Home made Gearbox

Discussion in 'Computer Aided Modelling' started by paul_l, Feb 23, 2020.

  1. paul_l

    paul_l Staff Member Administrator

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    "Just buy one" I would expect to everyones first comments, but bear with me there is method to my madness - I hope.

    I am learning CAD, I'm ok with a pencil and paper, but the CAD stuff is all new, as an apprentice and even at School we had Drawing boards set sqaures and even a variable one we could borrow, with the teacher always zeroing the value so no one could gain an advantage.

    However, back to the story, I wanted to learn to use CAD, on my old PC, I have Draftsight 2016 installed, but alsa not on my new PC, also as part of the redundancy packages an introductory class into Solid Edge 2D was offered, so I jumped at the chance. Completed the course, then didn't look at it for another 3 months :facepalm:

    Now, downloading the software (a free cut down version is available - which is the one I use, think I'm working on becomming an honoury Scotsman / Yorkshireman), opening up the screen I have a blank sheet of er screen

    upload_2020-2-23_16-13-21.png

    Ok what am I going to draw....... :scratchchin:

    After another while - I'm taking procrastination to another level, possible PHD, but i'll have to think about that .....

    I know I'll design the chassis for the Highland Railway Passenger Tank, I learnt a lot from that attempt, and will be back on a screen soon (I hope), but was a bit too complicated as a first attempt, especially as I was going to make a fold up chassis.
    More "research" was carried out, and decided to have a go at making my own motor mount, using Markits O gauge 20:1 gears, and O gauge 3/16th axle bushes, plus a Mashima style motor from Taffvale models

    Now I also fancied etching this myself (in for a penny .....), more video watching :whatever:

    First the maths to establish the axle center lines

    Dia of worm 6.1mm, dia of worm wheel 11.3, which added together gives 17.4mm giving a center of 8.7 mm, however when meshed the overall measurment is 16.8 mm, the difference 0.6mm was subtracted from the theo cetnter to give the gear center of 8.1mm.

    Next up the off set between the motor front and wheel axle.

    I measured from the front of the motor to the middle of the worm = 10mm, as I wanted to use 20 thou material, I made the distance 9.5 mm.

    The pitch between the motor securing screws is 11.8 mm ( see Taff Vale Models Motor Spec sheets I've used the bottom one 1833 motor)

    Final measurement - and this is the suck and see bit for me I'm aiming for approx 16 mm between the inner side of the frames to give me room to center the worm wheel to the worm, so to allow the metal to be bent I have made the center 8.4mm and will have a line 0.4 mm wide half etched in for the fold, the final dims will be a lesson learned for the next project.

    Creating a new drawing, then a new layer for alignment (I learned this lesson from the first attempt on the chassis :whatever:)

    upload_2020-2-23_17-5-27.png

    Then on a new layer I created the outline, and added some alignment marks and a border

    upload_2020-2-23_17-6-52.png

    A mirror line was added, and a mirror image created, and half etch lines.

    upload_2020-2-23_17-11-11.png

    This then printed on to acetate film - to be honest, before commiting to acetate multiple copies was printed to paper.

    Another lesson for the future is to have the alignment cross hairs a easy to measure distances (i.e. multiples of 10mm) in both directions, as the printers can have a mind of thier own, and rescale images all over the place.

    So I now have an acetate ready to make a pocket to slip the metal coated in photo resist for the exposure process, but that will be in the next post, as I've got the bit on order.

    Paul
     
  2. Toto

    Toto I'm best ignored Staff Member Founder Administrator

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    Carry on Sir. Well done ..... another new skill.
     
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  3. York Paul

    York Paul Staff Member Moderator

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    We all know what this means ... :avatar::avatar::avatar:
     
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  4. Keith M

    Keith M Staff Member Moderator

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    Yes, more work!!!:avatar:
    Keith.
     
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  5. York Paul

    York Paul Staff Member Moderator

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    :avatar::avatar::avatar: yes and all those enquiries of possible "can you just design me" ideas for Scottish engines yet to come.
     
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  6. paul_l

    paul_l Staff Member Administrator

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    Actually, I was thinking of a quick solution for Leek Station awnings.

    As quick simple fix for smoke box number plates looks very doable as well, but yes my main intension is to make the underframes for a Highland Railway 0-4-4T Passenger tank, the 0-6-0 Barney and the 4-4-0 Small Ben, after that we'll see.

    As mentioned above, I have a few bits on order

    Photo Resist Film - my original order was placed with ebay just before the Chinese New Year - and with everything else they have being having to deal with a 5M roll of Photo resist, so on Friday I decided to order a roll from Amazon via prime, and yes you've guessed both arrived on Saturday morning. Not a problem as that gives me plenty of film to play with.

    The developer is Sodium Carbonate often sold as Soda Ash, the bag I have will last a while.

    The Etchant I am going to use is Ferric Chloride, I could use a mix of Hydrogen Peroxide and Hydrochloric acid, but this is pretty corosive, very fast acting and produces a lot of fumes. The Ferrick Chloride, still corosive, but a slower more controlled process, we'll see about the fumes later when I try it.

    Final bath to remove the cured photo resist is Sodium Hydroxide (Caustic Soda).

    The photo resist cure under UV light - daylight will work so care must be taken in handling the filw and keep the exposure to daylight to a minimum.
    One of the advantages I have with doing the resin 3D prints is I have a UV light source (a finger nail polish curer).

    For small items I will be able to use ex-food containers - another good excuse for a curry, I have also got on order some 5x7 photographic development trays, very handy as these are also designed to work with both acids and alkali's. I have some larger 10x8, 12x10 & 20x16 trays in the loft from when I used to do B&W processing.

    Last item on order are a set of photographic tongs (all plastic) as any item made from metal will not do well in the Etchant.

    Once everthing is here I will post the next installment.

    Paul
     
  7. Andy_Sollis

    Andy_Sollis Full Member

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    I’m beginning to know that feeling each time Yorkie has a new NSR project.

    Like a fish to the hook and bait :facepalm::avatar:
     
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  8. York Paul

    York Paul Staff Member Moderator

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    Honest guv promise there will never be any more after this one.:avatar:
     
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  9. York Paul

    York Paul Staff Member Moderator

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    Is photo etching the awnings something that could be done Paul ?:thumbup: heck I'm starting to sound a bit like Toto now.
     
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  10. Andy_Sollis

    Andy_Sollis Full Member

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    :facepalm::facepalm::facepalm::facepalm::faint:
     
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  11. paul_l

    paul_l Staff Member Administrator

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    This is worrying on so many levels.

    Back to the question, can't see why not, just needs the drawing done. Then we get to play with chemicals etc etc.

    Paul
     
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  12. York Paul

    York Paul Staff Member Moderator

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    Should I pm you the spec for the feather cuts... they are really straight forward ... nowt fancy
     
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  13. paul_l

    paul_l Staff Member Administrator

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    go for it - I need to learn the software, and a real example is always better than an example

    \paul
     
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  14. York Paul

    York Paul Staff Member Moderator

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    I can tell you from the NSR estate plans I have the width of these feather boards forming the canopy valence is six inches wide, however no measurements are given for the decor cuts but I'd say the shorter ones are 4 inches less in length and the holes seem to be around 8 or 9 inches above the bottom line of the longer boards... holes about an inch diameter and corners cut at one and a half inches at 45 degrees. I think the picture was taken by the late John Burgess in the early 1960's. I'll check the 1895 estate plan to see what the girder size was they used on the canopy... I think it was 10" x 5" beams... this will give us the feather board length.

    cheers Yorkie



    [​IMG]
     
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  15. paul_l

    paul_l Staff Member Administrator

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    Sure they are round hole and not square diamonds ?

    The support brackest look interesting as well

    3ft looks about right for the long board length.

    Paul
     
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  16. York Paul

    York Paul Staff Member Moderator

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    I thought so too, if you take 18 inches from the bottom to the decor strip in the middle which hides the nailing into the canopy beams then there's another 18 inches of distance to the capping board at the top.

    Do you want to have a go at the support bracket too? It has a little star set into the circle...I'll measure the bracket size from the estate plan I have.
     

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