Am I aiming too high?

[-steves-]

As some of you know, I am currently working on a 3D printed project of an NGG16, not the easiest build and is challenging.

I am "thinking" after that what to do next. First thoughts went to a simple steam engine like a Cracker or similar. However, after looking around I quite fancy a Shay of some description, I am looking at the 70T Shay in particular. Has anyone ever tried to build one of these? Is it aiming too far with an electric 3D printed version? I would have to use bought brass bevel gears to do the power transfer and I am thinking of some form of rubber pipe to do the bits that "bend". I am not sure how well a 3D printed crank would hold up, so that might have to be made in metal, but I think that bit is doable.

I am just after people views on what the issues might be, rather than just a "yeah, go for it" kinda thing. I actually know very little about this type of engine, so input is welcomed. I have found a lovely set of plans on the Shay Plans website which if I undertake this are the ones I would use, though of course they would get changed a bit along the way as I usually do.

[philipy]

Well, I have looked at Shays several times myself but always chickened out, partly because even the small ones are really too big for my line ( or is that just an excuse??). Having said that your mechanical skills and facilities are greater than mine and having seen some of your other work, I think you could do it if you put your mind to it. Actually I suspect that's the crux of the matter though... you'd have to really WANT to do it to get to the mind set of, "where there's a will there's a way".

FWIW, I was going to cheat and have the gears and shafts just going round cosmetically with a much more conventional hidden mech.

[GTB]

If you haven't already found it, this site has photos and data on pretty much any Shay ever built.

https://www.shaylocomotives.com/

70 tonners were mostly class C locos with three trucks running on standard gauge. Big locos even by US standards.

Good luck. At least they used standard bevel gears, so more achievable than building a Climax, where you have to learn gear cutting as well........

Graeme

[Old Man Aaron]

It's the telescoping drive links that throw up a problem to my mind. I don't think rubber hose would work for joints that need to flex as much as a Shay requires. Then again I'm not sure how one might go about it. Maybe with square section brass tube, one inside the other..

[Phil.P]

It's the telescoping drive links that throw up a problem to my mind. I don't think rubber hose would work for joints that need to flex as much as a Shay requires. Then again I'm not sure how one might go about it. Maybe with square section brass tube, one inside the other..

That is how the commercial models do it..

I would also look to the RC vehicle market, for universal joints...

Applying the power, more conventionally, and the rod/cylinders being cosmetic, should make for something more robust IMHO.

Phil.P

[GAP]

What PhilP is suggesting is how Model Die Cast (Roundhouse) went back in the day in HO.
Bit hard to describe but there are pictures of the how to build on this page under Kit 370 Three Truck Shay
https://hoseeker.net/mdcinstructions.html
They used Delrin for the gears and the whole thing was a disaster with numerous complaints about poor running.
I have a book the was written specifically to improve the performance which entailed heaps of work, I did not have the time to get it running correctly so I removed the motor and drives and just ran it a s a dummy double headed with one I own made by Bachmann.
When I went to G scale I bought a 1:20.3 model from Bachmann (in the middle of the GFC when the USD was at parity with the AUD which was the only way I could afford it) and it runs very well.

[-steves-]

I would also look to the RC vehicle market, for universal joints...

Applying the power, more conventionally, and the rod/cylinders being cosmetic, should make for something more robust IMHO.

Phil.P

That's it, perfect. I have a number of RC car universal joints that would do the trick. Thank you so much.

I just knew someone on here would have some better ideas than me.

[Trevor Thompson]

I have also thought about making a Shay.

In fact it was something I thought about making next - to follow on from the three D printed 4420. I was thinking that it would be a appropriate for a 3 D printed live steam model. I have drawn it up in Sketchup - and it is near enough ready to print. It is based on the plan from Colin Binnie's archive. If you are interested you can have the files to play with:

Screenshot 2023-11-12 at 11.15.30.png (429.29 KiB) Viewed 4405 times

As far as flexible joints are concerned it wouldn't be difficult to make the Harley splicer type couplings, and they might even work if resin printed. I was going to try that. Don't forget that each shaft also needs to change its length, I was planning on rod with a wire passed through it and a tube with a slot to slide over that rod. again I think the tube with slot could be printed. Well that is what I thought to try first.

Trevor

[-steves-]

Wow Trevor, that's amazing! I wish I knew how to use Sketchup, then the drawings would be extremely useful to but, but alas, I am a Tinkercad special

I have found this on the net, I think I might be able to construct something similar in Tinkercad and use it as the hex part would be made to slide in and out of one another. Any thoughts on if this would work? Please

The second picture is the same part but without the ends on.

Screenshot 2023-11-13 102733.png (106.5 KiB) Viewed 4360 times

Screenshot 2023-11-13 102252.png (105.02 KiB) Viewed 4360 times

[philipy]

I wish I knew how to use Sketchup, then the drawings would be extremely useful to but, but alas, I am a Tinkercad special

Steve, can Tinkercad import stl's? If so, you could do what I've done with Thornas and if Trevor exports his drawings as stl's, you could then import them into Tinker, save them as Tinker files and work on them from there?

[-steves-]

I wish I knew how to use Sketchup, then the drawings would be extremely useful to but, but alas, I am a Tinkercad special

Steve, can Tinkercad import stl's? If so, you could do what I've done with Thornas and if Trevor exports his drawings as stl's, you could then import them into Tinker, save them as Tinker files and work on them from there?

That is true, with a few caveats. If I import an STL it is fixed, I can not do much with it, scaling is ok, a bit by blocking things out and redoing them, but it is very limited. The other issue is that Tinkercad will only import so many polygons, as it is just a "kids CAD program" after all, if it goes over that limit it won't import it, though that's only typically an issue with figures. If each single component is exported then it makes things much easier to work on when doing an import.

If you can export each part as separate STL's then that would be extremely useful

[philipy]

Thats a shame. If I import stl's into Sketchup, I can work on them as though they were native drawings

If each single component is exported then it makes things much easier to work on when doing an import.

If you can export each part as separate STL's then that would be extremely useful

You'd have to ask Trevor about that I'm afraid. It will depend on how he has drawn it so far and if it is in discrete parts. I always draw separate parts and put them together later, but Trevor may not work that way.

[GAP]

Thats a shame. If I import stl's into Sketchup, I can work on them as though they were native drawings

If each single component is exported then it makes things much easier to work on when doing an import.

If you can export each part as separate STL's then that would be extremely useful

You'd have to ask Trevor about that I'm afraid. It will depend on how he has drawn it so far and if it is in discrete parts. I always draw separate parts and put them together later, but Trevor may not work that way.

The biggest issue I have with Tinkercad is the limitation of not being able to ungroup imported stl's.
I have found a free online version of Sketchup that I am going to explore with the aim of being able to ungroup an imported stl to start with.
If that works I may switch.

[GAP]

I've tried sketchup and am a bit perplexed on how to get a model to view on my screen.
The one I imported appears as a tiny dot on an area that looks like a city block.
Any help on how to make the view smaller would be appreciated.

[philipy]

I've tried sketchup and am a bit perplexed on how to get a model to view on my screen.
The one I imported appears as a tiny dot on an area that looks like a city block.
Any help on how to make the view smaller would be appreciated.

On the toolbar at the top of the screen is an icon that looks like a magnifying glass with 3 arrows pointing out. If you click that, it will enlarge or reduce the entire drawing to fill the screen.
Next to that icon is a magnifying glass which is the zoom control to enlarge or reduce whatever you want within the drawing.
Next to that is a hand, which drags the screen around to get to the bit you want.
Next to that is a red and green circular arrow which allows the view to swivel around 360 degrees, so you can look from behind, underneath, diagonally, etc.

[GAP]

I've tried sketchup and am a bit perplexed on how to get a model to view on my screen.
The one I imported appears as a tiny dot on an area that looks like a city block.
Any help on how to make the view smaller would be appreciated.

On the toolbar at the top of the screen is an icon that looks like a magnifying glass with 3 arrows pointing out. If you click that, it will enlarge or reduce the entire drawing to fill the screen.
Next to that icon is a magnifying glass which is the zoom control to enlarge or reduce whatever you want within the drawing.
Next to that is a hand, which drags the screen around to get to the bit you want.
Next to that is a red and green circular arrow which allows the view to swivel around 360 degrees, so you can look from behind, underneath, diagonally, etc.

Followed the instructions (toolbar is down Left Hand Side in free version) and zoom in the area is still huge. The man in the corner is a bit confusing but if I move the model away from him I can look at what I am doing.
I used "orbit to see a 360 degree view
I did manage to separate a grouped stl that I downloaded using the "explode" function and delete some parts.
Will try to export and print over the coming days when I get some time.

[philipy]

Graeme, I realised after I posted that you are using the current on-line version. I'm still using the 2017 free version on my laptop so there may be some differences to layout and function.

Having said that, I think you can move the location of the sidebar if you wanted to. The 'man in the corner' is extremely annoying, I agree, but if you select him and hit delete he goes away!

I'm not sure if it still applies to the cloud version but in my version there are various optional templates available at the log in screen at the top right corner. I'm using '3D printing - millimetres' so I wonder if you are on some sort of default template at a much larger scale, and/or the other possibility is that the drawing is in mm but the template is feet and inches?

Yes, exploding the stl and then working on it is the way I do it. Be aware though that SU tends to add various extraneous lines when it does the import. They don't affect the drawing as such but they can make it very difficult to see what you are doing. They can deleted manually but it is a very time consuming process.

[Trevor Thompson]

Hi

I also use the free software. "Sketchup Make 2017" is the version I use and it it still to be found on the internet.

To answer can I seperate the components into separate stl files? Yes. I create the drawings as a single file for the whole model, and create each component separately within that file. Each part is saved in the software as a "Component". That stops them being altered when you alter something else. You can also go back and alter each component - and only see the component you are changing while you edit it. Then all the components can be seen as a whole - just like an assembly drawing. That helps to make sure they fit together properly.

I will prepare the stl files and put them in the files section. Just be aware that it isn't quite ready to print - but I will get it ready to share. It might take a couple of days!

Trevor

PS It took me a while to get used to sketchup - but it is really powerful - and it does everything I want it to do. You can move the sidebar, and there is another sidebar which has more functions which you can turn on and off.

[Trevor Thompson]

Some thoughts on using sketchup if you are unfamiliar with it.

In the main menu across the top there is a heading "camera" Use it to change where you see the model from front top back etc.

Start off using the 'top' view and draw things in two dimensions. Boxes circles lines and things like that. Get used to working in 2 dimensions first - then try 3. You can change the view manually to about 45 degrees and "pull" the boxes etc into cubes and the like.


One of the differences between what you see shown on uTube and what we want is working to scale. So two things to help.
Firstly when you draw a box, draw it by drawing the mouse, and then type "20,10" then press return, that makes the box 20mm by 10mm. Same applies to other shapes.

Secondly use guide lines. They are created using the tape measure symbol. Select one of the main coordinates and click on it (they are coloured red blue and green) move the mouse and let go then type 25. You should see a dashed line 25mm from the main coordinate and parallel to it.
So by setting out the guide lines you can just draw the box and let the house button go near the guides and it should snap to the guidelines.

I use guides on the paper drawings I import, so that the guides define the size of say the footplate. It is then easy to keep the model to scale.

Lastly under the heading "window" there is an option "instructor" - way down a long list. click on it to open a side bar which tells you how to use each tool. I still turn it on occasionally when I haven't used sketchup for a while.

Trevor

[Trevor Thompson]

Wow Trevor, that's amazing! I wish I knew how to use Sketchup, then the drawings would be extremely useful to but, but alas, I am a Tinkercad special

I have found this on the net, I think I might be able to construct something similar in Tinkercad and use it as the hex part would be made to slide in and out of one another. Any thoughts on if this would work? Please

The second picture is the same part but without the ends on.


Screenshot 2023-11-13 102733.png


Screenshot 2023-11-13 102252.png

I think that sort of coupling could be made to work. I would prefer a square shaft in that I think the 90 degree angles would be less likely to bind under load than 60 degree angles on hex bar.
I would make the pins in the flexible part from metal. Otherwise just try it! Nothing ventured nothing learnt.

Trevor