johnsmachines

machines which I have made, am making, or intend to make, and some other stuff. If you find this site interesting, please leave a comment. I read every comment and respond to most.

Tag: boiler lagging

6″ Boiler Lagging -3, and back to the Dredger Engine.

The brass bands which secure the wooden lagging strips were installed.  5 bands were required to make sure that every piece of wood is held once the glue lets go.  The bands are only 4.75mm wide.   The bolts which apply the tension pass through small brass blocks which are silver soldered onto the ends of the strips.  (thanks Ben De Gabriel of EJ Winter for that tip!  And for the band material!)

 

IMG_6860.JPG

The boiler sitting on our kitchen table.  I will eventually paint the ashpit door assembly and angle plate at the base.

 

IMG_6859.JPG

 

IMG_6857.JPG

The setup for holding the small blocks in position during silver soldering.  In order to not close up the gap between the small block and the brass strap, I centre punched the blocks, raising small dimples, which produced a thou or two of separation between the parts, allowing the molten silver solder to flow.  That silver solder wire is 0.5mm diameter. 

 

 

And back to the Trevithick Dredger Engine….

 

IMG_6855.JPG

The redesigned inspection hatch.  The bronze rectangular bit plugs the hole in the end plate.   I have plugged the unwanted 14 holes in the end plate, using stainless steel threaded rod.   And metal worker’s hands, cut, dirty, dry thick skin (SWMBO “don’t come near me!”).

 

FullSizeRender 10.jpg

Four of the plugged holes around the firebox opening, 10 more under the inspection hatch (hidden), and the inspection hatch.  I will make the inspection hatch a little bit smaller.  It will be decorative, permanently attached and unable to be opened.  The dredger engine in the London Science Museum has the manufacturer’s name cast into the plate.  I am contemplating just inserting Richard Trevithick’s name and the date the first high pressure engine was made (1806).  There will need to be a separate area on the boiler wrapper the AMBSC identification.

 

 

 

 

Boiler Lagging -2

The Tasmanian Oak lagging looked too pale white to my eyes.  With use, steam, oil, dust, water, workshop grime and sunlight, it would have gradually acquired a well-used patina, but I prefer instant gratification.

IMG_6842

So after consulting my resident wood finish, artist, architect, expert, (SWMBO), I applied some wood-stain.

 

IMG_6846.JPG

Too orange, too patchy, she said.   And the white in the joins looked wrong.

Too orange, too patchy, and too much white showing.  “Put on some black boot polish” she directed.

So I did as I was told.

 

IMG_6848.JPG

With a boot polish brush…

 

 

 

IMG_6851.JPG

—and a toothbrush…

 

IMG_6852.JPG

… hmmmm.   I better clean her toothbrush before putting it back….

…(acknowledgments to Tubal Cain for using his old gag…)

 

IMG_6853.JPG

That’s the look I was wanting.

Now just waiting for the brass bands to arrive.

Ben De Gabriel from EJ Winter, Sydney, had sent me a remnant piece of banding to try, in my last consignment of parts from him.  It was perfect, but not enough for the 5 bands which I require.  So I rang him.  He thought that was the last of his stock of that particular size but he would check and let me know.  Sure enough, he returned the call, and he had found a couple more bits, and they would be just enough.  Old stock, a bit shop-soiled he said.  So I could have it for nothing!

Readers who have been with me for some time will know that I have bought 3 sets of engine castings and plans from EJ Winter.  The Bolton 7 horizontal Mill engine, the Bolton 12 Beam engine, and the Bolton 9 triple expansion engine.  A bit of very interesting news is that Ben is planning a new set of castings for the triple, using the lost wax casting technique, which gives a finish which should require machining on the mating surfaces only.  That sounds so good that I am almost tempted to make another triple.   Almost.   Some months until availability though.  (Hope that you don’t mind my premature announcement Ben.)

 

 

 

6″ Boiler. Lagging.

Lagging.  As in boiler insulation, not as in failing to keep up.  I have been working on the boiler for about 3 months, so I am actually happy with the progress.  And more than happy to have passed certification!

I decided to apply wooden lagging strips for the appearance and for ease of handling, rather than any minimal improvement in performance of the boiler.

After use, the boiler shell is too uncomfortably hot to handle, so there is a waiting time of 30 minutes or so to allow it to cool.  I am hoping that wooden lagging will reduce the waiting.

And wooden lagging will hide the splodges of silver solder around each boss and join.  And it looks the part IMO.

But how to attach it?  None of my books mentioned any method.  I presumed that the brass strips are the main method, and that is certainly so, on full-size boilers.   Then I found a short video on YouTube by Keith Appleton and I decided to copy his method.

The method uses Super Glue as a temporary securing method while positioning the strips, then applying brass strips to hold the wooden strips in place long term.  The boiler heat and expansion-contraction will result in the glue bond being temporary, and if the wood strips have to be removed later, for any reason, that will be possible. It also means that an insulating blanket cannot be inserted between the copper shell and the wooden strips, but I was not planning on using a blanket, so not a problem.

 

IMG_6821.JPG

The strips are 3x8x265mm.  I chose Tasmanian Oak which is actually an ash, because it is hard, fine grained, and I had some in old floor boards.  I cut the pieces to length a bit oversize, then ripped them to size on the bandsaw.  It is difficult to avoid fingers being close to the blade with small pieces like this, so I used a push stick.  I needed 65 pieces.  The blade teeth are a bit too coarse for this job, but I was too lazy to change it for a finer one.  Note the saw blade guide.  I did not like the one which was provided by Metabo, so I made that one.  Works well!

 

IMG_6822.JPG

Then I used a belt sander to remove most of the sawing marks.  The resulting thicknesses varied from 2.8 to 3.4mm but I hope that variation will not matter.

 

IMG_6824.JPG

Some hand sanding to remove wood fur.

 

IMG_6829.JPG

Hope that this will be enough pieces!

 

IMG_6830.JPG

The boiler feels out of place in all this woodworking rubbish.

 

FullSizeRender 18.jpg

SWMBO was away, so I set up on the kitchen table.  Here deciding on the final length of the strips.

 

IMG_6835.JPG

Each piece is cut to length, then fitted into position.  Shaping the wood to fit around bosses and fittings is done with a small sanding drum in the Dremel.  It is a slow process.  Then each piece is glued into place, and held with rubber bands.

 

IMG_6836.JPG

It has taken about 4 hours to apply about 1/3 of the strips.  The Baileys was to keep me in an appropriate mindset.  I am looking at the slightly ragged top and bottom edge in the photo.  Looks a bit rustic and authentic, or just rough?   The wood will be darkened after oiling, and possibly staining.  And Tasmanian Oak darkens with exposure to light.

That was yesterday.  Today I hope to complete this job, but SWMBO is home, and not appreciating the dust and mess, so I am exiled to the outside.

I have realised that to secure all of the wooden pieces I will require 5 brass bands.  I do not want it to look too brassy, so I am ordering narrower strips than the 6mm material which I had previously bought.  I think that 4.75mm will be about right.