My modified build of "Chucks Single"

[Metal Butcher]

A minor delay on the arrival spring weather gave me the chance to start another build. I decided on cfellows single cylinder, referred to as "Chucks Single." I admire this engine for many reasons, this is an air powered {4- stroke} engine that has good style and proportion. What really pushed it to the top of my build list was seeing and hearing a video of it run.

Here's the parts I made so far, not that much but it's a start. The base is 1/4" thick 1018 steel. The frame sides and front are made from 1/4'' thick aluminum scraps assembled with 4-40 screws. The cylinder is round 1-1/4" fine grain cast iron with the addition of cooling fins as a cosmetic touch.

Rather than completely dropping my hobby until the fall of the year, I will continue making parts when the weather allows time indoors.

EDIT: The words {Hit-miss} have been replaced with {4-stroke} in the second last sentence of the first paragraph.

-MB

 

[cfellows]

Nice start, MB. Have you seen all the threads from here from different builders?

This version http://www.homemodelenginemachinist.com/index.php?topic=3732.0, built by (Edited) PutPutMan operates as a true hit n miss version, with a governor. Note that it is a "2 stroke" version, in that it has no timing gears and the cam runs directly on the crankshaft.

Although there have been several people who have built a 4 stroke version, I don't believe anyone has successfully built a 4 stroke version that operates in Hit n Miss mode. Dreeves was working on one, but I've not seen whether he completed it or not.

Best of luck, let me know if you have any questions.

Chuck

 

[Metal Butcher]

Nice start, MB. Have you seen all the threads from here from different builders?

This version http://www.homemodelenginemachinist.com/index.php?topic=3732.0, built by Superfast operates as a true hit n miss version, with a governor. Note that it is a "2 stroke" version, in that it has no timing gears and the cam runs directly on the crankshaft.

Although there have been several people who have built a 4 stroke version, I don't believe anyone has successfully built a 4 stroke version that operates in Hit n Miss mode. Dreeves was working on one, but I've not seen whether he completed it or not.

Best of luck, let me know if you have any questions.

Chuck

OH NO! Now I'm confused. I got the plans from the down load section of the forum. Am I building a 2 stroke or a 4 stroke, and is it a hit-miss?

-MB

 

[cfellows]

The original engine was a 4 stroke engine and was NOT hit n miss. It has primary and secondary timing gears which causes the engine to "fire" every other revolution. I had originally planned to make it a hit n miss engine, thus the reason for the download file name.

My drawings do not include any hit n miss or governor parts. Unfortunately, the plans also don't include any specific drawings for the timing gears, the cam, or the cam follower. For now, that part is left up to the builder, so the engine can be built as either a 2 stroke or a 4 stroke.

When Superfast built his version of the engine, he made a 2 stroke version then added his own governor design to make the engine operate as hit n miss. From a functional standpoint, it sounds the same as a 4 stroke hit n miss would sound. Actually, other than aesthetics, there is no reason to make the engine 4 stroke if you plan to add a governor and operate the engine as hit n miss. The thread by Superfast includes pictures and drawings of his engine which should make it pretty easy to duplicate.

Chuck

 

[Metal Butcher]

All is well! I'm back on track.

The video I saw WAS the one YOU posted.

So, I'm building "Chucks single" a horizontal 4-stroke air engine.

All I need to do is Edit out (hit-miss) in my original post.

Thanks for straitening me out Chuck. :bow:

-MB

 

[cfellows]

Hey MB,

Here are some other threads with pictures and videos that might help:

GailInNM's engine: http://www.homemodelenginemachinist.com/index.php?topic=2410.0

BretK's engine: http://www.homemodelenginemachinist.com/index.php?topic=2422.0

PutPutMan's & Superfast's engines: http://www.homemodelenginemachinist.com/index.php?topic=3732.0

Did I miss any?

Chuck

 

[Metal Butcher]

Out of necessity I made the cylinder head from two separate pieces of brass-stock brazed together. The largest piece I had on hand was a 1-1/2" hex. I think this helped to simplify the machining processes and shorten the construction time. After the lathe work was finished I could have cut off the cylinder head but decided to leave it attached temporarily. The hexagonal-shape facilitated the indexing used to drill the bolt-hole pattern. It also provided a handy way to hold the work piece for brazing and subsequent machining.

My decision to use a six-bolt pattern on the cylinder head was based on personal preference. This left very little room for the bolts used to hold the exhaust flange. To accomplish this tight squeeze I used a .160" radius along with the use of 0-80 screws. I will also make a reduction in the diameter of the valve since two of the bolt heads touch at it’s 3/4" diameter. These minor changes should not be a problem.

If you look closely at the cylinder head, the intersection between the two brazed pieces cannot be seen. Although it really doesn't matter since the valve will cover that area at the front and the cylinder will cover it at the back. I have a few ideas that will require minor changes to the valve assembly. I will be posting these changes as the build progresses.

-MB

 

[cfellows]

The two piece head is a great idea. Sure is a lot easier than whittling it out of one piece! Also makes me think of some other possibilities.

Chuck

 

[Metal Butcher]

I machined the exhaust flange with a short 3/16" pipe stub and a 1/8' exit hole. This was necessary to clear the close .320 radius dictated by the clearance issue I created using a 6-bolt head pattern. in addition the exhaust valve spring will be held captive by the base of the flange.

The .250" exhaust valve bore was lightly lapped to fit a precision ground .250" s.steel slave valve piston. This piston to bore fit turned out very smooth and should work well. The text that Chuck provides indicates that the intake and exhaust ports are open at the same time. This can also be seen in the drawing that shows both ports open 50%. Since the center-to-center of the ports is .375" This means that the exhaust piston length should also be.375".

I made two extra pistons, one .392' long and the other .442" long. This raises the question of whether either- or- both will work and what effect will they have on the way the engine runs?

The spring I have on hand is .240 x .020x .500 and will not work since it will not close the valve due to its short length. Will a spring with the same diameter and wire size but .750 long work? Or is there a specific wire diameter, length, or preloaded compression length required to make the valve function properly?

Looking ahead at the intake valve it looks like a E-9 E-clip is needed. Is this correct?, and is there a quick-trick way to cut its groove on the valve stem? .

Sorry no picture today. My picture guy is off on a road trip.

-MB

 

[cfellows]

MB,

The .75" spring should work fine. The .020" wire size sounds perfect.

I use e-clips in my valve stems. To cut the groove, I use a dremel tool with an abrasive cutoff blade. This is easiest to do if you can be spinning it in the lathe while you cut the groove. I usually cut the groove before I part the valve off the rod it's turned from.

The length of the sliding piston valve isn't critical. I doubt you'll see any difference in performance. The reason I originally used two holes with a slave valve that doesn't quite span both holes is so part of the high pressure air coming in would escape out the exhaust before it closed, giving it a better sound. In my later designs, I only use one hole and a ball bearing instead of a cylindrical slave valve. Seems to work and sound about the same and is less work.

You may run into trouble if your slave valve is too close a fit in the hole. The slave valve takes quite beating when the high pressure air coming in slams it against the exhaust assembly. Over time, it may flatten and spread on the outboard side.

Chuck

 

[Metal Butcher]

Hi Chuck, thanks for the help. I was concerned about ordering the wrong springs and being stuck with a non running engine on the day of assembly. Sounds like you already tried different springs and valve piston lengths. And your indication that the valve cylinder length is not all that critical is very reassuring.

I don't understand the valve slamming problem you mention completely. I'm a little concerned since my exhaust valve pistons are about .0005 clearance. Seems that the only contact the piston has on the outboard side is with its spring. Did you mean there's a slam on the valve side when the intake valve closes? And if so could this be averted by using a lighter aluminum slave valve piston and/or with a lighter spring?

Thanks for the tip using a Dremel to cut the groove! Makes my day! I was afraid the only option might be the $100. grooving tool system advertised in the monthly Enco catalog.

EDIT: I just came up with a simple solution to stop the mushrooming problem on the end of the piston. Why not just machine a step on the piston, say .030 x .030 on the offending end?

-MB

 

[cfellows]

MB,

Mushrooming might not be a problem, depending on how you are set up. On one of my engines, I had the exhaust spring recessed out into the exhaust manifold, so the slave valve would hit the exhaust manifold when the inlet valve opened. If the spring stops the valve, you probably won't have a problem.

Also, don't know how many e-clips you've installed, but be very careful not to cut the groove too deep or the e-clip won't stay on.

Chuck

 

[Metal Butcher]

MB,

Mushrooming might not be a problem, depending on how you are set up. On one of my engines, I had the exhaust spring recessed out into the exhaust manifold, so the slave valve would hit the exhaust manifold when the inlet valve opened. If the spring stops the valve, you probably won't have a problem.

Also, don't know how many e-clips you've installed, but be very careful not to cut the groove too deep or the e-clip won't stay on.

Chuck

I never had the opportunity to cut a groove for an E-clip. It will be a first time for me, and it sounds a little tricky.

However, I have successfully lost every one I ever removed! ;D

-MB

 

[cfellows]

The idea is to cut a little, then try it. Repeat until the clip will slide into the grove without forcing and with some spring action to hold it in place.

Chuck

 

[Metal Butcher]

I made the two halves of the valve body and some additional pistons that include a small step on the intake side. The extra step was added for peace of mind since the piston spring will slam the piston when the intake valve closes.

Rather than machine the intake valve seat integral with the valve body, I step down an additional .110" x .250 to accept a separate valve seat. This will allow me to experiment with various materials and various sizes of valve- to- seat contact area.

I went shopping locally to find the E-clip. I visited Harbor Freight, three hardware stores, an appliance parts store, two auto parts stores and a machine shop supply outfit. I found larger clips, smaller clips, and no clips, no one had the required 3/32" clip.

When I was directed to a far away hobby shop I headed home and ordered online. After this proverbial "Wild Goose Chase" I will be happy to pay for the shipping! The valve stem will have to wait till my spring and E-clip order arrives. I will be trying a few ideas of strange ways that it can be made. This will undoubtedly be interesting!

Oh, and the three guys behind the counter at the machine shop supply had a blank (what?) look on there faces when I asked for a 3/32" E-clip! They all said they never heard of one or knew what it was! GO FIGURE!

A quick dive in their dumpster netted me three sealed but stained .34 oz. containers of 24300 medium Locktite. Not bad, at least I covered my gas expense. I will have to add them to my list of productive places to visit ;D

If you act like you're a little crazy, they usually leave you alone. :big:

-MB

 

[tel]

From the 'Frugal Files' - a simple ring of stainless steel spring wire does the same job as an 'E' clip, only neater.

Just wind up a bit of continuous closed spring, 1 wire diameter smaller than the shaft on the ID. Clip off individual rings as needed and slip 'em over the shaft and along until they click into the groove.

 

[Metal Butcher]

From the 'Frugal Files' - a simple ring of stainless steel spring wire does the same job as an 'E' clip, only neater.

Just wind up a bit of continuous closed spring, 1 wire diameter smaller than the shaft on the ID. Clip off individual rings as needed and slip 'em over the shaft and along until they click into the groove.

tel. That sounds like a good idea. As a matter of fact I've seen it done that way commercially on the end of a starter shaft to hold the gear, and a few other places too.

Its too late now. Theirs a 100 piece box of 3/32" E-clips headed my way!. :

-MB

 

[cfellows]

You've been busy, MB!

Hey, I like the idea of those nylon valve seats. Those should seat really well.

I also like the six head bolts and valve body bolts. Adds some style.

Tel, I like your spring ring retainer. What size spring wire do you reckon would be good for a 3/32 retainer?

By the way, I've got e-clips down to 1/16", although my 65 year old eyes and fingers make it increasingly hard to work with such small pieces. I lose about half of them when they fly out of my needle-nose piers never to be seen again.

Chuck

 

[Maryak]

MB,

Very nice work. :bow:

Best Regards
Bob

 

[Metal Butcher]

My small parts order of springs and e-clips was just handed to me by a UPS courier!
I placed the online order at 1:45 PM yesterday and it arrived at 11:50 Am today. That's about a total of 22 hours. That's just amazing service from ENCO, with free shipping to boot! :bow:

I ordered a 10 pack of springs (#240-0568) for the slave exhaust valve piston, .240x .020x .750 and also a packet (#240-0569) 1.000 long just to be on the safe side and for future use.

I also ordered the elusive 3/32" e-clips E-9 (#325-2834) and also packets of 1/8" and 3/16" to have on hand for future use. These e-clips are a nicely made piece of assembly hardware. And they are very reasonable in cost. Small sizes are in the $2 -$3 range for 100 ct packs.

I was looking ahead earlier this morning at the crank dimensions, and again I'm lost, how to build the crank? I would prefer to braze a build up together but my last and only attempt produced 2 that were a little wobbly and a 3rd that I settled on but still not perfect enough to be satisfied with. Machining from solid is not a possibility due to lack of material and a thorough understanding of the cutter requirements.

When I looked at the drawings I downloaded there's two different views of the crank that are adding to my confusion. I don't have a lot of experience interpreting drawings, pictures work a little better for me, so I think I'll review all the previous posted builds.

EDIT" I just found a 3/8"x 1" bar of 1018 cold rolled steel bar 12" long!. Maybe tomorrow, and with a little more info I'll face this feared machining operation!

I,m heading down to tackle the valve stem.

-MB