Muncaster's Simple Entablature Engine

With the build series for my rendition of Muncaster's "Simple" Entablature Engine about to begin in ME 4618 I have started this thread for anyone who may have queries or comments about the engine such as alternative materials or construction methods to suit what tools you have.

Additionally I will post extra photos that would have possibly packed out the article too much but that may still be of use to those building the Engine. Martin is kindly publishing in consecutive magazines so that the build won't be spread over too long a period.

For those that have not seen my previous posts of the engine here is a video of it running of 2-3psi of air to wet your appetite and hopefully tempt you to give it a go.

 

The naked engine will give a good idea of what materials were used in it's construction

And if you prefer a sketch to the 3D rendering that is shown in the magazine then this is for you

 

Edited By JasonB on 25/07/2019 19:05:12

Additional content to go with part 1

8mm 6082-T6 aluminium plate with the material for the base Plate cut out.

Initial cuts to bring front and back edges to size

Clamps moved to do the sides

Freehand ground cutter used to form the 2mm radius decorative moulding, again clamps moved to suit.

Countersinking the underside of the six cylinder fixing holes for socket head csk screws as they won't be seen.

The almost completed base plate

Adding the exhaust pipe hole, other builders should do this at the time all the other base holes are added unless they want to use a different route for the exhaust

J

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Hi Jason.

That sounds good, issue 4618. I don't take M.E. mag on a regular basis but as this engine has captured my interest I'll get 4618 when it comes out. Do you know how many issues will cover the whole engine build?

I notice you have deviated from the standard muncaster pedestals. Having the split line on the central bearing and the housing at the same level seems to me a much better arrangement. The muncaster pedestals look unnecessarily complicated and would for me be difficult to make.

I assume you have scaled up the muncaster drawings 1/32" = 1mm which increases the bore size from 3/4" to your "favoured" 24mm.

Yes, looks interesting Jason and like others I welcome the addition of this supplementary build thread.

Geoff

Thank's for the interest Geoff, not sure how many issues it will get spread over but maybe 8-9 if Martin continues to give it 3 pages per issue, there are 15 drawings and two are in the first instalment but there is not so much text associated with those parts

Yes the pedestals are a bit easier to make that way and I also left them square sided rather than having to turn them, though with the basic mechanicals set out on my drawings the model could be embelished if the builder wanted.

Yes 1/32" = 1mm as it's a more manageable size and more beginners are likely to be brought up with the metric system and using metric tools and machines. It could also be enlarged working at 1mm=1/16" or reduced back to the original.

J

Where's the flywheel from Jason?

There will be a link in the installment with the flywheel but this e-bay seller usually has them but sods law he does not have one listed at the moment. He used to do the casting for College Engineering before they changed hands.

Thanks Jason, yes it's a shame about College Engineering, there were some useful castings that are now always out of stock.

Jason, I dont want to interrupt this thread but with the running video you mention running off 2-3 psi, is that the norm with small stationary engines i.e only needing low pressure to run. I imagined they would need quite a bit more than that but obviously not.

Ron

I made a Williamson engine many years ago, no piston rings or piston rod packing, just good fit. It will just run on lung pressure

For display when the engine is not running under any load you don't need much pressure and if it has been made well with minimum friction will not require much force to turn it over.

As soon as you put a load onto it you will need up up the pressure as you can't get effort out if you don't put effort in.

Another question. This one about design layout. Why is the power side only supported on one side ie outboard and the valve gear is on a shaft supported between bearings? Ease of alignment? Simplicity to buid? So it can be seen easier?

Nice engine, but design seems odd, to me.  Even though I know there are umpteen small engines with no rear crank support

Edited By not done it yet on 30/07/2019 17:50:17

As this is his "simple" design it is a lot easier to make a crank with just one web on the end of the shaft and a pin into that than would be needed if say the cylinder were set centrally between the columns. On the full size it probably kept the costs down and made erection on site a lot easier.

If I write up a few more of the similar sized Series 24mm bore engines than construction will become a little more complicated with each as cylinders become fabricated and the cranks sit between bearings. And maybe move on to ones that need more exacting fits such as hot air and IC engines.

Edited By JasonB on 30/07/2019 19:02:49

Really nice work Jason, I like the design especially as it is open to view to see how the mechanism operates.

If I do make one how big is the flywheel? I was wondering if it could be CNC'd on my KX1? If the castings aren't available.

Ian

You might be a bit tight on the Y-axis as it is 115mm OD but if starting with a circular blank about 100mm on the Y-axis may be enough using a 6mm cutter.

I suppose the spokes could be cut from plate and set into a rim in which case assuming you start with a turned disc then with a 6mm dia cutter you would only need 90mm movement.

A Minnie flywheel would be about the same size though does not have the curved spokes which are quite nice.

Yes the curved spokes are very pretty, that's why I was thinking about CNC if castings aren't available, most things can be machined from solid, but like you say space is a bit tight on a little KX1.

Another option may be to set up the blank so it can be indexed 6 times and just run code so that it cuts one spoke and half of each space either side, then index around an run the code again.

I'll sort you out the STEP file tomorrow if you want to play with the CAM

Jason,

That looks very nice. Do you have any video showing how you produced the radius around the cylinder mounting on the base plate and then changed from external radius to internal radius's and achieved it all nicely flowing from one radius to the next. Or was this done on your CNC machine?

Colin

Good idea! and yes please I'll have a play with the step file that's very kind of you. I'm using Vectric Vcarve if that makes any difference?

I've been playing around with the KX1 doing some plastic engraving over the past few days so it will make a change to do some metal stuff.

Ian

Another question. This one about design layout. Why is the power side only supported on one side ie outboard and the valve gear is on a shaft supported between bearings? Ease of alignment? Simplicity to buid? So it can be seen easier? Nice engine, but design seems odd, to me. Even though I know there are umpteen small engines with no rear crank support.

The outboard crank design was also used on big engines, like the Case 150 HP road locomotive shown in this Youtube video

Paul.

**LINK**