[Jeroen]

Originally Posted by Sutripta

Two stroke. So I would think premix.

You would think so, but you would be wrong!

If you read Jan Ridder’s design specification/consideration he specifically designed this little two stroke engine to run short periods of time, no or very little load and no need for any kind of lubrication.

His guidelines on the carburator are to use regular car fuel (euro 95) or cole fuel. Which is sort of a camping burner type of petrol. Used by hard core camping types!

So no premix, no oil, just fuel and no lubrication!
I do wonder, the compression ratio of this engine is just about 1:5 and it is supposed to run fine on Euro 95? Time will tell. Whatever, I am confident that i will get good compression and therefor good end compression temperature. I also have a ready made spark plug, so let’s see what happens. As it is, my next challenges are milling the fly wheel, machining the driving rod and the supports. Lots of worries. In fact I am not worried about lubrication at all. I will. most likely, run this little engine once or twice only. Just so I can show the world I made a DIY engine that runs!

Jeroen

[Sutripta]

Originally Posted by Jeroen

You would think so, but you would be wrong!

If you read Jan Ridder’s design specification/consideration he specifically designed this little two stroke engine to run short periods of time, no or very little load and no need for any kind of lubrication.

Without lubrication, short period is what it'll run for, whether by intent, or by force!

If someone has one of those el cheapo model airplane engines, and is willing to further the cause of the curious, could he pls, run it without lubrication and let us know the results.

Sutripta

[Jeroen]

Originally Posted by Sutripta

Without lubrication, short period is what it'll run for, whether by intent, or by force!

As it is, I am just concentrating on getting to a stage where I could actually see if it will run at all! I have yet to find anybody that actually made it that far. I have met a few guys on my Dutch forum who sort of finalised all the machining/fabrication, but never got it to run.

We will see, still lots of machining and milling to be done!

Jeroen

[Sutripta]

Originally Posted by Jeroen

I have yet to find anybody that actually made it that far. I have met a few guys on my Dutch forum who sort of finalised all the machining/fabrication, but never got it to run.

That's disheartening. Did you know this before starting on the project?

Sutripta

[Jeroen]

Originally Posted by Sutripta

That's disheartening. Did you know this before starting on the project?

No. It was remarkable difficult to get some proper advise/insights into the various designs out on the internet.

The DIY model engine build community is quite small. Some of the fabricators are probably much better at machining than being on the internet. (it might be an age thing?)

So in practice there is only a limited number of people that you can check/talk to. On my Dutch model build forum there are really only 5-7 people posting on regular basis, including myself. Some people pop up only once/twice a year. And 99% of what is being discussed are steam engines, not two/four-stroke engines.

The volume of steam engine enthusiast seems to outnumber the volume of 2/4-stroke enthusiast by a very large margin. Currently on the (steam) engine forum there are two guys that are posting about their ongoing projects. Me and Ruud, they guy that also did the soldering course. Ruud is currently building a hit/miss engine. He was going to build a Debbie also, but somehow as I announced to go the Debbie way, he decided to do something alternative.

I checked specifically if I could post on the Steam section, there is no dedicated petrol engine section. They were fine. A lot of the posts are about machining and tooling rather than steam (or Petrol) specific.

I have a dedicated Debbie thread on the Dutch forum. I have had the odd comment from other builders who tried to get Debbie to run. One even shared a photograph of the finished model and told me he could not get it to run. I asked him some more questions, but never got any replies. He seemed to have disappeared again.

Jan Ridders is one of the most prolific engine designer and builders. And his design/drawings are very clear. Which is very important to me. And he offered to help, if I ever got stuck. I have emailed him a few times and he always responses within 24 hours.

Mind you, I would not be surprised if there are quite a few guys out there that can’t get their steam engine to run either! Running a steam engine on compressed air is pretty straight forward and allows for quite a few ‘imperfections’ on finish, tolerance and so. But start running it on steam and a whole host of potential problems will pop up.

I am happy fiddling along. I am (re) learning a lot. The advise I get from the few other guys on the forum tends to be very good and constructive. They have helped me a lot, send me parts, materials, tools etc.

I am in no hurry, I will happily re-make parts if I have to (as I already did). Reading through Jan Ridders notes and advise on Debbie and how to get her to run, I feel I might succeed ultimately. But if I don’t, that is not the end of the world either. I will think up a new project and just start all over again. And I might still revisit Debbie now and then to see if I can get her running. It’s the same with my cars; I have one small outstanding issue on the Jaguar. When I bought it, it was there. In all these years I have never been able to fix it properly. I must have spend at least 100 hours trouble shooting it. Again and again and again. It is just a small annoying little problem. And I am just as happy doing a few more hours trouble shooting as I was when I had a go at it the first time. It’s not always the result that counts. Just doing something you enjoy, takes away your mind from other problems, is just as important.

In all honesty I was quite surprised to see my wobbler run as smooth as it did! That was a nice bonus!

Jeroen

[Sutripta]

^^^
Guess you'll have to think on the lines of 'my car won't start'!
What is the carburetion and ignition principle in this case?

Sutripta

[Jeroen]

Originally Posted by Sutripta

^^^
Guess you'll have to think on the lines of 'my car won't start'!
What is the carburetion and ignition principle in this case?

Let’s cross that bridge when we get there! Basic rule of engagement is that everything is highly suspect since it is all DIY made by old git getting back behind a lathe after 40 years. !

Not sure if I shared this before, but there is an English version of Jan’s description. Have a look at the video too!

http://ridders.nu/Webpaginas/pagina_...t_frameset.htm

to your earlier comments on the lubrication:

Quoting Jan:

This material is more or less self-lubricating due to the relatively high carbon content and the thermal expansion of this material is very low and equal for the piston and cylinder. Together with the fact that this material is very wear-free and has no tendency to seize, jamming of the piston in the cylinder never occurs despite the absence of a forced lubrication system.

Lets hope we get to test that theory! Fingers crossed.

Jeroen

[Thad E Ginathom]

If it runs... that will be a big win, and I'm sure you'll be running it as many times as you have friends you can coax into the workshop for a demo! And I'm sure they'll be rightly impressed.

If it doesn't run... It is still a win, for the [re]learning and experience gained. And, as you say, something fiddle with until, one day, maybe, it does run.

Keep up the good work!

[Jeroen]

Have not had much time to spend on Debbie. But at least I got a few more goodies. Next part I will be making is the driving rod. I check my drills and reamers. It will require a ø8mm and Ø11mm hole. I have got a 7,8mm and 8mm reamer. But not a 10,8mm drill or a 11mm reamer. So Saturday afternoon another trek to HBM. In my W123, might as well use it for a few more weeks, till it comes of the road again.

HBM doesn’t stock 10.8mm drills! I did get the 11mm reamer. And a few other goodies. Some flux for my soldering and a few very simple, but handy tap holders.



Also, another telescopic holder for my micro-dial.



This coming week, I aim to spend some time on Debbie!

Jeroen

[Jeroen]

At long last some time to spend on Debbie.

As shown earlier, I spend a lot of time honing the piston/cilinder and also ensuring that the piston rod ran smoothly through the glide bearing.

What I forgot to do, was to assemble it all and sees what happens:

Well this is what happened when I tried to put it all together:



When I tried to assemble the cylinder, piston, piston rod and the bottom plate, it would not fit properly

Took a bit of measuring to figure out what was wrong: Here is the problem: The piston rod is not perpendicular to the bottom of the piston.



Nothing that can be done about that. So I quickly made a new piston. Done in under an hour! Next drilled the hole and tapped the thread. For good measure I decided to put the tap straight into the chuck.



End result was perfect!



I cleaned out my workbench a bit. I was getting fed up with all the bits of material falling all over each other, chips and stuff getting in between. Sorted now!





Next job is to redo the fork. Hole/thread was crooked on that as well!

Jeroen

[Jeroen]

Tonight I started on the new fork.

I had done this once before, so it all went pretty smoothly.

The drawing, the old part and the piece of brass I will be using.



Rough cut, just with the hack saw



Fixing the clamp on the mini-mill. Not super critical how it lines up, so I just use one of the 90º angle hooks.



This piece of brass is already exactly 10mm wide, so squaring off one end with the mill



Turn it around, careful measuring and squaring off the other side. Close enough



Next, to make it overall square I had to take about 1mm off.



Now to get that hole exactly in the middle:



Auto centre punch to the rescue. One of my most useful tools I have bought!



I modified my little tap follower. I based it on a drawing from the Internet as one of my very first project. Never gave the exact dimensions to much thought. But it won’t fit in the Mini Mill. So I modified it on the spot! Maximum collet size on the mill is 10mm







Careful measuring and positioning so I can drill the perfect hole





And now for my next trick: First use of my tap follower, worked pretty good!



So far, so good, fork fits nicely on the piston rod! Still a bit more milling to finalise it.

[Jeroen]

Steady progress. I am managing a few hours work on Debbie almost every evening this week!

Having squared off the part for the fork, I managed to drill and ream a very precise hole



Some more measuring and prepping for the final cuts:



Back into the mini mill; I am using a 4 mm finger bit. The driving rod will be 5mm thick, so after the first pass I will still need to mill 0,5 on each inside of the fork teeth.



Everything together, looking good. I ordered a new tap which will allow me to thread deeper in both the cilinder and the fork. It really needs another 3mm of thread. But for now this is looking good. Very happy with it.



Next, the driving rod. I still had a 6m thick brass plate. So out comes the old hack saw again for the first rough cut.





Pretty rough shape still!



Some months ago when I was having problems with my mini mill finish, a member of my Dutch Model forum made a simple fly cutter for me and send it to me. I had not been able to use it yet. But here goes:





With the same feed I tried a few different RPMs. This first pass is a 0,2mm deep cut at 280 RPM



With the same feed, I doubled the RPM and I think the finish is slightly better:





The thickness is right on the money and the fit into the fork perfect!



Next, I drew out the rod outline. First thing is to get the two centres for the bearings positioned in the correct place. Everything else lines up to these two.





I have not yet decided how I am going to produce this piston rod. I have some ideas on how to fabricate the curved outside along the bearings. I will have to make a simple tool to allow the part to rotate underneath the mill.

More to come

Jeroen

[Thad E Ginathom]

A nice chapter!

It's all good, but I often find some small thing will impress me: I think your hacksaw skills are awesome!

I'm pretty impressed with the marking out on the brass plate too.

Well done, both machine and handwork.

[Jeroen]

A wet and windy Sunday. So perfect day to spend in my garage fiddling with stuff. First cleaned and fixed my bicycle. Spend most of the day with Debbie. Made some good progress.

First thing I needed was a little tool to allow me to rotate the driving rod underneath my mini mill. I found this boss I used on my Wobbler engine.

So I drilled two 6mm holes into the driving rod. A few spacers and a nut and Bob’s your uncle. Ready for some perfect circular milling.









Not bad for a first attempt! Pretty pleased with this.



I started with the large circular part (12mm) as I thought that would be easier. Next the smaller one, (8mm). I had to modify some existing spacer rings on the lathe, so the would be only 7,5mm diatemeter.



Worked a treat!







Next milling down the side, first a few quick heavy cuts.



Move the rod again and finish it very carefully with a smaller diameter cutter, so I get a nice smooth transition from the circular part into the flat section of the rod.



Voila, my very first driving rod!!





Next to drill out the two holes to the correct diameters. The first one is 8mm, so I drilled 7.9mm and reamed with 8mm. Done! But then I hit a snag, the larger hole is 11mm. I have a 10.9mm drill and a 11mm reamer. But I forgot my mini mill chuck won’t take anything over 10mm!!

So I tried to get it clamped down in my lathe, but no way, too small, too odd a shape.



So I need to figure out how to drill these 11mm holes. Maybe I can turn down the drill and reamer? Not sure, that is very tough steel.

Back to an earlier problem; the internal thread of the piston and the fork. I received a new tap, specially for blind holes. On the drawing on the Internet it looked as if the cutting action of this tap was more forward to the point then on my regular tap. But not really.



So I just grinned it down by about 4mm



That did the trick just fine! Looks much better now:



Jeroen

[Jeroen]

This evening I wanted to finish the drive rod. Which meant milling down the drill bit so it would fit into my mini mill

So here goes:

I decided to use my four jaw check to get the best accuracy:



Now, look at this for perfect alignment!

https://www.youtube.com/watch?v=PqbKZw77bl4

End result:



So I drilled the hole with this 10,8mm drill. The 11mm reamer happened to have a 10mm end, so it fitted into my mini drill after all. But when I fitted it another problem materialised!

https://www.youtube.com/watch?v=z6jxA-BPSgA

Brand new, but bend! So I need to return it. So not much I could do, but to fiddle about with some other parts, checking a few things. That did not improve my mood as I found out I made a mistake on the cylinder head

The drawing calls for a M10 hole in the middle to fit the spark plug. But I have drilled it with a 10mm drill!



I have made this mistake several time already. These thread tables are becoming increasingly more confusing for my marbled mind, unfortunately. I can’t figure out inside versus outside thread, muddle them up and this is the result.

Either I make a complete new cylinder head, or I drill it out to 12mm, put M14 thread into it and make a bushing with M14 thread outside and M10 on the inside. I just checked I don’t have the correct tap for the spark plug anyway. I have two sets of M10 tap and die, but they have different pitch. This needs to be M10x1

I don’t have the material to redo the cylinder head. I would have to re-order. But as I need to go back to HBM to exchange the reamer, I might as well get the taps/die I need and fix it all in one go.

Jeroen