Elmer’s #5 Geared Engine . . . maybe

[bmac2]

Ok back in the saddle. I made up the spacers that go between the front bearing mount and the ring. These are just ¼” aluminum rod drilled to fit 2-56 screws and parted off. The only thing I had to change was the length as the gear I’m using is thicker than the one called for in the plans. I got everything mounted up and I guess this is where the fun begins. I had my doubts that this would work “out of the box” and it didn’t. It looks like “Piston rod screw must be exactly centered between two teeth” works when you use the prescribed gear but this is going to take some fiddling.



On the up side the hole for the piston rod screw looks to line up with the little tit on the shaft left by parting it off so that’s on the plus side. I am very glad that I used Loctite instead of silver soldering here. A little heat and the two pieces separated cleanly.

The parts count is going up and looking in the box somewhere along the line I made the eccentric strap.

 

[stragenmitsuko]

Looks like the movement is straight allright , just not parallel to the base .
I guess a little tweaking of the ring and or the orbiting gear ought to take care of that .

But look on the bright side , the gears do mesh and don't bind .

 

[bmac2]

Hi Pat, I think if the gear was any freer it would drop right into the sloppy category but that might work in my favor. I’ve been messing around with it on and off for the last couple of days and started by rotating the orbiting gear counter clockwise one tooth and from there just playing around with the positioning of the gear arm. I think I’m getting close but finding the sweet spot is touchy. The tolerances between the gears, gear arm position and the height of the cylinder mount on this thing are tight.

 

[Iampappabear]

I have been "tinkering" with a geared engine between working on my serious projects and came upon the same issue of ring gear. Part of the intent was to use as many parts as possible that were lying around in my shop so my solution is to use a timing belt glued inside a ring. The inner gear is just a stock timing sprocket. Looks promising but having problems finding the best adhesive for rubber to aluminum.

 

[a41capt]

Not sure about the type of rubber, but I’ve always had good luck with 3M premium weatherstrip adhesive for rubber to all metal bonds. The stuff is ugly looking, and we always called it “monkey snot”, unless they’ve cleaned it up recently.

If the belt is silicone based, there’s damn few things that will bond well with it though...

 

[bmac2]

Hey pappabear. I’m with you. I try not to lay out too much hard cash on my hobbies unless it’s tooling. I can’t see any reason a timing belt wouldn’t work so long as it’s a 2 to 1 ratio and you can keep it on the center line. I’ve had good results with Permatex Plastic weld attaching nylon standoffs to aluminum for electronics project but it STINKS! Where it says “Well Ventilates Area” it means middle of the back yard with a wind.

a41Catpt In my experience with rubber adhesive the more it looks like “Snot” the better it works.

For me it’s going to drive me nuts. It feels Sooo close but I just haven’t found that sweet spot. It’s not bad but I still have some binding between 3 and 6 o’clock.

 

[bmac2]

I am going to rename this thread “Elmer’s #5 Geared Engine . . . YES” and dropping the maybe. The gear arm was a snug fit on the gear, so I could rotate it. By just tweaking it a bit each time and trying it I couldn’t hit the spot. Then I put a couple of dial indicators on the shaft and cylinder block and notices that the cylinder was lifting at the end of the stroke. Then I started using feeler gauges as shims under the cylinder, and by trial and error found the sweet spot. I but a drop on crazy glue on the gear arm to hold it in place, drilled it and used 3 bins to mount it to the gear. To my relief when I got things back together it still runs free with no appreciable binding.

 

[Rockytime]

Very interesting. I started the geared engine perhaps at least 25 years ago. Life sometimes gets in the way like other pursuits. At just a couple of months away from 80 there are several things I no longer do. However, this is kind of a reminder that I should perhaps pick it up this winter. Sitting in a basement in the summer won't cut it. You have done very well. Elmer's engines are always interesting.

 

[bmac2]

Wow Les it looks like you have all the big pieces done and what you have looks great. If you haven’t made the valve rod yet I can strongly recommend building it up rather than making it out of one piece. Winter is coming sooner than I think any of us want and around here we can start seeing snow in October. Ok except for Australia and the rest of the southern hemisphere then I guess winters almost over yay.

 

[bmac2]

Now that I have it dialed in I know how tall the cylinder “foot” has to be and after the match (congratulations to France and Croatia) I got it milled to size and drilled for the mounting screws.

This is the part I was tempted not to post.

But . . . .

With the foot made I got the engine assembled and roughly timed. I couldn’t feel any binding so I hooked up the air and the piston slammed to the end of the stroke and stopped. I played around with the eccentric for a while but it wasn’t going anywhere.

It was time for a tear down to see what was going wrong and this is where things get a bit embarrassing.

Now earlier in this thread I had to fix my DRO, so I have digital read outs on my mill. I have shown a couple of CAD drawings and I have used a CAD or 3D CAD system for over 25 years. So how did I manage to mess up the 9 holes in the valve plate this badly?

I’ll make a new one tomorrow but maybe l should use a ruler, punch and a hand drill.

 

[bmac2]

I got the NEW valve plate made and spent a couple of hours listening to an audio book while lapping both sides on the surface plate (Chinese Thom stone). Then once again got the engine assembled and roughly timed.

Oh Mr. Verburg what had you eaten the night you dreamed this up?

The timing is way off and it’s drenched in oil, running rough but the little SOB does run. I can’t for the life of me think why I left that shaft so long but now I just have to get the timing set, clean it up and do some fit and finish.

 

[minh-thanh]

Wow... that's nice !

 

[stragenmitsuko]

congratulations , beautifull job .

 

[Cogsy]

That is a cool engine. Congrats.

 

[justintime]

Your end mill has a 1/4" shank which is not common for the holders. Make a holder from scrap round 1018 or what ever you have . Bore the hole slightly less than .250. Then ream the hole to .251. Turn the outside of the blank to fit an endmill holder you do have, I used 3/4" because I rarely use that holder. Turn the work to .749. Mill a flat for the set screw on the holder, drill and tap for a setscrew for the 1/4" endmill. Much better than using a drill chuck.
The holder will have less runout than most drill chucks. You need as close to no runout as possible with tiny endmills.

mike

Hello, not sure if I grasp exactly what you are suggesting, but I would advocate for buying holders for such tiny end mills. I was fortunate enough to have them supplied for every size imaginable where I was employed during my machine career so I have a drawer full of all sizes from ( 1/16" to 3/8" ID ) all with 3/8" shanks. They are not pricy to buy, have hardened and ground shanks and they run dead-on. Just something to consider before investing too much time in making one ( or more ) which will not run as perfectly as a purchased item. Luck !

 

[bmac2]

Well I’m calling it done. To everyone that dropped by during this weird adventure, Sergulbka, Anatol, TonyM, Rudy, marioserafica, a41capt, kwoodhands, stragenmitsuko, aka9950202, nel2lar, Brian Rupnow, Iampappabear, Rockytime, kvom, Cogsy, minh-thanh. I’d like to say thanks for the encouragement and motivation to keep up the posts.

There that done and before this thread turns into a “Chick Flick” some last pics of the engine.
The first thing I did was cut that shaft to length! Then to finish it off I wrapped the cylinder with some walnut veneer for lagging held in place with some 1/8” wide brass bands. It turns out that I was correct when I said that the flywheel might be a little light. At its slowest speed the flywheel is almost coming to a stop at each end of the stroke but I like the look and I don’t think I’ll change it. In the second last picture you can see one of the pins I put into the gear arm to keep it in position. I’ll post a final video of it in “Finished Projects”

 

[kvom]

You did a great job with this. My only suggestion would be to replace the slotted screws with model scale hex screws,

 

[bmac2]

kvom I would have to agree with you. I am not a fan of slotted screws at the best of time. When I came across the ring gear I also found a box of those 2x56 SS screws. If this was a model of an actual engine I would have at least swapped them out for cap heads but it’s more of a novelty and with the two big slots in the drive end I decided to just leave them as is. But in the end I’m just happy that it runs and it is fun to watch

 

[natalefr]

Super engine

 

[Nigel C]

That is a beautiful engine. Many thanks for sharing both the journey and result.