# A portable engine



## firebird (Dec 3, 2011)

Hi

I have always fancied having a go at a portable engine, I just like them. Way back in July 2009 I asked a question here on Hmem re plans.

http://www.homemodelenginemachinist.com/index.php?topic=5456.0

I can't believe that was 2 1/2 years ago, doesn't time fly when your having fun.

Anyway having spent a good part of this year on tooling projects its time to get back to modelling. I am going to build a portable engine (freelance) with the boiler based on the type used on the Sissons portable engine which was serialised in the Model engineer magazine in July 1999. Casting kits were supposed to be available to build this model but as far as I can see they never were. The boiler is of a simpler type which I am confident is within my current skill level as opposed to the more complicated loco style of boiler. I won't be using any castings, I intend to fabricate everything. I won't be building exactly to the published plans, I shall be taking artistic licence, and using available materials. I may well take ideas from other types of portable engine as I progress and modify as necessary. For example the original plans call for a boiler diameter of 4 inches, I have sourced a piece of copper tube at 4 1/4 inches so I will have to make some modifications there and redraw the plans to suit.

Now before I go any further a question for our moderators. I own the magazines that the article was published in. Can I show sections of the plans to illustrate what I intend to do?

Cheers

Ric


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## Jasonb (Dec 3, 2011)

It will be good to see this one get going.

Brunell were saying that they were going to be doing castings for the Sissons a while back but can't see anything on their site now. May be worth an e-mail as Graham may have or know the wareabouts of patterns, though he's not known for getting back to customers 

I wouldn't mind seeing a pic either on the board or just PM'd.

J


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## tel (Dec 3, 2011)

I started a Sissons when the series was running, but didn't go on with it for some reason - probably got distracted onto something else. Should have a boiler barrel and a couple of bits and pieces down _there_ :hDe: somewhere!


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## firebird (Dec 3, 2011)

Hi

Tel, if you can dig it out I'd like to take a look.

Jason, thats right Brunell were going to do the castings but gave it up for some reason. As for pics I have googled several times trying to find a photo of a Sissons but always come up blank. We'll see what the mods say about showing extracts from the article.

Cheers

Rich


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## modelman1838 (Dec 3, 2011)

I built a Sissons portable when it was being serialised in ME in 1999, I have worked as a draughtsman all my working life and allways impressed on people the importance of working to drawing so that any errors could be rectified. I did just that and found when the boiler was finished that the safety valve went right through the centre of the chimney, so beware as I had to put up with an offset chimney, but it looked OK and worked fine.
I fabricated everything from scratch, but made the crosshead trunk guide and crank bracket in two pieces bolted together using steel for the guide and light alloy for the crank bracket. Most other parts were made to drawing with only minor changes.
Hugh


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## firebird (Dec 3, 2011)

Hi

Thanks for the tip Hugh, I'll watch for that. I will be using a piece of copper tube larger than the plans call for so I will have to redraw the plans anyway. Have you got any photos of your model, I would love to see it.

Cheers

Rich


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## Jasonb (Dec 4, 2011)

Rich, ask on Traction Talk Forum to see if anyone can turn up a photo of a full size.

http://www.tractiontalkforum.com/

J


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## steamer (Dec 4, 2011)

As far as copywrite Ric.  If you only show bits and pieces of the dwg, it's probably OK.

Full blown posting fo dwgs or pictures of full dwgs would probably get us in some hot water....less is better.

...on a personal note, this thread will probably the cheapest advertisment the plans have ever gotten...talk about target audience. :

Dave


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## bearcar1 (Dec 4, 2011)

I do not know if this is the model in question or not Rich, but here are a couple of images I took in Mt. Pleasant, Iowa in '05. Wish I had taken a few more of it but I was in a bit of a bind for time and it was 'shoot and go' situation. 

BC1
Jim


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## firebird (Dec 4, 2011)

Hi

That's the sort of thing Jim but that one has the loco style of boiler which is a bit beyond me at the moment. I do like the wooden wheels though.

Dave, that was my intention to just show any relevant bits, I'll stick a couple of bits up and see what you think.

Jason, thanks for the link I'll go and join them now.

Cheers

Rich


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## firebird (Dec 4, 2011)

Hi

This first image is what the Sissons portable engine looks like






The second image is of the boiler type.






Cheers

Rich


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## Jasonb (Dec 4, 2011)

That looks quite a straight forward boiler and as you say a lot easier than a loco.

Guess it should look something like the Seeking in this post on TT, quite an early style of portable.
http://www.tractiontalkforum.com/showthread.php?t=9357&highlight=sissons

As I mentioned earlier Prestons always have portables in stock, far more than are listed, if you are not too far away it will be worth a visit to their openday.

http://www.prestonservices.co.uk/portables.htm






J


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## firebird (Dec 4, 2011)

Hi

Jason, I signed up to Traction Talk but I can't view the images. They are asking me to make a donation??? towards the upkeep of the site. At the moment I am quite happy with being a member of HMEM and feel I would not benefit from paying to join another. It looks to be a really good forum but I can't justify the expense or find the time to make it worthwhile just yet. Thanks for the link anyway.

Cheers

Rich


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## firebird (Dec 4, 2011)

Hi Jason

I have just looked through Preston services web site. th_confused0052 th_confused0052 

I want one, any one will do, just deliver it when the wifes out.

Cheers

Rich


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## Jasonb (Dec 4, 2011)

Ah yes forgot about that being a donating member, you will still be able to see any photos in posts but not ones that are done as attachments. Do have a look around in both the full size and model sections, I correspond with a gug in Australia who is well advanced with a 2" Ruston portable, all from scratch except the flywheel, I'm sure he will chip in with any construction details.

Regarding the other matter if you have been a good boy who knows what Santa may bring 

I'll snip that photo and PM it to you.

J


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## Jasonb (Dec 4, 2011)

Managed to find the photos a the similar looking Seeking portable on teh web


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## firebird (Dec 4, 2011)

Well done Jason,

Thanks Thm: Thm:

Cheers

Rich


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## tel (Dec 5, 2011)

That's very close to the money, innit!

Had a look for my few bits yesterday, but they haven't surfaced yet


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## firebird (Dec 5, 2011)

Hi

Found a little bit of info

W. Sisson & Co. Ltd. was established in 1889 by William Sisson, who had taken over the small marine engineering works of J.J. Seekings & Co. near the docks. Noel S. Fowler's grandfather, R.S. Fowler, was apprenticed to Seekings & Co. in 1871 and worked at Sisson's until his retirement in the early 1920s. P.S. Fowler, Noel's father, became chief draughtsman for the firm in 1914, was appointed as managing director in 1946 and retired in 1958. Noel was apprenticed as a draughtsman in 1932 and retired in 1967
In 1958 Bellis and Morcom Ltd. acquired all the shares of Sisson and Co. as the culmination of twelve years of co-operation between the two firms [see D5748/1/3 and D5748/3/26]

Cheers

Rich


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## modelman1838 (Dec 5, 2011)

Hi Rich
    When I built the Sisson in 1999 I did`nt have a camera or a computer so did`nt take any pics, but now I have both. I still have the model so will dust it off and take a couple of photos. I have successfully put a few photos on photobucket, but when trying to put them on HMEM they have come out the wrong size, but will give it a go and if I get it wrong may be you can put me right, I may take a few days.

Hugh


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## Jasonb (Dec 6, 2011)

If you can't post the actual picture, just put up the "direct Link" not the "IMG code" you can just copy & paste from photobucket, should look liek the following

http://img.photobucket.com/albums/v156/jasonballamy/Seekingportable.jpg

J


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## firebird (Dec 6, 2011)

Hi

Thanks Hugh, I'd like to take a look at it.

Cheers

Rich


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## modelman1838 (Dec 7, 2011)

Hi Rich
Have taken a couple of photos of Sissons portable and put them on photobucket so will try to show them to you via the direct link as advised.
I have built a number of boilers over the years, but not a locomotive type but would like to, but as I only work alone it looks as though you could with a third hand when silver soldering.
An engine that I have allways liked the look of are those which drove the steam gallopers at the fair ground, these have locomotive type boilers and I believe made by a company named " Savage" but I have never seen any information on them, have you?.
Hugh

http://i1209.photobucket.com/albums/cc389/modelman1838/sissonsportable001.jpg


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## modelman1838 (Dec 7, 2011)

Rich
Have only managed to get one pic to you so will try again.

http://i1209.photobucket.com/albums/cc389/modelman1838/sissonsportable002.jpg


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## Jasonb (Dec 8, 2011)

Thats quite a nice little engien though looks like Hainings plumbing could do with scaling down a bit.

I've not seen plans for a centre engien but you can buy the actual "organ engine" that sat up front in kit form from Bruce engineering ( Page 17 ) and Reeves do a similar one called Nicholas. Then all you need to do is make up the rest so it looks like 

http://www.flickr.com/photos/[email protected]/1380779205/in/photostream


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## firebird (Dec 8, 2011)

Hi Hugh

Thats a nice looking engine, thanks for posting the pics. Did you ever have it running. I would like to steam the one I build and coal fire it.
Cheers

Rich


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## firebird (Dec 10, 2011)

Hi

When I built my small boiler I had to stop and build various jigs to hold the boiler tube without damaging it. Armed with that experience I decided to make the holdig jigs first for this project so that is what I have just spent the afternoon doing.

Firstly I cut a piece of 18mm MDF then in the mill machined the edges square. 












Can be nasty stuff MDF so I had the vacuum cleaner on all the time while maching it.

Cut a hole in it with my biggest hole saw.






Mounted it on the face plate from behind with large self tapping screws with some 6mm MDF spacers














Turned out the hole until the boiler tube just fits in






Then cut in half and screw and glue to another piece of machined square 18mm MDF











The addition of a bar will allow me to hold the tube in the jig with some plastic cable ties






A steel mandrel with a 10mm shaft and tapped 6mm






A piece of 22mm soft wood is marked out and then cut roughly to shape using the band saw vise
















Drilled through the centre 10mm and mounted on the mandrel and turned to size. I have marked the mandrel with a No. 1 so that I always put it in the chuck lined up with No. 1 jaw






Turned to be a good fit internally in the boiler tube






A piece of soft wood screwed onto the face plate











Another piece of 22mm soft wood cut roughly to size






Then screwed to the face plate and turned to be a good tight fit internally in the boiler tube and marked so that I can refit it if nec.











Mounted in the lathe. I can push the tailstock end into the boiler tube as far as nec depending on the job in hand






Heres a shot of the copper I have collected over the last year or so to make the boiler






Cheers

Rich


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## ShedBoy (Dec 10, 2011)

Building a boiler seems like no easy task, lots of jigs. Looks like an interesting project.
Brock


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## Jasonb (Dec 10, 2011)

Good to see you have made a start.

One thing I was thinking while looking at those pics of the Seeking engine and also the photo that accompanies Hainings series it that it would be nice to add the rivit detail. 

The ones at the ends of the boiler could all be dummies set into shallow csk holes in the barrel before soldering, there would be no loss of strength if the flanges were enlarged from 7/16 to 1/2. The side seams could be represented by using a strip of copper with a row of rivits down it that could be soft soldered onto the boiler after all the silver soldering, this would look a bit like a lap joint but not affect the strength of the tube.

I was talking with Harry Williams at Sandown yesterday and thats how all the rivits are done on his Kitson boiler, none are structural. Compare the early boiler photos with the ones where construction is more advanced

http://www.blackcountrysteam.co.uk/harry_williams_workshop.htm

J


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## firebird (Dec 10, 2011)

Hi

Brock, it will certainly be interesting and a long job.

Jason I had it in mind to simulate the rivets at each end. I will clad the barrel with wood so only the ends will show. I was thinking of making a ring with rivets in to slip over the ends, it would only need to be a tight fit.

Cheers

Rich


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## steamer (Dec 10, 2011)

That's coming along nice Rich!

Dave


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## firebird (Dec 11, 2011)

Thanks Dave

This morning I went out and had a good rummage through my stock (AKA the scrap boxes) and came up with a few bits. A cast bronze cylinder of unknown origin, I recall buying it at a steam fair years ago. It might do the job with a bit of modification. Also a bronze flywheel that would have come from a similar source. Some camshaft timing gears to give an idea of wheel size and some cast iron rings? although they look too small.
















Cheers

Rich


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## arnoldb (Dec 11, 2011)

Nice collection of bits so far Rich ;D

Chair pulled up to watch the rest of the build Thm:

Kind regards, Arnold


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## firebird (Dec 12, 2011)

Hi Arnold

You had better get a comfy chair I think this is going to be a long haul ;D ;D

Cheers

Rich


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## firebird (Dec 30, 2011)

Hi

Well Xmas is over,got my new lathe motor fitted yesterday so today I had the whole day playing. I have always liked the look of forged crankshafts and would like to fit one to this model. I have had an idea of how to make one for a while so gave it a go today. I built a jig from some angle iron and 1/2 square steel. Its designed so that each piece is fitted after each bend.

This is the jig. I'm using 7/16 round steel bar purely for the fact I have quite a bit in stock and can afford to waste some.






I made a mistake with the central part of the jig, it was too long giving the crank a 1 1/2 throw, 3 inch stroke so I reduced it to give a 3/4 inch throw, 1 1/2 stroke.






I centred the end of the steel before starting.






The first bend went well, heating the steel in the brazing hearth and pulling it round the jig by hand (a hand with a welding glove on) Sorry no photo of this bit I couldn't hold the camera and the hot steel but heres a shot of the steel being heated for the second bend.






Heres a few shots of the 4th bend.





















Unfortunately I didn't keep the heat on it enough and ended up with a crack.






The next attempt was a little more successful






A litle bit of straightening out in the press






Theres a crankshaft in there I think. Its 7/16 so the is plenty to machine off.






Cheers

Rich


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## cfellows (Dec 30, 2011)

That's pretty cool! I would never have thought to even try something like that! Hope you'll post the rest of the series as you machine the crank.

Chuck


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## firebird (Dec 30, 2011)

Hi Chuck,

This is just the practice one, I won't use it on this engine, not good enough. I'll need to refine the procedure a little but the idea works. My mate Julian (Barneydog) has just been round and said thats just what I need for one of my engines so I let him have it. What are mates for : : :

Cheers

Rich


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## Jasonb (Dec 31, 2011)

That looks the part 

Another method is to turn it from flat stock and just fettle the throws until they look like they were from round stock, you can get the bends to look nice and tight that way. Not as extream on a portable as this one but same principal

http://homepage.ntlworld.com/corromant/crankshaft.htm

Also has the advantage of being able to locate centres when turning the journal

J


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## steamer (Dec 31, 2011)

Nicely done Rich! I once saw an old industrial movie of someone forging a crank similar to that, but with a drop forge....If I can remember where the hell I saw it I'll post it.

Dave


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## bearcar1 (Dec 31, 2011)

Always thinking of different techniques to develop pieces aren't you Rich. BRAVO! I like it. My Father did more forging than I care to think about so I am a bit partial I suppose but pieces such as yours with some hammer marks just screams out character. By all means keep us in the loop please.

BC1
Jim


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## firebird (Jan 2, 2012)

Hi

Jason, Thats an interesting technique I'll bear it in mind, thanks.

Dave, if you can find it I would like to take a look.

Jim, I just love messing about with new ideas.

Sneaked a couple of hours today so had a go at another crankshaft. I have used the same jig with a few more holes drilled and tapped so I only had to juggle about with the existing bits. 







I've used a bit of 3/8 steel bar this time. The first bend I did cold in the press using the 90° point and a matching block.






The second bend I did with heat.






The 3rd bend.






And the 4th.






Pretty good but not quite good enough yet. The first and second bends are not equal, they look odd. I have either got to do them both cold or hot.






Cheers

Rich


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## Jasonb (Jan 2, 2012)

Rich if you cold press 1&2 into a flat bottomed "U" shape former with a bit of say 1/2" flat bar thats had the corners taken off that should give you an even tight bend.

Also worth heating the bar and letting it cool first as the annealing will let it bend a bit easier

J


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## firebird (Jan 2, 2012)

Hi Jason

I know about annealing copper, does steel anneal similarly??

Cheers

Rich


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## Jasonb (Jan 2, 2012)

Yep but don't quench, just let it cool by itself.


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## ShedBoy (Jan 2, 2012)

Ye old type crank shaft manufacture, I love it. It will be a very authentic looking crankshaft. 

Brock


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## firebird (Jan 2, 2012)

Hi

Thanks Jason and Brock.

At about the 2 min 50 sec mark in this vid there is JJ seekings portable, very nice.

[ame]http://youtu.be/7urKnVTsujk[/ame]

Cheers

Rich


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## Jasonb (Jan 3, 2012)

Shame its such a short clip but you should be able to get some details from it.

I know its not teh same style of portable but have you seen this rebuild thread on TT
http://www.tractiontalkforum.com/showthread.php?t=16665
It will only work for members so sign up if anyone else wants to see it.

J


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## firebird (Jan 3, 2012)

Hi Jason

Yes it is a shame but I have found a programme that allows you to down load youtubbe videos onto your own hard drive, from there I should be able to pull off some still shots.

Nice thread on TT but thats not a shed its heaven on earth :big: :big: :big:


Cheers

Rich


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## firebird (Jan 14, 2012)

Hi

I haven't been in the shop for a while but have had the last couple of days in there. I'm keen to pursue the idea of the forged crank so decided to give it another serious go. Crankshafts are one of the main parts of any engine so I figured if I could master it now it would make life easier in the future. heating the metal to red hot then trying to bend round a jig worked to some extent but i wasn't happy with it. I opted for annealing the steel bar first, thanks to Jason for that tip :bow: then cold pressing into shape. We have a pot bellied stove at work so I cut up a handful of 3/8 steel bar and dropped them in until they were nicely red all the way through then took them outand left them to cool slowly at the side of the fire.






For the jig I used a bit of 50mm x 25mm steel bar, its got to be heavy enough to stand the pressing force. First mill a slot along the top with a 3/8 ball nose cutter to a depth of 3/16.











Then mill a slot 1.25 wide






Make a couple of caps by first drilling some 25mm x 25mm square






Then chop in half on the band saw






Drill and tap the jig 5mm 






Drill the caps 5mm and attach with 5mm cap head bolts

In practice it didn't work too well, the crank did'nt form properly.






However it was straight which was encouraging. The next mod was to machine the slot in the jig deeper and profile the corners with a rotary tool to give a smoother action.






A piece of the 25mm x 25mm had a slot milled with a 3/8 ball nose cutter almost but not quite 3/8 deep and then drilled and tapped 6mm






A piece of 1/2 inch square steel bar has two corresponding 6mm holes drilled. When bolted across it will hold the 3/8 steel bar solidly






I used some copper grease in the slides to ease things.






This time I just pressed the first two bends.






Then started the third and fourth bends with a piece of tube.






One side was then pressed down and held in place with a cap then the final bend made






After some light tapping with a mallet across two v blocks the crank was put in the lathe and checked and some final adjustments made.






A bit of video. Note how quiet the new lathe motor is and how slow I can run it. 

http://youtu.be/YWh0Hrb-2Ec

Pretty good, I think iv'e got it cracked now.

Cheers

Rich


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## ShedBoy (Jan 14, 2012)

Nice job
Brock


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## firebird (Jan 15, 2012)

Hi

Thanks Brock

Today I made two little jigs to hold the shaft for turning the journal. I started by facing a bit of 50mm x 15mm 






Then centre drilled the 4 positions






Followed by a 3/8 drill through the two outer positions






Cut in half on the bandsaw






Which gave me 2 jigs
















I haven't decided yet whether to soft solder them to the crank or drill and tap each jig twice and fit a couple of grub screws to each

Cheers

Rich


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## Jasonb (Jan 17, 2012)

Rich, this looks like a finished Sissons part way down teh page. Wheels look like Mamod flywheels.

http://modelengineeringwebsite.com/Fabrication.html


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## firebird (Jan 17, 2012)

Hi Jason

Yeah thats it, thanks I'll save the pictures.

Cheers

Rich


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## firebird (Jan 20, 2012)

Hi

A quick question if I may. I hope to get a couple of hours in the shop tomorrow, what type of tool is best for machining the journal.

Cheers

Rich


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## Jasonb (Jan 21, 2012)

You can either grind up something like a parting tool with slightly radiused outer corners and relieve the mibble to stop chatter or go at it with alternate left and right hand turning tools blending where the two meet.


J


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## firebird (Jan 21, 2012)

Hi

Got a couple of hours in the shop today so I started by drilling and tapping the jigs for grub screws, 5/16 whit.
















One of the jigs will have a long grub screw to make it possible to attach it to the face plate.











The jigs are set between centres and the journal checked with a DTI






The journal ran out slightly, about .020, but that was due to the bends being not quite right. I machined the journal with a rear mounted parting tool which worked ok. The finished journal ended up at .291 which is not too bad.











Overall not too bad for a first attempt. I'll give it another go as and when time permits and try to refine it a little more.

Cheers

Rich


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## firebird (Feb 12, 2012)

Hi

Well its been a while since I posted any progress (domestic duties   ) but I did manage the afternoon yesterday. First thing I did was to mount the boiler tube in its holding jig and trim the ends square in the band saw.
















As I am not following the plans to the letter but allowing myself to run freelance I was going to increase the boiler length to around 9 inches or so. Looking at the tube I decided to leave it at its length of 11 7/8. Chopping off a piece @ 2 7/8 would be a waste and would result in a useless length of 4 1/4 dia copper tube so why not leave it on and make a bigger boiler and more substantial model. So for the time being it can stay uncut.

A Drawing






Cut out a couple of pieces of .083 copper plate on the band saw and file to size.






I decided to make a punch and die to form the end plates, a method I used very successfully on my other boiler. They can be made quite quickly. If you use the method of beating it over a former you still have to make a former. The previous nigt I glued together some 20mm thick hardwood off cuts, oak I think, into pairs. They were held under pressure in the press.






Drill the centre 6mm






Mark out






Cut the corners off to clear the lathe bed






Mount on the face plate with 2 6mm studs using the tail stock centre to align it centrally on the face plate






An old wood chisel ground up as a tool.






Having cut the hole to size about 20mm deep I had to screw the die onto the face plate from the rear and remove the studs.






Which allowed me to cut the recess for the copper disc to sit in for alignment











The punch is turned in a similar fashion






The punch and die are bolted together through the 2 central 6mm holes then have 2 6mm holes drilled on the edges for alignment pins and the two sides marked to aid alignment.





















Anneal the two copper plates
















The punch and die have a generous coating of copper grease
















Then with the plate sitting in the recess and the punch and die assembled its over to the press.






Thats the first one done






The second one was pressed similarly then into the pickle bath for a clean up.






Back in the lathe held on the punch with tail stock pressure on a scrap of hard wood






Trimmed to size (7/16) with a parting tool











A very light skim and they fit perfectly











A very satisfying afternoons work

Cheers

Rich


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## Blogwitch (Feb 12, 2012)

You've really got the hang of this boiler making now Rich, there's no stopping you.

Did you ever get to use that bit of tube I sent to you a few moons ago? I always wondered what you managed to make with it.


John


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## firebird (Feb 12, 2012)

Hi John

No Iv'e not used that yet. Its too good/not needed for something like this project. My eventual plan is to build a traction engine which it will be perfect for with its thicker wall. A few more skills to be learned first but don't worry John its sitting there in line waiting its turn.

Cheers

Rich


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## firebird (Mar 29, 2012)

Hi

Well its been a while since I had any shop time but the decorating is nearly done now so I'm getting back on track.
With a piece of 2 1/2 inch 10swg (1/8) copper tube now sourced for the firebox I decided to have a go at pressing the firebox tube plate, also 10swg (1/8) copper plate. I have used the same method as for the boiler end plates, I was keen to know whether or not the thicker plate could be pressed just as well.

The punch






And die






I made in a similar fashion to the boiler end plate punch and die out of hard wood.

A piece of 1/8 copper plate is cut out then filed to size






Until it is a nice fit in the machined guide recess in the die






The punch and die have guide pins fitted.






Plenty of copper grease to ease the pressing operation






Over to the press the copper plate, after annealing, is mounted in the punch and die






I stopped about half way through the pressing and re annealed the plate then pressed it in all the way






Not bad






It only needs light fettling now






I was pleasantly surprised how well and easily it pressed.

Cheers

Rich


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## cfellows (Mar 29, 2012)

Nice goin', Rich. I'm really surprised that the pressing operation worked as well as it did!

Chuck


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## cfellows (Mar 29, 2012)

Just read the bit about making the crankshaft. Very impressive! What's this copper grease stuff? Seems to be magic.

Chuck


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## Blogwitch (Mar 30, 2012)

That pressed really well Rich, considering the wall thickness to diameter ratio.

Very impressive.

Chuck,

It is a grease that is normally used on hot parts on automobiles, such as engine exhaust fixings, so that the parts don't corrode up too much and you can get them apart when needed, and certain areas of brakes, between the piston and disc brake pads to stop brake squeal. It is a basic anti seize grease, that has a lot of copper (or some other like material) in it.


John


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## Admiral_dk (Mar 30, 2012)

> What's this copper grease stuff? Seems to be magic



If I'm not mistaken, it's the only stuff you can use with car, motorcycle etc. brakes (heat resistant), so you can get it at autoshops.

And just as a warning in case somebody didn't understand the lubricating of brakes - NEVER use the grease on the brake pads, only on the rest of the moving parts in the brake system.


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## firebird (Mar 30, 2012)

Hi

Chuck, the crankshaft idea needs refining. Its almost there but not quite right. I'm not sure at the moment whether or not I'll pursue it any further. The copper grease is well known throughout the motor trade here in the UK and is a good general purpose grease for the home workshop I have found.

John, yes I was surprised how well it pressed. I think with a steel die and punch and a heavier press it would be possible to form it in one go. My home made press is only 6 ton which is why I stopped half way to re anneal. The wood punch and die has deformed slightly so will not be capable of being used again. All in all an interesting excercise though.

And like Admiral says not to be used on the actual brake linings.

Cheers

Rich


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## firebird (Apr 14, 2012)

Hi

I only had to give the tube plate a light skim to achieve a nice fit.







The inside had a small amount turned out as well to bring it back to the required size of 2 inch.






I'm going to fit 9 fire tubes. Its a bit of a squeeze to get them all in hence the reason for turning the inside diameter to size. The following sketch shows how tight things are.






I turned a wood spiggot to hold the fire box tube, I'll need to turn the ends square.











Also a wooden holder for the tube plate, a good tight fit. To be used when I drill the fire tube holes.











Cheers

Rich


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## firebird (Apr 15, 2012)

Hi

Don't ask me how I worked this out, it took me a few hours. There are times when I am mathematically challenged ??? ??? ??? Perhaps Marv will jump in here and explain the finer points

Anyway I worked out that 9 circles .5 inch diameter sit inside a 2.0 inch circle. 






Which in turn means each small circle is 40° from its neighbour.






With a rotary table set up and centred in the mill its easy enough to move the Y axis .75 inch to find the cntre of hole No. 1. I then went left and right 40° and 80° to holes 2 and 3 and 7 and 8. Holes 5 and 9 are directly below hole 1. That just left holes 4 and 6 to locate using the X and Y table movement.

I fitted a sacrificial table to the rotary table.

A practice piece of aluminium was marked out. I can use this as a jig to help hold the tubes when it comes to silver soldering them into the tube plate.






The plate then screwed onto the table. Following my drawing I centre drilled all the hole locations.











Then followed through with a 3/8 drill.






A 3/8 reamer by hand to clean up the holes.






The 3/8 tube fits well






The plate laid on top of the drawing, all lines up






The firebox standing on the drilled plate.






Finally today I centred and glued the wood block to the table that will hold the copper tube plate while I drill it.











heers

Rich


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## mklotz (Apr 15, 2012)

> Don't ask me how I worked this out, it took me a few hours. There are times when I am mathematically challenged  Perhaps Marv will jump in here and explain the finer points



When people are faced with problems that involve arranging small circles around a large circle they often want to divide the circumference of the large circle by the diameter of the smaller circles to determine the spacing. That is dead wrong. Take a few minutes with pencil and paper to convince yourself that it won't work.

The way to approach these problems is to find the angle that the small circle subtends at the center of the larger circle. I'll let it as an exercise for the student to show that, if

r = radius of small circle
R = radius of large circle

the angle subtended at the center of the large circle is given by

A = 2 * arcsin (r/R)

Let's see how this would work for Rich's parameters. With r = 0.25 (0.5" diameter circles), how big must R be to accommodate nine small circles?

A = 360/9 = 40 deg so

arcsin (0.25/R) = A/2 = 20 deg

Taking the sine of both sides of the equation, we have

0.25/R = sin (20) = 0.34

So

R = 0.25/0.34 = 0.735

and the enclosing circle would have a radius of

R + r = 0.735 + 0.25 = 0.985

IOW, very close to the two inch diameter Rich found by his manipulations.


If you're dealing with problems of this sort (eg, laying out an elbow engine cylinder), you may find the REVOLVER program on my page helpful. While originally written to assist me in designing tool holders, it's general enough to be applicable to other forms.


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## firebird (Apr 15, 2012)

Thm: Thm: Thm:


Thanks Marv, I knew you could do it. :big: :big:

Cheers

Rich


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## firebird (Apr 16, 2012)

Hi

The copper firebox tube plate is a good tight press fit onto the wood holder.






Using the same method as before all the hole locations are marked with a spot drill. (thanks to John Bogstandard for the tip about using spot drills instead of centre drills Thm






Then drilled through. I used a 9.5mm drill instead of the 3/8 this time. 9.5mm is slightly smaller than 3/8.






Clean up with a 3/8 reamer afterwards.






Sitting in the firebox with the jig.






Cheers

Rich


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## firebird (Apr 21, 2012)

Hi

Today I cut the hole in the boiler end plate for the firebox. After marking its position on the end plate I set it up in the 4 jaw.






Then cut out a hole close to size. The copper cuts easily with a normal turning tool.






Then bring to size with a boring tool. The last dozen or so cuts were taken a few thou at a time until the firebox would enter.











This is a view looking down the boiler barrel






The other end plate needs to be drilled for the fire tubes. I set it up in the mill using the punch to hold it.






After drilling the first 3 holes I secured it with a screw and removed the clamps so that I could turn the rotary table.






Then drilled the remaining holes.






Fitted into the boiler barrel.






A view looking down the firebox. The firetube holes are not correctly aligned yet.






Cheers

Rich


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## firebird (Apr 21, 2012)

Hi

I forgot to mention that the fire tube holes in the boiler end plate are drilled 1/8 inch higher so that the fire tubes when fitted have a slight upward slope. 

Cheers

Rich


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## arnoldb (Apr 22, 2012)

Good going Rich Thm:

Nearly time to get out the silver soldering kit 

Kind regards, Arnold


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## firebird (Apr 22, 2012)

Hi Arnold

The temptation to stick it all together is very strong but I have to be patient. I have to work out where all the various bushes will go, there are 3 stays to get in plus internal pads for mounting the cylinder and axles etc so the soldering job is a good way down the road yet.

Cheers

Rich


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## firebird (Apr 28, 2012)

Hi

I need to fabricate a cylinder so thats what I have been doing today. I had some success using a brake cylinder on my beam engine (an aluminium one) so decided to use one again although cast iron this time.

The cylinder I am using has a bore of .7 inch.

First job was to remove the unwanted portion.






Then face off in the 4 jaw chuck. It machines really well






Make a mandrel to hold it. Its machined to be a nice sliding fit in the bore. Partoff a bit to make a thick washer. Machine a shoilder for a O ring to sit on. Tightening the 6mm cap head bolt expands the O ring and grips the cylinder.











In the lathe and face off each end.






More to follow later

Cheers

Rich


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## firebird (Apr 28, 2012)

Hi

Drill out the threaded holes with a 5.9mm drill.






Press in some 6mm steel and some 1/8 steel into the smaller holes.






To make the saddle I chopped off a piece of steel tube in the bandsaw






In the lathe bored to size and cleaned up on the outside.






Checking the bore size with an offcut piece of the boiler barrel.






I'll cut a piece out of this now.

I need to machine the side of the cylinder now to the same radius as the saddle. Not sure how to do this so I'll post a question in the question and answers section.

Cheers

Rich


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## modelman1838 (Apr 28, 2012)

Rich
  I like the idea of using an "o" ring in an expanding mandrel. I know that rubber is incompressible similar to a fluid but have never thought of using one in this sort of situation, nice one.

Hugh.


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## firebird (Apr 29, 2012)

Hi Hugh

I can't remember where I first saw the idea but I have used it many times. I have about 7 or 8 of them now. Funny how there is never one the right size ??? ???

Cheers

Rich


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## firebird (Apr 29, 2012)

Hi

Managed a couple of hours this morning.

Cleaned up the face again to get rid of the protruding plugs.






Then machined one side of the cylinder with a fly cutter











Cut a steel block to size











Set up in the mill and using a laser cntre finder to set the boring head.











After cutting
















Cheers

Rich


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## Jasonb (Apr 29, 2012)

That looks a better height now.

So whats it to be silversolder the lot or just silver solder the steel block to the tube and then attatch the CI cyl with Csk screws from below?

Probably best to do a test solder joint with that bit you cut off and then decide depending on the outcome.

J


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## firebird (Apr 29, 2012)

Hi Jason

I think I will silver solder the steel block to the saddle and then try screwing that to the cylinder. It should be stong enough. The valve chest and cover will be fitted with studs. There is still quite a bit of work needed to the cylinder that will be easier without the saddle in the way.

Cheers

Rich


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## firebird (May 7, 2012)

Hi

A little more progress with fabricating the cylinder today. I decided to silver solder the spacer to the saddle but screw the cylinder on. The cylinder has a nicely honed bore already and I didn't want to spoil it with heat. The steel tube was mounted in the mill and had 3 holes drilled for the fixing screws. I have used 5mm stainless steel countersunk cap head screws for this.







Followed by 8 holes, 4 each side of 1/8 for mounting the cylinder to the boiler.











The spacer has a few centre punch marks to leave a gap between spacer and saddle for the silver solder.






After cutting out the section from the steel tube it was silver soldered to the spacer. Here it is set up in the brazing hearth fluxed and held together with copper wire






After a clean up the sides are squared up in the mill






Then the 3 mounting holes are drilled through 5mm






And countersunk






The cylinder has 3 corresponding holes drilled and tapped 5mm






I had to make a mandrel to hold the countersunk screws to skim a bit off the face and sides so that they would sit below the surface of the saddle






The parts screwed together






And sat on top of the boiler











Finally today I had a search through my stock and found a bit of 1/2 inch brass that will do to make the valve chest






Cheers

Rich


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## bearcar1 (May 7, 2012)

Oh nicely done, Rich. Terrific fabrication work, it looks like the real deal. Youza!


BC1
Jim


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## Jasonb (May 8, 2012)

Rich is there enough solder in that joint? looking at the last pic there is a gap at the front and you can even see light on the Righthand corner. Probably bot critical as its not under pressure and the screws add support but if it were structural I'd be looking for a bit more solder. Was the wired up photo posed as I can't see any flux.

Also are the holes in the saddle drilled vertically or radially, drill marks suggest vertically in which case your fixings won't sit well but it may just be my eyes.


J


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## firebird (May 8, 2012)

Hi

Thanks Jim.

Jason, yes there is plenty of solder in there, It flowed in quite well. Like you say the screws give all the support thats needed. It did occur to me afterwards that it probably doesn't need silver soldering as the 3 screws hold it pretty tight. The wired up photo wasn't posed, there is plenty of flux in there. I fluxed the spacer then sat it on the saddle.

If this trial one turns out ok and is the one I use I may add some fillets in the corners with some JB weld or similar before painting.

The 8 holes in the saddle are drilled radially. I turned the rotary table 19° in each direction.

Cheers

Rich


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## Blogwitch (May 9, 2012)

At the end of the day Rich, it doesn't matter how it is made or what it is made out of, as long as it runs and looks the part, and you are perfectly happy with it, what more could you want.

Coming along great there, solving problems as they occur. :bow: :bow:


John


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## firebird (May 9, 2012)

Hi John

Thanks. I absolutely love this hobby of ours and couldn't be happier than when I'm in the shop (shame I can't swing a few more hours each week but the senior management has different ideas : :)

The challenge of creating parts from my own design is my favourite part I think, especially when they work :big: :big: :big:.

Julian and I are off to the Harrogate model engineering exhibition this weekend to buy some much needed supplies to keep things going, a good day out.

Cheers

Rich


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## Blogwitch (May 9, 2012)

I wish I could be with you there Rich, but I just can't travel that far any more, it is not fair on whoever takes me to stop every 20 to 30 minutes for my sake, so I have now decided to give them all a miss.

We seem destined never to meet in person.


John


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## moconnor (May 9, 2012)

Hello Rich,

Another great project that you have going again. I have been intently following along.

Not a criticism, just an observation... when you were machining the radius on the saddle with your boring head, the finish that you ended up with would have been much improved if you would have rotated your tool 90 degrees clockwise (looking at the part in the vise with the photo captioned "After cutting.") and ran the mill in reverse so that the top of the tool would have contacted the material first. It looks like it was ploughing the material off the way the tool was oriented. In the end, I understand that it was a soldered surface and finish doesn't matter, but just for future reference.

Excellent work as always.

Kind regards,
Mike


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## Jasonb (May 10, 2012)

Mike, as I pointed out earlier that boring head screws onto the shank so running in reverse is very dangerous as its likely to unscrew, I know I have the same head!!

Would have been best to regrind a tool as the one shown is ground for use in the end of the holder but not really critical in this case as the surface will allow the silver solder to flow into the gap nicely.

J


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## browny289 (May 10, 2012)

love the fabrication mate 

another way with the boring head could have had the tool pointing upright and used normal cutting direction and started cut from the bottom and work up


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## moconnor (May 10, 2012)

Hello Rich,

I checked to make sure that no one had mentioned this (tool orientation) before I posted, but forgot about the other thread where you were looking for ideas on machining the radius. It appeared to me as if the tool wasn't re-ground for clockwise (normal) rotation and if so, would have presented a blunt edge to the material. Sorry about the duplicity. You had already received great advice from Jason and had it sorted.

Regards,
Mike


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## steamer (May 10, 2012)

Hadn't thought of using a old brake cylinder as a "casting".....nice bit a thinking there Rich

I really like the fab job! :bow:

Dave


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## firebird (May 10, 2012)

Hi Dave, 

the cast iron that the cylinders are made of machines beautifully and the bores are finished to a standard that I would find hard to achieve. Its a fair bit of work to fabricate the engine but the brake cylinders come free so I don't mind.

Hi Mike

I figured something was wrong with the finish I was getting but in this case it doesn't matter so much. I'm not that happy with the boring tools, they were cheap but you get what you pay for I suppose. when I was boring out the holes for the bearings in my high speed head stock for the Myford lathe I made my own tool which greatly improved the finish.

Thanks Browny

John, never say never.

Cheers

Rich


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## firebird (May 16, 2012)

Hi

A little progress.

I cut the hole in the valve chest. After machining the end square I drilled 4 x 1/4 inch holes.






Then joined them up with a 1/4 inch cutter.
















The hole doesn't have to be too accurate.

The cylinder and valve chest.






Cheers

Rich


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## mikegw1961 (May 17, 2012)

Rich

I think you are making a super job of this build and have followed it from the start.

I would like to have a look at the drawing of this model. Would you mind telling me where you got the drawings for this Portable engine from. 

Keep up the good work

Mike


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## Jasonb (May 17, 2012)

Mike, read the first post in the thread details of the drawings that this engine are loosely based on are in there but its being made to suit available materials so is a one off.

J


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## mikegw1961 (May 17, 2012)

Thanks Jason

Found the construction notes and castings on the Brunell website for the Sissons Portable Engine. Ordered the construction notes

Sorry for the interuption in the thread


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## firebird (May 17, 2012)

Hi Mike 

No problem, I have sent you a PM.

Cheers

Rich


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## firebird (May 17, 2012)

Hi

Drilled the stud holes in the valve chest tonight as per the drawing.











Cheers

Rich


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## firebird (Jun 17, 2012)

Hi

Long time no see. I have had some domestic duties to attend to and had a 1 week holiday in New York, fabulous ;D ;D

Anyway today was fathers day so I was allowed out to play for a while.

The valve chaest wa parted from its parent material leaving enough spare.







Set up and faced in the 4 jaw.






In the mill I used a laser centre finder to locate the centre then lightly centre drilled.






Back in the lathe I set it up accurately with a spring loaded centre and a dial guage.






Then turned the spiggot (the bit that is the guide for the slide valve rod.






Then using a ball turner to round over the end. This is the first time I have used the ball turner on a job.











The valve chest was used to mark the position of the first stud hole which was then drilled and tapped 7 BA. I'm using 3/32 stainless steel for the studs which takes a 7 BA thread easily. I have a stock of 7 BA brass nuts. I made up a couple of studs to keep the valve chest in position. The valv chest was placed over the first stud and held while the second hole was drilled and tapped. Once 2 studs were in I could drill and tap the remaining holes using the valve chest as a guide.
















I made up 10 studs which are slightly over long at the moment but will be trimmed on final assembly.






The studs fitted and the valve chest tried for fit. Its just a touch tight at the moment and won't quite go on but the holes in the valve chest were drilled 3/32 so will stand having a clearance size drill run through.











Sat on the boiler.






Cheers

Rich


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## arnoldb (Jun 17, 2012)

Thm: Coming along very well Rich 

Are you going to make a separate valve plate, or just run the valve on the cylinder casting ?

Kind regards, Arnold


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## firebird (Jun 17, 2012)

Hi Arnold

Just run it on the cylinder casting. I'll probably make the valve from a bit of phospher bronze. Although I intend to run the engine on steam it won't get enough use to worry about wearing it out.

Cheers

Rich


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## firebird (Jun 19, 2012)

Hi

Clearance holes and the valve chest fits ok.











I started making the valve chest cover tonight from a piece of 1/8 brass. After drilling the first hole I used one of the studs to hold it together.






Another hole was drilled and fitted with another stud then the remaing holes drilled.






Cheers

Rich


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## firebird (Jun 23, 2012)

Hi

I finished off the valve chest cover then had to spend quite some time thinking scratch.gif scratch.gif

On the original plans I have a hole is drilled in the top of the boiler and the cylinder block sits directly on top with steam being admitted to the valve chest through chambers in the cylinder casting via a regulator valve. Because I have fabricated the cylinder it won't be possible to use that method. I have decided to screw a valve into the top of boiler from which a short pipe will deliver steam to a displacement lubricator fitted to the valve chest cover and directly into the steam chest.

This first picture shows the cylinder and a small valve I have (picked up at a steam fair) that I might use. Also a piece of 5/16 square brass that I have rounded over at one end.






In the 4 jaw chuck the square brass is drilled and tapped 1/4 X 40.






Then cross drilled 1/8.






A corresponding 1/8 hole is drilled in the valve chest cover.






The 2 pieces are silver soldered together.






After a clean up it looks Ok






I have started on the lubricator (A John Bogstandard design) and will post pictures later.

Cheers

Rich


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## firebird (Jun 24, 2012)

Hi

The displacement lubricator is a design by John Bogstandard :bow: and one that I have used twice before. Once on my small steam plant and once on the beam engine. I haven't worked to any drawings but to give you an idea of size the body is 7/8 inch long.

Hold a piece of 5/16 brass in a collet and drill down 5.5mm.






Slightly taper the hole with a centre drill, this will help the O ring seat better.






Tap 1/4 X 40






Centre in the mill and cross drill 1/8






Part off and face to length then add a bit of shape with a round profile cutter






Drill through






And tap 1/8 X 40






This is for the drain bung.

The 2 side connections are made from 1/4 round brass. Hold a piece in a collet and thread 1/4 X 40






Drill through 1/8






One piece is drilled with a centre drill which is 60° to make a seat for the coned pipe connection






Part the two connections off and machine to length. They are then screwed into a mandrel in the mill vice and the ends profiled with a 5/16 cutter to match the radius of the body.






A piece of 1/8 copper pipe is accurately centred in the mill. You can just see the red dot of the laser.






.

Very lightly touch with a centre drill






Then drill through one side onle with a 1mm drill






Cut off the pipe to 1 inch long.

A trial fit of the parts






The drain bung is made from 3/16 stainless steel. Machine down to 1/8 and thread 1/8 X 40






Cross drill 1/16






Part off and use the body as a mandrel to hold it in a collet. Face off and profile.






Press in a short length of 1/16 stainless steel to make the handle.






The filler bung is made in a similar fashion from 5/16 stainless steel.

The parts so far.






And loosely assembled for a trial fit






Set up in the brazing hearth. Make sure the hole in the copper pipe faces upwards. Note the silver solder wire wrapped around the joint area.






Its in the pickle now having a clean up. I'll show the finished lubricator when its been claned up and polished.

Cheers

Rich


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## arnoldb (Jun 26, 2012)

Good going Rich

I see you're also not averse to giving toolmaker's clamps a hard hot time in the hearth.

Kind regards, Arnold


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## Blogwitch (Jun 26, 2012)

Arnold,

They are so cheap here now that it is a shame not to abuse them.

http://www.arceurotrade.co.uk/Catalogue/Workholding/Small-Clamps

Most other things now for clamping are more expensive.

At one time it would be sacrilege, now it is using your brain. 


John


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## firebird (Jun 26, 2012)

Hi Arnold, John

I bought a set of 4 for about £10.00 at a show. Cheap as chips.

Cheers

Rich


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## Blogwitch (Jun 26, 2012)

As an aside, when clamping things tight together for silver soldering, you must ensure that the faces to be joined have pop marks on them to give space for the solder to flow into, 0.002" nominal.

But everyone knows that, as I do know that Richard uses that technique.


John


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## firebird (Jun 26, 2012)

Hi

Yes thats right John, I perhaps should have mentioned it to help those that have yet to try silver soldering. The square piece that is silver soldered to the valve chest cover has 4 light centre punch marks on the valve chest cover to keep the square piece just clear of the surface to allow the silver solder to flow between the 2 parts. The lubricator side connectors are a rough finish and do not fit the body exactly leaving a very small gap for the solder. If you look very closely at the picture of the lubricator clamped ready for soldering you can just see a small gap at the top of the left hand connector. Its second nature for me now and easily overlooked when posting but its a point well worth mentioning.

Cheers

Rich


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## firebird (Jun 30, 2012)

Hi

I had to spend quite some time cleaning up the parts. The valve chest cover had distorted a bit when silver soldering so I had to bring that back to flat with some wet and dry on a bit of glass as a surface plate. After a polish though they are starting to look like something. In this shot of the parts you can see 2 O rings and a thin brass lock nut, 1/4 X 40. 






The parts assembled.






Sat on top of the boiler.






This is the valve I will probably use and its likely position.











Cheers

Rich


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## firebird (Jul 1, 2012)

Hi

Although this engine is being built without plans as such. much of it so far being built as I go along some parts need to be more carefully worked out. The steam ports and slide valve being a good example. I will only get one chance at machining them so I have to get it right, mistakes can't be rectified. A drawing on the computer gives me a good chance of getting it right first time, hopefully : :

This is what I am going to do. There is a useful mixture of imperial and metric here. I have a 2mm mill cutter is the reason.






Cheers

Rich


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## Jasonb (Jul 1, 2012)

Its usual to have the exhause larger than the inlets so the steam can get out faster than it went in, I would increase to at least 3mm preferably 4mm


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## Don1966 (Jul 1, 2012)

Jason is correct, my engineering book say exhaust =port width x2, the Slide valve moves equally to each side of center position.


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## firebird (Jul 1, 2012)

Hi

Thanks Jason and Don. :bow: :bow:

I somehow figured it wasn't quite right. Thats the great thing about this forum, theres always someone to put you right. Many thanks. I'll amend the drawing and re post.

Cheers

Rich


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## firebird (Jul 1, 2012)

Hi

A question ???

Am I right in saying that in its central position the slide valve covers all 3 ports. When it moves to the right it uncovers the left admission port and when moving an equal amount to the left it uncovers the right admission port.

Cheers

Rich


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## arnoldb (Jul 1, 2012)

Hi Rich

That's correct. For a simple slide valve, the wall thickness on the port sides are also a fraction wider than the ports themselves to prevent connecting the inlet steam directly to the exhaust while opening.

Kind regards, Arnold


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## firebird (Jul 1, 2012)

hi Arnold

A quick drawing, slightly different to the previous one. This one shows the size of the steam chest.






The admission ports are 2mm wide x 8mm and the exhaust port is 4mm wide x 8mm. There is a 2mm wall thickness between admission and exhaust ports. The slide valve would be 12mm square with 2mm wide walls around the recess. This is about the best I can fit in I think but better than the previous design. What do you think.

Cheers

Rich


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## Jasonb (Jul 1, 2012)

With that port spacing I would be looking at a 14mm long slide valve (8mm recess and 3mm each end) you could probaly get away with 13mm long (8 & twice 2.5mm) is space is tight

J


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## arnoldb (Jul 1, 2012)

Hi Rich

I think that would be just dandy for optimum performance without any compensation for lead or lap. Maybe it might be better to add a bit of meat (0.1mm) to the wall thickness on the port side walls - i.e. make the length of the valve 12.1mm and the length of the recess 11.9mm - but that's just me keeping a bit of a machining allowance in mind.

Kind regards, Arnold

Well, Jason beat me, with easier tolerances - you might be better of with those Thm:


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## firebird (Jul 1, 2012)

hi

Thanks Arnold and Jason :bow: :bow:

I'll re draw again maybe tomorrow night and see what I can fit in.

Cheers

Rich


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## Don1966 (Jul 1, 2012)

There is a book called "Model Engineering, A guide to model workshop practice" you can get it for $9.95 from amazon. The port bars ( this is the space between ports and exhaust B1 and B2)should never be less in width than the steam ports; the width of the exhaust port (WE) should be twice that of the steam ports. Therefore the width of WE = one-eighth the stroke of the cylinder. The cavity of the slide valve must be exactly B1+WE+B2. The total length (T) of the valve (TV) depends on the lap adapted. The lap in a small power-engine should never exceed half the width of the steam port. (TV) therefore= T+lap1+ lap2. In small and slow model engines and locomotives the length of ports may be reduced to 3/8 or 1/4 of cylinder bore. 

I am not trying to step on anyone's toes here as Jason and Arnold are very capable guys and are very good at what they do. I am merely giving you what my manual says. There values are very close.

Regards Don


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## firebird (Jul 2, 2012)

Hi Don

Thanks for the input.

I'm going to study all this for a bit before proceeding.

Cheers

Rich


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