Author Topic: A Beginner's First Engine (Single-acting Oscillator)  (Read 4465 times)

Offline gary.a.ayres

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A Beginner's First Engine (Single-acting Oscillator)
« on: February 10, 2019, 11:34:07 PM »
This is my first ever attempt at building an engine, so I decided to keep it as simple as possible and start with a half inch (12mm) single acting oscillator. Given the levels of knowledge and skill that many of you have I suspect you may find such a basic build less than exciting, though I am adding a couple of touches of my own to the project which may take it a little bit away from the ordinary.

Fundamentally the engine will be a version of the single-acting oscillator designed by Steve of Steve's Workshop http://steves-workshop.co.uk/steammodels/simpleoscil/simpleoscil.htm, where plans and guidance are posted. My main reason for choosing this version out of the many similar engines that are out there is that like most of my tooling, it's metric. My version differs from Steve's original in a few non-critical dimensions due to the materials I have available. I have also opted for a particular look of my own devising which has nothing whatsoever to do with functionality. Call it steam meets dieselpunk meets Flash Gordon...

I marked out the frame on 12mm aluminium plate and the pulley on a slice of brass bar, making sure that the frame was bigger in all dimensions than the rectangular frame of the original:



I can hear you gasp at what is to all appearances a very scrappy bit of marking out. However, there was method in my madness. CNC would be perfect here (one day...) but I used the same approach that I have used to create irregular but clean-edged forms in abstract paintings such as 'Trident', below, where I would sketch roughly on the canvas in pencil first, then gradually refine the lines with paint until I got the forms I wanted:



 I did the same with the engine frame,  but instead of refining the form with acrylic paint and brushes, I tried a variety of tools and methods before settling on a combination of chain drilling and small drum sanders of various sizes held in the mill chuck. I'd rather have used my drill press for this but the vibration shook the MT3 shank  of the chuck out of the spindle (why don't drill presses have drawbars as standard...?).

If the flywheel looks oversized relative to the frame it's because it is. It needs to be turned down to size.

The bottom of the frame needed to be trued up then drilled and tapped to to make two threaded mounting holes to attach it to the base. I attached it upside down to an angle plate using two toolmaker's clamps, then checked the level of the scribed line with a height gauge before squaring the piece with an endmill and drilling and tapping it M5:





A recess was then milled in the flywheel using my small rotary table with its four-jaw self-centring chuck:



And that's as far as I have got so far. Pictures below. A reasonable start I suppose:







 :)




Offline crueby

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #1 on: February 10, 2019, 11:43:11 PM »
Good choice on a first engine, its where most of us started out, you will learn from it and move up quickly, jusdging by your other work!
 :popcorn: :popcorn:

Offline Gas_mantle

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #2 on: February 10, 2019, 11:46:25 PM »
Looking good Gary, it's nice to see a new approach to standard design  :)

Offline Johnmcc69

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #3 on: February 10, 2019, 11:52:39 PM »
 :ThumbsUp:
Excellent start Gary! Parts looking good!

 John

Offline AOG

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #4 on: February 10, 2019, 11:57:21 PM »
Itís looking good but I do have a general suggestion based on my own painful experience. When you are going to do a shaped part like that do the shaping last. Start by squaring up a rectangular blank. The straight edges make it very easy to align and hold the part while you put in the interior holes and features. When those are in then shape the outside. It isnít going to be much of a problem with the part you are making now but trust me, the lack of good square references can bite you.

Tony

Offline gary.a.ayres

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #5 on: February 11, 2019, 12:04:27 AM »
Many thanks gentlemen.

@ Tony - yes, that makes sense. Next time...!

Offline b.lindsey

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #6 on: February 11, 2019, 12:58:04 AM »
Always enjoy watching first engines Gary. I am excited along with you and will definitely be following along.

Bill

Offline 10KPete

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #7 on: February 11, 2019, 03:04:52 AM »
 :popcorn: :popcorn:

Pete
Craftsman, Tinkerer, Curious Person.
Retired, finally!
SB 10K lathe, Benchmaster mill. And stuff.

Offline gary.a.ayres

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #8 on: February 11, 2019, 09:30:43 AM »
Many thanks guys - very kind of you.

gary

Offline Ramon

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #9 on: February 11, 2019, 10:05:10 AM »
Congratulations on making that start on your first engine Gary :ThumbsUp: I remember it well. Believe me when you see it run for the first time you will have a grin from ear to ear :D

I would reiterate the sound advice offered by Tony - get the parameters right before letting those obvious creative juices you possess take hold - work the outside to the details and not the other way round  ;)

Good luck with the rest of your build - your perseverance with your boiler will hold you in good stead :ThumbsUp:

Tug
"I ain't here for the long time but I am here for a good time"
(a very apt phrase - thanks to a well meaning MEM friend)

Offline gary.a.ayres

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #10 on: February 11, 2019, 10:21:29 AM »
Thanks for this Ramon - much appreciated.

Now that it has been pointed out to me it's very clear that it's better to keep things square for as long as possible and leave the fancy stuff to the end. I reckon I'll get away with it this time, as Tony says, but I can see how it could be a big problem with more complex parts.

I was partly driven by enthusiasm for my idea but also partly by uncertainty about how easy it would or wouldn't be to make curves of this kind in aluminium plate given the limits on the equipment I have. I didn't want to drill all the ports and so on, only to then spoil the piece when trying to shape it. Now that I have found a way of making these curves it should be easier to leave it until the end in future builds.

Cheers,

gary

 :ThumbsUp:

Offline gary.a.ayres

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #11 on: February 11, 2019, 10:31:08 AM »
Believe me when you see it run for the first time you will have a grin from ear to ear :D

Tug

PS - yes - I can't wait for that moment!   :)

Offline gary.a.ayres

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #12 on: February 11, 2019, 11:46:43 PM »
Another session today. First, a recess was milled on the flip side of the flywheel to match the first one:



Most of the subsequent work on the flywheel will be done on the lathe. To try to avoid a wobble, I intend to turn it in one setting, between centres on an arbour made of the same stock as the main axle.

The base was then marked out on a piece of the same aluminium plate as was used for the frame. It was also marked out in a similar style. Gives new meaning to the term 'scratch built'. Or maybe that's where the term came from in the first place:



I swear I'm starting to like the smell of that stuff just a bit too much...

This time, as I had only external curves to deal with, I used a coarse grit on the belt sanding attachment of my Coronet Major woodturning lathe to shape the piece, followed by a medium grit flap wheel in the drill press. As it happened I did not work to the scribed lines because a pleasing shape began to emerge before I reached them, so I just flipped the part over, gave it a few more passes on the sander and called it done, minus the finishing. I used M5 transfer screws to transfer the hole positions from the bottom of the frame to the base:



The position of the frame on the base was judged by eye, but the distance between the holes needed to be retained, hence the transfer screws. First time I've ever used them, but it will not be the last   :ThumbsUp:

Once the clearance holes were drilled, they were counterbored on the underside of the base to accommodate the heads of the M5 cap head screws:



Looks a bit spooky here, but less so since I cleaned off the layout fluid...

Finally, the frame was screwed to the base:










Offline crueby

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #13 on: February 11, 2019, 11:56:11 PM »
Great progress!


 :popcorn:

Offline b.lindsey

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #14 on: February 11, 2019, 11:56:20 PM »
Very nice looking shape to it Gary. I noticed on the second picture in this post it looks like a 3D effect. No doubt just the combination of colors and patterns but I did do a double take. Was looking on my phone though. Anyone else getting the same effect....kind of cool.

Bill