My new steam engine project

[bogstandard]

Hi All,
I am building a new engine, not for you this time but one for me that is going to power an engineering educational display model. This won't be a warts and all build like the last one, but a series of photos taken as I build the engine, all leading up to hopefully a video of it running.
I am about two weeks into the build, so piccies will be thick and fast to begin with, then when I have caught up, as the engine proceeds.
Again, my usual practice of using scrap and junk materials, plus leftover screws and nuts (a mixture of thread sizes, metric and imperial, used to suit the job), plus a few home made ones as well. The cost up to now is less than £5.
I have taken a standard generic plan (of US origin) of a mine engine (#29 in the plans for download section that Eddie submitted), shown below, and converting it to suit my needs, plus make it look more 'Victorian'.
As with my last build I welcome your comments, hints and tips, plus if you want to know something, don't be afraid to ask.

John

[bogstandard]

Right, lets get this thing underway.
Bandit and Vinnie have sorted some piccies out for me to show you how far we have got. Bandit has taken to living in the workshop now and has moved his bed in.
In the first shot I have already made the basic cylinder, this being the hardest bit, I thought I would get it over and done with.
I knocked up the flywheel out of a bit of ali plate but wasn't really happy with it, more on this to follow.
All the rough bits of plate have been cut and some machined to size.
The columns are the first deviation from plan (lollipop sticks as Derek calls them), love 'em or hate 'em, they are here to stay. My engine, I puts wot I want on it.
Pic 2 shows a back view. The second deviation is that I am going to put as many ball races in as possible, this engine is going to be made to run on compressed air (although it will run on steam) and will be running for up to 8 hours at a time while on display. The two bottom support plates were bonded together and machined as one to simulate a base casting.
The third picture is a little further along, with support brackets made and plate all screwed together. You will notice in the background a bit of ali plate with circles on it. I am just experimenting with a couple of milling cutters that came into my possession and I will be using this later.
For pic 4 later is now here, as I said earlier, I didn't like the ali flywheel, well I had a bit of 1/2" thick brass plate, so I decided to go to town and made one out of it. The experimental cutter was used to simulate a riveted rim. The brass flywheel took about 7 hours to make because I kept getting dimensional overflow in my brain trying to remember where I was up to on the rotary table when profiling the spokes, one mistake and it was a do it again job.
Number five is showing a close up of the simulated 'barley twist' columns. They are a double helix, concave cut at 2 1/2 threads per inch. Mounted in a bit of profiled hex bar to give them a base. They really need to be 1TPI but my lathe won't reach that far. I tried a four helix thread, but at this scale it looked like chewed up brass rod.
The last picture shows the bearings squeezed into the areas that needed them the most. The eccentric was the worst, very tight, and a lot of maths by Bandit to make sure it would all work as required. I am deviating here from the plan on this bit, the plans show the eccentric rod sticking out the side, I am taking it straight up and thru a bellcrank to its original position. If possible, if I can squeeze it into the limited space on the cylinder platform, I am going to try and put a reverse linkage in, if I can achieve this, it will double the amount of items I can power with it, by using one way drives, two separate areas can be driven at different times.

Now lets have some comments and tips.

John

[derekwarner_decoy]

Yes PD's .......that's what I called them ... (lollipop sticks as Derek calls them), BLOODY terrible...but me as your humble OZ member has secured the Patient rights to Bogstandards next project here on PD's :nah

John & I have been  :gather this for a day or two & I certainly look forward to the lessons & piccies as DISHED out :news

[bogstandard]

Now that at least a few people are looking, but not many replies, I will show you a little bit more. With the engine in the final colours but not final finish.
I would just like to say that if you are into model engineering, or just starting, the Elmer Verburg plans that are in the downloads section are a good basic set of engines, with types to suit everyone, and as I am showing, they can be changed about without compromising the running qualities. If you just want to display them on air, most of the bits can be made of aluminium, but if you want to run on steam, the cylinder and its associated valvegear really needs to be made of brass, bronze or cast iron.
Anyway, back to the pictures.
The first one is showing the mod I did to the eccentric and flywheel. The eccentric is normally grub screwed to the crankshaft, but in this instance I have decided to drive it from the back of the flywheel for two reasons. The first is that I can time the valves more accurately by slackening the flywheel screws and using the larger radius of the flywheel to get finer tuning. The other reason is that because I put a ball race in the eccentric, there was no room for a grub screw fixing.
The next three pics are just views of the basically finished bottom end.

This is now up to date, and I am now concentrating on the cylinder, leaving the valve gear until last as I want to design a manual reversing system for that.

Any questions or comments on what you have seen so far?

John

[crash93]

Yes the flywheel is much better than ally , the reason why you think not many are watching may be Like me they get posts for steam sent to them as mail , soit would not show up as being read would it.? or am I wrong. but great build as usual and thanks  peter

[bogstandard]

Hi Peter,
I don't know if what you say is happening, I don't know about things like that.
I know you are a bit of a machinist so you might be interested in an American site that hasn't been online for very long, and is geared towards these types of barstock engines.

http://freeforums4u.com/index.php?mforum=homemodelengine

Very few UK members at the moment (3 I think)

John

[crash93]

Yes John you mentioned it to me about it the other week and I do look on it two or three times a week , But its all beyond my bodging skills so its not worth me registering .the only engine I have built was a reeves twin with a bit of help and it needed about 100 psi to make it run , I found out what was up the steam ports where half way down the bores,...I will repair it one day, and the rest I do is just hammers and files but iI enjoy looking at skills at work thats why I follow your builds.

Peter

[sandy_ACS]

   :yeah

Hi Pd's,

Yes I am still in this world.

John...... magnificent work as usual..... glad to see you are using the standard colours 'Black' and 'Brass'....  :music

The third picture is a little further along, with support brackets made and plate all screwed together. You will notice in the background a bit of ali plate with circles on it. I am just experimenting with a couple of milling cutters that came into my possession and I will be using this later.
For pic 4 later is now here, as I said earlier, I didn't like the ali flywheel, well I had a bit of 1/2" thick brass plate, so I decided to go to town and made one out of it. The experimental cutter was used to simulate a riveted rim. The brass flywheel took about 7 hours to make because I kept getting dimensional overflow in my brain trying to remember where I was up to on the rotary table when profiling the spokes, one mistake and it was a do it again job.
Number five is showing a close up of the simulated 'barley twist' columns. They are a double helix, concave cut at 2 1/2 threads per inch. Mounted in a bit of profiled hex bar to give them a base. They really need to be 1TPI but my lathe won't reach that far. I tried a four helix thread, but at this scale it looked like chewed up brass rod.
The last picture shows the bearings squeezed into the areas that needed them the most. The eccentric was the worst, very tight, and a lot of maths by Bandit to make sure it would all work as required. I am deviating here from the plan on this bit, the plans show the eccentric rod sticking out the side, I am taking it straight up and thru a bellcrank to its original position. If possible, if I can squeeze it into the limited space on the cylinder platform, I am going to try and put a reverse linkage in, if I can achieve this, it will double the amount of items I can power with it, by using one way drives, two separate areas can be driven at different times.

So it looks like you have got hold of a couple of 'Rotabroach' hollow cutters, or at least something similar, judging by the circular cuts on the test piece and the flywheel..... your brain must really hurt after doing that one on your 'Manual' rotary table.

I take your point with lathes not being able to go down to 1tpi, at least not very many of them can.... the main problem is the huge strain placed on the standard gear drive of the headstock when doing low tpi cuts...... effectively the leadscrew has to be geared up from the spindle.....however, if you disconnect the normal drive chain and arrange to turn the leadscrew, either by hand, or via some external means other than the lathe motor, and gear the spindle directly to the leadscrew (an 8tpi leadscrew would need to be 8:1 with the spindle for 1tpi) then this places the load in the correct sense, i.e. the spindle is now geared down from the leadscrew, and is quite easy to turn and cutting low tpi forms can be quite easily achieved.

You mentioned putting an extra bell crank between the eccentric strap and the valve.... remember this will reverse the valve motion and the other thing to keep in mind is the angular difference between the two existing valve operating arms.... this angle is critical in that it equalises the positional error that occurs in the standard valve mechanism brought about by angularity  of the eccentric rod/strap.

As for reversing...... why not go for a slip eccentric.... you already have half the requirements by having a pin drive for the eccentric.

If the valve has LAP and possibly LEAD, which would mean the eccentric was at something other than 90 degrees to the crankpin, then there is no mechanism that will give correct valve timing other than moving the eccentric.... unless you wish to use a totaly different valve gear, such as
Hackworth, Joy or some sort of link mechanism, such as Stephensons.

I will be interested to see what you had in mind for this.

OK, back to my own 'SECRET' project..... :  :twisted:  :music

 Keep happy.

Best regards to all.

Sandy. :computer  

[bogstandard]

Hi Sandy,
Nice to hear from you, and all the suggestions as well.
The timing on this engine is about as basic as you can get.
I had already looked at the slip eccentric method as being about the easiest possibility, just stop the engine, rotate the flywheel by 180 degrees and restart. I might still go for that method.
But one way I thought of doing it is on the (now famous) sketch. It would make the engine look a little more 'technical'. Not quite shown right, the pivot point should be in line with the eccentric arm top fulcrum point.
The cutters are in fact very special countersinking bits, with a hole up the middle, so by varying the depth of cut, the more wide the circle while the 'hole' stays the same size.

John

[sandy_ACS]

   :twisted:

Hi PD's,

John..... Thanks for the sketch..... I had a think    :nose about it for a while and came up with the attached.

What you are proposing is very similar to the 'Crampton' type of link motion, as used on the 'Crampton' locomotive.
The main difference is that on the True 'Crampton' there was a much wider slot in the combining link for about 15 degrees either side of the centre, which produced a dead motion as far as the valve was concerned... i.e no valve movement, I'm not entirely sure why this was, however, It may have been something to do with the way the loco engineers had to move the reversing gear.

For your use something on the lines as drawn should work reasonably well if you can squeeze it all in.
The only thing to consider is the need for the 'Lifting links' to be connected at the top of the eccentric strap (where the pin goes through the die block) and to be long enough to swing easily through a fairly large arc radius...otherwise you will find the eccentric strap will be pulled out of true as the motion operates.

Hope you find this of some use.  

The cutters you describe are similar to the 'Rotabroach' type.... these are also hollow and were designed for cutting large dia holes through thick materials (especially on milling machines) but with a much lower cutting force required... and less swarf to get rid of...
a bit like a core drill, but for metal.... HELL of a price each though!!!!

Keep up the great work.

Best regards.

Sandy. :vacat

[bogstandard]

Here is a bit of technical stuff for assistance in building these little engines. A lot of Elmers designs use the same dimensions for cylinders and PCD's on his plans, so this jig is a 'saver' in case I want to build another of his designs. On this engine there are six sets to be drilled and would mean remounting into the rotary table or using co-ordinate drilling. This is designed to just drop on and spot thru.
The first two pics show the jig and how it is used, the third shows all the holes drilled, with a massive saving in time and effort, plus they all line up perfectly.

John

[derekwarner_decoy]

OK PD's ....finally convinced our Bogstandard [John Moore] to show his TRU colours

[bogstandard]

Hi All,
Doesn't look like much has been done, but a lot of it is hidden.
I have managed to get the cylinder and standard all made, plus the conrod finished. All the races are now fitted, shielded from the elements and covered up.
The first pic shows the work that has been done to date, plus it has been basically bolted together to see if anything locks up. Smooth as a baby's bum.
The second is just a pic from the side. The flywheel is off for modification, I didn't know how much room I would have on the top plate until this work was done, so my first choice of reversing the engine has now been abandoned and I am going for a slip eccentric, I suppose if it is OK for full sized steam locos, it will do for this little engine.
The next bit is the hard part, getting the valve gear sorted.

John

[mushroom]

Hello all,
            Having just joined this forum....(courtesy of one member of Model Engineer Clearing House forum) may I say what a lovely design for your mine engine John, can it be adapted to run a Paddle steamer?
I am currently about 60% through the build of the James Coombes table engine, which is the same or very similar to the working design of your mine engine.
The engine is comprised of cast iron and gunmetal castings where it will be in contact with steam, the rest...brass, leaded steel, ''Peeke'' for seals.
Does anyone know the history of this particular engine?
I have built the Stuart 10V also the Score now working back to back on the Coombes and a single cylinder ''Corliss'' valved engine.
The archives of plans for engines is an excellent idea.
By the way ...I Stopped to Think...for about 6 months...Dont ...keep it up.
All the best for now,
                            John.

[bogstandard]

Hi John,
This isn't my design, I am just modifying a design of an engine that is in the downloads section, an Elmer Verburg plan, there is something for everyone in there.
I suppose it could power a paddler, but I wouldn't like to try it. For a start it really needs two cylinders to get the self start.
Hopefully in the not too distant future I will be designing and making a paddler engine for beginners to make, just like my piston valve engine http://www.paddleducks.co.uk/forum/viewtopic.php?t=2872 I did on here earlier in the year. Some ideas are already down on paper but until I get my health sorted (hopefully in the near future) I don't want to start any major projects just in case I can't finish them.

John