De Burring inside of boiler stays

[Speedy Builder5Participant @speedybuilder5]

[Speedy Builder5Participant @speedybuilder5]

I am building a 5" Speedy boiler, and find it difficult to de-burr the stay holes inside the boiler wrapper. I have a short stub of a drill mounted in a wooden knob, but it is difficult to get a nice 'countersink' ready for silver soldering. Any ideas ?

[Another JohnSParticipant @anotherjohns]

I'm probably a bit lazy; finishing up my 4th 3-1/2" gauge boiler.

Do your best; determine how the solder will be applied. The sides opposite to where the silver solder goes does not really need to be well countersunk.

I do use files and countersinks to try my best to clean up the holes.

Silver soldering is fun, but can be frustrating. Just remember that it really is not accurate machining that is required, but a little bit of space between components is.

Another JohnS.

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Hi SB5 ,

(1) Use Dremel type tool with the right angle head .

(2) Make what is effectively a pilot drill out of silversteel . Make a short D bit type contersink with a hole down the middle . Bond in a good length of rod just smaller than stay hole . Insert into hole from inside boiler and grip pilot part on the outside and twiddle . Could be done under power but just turning using a small hand held chuck probably enough .

(3) There are commercially available tools :

(a) A hand powered tool witha spring loaded collapsing cutter . Can be pushed through hole easily and when inside blade springs out . Smaller ones are just pulled back out again when done .

(b) A hand powered tool with no proper name but sometimes called a 'skrawker' . This is just a thng like an L shaped dental tool with a single sided backwards facing chisel blade on end . Small enough to wiggle through hole and then just used as a scraper .

Notes :

In aerospace industry there are exotic methods for deburring internal holes and passageways . Most common is abrasive slurry pumping .

In case of stay holes in copper boilers don't go much past the basic deburring stage – certainly don't make a significant countersink .

Regards ,

Michael Williams .

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