Model Engine Maker

Help! => Specific Engine Help => Topic started by: Pedro on January 15, 2014, 12:24:45 AM

Title: SS Xantho John Penn trunk engine
Post by: Pedro on January 15, 2014, 12:24:45 AM
Hello there. I'm planning a build of a John Penn trunk engine, in particular the one from the SS Xantho in Oz. I've approached the WA museum but so far no reply. There are a number of Victorian engravings of larger engines which are detailed enough to do a good pastiche, but I was wondering if anyone has any info for this one. Apparantly drawings were made and a model built, but I can only find the one reference online.
It is a particularly iconic engine, since it was made for one of two batches- (the other by Maudslay) built for gunboats in the Crimean War. Innovations included high pressure working with no condenser, standardised Whitworth threads, and rudimentary mass production. So far the only info I have is 21" bore, 12" stroke, 11" trunk, a few photos of the rusty original, and a contemporary engraving of a much larger ship engine, though of similar style. Any ideas? 
Title: Re: SS Xantho John Penn trunk engine
Post by: steamer on January 15, 2014, 01:09:59 AM
I assume the engine still exists and is located at WA museum?....is visiting that museum an option?

Dave
Title: Re: SS Xantho John Penn trunk engine
Post by: steamer on January 15, 2014, 01:10:55 AM
Oh and feel free to tell us about yourself, and any other models that you've made.   8)

Dave
Title: Re: SS Xantho John Penn trunk engine
Post by: b.lindsey on January 15, 2014, 01:12:58 AM
Hi Pedro, Dave beat me to it...it would help to know where you are from also, and a brief introduction would be much appreciated also. In the meantime, welcome to MEM and best of luck on your search for information on this engine.

Bill
Title: Re: SS Xantho John Penn trunk engine
Post by: Pedro on January 15, 2014, 02:08:22 AM
Sorry guys, I'll do a proper intro tomorrow, it's late here in UK. Sadly, I can't afford to go to Oz. Thanks for the interest. Catch you later.
Title: Re: SS Xantho John Penn trunk engine
Post by: steamer on January 15, 2014, 02:11:32 AM
That may or may not be a problem, we may have some members there that can help.

Have a good night, talk to you tomorrow.

Dave
Title: Re: SS Xantho John Penn trunk engine
Post by: peatoluser on January 16, 2014, 04:24:52 PM
Perhaps not what you want to hear. I've often looked for drawings of horizontal marine engines but they seem to be thin on the ground.
the best I've seen are in a book 'modern marine compound engines being a supplement to modern marine engines ' by N.P. Burgh. published, I think in the mid 1870's.
If I remember correctly, there was a couple of horizontal engines drawn , 1/12 scale . quite detailed general arrangements with sectional views.
Don't get a print on demand version. the fold outs aren't folded out in the copying. Reference or university libraries might have a copy.
obviously they are compound engines with all the trappings of condensers , air pumps etc.
Also, in the science museum, London, there are some fine model marine engines including a horizontal trunk engine on display . well there was last time I went many years ago, but museums do change the odd exhibit.
Perhaps are friends in Oz might be able to help? specially after normal service has been resumed in the ashes!

regards

peter
Title: Re: SS Xantho John Penn trunk engine
Post by: PatJ on January 16, 2014, 04:36:21 PM
Here is a photo of the engine:
http://www.gracesguide.co.uk/File:Xantho01.jpg

and here is a link to a simulation of the ironclad Monadnock trunk engine (similar to the Monitor engine).
Y-kFOoEqAjI
It would not be difficult to modify the geometry for the Xantho engine (for some).
The photo provides sufficient information to design the engine.
Title: Re: SS Xantho John Penn trunk engine
Post by: PatJ on January 16, 2014, 04:50:07 PM
A restoration article here:

http://archive.is/1xJP

and here

http://museum.wa.gov.au/explore/broadhurst/ss-xantho-shipwreck

and book here

http://books.google.com/books?id=ZE1KwA7KNyYC&pg=PA160&lpg=PA160&dq=Xantho+trunk+Engine&source=bl&ots=W9s3ODefwK&sig=EiWU7G4gj8UXsyafT-nkkBLI_UM&hl=en&sa=X&ei=Rw_YUrPXMI6fkQe5rYHgBg&ved=0CEcQ6AEwBA#v=onepage&q=Xantho%20trunk%20Engine&f=false
Title: Re: SS Xantho John Penn trunk engine
Post by: PatJ on January 16, 2014, 05:49:01 PM
Looks like the model can be seen to the left in this photo, with the actual engine straight ahead.

https://www.facebook.com/media/set/?set=a.10151626559411296.1073741840.200677676295&type=3#!/photo.php?fbid=10151626559506296&set=a.10151626559411296.1073741840.200677676295&type=3&theater

A distant view of the model on the right:
https://www.facebook.com/photo.php?fbid=10151626559546296&set=a.10151626559411296.1073741840.200677676295&type=3&permPage=1
Title: Re: SS Xantho John Penn trunk engine
Post by: PatJ on January 16, 2014, 06:50:34 PM
This engine would not be that difficult to model with the information available.

Looking at the photo below, you can see that the exhaust pipes are the "Y" configuration, and the steam pipes are the ones going into the steam chest horizontally on either side of the engine.

http://www.gracesguide.co.uk/File:Xantho01.jpg

The bar across the back top of the engine would most likely be for the reversing gear.
I am assuming a reversing engine since there are two eccentrics per cylinder, although the Monitor engine also had two eccentrics per engine but used those for a double piggyback (what is the correct term for this type of vavle, Myers?) slide valve, and a clever reverse mechanism that was non-standard.

All you would have to do is model one cylinder and one of the three frame sections (in 3D modeling), and then copy the remaining items, since they are copies.

From the literature, it sounds like a standard D-valve.

The steam chests were a bit odd in shape, with an extension upward to connect to the steam pipe.
This extension would make for a weak casting, and a complicated casting too; not a good idea, but to be historically accurate, that is how it was done.

I wonder if it could have had a Stephenson's link?

Somebody down under needs to go by the museum and get some good photos of the model.

Pat J
Title: Re: SS Xantho John Penn trunk engine
Post by: PatJ on January 16, 2014, 08:48:39 PM
After a great deal of digging around, I found this excerpt from a thesis presented for the Degree of Masters of Philosophy, Murdock University, 1989, titled:
"Charles Edward Broadhurst (1826-1905), a remarkable nineteenth century failure".

This engine could absoulutely be modeled and built using the limited information available, especially this photo.

I was correct, the engine used a Stephenson's type links and was reversible via the rod across the top of the engine that has the reach rods (correct term)? on it.

Who is going to get started on the 3D model for this engine?

Pat J
Title: Re: SS Xantho John Penn trunk engine
Post by: steamer on January 16, 2014, 08:51:06 PM
I have a very good book on the history of the US steam navy up through WW1.   I know there are quite a few cuts of trunk guided engines like that, I can scan them.....if you're patient..... :ShakeHead:


Dave
Title: Re: SS Xantho John Penn trunk engine
Post by: Jasonb on January 16, 2014, 08:51:52 PM
What you mean you haven't started drawing it yet Pat :LittleDevil:
Title: Re: SS Xantho John Penn trunk engine
Post by: PatJ on January 16, 2014, 09:02:44 PM
Ok, I am foaming at the mouth over the info I found on the Xantho engine.

Not like I need another engine to model, but there is plenty of info to do this one.

Gosh, and I am in the middle of a work project right now, so I can't start on it yet.

Well I will decide next week once my work project goes out.

This would be a nice one to model/make.

I guess I would make the bore about 3" to keep the parts from getting too figgity (or maybe 2.5" bore).

Title: Re: SS Xantho John Penn trunk engine
Post by: Gippy on January 16, 2014, 11:21:24 PM
Big fan of John Penn.
Will be watching with interest.
thanks for thread.
Gippy
Title: Re: SS Xantho John Penn trunk engine
Post by: Pedro on January 17, 2014, 02:34:29 AM
Wow folks I'm deeply impressed by the level of response. Thanks for all the posts. You found much better pics than I could find. I've been offline 'cos the hated Windows finally died but I've got a Linux now and wish I'd done it ages ago.
My interest in this engine was in fact sparked by Ericsson's monitor engines, and when I saw an engraving of Penn's was stricken by the elegance of it. (Also that it's within my capability to do a reasonable if not fantastic replica.) One major difference with the engravings of other Penn engines (of which I have one from *The Engineer* Dec24 1897) is the more substantial framing, which is perhaps due to the higher pressure or just scaling, it being small after all.
Drawings definitely did exist, so I'm having another try at the museum. It was 20 years ago, so maybe they're just not on the boil any more and need a little prompting.
There was also a Model Engineer article on the original and the model (3 June 1994). I'm currently waiting for it to arrive.
  Not surprisingly, sealing the trunks is reported as being an issue, and while it's no big deal on a model, I feel that modern ptfe rod seals should crack it for a working engine.
When I started looking I naively assumed that models of this type would be common, but so far it seems not.
Once again, many thanks and it looks like I' m not the only one feeling inspired!    Ps special thanks to PatJ
Title: Re: SS Xantho John Penn trunk engine
Post by: Pedro on January 17, 2014, 09:22:36 AM
I have a very good book on the history of the US steam navy up through WW1.   I know there are quite a few cuts of trunk guided engines like that, I can scan them.....if you're patient..... :ShakeHead:


Dave
    Thanks for the offer but I suspect the US engines are of Ericsson's monitor type, though they themselves seem not to have been modelled much, other than Rich Carlstedt's fabulous example.
Title: Re: SS Xantho John Penn trunk engine
Post by: PatJ on January 17, 2014, 12:29:08 PM
Pedro

Thanks for pointing out this interesting bit of history.
Facinating engine and story that goes along with it.

I did a lot of research on the Monitor trunk engine a few years ago, and even started making a bar stock engine.
Then I got into 3D modeling and castings, and discarded what I had started.

I think Rich saw a model of the Monitor engine in a museum in the US, and then built his own model.
I got to see Rich's model and what a fabulous engine it is.
The detailing on that engine is extraordinary.
Rich is suppose to be working on a 3D model of that engine, and I have not persued the Monitor or Monadnock since any 3D model that Rich makes would be far more detailed, and he has talked of publishing plans some day.

If nothing else, I would like to rough out the geometry for this engine to get it to a functional stage.
I can do that fairly quickly with Solidworks.  The fine detailing would still have to be added, but at least the major parts of the engine could be assembled and run in simulation to know that it will work well.

Maybe if I get some time in the next few weeks I will look at it again.

Thanks again for bringing this engine to light.

Pat J
Title: Re: SS Xantho John Penn trunk engine
Post by: steamer on January 17, 2014, 01:13:56 PM
I have a very good book on the history of the US steam navy up through WW1.   I know there are quite a few cuts of trunk guided engines like that, I can scan them.....if you're patient..... :ShakeHead:


Dave
    Thanks for the offer but I suspect the US engines are of Ericsson's monitor type, though they themselves seem not to have been modelled much, other than Rich Carlstedt's fabulous example.

I don't know about that.    The US was in its infancy steam wise....we copied or bought a lot of equipement .....right up into the early 1900's
I'll dig up this book over a brew this weekend..and see....but I have a race truck to prep first... :ShakeHead:

Dave
Title: Re: SS Xantho John Penn trunk engine
Post by: Pedro on January 17, 2014, 03:25:53 PM
PatJ, I'm delighted in the interest in the topic. My first enquiry was with the ME forum, and the lack of interest was resounding, other than a suggestion to try this site. I remain surprised that trunk engine models are so rare when there are loads of models of other types, particularly since it appears the design lends itself to machining from barstock by manual machines.
Assuming the reported 21"*11"*12" dimensions are true, 1/8 scale looks like a good choice, giving 2 5/8" bore and 1 3/8" trunk, so commercial seals should be available. Speaking of which, are they a bad idea? My pump background suggests that they should be fine. There is one type that is basically a standard O ring with a filled TFE working face bonded either to the ID or OD. (eg O.L.seals.dk) which look promising. Stainless for the piston is an obvious choice with such seals, and possibly even the cylinder. Any comments would be gratefully appreciated.
I'm still trying the museum. If nothing else, a few essential dimensions would make life easier. The photos show pistons with a noticeably greater axial dimension than the engravings do, which obviously reflects on the cylinder length. 

Steamer, on reflection I'm sure you're right, and may well turn up some gold. Thanks, and enjoy your truck!
Title: Re: SS Xantho John Penn trunk engine
Post by: PatJ on January 17, 2014, 04:40:03 PM
When I first saw Rich's Monitor, I was really scratching my head about what was happening inside the engine.

I ignored the engine for about a year, and then curiousity got the best of me, and I had to figure out what was in there.

I started studying trunk engines, and found sections of a few.
I will try and find those and post them here.

Trunk engines vary in that you may have a single trunk or dual trunks on a single piston.

The Monitor engine seems to be somewhat unique in that it combines two single cylinders into a common cylinder with a cylinder head installed inside the engine at mid bore.  This creates a very compact two cylinder engine, with the drawback being that some rather cumberson levers are required to get the power from the ends of the cylinders back to the crankshaft.

But generally, I found almost nothing about how the Monitor worked.
I finally found a section of the engine on some obscure website, and then was able to work out the geometry for a working engine, and make the simulation for the Monadnock engine.

I was surprised that the Xantho engine had two trunks on each piston, since you could operate the engine with one trunk only, which is generally how most steam engines operate (with a piston connected to a rod, and the rod is on one side of the piston only).
I have seen some German engines and others that had the piston rod extended through the top cylinder head and into a guide, but generally that was not used on the majority of engines I have seen.

When it comes to design, I am new school; ie: I use solidworks for engine design, and find it to be an invaluable tool if used correctly.
When it comes to materials and construction, I am very old school, and I never use any material or fastener that would not have been used on the original engine.
So that means no cap head screws, no loctite, no modern materials like teflon or o-rings, and generally studs with nuts, or bolts, but the nuts and bolts have to have the same profile as the old ones, which is generally a taller head or nut.

And I use gray cast iron, and cast the engines myself, generally from hand made wood patterns, but I have used 3D prints for patterns in some cases.
I prefer a wood pattern most of the time unless the shape has a lot of compound curves in it, and wood is much cheaper than a good 3D print.
You have to be good at woodworking to make good wood patterns.

And for bearings, I like to pour babbitt.
I don't use modern bearings.

I make piston rings from cast iron.
Packing material is a rope like material and it does sometimes have some sort of teflon in it, but that is not necessary, but probably works a little better, and is undetectable.

My interest is in small workshop engines generally in the 1/2 hp range, designed to work under load continously and indefinitely.
Models don't interest me as much because they require a lot more skill to make, and are very tedious to detail with their small and intricate parts.

I greatly admire those who make models, but I don't have enough patience or skill to do a good job with them.
My determination for engine size is made by taking the smallest screw on the engine, and dropping it on the floor, letting it roll under the workbench.
If I can find it again easily, then the engine is the right size for me.

Below are some engravings I have.
I am not sure if all of them are trunk engines or not, but I will post what I have.
Title: Re: SS Xantho John Penn trunk engine
Post by: PatJ on January 17, 2014, 04:44:04 PM
A few more engravings.
Title: Re: SS Xantho John Penn trunk engine
Post by: PatJ on January 17, 2014, 04:44:38 PM
And a sketch I drew.
Title: Re: SS Xantho John Penn trunk engine
Post by: smfr on January 17, 2014, 05:06:53 PM
My determination for engine size is made by taking the smallest screw on the engine, and dropping it on the floor, letting it roll under the workbench.
If I can find it again easily, then the engine is the right size for me.

 :ROFL: I like that, Pat!

Some very intersting engines here, and thanks for doing the research and posting the pictures. I'm following along!

Simon
Title: Re: SS Xantho John Penn trunk engine
Post by: Pedro on January 17, 2014, 08:06:55 PM
I second smfr. interestingly, a few engines in those engravings are of the back-acting crosshead type, of which Maudslay supplied the other half of the Crimean gunboat order.
Re single trunk engines, they have two obvious design weaknesses. Firstly they are not guided well on full extension, which must cause them to rock a little, putting strain on the packing and sliding surfaces. I believe I saw somewhere a reference to this regarding Ericsson engines, but I'm not sure.
The other issue is uneven power pulses, which can induce unwanted torsional vibrations. I don't know if that is any more than  theoretical. Ericsson's design reduces this greatly.
Pat, I'm with you on fasteners and external appearance, and understand the argument for traditional materials. I'm undecided, on the subject, but leaning towards more modern internals depending on the likely use, which admittedly will be little.
Title: Re: SS Xantho John Penn trunk engine
Post by: PatJ on January 17, 2014, 10:08:16 PM
With a single trunk, and with a trunk that large, there would be a difference in pressure on the piston comparing the trunk side to the non-trunk side.

This may have been compensated for to some extent with the valve gear, but there would still be uneven power strokes on the in and out stroke most likely.

Probably not a big problem at low rpm.
Title: Re: SS Xantho John Penn trunk engine
Post by: tvoght on January 18, 2014, 01:01:27 AM
Regarding back-acting engines, the engine of the former gunboat USS Ranger is claimed to be the last in existence and is apparently on exhibit at the American Merchant Marine Museum in Kings Point, New York.

This page contains a link to a downloadable brochure with illustrations:

https://www.asme.org/about-asme/who-we-are/engineering-history/landmarks/112-tv-emery-rice-steam-engine (https://www.asme.org/about-asme/who-we-are/engineering-history/landmarks/112-tv-emery-rice-steam-engine)

--Tim
Title: Re: SS Xantho John Penn trunk engine
Post by: peatoluser on January 18, 2014, 01:24:22 AM
If you look at about the 4 min. mark on this youtube clip, there's a good selection of horizontal engines

q1JXl4bWQW4
you can recognize some of the ones in PatJ's engravings

...and come early march I hope to be in London, so I think I know where I'll be going for a visit!

peter
Title: Re: SS Xantho John Penn trunk engine
Post by: Pedro on January 18, 2014, 06:38:29 PM
That's a fine exhibition. Time I took another look at it too. When I last went some 20 years ago they had totally reorganised and lost the plot by trying to be "relevant". The entire manufacturing technology section had disappeared, the Industrial Revolution erased from history with the vacated space turned into a kid's play area.  I mentioned it to a long serving curator who shook his head sadly and mumbled something about new management.

 I've had a friendly reply from the WA museum saying the relevant person is away, but back in a few days. I'm still waiting for the Model Engineer with the Xantho article to arrive. Does copyright law allow me to post photos from it or will I get the forum in trouble?
Title: Re: SS Xantho John Penn trunk engine
Post by: PatJ on January 18, 2014, 07:06:55 PM
Here is my "get in the ballpark" layout for the engine, at 1/8" scale.

I drew the passages at the bottom of the cylinder, but be aware that you would only see those when looking down on the top of the engine, not in the side view I am showing.

Bore is 2.625", stroke is 1.5".

Due to the angularity of the rod, the piston is not quite at mid-stroke.
The dashed lines show the piston at TDC.

Peter-
Nice video.  Some terrific engines in that place.

Edit:
Sometimes the valve face has to be extended outward to align with the eccentrics.
Title: Re: SS Xantho John Penn trunk engine
Post by: Pedro on January 18, 2014, 11:52:31 PM
Very nice it is too! No way a criticism, looks like there's a typo (ID/OD) on the trunk dimensioning. I'm still hopeful for input from the museum, will let you know asap. Well in the ballpark there I'd say. Well done.
Title: Re: SS Xantho John Penn trunk engine
Post by: PatJ on January 19, 2014, 04:52:24 AM
Thanks Pedro-

Yes, you are correct, I did miss that dimension.
I laid out the bore dimension (in haste), and offset out from that in the wrong direct.
That sketch is an just an hours work, but the geometry appears to be correct for a functional engine, ie: everything has the correct clearances in all the extreme positions of piston and crank/rod travel.

You can transpose a few lines inward to correct the bore dimension.

Nice engine though.  I like it.

I was surprised to see the steam chest design that extended upward for the steam pipe in one of the engravings for another engine.
It appears that it was standard practice of the day for trunk and direct connected engines?

These engines are somewhat rare, and probably the class of engines I know the least about.

It would really be nice to get some plans from the museum, but I have only heard of one individual having success with that.
I think museum people are very protective of what they have, and sometimes to the detriment of the flow of technical information.
Museums should at least photograph the drawings they have and publish them, but I don't think they do that.

Pat J

Edit:
There are some striking similarities between the Xantho engine and the engine below.
If you moved the condenser? on the right from the engine below, it would appear to be almost exactly like the Xantho engine, with the excepting of the engine below using crossheads instead of trunks.
The wheel with the worm gear would be how the engine was reversed, or the link position changed.
And they actually got the link suspension point correct on the engine below, which is at the center of the link, slightly inward of the link centerline radius.

The engine below gives a good idea of the alignment between the steam chest/valve and the eccentrics.
And like the Xantho engine, the cylinders on the engine below appear to be cast as separate units and then bolted together.

I am guessing from how shallow the steam chest on the engine below is, that the valve was a balanced type, and the top of the valve rode against the steam chest cover?
Title: Re: SS Xantho John Penn trunk engine
Post by: Pedro on January 19, 2014, 09:51:51 AM
I'm no expert, but that steam chest design is common on the engravings that I've seen. It could be that considering the low pressures of the time (about 2 atm + vac) it was the most reliable steam tight connection. Though the Xantho engine is reported as designed for 90psi (elsewhere 60) they could have continued it out of habit. Being a small engine, the forces on it would be much lower than with some of the monsters they built.
The original print that I have from The Engineer 24 Dec 1897 p623 (graces guide has it online) appears to be from a later mid-sized engine, though that's just my judgment. The drawing clearly shows a leaf spring preloading the valve, so this one at least isn't balanced.
Another point of interest is that the steam passages are partly in the cylinder covers. This may have reflected difficulties with shifting cores,or just contemporary thinking on getting the steam in the right place behind the piston but whatever it's an elegant detail. though it looks like the Xantho was more orthodox.
There are 3 original prints, all off the same plate by the look of it, on UK ebay, either labelled "John Penn trunk engine" or just "Trunk engine" The resolution on the photos is quite good, and worth a look, though they are of quite a large engine I think. 
Re the museum, I'm hoping that they're not being jealous and just haven't been asked. Also policies can change in 20 years,  Drawings are potentially an IP asset though so I can perhaps understand their possible reluctance to publish on the net, but I'd be surprised if they refused more photos and a few vital statistics. I guess it depends on whether there's someone interested enough to help. Alex Kilpa at the museum has published a recent thesis on the boiler safety valve, so it's not as if the original crew are all retired and "no-one knows nuffin".
Title: Re: SS Xantho John Penn trunk engine
Post by: PatJ on January 19, 2014, 04:21:00 PM
Pedro-

That is some interesting information.

I found an engraving of a Penn trunk engine on the open internet, and I will post that in a minute.

"The Engineer" article is very interesting, although a bit misleading perhaps.
The article mentions that the crankshaft is counterbalanced, as is the valve.
More correctly, they should have said "the valve is balanced", as there is no counterbalance for the valve mass.

The leaf spring affair is actually the inside shape of the valve which helps turn the steam as it flows into the exhaust port.
You can clearly see that the valve is balanced (at least I can, do others see that?).

The recess in the cylinder heads is only at the ports, and this allows for a higher efficiency engine since you reduce the clearance space between the cylinder head and the piston at TDC which would otherwise have to be filled and emptied with every stroke, but adding no additional power to the piston.

And you can see that the piston over-rides the end of the cylinder, which was common practice to keep from wearing a ridge in the end of the clyinder bore.  Valves also over-rode their seats for the same reason.

And the article mentions 6 psi, which sounds more like the old style pressure levels.
I am more familiar with the modern "high speed" steam engines; ie: the ones that ran from 150-300 rpm at the higher pressures, perhaps 50-100 psi.

Apparently the trunk engine was the next step in steam engine evolution from the large oscillators used for the sidewheelers? (check me on that).

And the offset of the steam chest towards the head end of the cylinder is interesting.
Apparently the engine was made as compact as possible, and then the steam chest position adjusted for an asymetrical location to allow the eccentric arms and link to fit.
This arrangement makes for unequal passage lengths, which would affect the engine performance to a slight extent, and perhaps compensated by valve gear adjustment.

And the article mentions that the trunk and piston are cast as one unit, but at best only the trunk on one side and the piston could be cast as one unit.  You can clearly see the bolts holding one trunk to the piston and other trunk.
This allowed installation of the wrist pin, and also made for a convenient installation of the piston ring or rings.
Title: Re: SS Xantho John Penn trunk engine
Post by: Jasonb on January 19, 2014, 04:53:10 PM
I'd say there is a leaf spring holding the valve to the port face, there is certainly something with a shallow eliptical shape fixed to the valve chest cover. Its certainly not the curved cavity within the valve.

It would not be a leaf spring a swe imagine them on a car or truck, more just a thin brass shim with a curve to give some "spring" and just enough to hold the valve to the port. Probably fixed at one end and slotted at the other to allow it to get longer as it is flattened.

 The porting within the cylinder end covers would just be a small area scalloped out adjacent to where the port exiys the cylinder, much the same way as we mill or file out a small are aon models to get the same results.

I also don't think the piston over runs the cylinder, the only place that is look as if it may do is where the steam port is, the rest of th eway the bore is parallel as it all the way with no increase in dia towards the ends

For some ideas about sealing the trunk on a model it would be worth looking at Anthony Mounts "Bodmer's sliding cylinder" engine, as that has a central tube or trunk with fixed piston that moves withing the cylinder although in this case the trunk is fixed and the cylinder moves but sam esort of setup.

J
Title: Re: SS Xantho John Penn trunk engine
Post by: Pedro on January 20, 2014, 12:57:13 AM
   As I understand it, the origin of the trunk engine (and the back-acting engine) was due to the strict military requirement for a screw engine that remained below the water line, out of the direct line of shot.  As such, it had to be horizontal, and could not afford the space taken by a crosshead. Given the Admiralty specifications, there aren't many other solutions. They are reported as being mechanically problematic, to the extent that there was a "right" and "wrong" main direction of rotation; the power pulses were arranged so that con rod angularity pushed and pulled the piston upwards against gravity, because they found this reduced wear. (source Xantho project). These problems  would have made them unsuitable for merchantmen and it seems that they were rare outside warships; Xantho's was war surplus after all.

    Pat, I must disagree with you on a couple of points. My copy of "The Engineer" article is an original, and the spring is clearly visible.between the valve and the cylinder cover, with a fastener to the cover at one end, and a radiused skid at the other.
    Re pressure, the 6psi quoted was for the previous decade. There are too many references to the gunboat engines working at  90psi and 180 rpm  to be baseless and we must remember that they are famous for being the world's first high pressure ship engines and were cutting edge technology for the world's only industrial and Naval superpower. 

    Jason, how do I find out how Mr Mount did it? I do believe that trunk engines could perhaps be viable modern steamboat engines with up to date seal and rod guide technology.
Title: Re: SS Xantho John Penn trunk engine
Post by: PatJ on January 20, 2014, 10:36:21 AM
I believe it was common practice to have the piston over-run the bore slightly.

I know for sure the D-valves over-ran the seat.

The piston should not extend into the port area, this is documented in the book by Charles Porter; it caused piston slap and knocking.

I have looked at all the engravings I have, and the only spring I see is in the condenser.
I don't see a spring at the valve, just the valve up against the flat interior surface of the ribbed steam chest cover.
Maybe you have a better or different engraving than I do.

The trunk engine has other problems even if it is rotated correctly.
Some of the documentation mentions that the large trunk thermally conducts too much heat out of the cylinder.
The trunk engine was an early design, and inferior to the crosshead-type engine.  It would not be a good modern engine even if the seal problem could be overcome.

It is a very interesting engine type, but just as it obsoleted the oscillatiing engine, the crosshead type engine obsoleted the trunk engine, the high speed engine obsoleted the low speed engine, and the compound obsoleted everything previous to it.  It was just progression of knowledge and design experience.
Title: Re: SS Xantho John Penn trunk engine
Post by: Jasonb on January 20, 2014, 12:40:57 PM
Pat, this is from the 1897 Engineer


Red arrow shows that the piston overruns the port.

Blue arrows show that the rest of the way around the circumference there is no over run of the piston

Just inside the valve chest I can see the curve of the leaf spring and a fixing at one end sketched in green just above. I have also sketched what I think the valve spring looks like

Link to the engineer here (http://www.gracesguide.co.uk/images/1/10/Er18971224.pdf)
Title: Re: SS Xantho John Penn trunk engine
Post by: PatJ on January 20, 2014, 01:45:25 PM
Jason-

I see what you are saying about the lack of counterbore in the bore.
That is a bit odd, but it is as you say.

For a slow speed engine, I guess it is not significant.

The article mentions that the crank and valve are "counterbalance", and I assume that means the valve is balanced.
And so if the valve is balanced, then there is a hole in the top of the valve which keeps the top of the valve at nearly the exhaust pressure, and with a spring as you show, then steam would be admitted into the hole and out the exhaust at all times, so something does not add up with that.
Title: Re: SS Xantho John Penn trunk engine
Post by: peatoluser on January 20, 2014, 02:15:20 PM
I'm no expert and bearly understand valves, so feel free to correct this, but sometimes the valve linkages were counterbalanced. metallurgy was in it's infancy especialy for bearing surfaces, and sometimes a counterweight was fitted to try and alleviate wear. as here

http://www.digitalis.uni-koeln.de/Matschossd/matschossd_index.html   page 650

I know it's a side lever engine but it does show the principle, and I think that is what is going on here as well
http://collections.rmg.co.uk/collections/objects/68060.html

perhaps when the article refers to a counterbalanced valve , it's refering to something like that?

on the plan view in the engineer (also here in matschoss :- http://www.digitalis.uni-koeln.de/Matschossd/matschossd_index.html    page 710 )
there does seem to be two weights jutting out on the right hand end

yours

peter
Title: Re: SS Xantho John Penn trunk engine
Post by: PatJ on January 20, 2014, 02:25:30 PM
I am no steam expert either.
I make comparisions between what I see in the old engravings, and what I read in the old books, and try and connect the dots.

Steam engines underwent a tremendous development in a very short period of time.

Here is an engraving for a balanced valve.
Title: Re: SS Xantho John Penn trunk engine
Post by: Pedro on January 20, 2014, 04:04:19 PM
A couple more titbits. Xantho project states that the gunboat engines needed so much maintenance that there was if possible a fully equipped engineering support vessel accompanying them on deployment. One has to wonder if that experience was what persuaded the Admiralty to abandon the below water line rule and thus enable the introduction of crosshead engines.

Also, the 1/6 scale model at the museum was completed before the engine was dismantled and thus the internal design could only have been guesswork, so unless there's a more recent model out there, no one has yet made a dimensionally accurate one.

Pat, I wholeheartedly agree with you about reduced thermal efficiency, but efficiency isn't a huge consideration for small steamboat engines. I strongly feel that the major weakness of the design is the reliance on the packing as a bearing to take the side thrust from the con rod, and it may well be possible to fix it with modern bearing materials. Relying on direction of rotation to save wear is at best a bodge and highlights inadequate design
If it could be fixed, it would make an interestingly different  machine. 
Title: Re: SS Xantho John Penn trunk engine
Post by: Jasonb on January 20, 2014, 04:20:10 PM
Pat, as Peter says the valves were counter balanced on some engines not pressure balanced, if you look at this one that you posted you can see that the linkage to the expansion link/ die block has a counter balance weight in much the same way as a crankshaft is counter balanced. I suspect there is something similar on teh Penn engine.


Title: Re: SS Xantho John Penn trunk engine
Post by: PatJ on January 20, 2014, 05:31:39 PM
Pedro-

I have learned to never say never, since I have seem people suggest improbable solutions several times in the past, then they actually worked well.

There is always the possiblility of solving the sealing issue, but I also recall the Wankel car engine which was suppose to replace all other auto engines.
The Wankel did run very well, but its achilies heel was the seals, and that was never solved.

Edit:
I did see some special gland nut seals on and engine, but I forget which engine, and it seems like they were metalic rings perhaps sanwiched between regular packing.  But the article said that it solved all of the piston rod sealing issues.

I find it ironic that the first known engine (Hero's engine) is still the steam engine that is in common use around the world.
The uniflo had great promise and very good efficiency, but it came too late in the game.

Jason-

I see the weight on the valve gear to balance it out, and that may indeed be what the author is referring to, but the D-valve in the engraving looks a lot like the balanced valves I have seen, since it extends up to the face of the steam chest cover, and the shapes on either side of the valve could be seals.
I will try to research when the balanced D-valve came about, and perhaps that could rule it out as a balanced D-valve.

I made a 3D model of a Stanley 20 hp engine from the drawings from the Stanley museum, and noticed several things that I later found mentioned in the old books such as the valve often traveling only 80% of the port opening (sometimes the valve overtraveled in some engines), and the over-run of the moving parts such as the pistons, crossheads, valves, etc.  Generally anything that moved was designed to over-run if possible to prevent ridge buildups.
A ridge would destroy an engine as the bearings wore.

The Stanley also had roller bearings on the large end of the rods.  I had heard that these were ball bearings, but they were actually roller bearings.

I wonder if the museum could clear up any of these points?
Surely they must know.
Title: Re: SS Xantho John Penn trunk engine
Post by: Stuart on January 20, 2014, 05:47:02 PM
The counter balance on the lift arm ,springs on a loco was to reduce the effort required to lift the dead weight go the gear which in a 12 inch to the foot model would be large



Stuart
Title: Re: SS Xantho John Penn trunk engine
Post by: PatJ on January 20, 2014, 07:12:24 PM
I think the information says "counterbalance on the crankshaft and valve".

But a balanced valve is very different from a counterbalance on the valve gear, and it does not say "counterbalanced valve gear".

Hopefully Pedro can get some information out of the museum folks.

Rich Carlstedt said that the museum folks who had the Monitor were not necessarily up on their steam engines, and they reassembled the Monitor engine with some items in the wrong configuration, which Rich said he pointed out to them.
If the guys who made the drawings are still around, or if they knew what they were looking at when they drew the engine, then the museum should have some answers.

Pat J
Title: Re: SS Xantho John Penn trunk engine
Post by: Jasonb on January 20, 2014, 07:58:04 PM
As it says Crankshaft and Valve in the same sentence I would assume its weight balance as what else could it be on the crankshaft as that is not subject to steam pressure.

J
Title: Re: SS Xantho John Penn trunk engine
Post by: Pedro on January 20, 2014, 08:32:56 PM
It's an art in itself to write a technical article in language that is entirely unambiguous. My limited experience of technical journalists is that they can gloriously mangle the details of an interview and maybe that's what's happened here.
I'm new to valve gears but isn't the counterweight in the engraving for the Stephenson's link?
I've seen no evidence for that sort of counterweight on the Xantho engine itself. If there was one it would have been on the cross shaft running through eyes on the top of the frames.
The facebook side elevation photo on the first page of the thread shows what looks like a crosshead guide for the valve rod, which is missing on the engravings that we've seen so far of larger and slower engines. This would give useful support at the high speeds these motors ran.     
Title: Re: SS Xantho John Penn trunk engine
Post by: PatJ on January 20, 2014, 11:47:05 PM
I will have to look at the engravings and read the description again.
I read it rather hastily the other day.

I have noticed that not all technical books are necessarily correct on all points.
The knowledge of how steam engines workd was an evolving thing, and some books don't describe the suspension point of the link correctly for symmetrical valve operation, or even seem to be aware of such things, and just recommend suspending the link from the end, which is noted in some later literature as causing a lot of assemmetry in the valve movement throughout the range of the link motion.

For marine engines, this may not have been a problem since they generally ran in full link (correct term?), but I think the Xantos article mentions that link wear was a problem for this engine, and special inserts were used to accomodate the wear, but what this could say is that the suspension point was not laid out to minimize link slip.

Unfortunately some of the better steam books were heavy on the math, which can make for some daunting reading for some who don't have that background, or even for someone who does.

I have a book list, and a collection of PDF books.
I forget how many, perhaps 100 or so that I collected in the days when the PDF's could be downloaded for free.
I will post the list here somewhere if there is a place.
Edit: Posted here:
http://www.modelenginemaker.com/index.php/topic,3070.msg53149/topicseen.html#new

These are books in the public domain, and so they can be shared if someone has a method to transfer large files such as an FTP site.

Pat J
Title: Re: SS Xantho John Penn trunk engine
Post by: peatoluser on January 21, 2014, 10:15:45 AM
Thanks for the illustration of the balanced valve Pat, It explains the idea very clearly. like you I try to piece things together from reading the old books and looking at the illustrations, hopeing that there's no ytpo error!

my appologies about the matschoss links . I thought they would take you directly to the relevent sections.  you need to click 'erster band' then the page section.

given the stated speed of the engine and position of the valve on the side, I can see the reason for a balance weight as in your illustration that Jason pointed out - it looks to me as if it is trying to take some of the weight of the valve rod.

but also given the stated pressure, it would make sense to 'pressure balance' the valve. maybe both methods where used?

wearing out of bearing surfaces was a real problem, so counterweights were often used.

this was especially true of propellor shaft bearings.

HMS Royal Albert had to be run ashore to prevent her from sinking, because so much water was coming in through her stern tube, and on HMS Malacca it was recorded that the brass of the stern tube was wearing away at the rate of 5lb per day.

and perhaps to show that I've not entirely gone off topic, it was a certain John Penn in 1855 who largely solved the problem by using lignum vitae bearings.

Pedro, isn't there a full size replica of a John Penn trunk engine not far from you in 'Oil Fuel Hulk C77? (perhaps better known as HMS Warrior!)

yours

peter
Title: Re: SS Xantho John Penn trunk engine
Post by: PatJ on January 21, 2014, 06:41:54 PM
Peter-

I think the weight on the valve linkage is to balance the weight of the link and valve rods?

I am finding that there is a danger in talking in generalities about steam engines, since they evolved so dramatically in a short period of time.

Charles Porter mentions observing various engines at the London International Exhibition in 1862, where he displayed the first moder high-speed steam engine, but generally a slow speed steam engine does not have the rigourous design requirements that a high speed engine would have.
Almost any configuration can be made to work with a low speed engine, but that does not mean it is necessarily good design practice.

Porter noted that some engines were poorly designed with low efficiency, and furthermore, none of the engines displayed there were suitable for high speed operation (150-300 rpm) except his.  Porter also designed and demonstrated the first high speed governor with his engine at this exhibition.

The head of the Exhibition, Daniel Clark, forbid Porter from running his engine at a speed greater than 100 rpm, and even that speed was considered excessive.
Luckily Porter ignored Clark and ran his engine at 150 rpm, and demonstrated the first high speed steam engine.
When Porter first started his engine, it was widely though that the engine would fly into pieces.
Clark timed the engine with his watch, as a very nervous Porter watched, and after measuring 150 rpm, Clark turned to Porter and said "Mr. Porter, if you engine will run that smoothly, you can run it at any speed you want".

But there were a number of differences in the Porter engine, such as a very rigid frame, and shortened and enlarged crank pin, careful balancing, and other subtle but highly significant differneces, such as the piston not protruding into the port area.

So when you look in the old books, what you see depends on the era of the design, and the state of the art at that time.
Another thing to consider is that the illustrator (the guy making the engraving) did not necessarily understand engine design, and the engravings were not necessarily made to show the finer details of the engine, but rather an overall view of the appearance and workings of the engine.

Here is an engraving from Audel's, which shows a section of a relatively modern steam engine cylinder.
You can see the counterbore in each end of the cylinder, and you can also see that not only does the piston over-run the end of the cylinder, but more importantly the ring over-rides the bore, for it is the ring that actually does most of the wear on the cylinder.
And the piston does not protrude significantly into the passage area.

You can see the valve over-rides the valve seat in the engraving below also, and note that the cylinder heads are recessed inwards to minimize clearance and improve efficiency.

Studying the original drawings of a Dake engine show the same over-riding of the pistons against the back of the cylinder, with a groove used to accomplish this.

Pat J
Title: Re: SS Xantho John Penn trunk engine
Post by: Pedro on January 21, 2014, 09:59:52 PM
Hellsbells Pat, you are a mine of information. Thanks for the books too. Those clearances make so much sense (in hindsight) for a long life engine. What decade did that come from? Wikipedia says balanced valves were common in the US and rare in the UK, where piston valves were preferred. Trouble with a worn out piston valve I guess is it can't be easily fixed by a scraper hand. Still waiting for the ME to arrive and the curator to come off leave. 

Currently brooding on machining the cylinders. I think one end cover is cast in like in the engravings we've seen, so might need a separate valve plate to get the steam ports in. There are some awkward cast reinforcement webs too. Do you know if the cylinders would have been lagged, and if so with what? Lagging could cover a lot of sins......
     
Peter, I'd like to see Warrior, but considering her engine's a modern dummy, rightly or wrongly I feel I wouldn't learn much. Also her engine was of the old slow low pressure type, of which there's more info available. The Science museum has a model of HMS Minotaur's engine which had 112" bore, 52" stroke!
Title: Re: SS Xantho John Penn trunk engine
Post by: PatJ on January 22, 2014, 03:53:33 AM
Pedro-

When it comes to steam engines, yes, I admit, I am an obsessive compulsive.
I went through a period of research a few years back, and found a lot of steam engine information.

More recently I have focused on casting iron, and making workshop-type engines (sort of oversized models).

The restoration photos are low resolution but I think I can see heads on both sides of the engine, but at any rate that is how I would build it.
Trying to make the head built-in would be tricky, not impossible, but tricky.

Any way you make it will be interesting, and without museum plans, there is no way to be certain of exactly how it was.

Often times people free-lance engine designs to make an approximation of an engine, sometimes with some loss of accuracy, but with the benefit of having a reasonable design and build time and something that is not too complex to build.

I can see that the cylinders were cast separately, and then bolted together.
I would guess that the cylinders had lagging, that was somewhat typical of the old engines.
Generally strips of wood with insulation beneath, or just wood for the lagging; not critical for a model.

Are you aiming for a museum grade engine, or just looking for something to build?
You can go as wild as you want on detail, if you have the time and patience.

If you get the museum drawings, I would like to put the engine in a 3D model if that is possible to exchange that info.

Many choices to make.
I will be watching with interest.
Good luck.

Pat J


Title: Re: SS Xantho John Penn trunk engine
Post by: Jasonb on January 22, 2014, 07:44:01 AM
Yes it does look like the front cover is integral to the cylinder in the engineer engraving makes it a bit harder but not impossible. How did you intend to do the cylinders, machined from solid or fabricated?

The radial webs could easily be soldered into some shallow milled slots to locate them or if the engine is not going to run much on steam could be bonded on.

There is not much room for lagging but could well have been timber under a thin russian iron cladding sheet

J
Title: Re: SS Xantho John Penn trunk engine
Post by: Pedro on January 23, 2014, 01:59:00 AM
I'm fairly confident about the front cover being integral.  The Graces guide photo shows none of the cover bolts that you'd expect. I feel at present that redesigning it would cause more harm than good. On reflection, those webs and lugs are less of a problem than I first thought, but will still require a lot of care and some accurate sums. 

 Building something like this is outside my comfort zone so I'm really not sure how far to take it. My philosophy I suppose is to at least consider copying it as closely as my ability and patience allows and play to my strengths, then work on the weaknesses. If you build the bare bones as well as possible, at least you won't be kicking yourself later in the build.  I'm more used to carving from solid rather than fabrication, so that at least will be my starting point.  If I find that I'm really not up to the job, then is the time to simplify but  whatever happens I'm not prepared to compromise on the dimensions and the overall look of it, even though my primary goal is an elegant and smooth engine.
 
Of course if we can't get the drawings, a freelance element will be essential anyway.

 
Title: Re: SS Xantho John Penn trunk engine
Post by: PatJ on January 23, 2014, 02:20:58 AM
Pedro-

Look up some of JasonB's work if you are not already familiar with it.
He does a really good job of silver soldering up the bits into something that really looks like a casting, and like the original engine.

I hope you are good at silver soldering.

Pat J
Title: Re: SS Xantho John Penn trunk engine
Post by: Jasonb on January 23, 2014, 07:38:03 AM
You want webs

http://www.modelenginemaker.com/index.php/topic,705.msg10289.html#msg10289

J

PS spent too long in the workshop last night, will sort out that info tonight.
Title: Re: SS Xantho John Penn trunk engine
Post by: Pedro on January 24, 2014, 02:36:17 PM
Very impressive it is too, Jason and many thanks for the Bodmer info. That is a fascinating engine also, but I wouldn't be surprised if it had similar seal problems. The gland on the Xantho is very much longer, which affords greater options. Pat's Audel engine clearly shows a bearing bush, which has to be part of a better solution.
    I've only soldered small assemblies to date, so concerns about getting it right and my experience with "hogging it out" have led me in the barstock direction. I realize now that I was wrong, particularly in this case, with the integral cover, webs and lugs making it impractical, and fabrication has to be the way. (gulp!) This is why I was wondering about lagging, since an all in one Russian iron cover would hide things that individually wooded ones don't.
I've also made myself a victim of "mission creep", obsessing on details and while it's right to examine as many aspects as possible, at some stage sensible decisions must be made.

I have the ME now, and can email the article. There isn't a lot of new info other than one small photo of the finished model, which is a very good job, especially considering the original was only partly deconcreted and still in the tank when the model was finished, though it may well have been updated in the last 20 years.  FYI, Bob Burgess' trunks were 8", crankpins 3/4" and mains 7/8" at 1/6 scale. He also wooded the cylinders, but I'm hoping that was an inaccuracy. Maybe the museum can help.

 It's possible that while they measured everything, they never did proper engineering drawings. just sketches. After all, why  go to the expense as long as the info is clear. I''ll find out soon.

Title: Re: SS Xantho John Penn trunk engine
Post by: Pedro on January 26, 2014, 11:12:43 AM
This is interesting:  http://search.informit.com.au/documentSummary;dn=741576178654316;res=IELENG

It's a preliminary report on recording the engine components with 3d laser scanning with a view to publishing on the net for academics and modellers. Being dated Nov 2013 it looks like it's work in progress, so at a guess will take some time.
I'll find out from the curator when he returns. This paper looks like it is restricted to academics and students so I could only read the precis.
Title: Re: SS Xantho John Penn trunk engine
Post by: Pedro on February 01, 2014, 02:33:24 AM
I've had a very pleasant reply from Mack McCarthy who is the project leader at the museum. Unfortunately, while they intend to publish plans, there are none available at present. I've asked if they could take a few basic measurements and am waiting for a reply. While the photos are good enough to make a start, I'd be much happier with a few hard numbers.
 
I'd like to offer my deepest thanks for the interest and help that I have received so far, and shall keep you all posted.

Ps Pat, of course I'll cooperate. Sorry I didn't mention it before.
Title: Re: SS Xantho John Penn trunk engine
Post by: PatJ on February 01, 2014, 03:35:46 AM
Pedro-

I have a long list of engine projects going, so no big deal if you can or cannot come up with some significant information.

I would not overlook the fact that you should be able to get very close to the original geometry of the engine just by looking at the photos.

I have designed several engines just from a few photographs.
It is just a matter of maintaining the proper proportions, and laying out the geometry to allow for free travel of the moving parts.

Studying the old engravings helps a lot too.

Rich Carlstedt has quite a few photos out there on the net for his Monitor trunk engine, and you can get a feel for how he handled the internals of the engine by looking at those photos.
http://www.smokstak.com/forum/showthread.php?t=37639

Pat J

Edit:
I found the photo below on the open web and can't credit the souce since the photo is clipped off.
Title: Re: SS Xantho John Penn trunk engine
Post by: Pedro on February 09, 2014, 01:11:02 AM
I haven't got much to report other than I had a very positive response from Dr McCarthy in which he agreed to add dimensions to my sketches, so not to waste his and the museum's time I've been learning Draftsight, which I'm enjoying very much. I don't use computers much and a new Linux os so there's a bit more to learn than for many. Did the first few in 1/10 scale then had the "Doh! moment".

 I think I've pretty much mined the net out of the important info. Hopefully the museum will send a few pics of the blind areas, but not vital. As Pat said, there's plenty of info already for a good representation, but it's always better to have a little too much info than just too little.
Title: Re: SS Xantho John Penn trunk engine
Post by: PatJ on February 13, 2014, 08:45:23 PM
As I understand it, the working model of the Xanthos engine was build without knowing the exact inner details of the full sized engine, and yet the model still functions well.
But exact details are the icing on the cake, and I love icing, perhaps as much or more as the cake.

I wrote up a Draftsight tutorial a while back.
Not sure if I still know where it is, but I will try and dig it out, for what it is worth.
It is just a summary of how I have used 2D over the years, with an emphasis on using the Drafsight program.

Pat J
Title: Re: SS Xantho John Penn trunk engine
Post by: Pedro on February 15, 2014, 01:43:50 AM
I've found a draftsight thread of yours on HMEM- it's very instructive. I've sketched a cylinder, a frame, a cylinder cover and the trunk/piston, using the 21" bore/11" trunk as datum scales. They're nearly good enough to send when I've figured out how to print to file, since the tick box won't open for me. I've included a table of the requested dimensions on the drawings so the measurer only has to fill out the blanks and not have to refer to another sheet of paper. (Dimension A, dimension B etc though my guessed sizes also show. I'm trying to make it as easy and readable as possible. There may be an issue of my credibility with the museum, so I'm putting a lot of thought into it.
The blind areas so far are the cylinder contours on the steam chest face, and the main bearing detail. It's hard to make out whether the mains were of the square brass block type, or turned and keyed cylinders. I'm hoping Mack McCarthy can tell me.
If I get enough info, it would be polite (and fun!) to give the museum detailed drawings as a thank you. Whether I'm up to it remains to be seen, but so far I'm confident.
   
Title: Re: SS Xantho John Penn trunk engine
Post by: PatJ on February 15, 2014, 02:13:54 AM
I am sorry you had to go off-site to get the Draftsight stuff.
I started to load it here yesterday, but did not have time to do much with it.

Good to see you putting the effort into discovering the finer details of the engine, and drawing it in CAD.
Very nice.

Pat J
Title: Re: SS Xantho John Penn trunk engine
Post by: Pedro on February 17, 2014, 01:40:03 AM
Thanks for the encouragement! I was going to add my piece to your 2D Cad thread but was too busy until it was too late. I can't deny that a tutorial dedicated to model engines would be of great help, since there's much in the programs that is irrelevant. There is also the issue of glossary: it can be difficult to follow the simplest instructions if one doesn't understand the terms.
That said, I do take pride in not asking for help unless absolutely necessary.  The Draftsight manuals are quite good, and your advice on other forums is first class, though I'm still trying to absorb it. 
Here's my first effort, assuming I can get it to post. I'm very keen to make it as easy as possible for Dr McCarthy and his staff, so any comments would be appreciated.
Title: Re: SS Xantho John Penn trunk engine
Post by: PatJ on February 17, 2014, 02:25:15 AM
Pedro-

That is great looking CAD work.
Hats off to you for picking it up so quickly.

I will look at it and see if anything jumps out at me.

Pat J
Title: Re: SS Xantho John Penn trunk engine
Post by: Pedro on February 17, 2014, 04:09:30 PM
Thank you. It's really not too difficult, particularly with the manuals and online help.just needs concentration. Being a complete computer novice (cut and paste was an adventure only a few weeks ago)  I'd recommend Draftsight to anyone, though either it's me (likely) or the Linux version is a bit buggy. A1 for a freebie, though.
Here's the frame and piston. Just repeating to new followers of the thread that these are just information gathering sketches, not drawings, so lacking in detail.

Ps Just saw I missed a dimension- will correct.
Title: Re: SS Xantho John Penn trunk engine
Post by: Tempus3966 on March 19, 2014, 01:06:41 PM
Hi,

I'm currently attempting to create a complete 3D scan of the trunk engine from SS Xantho.  The work is on-going, but should be completed over the next couple of months.  I've attached a few low-resolution images for reference.  Feel free to contact me should you require any additional information.  Also, one of the conservators, Alex Kilpa, recently completed his masters degree which focused on the  reconstruction and analysis of the safety valve from Xantho.  His dissertation can be downloaded free of charge from www.maawa.net/uploads/Xantho_Thesis_Published_version.pdf

Kevin Edwards

(https://fbcdn-sphotos-c-a.akamaihd.net/hphotos-ak-frc3/t31.0-8/1658701_10202332407745569_540491051_o.jpg)
(https://scontent-b-lax.xx.fbcdn.net/hphotos-frc3/l/t31.0-8/1891563_10202332408825596_1670581072_o.jpg)
(https://fbcdn-sphotos-a-a.akamaihd.net/hphotos-ak-prn1/t31.0-8/77531_10202332408105578_1544788515_o.jpg)
Title: Re: SS Xantho John Penn trunk engine
Post by: Tempus3966 on March 19, 2014, 01:24:19 PM
Here's a better example:


(https://fbcdn-sphotos-a-a.akamaihd.net/hphotos-ak-prn2/t1.0-9/1236525_10202579898252677_1243490007_n.jpg)

Kevin
Title: Re: SS Xantho John Penn trunk engine
Post by: tvoght on March 19, 2014, 02:36:33 PM
Kevin,

That's very interesting and would surely be a great help to anyone wanting to model the engine.

I'd be interested in hearing how the scanning was/is done.

--Tim
Title: Re: SS Xantho John Penn trunk engine
Post by: Tempus3966 on March 19, 2014, 03:35:18 PM
Hi Tim,

The engine and some of the larger components (such as the safety valve, isolating valve, cylinders and conn rods) have been scanned using an Artec Eva scanner.  The smaller components are being scanned using a NextEngine 2020i triangulation laser scanner.  I recently published a paper on the latter in the Bulletin of the Australian Institute for Maritime Archaeology.  I can send you a copy if you like.

Best,

Kevin

Title: Re: SS Xantho John Penn trunk engine
Post by: Pedro on March 20, 2014, 09:52:38 PM
Those scans are just gorgeous! I owe the forum a progress report. Dr McCarthy has been extremely helpful and I think has decided that the time is ripe to "do a job" on the engine. I haven't been posting my drawings yet because I'm nervous about the museum's IPR and besides they're still incomplete so it would only be blowing my own trumpet. It's been a little frustrating since I'm keen to start cutting metal but it won't be long now particularly with Kevin's scans. These are exciting times.
Title: Re: SS Xantho John Penn trunk engine
Post by: USSMonitorLab on March 24, 2014, 07:17:45 PM
Hi All, we've been following your thread on the SS Xantho engine and noticed you mentioned the USS Monitor. Rich Carlstedt is a wonderful source, given his beautiful little engine, and is a frequent friend/visitor and sometime advisor to us here at the USS Monitor Center, part of The Mariners' Museum and Park. We also happen to have a great model of the engine here that was built by our incomparable former volunteer Bernie Denny before the actual object was retrieved from the wreck site.  He was also a friend to Rich and they had a great correspondence about the engine for several years.
If you have particular questions about the Monitor at any point, please do contact us here in the Batten Conservation Complex. We will be happy to help however we can. We are immersed in the conservation, archaeology, design and alterations of this ship daily. You can see what we've been doing over the years at  http://www.marinersmuseum.org/blogs/ussmonitorcenter/
Please email us directly at: conservation@marinersmuseum.org and we wish you the best of luck with the Xantho engine!