thanks for you interest

John W
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Re: W&U Tramway coach, using 3D Printing and the Cameo cutter

Postby Bufferstop » Wed Jan 10, 2018 10:34 pm

Back after the break, managed to get the odd hour here and there finding out how to draw bogie sides and discover what they printed like. The ones that Dave did in the book were 7mm scale and looked quite good. At 4mm scale let's say it's not worth struggling to put much detail in. Fortunately even the prototype bogies are difficult to see. I've sussed out how to do the chassis and floor and how to compensate for the tendancy of long narrow things to curl. Photo session in next couple of days once I've cleared the Christmas decorations bris from my desk and workbench.
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Re: W&U Tramway coach, using 3D Printing and the Cameo cutter

Postby Bufferstop » Fri Jan 26, 2018 3:24 pm

Whoops away longer than I intended, life has a habit of getting in the way of modelling. Still I've sussed out most of the limitations of a cheapo 3D printer, and worked out ways around it's limitations. I'm going to print the coach as a kit of parts to use along with some sheet material where I want straight and rigid components. or a realy smooth surface is called for. Here are the bits
Kit.jpg

By using styrene sheet for the walls and clear polycarbonate for the glazing I should have a box which will hold the flexible floor/chassis straight. Watch this space.
I've already started collecting bits for my next project, build a motor bogie. I've go the motor, gears, wheels and bearings, lets see what's possible.
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Re: W&U Tramway coach, using 3D Printing and the Cameo cutter

Postby Dad-1 » Sat Jan 27, 2018 10:08 pm

You can make anything if you work at it.
From what you say it comes to making one, to find how to
make a decent second one !!

Geoff T.
Remember ... I know nothing about railways.
viewtopic.php?f=22&t=32187 and Another on viewtopic.php?f=22&t=28436&start=60&st=0&sk=t&sd=a

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Re: W&U Tramway coach, using 3D Printing and the Cameo cutter

Postby Bufferstop » Sat Jan 27, 2018 11:36 pm

That's what R&D is all about, well it is when I'm doing it. When the actual fabrication involves no more effort it becomes a cycle of testing which way the tricky bits come out best. You build the prototype to find out how to do it, then you think of an alternate method and do the next one completely differently. Playing with the CAD software you can build some amazing things that were just about impossible to make until 3D printers arrived. I went to a local exhibition (where Blair, B308, was exhibiting) Chas Ward of CW Railways was there with his printed NG bodies. He had a loop of chain without a split link. Printed already joined up, he probably incorporated some very thin spacers which would break away when it was twisted.
Next job is stick the bits together, I've got the underframe and floor joined together and mounted on the bogies, the sides come next.
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Re: W&U Tramway coach, using 3D Printing and the Cameo cutter

Postby Mountain » Sun Jan 28, 2018 2:23 am

It is coming along nicely. Though what I make is not 3d printing, and the style of coach you have is different, I sometimes have an easy way to strengthen my coaches by adding longitudinal bench seating. I was thinking, if the internal structure of your coach could be made in such a way as to be adding some strength to the structure? Maybe you could use some solid metal as a weight which doubles up by adding some rigidity?
Enjoying 7mm narrow gauge.

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Re: W&U Tramway coach, using 3D Printing and the Cameo cutter

Postby Bufferstop » Sun Jan 28, 2018 12:24 pm

Mountain it so happens that the prototype coach had longitudinal bench seating. The frame I created to join body to floor will provide an edge on top of which an L shaped extrusion will sit, forming the seat and backrest as well as being an additional stiffener. By the way I've discovered how to print net curtains! Anything less than 0.4 mm thick in natural coloured PLA comes out as a very fine translucent web so I'm saving the larger of the flat sections if I print with a brim, to help hold the object to the bed. If you choose to have a brim the slicing and printing program adds a very thin flat snap-off sheet around the item. It seems a waste to remove and discard it.
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Re: W&U Tramway coach, using 3D Printing and the Cameo cutter

Postby Bufferstop » Fri Mar 02, 2018 4:18 pm

I haven't given up on this process, I just keep getting diverted into other (mainly non railway) things. The last few days have been taken up sanding back to bare wood an old clothes horse, or "maiden" in my wife's Northern English. The strips of cotton webbing that served it as hinges haven fallen to dust and I decided it ought to get a repaint before I replace them. It just about could claim "antique" status and it's too useful to throw out as folded in two it just slots into a space between kitchen cupboards. Putting that aside here's a photo of my work bench today,
Workbench.jpg

Two jobs on the go at once, at the back two versions of the coach, one I'm 3D printing base, sides, ends etc.and behind it one in which the body will be a perspex box with sides cut on the Cameo cutter and laminated. It's actually a very old technique, I first saw described in "Narrow Gauge Modelling" By Don Boreham. He cut his layers from manilla paper covers, drawing each layer from the same master on each sheet, I'll use styrene sheet. The covers were left over from the books of Registration Certificates, which he filled in and handed out daily as Chief Registrar at Somerset House. I'll have to buy the styrene sheet, but the software will save me having to repeatedly draw the same outline.
In front of the coach parts is the next job, "Build a motor bogie" the tub full of gears is one of the bumper packs from Hong Kong via Ebay, there are five or six basic types in different diameters and bore sizes going up in 0.5mm steps, biggest job is finding ones that are the same size. Working out how to plan the gears I re-discovered something I must have learned fifty years ago. How to work out the distance between the shaft centre lines for a pair of meshed gears. It's quite simple really
Measure the overall diameter of each gear, put the gears in an easy mesh and measure the distance over the two. Subtract half the diameter of each gear from the distance over the meshed pair and whats left is the distance between centres. Works for worms too. I seem to remember that getting the mesh right involved feeding a strip of writing paper between the gears whilst they were pushed together. If the paper was neatly creased the mesh was about right. if the bottoms of the creases were split they were to tight. I expect if I had gone on to mechanical engineering rather than electronics I might have learned a complicated formula for getting the correct mesh, I'll stick with the bit of paper.
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