Cringle boiler build.

darwenguy · May 26, 2021

Hi all im just starting on another batch of my little boilers so will record a full build log with plenty of photo's.
This is the boiler as they look finished..

I do make these as finished models and aslo in kit form with preformed can ends. This is how the parts look in the kit form..

For this thread il record the whole process and so will show every step i take along the way.
So here goes it..
First cut stock close to size.. im making a set of 3 boilers, so 3 parts for boiler bodys and the longer section fo making the can ends.

The longer section is then slit down its length so it can be opend up to make flat plate..

The parts are then de-bured.

Next the longer section must be anealed to allow flattening..
This is the torch i use, this is the comonly available type but must have the high preasure regulater to work with the larger nozzle.

The part is then heated to a dull red..

And a quick quench in water removes most of the black oxide layer created from the heating..

The part can then be flattend by hand and finished with a mallet..

Thats all for now, il continue now and report more this evening.
Best regards.
Luke.

darwenguy · May 26, 2021

Next up i mark out and center punch all the hole centers. I use a scale printout to transfer the marks through and the outer diameter is scratched with dividers.

Then lots of drilling..

The plate can then be cut into rougth circles close to the outer diameter.

Then the stack of discs is mounted on the lathe and the outer diameter trimmed true. Then all edges filed and sand smooth..

The discs were then enealed and quenched..

The parts are then ready for the first round of spinning to form the flanges.
A hard steel former is used to shape the copper around to the correct diameter.
I would not recomend doing this on any small lathe or lathe you have much respect for as it requires a huge force on the spindle bearings.
After trying many, many! different, inteligent and time consuming ways to do this spinning process ive found the best method for me is...
just a length of 3x2 and some lard!
Ive tried all sorts of fancy roller setups and hardend steel bars and this is honestly the best method. Ive also tried many different lubricants and the good old lard out performs all of them. For those not in the uk lard is rendered beef fat, also known as beef dripping here. Its olden times name is 'tallow' one of the oldest used natural lubricants and makes the best chips too

hard wood works much better, pine is too soft and deformes or snaps too easily.

After the first spinning the parts were anealed again..

And after the second spinning and anealing...

The discs need a total of 3 goes on the spinning and enealing between each round. The parts are then reversed on the former and the flange trimmed to final dimesion..

And the fiinished can ends..

Thats all i got done today. Tomorrow i will get all the copper parts finished and make the boiler bushes.
Back soon.
Best regards.
Luke.

darwenguy · May 26, 2021

And the finished can ends......

I couldnt fit this on the last post as too many pics.

deeferdog · May 26, 2021

Copper end caps are readily available down under so I guess they are in the UK. There pics are of 100mm cap. Thickness is 1.5mm. Might save some work.

darwenguy · May 26, 2021

They look nice, and better quality to what ive seen here. There a good alternative for who dont want to beat or spin there own.
This boiler is 67mm diameter tube and the end caps are available here but they are much longer in length so need work to trim down and are quite awkward to secure and not deform them when drilling. There also around £15 each so well worth me making these ones.

Zeb · May 26, 2021

Very cool! Enjoying the build pics.

SmithDoor · May 26, 2021

Great photos

Dave

darwenguy · May 27, 2021

Hi all.
Little update on this, this morning i finished all the tube sections to final dimesion. This is the parts to be trimmed.

Copper is a rite pig to machine, the best method for me is very sharp tools(i use a new insert), high speeds, very light cuts and lots of light oil like wd40 to keep it cool.

Trim the sube sections to length and polish the ends. Use a file to flick of the bears but dont use a good one the copper soon ruins them. A little sanding cleans the ends.

I usualy use my neighbours large lathe for the cylinders. But just to show this can be done on a hobby lathe, place a canend in the cylinder to support it.
High speed, VERY light cuts and sharp tools is the route here.

Thats all the copper parts cut now and trimmed to length.

Next job is to drill the holes in the cylinders, il explain how i do that and then the parts can be put into the acid pickle while i make the boiler bushes.
More later.
Best regards.
Luke.

cobra · May 27, 2021

Great documentation.

darwenguy · May 27, 2021

Hi all, i got some more done today.
The boiler holes are drilled using the drawing plan. Just cut the paper and wrap around the cylinder then mark the holes through..

Then center drill and open up to 8mm.

Then all the copper parts can be cleaned and put in the acid bath.
I use industrial strength drain unblocker as it performs well and is more readily available than most industial chemichals here. This is the stuff i use, its sulphuric acid based... i put maybe 1/4 of a liter to 10 liter of water.

Citric acid also works okay but requires more mechanichal cleaning first and more time.

The parts are usually good after a few hours, a small fish tank heater can be used to speed things up but i usually just leave them in till the next day.

Then while the bits were in the pickle i got on with the boiler bushes, made from phospher bronze.

Nothing much to say about the making of the bushes just very basic turning and tapping.
But this is as far as i got with them today..

Just before this happend...

..

The lathe toothed drive pully exploded! Just looking for a replacement to order now. Il probably have a go at printing one or end up machining one before i get it though.
Back to it soon.
Best regards.
Luke.

timo_gross · May 27, 2021

:-( that is sad!

Is it a chicken egg problem? Need the lathe to fix the lathe?

Can you steal a pulley from the printer? Same size?

Just in case you think about it

Good thing on timing belt pulleys is that the tooth profile stays same for different pulley diameters. So you can grind the cutter and check its shape on the other pulley.

I threw some PLA Prints into hot water 60°C, PLA part into small plastic bag, then into the water, keeps the print dry but heats it evenly. Then pressed ball bearing into the slightly undersize hole of the "hot" plastic part. Worked surprisingly well and helped to get a tight fit to the bearing.

Cheers Timo

darwenguy · May 27, 2021

Hi Timo.
Im lucky i have a second lathe so i still have the egg

Just a pain in the arse.
But i have already ordered one from a uk supplier and only £4.
But im impatiant so still going to have a go at printing one in the morning. Ive found a 3d file already made online. I have ABS in my 3d printer and i think it would be tough enougth if i can get an acurate print.
Best regards.
Luke.

timo_gross · May 27, 2021

Hi Luke,

at £4 DIY becomes unfun, you should order the 2nd one too plus spare

"When you see a small cute bear an angry big bear is close by."
Or is the 2nd pulley made of another material?

I bought some cupper tube 2.1 mm wall thickness with 54 mm outside diameter 200 mm long. It was the largest cut off available.
Do you think that can be used for a small boiler? Not so easy to get started with a boiler. ( I cannot solder really need to figure that out first )
Right now I am in the reading state, so worst case I use it for something else.

Greetings Timo

darwenguy · May 27, 2021

Hi Timo.
Yes time is money after all, £4 is better than half a day to machine my own.
The other pulley is on the motor and is a metal one still in good condition but i did also order a new belt as the current one has done some good years of work.

I think the 54mm copper will work well for a small boiler, at 200mm there should be enougth material to make the boiler and end caps.
myford boy has made a video series on utube on the making of a small vertical boiler and i think he used the 54mm tube with just a single flue pipe. Worth a watch he shows a bit on the soldering process.
I should get these boilers soldered tomorrow and will take plenty of pics.
Best regards.
Luke.

darwenguy · May 28, 2021

Hi all, slow start this morning.
I did get a new pulley ordered for the lathe, but also have one cooking in the 3d printer so will try that later today.
In the mean time i can start the soldering of the fire tubes to the can ends the pics will explain best..
First all the required parts are removed from the acid and cleaned with dish soap and rinsed in clean water.
( i also fogot to mention earlier that the parts should be degreased in soapy water befor the acid as the grease will stop the acid getting to the copper!)

Dry all the parts and keep them clean!
They should be a nice matt pink color.

Then i prepare the silver solder, this is the solder that i use, its 1mm diameter and 500mm lengths, you will need up to 4 rods of this to finish the boiler.
Other brands are available but ive had consistant success with this product.

https://www.ebay.co.uk/itm/232012370546 for this step i form the solder into rings, the rings will spring open some so use a bar of aprox 8.5mm to form the rings. I found the cross bar of a lathe chuck key to be perfect for this.

Then simply coil a full length of solder around the rod, this should give enougth rings for the job.

Then snip into rings..

Then i mix up some flux paste, the rods always come with a little bag of flux but you will need about ten times this amount so i buy it in a larger size.
I use this flux with good success.

Use a little pot with a lid to mix up the past, a little drip of dish soap helps the flux stick. It does not require much water only a teaspoon full is enougth and mox to a youghurt consistancy.

Next up assembly and soldering of the fire tubes to the can ends..
Back soon.
Best regards.
Luke.

darwenguy · May 28, 2021

Hi all.
I got the parts soldered this afternoon, heres how i do it..
First put a ring onto the fire tube add plenty of flux then push into the can end..

Then add the next can end and wiggle all the tubes into position. Then add solder rings onto the top of the fire tubes and plenty of flux..

Now make sure everything is prepared for soldering, give yourself plenty of space and ventilation(im working under an extractor hood here. Also have some extra solder to hand.

Make sure to heat the whole assembly evenly and keep the flame moving. The flux will bubble off all the water then melt into a glassy looking liquid (the soap added earlier breaks the water serface tension and stops the flux beading up and dripping off)
Make sure all the joints have beaded and if not touch up joints with extra solder. Even heat helps here, solder will always jump to the hottest area so both parts of the joint must be hot. A harth of fire bricks helps keep heat in and i have to use somthing to keep the heat in during the winter months. The whole heating should be swift and usually done in 5 mins, here is the part after soldering...

A quench in water while its still hot helps remove most of the flux and oxide, i use a scouring pad to remove most of the loose crust just to save the acid a bit..

Then back into the pickle solution.

darwenguy · May 28, 2021

And...
Also got the 3d printed pulley to work

Its a little loose on the shaft so a bit noisey and probably wont last long. but plenty strong enougth and fits the belt perfect. Free file for this on thingyverse if anyone els ever needs this part.