Tiny I.C. Engine

[GailInNM]

Arv,
Good to hear from you. Things good here. Vision continues to get worse all the time and really slows down building. Recovery from the stroke is progressing nicely. Some functions will never come back but overall I am doing quite well.

The compression ratio on my Tiny's (I have built several) is 5.2:1. I played with it some in the early days and found that I could not tell any difference in operation from 5.0 to 5.3.

The final version has a cast iron cylinder with a cast iron piston. They were lapped independently to 0.0002 clearance. The piston has several oil grooves 0.005 wide and deep plus a spreader groove near the bottom to bring oil toward the head from the oil cup. I only use about 1 drop of oil per hour now.

I am working on my Woolwich locomotive now . It is powered by a H-N-M Tiny. I will do a thread on it later after I finish detailing it some more. Currently disassembled for anodizing. Here is a video of it sitting at Idle waiting for the main line to be free. Idle is 3000 rpm with it hitting about every 12 revolutions.

Gail in NM
http://youtu.be/a-csJ3As7dc
[ame]http://www.youtube.com/watch?v=a-csJ3As7dc&feature=share&list=UUC8RZePnFk5KLNYzDoXI0lw[/ame]

 

[AussieJimG]

Hello,

I followed this thread with interest and have been trying (off and on) to build a Tiny. At present, I am having problems finding the best way to make the valves.

I have tried turning them from stock (a couple of different ways) and making them by silver soldering buttons onto the stems. Neither way seems quite satisfactory. I don't think I get the required accuracy.

Now I wonder how the experts did it. Any advice?

Jim

 

[GailInNM]

Jim,
Not that I am an expert, but here is how I make my valves. The first thing to recognize is that the entire stem does not have to be made accurately. The part of the stem that sticks through the head when the valve is fully opened can be a little bit under size as it never engages the the valve guide when running. Likewise the portion of the stem that is in the pocket when the valve is fully closed is of no concern as it can never reach the valve guide. So it can be under size or oversize a bit without affecting things.

In the case of "Tiny" valves this only leaves about 3/16 of an inch, about 4.5 mm, that has to fit the valve guide. This is a lot easier than trying to turn 3/4 inch (20mm) or so to a precision fit with such small diameter.

Here's how I made mine for "Tiny". I started with 1/4 inch diameter 1144 steel. I like 1144 for small valves as it cuts easily with a good finish. I use a VBMT (35 degree diamond shape) carbide insert with a 0.015 tip radius. I have a high speed lathe so I run it about 3500 RPM. That is not critical but is does speed things up.

Two things that are important are keeping the stock projecting from the chuck or collet tothe minimum to make the valve and that the cutting tool is on center line. I use a dial indicator to set the tool height. Because of small diameter of the stem a few thousandths high or low is enough to ruin your whole day.

The compound on the lathe is set to 45 degrees. My collet closer nose sticks out a little bit so it is easier to get the cutting tool into position than it would be with a chuck, but is possible with a chuck. Remember that a prime objective is to keep the minimum of stock sticking out of the collet or chuck. When this is not possible, you can start with a larger diameter stock like 3/8 or 1/2 inch and it it stick out some. In any case careful positioning of the tool post on the compound will be necessary.

Out of time tonight. I will detail the actual machining in the next post.

Gail in NM

 

[GailInNM]

Time to make some chips. By this time I know how much of the end of the valve stem can be undersize because it will never engage the guide in operation. In my case on "Tiny" it is about 0.275 to 0.350 inch depending of if it is an intake or exhaust valve. Face off the end and zero what ever Z axis measuring devise you may be using. Rough cut the undersize portion of the stem. As my stem's working diameter will be about 0.078 inch diameter I cut it to about 0.085 diameter then change tools and put the spring retainer groove in. I sometimes put the groove in later holding the valve stem in a split collet. Back to the turning tool and finish turning to 0.075, about 0.003 undersize. I use this turning operation to calibrate the cutting tool by measuring the diameter and setting my DRO or dial to match the diameter.

Now I turn the rest of the stem to my 0.078 nominal dimension. It should fit in the valve guide but can be a bit of a stiff fit as it will be polished down to about 0.001 loose in the guide. After the stem is turned I cut the valve face using the compound. I lock the carriage to keep any side force generating by the compound feed from making the valve face rough. I make several passes with the compound to eliminate as many tooling marks as possible then unlock the carriage and turn the head diameter long enough to allow for cutting off the valve.

With the turning operations complete, I polish the working portion of the valve stem and the valve face with silicon carbide abrasive paper, commonly known as "wet or dry", with some light oil on it. I start with 400 grit until the valve stem fits smoothly in the guide and the polish a little bit more progressing through 600, 800 and 1200 grit grades of paper. To polish I cut a narrow strip of abrasive paper and back it with a strip of flat metal. I normally use a 5 inch steel machinists rule. EVERY TIME you test fit the valve in the guide you must clean it very well so no abrasive paste from the polishing operation gets in the guide. If any abrasive becomes embedded the walls of the guide it is there forever. The only way to remove it is to ream the guide hole larger.

When I cut off the valve from the stock I normally leave it a little bit long and the finish it to length in a collet or make a split collet to hold it in a chuck.

Gail in NM

 

[AussieJimG]

Thanks Gail, sorry for the delay in responding, I have been in hospital for a few days (I am sure you understand the situation).

Your advice makes good sense and I will give it a go when I can get back into the workshop. Thank you again.

Jim

 

[naijin]

Very nice quote in russian, I believe the same applies when translated into english!! Ha1 Ha!....... well done

 

[rac37]

IMG_0043.jpgMy Tiny IC
Completed a few days ago. Really enjoyed the build as it was quite a challenge for me. Thanks PutPutman for all the plans and info.
Now to try and make running video.

bob

 

[GailInNM]

If the insides are anywhere as nice as the outside I am sure that it runs great. Great build. Thm:Thm:
Gail in NM

 

[rac37]

Thanks Gail,
I've enjoyed following a lot of your posts and have gained a lot of insite from them. My Tiny is pretty much stock build I still have to use electric start may need to fine tune the intake valve spring. Using 87 octane gas and a little wd40 oil. So far cooling not a problem. Recently replaced one of the crank bearings and went with a viton o-ring. Yep I screwed up the original bearing a few too many thou. big.

bob

 

[awJCKDup]

Nice build Bob, built one myself and love the little guy. Best free plans I've ever gotten. Waiting for the video.


John

 

[putputman]

Bob, that is a beautiful engine. I am delighted to still see some interest in the Tiny I.C.

You, Gail, John, and several others have taken my design way beyond what I ever imagined it would be.

 

[rac37]

Thank you Arv for the compliment and for posting the plans for this neat little engine. I've had several runs with it and each time seems to get better. Really an enjoyable challenging build. Now guess I need to find video software to post a video of it running. Thanks to all posters on this thread a lot of great ideas and guidance.

bob

 

[rac37]

Short video of Tiny attempt to start and short run. third attempt. Sorry for hand in the way gotta work on my videography skills next.

[ame]http://youtu.be/VdYvExRV3Jc[/ame] bob

 

[Graemep]

HI all tiny builder I just finished my tiny and here is my take on this wonderful engine .Many Thanks to Putputman for the excellent plans and build log .Also thanks to Gail for all his effort and willingness of information to help builders like myself to build tiny .

 

[bazmak]

Theres me thinking i was an engineer then i read this thread
and sink into deep depression.If only i had the skill and eyesight
Congratulations all you Guys

 

[rac37]

Wow, nice looking engine Graemep. Did you use conventional alum. piston with o-ring? Really a neat little engine.

bob

 

[GailInNM]

A very well executed "Tiny" Graemep. Looks great. Thm:Thm:

Baz: Remember that skills come from trying things you have never done before. Eyesight can be a problem but can be worked around if you work at it. I am functionally blind in one eye and am way below the minimum driving requirements in the other with the best corrective lens available. I just push myself and work slowly.

Gail in NM

 

[Graemep]

Thanks every one this was my first IC engine . It was a great little engine to build as there was so much information given on this thread especially all the information and posts by Gail .

Bob: Thanks your little tiny looks excellent to and No I did not use an o-ring I use Gail's method of cast-iron piston honed to fit the bore (no rings ) .

Graeme

 

[putputman]

Graemep, Congratulations on building your first IC engine. Tiny I.C. is not an easy engine to build. I'll bet we see a lot of I.C. engines out of you in the future.

I really like they way you displayed your engine on the piston. Is that lever on the back side for adjusting timing?

Looking forward to a video.

 

[Graemep]

Hi all, here is a video of the first run of my tiny IC (I hope).

Thanks Arv for your reply and yes the lever is for the adjusting the timing

[ame="http://www.youtube.com/watch?v=C2K6bineCDs"]www.youtube.com/watch?v=C2K6bineCDs[/ame]



Graeme