Gauge O Guild Special Interest groups

Discussion in 'CAD Corner' started by Rob Pulham, 25 June 2021.

  1. Rob Pulham

    Rob Pulham Western Thunderer

    You may have seen elsewhere that coming up I have a test build for an LNER D2. The first build is to be a BR period build and I have a J6 chimney casting from Gladiator for it. However once the etches are proved I plan to build a second D2 for myself which I wish to finish as it was in it's early life with the LNER in lined green.

    This means that it will need the original chimney so I need to turn one/have one 3D printed or something.

    Those who are Gauge O Guild members may be aware that following on from the success of the virtual shows the Guild has been hosting some special interest session in various subjects one of them being 3D CAD/Printing. I missed the initial session a few weeks ago but caught up with it via the YouTube channel and then joined last nights session.

    Prior to joining the Zoom session I downloaded and installed Fusion360 which is the software at the centre of the 3D CAD element of the sessions.

    This morning I had a play and following a demo video done by a fellow GOG member last year I managed to draw a chimney.
    Having completed it I shared the image below with the gent who ad created the artwork for the D2 etches and he commented that the smokebox looked a bit narrow. Then it dawned on me that I had used the figure for the radius taken from the drawing and hadn't doubled it to enter the diameter. Apparently you can enter a radius figure but I haven't worked out how yet.

    So this afternoon I attempted to redraw it using the correct smokebox size.

    You will note in the image above that there are orange coloured squares. These are offset planes that I used to apply the dimensions from my chimney drawing. I managed to miss out one of the planes (for the bottom of the chimney rim) and try as I might I couldn't manage to draw any lines between the planes like I had this morning. in frustration I deleted all but the base, saved it and went and had my dinner.

    This evening I worked out how to import a drawing, resize it and then draw over it as I would in Inkscape or QCAD.

    Below are a couple of views of the revised drawing.


    D2 Chimney.JPG

    I still need to work out how to get the base of the chimney hollow like the top but you learn more by working out how.

    I am now a happier bunny.
  2. ianlbsc

    ianlbsc Western Thunderer

    Well done Rob! There is a 'shell' command in the modify area that gets most of the base hollow and then draw a hole and extrude for the last part. As you say, the more you try, the more you learn! Cheers, Ian
    Rob Pulham likes this.
  3. Rob Pulham

    Rob Pulham Western Thunderer

    Thanks Ian,

    I will have a look at that tomorrow.
  4. Overseer

    Overseer Western Thunderer

    While I wouldn’t want to stop you having fun with 3D cad, you could have made the chimney on the Unimat in less time than you have spent so far on the computer. Easier to get sharper arrises too. And cheaper if you only need one.
    Wagonman and Rob Pulham like this.
  5. Dan Randall

    Dan Randall Western Thunderer

    I’ve been trying to get to grips with Fusion 360 for about a year now, but having used TurboCAD for my 2D and 3D drawings for many years, I’m finding the learning curve extremely steep!

    I’ve lost count of the number of Fusion tutorials I’ve watched via YouTube and am really impressed with the software’s capabilities and the ease with which people (who know what they’re doing!), design stuff. It looks so much easier and faster, than using TurboCAD and I really must keep practising, gain some basic competency, then apply this to my chosen projects*.

    Ian MacCormac did an interesting tutorial on designing and printing a loco chimney a year or so ago, via the Gauge O Guild. This was fascinating to watch and I followed the various stages and achieved the required end result. More recently, Chris Walsh has done some tutorials (again, via the GoG), the most recent one, being the above mentioned Zoom meeting a couple of days ago. As I don’t do Zoom, I’ll watch this, when goes on general release in the next few days. (Both Ian and Chris were kind enough to answer some questions I’d sent them via PM, so huge thanks to them both).

    *I do have something to show for my dabblings with Fusion so far though. For Christmas, I received an Elegoo Mars 2 Pro 3D printer and an Elegoo “Wash & Cure”. (Believe it or not, I only opened the boxes about 3 weeks ago!). Anyway, having set things up, I successfully printed the “Rook” test pieces that are pre-loaded onto the Elegoo’s flash drive….
    (They were very firmly attached to the build plate and I couldn’t get them off with the supplied scraper, hence damage to the right hand one - I had to resort to whacking them with a piece of 2” x 1” timber in the end!). :))

    Impressed that a), the quality was really good and b), I’d managed to get my printer working 1st time, I remembered that I’d used Fusion, to draw a water scoop deflector dome, for the tender on my MOK Ivatt 2-6-0. The lost-wax casting supplied with the kit was OK, but the pictures in the instructions, showed a flare at the base of the dome, which was absent from the casting, so I thought I’d see if I could do it as a 3D print. This was (for me), a fairly simple excercise in Fusion and this is how it turned out….

    The flare is visible at the bottom, but I added some sacrificial material, to protect it from potential damage, when removing the print from the build plate. This can be seen via Fusion’s sectional analysis feature….
    (Mmmm, reminds me of a Jameson’s “Raspberry Ruffle”!). :))

    I was well chuffed with the end result and after cleaning, drying and removing the support structure, the sacrificial material was removed, by swirling the dome around on some abrasive paper….



    (I’m pretty sure threads are possible in Fusion 360, so I may well print another dome and incorporate a thread in the centre portion, thus enabling me to screw it to the tender from below).

    Having shown this to a friend on Friday, he reckons I should print a new water filler too. As that particular casting is already Araldited on, I think I might pass on that!


    Last edited: 26 June 2021
  6. Rob Pulham

    Rob Pulham Western Thunderer

    Thanks Fraser, I do intend to have a go at turning one as well. I recently bought a small fly cutter for the Unimat and I am looking forward to giving it a whirl.
  7. JimG

    JimG Western Thunderer

    I use a sharp blade like a Stanley knife blade to get under the corner of a piece on the building plate. This gets the corner lifted enough to let the blunter scrapers supplied to get under the part and do the heavy lifting. A well sharpened wood chisel would do the same job.

    Len Cattley and Dan Randall like this.
  8. simond

    simond Western Thunderer


    having printed it, I’d be tempted to tap the one you have. That boss looks ideal. Of course, you might need an M4-and-two-sevenths tap to fit the hole if you didn’t plan for this :)

    I wish you guys would stop showing all these fancy toys. I need to master the ones I’ve got before I get anything new!

  9. mickoo

    mickoo Western Thunderer

    Welcome to the world of replacement 3D prints, it's infectious and before long you'll be throwing all those (s)crap castings from kits straight in the bin :cool:
  10. Dan Randall

    Dan Randall Western Thunderer

    Hi Mick

    It was seeing all the replacement parts you were churning out, that made me want a printer of my own! :thumbs:


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  11. mickoo

    mickoo Western Thunderer

    Good cricket, it is the future.

    The trick now is to recognise the supplied part is :shit: before you try and salvage it and clean it up for use, there by saving you hours of wasted energy and blue language :p
  12. mickoo

    mickoo Western Thunderer

    Keep at it and you'll be fine :thumbs:
  13. Ian@StEnochs

    Ian@StEnochs Western Thunderer

    All new techniques for making things go through a period of experimentation when applications are investigated. The new is sometimes an improvement and better, but not always.

    I remember when whitemetal was the bees knees and virtually everything was cast. Whitemetal coupling rods anyone?

    Etching sorted some of the problems but brought in others. Fold up axleboxes?

    If you had invested in one manufacturing process it made sense to use it as much as possible even when it really wasn’t ideal. However what we are getting now, in the better kits anyway, is getting close to ideal. A mixture of etch, cast metal and resin details, injection moulded parts and turned components, but at a price.

    If you are a scratch builder, or use kits as a starting point, then use whatever skills you have and adopt new technology where you can but don’t forget new is always best!

    On my last build, the Baltic tank, I made everything, except wheels and drivetrain, from scratch. I made patterns for the springs and buffers and cast them because there was nothing on the market suitable. The platework I cut by hand, etching would have taken ages and cost quite a lot, the boiler mountings I turned and milled. If I had the skill and 3D printer I would have used them to make the springs, making them by hand did take quite a lot of time and patience

    For my next project I need wheels which are not available from the trade so I have joined the same group as Rob to learn Fusion 360 and perhaps get a printer. Just another tool to add to the armoury!

  14. mickoo

    mickoo Western Thunderer

    You're absolutely right, 3D printing has it's place, as does etching, casting and all the other mediums. Used in the right context it's a big improvement, but it has it's limitations, for some a fear of the new.

    You'll rapidly learn that 3D prints do not solve all of your problems, it can also be costly in resin and more importantly your time, persistent tweaking and adjustment to get the perfect or satisfactory print.

    Going back to plate work, I generally opt for etched if I have to, yes it is expensive (relative) but I factor in time and give it a set rate, I often find that scratch building something time wise is close to, or exceeds the cost of drawing up etches and getting them processed. The recent 72xx was a perfect case, I started out scratch building (because I thought it'd be quicker and easier), but in the end it would of been quicker and significantly cheaper to have made some etches up, such was the extent of the changes required.

    In the end I'm all for mixed media, the hobby needs it, we as train modellers, more so in this scale it appears, seem to suffer poorly with mixed media deficiencies.
  15. Ian@StEnochs

    Ian@StEnochs Western Thunderer

    Good points Mick,

    I prefer cutting my own rather than prepare drawings for etching. For one offs I am not constrained to one thickness of metal but can use what is appropriate for the application. There is also the question of time. When I start a new model I can have most of the major platework cut out in a couple of sessions without having to wait on a third party.

    Getting to grips with a new tool always takes time. Some more than others but usually worth persevering with. I expect to spend a while before mastering the cad package!

    When I did some commercial casting work way back it took a while for me to master the quirks of the process. Some casting sessions I would get every mould producing good castings every spin and others when nothing seemed to work. Eventually I got the hang of things and it became second nature. When I sold on the equipment the buyers gave up on casting and reverted to getting a third party to do it for them.

    Last edited: 26 June 2021
  16. Rob Pulham

    Rob Pulham Western Thunderer

    I am not sure whether it's beginners luck but further sessions today have added a tube under the centre of the flare to help locate the chimney in the smokebox and the rivets around the rim. I still haven't got it completely hollow but I will perhaps try to achieve that on the next one.

    D2 Chimney IV.JPG

    D2 Chimney V.JPG
  17. Rob Pulham

    Rob Pulham Western Thunderer

    The D2 chimney must have been beginners luck. The next one took me two days of fighting to get it finished. Despite the frustrations I have learned much from the experience (I am a great believer that mistakes and things going wrong are far better teachers than when things go swimmingly).

    This chimney is for non condensing C12's and J52's. According to the drawing, the condensing versions were fitted with shorter but otherwise similar profile chimneys. I feel that I have done a better job of this one and it's a bit finer in shape/detail.

    C12-J52 Chimney 1.JPG

    C12-J52 Chimney 2.JPG

    C12-J52 Chimney 3.JPG
  18. Rob Pulham

    Rob Pulham Western Thunderer

    At the risk of boring you, I have continued to play with fusion and next up I drew a dome for the D2.


    Complete with hex nut on the top. Domes are so much easier to draw than chimneys, I did this one in a couple of hours.


    Then I had a go at the GNR version of the Ramsbottom safety valves

    I started out with this


    and then this


    It was at this point that Chris looked over my should and said it looks good but doesn't look right. Of course she was correct in that the spring should be on the lever which I hadn't drawn yet not on the valve columns.

    To be continued...
    michl080, JimG, Ressaldar and 3 others like this.
  19. Rob Pulham

    Rob Pulham Western Thunderer

    This is the final version. it was a bit of a challenge to get all the lever elements constrained so that I could extrude it but I got there in the end.






    By turning different elements off as in the photo I can create separate STL files for just the lever, the complete valves without the cover or complete with the cover.
  20. Ian@StEnochs

    Ian@StEnochs Western Thunderer

    Your doing well Rob. I'm still struggling to draw a simple axlebox!