Author Topic: A Beginner's First Engine (Single-acting Oscillator)  (Read 6866 times)

Offline gary.a.ayres

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #210 on: March 26, 2019, 11:00:26 AM »
Tug -

thanks for all your good advice. I have the two fluxes shown for soft soldering:



I used the LA-CO last night. It's a thick paste. It seemed to be fine but Pete's post had me wondering so today I went out in search of a strong acid-based flux. I'm not sure whether the Baker's No 3 fluid fits the bill or not, but I see you have used it and will know that it's zinc chloride based.

Any thoughts from your good self or others on the relative merits of these two will be much appreciated. Until I hear anything, though, I'll test out the Baker's on some scrap brass.

Will bear in mind your other suggestions. The piano  wire seems like a 'sound' idea (sorry...) and I'll look at something equivalent after getting rid of the clamp and not looking for the material to glow dull red...

Online Jasonb

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #211 on: March 26, 2019, 12:15:23 PM »
I tend to use the paste even though I have Bakers Fluid on the shelf.

One other thing to bear in mind is when you are wiping the joint don't use anything with manmade fibres as they can melt, if using a sponge it should be natural. A cotton rag or paper is best. Same if applying flux to a hot surface with a brush - natural hair is best.

Offline gary.a.ayres

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #212 on: March 26, 2019, 01:03:23 PM »
Jason -

I used the small spare sponge that came with a soldering iron. Natural, I guess.

Will try the paper next, though it will just be to practice on scrap as the post has been and no brass bar today...

Cheers.

Offline Ramon

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #213 on: March 26, 2019, 01:13:51 PM »
Hi Gary,

Bakers fluid is a good flux but is very corrosive if traces of it are left. Folded paper as suggested is fine if fluxed but it will still scorch if contact is near static - unlike a piece of sponge though it's quickly replaceable.

If all the surfaces are clean and well fluxed it's all about getting the right amount of heat - as you've found any heat sink source can be a big hindrance in that direction. A gently applied heat to bring the parts up to temp and you will soon see the solder flow - that's the time to stop. Don't quench it but let it cool naturally - if you use Bakers then wash it thoroughly like Jason suggests.

Tug
"I ain't here for the long time but I am here for a good time"
(a very apt phrase - thanks to a well meaning MEM friend)

Offline 10KPete

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #214 on: March 26, 2019, 04:10:34 PM »
That Bakers Fluid sounds like the 'right stuff'! I like to tin with the acid then clean up. That almost eliminates any corrosive residue and makes finish job much cleaner. And as Tug said, everything should be very clean before heating.

Cheers!

Pete
Craftsman, Tinkerer, Curious Person.
Retired, finally!
SB 10K lathe, Benchmaster mill. And stuff.

Offline Gas_mantle

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #215 on: March 26, 2019, 04:46:35 PM »
The piano wire is a great idea Tug, I'll remember that for next time I need to do a similar job.

Offline crueby

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #216 on: March 26, 2019, 06:05:55 PM »
I am a little confused, are you using low or high temp solder?

Offline Ramon

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #217 on: March 26, 2019, 06:51:56 PM »
Hi Peter - it works well but make sure you have the prong points as in line as you can get them - the spring end shape isn't that important but if they aren't inline it can induce a sliding/twisting motion to the two parts as the solder melts.

Chris - This is soft soldering but I think Gary got a bit carried away with the heat last night  :)

Regards - Tug
"I ain't here for the long time but I am here for a good time"
(a very apt phrase - thanks to a well meaning MEM friend)

Offline Gas_mantle

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #218 on: March 26, 2019, 07:07:05 PM »
Thanks Tug. I guess and old wire coat hanger would do for some jobs.




Offline crueby

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #219 on: March 26, 2019, 07:16:17 PM »
Hi Peter - it works well but make sure you have the prong points as in line as you can get them - the spring end shape isn't that important but if they aren't inline it can induce a sliding/twisting motion to the two parts as the solder melts.

Chris - This is soft soldering but I think Gary got a bit carried away with the heat last night  :)

Regards - Tug
Okay - in the earlier post when he mentioned getting the parts red hot, I assumed it was hi temp silver solder. That is WAY too hot for soft soldering!

Offline gary.a.ayres

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #220 on: March 26, 2019, 11:15:19 PM »
Okay - in the earlier post when he mentioned getting the parts red hot, I assumed it was hi temp silver solder. That is WAY too hot for soft soldering!

Yes, indeed it is. And I'm ashamed to admit that I did it again today, and with the cylinder (!) which led to all sorts of complications.  It started off ok, tinning the parts with Baker's fluid:



Suffice to say that my first attempt came apart due to slippage when I tried to join them (using no pins or piano wire, mistakenly thinking that gravity would do the job as the parts are quite chunky), and I lightly clamped (yes, clamped!)   :facepalm: and overheated my second attempt for fear of it coming apart again. The join seems solid, but the cylinder distorted and went somewhat out of round to the point that the piston wouldn't fit into it   :( . I think this was due to a combination of excessive heating and the pressure from the clamp, which was not huge but big enough to do damage. Why did I clamp it when I had been advised not to? Well, I didn't feel that in my particular case it was acting as a heat sink as my test pieces from yesterday are rock solid. What I didn't take into account was the fact that I was blasting enough heat into the system from a powerful torch to allow the metal to distort even while the clamp and vice pulled the heat away. Never again, I promise.



I tried to rectify this by using the 'flex-hones', which resulted in the bore being too big for the piston! Thinking that I had lost it and that I would have to make a new cylinder, i.e. nothing to lose,  I decided to try cutting a groove in the piston...



... and adding an o-ring...



... and to my surprise it's a snug fit and pulls a nice vacuum.

This is just a black rubber o-ring, (from a box by Rolson, size R-04) and I believe that it's not the right kind, but I guess I could change it or use some graphite yarn. However, I'm wondering if I really have managed to salvage the result of a sloppy day's work or if that out-of-round bore will come back to haunt me. If it does, I'll just have to bite the bullet, remake the cylinder and try to learn from it.

Meanwhile, I have been using my Sievert torch for soft soldering. I'm thinking that maybe that's part of the problem. Should I be using a smaller DIY blowtorch instead?

Amazing that one stripped thread can send one on such a long and tortuous journey. And that everything in this pursuit impacts on everything else. And that a single acting oscillator is an easy build yet I'm having plenty of trouble with it. And that I thought soft soldering would be easy, yet I'm having more trouble with it than I have had with silver solder. And that even today, having been given lots of good advice, I was selective about what I followed, thinking it didn't all apply to my particular circumstances...

Sorry guys. Thinking this engine was finished and then having to go back and redo all this has led me into rushing things. Never a good way to go. I will persevere, and slow down...

I'll be making two engines of the same type, but twice the size, when I eventually get this one done. At that point I will follow Tug's suggestion of using pins to stop movement when soldering (though I still have to learn how to do that).

gary

Offline crueby

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #221 on: March 27, 2019, 01:03:05 AM »
Be great if the o ring salvages it. As for the sievert being too much, all depends which tip is on it, on the interchangeable ones you can go from a fine pencil flame to a boiler heating inferno.

Offline gary.a.ayres

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #222 on: March 27, 2019, 06:54:25 AM »
Thanks Chris.
It will be great if it does. If it doesn't, I'll have to make a new cylinder, in which case I'd be inclined to drill and ream the bore after I solder the plate on.
I'll also investigate other tips for the Sievert as I only have the 'boiler heating inferno' that came with it.

Online Jasonb

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #223 on: March 27, 2019, 07:09:46 AM »
A flex hone will do just that and flex to the shape of the cylinder so you won't really make it round with one of those.

The O ring is likely taking up the difference in shape so you may get away with swapping it for a silicon one but it may well wear on the tight spots and become loose over time.

Your existing torch will be OK just don't get carried away with it, most soft solders will melt around 200deg C which is only oven temp and you don't see your dishes or shelves getting red hot. Also don't be in a rush to move the part once soldered as the solder will form a "dry" joint if disturbed while still semi molten. I would not change my burner for a part like this or even smaller items. You can always turn the regulator down on the cylinder which will stop you overdoing it with teh trigger or handle valve.

last thing is that first photo meant to show the tinned surface?

Offline gary.a.ayres

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #224 on: March 27, 2019, 07:21:07 AM »
Thanks Jason.

Will keep in mind your points about the torch and regulator.

In your view, how would graphite yarn compare to a silicone o-ring in this case?

Yes, the first photo is meant to show the tinned surfaces. The indentation in the centre of the cylinder is where the solder has flowed into the original pivot hole with its stripped thread but not completely filled it.

Am I picking up that my tinning isn't what it should be....?