7mm Mike Hopkins workbench - GNR Artic Coaches

M

Mike Hopkins

Member
I have been working on this project for quite some time now the whole thing is designed in Fusion 360 using the sheet metal function as well as solid modelling for 3D printed for castings and coach bodies.
I was at first going to do the whole thing by 3D printing the chassis bogies and bodies but after a numerous attempts at trying to perfect a method of joining roof and chassis halves together put the project down, my Formlabs printer wasn't big enough for the job. What I had built was put to one side and as time passed I noticed the chassis, body side and roof were all distorting, more than a year had passed and I decided it was time to revisit this project, this time I was etching the chassis and with the purchase of an Anycubic Photon Mono X I could print the roof and coach sides in one piece with out joins.
I accidently dropped one of the first build coach bodies it hit the table from where I was moving it from and only from a short height it smashed into 6 pieces. The resin had become brittle after only approx a year and a half so I offer this warning to anyone using Formlabs standard resins for bodies of wagons, coaches, engines etc the life expectancy isn't that long, the engineering resins have a longer life expectancy.
Anyway back to the project, I've not actually started building yet but have sent the CAD files to PPD a week ago and after I received the quote placed the order for the etches yesterday.
My 3D printer is going mad printing the Wax Resin prints for castings whilst I write this post, they will be sent for casting in brass early next week.
This is a render of Diagram 134, it's what I'm starting with. Both the coaches are the same so I'm only paying for one etch master for the chassis as I want to make sure I have got all the slots and bend widths correct before I send other coach chassis for etching

D134-01.png


A view of the chassis assembly
D134-02.png

Here are some screen shots of the etch pattern from Fusion 360 and the final CAD file in this sequence is from QCAD as you cannot colour the drawing in in Fusion, so I need someway of arriving at a the correct information for the etching company.
D134-04.pngD134-05.pngD134-05b.png

Hopefully the build starts here in two or three weeks when the etches and castings have been produced.

If anyone wants to know more about sheet metal in Fusion 360 I can start a topic in the CAD section there is a slight issue with this though, it has been discovered you cannot export a drawing in the right file format unless you have purchased the full version or you know someone who has and is willing to do it for you.
I know not everyone knows me but I'm willing to help with this if you require.

Finally a couple of renders of other coaches in the pipeline after this one.
GNR-Coach-01.pngGNR-Coach-02.png

Mike
 
N

neaston

Western Thunderer
.".. in this sequence is from QCAD as you cannot colour the drawing in in Fusion, so I need someway of arriving at a the correct information for the etching company."

I have used PPD for some years now and send them a black and white EPS of front and back of etch with vertical and horizontal scale line say 100mm. I think they would also accept the same as a pdf. They have always been very helpful and quick compared to some companies I have used before.
Good to see you are on WT to give the benefit of your expertise.
Nick
 
simond

simond

Western Thunderer
I use PPD for work, they are prompt and professional. We use red & blue DXFs To define the etches.
 
M

Mike Hopkins

Member
Hi Rob and Nick its good to see familiar people here.

Thanks Tony I hope the models turn out as good as the CAD renders.

I have used PPD on and off now for probably about 10 or 12 years, pre that for a few years I use to do my own etches. I invested in my own spray etching equipment.
I Placed an order with a company for an A4 etching system this included every thing I needed to start metal etching, but changed the order to include the next size up double sided exposure UV lightbox as the starter kit only had single sided and its size was somewhere between A5 and A4. Anyway when my order actually arrived they had sent me a complete system for A3 this included all the chemicals and it was huge compared to what I had ordered. I ended up keeping it at no extra cost but after a few years of occasional use decided it was to messy and a too long winded process to continue with. I still have it sits in my workshop occupying space.
As some of you know I use to use other CAD systems for my modelling, about a year and a half ago I moved to Fusion 360.
The process was a bit more involved than Fusion 360. You couldn't make the flat patterns into an assemble without exporting them in a different file format first and then re-importing, with this process the link is the lost with the 3D model so any changes to the master model is not updated in the assembly of the flat patterns. Fusion changes that every thing is linked so changes in the 3D model are captured all the way down to the etching master pattern just by opening the file and updating the relevant part or assembly. Those that use Fusion will know what I'm on about, those that don't use 3D CAD sorry if its sounds a bit double dutch.
I also use to do a front and a back using just black or white (depends on your background colour) as that is what I did when doing my own etches and yes PPD do except it in that format, but every etching company suggests the black, red, blue and white, some will only except files as that and will charge you quite a bit extra to do it for you, but why waste your time doing two images when you only need to do one.
 
M

Mike Hopkins

Member
I've been wondering what to do about the bogies, my initial thoughts whilst CAD modelling them was to 3D wax print and have them cast in brass but might prove expensive, I'm now wondering whether to redesign and etch the frames or to 3D print in high temp resin and then whitemetal cast.
Has anyone got any experience and or preferences as my experience is limited to a couple of Kirk kits and injection moulded plastic bogies.
 
simond

simond

Western Thunderer
I’m much impressed that you can design etchings in 3D CAD and link the 2D masters to the assembly in Fusion, if I’ve understood correctly. Even Solidworks Pro doesn’t offer that capability, which has me designing in 3D, then creating 2D etch masters either by redrawing (tedious, potential invitation to Cap’n Cockup) or export/import (also tedious).
 
M

Mike Hopkins

Member
simond said:
I’m much impressed that you can design etchings in 3D CAD and link the 2D masters to the assembly in Fusion, if I’ve understood correctly. Even Solidworks Pro doesn’t offer that capability, which has me designing in 3D, then creating 2D etch masters either by redrawing (tedious, potential invitation to Cap’n Cockup) or export/import (also tedious).
Click to expand...
I was impressed as well when I did it, I've been using Inventor Professional and Siemens NX professionally and neither of them support it.
 
LarryG

LarryG

Western Thunderer
Some years ago, friend Ralph Jackson (Jackson-Evans) and I cooperated in producing castings and etchings for buses. He handed my patterns to a jeweller for casting in whitemetal. I learned he could make rubbers from plastic patterns, but I continued to make up patterns from brass etchings thickened with brass sheet. There was little is any shrinkage from this jeweller, which was something of a revelation after being used to making patterns slightly larger than the finished size!
 
simond

simond

Western Thunderer
Mike Hopkins said:
I was impressed as well when I did it, I've been using Inventor Professional and Siemens NX professionally and neither of them support it.
Click to expand...

it will certainly be an option when I retire and presumably won’t have access to SW any more. I guess learning a new language is good for the brain…
 
M

Mike Hopkins

Member
I was going to show the build of the chassis but I got so engrossed in actual modelling I forgot about the photos.
Any how the build of one of the chassis etches and castings went flawlessly.
This is what I've constructed so far
GNR-D134-artic-01.jpg
GNR-D134-artic-02.jpg
GNR-D134-artic-03.jpg
There are a couple of castings with small holes, but they do look really bad close up but are hardly noticeable with the naked eye.

GNR-D134-artic-04.jpg

GNR-D134-artic-05.jpg

20220420_134220.jpg
I had to solder tubes onto the end of the truss rods so that I could fix in place with nut and bolt castings, thought it was going to be really hard but once I realised I had do drill a hole into the tube first and then push the rod in, solder, drill through the tube centre to remove the end of the rod and then trim the tube to size to form the rod eye it was really easy. The tube is 1.6mm dia. and the rod is 0.9mm dia. the nut and bolt casting has a pin dia. of 0.7mm.

I had printed and obtained castings for the two gas tanks suspended from under each chassis but they weren't up to scratch so now going to construct from tube as I discovered 13/32'' dia suites one of the tanks and 15/32'' dia the other also will have to obtain new castings to plug the ends of the tubes as the tanks have concaved ends.
 
Last edited:
Nigel Yule

Nigel Yule

New Member
Mike Hopkins said:
I was going to show the build of the chassis but I got so engrossed in actual modelling I forgot about the photos.
Any how the build of one of the chassis etches and castings went flawlessly.
This is what I've constructed so far
View attachment 161472
View attachment 161473
View attachment 161474
There are a couple of castings with small holes, but they do look really bad close up but are hardly noticeable with the naked eye.

View attachment 161475

View attachment 161476

View attachment 161477
I had to solder tubes onto the end of the truss rods so that I could fix in place with nut and bolt castings, thought it was going to be really hard but once I realised I had do drill a hole into the tube first and then push the rod in, solder, drill through the tube centre to remove the end of the rod and then trim the tube to size to form the rod eye it was really easy. The tube is 1.6mm dia. and the rod is 0.9mm dia. the nut and bolt casting has a pin dia. of 0.7mm.

I had printed and obtained castings for the two gas tanks suspended from under each chassis but they weren't up to scratch so now going to construct from tube as I discovered 13/32'' dia suites one of the tanks and 15/32'' dia the other also will have to obtain new castings to plug the ends of the tubes as the tanks have concaved ends.
Click to expand...
Mike
This is a lovely model, I am planning on modelling some GNR Artics, are you in a position to supply the castings?

Regards
Nigel Yule
 
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