Joint Project - Building two little Elmer #25 engines

[raynerd]

My brother-in-law has always been into engineering and was brought up building cars with a current job in designing and fitting large scale pipe work. Many years ago he did try and build an engine of his own design but he didn`t have the tooling and eventually gave up. Since building up my selection of tooling he has become more and more interested in getting involved and about a month ago I gave him that old lathe I bought a while ago ( although wish I hadn`t as I in retrospect I could have salvaged some damn useful pieces for future projects from it, including the motor  ) - http://madmodder.net/index.php?topic=1083.0

He has done a great job of building it up, he has refitted all the frame work around a thick steel base and it is now very solid and with a little more tuning, should be capable of some accurate work. Anyway, we decided to do a joint project and after I showed him Spuddevans (Tim) smashing job of the Elmer #25 engine, we both agreed we would try that one. Not only do we have the original Elmer plans for free but we also have Tims excellent write up and pictures. As we both wanted an engine at the end of it, we decided that we would split the parts and a double up. As I have the milling machine I ended up with the Frame, cylinder and piston and he took the flywheel, crank and base/foot (round like on Tims rather than square as per plans).

Anyway, we are on our way, here are all the bits minus the base. There is something extra satisfying about having duplicate parts! Not too much further to go, frame obviously needs marking out and drilling but then it should be a case of putting it all together! I`ve put some oil grooves on the piston this time and I think with my more accurate machining, the pistons are a better fit than on my previous engine. The brass cylinder also drilled and reamed much much smoother than the ally on my last one - infact even after drilling it was a mirror finish on the inside. Certainly a satisfying "POP" when the piston is pulled from the cylinder. All parts need polishing and buffing.







I was just wondering - is it a possibility that a joint engine could be organised on the forum or does this not interest anyone?

Chris

[Bernd]

Great work there Chris.

As far as joint engine building as a forum project. I don't know. BrassMachine is involved with it on the HMEM forum. Personal opinion, I don't think it works out to well. Many are enthusiastic at the begining but that seems to start dimming as the project goes on.

Take a look here http://www.homemodelenginemachinist.com/index.php?PHPSESSID=3afc95ce84e01615c8bde7c2951f6698&board=24.0

regards,
Bernd

[kvom]

I joined in the TB2 project on HMEM.  So far I received most of the necessary parts, and once I finish the paddleduck engine I think I will just try to complete it by fabricating the few parts remaining, esp. now that I have some beginning knowledge of silver solder.

[spuddevans]

Looking very good there Chris 

It's funny how making 2 of a part only takes a little more time than making 1 part. There's something to be said for production techniques.

I look forward to seeing more pics and even a video of them running.


Tim

[sbwhart]

Looking good Chris

I can see the effects of the learning curve you went through with your first build on these parts, Its nice when you can bounce ideas off another person when doing projects like this, I supose thats the strength of Forums like this.

Have fun

Stew

[raynerd]

Tim - I`ll take plenty more pics but your embarrass me with how amazingly clear they are! Talking of a video - have you taken one of your yet?

Stew - I couldn`t have done half the processes that I am now learning without this forum -    I asked tones of questions when I first joined but it was all so overwhelming - key skills, milling, drilling, turning, marking out...etc are a little tricky to source the basics as you guys tend to ask more advanced questions on forums - not the basics. I think you only truly appreciate and begin to understand these skills when in practice in the workshop.

It was my first attempt at silver soldering - the steel screw into the brass cylinder was no problemo however when putting the steel pin into the ally crank I ended up melting and warping it! Is it just a case of being careful or is there some way of preventing this from happening.

All the best
Chris

[sbwhart]

Chris

Silver soldering in ally is a no no, the best way would be high strength loctite.

Stew

[raynerd]

Ahh - would make sense - the crank totally lost its shape. I`ll know for next time.

Just as a little extension - would it be possible when complete to turn these back to back - join the cranks of both onto either side of one flywheel and off-set the pistons so it would be working as a twin cylinder engine. Just an idea?  

[Bernd]

Chris,

Something like this perhaps?



This is Elmers #9 H Twin.

Regards,
Bernd

[raynerd]

Haha - fantastic, Bernd! It is basically exactly what I described, infact Elmer 25 design back to back!!

You know the off-set, I`ve been thinking about this and is it quite simply set so that when one piston is out and at the furthest point on the crank the other will be at its lowest point? - 180 deg. I`m sure I read somewhere that is was 90deg off-set but I can`t get my head around that.

Chris

[Bernd]

Chris,

The piston and stroke are different between the #25 and the #9. The #25 Wobbler has 3/8" bore and a 1/2" stroke were as the #9 H Twin has a 1/4" bore by 3/8" stroke.

Check your PM in a few minutes. I have something for you.

Bernd

[spuddevans]

Talking of a video - have you taken one of your yet?

I did make one, it's linked from my build thread, but here's another link Clicky

Tim

[raynerd]

Well all was going so well this evening- however I had snapped a 1.5mm drill bit going down the frame for the air intake as my final hole to be drilled   The frame will have to be remade but me being impatient and wanting to know if this little engine runs, left the plugged up hole and redrilled from the top. I counter-sunk and tapped M6 and then drilled the centre from a M6 bolt and used this as my air intake. This allowed me to at least put the parts together and see if it runs. The frame can be remade for aesthetics later - the air intake doesn`t look particularly good on the top side of the frame!

I put all the parts together, turned on the compressor and I nearly had a heart attack - it run without any problems. A bit sticky to get going but was perfect when it was running. I played around for a good 5 minutes and it ran smoother and smoother - went to get my camera, was just about to turn it on and "pop" bits fly everywhere. The silver solder had worked free from cylinder and pin - the spring propelling everything for added effect!

Well it ran ... then it stopped and exploded - but at least an immediate success. I can at least sleep knowing that another few days of cleaning, polishing and re-soldering and we`ll have a couple of working engines.

[sbwhart]

Well done 

Its a runner
 


Stew

[raynerd]

For a short time at least! Clearly my silver soldering needs some improvements.

Chris

[raynerd]

Well my little engine is up and running. The other one is just having some finishing touches - we snapped a drill bit in the port hole

I`ll post a couple of pics when they are both up and running together but for now here is my unpolished engine.

Thanks for all your help, that is engine number two under the belt ...

Chris