# Inverted Hit n Miss Engine, Compressed Air



## cfellows (May 15, 2011)

Got started on the build this weekend. The uprights are formed from 3" x 3/8" thick hot rolled steel, each 6" tall. Most of the work was done with my metal cutting bandsaw and vertical belt grinder.  I did use the milling maching to clean up the edges and form the inside radiuses at the top and the bottom. I've included pictures with two different flywheels. I'll probably use the larger, 7" cast iron fly wheel that I had originally planned for but also kind of like the smaller, 6" brass flywheel that I had milled from solid several years ago. I guess I'll keep the option open until I get further along.






















Chuck


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## metalmad (May 15, 2011)

An elegant start Chuck :bow:
Pete


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## cfellows (May 15, 2011)

Thanks, Pete.

One more picture, I forgot that I had finished the cylinder several days ago. The lump of aluminum the cylinder is sitting on is just to show how it will look with the cylinder head.






Chuck


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## Dave G (May 15, 2011)

My how I love scratch builds, this thing will keep me interested. Very nice Chuck, Dave


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## cfellows (May 18, 2011)

Thanks again, folks for all the encouragement and positive comments.

I decided to do the base a little differently than in the original picture. I had planned to use quarter sections of steel pipe to create a cove moulding like I did with the radial. Instead, I'm using 3/8" thick angle iron. I picked up a piece of 2" x 2" by 26" at my local metal yard, brought it home, and cut it down to the size I needed, 1.375" x .625". The bandsaw made this job easier, but it was still a bit tedious to rip it down, not to mention a little hard on my arm muscles keeping the pressure on the feed. Next the piece will be cut down to the proper lengths with 45 degree angles to form miter joints on the ends. The 5/8" leg will be on the bottom, with the cut edge out to form a kind of cove. The base will have 1/4" thick steel plate welded on the top so the total height of the base will be 1.625"

Here's a picture of the base pieces






And here's a drawing with the governor and the new base






Chuck


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## kcmillin (May 18, 2011)

Great project Chuck! I love how you incorporate IC characteristics into air engines. It really makes then unique. 

That brass flywheel looks great, I don't think I could ever get the first cut done on such a large piece of brass, too nervous. :big:

Kel


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## Brian Rupnow (May 18, 2011)

Looking very good Chuck. I will be watching this one.---Brian


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## cfellows (May 19, 2011)

Thanks, Brian. No issues with valves that won't seat on this model!

Here's some more pictures of the base taking shape. These are probably not interesting to all of you, but thought I'd show them anyway. So far I have about 5 hours into the base alone.

This is just a pic of me using an indexable cutter to smooth the bandsawed edges.






This is just two views of the lashup on my bandsaw to cut the 45 degee mitre on the first end. The angle iron is mounted upside down with a spacer indexed against the back of the built in vice. Another spacer is used underneath to raise the workpiece high enough that the clamps could find purchase on a flat spot on the back of the vise. C-Clamps are used to hold the work rather than the adjustable portion of the built in vice.











These are pictures where I'm cutting the 45 degree miter on the other end. Here, the angle is right side up.











Getting the pieces cut to exactly the right length was very challenging since it was hard to project where the blade would intersect the base of the cut. Exact length wasn't really important anyway, but getting the opposing sides the same length is important if you want a square base with tight mitre corners. So, I used a stop block clamped to the back of the fixed vice jaw to make sure the matching pieces were the same length.






Here's a few shots of the frame assembled but not yet welded. Outside dimensions measured around the bottom of the base is 5.75" x 6.75". The height of this part is 1.375". The thickness of the angle iron is 3/8".
















Now I can cut out the plate that will form the top of the base.


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## cfellows (May 19, 2011)

Here's a couple more pictures.

The first picture is the base dry fitted with the top. The top is made from 1/4" thick cold rolled steel, 5.5" x 6.5"






And, here is the first of 2 pictures of the parts I finished so far, dry fitted.






And, a second picture with the soda can for scale.






Chuck


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## mklotz (May 19, 2011)

Tell us, Chuck... What's it like to never sleep?

Seriously, looking great, as always.


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## cfellows (May 19, 2011)

mklotz  said:
			
		

> Tell us, Chuck... What's it like to never sleep?
> 
> Seriously, looking great, as always.



Thanks, Marv, high praise indeed coming from you!

Well, I do have to sleep, but being retired, I don't have to work, as long as I can stay below the significant-other's radar...

Chuck


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## maverick (May 19, 2011)

Another nice build Chuck, very elegant. But take it easy will ya. You're making us guys with day jobs look bad.

Regards,
Mike


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## Chaffe (May 20, 2011)

looking very traditional, and heavy! brilliant


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## cfellows (May 21, 2011)

Thanks for the comments, folks... always appreciated!

Here is the magic that will make the engine operate pretty realistically (I hope). It's a quick release valve that I discovered in an airgun book. It uses air pressure from the air source to quickly open the valve when the cam rotates to the cutout. In the airgun world, the trigger mechanism releases the valve. Either way, the 100PSI air source should exert a pressure of about 5 pounds on the air valve, more than enough to open it quickly. This first picture shows how it all works in a drawing with description.






And here are the pieces that I've made. The valve body is made from 3/4" brass rod and the valve is 1/4" drill rod.






And this picture shows where the valve body sits on the engine base






Chuck


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## ShedBoy (May 21, 2011)

Wow Chuck that looks great. Can't wait to see this one running!


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## bearcar1 (May 21, 2011)

Oh I do like the way that base turned out for you Chuck. And kudos for showing us how it was done. Were you a cabinet carpenter in your previous life? Those mitered corners really turned out quite well. Thm: And BTW, you must stay very low under the Mrs.' radar to have enough time to accomplish all of that in such a short time. :big:

BC1
Jim


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## Brian Rupnow (May 21, 2011)

Well Dang!!! I'm sure glad the world didn't end afterall---I would hate to have missed this build!!! Chuck, about 20 years ago I was involved in a research project on pneumatic "Impact cylinders". They were interesting, and very scary whe they "fired". Imagine, if you can, an air cylinder with a double ended rod. the rod at one end is exposed in the normal fashion, but at the other end, the rod passes thru an airtight gland into a second chamber which is filled with high pressure air at 100 to 150 pounds. To fire this cylinder, low pressure air is admitted to the back side of the piston, and the piston rod begins to extend the way you would expect. Then about half way thru its stroke, the back side of the rod pulls out of the gland seperating the low pressure side from the high pressure chamber and all of that high presure air in the high pressure chamber floods thru the now open gland in a big rush, driving the piston the rest of the way thru its travel like a cannon. I think that is similar to the way pneumatic nailers work. The force (impact) generated was beyond belief.---Brian


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## b.lindsey (May 23, 2011)

Looking wonderful Chuck. Just a great design all the way around...certainly looking forward to seeing it run...which won't be long at this current pace...lol

Regards,
Bill


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## cfellows (May 23, 2011)

Thanks, Bill. Hopefully I can keep up the momentum.

I'm into the fiddley bits now so progress will probably be slower and not very exciting. I had decided to use 3-48 SHCS to fasten the two halves of the valve body assembly to the base. However, after I drilled and tapped the holes, I found that my screws were too short. So, I made some brass screws from a piece of hex rod I had on hand. Screws turned out nice:






But, when I tried to tighten them down, I promptly twisted one off. Guess brass was a bad idea in these small sizes. So I drilled out the holes and tapped them to 4-40. Had the right size screws on hand and screwed the valve assembly to the base:











Next I started on the timing gears. The small gear is made from two pieces, the gear and the hub. After the gear teeth are cut, the gear will be bored out, then loctited or hard soldered to the hub / collar. Here I've turned the gear blank and the hub at the same time from a piece of 1" 12L14.






Next I'm parting off the hub:






Here's a picture of all the gear blanks. The large timing gear was turned from cast iron and will have a pitch diameter of 1.5". The small gear is mounted on a mandrel, ready to have the teeth cut:






Today's work will include cutting the teeth on the gears and getting the smaller, primary gear assembled into one piece. Then, it's on to the cam.

Chuck


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## cfellows (May 23, 2011)

Here's a couple of pictures of the gears. The first picture shows the primary gear set before assembly.






And here's a picture showing the large timing gear and 2 copies of the small timing gear with hub. The one on the left shows a pitiful attempt at silver soldering. I used too much solder and got the assembly too hot. This resulted in solder flowing into the valleys between the teeth. I tried to dig the solder out but no luck. Now I know why they call it hard solder! The assembly to the right is put together with loctite 620. It will probably hold alright... at least I've not had it fail on any of my applications yet.






Chuck


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## Brian Rupnow (May 23, 2011)

Chuck---Its good to see someone who solders like I do!!! ;D ;D What gear cutters do you have? A complete set or------


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## cfellows (May 23, 2011)

Brian Rupnow  said:
			
		

> Chuck---Its good to see someone who solders like I do!!! ;D ;D What gear cutters do you have? A complete set or------



Hey Brian... These are cut with 24 pitch involute gear cutters. I think I lack 1 or 2 from having a complete set of 24 pitch. I've bought them 1 at a time as I needed them. Expensive buggers!

Chuck


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## cfellows (May 23, 2011)

One last picture for today. Got the cam finished and attached to the large timing gear.


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## maverick (May 23, 2011)

Chuck- What material did you make the cam from? Will it be hardened? Just wondered if the follower will 
round over the edge or if that will even matter.

Mike


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## cfellows (May 23, 2011)

maverick  said:
			
		

> Chuck- What material did you make the cam from? Will it be hardened? Just wondered if the follower will
> round over the edge or if that will even matter.
> 
> Mike



The cam is made from 12L14. I don't think round over will be a problem.  Since it's a hit n miss engine, the cam follower will only be on the cam about 10% of the time. 

Chuck


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## cfellows (May 31, 2011)

Managed to get a few more things done. The governor is patterned after the one Phil Duclos used on his Victorian engine. I made the 5/8" brass balls using an over-the-top ball turner that I had made several years ago. Before I could use it however, I had to adapt it to my QCTP. I used the boring bar holder and inserted a 3/4" brass bar that I had bored out to 1/2" to accommodate the 1/2" shaft of the ball turner. The small protrusions on one end of each ball will be turned off and bored to accept the swing arms of the governor.






I also made the piston and the connecting rod. The latter is made from 3/8" thick x 3/4" wide aluminum. Finally, I also finished the crank disk but still have to make the crank pin.






And, here's a couple of images with a few of the parts loosely hanging in place











Chuck


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## steamer (May 31, 2011)

You can have faith in the 620 Chuck...just make sure it's clean.

That is all coming along REALLY well!  Keep it up!

Dave


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## stevehuckss396 (Jun 1, 2011)

Did you cut the gears? If so, they look great.


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## cfellows (Jun 1, 2011)

stevehuckss396  said:
			
		

> Did you cut the gears? If so, they look great.



Thx, Steve. Yes, I cut the gears using commercial involute gear cutters. The large one is cast iron and the small one is 12L14.

Chuck


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## ShedBoy (Jun 1, 2011)

Beautiful work as always Chuck. 

Brock


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## cfellows (Jun 6, 2011)

Thanks, Brock,

Well, I think I'm within a day or two of having this thing ready for a test run. It will take a little longer to get the governor bits all hooked up so it runs in hit n miss mode, but I should have all that part finished as well in less than a week, maybe by the weekend sometime. I'm really pleased with the way everything is turning out. I think this will be a nice looking and good running engine.











Got to get it finished, I'm already thinking about my next project.

Chuck


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## Maryak (Jun 6, 2011)

Chuck,

That is one very nice engine. :bow: :bow:

Best Regards
Bob


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## cfellows (Jun 9, 2011)

Thanks, Bob.

I got the engine running last night and made a number of improvements and tuneups today. Once I got it all together, there were several embarrassing problems that I had to correct. 

- The connecting rod was too long so the piston was hitting the head before top dead center. Had to mill a depression in the head and face a 1/16" off the top of the piston. 

- The connecting rod was hitting the side of the cylinder so I had to turn a bevel on the inside of the cylinder and turn the rod down to a smaller diameter.

- The valve travel was insufficient to open the valve, so I had to do some more machining on the cam. Also had to increase the dwell since the valve wasn't staying open long enough.

Today I corrected all that. I also added the plumbing to bring the air supply line out the side of the base. Now all I have left is to complete the governor and valve latching mechanism so it will run in hit n miss mode.
Got a video loading on youtube at the moment.

I will post the video as soon as it finishes uploading. Here are some pictures.














































Chuck


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## cfellows (Jun 9, 2011)

And here's the video...

[ame=http://www.youtube.com/watch?v=9xECJ4WTrf8]http://www.youtube.com/watch?v=9xECJ4WTrf8[/ame]

Chuck


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## dvbydt (Jun 9, 2011)

You've got us all hanging on the edge of our seats!

Edit - just seen the video - beautiful. 

Ian


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## arnoldb (Jun 9, 2011)

:bow: :bow: Very well done indeed Chuck :bow: :bow:

She runs like a champ - and that sharp exhaust note is really *really* nice!
I'm sure this engine will be even more of a winner in hit 'n miss mode Thm:

Pity it's Winter here in Namibia and my day job and the unusual cold are interfering with shop time...

Kind regards, Arnold


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## nfk (Jun 9, 2011)

Lovely engine Chuck! :bow: :bow:
You work amazingly fast, you completed the whole engine in about 2 weeks!
Thanks for sharing your work with us.

Norberto


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## stevehuckss396 (Jun 9, 2011)

Well it's offical Chuck!!! You da man!!


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## Dave G (Jun 9, 2011)

Very nice engine Chuck. Looks to be a good runner, Dave


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## Brian Rupnow (Jun 9, 2011)

Amazing stuff, Chuck. You get KARMA for this one!!!---Brian


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## Catminer (Jun 9, 2011)

Very nice design and build, it would put on quite a show on steam!
I love IC. but you have me thinking about a compressed air engine now.

 Peter


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## slick95 (Jun 9, 2011)

Nicely done Chuck...Very Very Nice :bow: :bow: :bow:

Thanks for sharing...
Jeff


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## lathe nut (Jun 10, 2011)

Chuck, sounds great looks great and loved the video, you sure built that fast, someday hope to make it to retirement so I can play in the shop all day, or until I get tired, are you going to post a drawing of the machined parts, thanks for the time you took to share with us, Lathe Nut


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## kcmillin (Jun 10, 2011)

Well Done Chuck! She really sounds great, and powerful too.

Kel


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## cfellows (Jun 10, 2011)

First, thanks to everyone for the appreciative comments. Always enjoy knowing people are watching. And, I do plan to post drawings for the engine after I get it finished.

I was drilling and tapping 2-56 holes in the brass governor balls today to hold the screws that the springs will attach to. Of course, on the second ball, the tap got stock and I broke it off trying to get it out. Still not sure why it stuck. Anyway, after a few minutes of muttering and resisting the impulse to throw the part across the shop, I got the torch out to heat up the ball so I could take it off and make another. After I got it off, I was standing there looking at it when it ocurred to me, why not just rotate the ball 90 degrees and glue it back on? So, that's what I did. I put the broken tap hole on the inside where it will probably never show any. 







Now if I can just drill and tap the holes without breaking a second tap... of course, I could always just rotate it 45 degrees and try again!

Chuck


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## ozzie46 (Jun 10, 2011)

I can't add much to what everybody else has said so I'll just say well done and I love the sound.  Thm: Thm: Thm: Thm:

  Ron


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## cfellows (Jun 10, 2011)

Here's another video, this time in hit n miss mode. It's hitting every 3rd revolution of the cam which is every 6th revolution of the engine. Since I posted this video, I've made a couple of changes. I opened up the inlet passages from 5/32 to 3/16". I think I have one more place, the hole in the side of the valve which is still 5/32 which I will check later. Now it's hitting about every 4th revolution. I'm also going to add an o-ring to the piston and see if that helps. But for now, it runs pretty good.

[ame=http://www.youtube.com/watch?v=hNC36MoBCyw]http://www.youtube.com/watch?v=hNC36MoBCyw[/ame]

Chuck


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## Chaffe (Jun 14, 2011)

well done mate, looks good! sounds very nice


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## dgjessing (Jun 14, 2011)

Looking good!


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