Muncaster's Simple Entablature Engine

Hi Jason and All,

I've had my eye on this engine for for quite some time so when I heard you had a series of articles in M.E. magazine I was naturally interested to see what building and machining methods you would use.

As far as the size was concerned I always favoured making the engine close to the original dimensions in Muncasters book. As you will know this was a 3/4" stroke and bore engine and is around 3/4 of the size of your 24mm bore design. I just prefer the smaller scale, something you can place on the palm of your hand.

The photo below is of the completed framework. I will be making the top end parts next, bearing pedestals, bearings crankshaft, crank etc., all to your building design but more or less 3/4 of all the sizes. I shall retain the original throw 9.5mm and probably the original bore 19mm (3/4".

I have to say I was very sceptical of your "flexed" taper turning method, did you get that from a textbook? Not a problem, works fine but I left the spigot off the top and drilled and tapped for a 4 BA screw.

The base is laminated from M.S. as you suggested the parts being rivetted together with 1/8" csk. head rivets, just like we used in school metalwork lessons all those years ago.

Photo in the next post, not uploaded yet.

Geoff

My muncaster frame 3/4 size

geoff

Looking good Geoff, should not be too hard to scale my sizes back down as 1mm will equal 1/32" an dI tried to keep to whole units in most cases.

You will have to plug the hole under the cylinder as I did not include a cylinder bottom, alternative would be to add a thin cover and reduce the conrod and guide bar length to suit.

Hi Jason,

Just reading the latest M.E.

I notice that you have again used the boring head in a very creative manner. This time to shape the exterior of the stuffing box bosses on the valve chest. clever stuff, I really must get a boring head for my sx2, looks to be a really useful piece of kit.

I wiil be interested to see how you made the cross head guides and then aligned them accurately. I have a idea how to do it but will wait and see how you have it done before I order some stock.

Enjoying the articles J, thank you

Geoff

Got to know you ar eenjoying the build and learning a few new methods along the way.

Hopefully the text will explain my methods with the guides and highlight where the critical items are, if not just ask away.

I did not post any extra photos to go with the last part as most were used in the mag but this one shows the finished chest and cover in place (temporary screws)

Additional content to go with part 5

Initial turning and threading of the cross head before transferring to the mill

Another shot of the crosshead being reamed for the pin

Asembled crosshead, conrod and big end bearings

There are very nice Cast Iron spiral spoked flywheels available on this side of the pond from Martin Model and Pattern in the appropriate size.

Assuming this side of the pond meaning the US of A!

Thank's Robert I had seen those before as they are also sold by Little Machine Shop as well as M&M Though the rim is a bit heavier.

Out of interest I did also run the CAM and generate the code to cut the spokes into a pre turned blank and it looks good on the screen.

What would be the options for a spiral flywheel in the UK Jason?

What would be the options for a spiral flywheel in the UK Jason

Good luck with that rocking I can't find one at the usual suppliers.

I thought Reeves had one but can't see it on their website

Geoff

Same place as when you asked last time on the first page

I messaged Lee and he says he has no flywheels listed at the moment as out of the country until the middle of the month. he will cast some more when he gets back. I will keep you all informed. Please not I have no links with lee, just a satisfied customer. he used to do the casting for College Engineering before they changed hands as it was one of the flywheels they sold.

Yes Jason, I did remember but assumed that Lee wasn't going to make them any more and was clearing surplus stock. My mistake, your fault.

Iv'e never cut a cylinder from bar stock before, but seemingly "the process may look a bit daunting"

but "the process is quite simple" not for me!

he goes-

cut a hole

oh dear! port face won't be big enough

start again

better

port face big enough

Ok it's not perfect port face is 0.2mm too wide and if you look close iv'e nicked the inside of the bottom flange, but that will be covered any how. so on the whole to say I've never done this before i'm quite pleased with the results, I'm going to leave the holes for the steam chest till later when I decide weather to make the chest 0.2mm wider or not. the exhaust is drilled but not tapped yet, a bit of fettling, honing and jobs a good un.

cheers Jason

You are off to a good start, I doubt the 0.2mm will make a lot of difference so upto you if you make the chest and cover wider or to drawing.

I have just had a message from Lee to say that he can cast in most materials to your own supplied patterns. I've only had CI from him which was cleanly cast and a nice bit of iron to machine. Anyone with deep pockets and a liking for a bit of bling could ask for a bronze flywheel. he can be contacted by message on e-bay here

Hi Paul, nice work on the cylinder as Jason said that's a good start.

I'm following Jason's building methods but scaling his sizes down to approximately 3/4 full size.

As I didn't have a suitable piece of cast iron in stock for the cylinder so I decided to treat myself to a 10v cylinder which is just about the right size at 19mm stroke and bore. Got that machined up and have made the valve chest to Jason.s design. Also made some progress on the bearing blocks which were tricky to make as they are quite small.

Still looking for a 3" flywheel and may use the 10v one which I have had for some time.

Jason I took note of your comments in the latest M.E. regarding the use of B.M.S. for the crosshead guides. It was a good point I assume the the cold roll steel is less stressed and thus not as liable to distort.

Once again some good machining ideas in the latest issue in particular the way you made the crankshaft.

Geoff

Some mor egood progress there Geoff and good use of the casting, I would think that anyone building to my size may be able to make use of a Stuart No7 cylinder as there should be enough metal there for the slightly smaller bore or make it 25mm instead of 24mm.You don't want to believe everything you read in magazines that should have been HOT rolled as that does have less stress so not a slikely to distort as cold rolled (bright) bar.

Another option for those wanting curved spoke flywheels is to fabricate, Find's site has a good guide

Extra photos to go with part 6

Milling the recess in the valve

Held the other way up the slots for rod and nut can be added. If a vice stop is positioned before the part is removed from the vice after machining the recess you can put it back in and keep the X axis datum, Y still stays the same as fixed jaw will still locate the work in that axis.

Marked out eccentric material to give a guide of where to machine to

Completed eccentric strap, eccentric and rod. Note position of grub screw at the highest point of the eccentric which will help with setting the timing in the final part 7.

Hi Jason,

In ME 4621 pp 457 Why are crosshead guides not symmetrical? ( mirror image )

Diamension 55.3 + 23.5 does not add up to 79.5 mm.

REGARDS,

John Chappell

Welcome to the forum John, Are you having a go at making this one?

The two dimensions don't add up as one is to the internal corner and the other to the external as these are the extents of the two cuts I dimensioned it that way to give builders the sizes to cut. Will post a better detail later but this is the blown up drawing