Author Topic: Lockdown Hit-and-Miss Engine from bar stock  (Read 4549 times)

Offline Misterg

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Lockdown Hit-and-Miss Engine from bar stock
« on: September 26, 2020, 09:48:13 PM »
Hi folks,

Here are some pictures of the horizontal engine that I have just finished.

I designed it from scratch and built it from bar stock on my 7 x 14 Chinese lathe as a distraction from the Covid 19 lock-down.

Stats:
Bore: 20.4 mm / 0.8"
Stroke: 26 mm / 1.02"
Displacement: 8.5 cc
Compression ratio 4:1

The main structure is made from 50 x 38 x 6 extruded aluminium 'U' section and the cylinder block and head are made from 38 x 38 mm aluminium square bar. The cylinder liner and the crank are steel, and the piston is cast iron, sealed with a viton O-ring.

The flywheels are cast iron trolley jack wheels.

I anodised all of the aluminium parts using the process described by Mark Presling on Youtube.

The Hobby King ignition module had to be shaved down to fit under the engine bed. Batteries are let into the underside of the base.

























It even runs!

(I'm using Coleman fuel with a few percent marine two stroke oil to try and keep the valves and top-end lubricated.)

[youtube1]https://youtu.be/orubaHfOTU4[/youtube1]

VERY pleased with the way it has turned out!  :)

Andy
« Last Edit: September 26, 2020, 09:54:56 PM by Misterg »

Offline crueby

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Re: Lockdown Hit-and-Miss Engine from bar stock
« Reply #1 on: September 26, 2020, 10:52:38 PM »
Wonderful job!   :ThumbsUp:

Offline propforward

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Re: Lockdown Hit-and-Miss Engine from bar stock
« Reply #2 on: September 26, 2020, 11:52:45 PM »
That’s a phenomenal engine.  Very well done.
Stuart

Forging ahead regardless.

Offline Misterg

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Re: Lockdown Hit-and-Miss Engine from bar stock
« Reply #3 on: September 27, 2020, 01:20:34 AM »
Thank you both ever so much!   :cartwheel:

I'me very pleased with how it turned out!  :cheers:

Offline propforward

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Re: Lockdown Hit-and-Miss Engine from bar stock
« Reply #4 on: September 27, 2020, 01:29:25 AM »
Looking at it I would say you have a lot of machining experience. Or you’re a natural. The fit and finish is top notch. I’ve not managed to achieve that. Very impressed.
Stuart

Forging ahead regardless.

Offline cnr6400

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Re: Lockdown Hit-and-Miss Engine from bar stock
« Reply #5 on: September 27, 2020, 02:00:10 AM »
Outstanding workmanship MrG. Well done!   :ThumbsUp: :ThumbsUp: :ThumbsUp:
"I've cut that stock three times, and it's still too short!"

Offline rudydubya

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Re: Lockdown Hit-and-Miss Engine from bar stock
« Reply #6 on: September 27, 2020, 07:39:01 AM »
Nicely done, Andy.  Great hit and miss action and fine workmanship.   :ThumbsUp:

Regards,
Rudy

Offline Jasonb

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Re: Lockdown Hit-and-Miss Engine from bar stock
« Reply #7 on: September 27, 2020, 08:02:50 AM »
Now that you have posted a few more details here than on ME it makes it even more impressive, I thought it was a stain black PAINT job. Did you base it on any particular engine's mechanicals, has a bit of Zero-six or Redwing look to it?

Just goes to show what can be done on basic machines if you put your mind to it and no mention of a mill so I assume all milling was also done on the lathe, not bad for a boat anchor ;)

Offline Robert Hornby

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Re: Lockdown Hit-and-Miss Engine from bar stock
« Reply #8 on: September 27, 2020, 08:16:22 AM »
Brilliant Jason,
I love the design and workmanship. A beautiful engine
Robert
Age and treachery will always overcome youth and skill

Offline Zephyrin

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Re: Lockdown Hit-and-Miss Engine from bar stock
« Reply #9 on: September 27, 2020, 10:22:47 AM »
very nice engine, and fine runner !
does the loop in the gas pipe comes from experiments ?

Offline Misterg

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Re: Lockdown Hit-and-Miss Engine from bar stock
« Reply #10 on: September 27, 2020, 11:04:10 AM »
Thank you!

 :cheers:

Did you base it on any particular engine's mechanicals, has a bit of Zero-six or Redwing look to it?

I set off looking for something that could use the 3" diameter trolley jack wheels as flywheels.

From various build logs I found various snippets of the main details of various designs (Upshur Farm engine, Farm Boy, Odds n Ends, Economy, Webster, Kerzel and RLE). I would have tried to build the Kerzel engine, but as you've guessed, I don't have a mill, and there are quite a few features that would be difficult without one in most of the above. (I wasn't aware of the Zero-six at the time, and I don't think I could find out much about the Redwing.)

Somewhere about 1/2" to 3/4" bore seemed about the right match for the flywheels, and when I started looking at fitting in inserted valve cages in the head, it became obvious that 1/2" bore would be a very tight squeeze (I didn't want to go down the valve box route). The engines that I thought ran the most nicely had a stroke:bore ratio of 1.4:1 or higher - I had a length of 42mm diameter free machining steel for the crank webs which would give me a stroke of 26mm with counter-weighted crank webs (another feature that appeals to me), so a bore of ~19mm / 3/4" would work. Some comments from the designer of RLE (I forget his name...) suggested a 4:1 compression ratio would run OK, and make the engine more docile than higher ratios. Everything else just falls out of those assumptions. I tried to be clever and bought a length of 19mm bore CDS tube for the cylinder liner, hoping to use it 'as received', but the bore was oval, and the internal finish was poor, so I ended up having to bore it out anyway - hence the 20.4mm bore!

Edit to add: I modelled my ideas and honed them to the final design in Fusion360 which helped immensely.

I'm not a 'machinist', but have amused myself by making stuff all my life. The challenge (for me) is to make what you want with what you've got (hence the weird looking governor).

Quote
not bad for a boat anchor ;)

 Thanks! ;D I think back to when I was dabbling with steam engines in my teens - people would have been fighting with each other to get hold of a machine like this for what would have been ~£200 at the time. (They are not without 'issues', but are a big step up from no lathe at all!).

« Last Edit: September 27, 2020, 11:20:58 AM by Misterg »

Offline Misterg

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Re: Lockdown Hit-and-Miss Engine from bar stock
« Reply #11 on: September 27, 2020, 11:10:49 AM »
very nice engine, and fine runner !
does the loop in the gas pipe comes from experiments ?

Thank you!  :cheers:

I have seen comments about a loop in the fuel pipe 'helping' with hit and miss engines, but this loop is purely for aesthetics and to give me a bit of wriggle room in lining the pipe up with the 'carb'.

(There is a check valve inside the connection on the 'carb' to try to avoid fuel draining back during the 'miss' cycles, though, which does seem to work.)

Online Jo

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Re: Lockdown Hit-and-Miss Engine from bar stock
« Reply #12 on: September 27, 2020, 11:14:00 AM »
Nice engine  8)

I think back to when I was dabbling with steam engines in my teens - people would have been fighting with each other to get hold of a machine like this for what would have been ~£200 at the time. (They are not without 'issues', but are a big step up from no lathe at all!).

As with everything you get what you pay for but once you are aware of the shortfalls it is amazing what can be done  :)

Jo

P.S. You can pay a lot of money and get a poor lathe as well  :wallbang:
Enjoyment is more important than achievement.

Offline Tom1948

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Re: Lockdown Hit-and-Miss Engine from bar stock
« Reply #13 on: September 27, 2020, 11:49:42 AM »
Great job! I admire your talent. If i might ask, how long did it take to build?

Offline Misterg

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Re: Lockdown Hit-and-Miss Engine from bar stock
« Reply #14 on: September 27, 2020, 12:41:54 PM »
Great job! I admire your talent. If i might ask, how long did it take to build?

Thank you :)

It took about 3 months - I machined the first parts in mid June, and finished it a week, or so ago.

Offline Roger B

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Re: Lockdown Hit-and-Miss Engine from bar stock
« Reply #15 on: September 27, 2020, 02:07:27 PM »
Very nicely done  :praise2:  :praise2:  :wine1:

Do you have any thoughts for your next project?
Best regards

Roger

Offline Misterg

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Re: Lockdown Hit-and-Miss Engine from bar stock
« Reply #16 on: September 27, 2020, 10:18:09 PM »
Do you have any thoughts for your next project?

Thank you very much, Roger  :cheers:

I have a few things on my list that I'd like to make - a vacuum / flame eater engine, a low temperature Stirling, a marble Stirling, and a parallel twin of some sort with a side cam shaft driven by skew gears (I'm awed by the Ruston & Hornsby twins), but I'm not sure which will be next. I have a long term ambition to make a 1 cylinder long slice of a Deltic type engine (probably spark ignition, rather than diesel though), but that is very much pie in the sky at the moment!

Offline scc

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Re: Lockdown Hit-and-Miss Engine from bar stock
« Reply #17 on: September 28, 2020, 05:23:36 PM »
A lovely engine, well made and beautifuly finished, and a cracking runner as well :praise2:    I fully agree with "using what you've got"  and keeping things in house.    Well Done :cheers:        Terry

 

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