Dabbling in Fusion 360

Discussion in '3D Modeling Projects' started by Rob Pulham, Jun 25, 2021.

  1. Rob Pulham

    Rob Pulham Happily making models Staff Member Administrator Feature Contributor

    Messages:
    3,069
    Likes Received:
    3,021
    Joined:
    Sep 15, 2017
    A good drawing helps but I do agree with you. It's very easy to forget just how small these things will be at 7mm when you can zoom in and out at will. For example there should have been some slots in the screws on top of the oil pot on the clamping piece but I reasoned that they would neither print nor cast at that size so left them off.

    Don't be too hard on yourself with your own efforts. Bear in mind that I am only learning to draw, whereas you are learning to print too. From where I am sat printing requires as much if not more skill than the actual drawing does.
     
    paul_l and Andy_Sollis like this.
  2. Andy_Sollis

    Andy_Sollis Staff Member Moderator

    Messages:
    2,913
    Likes Received:
    2,824
    Joined:
    Aug 4, 2018
    Its an interesting point.
    There are times you go to town on the detail only to find it’s too small to see/paint or even print ! There is also the fragility of the medium. Brass is ok, but the resin may be a little brittle at times.

    that said, when I decided to do the block instruments for Leek signal box some parts were only .2mm high… yet come to print it’s nearly all visible.. however, I think it will be a photo that represents the display rather than try and paint.. unless there are any willing volunteers? :scratchchin:
     
    paul_l likes this.
  3. paul_l

    paul_l Staff Member Administrator

    Messages:
    8,802
    Likes Received:
    4,765
    Joined:
    Dec 5, 2015
    I would also add that I've found holes start to disapear if they are smaller than 0.8mm in diameter, at 0.6 to 0.7 mm dia. you will see a dimple, which will easily drill out with a pin vice.

    Paul
     
    Andy_Sollis and Rob Pulham like this.
  4. Rob Pulham

    Rob Pulham Happily making models Staff Member Administrator Feature Contributor

    Messages:
    3,069
    Likes Received:
    3,021
    Joined:
    Sep 15, 2017
    I recently drew up a few NER boiler fittings for my friend and fellow Platform 1 member Kerry

    1fa13307-90b2-4486-9697-9b9c8290b338.PNG NER_Wordsell_(Wilson)_Chimney_Chimney_2021-Aug-26_06-25-25PM-000_CustomizedView33107974752.png NER_Wordsell_(Wilson)_Chimney_Chimney_2021-Aug-26_06-16-11PM-000_CustomizedView13953069266.png

    NER_Ramsbottom_Safety_Valve_Trumpet Polished Brass 2.png

    NER_Ramsbottom_Safety_Valve_Trumpet Polished Brass 3.png

    NER_Ramsbottom_Safety_Valve_Trumpet Polished Brass.png

    I have also drawn a dome but I want to improve the transition between dome and flare so I plan to have another go.
     
    jakesdad13 and Andy_Sollis like this.
  5. Andy_Sollis

    Andy_Sollis Staff Member Moderator

    Messages:
    2,913
    Likes Received:
    2,824
    Joined:
    Aug 4, 2018
    I’m envious Rob! That’s some good modelling!
    Not sure if you saw my FB messenger but I’m up and running again from this AM and your parts have printed (well it was still printing when I left for work) Will check at 2am when I’m back home.
    Andy
     
    Rob Pulham likes this.
  6. Rob Pulham

    Rob Pulham Happily making models Staff Member Administrator Feature Contributor

    Messages:
    3,069
    Likes Received:
    3,021
    Joined:
    Sep 15, 2017
    Thanks Andy,
    No I hadn't seen it, I don't really visit Facebook much lately. I find I spend far too much time looking at utter crap without really meaning to.
     
    Andy_Sollis likes this.
  7. Rob Pulham

    Rob Pulham Happily making models Staff Member Administrator Feature Contributor

    Messages:
    3,069
    Likes Received:
    3,021
    Joined:
    Sep 15, 2017
    I managed to improve the dome, it's still not as good as I might like but it's the best I can do for now with the skills that I have.

    NER J Class Dome MKII -2.png NER J Class Dome MKII -3.png NER J Class Dome MKII.png
     
    Andy_Sollis and jakesdad13 like this.
  8. Tom Burnham

    Tom Burnham Full Member

    Messages:
    19
    Likes Received:
    28
    Joined:
    Oct 18, 2020
    Hi Rob,

    I see that, like many before you, it has been incorrectly assumed that the NER safety valve cover is round whereas its shape is rather more complex than that. By way of illustration I've attached some photos taken at the Head of Steam Museum in Darlington of a surviving example, together with a dimensioned side elevation drawing. As you can see, the opening at the top is oval in shape and the cover has been entirely fabricated from brass sheet. I think the chimney and dome could do with some further work as to my eyes the chimney looks too squat and the dome should have tapered sides whereas they look to be parallel. Did you work from the drawings of the compound and rebuilt versions contained in Ken Hoole's book? If you don't have these I can send you some scans if it would help.

    Tom.


    RIMG0020_edited-2.jpg RIMG0018_edited-2.jpg RIMG0019_edited-2.jpg NER Safety Valve Cover.jpg
     
    jakesdad13 and Andy_Sollis like this.
  9. Rob Pulham

    Rob Pulham Happily making models Staff Member Administrator Feature Contributor

    Messages:
    3,069
    Likes Received:
    3,021
    Joined:
    Sep 15, 2017
    Hi Tom,

    I did wonder if the safety valve cover should be oval at the top but when looking at photos that I had taken of the Class M at Shildon it looked round.
    I do have the Hoole loco book but used some drawings by Roche that Kerry supplied for the dimensions.
    When I have a bit more time I shall revisit them.

    Thanks for pointing me in the right direction.
     
    Andy_Sollis likes this.
  10. Rob Pulham

    Rob Pulham Happily making models Staff Member Administrator Feature Contributor

    Messages:
    3,069
    Likes Received:
    3,021
    Joined:
    Sep 15, 2017
    Hi Tom,

    Just looking at the drawing that you have kindly included, one key dimension that's missing is the width of the oval across the narrow section. It was a lack of this dimension on the Roche drawing that pushed me to make it round.

    Thanks again.
     
    Andy_Sollis likes this.
  11. Rob Pulham

    Rob Pulham Happily making models Staff Member Administrator Feature Contributor

    Messages:
    3,069
    Likes Received:
    3,021
    Joined:
    Sep 15, 2017
    Hi Tom.

    Just for comparison purposes, this is a snip from the Roche drawing showing the safety valve bonnet.

    There is quite a difference in sizes compared to the drawing that you posted.

    Roche NER Safety Valve Trumpet drawing.jpg

    I had already scanned the Class J GA drawing in the Hoole book but there aren't many legible dimensions so I will have to look a bit closer to see if I can find something to scale from for the chimney and dome. I see that you mean about the sloping sides of the dome. That will make it even easier to transition from the dome to the flare.
     
  12. Tom Burnham

    Tom Burnham Full Member

    Messages:
    19
    Likes Received:
    28
    Joined:
    Oct 18, 2020
    Hi Rob,

    Most of the commercially produced castings for the NER Ramsbottom safety valve cover are incorrect in one way or another. The best example I've seen was that produced by Walter Hodgson for his Piercy Model Products NER Class E1/J72, now with DJH who will not normally supply castings separately.
    I think the Head of Steam's example is of the taller version shown here -

    Tall NER Safety Valve Cover.jpg

    and it looks like the Roche drawing is based on this. It wasn't used on the Class J.

    My scan of the GA drawing of the rebuilt Class J taken from the Engineering magazine has a linear scale at the bottom that can be used to determine measurements.

    Tom.
     
    Rob Pulham likes this.
  13. Rob Pulham

    Rob Pulham Happily making models Staff Member Administrator Feature Contributor

    Messages:
    3,069
    Likes Received:
    3,021
    Joined:
    Sep 15, 2017
    Thanks Tom,

    If I can find the depth across the narrow part of the oval it shouldn't be too difficult to draw up a correct version.
     
  14. Tom Burnham

    Tom Burnham Full Member

    Messages:
    19
    Likes Received:
    28
    Joined:
    Oct 18, 2020
    Rob,

    The width of the curved rim at the top can be calculated from the dimensions shown on the drawing as 2". If you enlarge the narrow side view photo (RIMG0018_edited-2) on the screen so that the rim measures 2" and then measure the width across the lip I get 8.75" or just over half of its length. Does that sound about right?

    Tom.
     
    Rob Pulham likes this.
  15. Tom Burnham

    Tom Burnham Full Member

    Messages:
    19
    Likes Received:
    28
    Joined:
    Oct 18, 2020
    Hi Rob,

    Having calculated the dimensions of the chimney from the GA published in the Engineer it would appear that it is based on a design used in several other classes as shown in the attached drawing. The only difference is in the height which is 2' 7".

    Tom.

    NER Chimney.jpg




     
    Rob Pulham likes this.
  16. Rob Pulham

    Rob Pulham Happily making models Staff Member Administrator Feature Contributor

    Messages:
    3,069
    Likes Received:
    3,021
    Joined:
    Sep 15, 2017
    Thanks again Tom,
    I used a similar but slightly more long winded method to get to the same result.

    in between a rather busy day, I managed to redraw the safety valve bonnet.

    Safety Valve Bonnet 1.png Safety Valve Bonnet 2.png Safety Valve Bonnet 3.png

    Safety Valve Bonnet 4.png Safety Valve Bonnet 5.png Safety Valve Bonnet.png

    I was that pleased with the result that I got a bit carried away with the rendered images....
    Next up is the chimney
     
    Last edited: Aug 31, 2021
    paul_l, Andy_Sollis and Mossy like this.
  17. Mossy

    Mossy A classic grump Yorkshire man Full Member

    Messages:
    586
    Likes Received:
    784
    Joined:
    Sep 8, 2020
    That looks superb Rob.
     
    Rob Pulham likes this.
  18. Rob Pulham

    Rob Pulham Happily making models Staff Member Administrator Feature Contributor

    Messages:
    3,069
    Likes Received:
    3,021
    Joined:
    Sep 15, 2017
    Thanks Tom, I will be tackling the chimney next.
     
  19. Tom Burnham

    Tom Burnham Full Member

    Messages:
    19
    Likes Received:
    28
    Joined:
    Oct 18, 2020
    Rob,

    Did you want us to spot the deliberate mistake?
    You've rotated the top by 90°. The narrow part should be inline with the boiler.
    Could you narrow the width of the lip so it looks more like sheet brass? I know there are practical limitations as to how narrow you can go but it would be nice to see it looking more like the original.

    Tom.
     
    Last edited: Sep 1, 2021
    Andy_Sollis likes this.
  20. Rob Pulham

    Rob Pulham Happily making models Staff Member Administrator Feature Contributor

    Messages:
    3,069
    Likes Received:
    3,021
    Joined:
    Sep 15, 2017
    Oh bleep!,
    I think I need to lay down in a darkened room.

    Believe it or not the rim is only 0.6mm thick but I will see if I can make it look better.
     
    jakesdad13, paul_l and Andy_Sollis like this.

Share This Page