Author Topic: A Beginner's First Engine (Single-acting Oscillator)  (Read 4991 times)

Offline Kim

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #135 on: March 06, 2019, 01:47:55 AM »
Go with JB-Weld.  That's a high temp epoxy and should work well under heat.  That is, if you want to go the epoxy route.
Kim

Offline crueby

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #136 on: March 06, 2019, 02:08:32 AM »
Go with JB-Weld.  That's a high temp epoxy and should work well under heat.  That is, if you want to go the epoxy route.
Kim
Definitely, normal epoxy softens well well below steam temperatures, jb should be fine. Sand the mating surfaces with coarse grit to give it extra tooth, and be sure no oils on it.

Online gary.a.ayres

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #137 on: March 06, 2019, 07:26:31 AM »
Thanks guys:

@ Peter for raising the question and suggesting an alternative method.

@ Kim and Chris for suggesting JB Weld.

I already have some Araldite 'Steel' epoxy for metals, but it only works up to 65 degrees C, so I have just ordered some JB Weld from Amazon (287 degreees C). Am working the next two days, so hopefully it will arrive by Friday when I'm off again...

 :ThumbsUp:

Online gary.a.ayres

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #138 on: March 10, 2019, 11:42:03 PM »
It pains me when I am pulled away from the workshop at a weekend to fulfil other obligations. The sting is lessened, however, when these obligations include brewing 20 litres of Trappist-style pilsner:



I did get some time in the shop though. Following the advice of Chris, above, I looked to lapping the wear plate with a diamond-coated surface. As he thought may be the case, the diamond sharpening 'stone' that I already had (as in post #127 above) tended to flex and risked creating a curved surface, so I went to a local shop and bought this:



It is much more rigid than the other one, and has a coarse side and a fine side, though no specifications appear on the packet. To be honest, the job was trickier than I expected and I ended up using a 400 grit paper which seemed to create a better surface finish than the tool did. However, the wear plate got thinner to the point it was tending to flex as I lapped it, so I decided to stop:



 Perhaps it's fine, and I may have put in a lot of unnecessary work. Perhaps it's not fine. I decided the best thing was to leave it and see how it performs when I first hook up the engine to the boiler. If at that point it haemorrhages steam, it will probably be easier to lap it further when it's JB Welded to the standard than it was as a standalone. Equally, a new wear plate could be made and fixed on top of this one if this one is too uneven. But it might all be ok...

I'm guessing that the diamond tool could also be good for lapping pistons.

As the JB Weld hasn't arrived yet, I busied myself making the decorative holes at the top of the standard. These ranged from 12 mm down to 4 mm. They were marked out with a dry-wipe marker and a plastic drawing stencil featuring circles of many different sizes as well as other shapes. The centres were then picked out with a scriber, followed by an automatic centre punch  and a traditional centre punch. The wiggler was used to locate the punch marks, then they were centre-drilled and drilled to size. I was pretty careful to position these holes well, as one even slightly out of place would ruin the effect and make the whole engine look pretty clunky. Actually, I was pretty pleased by how it turned out:





 :cheers:

Online gary.a.ayres

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #139 on: March 11, 2019, 11:40:52 PM »
Today it was time to embrace the sticky stuff.

JB Weld - 'America's Toughest Weld', according to the packet - so if it's good enough for gluing together the steel girders of Manhattan skyscrapers, it's good enough for me in my little shed in a remote corner of the British Isles.

I glued the standard and wear plate together and clamped the assembly between two pieces of hardwood:



While I was waiting for it to set I completed the installation of the DRO on the x axis of my mill, so I now have a functional DRO, give or take some fine adjustment and the fitting of protective covers. Now I can get some serious machining done on the little engine and bring it closer to completion...

After six hours I thought I'd take the clamps off the JB Welded assembly in case some of the adhesive had squeezed out on to the surface of the part. I assumed that it might still be relatively easy to remove any excess after that period of time rather than leave it overnight until the stuff was rock hard. This appears to have been a good call. At first I thought the thing had welded itself to one of the pieces of hardwood, but a little leverage with a screwdriver sorted that out. There was indeed surplus JB Weld on the surface of the standard and plate, but it came off easily enough. There's still a slight line of it round the plate but I decided not to disturb that until it has cured overnight. Meanwhile, it's back between clamps again.



The next job tomorrow is to drill through the holes in the plate and tap for M2 cap head screws:




Online gary.a.ayres

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #140 on: March 12, 2019, 10:23:11 PM »
A productive day today. First, I drilled and tapped holes for the screws at the edges of the wear plate. I was so relieved at not breaking the brittle M2 tap that I took my eye off the ball afterwards and sheared off the head of the bottom right screw (visible in picture below). Disappointing, but the screws are decorative anyway and it was easy enough to drill out the headless screw and JB Weld another one (actually longer) in as a pin. I then set up the standard properly on the mill, using both axes of the DRO (install completed yesterday) for the first time. I have to say that using a DRO is transformational... :whoohoo:

The main holes were then all drilled from the numbers on the readout. I diverged from Steve's original plans by making the hole for the cylinder pivot 8 mm diameter instead of 4 mm, as I plan to add a bronze bush due to the standard being aluminium. Also, I may make a composite pivot (suggested by Tug on page 2 of this thread) if I can fit everything in.

The plans specify a rectangular standard with the steam inlet on the top edge. Due to the shape of mine I decided to bring the steam in at a jaunty angle on the left side. The picture shows the drilling setup for this:



I was on tenterhooks drilling that L-shaped passage and at one point I thought I had misread the quill DRO and overshot into the exhaust, but fortunately that was just paranoia  :paranoia:

The resulting hole was then widened to sufficient depth and tapped to accommodate a pipe-to-thread connector to match the pipe from the steam valve on my boiler. It could be argued that this is out of scale with the engine but I have to say I like the effect:



The main bearing was also screwed to the flywheel side of the engine.

With the standard complete, I cut the crankshaft to length, pushed it through the bearing and Loctited the crank in place:







Pleased to report that the flywheel and pulley run sweet and true. They are secured by grub screws so if I need to remove the crankshaft I'll  have to take them off given the crank is fixed with Loctite. This is something I'll avoid if possible as I'm afraid they may not run so nicely if I disturb them....

Offline Gas_mantle

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #141 on: March 12, 2019, 10:36:26 PM »
Looking good, you must be in a position now to try a test run   :)

The base reminds me of an old fashioned flat iron.

Offline crueby

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #142 on: March 12, 2019, 10:37:37 PM »
Excellent!!  :popcorn:

Online gary.a.ayres

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #143 on: March 12, 2019, 10:59:25 PM »
Thanks guys   :ThumbsUp:

@ Peter - I still have to make the pivot and nut, and find a suitable spring. Also not sure I did a great job on the wear plate, so it may need more work. Working next two days, so test run maybe beginning of next week...?

Agree the base looks like an iron, though each side is a different length   :)

Online b.lindsey

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #144 on: March 13, 2019, 12:38:43 AM »
It coming along well Gary. Looking forward to the run test.

Bill

Online gary.a.ayres

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #145 on: March 13, 2019, 06:42:29 AM »
Cheers Bill.

Online gary.a.ayres

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #146 on: March 16, 2019, 05:23:13 PM »
Poked three more decorative holes through the bottom of the standard, then enlarged the hole for the pivot and made a bronze bush for it. I'm going with Ramon's suggestion of a composite pivot (page 2 of this thread). The bush made a press fit into the hole. First press fit I have ever done, and I'm well chuffed. Hitherto, I considered press fits to be highly esoteric and not the business of mere mortals like me. I pushed the bush in in my bench vice, and OK it's not the tightest press fit in the world, but I don't think it's going anywhere, and if it doesn't then it's a press fit in my book. And if I can do it once...   :)



Only the pivot left to do, but that's tomorrow's job as now it's cider time!   :cheers:

Offline crueby

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #147 on: March 16, 2019, 06:19:55 PM »
Coming along great - can't be too many more parts to do before first spin.
 :popcorn: :popcorn: :popcorn:

Online gary.a.ayres

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #148 on: March 16, 2019, 06:21:38 PM »
Cheers Chris.

Just the pivot pin, the nut and the walnut base...

 :ThumbsUp:

Offline Gas_mantle

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #149 on: March 16, 2019, 06:41:35 PM »
Cheers Chris.

Just the pivot pin, the nut and the walnut base...

 :ThumbsUp:

On the home straight now Gary  :)

Are you going to add some sort of exhaust pipe on the rear? I think even something like a short piece of brass pipe will enhance it even more.