Highland Railway Drummond 0-4-4T Passenger Tank

Discussion in 'Kits, Kit bashes & Scratch builds' started by paul_l, Jan 11, 2019.

  1. paul_l

    paul_l Staff Member Administrator

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    Soooooo close

    Now it cured - Andy for resin prints if running your nail over the surface scratches the surface then you need to cure it a bit more. Best done in short exposures so you don't over heat the part which may cause it to crack. After removing the temp strenghtening parts I tried to ream out the 5mm bearing holes, and the reamer is too long :facepalm:.


    .

    It fouls the rear securing plate, so as part of the rear modifications I will lower the top plate to clear the reamer, and print a spacer to bridge the gap (I could add the spacer to the base of the body).

    Also noticed I used a version of the motor mount I used wasn't the one where I'd moved the motor 1.5mm further into the mount. Another job for the todo list.

    In the meantime I will cut away part of the rear plate to allow the reamer to fit in, as I need to confirm that I can install the bearing etc into the motor mount & chassis.

    And I've jus spotted I didn't subtract the worm wheel from the chassis parts so it wo'nt fit in.

    Paul
     
    Last edited: Feb 28, 2021
  2. paul_l

    paul_l Staff Member Administrator

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    Motor position modification, worm gear clearance (Worm Wheel OD = 16.6mm made the clearance 18mm)

    upload_2021-2-28_16-1-9.png

    and mounting plates front and rear position adusted to allow access for the reamer.

    upload_2021-2-28_16-12-27.png

    Next up the sprung pickups

    Paul
     
  3. gormo

    gormo Staff Member Administrator

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    I`d be tempted to try and cut down the reamer Paul if at all possible.......:scratchchin:
    When it comes to the bogie you may need to add a washer top and bottom to that compression spring. They tend to compress better / truer vertically if the top and bottom have a good flat base to make contact with.
    In my experience, bogies / pony trucks can be a source of grief so they need to be set up well. The applied pressure needs to be central to distribute the load evenly on a two axle job, yet on a single axle the pressure needs to be just right to avoid the axle either tracking too much in the straight ahead or basically bouncing off the rails due to lack of pressure.
    I would advise lots of testing over points in both directions. Trailing should be OK but you never know.?
    I have one loco with a two axle bogie at the front that will derail if the wheels get dirty.......there is such light pressure applied that a small bit of gunk will make the wheel bounce off the rail.
    Not a problem once you`ve worked out the solution...........anyway......just do lots of testing.:thumbs:
    :tophat:Gormo
     
  4. Keith M

    Keith M Staff Member Moderator

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    Angle grinder or bench grinder if you have one should cut down the reamer as it'll be hardened steel, then you can grind new flats onto it if needed.
    Keith.
     
  5. paul_l

    paul_l Staff Member Administrator

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    Cheers guys, i'll look into it.

    Quickie this morning - Rear Sand box

    upload_2021-3-1_10-36-16.png

    Mirrored to give both sides

    upload_2021-3-1_10-37-0.png

    Just need to add to the chassis.

    Paul
     
  6. paul_l

    paul_l Staff Member Administrator

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    And on the chassis

    upload_2021-3-1_11-3-48.png

    There is a hole in the base to allow a 0.9 wire to be inserted to act as the sander.

    Dog walking time - he gets more out time than I get :avatar:

    Paul
     
  7. paul_l

    paul_l Staff Member Administrator

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    Bearings arrived today, but still waiting for the 3/8 ths reamer.

    The gears were reamed 3/4 of the way with the 2mm reamer, and the remaining 1/4 pushed on with a clamp / vice. Not overly worried as this is a test gear box and I can print more gears.

    The 2mm ID bearings are a sliding fit in to the 5mm reamed holes, and will be secured with loctite on the final builds (still in transit).






    I will connect up the motor and give the first stage of the gear box a run in. I can fit the worm, but not the wheel as I can't fit the axle bearings.

    Paul
     
  8. gormo

    gormo Staff Member Administrator

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    Lookin` good Paul.....:thumbs:
    If you`re looking for a safe lubricant for those gears, Gary put me onto something a few years ago that was passed onto him from another modeller.
    KY Jelly
    https://www.pharmacyonline.com.au/k...term=4579122335781193&utm_content=Ad group #1
    I have tried it on a couple of locos and I`m not 100% convinced of it`s ability on a really noisy gear train, however it is a lubricant that will not affect your resin, as it`s water based and safe for use in delicate areas on humans.
    It could possibly just add that extra smoothness on a nice set of gears like the ones you have made.
    :scratchchin:
    :tophat:Gormo
     
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  9. paul_l

    paul_l Staff Member Administrator

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    Think I'll send Morag out to buy in KY jelly, if I buy it I may need a lawyer :avatar:.

    I can just imagine the comments - While grinding I was really noisey, just a small application of KY jelly and it's so smoooooth :avatar:

    After looking at the last photo


    Looks like Ineed to cure the gears a bit longer, the large gear scratched with my thumb nail.

    Still need to connect the motor to a power supply.

    Paul
     
  10. paul_l

    paul_l Staff Member Administrator

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    I connected up the power this morning and all went reasonably well.

    The issue I did have was the bearings would move as they are only placed in position -on the final chassis / gearbox I will glue them in position with loctite (when it arrives). I will also need to fit some teflon spacers on the worm shaft, between the large front gear and the bearing, and either side of the worm gear between the bearings. The Teflon is 4-2 teflon tube trimmed to length (I have a reasonable amount from my 3D Filament printer - it's used to guide the filament into the hotend).

    There is a bit of vibration felt in the gearbox, so may try adding a little cream cleaner to help polish the teeth, before trying a lubricant.

    Paul
     
  11. Bazzmund

    Bazzmund Full Member

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    At some point I really need to look into 3D printing for my stuff
     
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  12. paul_l

    paul_l Staff Member Administrator

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    It's becomming harder to ignore all the time.

    I have to look into some of the engineering / prototyping grade resins, supposed to be harder wearing and support finer detail, but are 4 to 8 times the cost of my current resins. For companies the cost is recoverable, and if I only had to make one print then maybe justifyable (the resins I've seen so far range from £100 to £250 for 500ml / 500g bottle), I have used well over 1 litre of resin so far on this build (approx £45 worth of resin), but have been learning so silly mistakes have been made, plus a couple of re-thinks and a lot of playing.

    From this one model, I have worked out how to make Chimneys, Domes etc etc, and now gears & gearboxes, and I have no CAD or 3D modelling experience or training, so have to assume I'm doing a lot of this wrong or at least very inefficiently. I did take the body into my old work for a visit last week, and showed my efforts to the head of the projects team / drawing office, and was impressed by the standard that the 3D printers are capable of.

    The only downside is I'm enjoying it too much, and it's stopped all progress on Nellie, the 6 wheel full brake, the 4F, and 5 other loco kits all ahead of this loco in the que :whatever:.

    I see the big benefit comming when I start on the wagon stock, £8 - 10 for a set of wheels and a few pound for the resin, I could easily rattle off a couple of wagons a day and can easily justfy multiples of each type, a little harder with a locomotive when there was only 4 ever built.

    Paul
     
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  13. Bazzmund

    Bazzmund Full Member

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    I can see the benefit to it. With where I live and the period I model it's hard to ignore the possibility of batch building a pit to port train in days rather than weeks.
     
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  14. paul_l

    paul_l Staff Member Administrator

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    Well the main chassis is on a break at the moment untill the reamer arrives, and I've started on the bogie.

    The Slaters 2'6" 8 spoke wheels use a 1/8th inch axle, I will support these with Hobby Holidays 1/8th Axle bushes.

    I've drawn these up in 123D

    upload_2021-3-4_14-23-37.png

    My intension is to have two side frames - pivoted to give some compensation, with a central block that will provide a degree of side sprung side play, pivot points and height adjustment - hey it might work.

    Starting with the side frame

    upload_2021-3-4_14-36-14.png

    A total of 8 bushes - 2 per axle per frame will be used.

    The frame will be connected to the central block using an M2 cap screw through a 2mm ID 5mm OD x 2.5 mm bearing (this providing the pivot) all hidden by a representation of the leaf springs.

    upload_2021-3-4_14-44-20.png

    Back to virtual drawing board then

    Paul
     
  15. paul_l

    paul_l Staff Member Administrator

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    A very blocky version to start with

    Inner side showing the bearing and pivot

    upload_2021-3-4_15-9-25.png

    and the outer side

    upload_2021-3-4_15-12-25.png

    The bearing will be glued into the side frame, as mentioned earlier the side frame is secured an M2 cap screw (where the pivot is).

    Now to start creating some of the basic shapes.

    I also have an idea for the pickups - home made sprung pickups using Markits extra long handrail knobs as the plunger through a hole in the side frame for each wheel. A piece of brass wire inserted through the handrail knob holes and secured in the center of the bogie provides the spring and electrical connection. The hand rail knob shank being trimmed to length to give enough tension to keep the pin in contact with the back of the wheel.

    upload_2021-3-4_15-27-50.png

    Paul
     
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  16. Keith M

    Keith M Staff Member Moderator

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    Hope you can find a retailer with some of those extra long handrail knobs Paul, if you have to order direct from Markits, you could be in for a fair wait, think he also has a minimum order value now too. How about brass split pins soldered up solid???
    Keith.
     
  17. paul_l

    paul_l Staff Member Administrator

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    I'm ahead of you Keith - on order today from Roxey Mouldings - they stock a lot of Markits stuff.

    Split pins may work, suppose it would depend on how round the pin part would be, so as to freely move within the hole and not bind.

    Paul
     
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  18. Keith M

    Keith M Staff Member Moderator

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    Jim Mcgeown (Connoisseur) supplies copper split pins in some of his kits for use as handrail knobs and pipe clips and they work fine for those jobs. I'll be interested in seeing if your idea works as plunger pickups are not always the most suitable in some cases and phosphor bronze wire 'wipers' often need more space for PCB pads to solder them to. A new way of looking at the problem with a bit of thinking outside the box is often worthwhile, so hope it's a success.:thumbup:
    Keith.
     
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  19. paul_l

    paul_l Staff Member Administrator

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    A bit more progress

    Bogie sides

    upload_2021-3-5_21-28-35.png

    holes in the leaf springs are for the plungers.

    Just to do the center piece.

    Paul
     
  20. paul_l

    paul_l Staff Member Administrator

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    forgot I have the mud gaurds for the wheels to do as well, these will need to be optional, as I've seen photos of both axles, single axle or none fitted at all.

    They will be attached to blocks above the axle via a screw.

    Paul
     
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