Author Topic: Two-cylinder, double-acting wobbler  (Read 37377 times)

Offline Don1966

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Re: Two-cylinder, double-acting wobbler
« Reply #30 on: March 30, 2013, 08:29:23 PM »
Hi Simon, glad to see you back at it again. Nice job on the cylinders and crank throws. I am looking forward to seeing this one running. It should be an interesting engine. Love your photos.
 :ThumbsUp:
Don

Offline zeeprogrammer

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Re: Two-cylinder, double-acting wobbler
« Reply #31 on: March 30, 2013, 09:26:37 PM »
I'm also glad to see you back. I'd missed your post on the cylinders. They look great.
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
"To work. To work."
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Offline b.lindsey

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Re: Two-cylinder, double-acting wobbler
« Reply #32 on: March 30, 2013, 10:15:53 PM »
 Great to see your recent progress Simon...looking very good. I'm looking forward to seeing this one run too.

Bill

Offline arnoldb

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Re: Two-cylinder, double-acting wobbler
« Reply #33 on: April 01, 2013, 07:21:42 AM »
Looking very good Simon  :ThumbsUp:

A slitting saw in the mill after milling the webs also work a treat for slitting off the webs - I find it easier than doing the interrupted-cut parting off.  The webs just take a stroke or two over a fine file and a couple of strokes on some emery to clean up nicely.

Kind regards, Arnold
Building an engine takes Patience, Planning, Preparation and Machining.
Procrastination is nearly the same, but it precludes machining.
Thus, an engine will only be built once the procrastination stops and the machining begins!

Offline smfr

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Re: Two-cylinder, double-acting wobbler
« Reply #34 on: April 05, 2013, 06:45:32 AM »
A slitting saw in the mill after milling the webs also work a treat for slitting off the webs - I find it easier than doing the interrupted-cut parting off.  The webs just take a stroke or two over a fine file and a couple of strokes on some emery to clean up nicely.
*slaps forehead* of course! Why didn't I think of that?

Thanks for the encouragement, all. More coming right up...

Simon

Offline smfr

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Re: Two-cylinder, double-acting wobbler
« Reply #35 on: April 05, 2013, 07:03:01 AM »
The cylinders have a "seat" for the springs that will hold them in place, so these need to be machined and soldered on. This involves profiling the ends of a bit of 1/2" brass bar. I dug around in the brass box, and found a couple of stubs of bar. The ends were cleaned up, and a 1/8" hole drilled. This will take a pin that holds the part in place for soldering. Then the ends needed profiling to match the curve of the cylinder.

I made a simple fixture by milling a narrow slot then running a countersink down the slot to make a V-groove for the bits of bar to fit.



By keeping the table Y axis locked in place between making the groove and cutting the parts, I know I'm on center. With the bits of bar clamped in place in the groove, I can now use a boring head to make the end profiles, both at the same time:



which also allowed me to measure the diameter of cut and match the cylinder pretty well. Here are the results:



The profiled ends were then parted off to about 1/16" at the thinner part. They sit nicely on the cylinders. A matching hole for the soldering pin was milled in the cylinders, taking great care to avoid breaking through to the bore!



I'll solder these later.

Since I was set up to drill that little hole in the side of the cylinder, I also drilled the pivot and port holes in the cylinder faces. This was fairly straighforward. I just had to take care to get the spacing right, and to avoid drilling the pivot hole too deep. I used an indicator to ensure the port spacing was accurate:



One down, one to go:



Last night I applied Loctite to the bearings and body overhang parts, so now that it was dry, I could ream the bearings in situ:



Finally thing this is starting to come together!



I guess I should look for some small metric fasteners for the cylinder covers, and a grub screw for the flywheel, otherwise we'll have an awful mixture of metric and imperial threads (or even some BA!).

Simon

Offline tvoght

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Re: Two-cylinder, double-acting wobbler
« Reply #36 on: April 05, 2013, 03:24:10 PM »
Simon, I always enjoy your methodical approach, and your sequence for cutting these arcs was a great example..

The engine is taking its shape. I Really like it.

--Tim

Offline b.lindsey

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Re: Two-cylinder, double-acting wobbler
« Reply #37 on: April 05, 2013, 03:45:23 PM »
Nice set up Simon for cutting both radii at once. The "family" shot is looking great too...its really coming together.

Bill

Offline NickG

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Two-cylinder, double-acting wobbler
« Reply #38 on: April 05, 2013, 04:08:08 PM »
This is looking great Simon, I've often thought about doing such an engine for experience prior to attempting a slide valve type. This topic must have slipped through my net until now!

Offline Don1966

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Re: Two-cylinder, double-acting wobbler
« Reply #39 on: April 05, 2013, 06:23:41 PM »
Awesome Simon, love you techniques. It's always a pleasure to follow along with you.

Don

Offline smfr

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Re: Two-cylinder, double-acting wobbler
« Reply #40 on: April 06, 2013, 06:36:45 AM »
I got the spring seats soldered on this evening. Some stubs of 1/8" brass rod hold them in place:



I just put a ring of solder around those brass rods, having filed a flat on them to allow space for solder penetration. But I fear the penetration wasn't very good; this would have been a good use for solder sheet or paste, but I don't have any. Can anyone recommend a supplier in the US?

Anyway, these don't take great stresses so I don't think that the soldering will be a problem. Soldering always seems to make such a mess of carefully finished parts:


 
Another question I have is how best to smooth the bore where the port holes broke through? Perhaps just some careful filing and another go with the lap?

The other task for the evening was rounding off the column and the outriggers, a job for the rotary table. It took me way too long to come up with a good setup for the column, partly because the T-nuts come up higher than the table surface so need milling down. Anyway this worked without incident, which is a relief since I didn't want those glued parts to separate:



The two outriggers were ganged together with a bit of rod through the pivot hole, and done together:



Much prettier:



As you can see, the flywheel needs a finish pass once set on a spindle, which requires me to drill and tap for a set screw.

Simon
« Last Edit: April 06, 2013, 03:55:59 PM by smfr »

Offline NickG

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Two-cylinder, double-acting wobbler
« Reply #41 on: April 06, 2013, 10:19:37 AM »
Looks good that Simon, I agree silver solder does tend to make a mess of stuff. I prefer to use the rod separately and on small stuff just touch it and see a thin ring flash around the joint. This way you can keep trying so you don't overheat the component too. You've got to get the flux the right consistency so that it doesn't run and only have flux where you want solder, it is all easier said than done though. Try surrounding the component with fire bricks so it loses as little heat as possible. I wouldn't worry about where the ports come through, do the pistons travel past that point anyway? If so just take burrs off with a needle file or something. I think sometimes people get bogged down with fits and finishes, I've made oscillating engines that had scores up the bore, bell mouthed, sloppy fitting pistons and misaligned ports and they still ran! Just incase there are any beginners out there watching, reasonable clearances (not excessive) are the key to get a nice running engine, people make things far too tight and wonder why they don't run.

Offline Don1966

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Re: Two-cylinder, double-acting wobbler
« Reply #42 on: April 06, 2013, 01:49:01 PM »
Those solder joints look good to me Simon. The columns and outriggers came out really nice and adds to the overall look of the engine. Great job bud.

Don

Offline tvoght

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Re: Two-cylinder, double-acting wobbler
« Reply #43 on: April 06, 2013, 03:21:36 PM »
You asked about sheet solder. Since no one more qualified has responded, I'll mention that I got a roll .005 thick by maybe a half inch wide from
McMaster-Carr. They have other widths as well in the .005 thickness. Here's a URL.

http://www.mcmaster.com/#silver-solder/=m7b60s

Hope this helps,

--Tim

P.S No one else mentioned that the first picture (video?) in your last post shows up missing. Is it just me?

Offline steamer

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Re: Two-cylinder, double-acting wobbler
« Reply #44 on: April 06, 2013, 03:30:33 PM »
I noticed the video too Tim...

There is a silver solder paste that is sold by one of the gun smith suppliers too..Brownells I think.....solder and flux in one.

I don't think we need to wait for more qualified people to answer a question...we just need to be polite...something that isn't a real problem here on this forum :D

A consensus will form soon enough...and we all learn something with different perspectives and respectful discussion.

Dave
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Damned ijjit!

 

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