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Member postings for oliver p.

Here is a list of all the postings oliver p. has made in our forums. Click on a thread name to jump to the thread.

Thread: Hi from Oliver
06/08/2019 14:15:46
Posted by lfoggy on 05/08/2019 21:58:00:

Wow, your workshop facilities sound amazing.

thank you. However don't expect too much As I said, it is a machine factory owned by my family, and they make heavy (and large...) special purpose machines. Therefore, most of our machines in the workshop are big (there is a lathe for parts in the order of 1m diameter), so it can be a bit of a hassle when small parts need to be made. (there are smaller machines, though, but not many.) So the precision mechanics possibilities are a bit limited.

Thread: Rotary Valve engine having more than two cylinders
05/08/2019 09:52:14
Posted by mick H on 05/08/2019 09:29:53:

Yes, Oliver it is the same engine but I did make a few alterations / additions. Firstly I ran the crankshaft and crankshaft valve linkage in miniature bearings (arguments for and against). Secondly, I fitted Viton piston rings. There is a feed pump mounted on the RH side of the engine driven by an eccentric on the valve and a Roscoe lubricator fitted opposite the steam intake. I may also have tinkered with piston diameters but I can't remember the details.

Duncan is quite correct regarding the valve being a good fit. I lapped it in and have surprisingly minimal leakage, mainly at the feed pump end. I am working on an O ring based solution to this.

As regards the self starting problem, I have fitted a needle roller clutch (one way) bearing to the output end of the crankshaft which just requires a nudge from a servo to push the piston past TDC and away she goes.

The engine is shamefully filthy at the moment but if you would like a picture I will clean it up.

Mick

sounds very interesting! if you have some nice pictures that would be really interesting

05/08/2019 08:49:15

@ Mick

cool! have you used the very plans I posted in the link? and how did you overcome the starting problems?

I think if there are 3 or more cylinders, the engine will self-start no matter in which position it was stopped previously.

@ duncan

you are right. The valve does not really rotate in this case but oscillates. I think the construction could be a bit simpler if there is a separate valve for inlet and exhaust.

If I could post a screenshot of my 3D CAD model, we could probably figure out how the valve needs to be done, but so far I didn't find out how to attach a picture to a posting here

So do you think it should be possible to have this design with 3 or more cylinders?

Thread: Hi from Oliver
04/08/2019 19:37:13

Hi guys,

I am new to the forum, and it seems to me that it is usual here for new members to introduce themselves

So I am an electronics engineer, and at work I have only rarely to do with mechanics. But I my family owns a machine factory and so I have access to CNC lathes and milling machines and even spark erosion machines, and so one of my hobbies is to make different mechanical things; i.e. I have already made some Stirling motor models and I am now planning for something more advanced. This is why I joined the forum to ask questions

I don't have a particular use for my engine models, I make them just for fun

Best

Oliver

Thread: Rotary Valve engine having more than two cylinders
04/08/2019 19:30:57

Hi Guys,

I am new to the forum and this is my first question here

So I have already built several Stirling motor models, and I thought it would be time to make something "bigger". I have no particular application for it, just for fun. What I would like to do is a steam engine model having 3 or 4 cylinders. While I was searching on the web for some inspiration, I found this plan by accident:

http://www.john-tom.com/MyPlans/Steam%20Engines/RotaryValveEngine.pdf

It looks very nice, but has two cylinders only. But I like the "Rotary Valve" it has, so I wonder whether it would be possible to extend this design to 3 or even 4 cylinders. I already started to make some simple 3D drawings to figure out how I should design the rotary valve, but so far I was not yet able to figure it out. So can anybody give some hints about this? is it possible?

For 2 cylinders, the notches in the rotary valve need to be 90 degrees apart from each other; so I assumed for 3 cylinders, 60 degrees would be appropriate, but this is not true (or I made a mistake ). I made a very simple 3D CAD drawing with all cylinders, pistons and everything, which allows me to simulate the whole thing and make an animation to figure out how the rotary valve needs to be designed. But so far I was unable to do it correctly any hints? I like the idea that there is no need for a separate valve for each cylinder but only one valve for all, and it looks a bit fancier, which I like as well.

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