Austro Daimler Build project - VIDEO

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Re: Austro Daimler Build project - VIDEO

Post by philipy » Mon Oct 24, 2022 1:47 pm

OK, as promised, herewith the video of this sardine can in operation. :lol:




Early on in Andrew's original thread, long before I had any thoughts of actually building it, tongue in cheek I said that making the roof go up and down would be an R/c challenge. So, when I actually started the project I thought I'd better put my money where my mouth is, and then Rik made a comment that it would also need a telescopic driver....
Philip

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Re: Austro Daimler Build project - VIDEO

Post by Peter Butler » Mon Oct 24, 2022 2:04 pm

That is so clever Philip, looks a treat too! Can't wait for your next challenge, you make them look too easy.
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Re: Austro Daimler Build project - VIDEO

Post by ge_rik » Mon Oct 24, 2022 2:56 pm

I didn't realise you'd also motorised the roof (and driver).
That is impressive!

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Re: Austro Daimler Build project - VIDEO

Post by SimonWood » Mon Oct 24, 2022 3:54 pm

Brilliant!

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Re: Austro Daimler Build project - VIDEO

Post by philipy » Mon Oct 24, 2022 6:21 pm

Thanks guys.

Rik, this why I was talking to you about using the Tx22 inertia knob to control a continuous servo. That's what drives the roof up and down and also, via a linkage, bends the driver in half at the waist and then straightens him again. It caused my last remaining brain cell much damage working it all out!!!It also explains why a very simple model took over two months to build. :lol: :roll:
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Re: Austro Daimler Build project - VIDEO

Post by Phil.P » Mon Oct 24, 2022 6:57 pm

Excellent result!
:thumbleft: :thumbright: :ugeek

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Re: Austro Daimler Build project - VIDEO

Post by Garethep » Mon Oct 24, 2022 7:06 pm

Fantastic and very clever!

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Re: Austro Daimler Build project - VIDEO

Post by ge_rik » Mon Oct 24, 2022 7:20 pm

philipy wrote: Mon Oct 24, 2022 6:21 pm Thanks guys.

Rik, this why I was talking to you about using the Tx22 inertia knob to control a continuous servo. That's what drives the roof up and down and also, via a linkage, bends the driver in half at the waist and then straightens him again. It caused my last remaining brain cell much damage working it all out!!!It also explains why a very simple model took over two months to build. :lol: :roll:
:thumbright: :thumbright:

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Re: Austro Daimler Build project - VIDEO

Post by Andrew » Tue Oct 25, 2022 8:23 am

Absolutely fantastic!

All the more so when you consider that the whole thing's barely any bigger than the skips it's pulling...

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Re: Austro Daimler Build project - VIDEO

Post by Trevor Thompson » Tue Oct 25, 2022 6:47 pm

That is most very satisfying!

Brilliant no less.

I would love to see more detail on the mechanisms involved.

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Re: Austro Daimler Build project - VIDEO

Post by philipy » Tue Oct 25, 2022 9:55 pm

Trevor Thompson wrote: Tue Oct 25, 2022 6:47 pm
I would love to see more detail on the mechanisms involved.
Thanks for the kind words, Trevor.
I'll do my best with an explanation, but I'm afraid I didn't take nearly as many pics as I intended.

To begin with I couldn't see any way to power the four spindley support rods to lift it, but then I spotted on one of the drawings that there is clearly what I assume is an exhaust pipe that sticks up the through the roof, roughly in the centre. So if I could power that, it would give me a good chance of a reasonably balanced lifting point.
Some experimenting showed that a length of M2 threaded rod, running in a 2.5mm ID brass tube with a nut soldered to the bottom, would give a Lead Screw effect. All it then needed was the next size bigger tube to cover the bottom section when extended.
To power it I used an SG90 Continuous Rotation servo mounted upside down, with a plastic gear mounted on the servo shaft. This gear then drives another gear mounted on the bottom of the M2 threaded rod. This was then all mounted to a brass bracket superglued to the side of the servo.
Screenshot 2022-10-25 21.21.39.png
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The original plan was to hide the servo inside the 3D printed engine but I had to fudge it because the servo was too big to actually be concealed. The engine is resin printed and I used the Chitubox 'Hollowing' function to leave 1.5mm thick walls, then used a Dremel to remove the bottom skin and razor-sawed it in half horizontally. I had to file the fixing lugs slightly on the servo to get it to go inside the bottom half of the engine and then carefully open out the top to allow it to go up all the way and then I packed it with Milliput so that I would have something to screw the servo to. Next I offered up the top section and cut that to fit on top and when I was happy, glued it on. Finally I drilled a hole to allow the "exhaust pipe" to stick up through.

This picture shows it from the top - the black tube is the bottom shroud tube of the exhaust/lifting mech. The servo body is the angled lump next to it.
P1010004.JPG
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As I said, it's a continuous rotation servo which has a PWM null point at 1.5ms, so above that it rotates one way and below that it goes the other. I discovered, thanks to Rik, that it is possible to reprogram the "Inertia" knob of a Deltang type Tx22 so that it emits a PWM signal on Ch4, which is exactly what the servo needs - turn the Inertia knob and the servo rotates one way and keeps going until it is stopped by centering the knob, then going the other way the rotation reverses. Since the tube is fixed to the roof, the nut climbs up the threaded rod as it rotates and the tube which is fixed to the roof pushes it up...simples! :D

I'll try to explain the driver folding mechanism tomorrow, since it is linked to the roof supports.
Philip

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Re: Austro Daimler Build project - VIDEO

Post by ge_rik » Wed Oct 26, 2022 8:52 am

Ingenious!!!

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Re: Austro Daimler Build project - VIDEO

Post by philipy » Wed Oct 26, 2022 9:32 am

The prototype's roof has 4 vertical support poles placed symetrically and these would need to counteract the turning moment of the lifting mechanism. So they would need to be constrained at both their tops and their bottoms, yet still be free to move up and down without imposing too much mechanical resistance. To achieve this I designed and printed a roof support frame which fitted the inside curve of the roof and with grooves running down each corner to take a piece of 0.8mm dia brass rod. The roof was fixed to this temporarily and the whole contraption positioned, then when I was happy, the four bottom corners were glued to the sides of the body, approx 5mm below the top edge. This ensured that I would have 4 perfectly vertical rods in due course.
Screenshot 2022-10-26 06.40.48.png
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The roof was removed from the frame and 4 lengths of brass rod cut. 2mm at one end of each was bent to an angle matching the roof curve, to sit in a small groove in the top face of the frame. Fortunately, at this point I realised a potential problem, which I'll come back to, but as a result I glued only three of the legs in place and omitted the one behind where the driver would be. Next he roof was glued to the frame and the frame was then carefully cut free of the 4 bottom corners, leaving them glued to the body. Finally the 4 legs of the frame were cut free from the roof, leaving the 3 support rods hanging down. Offering it up the body and inserting the rods into the fixed bottom 'bearings', I checked that the roof slid up and down quite freely.

Now came the bit I was very uncertain about, the driver needed to be able to move out of the way as the roof came down and given the open and cramped interior there was no real way of hiding a mechanism, but I did have a vertical rod behind the driver if I could somehow use that.
The driver was resin printed to sit on the stool, the dimensions of which I got from one of the drawings. I worked out that by slicing him in half diagonally from his waist to his bum and putting a hinge in his groin, he would just clear the lowered roof if folded forward, so all I had to do was work out how the rod coming down could tip him forward and then straighten him as it went back up.
The vertical rod movement is approx 29mm but from sitting to leaning forward the body vertical movement is only about 15mm so the body needed to be pushed up by a rod coming down twice as far! Physical space, physics and the laws of mechanics were not my friends at this point. :(
Somehow the idea of a Bowden cable wormed its way into my brain cell, followed by a bit of lever mechanics. To cut a long story short, I fixed a short length of brass tube to the bottom of the roof dropper that was still not fixed and to this I soldered a short piece of rod at right angles. I had to draw and resin print a restraint to force it to move vertically, this was basically a flat backed tube with a slot down the front face to allow the pin to travel up and down.
Next I fashioned a lever from a piece of 4mm scale bull-head rail. This had a hole at one end to fit over the dropper pin and near the other end I drilled/filed a slot to be a sliding fit on a 14BA screw.
This was all mounted on a piece of 12thou brass, cut and bent to exactly fit on the floor/internal wall of the loco at the drivers position and would allow me to work on it with having to be concerned about the rest of the model.
By coincidence the vertical tube was exactly behind the centre of the driver, so to get a push up as the rod came down I needed to reverse the direction and also reduce the travel by approx 50%. Going back to the Bowden cable idea, I resin printed a U-shaped tube with 1mm dia ID and then put a length of monofilament nylon fishing line through it, this is 0.55mm dia and slides easily. The lever had a hole drilled in it, to again take a 14BA screw and I clamped a small piece of brass aound the end of the fishing line, drilled it and fixed it to the lever with the 14BA screw. The position of this screw along the lever determines the amount of vertical movement and was located to give a 2:1 reduction.
The tube was printed at an angle, so that it was underneath the lever at one end but protruded past it at the drivers end and the fishing line stuck up vertically just under the back of the driver.
Originally I had thought to simply drill an almost vertical hole in his body and put the line into that but it proved to be too stiff, so I had to fashion a very small knuckle joint and let one side into his body and clamp the line to the other side and this works very well.
Hopefully these two pictures will show what I've just tried to explain:
P1010005.JPG
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P1010007.JPG
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This all worked fine..... on the bench! However, I had a small problem in that if I glued the operating rod into the roof structure I would be unable to get at all this mechanism and I knew that would be asking for trouble. So I drilled the mounting hole in the roof, to take a small piece of 1mmID brass tube soldered inside a nested piece of larger ID tube (to give it a thicker wall). I then drilled and tapped it to take a grub screw and glued it into the roof hole.
Put it all together and gave it a try - Fine to begin with but then about halfway down everything siezed up. Trouble is it is difficult to see whats going on inside but eventually I realised that the curved roof support is exactly in line with the drivers head and he was jamming on it. So I printed a separate curved support and glued it in about 15mm further along and then when all set, carefully cut out the original one. Problem solved...except that although he could go flat and I knew there was sufficient room, he kept getting stuck about 3/4 of the way down. Eventually it dawned on me that he was bending forward into the downward curve of the far side of the roof and there was just not quite enough room. Solved that one by carefully slicing the superglue holding his feet to the brass floor and then even more carefully filing about 1mm from the soles of his shoes, thus tipping him forward very slightly and reducing the angle between his head and the roof. As the video shows, that seems to have fixed it.

If anything doesn't make sense please feel free to shout!
Philip

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Re: Austro Daimler Build project - VIDEO

Post by Lonsdaler » Wed Oct 26, 2022 4:15 pm

philipy wrote: Mon Oct 24, 2022 1:47 pm OK, as promised, herewith the video of this sardine can in operation. :lol:

[video][/video]

Early on in Andrew's original thread, long before I had any thoughts of actually building it, tongue in cheek I said that making the roof go up and down would be an R/c challenge. So, when I actually started the project I thought I'd better put my money where my mouth is, and then Rik made a comment that it would also need a telescopic driver....
🤣😂😅
Brilliant Philip. Congratulations on devising a most ingenious solution.
Phil

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Re: Austro Daimler Build project - VIDEO

Post by Trevor Thompson » Thu Oct 27, 2022 7:05 pm

That is brilliant. You must have spent some time thinking that one out.

Trevor

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Re: Austro Daimler Build project - VIDEO

Post by philipy » Thu Oct 27, 2022 7:39 pm

Trevor Thompson wrote: Thu Oct 27, 2022 7:05 pm That is brilliant. You must have spent some time thinking that one out.

Trevor
A lot of thinking and a lot of trial and error, I printed 5 or 6 versions of the U tube before I got it right! :oops:
Philip

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