Author Topic: Trevithick  (Read 8647 times)

Offline Brian Rupnow

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Trevithick
« on: August 25, 2020, 01:37:35 PM »
Does anyone have a 3d cad model of the Trevithick? It might be something I would consider building. I have done a fairly complete search of the internet, and found one set of plans in an Autocad format and one which is in a 3D format I can not open. My Solidworks Software is pretty versatile and can open most formats. a .step, a .X_t, or a .step would be nice.---Brian
« Last Edit: August 27, 2020, 02:14:42 PM by Brian Rupnow »

Offline techonehundred

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Re: Trevithick
« Reply #1 on: August 25, 2020, 08:23:16 PM »
I am sure you have already seen this link that has a downloadable STL file.

https://grabcad.com/library/trevithick-second-steam-locomotive-1

I also found this pdf, but on the drawing is an email address.  It looks like it was made on 3d cad.  Maybe the author could help.  It is from 2006, but worth a try.
https://pro-parovoz.ru/files/pdf/trevithick_second_steam_locomotive.pdf
« Last Edit: August 25, 2020, 08:38:25 PM by techonehundred »

Offline crueby

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Re: Trevithick
« Reply #2 on: August 25, 2020, 08:36:42 PM »
I have Autocad Fusion, can try opening/converting the file you were having trouble with. Can you send me a link?

Offline techonehundred

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Re: Trevithick
« Reply #3 on: August 25, 2020, 08:40:50 PM »
Chris, Here is a link to the Autocad I found.  Not sure if it is the same one that Brian found. but worth a try.

https://grabcad.com/library/trevithick-steam-locomotive-2

Offline crueby

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Re: Trevithick
« Reply #4 on: August 25, 2020, 09:15:54 PM »
Downloaded both from GrabCad - the locomotive-1 has a nice looking design in .stl format, Fusion had no trouble opening it, but the stl file version is a single body of the whole thing in mesh format, not individual bodies for the parts. Not sure if that will help you, Brian.

The locomotive-2 one is a .dwg file that Fusion can view, but it does not have 3D bodies that I can tell.

 

Offline JULIUS

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Re: Trevithick
« Reply #5 on: August 25, 2020, 09:48:48 PM »
Brian

The picture shown is from someone who took my drawings/design and redrew it using GrabaCad
I made two sets of drawings one design is for 10.25 inch gauge and one for 5 inch gauge.
The 10.25 is more a display model than a working model a but the 5 inch is a working model.
All my work is done in SolidWorks.
If you wish I can send you the PDF files first so you can have a look whether or not you like it.
I also can send you the SolidWorks 3D models. The models aer drawn in SolidWorks 2018.
Can you forward your e-mail address to me so that I can send you all the required information.

Kind regards

Julius

Offline Brian Rupnow

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Re: Trevithick
« Reply #6 on: August 25, 2020, 09:57:08 PM »
Julius--My Solidworks is 2015, so I can't open a newer version. However, if you could save the overall model as a .step or .x_t file I could open it. That would be very kind of you. I would probably take the 5" model and redo it to be driven by air, with a much simplified suspension, as I did the Stephenson's Rocket.---Brian  brupnow@rogers.com

Offline Pete49

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Re: Trevithick
« Reply #7 on: August 26, 2020, 04:32:57 AM »
Brian the .stl files are for 3D printers and is a set of gcode instructions to print it out.
You probably know this but just in case it helps.
I used to have a friend.....but the rope broke and he ran away :(

Offline Brian Rupnow

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Re: Trevithick
« Reply #8 on: August 26, 2020, 05:24:09 PM »
I don't have a 3D printer, and I don't have any CNC machines. I do have gear cutters and can cut my own 24DP gears in any size I choose. I have been doing a lot of searching for info about the Trevithick engine, and the only thing I'm not clear on is how the valve operated. The centrally located cylinder is double acting and has a pair of stabilizing guide rods fixed to the main structure on either side of the piston rod which act as a cross head guide . It also has a bow shaped piece across the front of the cylinder rod. A link from one end of that bow shaped piece goes back to a crank handle on the small gear, and a link from the other end of the bow runs back to the very large flywheel. So far, I'm not seeing anything that I recognize as a valve to reverse the pressurized steam into the other end of the cylinder.  Does anyone have more insight?

Offline Brian Rupnow

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Re: Trevithick
« Reply #9 on: August 26, 2020, 06:03:53 PM »
I just found an excellent animation of the steam valve on the engine. I haven't seen this done before, and I have to decide whether it is something I can build. The steam valve is combined with and part of he cylinder, all in the same bore.
« Last Edit: August 27, 2020, 02:42:05 PM by Brian Rupnow »

Offline Brian Rupnow

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Re: Trevithick
« Reply #10 on: August 27, 2020, 03:22:13 PM »
As in all things, I have to determine what scale I want to build this engine at. That is going to be easy for me this time, because the largest gear I can cut on my milling machine is 108 teeth, which is 4.584" outer diameter. All other components will have to be scaled to accommodate this known part size.

Offline Brian Rupnow

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Re: Trevithick
« Reply #11 on: August 27, 2020, 04:29:39 PM »
So, based on ratio and proportion, and the fact that my largest gear is going to have 108 teeth, this lets me establish that the smaller gears at the drive wheels are going to be 50 teeth and the small drive gear is going to be a 36 tooth. All three of these gears are tied to the large gear by a function of adding the pitch diameters together and dividing by 2. I arbitrarily select the horizontal distance between gears, and so now they are fixed in position and can not be moved. No thought has been given to the width of the Trevithick yet, because that will be dependent on the diameter of the boiler.

Offline Jasonb

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Re: Trevithick
« Reply #12 on: August 27, 2020, 05:01:10 PM »
Why are you limited to 108 teeth? on something like this cranking the rotary table without index plates would be OK so something like 180 teeth (2 degree) increments would be easy enough.

If there is a real reason to be limited to 108T then change the DP so you can get a larger diameter

Other drawings for this engine use 115/33/50 gears so slightly different proportions to yours.
« Last Edit: August 27, 2020, 05:05:42 PM by Jasonb »

Offline Brian Rupnow

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Re: Trevithick
« Reply #13 on: August 27, 2020, 06:19:53 PM »
The largest gear I've actually MADE is 108 tooth. So far we don't have much, but the basic proportions are blocked out. If I don't go and eat some lunch I'm going to fall of my chair!!

Offline Brian Rupnow

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Re: Trevithick
« Reply #14 on: August 27, 2020, 06:58:38 PM »
Hi Jason--I'm more or less just eyeballing pdf files for my dimensions and ratios. Do you have anything on this cylinder and valve assembly that you could share with me. I've watched the animation a dozen times, and it looks like something I could "imagineer" from scratch, but life would get a whole lot simpler if I had a set of details for reference.---Brian