# Model Compressor---Maybe



## Brian Rupnow (Nov 27, 2017)

As many of you know, I am always looking for some novel piece of equipment I can build to run with my model engines. Nothing overly elaborate, but not something as simple as a Ferris wheel. It has to be something with good visuals. Whatever it is has to be visible as working within a three minute window, as that is about the limit of time people will devote to an on-line video. Last night as I was trying to go to sleep, I thought about a machine that blows up a balloon. Great visuals, color of my choice, and fun. It would have to be a piston style compressor with a fairly large displacement. (To fit into the 3 minute time window.) I'll have to think on that one a bit.


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## vederstein (Nov 28, 2017)

Well last summer I created this for the Maker Faire season.  It's not a metal project, but it was run by a steam engine.  There was considerable interest in it during the faires.  (Probably because it was so weird):

[ame]http://www.youtube.com/watch?v=kxABa1CiMpQ[/ame]


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## Brian Rupnow (Nov 28, 2017)

Very cool Vederstein.---Brian


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## bmac2 (Nov 28, 2017)

Vederstein Rube Goldberg would be proud!


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## JCSteam (Nov 30, 2017)

I assume you will have seen the slinky see saw? This is a step further and could be a challenge in getting the engine to power it at the correct speed to allow it go down the steps at the correct speed.

https://youtu.be/9dinVcBEDhQ


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## Brian Rupnow (Nov 30, 2017)

That makes my old "slinky machine" look pretty "lo-tech",


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## Brian Rupnow (Nov 30, 2017)

I never did get my "auto-reversing mechanism" to work. However, nothing gets wasted here. There may be a way to incorporate this gear cluster into a compressor.---Thinking----thinking---


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## vederstein (Dec 1, 2017)

I like slinky treadmills....

I've written some arduino code in the past that controlled a steam throttle via a stepper motor.  It measured shaft speed then opened and closed the throttle as required.  It wasn't a full PID control, but it got the job done for my case.

...Ved.


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## werowance (Dec 1, 2017)

i realize this susggestion isn't a compressor,  but when I first saw (as a kid) an I believe its called an archamedes screw pump.  I was fascinated by it when I was little and still am today. maybe some copper tube and a gear reduction to drive it?   just tossing in my own wishes here.  

and on the compressor,  I believe I saw a balloon pump on the web somewhere made by a machinist,  If you havnt already seen it ill try to find a link for it.


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## Brian Rupnow (Dec 1, 2017)

Okay--This looks promising---
[ame]https://www.youtube.com/watch?v=HhX-8RyP214[/ame]


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## Brian Rupnow (Dec 1, 2017)

It might be nice to use a couple of these in there also.


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## Brian Rupnow (Dec 1, 2017)

Hoo Boy----


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## Brian Rupnow (Dec 1, 2017)

I'm going to need 8 of these guys. Four for air being sucked into the cylinders to keep it from flowing back out when the piston reverses it's travel, and four for air going out of the cylinder to the balloon to prevent the air flowing back from the balloon into the cylinder. The "incoming air" units are all "stand alone". The "outgoing air" units will all be plumbed to a common spigot where the balloon attaches. There is some "gravity effect" with this type of valve, so all eight will have to be installed "right side up".


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## Charles Lamont (Dec 2, 2017)

Might be a good place to use nitrile or ptfe balls. So long as you use the coned seat shown in your drawing. (If you use steel or bronze balls, I think a square edge seat would be better.)

Also, what MJM460 said on MEM about clearance vols. Won't matter much for blowing up balloons though, but then
again good design is often no harder.


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## Brian Rupnow (Dec 2, 2017)

Well---That certainly looks interesting!! I have never built a Scotch Yoke mechanism before. I can recycle three of my gears and one large pulley from the "Auto-reversing mechanism" that didn't work.


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## Brian Rupnow (Dec 2, 2017)

That should do it---


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## WSMkid (Dec 2, 2017)

Brian, 
Any thought of a relief valve to let the balloon deflate and refill?

Air compressors and water pumps really intrigue me. At some point I would like to have an IC engine driving a compressor and using that air to run an air engine. In time I guess. 

Watching from afar as always,
GJ


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## Brian Rupnow (Dec 2, 2017)

No--I'll blow the balloon up, then see if it bleeds back down past the pistons overnight. If not, I'll pop the balloon.


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## WSMkid (Dec 2, 2017)

Shouldn't your check valves keep it isolated from the pistons?


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## Brian Rupnow (Dec 2, 2017)

WSMkid said:


> Shouldn't your check valves keep it isolated from the pistons?


They should.


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## Ghosty (Dec 2, 2017)

Brian,
Would it not be easy to fit a check valve in the top of the green tubing, will be watching as usual.

Cheers
Andrew


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## Brian Rupnow (Dec 2, 2017)

In small displacement pumps like this it works better to have the valves as close as possible to the cylinders.


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## Brian Rupnow (Dec 3, 2017)

So, I have all the reclaimed "odds and sods" from the auto-reversing mechanism that I never got to work. I can re-use two of the bras gears, the dark steel gear, the large pulley and the round part with three smaller holes in it at 120 degrees apart. I will also re-use the rack and flatbar, but not on this project.


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## Brian Rupnow (Dec 3, 2017)

Time to ask a question. I have looked a great number of Scotch Yoke engines on the internet, and all of them are single acting. This doesn't mean that there are non out there, but if so I haven't found any. Ergo, there may be some very good reason for that. It may be that there is too much bending moment imposed on the small diameter piston rod when the rotating member is at the extreme bottom or top of the slot in it's orbit. If I change my design to single acting, where I don't have to have a seal around the rod at the end closest to the center, I can run a much more robust rod. I could also dispense with the inboard cylinder caps and half of the valve bodies. It would pump air at only half the rate of the original design, but then again it's only work would be blowing up a balloon. comments please.


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## Goldflash (Dec 3, 2017)

Brian 
I used to help build and sell CNG compressors 3-4 stage up to 750 hp 3600 psig discharge.  I remember one company that  spent millions of dollars developing a small 4 cylinder 4 stage compressor using scotch yoke system and ceramic valves  for a home refueling . We ended up with a few samples that ended up as curiosities in the corner. 
You already have figured out how to design and make automatic inlet valves for your minature engines. so if you have those for letting the air in then all you need to do is reverse the design for the discharge valve. 
What pressure do you need for a balloon and what volume 
with a simple compressor you might only get 30-40% volumetric efficiency  to let the air out
Or use as really cheap  home handy man compressors use,  basic reed valves


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## nautilus29 (Dec 4, 2017)

Hey Brian, are you planning on using a bearing inside of the slotted Piston rod to help reduce friction?

I also can't help to notice that the movement of the slotted piece kind of looks like an auto reversing mechanism.  it travels back and forth in the horizontal direction, but stays stationary in the vertical.


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## stragenmitsuko (Dec 4, 2017)

vederstein said:


> I like slinky treadmills....
> 
> I've written some arduino code in the past that controlled a steam throttle via a stepper motor.  It measured shaft speed then opened and closed the throttle as required.  It wasn't a full PID control, but it got the job done for my case.
> 
> ...Ved.



Appologies for the OT , but a  cool project would be a steam engine with corliss valves and have an arduino control the valve opening . 
Kinda like a "fuel injected " version of trhe steam engine . 


Brian , lovely project as usual , I'm watching :thumbup:

Pat


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## Charles Lamont (Dec 4, 2017)

Brian Rupnow said:


> Time to ask a question.



I see no reason for not making it double acting if you want, other than that it is completely unnecessary. As, for that matter, is most of what we do here.

I recommend a die block or slipper between the crankpin and yoke.

If you go single acting you could have it done by Thursday.


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## Brian Rupnow (Dec 4, 2017)

Well, this is getting asinine!! I stopped by my material supplier and priced a foot of 1 1/4" square brass for cylinders. Quoted price was $55.00---Too rich for my blood. So--I bought a foot of 1 1/4" square cold rolled steel and a foot of 6" x 1/2" aluminum, and that cost $40.00 I may have to take up a second career as a belly dancer or something to pay for my hobbies.


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## Brian Rupnow (Dec 4, 2017)

Okay--A few changes. Biggest change is that we are going to aim for single acting. However--I have left sufficient room to add rod end caps to the cylinders and make them double acting if I have to. I have split the "yoke" into two halves that are bolted together. One half is threaded #8-32 and the other side has a #8 counterbore. I have added a bronze slider to the yoke shaft as was suggested by a forum member. The cylinders have a "thru bore" now instead of being blind on one end.


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## JCSteam (Dec 4, 2017)

Just thinking on deflating the balloon, you have a large pulley wheel at the rear, could a pin be located on this on the outer part, that would trigger a "dump valve" basically a large bore pipe with a spring shut ball valve. The pulley rotates, the pumps fill the balloon, then the pin in the wheel opens the valve for the balloon to deflate, yould need a slightly larger bore to allow the air to escape and the balloon to go flat. But it wouldn't require much modification to the design you have for it to work?


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## 10K Pete (Dec 4, 2017)

I like your design so far Brian. It should be fun to build and fun to operate!!
I would like to suggest that you make the sliding block at least as tall as it is wide, or maybe a bit taller, to avoid any tendency to try and cock in the slot. Even if the clearance is small the tendency is there...

:thumbup:

Pete


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## Brian Rupnow (Dec 4, 2017)

Every project has to have a beginning. This is really too soon after my last project, the twin reversing steam engine, but I was bored today, and you know what that does. I bought my 1 1/4" square stock for the cylinders in a 12" length, and I just have enough clearance to get in over-top of the stock with my chuck and edge finder. I couldn't do it with the stock setting in my vice, so it is setting flat on the mill table held in place by a setting angle and c-clamp. I will drill both ends with a small centering bit, then saw the cylinders to about 1/16" longer than finished length on my band saw. The cylinder bore has to be done in the lathe with my 4 jaw chuck, and that small center-drilled hole will be used for my centering set-up in the lathe.


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## Barnbikes (Dec 4, 2017)

I think you should make the check valves with glass bodies. It would be fun to watch them in action.


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## fcheslop (Dec 4, 2017)

Would it be possible to just use a ball bearing in the scotch crank
Iv used them on smaller engines with no ill effects


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## Brian Rupnow (Dec 4, 2017)

I could use a bearing, but the sliding block in my last 3D model will probably work better. The problem with using a bearing or any other round pin, is that you only get a "line contact" with the yoke. A sliding block distributes the load over a greater area.


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## fcheslop (Dec 5, 2017)

Thanks, I can see youre point it never crossed my mind as my applications are small low load unlike what you are doing
kind regards
frazer


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## Brian Rupnow (Dec 5, 2017)

This morning I carved out a pair of cylinders from the cold rolled steel square stock. I still have to clean up the bores a little bit with a 3 stone brake hone, but they are basically finished. I will hone them, then machine the pistons for as "airtight" a fit as I am capable of. A very finicky fit.--Tight enough to seal air but loose enough to slide through with a very light finger pressure.


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## Brian Rupnow (Dec 5, 2017)

Each cylinder has it's own piston now. The pistons are a lapped fit into the cylinders----as much as it can be. Lapping aluminum is a bit like trying to polish a turd.--It's too soft to lap properly. The pistons are at a point where they won't fall through the cylinders, but can be pushed through with a finger. I'll find out how good the fit really is when everything is finished.


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## Brian Rupnow (Dec 6, 2017)

Today was yoke day. Nothing too exciting, just milling, drilling, sawing and tapping. The piece of 1/4" rod stuck through the yoke is going to become the piston rod. I still have to square up the inside corners.


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## Brian Rupnow (Dec 7, 2017)

The pistons, piston rods, yoke and slider are finished. The piston rod is one solid piece right now, and is Loctited and cross-pinned to the yoke. I will let it set up for 24 hours, then cut away the center of the rod. I assembled the two piece yoke with the slider in place, because I didn't want to have to disassemble anything after I cut the center out of the piston rod.


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## Barnbikes (Dec 8, 2017)

Do you plan on cutting cooling fins or will the slow speed of it make it unneeded?

Will the cylinders need lubricating?


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## Brian Rupnow (Dec 8, 2017)

The low speed and the fact that there is no combustion should make fins unnecessary. The cylinders will get a squirt of oil before running--it won't take much.


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## Brian Rupnow (Dec 9, 2017)

This morning I reclaimed some of the 1/2" x 1 1/4" aluminum flatbar from my auto-reversing project and used it to make up the two cylinder supports. I don't know how well it shows up in the picture, but both pieces required 4-jaw work to turn the 1" diameter x 0.100" long "spigot" that fits down into the end of the cylinder. Its funny, 4 jaw work used to terrify/frustrate me but just as everyone said "Do it enough times and it will get easier." They were right of course. Now the biggest pain in the butt is changing chucks whenever I need to do something in the 4 jaw.--And no, I'm not so accomplished at it that I will do all of my work in the 4 jaw. The square corners have been machined/filed into the yoke and the bronze slider installed, as well as cutting the piece of 1/4" shaft out of the center of the yoke. I'm not really sure about these aluminum pistons. They seem "grabby" when slid in and out of the cylinders but that may change with some "running in".


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## Brian Rupnow (Dec 10, 2017)

It has been a snowy miserable weekend here and good wife has a cold, so I've spent more time than usual playing in my machine shop. The compressor is taking shape and beginning to look like the 3D model. The gears do mesh, and the pistons do slide back and forth, although somewhat reluctantly. I will finish up the baseplate and the drive disc that moves the yoke back and forth tomorrow, and then a bit of 'running in' on my bench set-up to loosen things up a bit. Once I get it moving freely, I will start on the 4 valves.


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## Brian Rupnow (Dec 11, 2017)

Here is the "running in" video.
[ame]https://www.youtube.com/watch?v=waGnhHYoS4o[/ame]


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## Herbiev (Dec 11, 2017)

Another great machine Brian. Enjoy the snow. We are heading for temperatures of 40 C here in Adelaide.


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## Brian Rupnow (Dec 12, 2017)

My Goodness--What a horrible day outside. We're getting lake effect snow coming in off Georgian Bay on the east side of Lake Huron and it's snowing so hard you can barely see. So far today I've ferried two grandchildren from school on the far side of Barrie to their home on the far side of Barrie. They couldn't both get the belly-ache at the same time. One in the morning and then a different one in the afternoon. I am still "dicking around" with the compressor to see if it's going to "free up" enough to be driven by an o-ring drive belt. I had it all loosened up, then took off the cylinders to install gaskets at each end and forgot to match-mark things before I reassembled it all. On re-assembly, I found it to be as stiff as it was at the beginning. I still don't have a real feel for whether I am going to o-ring the pistons or not.


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## Brian Rupnow (Dec 12, 2017)

Decision has been made. The aluminum pistons simply aren't going to cut it. The problem I'm running into is too many pieces bolted together to allow perfect alignment. I have to think on this now. I have the viton O-rings. I can make a new set of aluminum pistons and turn them 0.010" undersize, but I don't really want to use aluminum again. The current pistons are too short to get a grip on with my lathe chuck, and they only have a 3/16" center bore, so re-using them isn't an option. Steel pistons sliding in a steel cylinder don't sound like the greatest idea to me either. I do have plenty of cast iron "stubs" left over from other jobs that I could probably make new pistons out of. I also have a piece of type 901 blue nylon that I could use. Maybe even UHMW.  I will think on this overnight, and post whatever I do tomorrow.


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## 2002hummer (Dec 13, 2017)

Brian
Just noticed your build. Look interesting. I am going to follow this build. I know I will learn something from this.


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## Brian Rupnow (Dec 16, 2017)

All is well in compressor world. I managed to squeeze in an afternoons work and replaced the aluminum pistons with nylatron pistons of 0.990" diameter and added an o-ring to each piston.  This made an amazing difference in the torque required to turn the large pulley. Of course with O-rings and gaskets the "compression" is quite significant. I also fitted each cylinder onto a mandrel and squared up the mounting face to the bore. It wasn't out by much at all, but every little bit helps.  Soon I will make the four valves that are required.


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## Charles Lamont (Dec 17, 2017)

Brian, I think you would get a more reliable seal if you cone the valve seats the other way, convex, so the ball is sitting on an initially sharp edge.

The way you have the cone tangential to the ball gives a broad seat and an invitation to trap muck under the ball.

If you were to do as I suggest, then the ball would ideally be a bit smaller, say 1/8" for a 3/32" hole, or the hole bigger, up to 5/32" for a 3/16" ball.


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## Charles Lamont (Dec 20, 2017)

No news for a week. You OK Brian?


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## Jasonb (Dec 20, 2017)

Brian, you have a 26mm bore spindle the same as me. Make two pistons say 0.005 oversize and with ring groove to finished dept. Fix these onto either end of your long piston rod and then open up the chuck so you can pass one piston into the spindle than hold by piston rod and take very light cuts to true up the piston on the rod and bring it down to size. 

You now have a rod with a true piston on either end. Modify the design so that the scotch yoke sits nearer to the gear plate so the piston rod can pass right across it. Make two blocks so the rod can be clamped to the front of the yoke without having to cut it.

Agree with Charle sre seat direction, I mentioned the Cameron pump I made on the other forum, these are the ball seats, bore or D bit the hole a drill won't give a true round hole


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## Brian Rupnow (Dec 20, 2017)

No news this past week because I've been up to my ying yang in engineering design work. Everybody wants to clear out the last of their engineering budgets before the year end, so I'm working like a dog, just not on my own stuff. The nylatron pistons solved any binding issues that were happening. I will probably start the valves tomorrow.


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## Brian Rupnow (Dec 21, 2017)

Today has been officially designated "Valve making day". I finally got caught up with my "real" work, so decided today was the day. I did seriously consider making reverse cone valve seats as has been suggested by some, but I didn't have the right size steel balls, and this method has always worked very well for me anyways. I'm just killing a bit of time waiting for my Loctited crosspins to set up, and when I'm finished typing here, it will be time to do the rest of the assembly, which is always a bit tricky to not get Loctite on the steel balls.


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## Brian Rupnow (Dec 23, 2017)

The compressor is finished. Will it work?--I don't know. During the final stages of the build, before I attached the brass manifold, I held a balloon over each discharge valve at the ends of the cylinders, and turned the compressor pulley by hand, and yes, it did inflate the balloons. (I tested one cylinder at a time.) They very quickly went from all flopped over to blown up to shape, but then didn't want to inflate any farther. Of course that is encouraging, because the check valves work, otherwise the balloon wouldn't have blown up at all. With the manifold in place and driven at a much faster clip than I can manage by hand, getting the air from both cylinders instead of only one the balloons should inflate. I have to wait 24 hours now for some J.B. Weld to set up (that is how I attached the manifold to the top of the valves) and then we will have a proper test run.


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## Foozer (Dec 23, 2017)

"have to wait 24 hours"   Tease . . .


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## stragenmitsuko (Dec 23, 2017)

offcourse it'll work . 
Was there ever any doubt


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## Brian Rupnow (Dec 24, 2017)

This was the morning for the big "test run" of the scotch-yoke air compressor. It is too cold out in my main garage where I test run most of my engines, so I set up right on the corner of my desk in my office, and used my variable speed electric drill for a power source. The compressor does everything I had hoped it would, and I made a video of it running, blowing up a balloon. while I was waiting for the video to upload, I ran the drill some more, and was just reaching for my oil can to give it a squirt of lubrication, when the balloon burst and almost gave me a heart attack!! Ahh--boys and their toys--now I have to go help my wife tidy up in readiness for Christmas (I get the vacuuming job as she has a bit of back trouble). Then I get to shovel a foot of snow off the front steps. Merry Christmas to all of you.---Brian Rupnow
[ame]https://www.youtube.com/watch?v=0r1WNRZPuhM&t=69s[/ame]


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## Ghosty (Dec 24, 2017)

Brian,
Looks great, another gismo to run. 
Merry Christmas to you and yours from me and mine.

Cheers
Andrew


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## Brian Rupnow (Dec 27, 2017)

And here we have my final video for 2017. It shows the scotch-yoke compressor being driven by my overhead cam engine, thru my cone clutch. The compressor was a fun little "no stress" project and it gives me one more unusual thing to drive with my model engines.---Brian Rupnow
[ame]https://www.youtube.com/watch?v=aOkTT83o_Vs&feature=youtu.be[/ame]


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## ShopShoe (Dec 28, 2017)

Brian, I really did enjoy it. I have a semi-built hand cranked balloon compressor sitting in my shop which I will get back to some day. I have to make a new cylinder and piston because the volume of air it pumps is too small so it takes too long (Terribly Boring, You Bet.)

I enjoy all your little gadgets and your engine builds and hope to make some in the future.

Thank You for posting,

--ShopShoe


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## Brian Rupnow (Dec 28, 2017)

Thank you, Shopshoe. Mine would work better if I changed a pulley and sped it up a bit. People want to see the balloon pop.--I'm always glad to hear from someone who takes a bit of pleasure from what I post.---Brian


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## stragenmitsuko (Dec 28, 2017)

There was a videogame once it was called  the incredible machines or something like that . 
You had to combine all kinds of gears and belts and various mechanical parts to make a certain movement happen . There was a mouse in a wheel as a power source , and if I remember it right there was also a balloon that would trip switches when released .
Somehow this machine of yours reminds me of that game . 

Keep up the good work , here's another one who enjoy's your builds .  


Pat


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## Brian Rupnow (Dec 28, 2017)

Thank you Pat. I was looking around this morning for something to make a smaller pulley out of for my clutch, to speed things up a bit. Everybody across 3 forums want to see the balloon pop.---Brian


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## Barnbikes (Dec 28, 2017)

Figure out a very slow rising arm with a pin in the end.


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## dsage (Jan 1, 2018)

Hi Brian et.al.
I'm wondering why the videos you've posted only show as a black screen for me? (like a black picture). Nothing happens when I click on them and I don't see a link embedded in the frame.


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## Brian Rupnow (Jan 1, 2018)

DSAGE--I have no idea---sorry.


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## Brian Rupnow (Jan 1, 2018)

It's New Years day here, and having survived Christmas in grand style, I'm down on my computer playing. I would like to have the balloon blow up twice as fast as it currently does. I can either run the compressor twice as fast---or---Make each cylinder double acting. They are only single acting right now, with one end open to atmosphere. However, there is an alignment issue which caused some pretty severe binding between the aluminum pistons and the inside of the cylinder. I got around that by making a nylon piston 0.010" undersize and putting an o-ring on it. That same alignment issue would no doubt cause a "bind" between the cylinder rod and a rod end endcap.--Unless--I found a way to make an air-tight seal that still avoided metal to metal contact. I think what I show in the attached drawing would work. Make a 0.030" oversize hole in the metal endcap, then add a rubber o-ring with 1/4" i.d. (actually they are a bit less than 0.250"), and hold the o-ring in place with a Loctited brass sleeve. This will serve to keep an air-tight seal, but still allow enough clearance to prevent metal on metal binding. I will have to think on this for a bit.


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## Ghosty (Jan 1, 2018)

dsage said:


> Hi Brian et.al.
> I'm wondering why the videos you've posted only show as a black screen for me? (like a black picture). Nothing happens when I click on them and I don't see a link embedded in the frame.


 
dsage,
Right click on the black, open properties, copy Address(URL) and paste to your browser bar. Google wants every one to use their Chrome browser, when you open y-tube, you will see the blue bar across the top of the screen with this in it.
(Watch YouTube videos with Chrome.     Yes, get Chrome now.)

Hope this helps, 
Cheers
Andrew


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## Cogsy (Jan 1, 2018)

dsage said:


> Hi Brian et.al.
> I'm wondering why the videos you've posted only show as a black screen for me? (like a black picture). Nothing happens when I click on them and I don't see a link embedded in the frame.


 
As Ghosty says, it's a browser issue. Something with the forum software not liking IE anymore (now that IE has been officially retired this will happen with more and more sites over time). Chrome will fix it, as using other modern browsers as well. I'm not a huge fan of Chrome but something tells me I'll have to switch to it at some point.


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## dsage (Jan 2, 2018)

Thanks. I was on the right track but hadn't dug as far as Properties to find the URL. Usually there is a "copy URL" in the right click list.
Shame about IE. I wasn't aware it is obsolete. 
Sorry for the distraction.
At least now I can have a look at Brian's wonderful machine in action.

Thanks
Sage


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## Brian Rupnow (Jan 2, 2018)

So, here we are, two days into the new year, and I've eaten too much, rested too much, and read too much. It must be time to machine something. The cylinder rod end seals that I designed yesterday have become reality today. Before I Loctite the brass sleeves into place to lock the rubber O-rings in place, I thought I should put up a picture. After they are assembled, you won't see anything but the cap plates.


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## Brian Rupnow (Jan 2, 2018)

Of course nothing is ever easy. Since I already have my existing valves and manifold J B Welded in place, I am going to have to build a valve set-up that both sucks and blows from a common port in the side of the new rod end caps. This will be tied in with flexible hose to the existing manifold.


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## Brian Rupnow (Jan 3, 2018)

Everything went together as I had planned. It's close,--very close, but the yoke clears the end caps by about .030" at full stroke. I still have to make the valves that fit onto the two visible pipes sticking out from the side of the caps. I'm very pleased (and somewhat relieved) that everything goes round and round without any serious interferences.


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## Brian Rupnow (Jan 3, 2018)

The compressor is approaching the limits of what can be driven by a rubber o-ring drive belt. If cogged "timing pulley" drives weren't so horribly expensive I would use that to drive it. (The single set of two pulleys and a 3/8" wide belt as used on my overhead cam engine cost over $100 when shipping was factored in.) I am currently tossing around the idea of using a #25 pitch roller chain and sprockets. A "standard" old style bicycle chain is #35 with 1/2" center to center of rollers. A #25 pitch roller chain is 3/8" center to center of rollers, and a #25 sprocket is 1/8" wide. There is one size smaller of roller chain, the #1475 pitch series which is .1475" center to center of rollers and takes a 1/16" wide sprocket, but my gut tells me that is getting a bit too small. I will call Canadian Bearings tomorrow and get a price on the #25 pitch chain and sprockets.


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## Charles Lamont (Jan 3, 2018)

A Poly-V belt is cheap and should be available from an online supplier. The pulleys are not difficult to make.


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## Brian Rupnow (Jan 3, 2018)

Charles--I had to Google "poly v-belt" to see what it was. They would probable work, but they depend on tension to keep them from slipping. I would prefer a positive drive that doesn't depend on tension.


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## dsage (Jan 3, 2018)

Brian:

Try these guys for timing pulleys and belts. Close to you as well. (well sort of - Janetville).

http://www.steppermotorcanada.ca/index.html


Sage


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## vederstein (Jan 4, 2018)

Brian,

If your willing to wait several weeks, ebay vendors from China sell low cost timing pulleys.

I find it amazing how it's possible to buy something direct from China that's only a few dollars and it costs the buyer nothing to ship.  Somebody is subsidizing something.

...Ved.


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## Brian Rupnow (Jan 4, 2018)

I may have to take a different approach here. I just priced out an 25A30 sprocket and a 25B72 sprocket . A minimum length of #25 roller chain (10'-0') and a masterlink  from Canadian Bearings, and that comes to $183.00. Cowabunga!! This is making old bicycle sprockets look much more appealing.


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## Brian Rupnow (Jan 4, 2018)

The answer to it all-May be hanging on my wall---This chain and sprocket set was used on one of my old models, which was later scrapped and all the useable parts saved for another project. This is #40 chain, and a bit too heavy for the compressor project. however, when having to make a choice between $180 and something I already have, I can be easily swayed.


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## bjo (Jan 4, 2018)

Brian Rupnow said:


> Thank you, Shopshoe. Mine would work better if I changed a pulley and sped it up a bit. People want to see the balloon pop.--I'm always glad to hear from someone who takes a bit of pleasure from what I post.---Brian



In the video, I was hoping the pressure got high enough to pull the balloon off the compressor output and fly about the room.


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## Brian Rupnow (Jan 4, 2018)

bjo said:


> In the video, I was hoping the pressure got high enough to pull the balloon off the compressor output and fly about the room.


Actually it did once. That is why I have that big steel donut at the top of the balloon tube.--To prevent fly away balloons. (The balloon tube puts me in mind of the C N Tower in Toronto.)


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## Brian Rupnow (Jan 4, 2018)

Not much to show for a days work, but progress, none the less. I have two more tiny valve parts to make, then a bit of silver soldering and Loctite work.


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## Barnbikes (Jan 4, 2018)

Brian - Used to use a program called sprocketeer (free download) when I made bicycle sprockets years ago. Pick your chain size and the tooth count and it would design it for you.

http://www.idleamusements.com/?page_id=54


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## Herbiev (Jan 4, 2018)

Hi Brian. We could use a few balloons of cool Canadian air down here in Oz. 41 degrees C this weekend


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## Brian Rupnow (Jan 4, 2018)

Barnbikes--I didn't look to far into the link you sent me, but it appears to be for cnc machining. Both of my machines are manual.---Brian


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## Barnbikes (Jan 5, 2018)

Brian
It lets you save in G-code or dxf form.


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## Brian Rupnow (Jan 5, 2018)

Today I learned something that I will share with you. In the typical ball and cone valves that I build, you will see a cross-pin directly above the red ball, to prevent the ball from getting sucked up to block the orifice above it. For seven years now I've been working on a four foot length of this 1/16" diameter round rod, and today I used the last of it. I called every metal supplier that I know, and nobody carries 1/16" diameter cold rolled rod. The only source I could find was the local hobby shop, and they have 1/16" diameter music wire.  This has a very nice finish, but is harder then the devils horn and damned near impossible to cut with a hacksaw, band saw or even side cutters. I can't remember where I got the original piece of 1/16" material I've been using this past seven years, but it probably came from the hobby shop also. That doesn't pose a terribly big problem---the stuff cuts easily with a 1/16" wide abrasive cut-off wheel in my pneumatic grinder. Since it is so terribly hard to cut, it is difficult to cut precisely measured lengths of the rod for cross pins. So---I cut them a bit long, Loctite them in place, and then "hopefully' be able to trim them to length "in Situ" without marking up the brass housings they are Loctited into. I will let you know how that goes tomorrow.


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## Brian Rupnow (Jan 5, 2018)

A quick question--Is there any easy way to remove Loctite residue from brass, other than physically scraping/sanding it off? I doubt that there is, but people on the forums continue to amaze me with the things they know and I don't.---Brian


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## Herbiev (Jan 5, 2018)

To clean up cured loctite I use Loctite 768 X-NMS Cleanup Solvent


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## Brian Rupnow (Jan 6, 2018)

Here we are with both rod end valves in place. The biggest trick in making these things is to be able to Loctite the pieces together without getting any Loctite on the steel ball.---This is an acquired "knack". Both valves have been tested by the good old primitive "suck and blow test". One thing I might mention--If you ever make any of these valves, a secret to making them leak-proof is to set the part with a cone on a good solid steel surface (not wood), set the ball into the cone, then hit the ball a good solid "whack" with a hammer. This will ensure that the line contact at the ball/cone  interface really does conform to the shape of the ball. Not a light "tap", but not such a heavy blow that it distorts the overall shape of the brass cone part. This too is an acquired "knack". As I mentioned earlier. the 1/16" ball keeper pins were longer than necessary, and stuck out on each side of the brass valve assembly. This was solved in part by some careful filing, then the assemblies were set up in the lathe 3 jaw chuck and spun at 200 rpm while I did my magic with a strip of 260 grit cloth which blended in the ends of the 1/16" pins and also cleaned up any Loctite residue. Then a carefully applied circle of J B weld and the valve assemblies were slid into the holes prepared in the aluminum end caps.   Now its a matter of waiting 24 hours for the J B Weld to cure, and hoping like heck that none of it drooled down into the air hole in the bottom of the port the valves are fitted to. I'll know in 24 hours.


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## ShopShoe (Jan 6, 2018)

Brian,

For your 1/16 rod, I think Drill Rod would work better than the music wire. A quick search showed it available in 1/16 from several suppliers I use, but I'm in the USA. This is just FYI, as it looks like you're rolling along just fine on the present build. Did I mention that I like to follow your adventures in machine and engine building.

--ShopShoe


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## WSMkid (Jan 6, 2018)

Any possibility of annealing your music wire?
Watching among the rest. 
GJ


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## Brian Rupnow (Jan 6, 2018)

I bought a 3 foot length of 1/16" music wire at the hobby-shop yesterday, but have found out since that I can buy 1/16" mig wire which is supposedly "soft" compared to music wire. Will check that out with my welding gas supplier on Monday.


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## Brian Rupnow (Jan 6, 2018)

I think it was Chris over on MEM that asked how I was going to plumb these new valves into the main header that feeds the balloon tube. I will drill and tap it for the two green "spigots" and then use some clear flexible tubing to tie the valves in.


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## Ghosty (Jan 6, 2018)

Brian,
You can get 1/16" TIG welding wire which is soft.

Cheers


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## Brian Rupnow (Jan 6, 2018)

Thanks Ghosty I will try and buy some of that on Monday.---Brian


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## Brian Rupnow (Jan 6, 2018)

Some good news this evening.--The J.B. Weld has set up sufficiently that I was able to give the compressor a test spin by hand this evening, and both of the new valves are operating  as I had hoped. Now as the pistons move in the cylinder, they are pumping air no matter which way they are travelling. This should effectively almost double the volume of air pumped for every 360 degrees of shaft rotation.


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## Brian Rupnow (Jan 7, 2018)

SUCCESS!!!! Today I finished the second set of valves on the model compressor so it would be double acting and proceeded to make a video of it blowing up a balloon and bursting it. I used my Rockerblock engine this time, because it has a slightly larger pulley on it than my overhead cam engine. In the first video, the balloon got bigger, and bigger, and bigger but refused to pop, and I figured anybody watching might go to sleep before it burst, so the first video link is a technical fail.--Second time around, I set up the tripod for my digital camera, put a new balloon in place, opened my office door so I wouldn't gas myself, and started the engine and then got out of the way and let it run. Great success with the second video!! You can see that I was able to use an o-ring drive belt and avoid buying a costly timing belt drive set-up or using a sprocket and chain that would have been to big for the job. You will see however that it's right on the ragged edge--the pulley actually stops and the belt drive slips momentarily during each revolution.
[ame]https://www.youtube.com/watch?v=-_iqt3ecAZc[/ame]
[ame]https://www.youtube.com/watch?v=cTBajAJrRnU[/ame]


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## stragenmitsuko (Jan 8, 2018)

Waay to go :thumbup:

Here's a thought : 
An IC engine is also a kind of compressor . 
Why not connect the exhaust of the engine to the intake manifold of the compressor , and  see if it makes a difference . 

Pat


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## ODgreenK5 (Jan 8, 2018)

Won't work on a positive displacement compressor. Too much back pressure for engine to run correctly.


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## stragenmitsuko (Jan 8, 2018)

Yes I know backpressure could  and most likely will be an issue . 
Most certainly on a two stroke , possably less on a four stroke . 

And  the balloon pressure should be no more then a few fractions over 
atmosferic . 
So , who knows .... worth giving it a go ?


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## werowance (Jan 9, 2018)

i recall a kit for old farmall tractors where you pulled out a spark plug and screwed in an air hose so that you could inflate a tire.  this kit was for a super A I believe that's a c113 engine 4 cylinder.  wonder in scaled down version how much pressure could be achieved doing that?

hate to take a way from Brians original thread here.  wonderfull machine you have made.  I like it.


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## Brian Rupnow (Jan 9, 2018)

Sparkplug pumps were a pretty common automobile accessory in the 1950's. My first air compressor was an old 1 cylinder Briggs with a sparkplug pump driven by a washing machine motor.


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## Cogsy (Jan 10, 2018)

I still have one in my shed, although the rubber hose has perished quite a bit over the years so it probably wouldn't work any more. Still can't bring myself to throw it away though, it might come in handy for something...


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## Brian Rupnow (Jan 12, 2018)

This is something really neat to see--Engine, running compressor, running steam engine.
[ame]https://www.youtube.com/watch?v=Z0ANwIiTTAg[/ame]


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## Charles Lamont (Jan 12, 2018)

"Will the compressor pump water?" He asked, mischievously.


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## Brian Rupnow (Jan 12, 2018)

Charles Lamont said:


> "Will the compressor pump water?" He asked, mischievously.


Yes Charles, it would.--But first you have to promise to come over and clean up the mess.---Brian


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## Foozer (Jan 12, 2018)

You're having way to much fun . .


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## ShopShoe (Jan 13, 2018)

It IS pretty neat, Brian.

I have really enjoyed this project.

--ShopShoe


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