Tiny I.C. Engine

[gbritnell]

Hi Gail or Arv,
I have downloaded the plans and notes and have gone through the entire post but I couldn't find what size wire you used for your valve springs. I probably missed it but if not could you post it?
Thanks,
George

 

[cfellows]

I don't typically like to build model engines this small, but there is something about this one that keeps pulling me back. Hmmm, wonder if a hot tube engine this small could be made to work...

Chuck

 

[putputman]

George, I probably didn't post anything on the spring as I used some springs out of my collection. I save every small spring I find and also buy some of those spring assortments you get at the junk stores.

The exhaust spring can be anything the actuator can operate. The intake spring has to be as light as possible and still moves the valve closed. I rely on the compression against the valve head to really seal the valve. As one old timer told me, "you just need enough spring pressure to keep the flies out".

Hopeful Gail or Kel can give you better information than I did.

 

[kcmillin]

George, I too used a spring I had on hand. I believe it came from an X-Mod R/C car from radio shack. I purchased a package of an assortment of tiny springs. I used the lightest spring, and trimmed it so it was a loose fit with the valve closed.

I would say the spring wire is between .012 and .018, and about 4-5 coils. I am going to try some guitar strings to make some springs The Deanofid way.

Shown Here
http://www.homemodelenginemachinist.com/index.php?topic=8253.0

Kel

 

[GailInNM]

George,
My intake spring is 8 turns of 0.009 music wire wound on a 0.078 mandrel. Finished OD is 0.115. Free length was set to provide about 0.05 compression with the valve closed.

My exhaust spring is 8 turns of 0.012 music wire wound on 0.078 mandrel. Finished OD 1s about 0.115 also.
I started off with 0.011 wire, same wind, but changed it as I thought I was getting some valve float at high RPM.

I did not do a post winding heat treat on them.

Arv was kind enough to send me two of the springs he used for the intake. It was an extension spring that he then stretched out. I measured it at 0.012 wire size and 0.152 OD. I ended up not using them as I wanted to use an1/8 spring keeper so they were larger in diameter than I wanted.

If your, or any other Tiny builder needs some wire to make the springs, I have 1 pound coils of those sizes and other sizes near them that I bought at machine shop auction that was going out of business 20 years ago. I have not used more than a few percent of any of them so I have enought for many lifetimes of building toys. I will be l glad to spool off 10 or 20 feet and drop them in an envelope and mail to people with US addresses N/C.

Gail in NM

 

[littlefold]

Gail,
Do you buy your metal online?
If you do who do you use?
I'm having some problems with my online metal supplier.
It has taken a long time to ship.
If anyone can give me a good source I would appreciate it.
Thanks guys.
Tim

 

[gbritnell]

Hi Gail,
Thanks for the offer. I dropped you a note.
George

 

[GailInNM]

Tim,
You asked about metal suppliers a few days ago. I have built up a good stock over the years so don't have to order too much any more. If I need a foot, I normally end up ordering 3 feet so I have some on hand.

If I just need a little bit of common 360 brass, 6061 Aluminum, or CRS, I have a Metal Supermarket about 10 miles away. They are expensive but no shipping and I can have it today. They don't have mush in the way of my preferred materials. I like 12l14 and 1144 steel. 2024 and 7075 Alum for conrods and pistons and the like.

When I do order however, I shop around a little bit as prices vary wildly between suppliers, and some have cutting charges and some don't. Others get to you on shipping. So I do comparison shopping.

My favorite on line suppliers are:
http://www.speedymetals.com/
Best for cast iron and have a good supply of specialty metals. One of the few online places that have cast iron below 1 inch diameter. Also have small diameter 12L14 for building small toys. Quick shipping.

http://www.onlinemetals.com/index.cfm
Quick shipping, but watch out for their cutting charges. They have a weird way of calculating them.

http://www.metalexpress.net
I have used them a couple of times, but recently thier prices have seemed to increase more than average. Multiple warehouses and not all of them stock everything. Just have to check that everything is coming out of the same warehouse to keep shipping costs down.

Some times you can get good buys on ebay for screw machine remnants, but most of the commercial suppliers of stock sizes on ebay are expensive.

Everything changes from week to week, so you have to check them all out.

Gail in NM

 

[putputman]

Tim, another place to buy material, tools, etc. is McMaster Carr. I consider them a very good supplier and buy most of my stuff from them. They are not cheap, but they handle good stuff.

The biggest problem I have with them is they use UPS for shipping and shipping can kill you. I hold off on my orders until I have enough to spread the shipping cost over more material & tools.

They also have one of the better catalog Webb sites. It is easy to navigate & zero in on what you are looking for.

When you start getting near the end of your build, I have some extra springs, plastic tubing, & Viton o-rings I can send you. Just let me know when you want them.

 

[stevehuckss396]

The biggest problem I have with them is they use UPS for shipping and shipping can kill you. I hold off on my orders until I have enough to spread the shipping cost over more material & tools.

I have always found MCMC to be one of the more reasonable on shipping. The shipping is not figured on any orders. After you order you are charged actual shipping cost and is usually less than I figured.

 

[gbritnell]

Being that Arv, Kel and Gail have posted there Tinys in one thread I hope that they won't be put off by me adding some of my build. If this thread is getting too crowded I can start another with no problem.
Anyway for those following this thread there has been a great deal of interest shown by Chuck, myself and a few others so being that I like to build small this was right up my alley.
Here's my first part, the cylinder head. I went with iron for the material. I had read that there had been a little bit of a problem with arcing from the plug to the rocker arm/post so I changed the angle of the plug port. I am going with an 8-32 plug so the thread was also changed. For the intake and exhaust ports I threaded them 8-32 also. This way I can make my inlet and exhaust pipes and thread them into the head. And last but not least I added about .047 material to what would be valve guide stem extensions. Having seen the videos of the others running I don't know that this is a necessary change but if they add too much friction I can always cut them off. When I turned the head I left extra stock and then spun the bosses on my rotary table.
Ok. on with the pictures.
George

 

[kcmillin]

Nice Work George.

I think you picked the perfect place to post your pics. This thread is turning out to be an incredible wealth of knowledge, and should make making the engine easier for others, plus a plethora of variations and improvements. I would imagine that Arv is one proud pappy.

I love the extensions for the valve guides.

Probably a good choice too, My exhaust valve guide is wearing from the rocker arms sideways influence. I am going to make roller rockers for my inline to hinder this from happening.

Kel

 

[cfellows]

You're off to a great start, George. Can't wait to see how your flavor turns out, given the unbelievable work you've done on other engines.

Chuck

 

[GailInNM]

Come on in George. Arv is throwing a great theme party.
Looking good.
Gail in NM

 

[putputman]

Glad to have you on board George. It is unreal how many variations can be made in a 3/8 diameter bore. Looking forward to watching this build.

I'll bet Chuck is trying to figure out how he can use bearing balls & magnets in his build. He is a master with those items.

 

[NickG]

This is a great thread, will be the first place I look when building my first i.c. thanks to all :bow:

 

[gbritnell]

I got some more parts made this morning, the piston, pin and connecting rod. I went with bronze for the rod so it would serve as a good bearing surface. I cut a little recess in both sides of the rod to make up for the weight of it versus an aluminum rod. I also went with 1-72 screws to hold the rod cap on which will offset the weight.
gbritnell

 

[littlefold]

Thanks guys,I have placed my order.

That looks great Gbrit.
When you go in from the side for the spark plug do you first drill a straight hole all the way through?Then drill from the side to meet the hole?I guess you would just plug the top hole?
I am trying to get this.
Looks great so far.

Tim

 

[gbritnell]

Hi Tim,
I'm not quite sure what you're asking but here's what I did for my spark plug hole.
As I mentioned, one of the fellows said that they go a little arcing from the plug to the rocker assembly and looking at the pictures I can see why, the plug is very close.
I looked at the original design and laid it out in my CAD program. I changed the port that enters from the combustion chamber side so that it has 5* on it. I went in about .160 from the shoulder of the drill. I then set up the head so that I could come in from the outside and indicated it square to the bottom 2 screw holes. I then rotated it 38* from vertical and tilted it back 48*. This gave me a perfect intersection with the first hole. I then counterbored the hole to about .200 dia. until I got a nice flat surface and then tapped it 8-32.
If anyone is building 'Tiny' and would like a drawing of this revision please let me know and I would be glad to provide it.
George

 

[Metal Butcher]

Hi George, I see that you are off-and-running. I can't wait to see your version in person!

I really like that you're building a project that I can relate to and accomplish myself in the near future.

Hi Tim, Are your referring to the optional spark plug side-entry shown in the full size plans? I looked at the "plugging" idea and will probably drill from the bottom of the head (combustion chamber) to intersect with the threaded side entry location. It should work, although "plugging" is not at all difficult. I prefer the idea of a side location for the plug on the full size version. Plenty of room that way with out being near at the busy top end of the head. On the 'Tiny' version I'll likely play follow the Leaders!

-MB