# 8" Steel Scotch Boiler



## Maryak (Feb 1, 2012)

I keep threatening to build a boiler. 

Well I've started to design one.

It's an 8" Dia Scotch boiler in Steel with copper tubes and a dry back.

At this point I've left the firing options open to either a spirit, (blowlamp) or coal.







Attached is an excel file covering the design parameters.

Best Regards
Bob 

View attachment Boilercalc.xls


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## Herbiev (Feb 2, 2012)

I shall be following this one Bob. Looks great :bow:


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## ref1ection (Feb 2, 2012)

Do you have any particular plans for it's use or is it just for the challenge of building it? Either way I'll be following along with interest Bob.

Ray


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## Dan Rowe (Feb 2, 2012)

Bob,
Thanks for posting the spread sheet. I see that you have used K.N. Harris for the estimated steam output.

Is this to be a scale African Queen?

Dan


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## firebird (Feb 2, 2012)

Hi Bob

I have a particular interest in boilers of all types so I will be watching also.

Cheers

Rich


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## kvom (Feb 2, 2012)

I'm guessing Bob has decided to convert his long-term hit&miss project to a steamer.  ;D


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## Maryak (Feb 3, 2012)

Herbie, Ray, Dan, Rich & Kvom,

Thanks for the interest guys. :bow: :bow: :bow: :bow: :bow:



			
				Dan Rowe  said:
			
		

> Bob,
> Thanks for posting the spread sheet. I see that you have used K.N. Harris for the estimated steam output.
> 
> Is this to be a scale African Queen?
> ...



No its actually to run my mill engine and I may add a couple of auxiliaries like a feed pump; and a fan if it ends up coal fired. Yes I did use quite a bit of Harris. I may have gone a bit over the top with the corrosion allowance but hey free 8" SD pipe is what I was given.



			
				kvom  said:
			
		

> I'm guessing Bob has decided to convert his long-term hit&miss project to a steamer.  ;D



I am almost at the assembly and see if it will run stage.......................but you may have a very valid point. :-\

Best Regards
Bob


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## tel (Feb 3, 2012)

> I'm guessing Bob has decided to convert his long-term hit&miss project to a steamer.  Grin



If not at least he'll be able to steam clean the beast!


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## steamer (Feb 3, 2012)

Dan Rowe  said:
			
		

> Bob,
> Thanks for posting the spread sheet. I see that you have used K.N. Harris for the estimated steam output.
> 
> Is this to be a scale African Queen?
> ...



I can assure you that Bob will not leave a screw driver in the safety valve that has to be kicked..... ;D

Dave


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## Maryak (Feb 3, 2012)

steamer  said:
			
		

> I can assure you that Bob will not leave a screw driver in the safety valve that has to be kicked..... ;D
> 
> Dave



True.................but I did once drop a chisel inside the rack and pinion of a 5" Parallel Slide Bulkhead valve. I could just get my arm down the inside of the case alongside the stem and with the aid of a water hose to keep the swelling down on my elbow and a mate to turn the hand wheel, it only took 4 hrs to get it out.  

Next time I used a lanyard on the chisel. 

Best Regards
Bob


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## steamer (Feb 3, 2012)

Well that may be Bob....but you did get it out! :big:

Dave


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## Maryak (Feb 13, 2012)

Hi Guys,

Well, I think the design is done. 






Attached is a PDF of the various bits and pieces.

Please feel free to offer a critique...............this is my 1st boiler design.

Best Regards
Bob 

View attachment Scotch_boiler.pdf


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## Dan Rowe (Feb 15, 2012)

Bob,
Nice design. You have a door for the front side of the tubes but what about the back side if they need to be replaced some time in the future?

Dan


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## steamer (Feb 15, 2012)

Agree with Dan.  Getting tubes out after 10 years is tough enough.
Though it looks like it's probably there already.

Dave


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## Maryak (Feb 15, 2012)

Dan Rowe  said:
			
		

> Bob,
> Nice design. You have a door for the front side of the tubes but what about the back side if they need to be replaced some time in the future?
> 
> Dan



Thanks Dan and Dave, :bow:

Actually the front door was more for cleaning and aesthetics than anything else. You raise a very valid point.

I have been thinking about this for a while and the best solution I can come up with is to make both the front and back end plates removable by either fitting a ring or a series of brackets and screwing the plates to them - not forgetting heaps of STAG.

I won't amend the drawings until any other suggestions are evaluated.

Best Regards
Bob


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## Maryak (Feb 25, 2012)

Hi Guys,

The attached PDF now has a grate and furnace accessories for solid fuel






Best Regards
Bob 

View attachment Scotch_boiler.pdf


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## steamer (Feb 25, 2012)

Interesting mount to the sleepers.....hadn't seen that before, but it makes sense

What keeps the boiler from rocking side to side?

Dave


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## arnoldb (Feb 26, 2012)

Looks great so far Bob :bow:

 ??? I cant see from your drawing how you're going to easily get to clean ash/crud out from below the grate if you're going to use solid fuel.

Kind regards, Arnold


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## tel (Feb 26, 2012)

> What keeps the boiler from rocking side to side?



The cradles it is sitting in?


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## Maryak (Feb 26, 2012)

arnoldb  said:
			
		

> Looks great so far Bob :bow:
> 
> ??? I cant see from your drawing how you're going to easily get to clean ash/crud out from below the grate if you're going to use solid fuel.
> 
> Kind regards, Arnold



The damper door on the front gives access to the ash pit under the grate. A curved bottom rake and a slicer would be made to fit. At least this furnace is not corrugated like its' full sized cousin, where raking out is a right royal pita.



			
				steamer  said:
			
		

> Interesting mount to the sleepers.....hadn't seen that before, but it makes sense
> 
> What keeps the boiler from rocking side to side?
> 
> Dave



tel, beat me to it. This is a copy of a full size marine installation. Believe me it ain't going anywhere, well and truly tested when some learner driver took out a 16" x 16" hardwood wharf upright at 8 knots. Mind you the concrete behind it stopped us fairly quickly. It also proved to be a great rust removal tool. The boiler room floor was ankle deep in the stuff. Lastly it was a fine opportunity to replace some 10' of rubbing strake.

Best Regards
Bob


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## steamer (Feb 26, 2012)

tel  said:
			
		

> The cradles it is sitting in?



Yup  I am sure what ever your design...won't go anywhere Bob ;D

Just couldn't tell from the 3/4 iso view.

Dave


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## Dan Rowe (Feb 26, 2012)

Bob,
That is looking really good. I see there is a plate on one end of the grate, as the grate is only about half the length of the furnace tube I am assuming the plate goes in the middle to act as a back stop for the coal.

You mentioned a fan for solid fuel a few posts back so I am wondering where the forced draft opening is? 

Dan


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## Maryak (Feb 26, 2012)

Dan Rowe  said:
			
		

> Bob,
> That is looking really good. I see there is a plate on one end of the grate, as the grate is only about half the length of the furnace tube I am assuming the plate goes in the middle to act as a back stop for the coal.
> 
> You mentioned a fan for solid fuel a few posts back so I am wondering where the forced draft opening is?
> ...



Hi Dan,

Thanks for stopping by. :bow:

Yes, the plate on the end of the grate is basically a poor mans brick arch. 

My 1st idea is to fire it with a blowlamp type burner using kerosene/paraffin.

For solid fuel, I am torn between induced draft using a blast pipe in the base of the funnel coupled to engine exhaust and using the lower half of the air space at the front, with some holes drilled through the lower half of the furnace tube and a sliding damper with handles on the front, (similar to an Admiralty closed register).

Best Regards
Bob


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## Dan Rowe (Feb 27, 2012)

Bob,
If you go with solid fuel and induced draft do you plan a steam blower for the engine to idle, and I think a suction fan would be needed for start up.

Some folks with locomotives have been using perforated metal for the grate. Here is a link for those on this side of the pond for perforated metal 1/4" thick with 1/4" holes.
http://www.onlinemetals.com/merchant.cfm?pid=15701&step=4&id=1004&top_cat=849

Dan


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## Maryak (Feb 27, 2012)

Dan,

You've really got the old grey matter bouncing around. My initial thought was that with the engine stopped there would be little requirement for draught but if needed a supplementary supply from the auxiliary stop could be arranged. For start up I had envisioned using compressed air. Don't ask me why but the suction fan has little appeal.

Best Regards
Bob


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## steamer (Feb 28, 2012)

Yup induced draft blower would be a good one to have. as well as injector nozzles with nice dry steam.

Dave


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## doubletop (Mar 4, 2012)

Nice one Bob, on my watch list now. 

I'd say you'll need the blower, the little gas fired Scotch I did the other year had to be started on a very low gas to get thing warmed up before it started to draw. I came to the conclusion that the folded design doesn't help this. If you are going to solid fire it I guess there would be even more need for a blower, although design is shorter and better proportioned to the real thing.

Pete


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## Maryak (Jul 13, 2012)

Dave and Pete,

It's been awhile but at the moment I'm waiting for some bits for the electrics on the Hit and Miss. So without further ado Today was the day to see if I could abuse my lathe to the point where it would machine the shell which is 8.75" OD.

Here's the result






















I managed a recess on each end to locate the smoke box plates which seemed like a better idea than welding in some blocks for screws.

If anybody tries to tell you 8" boiler tube is round, take it from me............it ain't 

Best Regards
Bob


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## Herbiev (Jul 13, 2012)

Looking good Bob. Can we have some more detail on the + at the tailstock end please. Are there adjusting bolts fixed to the back of the cross pieces?


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## Maryak (Jul 13, 2012)

Herbiev  said:
			
		

> Looking good Bob. Can we have some more detail on the + at the tailstock end please. Are there adjusting bolts fixed to the back of the cross pieces?



Hi Herbie,

The gizmo is commonly called a spider. The back side has a 1/2" nut welded near the end of each piece then 1/2" bolts are screwed into the nuts. This allows for it to be adjusted and centralised. Normally it's not a big deal but in this case I needed the adjustment for when I turned it around to machine to length and cut the second recess.

Best Regards
Bob


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## Herbiev (Jul 13, 2012)

Thanks Bob. Simply ingenious. :bow:


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## Diversion900 (Jul 14, 2012)

Good to see some progress Bob, I will be watching as the project moves along.

My own scotch had to be put on hold for a while as with the rest of my projects,
Life has an uncanny knack of upsetting ones playtime. 

Cheers Neil


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## steamer (Jul 14, 2012)

Maryak  said:
			
		

> Hi Herbie,
> 
> The gizmo is commonly called a spider. The back side has a 1/2" nut welded near the end of each piece then 1/2" bolts are screwed into the nuts. This allows for it to be adjusted and centralised. Normally it's not a big deal but in this case I needed the adjustment for when I turned it around to machine to length and cut the second recess.
> 
> ...



It's also been called a "cats head" though was semblance it has to a cat is beyond me.... ;D

Turned up some bronze plunger pump rams using a rig similar to that....they were'nt round either :big:

Dave


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## Maryak (Jul 20, 2012)

Hi Guys,

Well here we are again. 

I hope you are finding your way around. OK we were all familiar with the old setup and to be honest I think it was way more intuitive than this version.

Having said that, my tip is keep your eyes peeled as there are many more drop down menu's which give similar if not quite the same outcomes as those with which you were familiar.

Now about that boiler..............some time ago I bought a 3 in 1. Well today was the plasma cutter's first outing in earnest. I had to cut the 2 end plates from a biggish lump of 3/8" plate. 

I faffed about with test cuts, playing with amperage and air pressure until I managed a clean cut 

The cutter performed beyond my expectations and gave a better result than my friends single purpose cutter for which he paid close to $AU1000.

Now all I have to do is weld them together, marked them off, drill, bore, shape and chamfer them.

Avagoodweekend.

Oh and did I say I received the bits for my Hit and Miss Electrics. So next week I hope it's Chitty Chitty Bang Bang. 

Best Regards
Bob


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## Dan Rowe (Jul 20, 2012)

Hi Bob.
I am still watching this build. I am thinking about a similar boiler for my Stuart Cygnet.

What is a 3 in 1 other than a plasma cutter? I have never been happy with my skill with an OA gas axe.

Dan


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## Maryak (Jul 20, 2012)

Dan Rowe said:


> Hi Bob.
> I am still watching this build. I am thinking about a similar boiler for my Stuart Cygnet.
> 
> What is a 3 in 1 other than a plasma cutter? I have never been happy with my skill with an OA gas axe.
> ...



Hi Dan,

The other 2 are TIG and MMA welding. It's  a DC machine so, It will not successfully TIG weld Aluminium.

Best Regards
Bob


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## Herbiev (Jul 21, 2012)

I too could not believe the power of these plasma cutters. No more ridiculous rent for oxy/ acet bottles. Just hook up to the compressor and a clean smooth cut every time far better than I could get with the oxy/acet rig. Good investment Bob.


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## Maryak (Jul 28, 2012)

Hi Guys,

Yesterday was yet another test of my lathe, as I attempted to machine the furnace tube down to manageable sizes. The tube I scrounged was around 70mm dia with a wall thickness of 10mm. I wanted it to end up around 2-5/8" with a wall around 1/8"

With some 8" hanging out of the chuck I made up a kind of pipe centre to fit my running centre and the outside was machined to size.






Next came the inside. The tube is 7-3/8" long and so first up I had to remove the tailstock to get enough travel for the saddle and boring bar. My fixed steady was another problem as the provided maximum diameter was 2." More faffing about saw this modified to accept the 2-5/8" requirement.






.

At this stage all I can say is, the gods must be smiling, because I fluked the size of this thing just enough that my machinery will handle it. 

Best Regards
Bob


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## Maryak (Jul 28, 2012)

Attached is a revised set of plans.

Best Regards
Bob 

View attachment Boiler.pdf


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## Maryak (Aug 7, 2012)

Machining the furnace tube.

Outside






Inside






Best Regards
Bob


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## Maryak (Aug 10, 2012)

Oops,

Just noticed I posted the same thing twice, Ah well it's better than nonce 

After a bit of a delay for some real work, I did manage to get the tube plates welded together and marked off.







Best Regards
Bob


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## Maryak (Aug 17, 2012)

A bolt, a bolt, my kingdom for a bloody 5/16" bolt. Aha, found one, next  cut up some packing blocks, of course not before a scrounge around to  find the right size lump.

Finally the tube plates are mounted and clamped on the mill. I seem to remember a honeymoon that went along similar lines. 






Next came the boring job for the furnace which is about 3/4 done.






Best Regards
Bob


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## Dan Rowe (Aug 17, 2012)

Hi Bob,
Nice cuts... you will be needing a welder soon.

Dan


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## Maryak (Aug 25, 2012)

Thanks  Dan,

I have 2 stick welders and a TIG welder. I rather fancy TIG as it should be clean and slag free and hopefully will produce a better pressure weld. On the down side welding inside the shell kinda makes the TIG torch awkward due to the restricted area. Watch this space 

Yesterday I did manage to finish off the furnace tube boring on the plates. I know it's not much but SWMDBO wants floating shelves in the study, (3rd bedroom). So I spent quite a bit of time making custom wall brackets to match the custom shelves she selected :-*

Sorry about the crappy picture but between this and that, I forgot the camera and my mobile is nearly as old as I am. (IMHO, phones are for talking on, not all the other crap that's loaded into them so you are a bigger and easier target for even more spammers and phishers).






Best Regards
Bob


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## Maryak (Aug 31, 2012)

After a long and drawn out process, I finally have the tube plates ready for rounding and separating.


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## Maryak (Sep 8, 2012)

Hi Guys,

Yesterday saw me get the tube plates lined up and bolted down. A start was made on rounding the plates. It's going to be a slow process as the welds are as hard as the hobs of hell. The intermittent cuts require shallow cuts and 2 passes, otherwise the lathe starts to do the fandango. 

Best Regards
Bob


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## robcas631 (Sep 9, 2012)

That is really cool!


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## robcas631 (Sep 9, 2012)

So you are going to use the bolts to squeeze the tubes together? I believe it could work!


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## Maryak (Sep 9, 2012)

Hi Rob,

The tubes are copper and will be rolled into the tube plates.

Best Regards
Bob


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## Maryak (Sep 14, 2012)

Hi Guys,

The tube plates are finished


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## Herbiev (Sep 15, 2012)

Looking really good Bob. Looking forward to the next post


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## Diversion900 (Sep 15, 2012)

Looks like its coming along nicely Bob, still following with interest.....


Cheers, Neil


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## Maryak (Sep 15, 2012)

Herbie and Neil,

Thanks for stopping by and your support.

Best Regards
Bob


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## Maryak (Sep 21, 2012)

Hi All,

Today I had a clean up..............around 10kg of swarf and assorted  crap was extracted and dumped from places I had forgotten existed. Then I  had a play with my H&Miss but I'd left my electrical toolbox at  home...................So I made a start on the bosses for the various  ins and outs on the shell.

No pictures...........turning something round and drilling a hole in it is not terribly photogenic.

Best Regards
Bob


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## gus (Sep 21, 2012)

Congrats.You have done a great job precision drilling the tube holes into the tube sheets.

Are you using tube expanders? Or welding the tubes. This is another art and very tricky.


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## Maryak (Sep 21, 2012)

Hi Gus,

Thanks for stopping by and your support
	

	
	
		
		

		
		
	


	




The tubes will be copper and the plan is to expand them into the tube plates. This will mean making an expander for which I found some ideas on the net.

Best Regards
Bob


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## gus (Sep 21, 2012)

Maryak said:


> Hi Gus,
> 
> Thanks for stopping by and your support
> 
> ...



Hi Bob.

DIY your own tube expander will be tough. Heat treatment required.
Been using "Fuji" tube expanders to work on heat exchangers and aftercoolers.

Seen thousands of copper tubes expanded in power station.The Japanese Main Contract and surveyor plug gage tested every tube followed by H.Test.


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## Maryak (Mar 15, 2013)

Hi Guys,

It's been a while but I have finally managed to weld all the bosses onto the shell using tig.

Here are some piccys


























The dry pipe is ready for installation and then the serious business of the tube plates and furnace can commence.

Best Regards
Bob


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## Herbiev (Mar 15, 2013)

Looking great Bob. Ain't Tig welders a joy to use once you get the hang of it ?


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## ned100 (Mar 23, 2013)

Hi Bob,

I am following with great interest. Just wondering if you intend on getting the boiler certificated.  

One more thing,  I am also in the market for a 3 in1, but there are so many out there, it is a minefield - you sound happy with yours.  Would you mind letting us know which one you bought when you get a chance.

I am really enjoying your build - keep up the good work.

Cheers,

Ned


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## GYoung (Mar 23, 2013)

Been following your build with great interest.  A question about tube expanders.  I purchased one used by a/c - refrigeration mechanics for making tube to tube splices etc. without fittings. It uses a hand operated hydraulic pump with tubing adapters for sizes 3/8" to 1-1/2".  The price was not prohibitive.  Am I wrong in thinking that this tool would do the trick for model boiler builders?
Keep up the great work,
Gene


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## Maryak (Mar 25, 2013)

Hi Gene,

Thanks for stopping by.

My 3 in 1 is a Shillito C316 DC machine i.e. it won't weld aluminium and AC machines are big bucks plus this function is not important to me.

Your tube expander sounds OK to me. I found some plans on the net and intend to make my own. Mine will be what is in effect a tapered mandrel. Still with annealed copper and a dollop of tallow I'm hoping To expand the tubes without tooooooo much trouble.

Best Regards
Bob


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## Maryak (May 5, 2013)

The stays are done and now we are ready for welderama

















Best Regards
Bob


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## Diversion900 (Jun 1, 2013)

Lookin' good Bob


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## Maryak (Jun 4, 2013)

Thanks Div 900,

The major welding is now done but I'm not all that happy so, my pressure welding mates are going to fix it then I'll post some piccys.

Best Regards
Bob


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## joe d (Jun 4, 2013)

Hi Bob

Good to see some progress with this.  Looking forward to more...
(no pressure) (except, hopefully, in the boiler....)

Joe


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## Herbiev (Jun 5, 2013)

Hi Bob. Looking forward to the piccys.


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## Septic (Jun 5, 2013)

It's great to see people building real boilers.. I miss my old "Wee Chieftans" terribly _(even though they were old, cantankerous beasties)_


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## gus (Jun 6, 2013)

Hi Maryak,

Tube sheet very well done.As good as the professional heat exchanger maker.Bought n resupply n repair many tube&shell aftercoolers in the field.
Are you planning to expand steel tubes into tube sheet?  A good tube expander will be good investment. 

Will be following this thread. Now itching to build a steam boiler but will be limited in size.


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## Maryak (Jun 7, 2013)

Hi Guys,

Thanks for the support. :bow:

Well its all welded together 

A couple of shots and one of the copper tubes, all 27 of them which I spent today cutting to length 















Best Regards
Bob


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