Ray Hasbrouck #4 Cylinder and Piston

[Nerdz]

The plans for the engine call for the Valve to be made out of steel and the Valve Body out of Brass. The plans also call for the main Cylinder to be made out of steel, and the main piston to be made out of 2024 Aluminum. From what Ive read I shouldnt use Aluminum on steel for any of these parts, (unless this is not true). What materials should I use? Ive read that Cast Iron is best and 12L14 is OK.

I would think that anything steel exposed to steam would rust rather quickly and seize the engine. What about Aluminum on Aluminum?

 

[toolznthings]

Hi,
I run mine on air so this might not apply, but I used bronze ( 660 )for my piston and steel for the cylinder. I also used a light fit o-ring on the piston to keep the friction low. Mines 2x size.

 

[Nerdz]

It does help and I may have came to my own conclusion; it seems that engines that are meant to run on steam have Cast Iron Cylinders and Aluminum Pistons. Ray even suggests further on that C.R.S Cylinders/Pistons may be used for moderate use. Hmm I guess since we are doing models, Al on Al would probably work for air. I would like to get one running on steam though, but my Jewelry supplier doesn't have silver solder in stock yet.

Ive also read (here on the forums) that Cast Iron Piston rings would also suffice with a Aluminum/Steel Piston.

 

[deverett]

Conventional wisdom suggests that where two metals ae in constact, either sliding as in a piston/cylinder arrangement, or bushings, then dissimilar metals are to be preferred. (with the noted exception of cast iron running in cast iron). Generally, ali against ali is not recommended.

Whether you use steel or cast iron for the cylinder is of lesser importance. Cast iron rings work well in steel or cast iron cylinders with an ali piston.

Dave
The Emerald Isle

 

[Philjoe5]

Chris,

Al on Al would probably work

This is a bad combination and can easily gall. When it does, you'll have two parts "welded" together.

Dave said it while I was typing but it's worth repeating

Full sized steam engines have cast iron pistons in cast iron cylinders. This is one of the few cases where identical metals can be used for these parts. Cast iron rings are typical as well.

For models I have used brass or bronze pistons in cast iron or CR steel when running on steam for over 4 years quite successfully.

For models run on air, I've used brass pistons in aluminum with good results. Some of my models with this combination have over 300 hours on them with no signs of any problems.

For both steam and air powered engines I've only made cast iron piston rings a few times. Mostly, I cut 3 - 5 grooves about 0.005" deep in the piston that hold oil quite well. Making CI piston rings is not difficult but takes a little practice.

Cast iron and steel used in steam engine cylinders and pistons remains rust free providing a good quality steam oil is used, I've run some of my models and also working steam engines at our museum for years with no evidence of rust. A coating of good steam oil provides rust protection. I don't strip these engines down after a steam run, just a shot of steam oil at the end of the run to keep them rust free.

I hope this information is useful and best of luck on the #4 build. I'm a great fan of Ray's engines. They will run trouble free for years

Cheers,
phil

 

[Nerdz]

Thanks Phil and Dave!

This is exactly what I was looking for, I was mostly correct in my assumptions. I havent ever machined cast iron before, but Ive been told I have to use carbide bits and its very dusty. I still have another engine ahead of this one to make, but its always nice to prepare ahead of time.

For CR Steel what alloy should I use? Onlinemetals doesnt sell 12L14 in square but they have 1018 steel.

EDIT: seems the same metal place where I am going to get Cast Iron sells 12L14 in Squares. But is there a preferred alloy?

 

[RonGinger]

For a small engine like the #4 alloy is not really important. Its not like you are looking for 100k miles of use. I'd get whatever I had in my scrap box, or the simplest supplier to deal with, then the cheapest material.

 

[Philjoe5]

Cast iron is often cut with carbide. This is because when cast the outer surface may be chilled, ie, harder than heck. So carbide will get through that.

OTOH if you're cutting continuously cast iron, trademark Durabar, it won't have that problem and HSS will do fine. Sometimes (!) if you buy CI from a supplier and they sell it in 13" lengths, it's Durabar.

Cutting CI is dusty, but good CI is great to work with. It cuts well, finishes nicely, and threads easily. I'm spoiled by Durabar because there is a distributor near me that sells me the drops for scrap prices.

Cheers,
Phil

 

[Nerdz]

Luckily I have some brazed Carbide Bits I bought for steel.A HSS bit just sits in my lathe because thats what I use most of the time. Oddly enough I just "winged" the angles when grinding and found out what works best. Its the Best way to learn from what I was told.

Now can the valve be made out of the same Piston Combos? ie CI -CI or CRS-CI, etc

 

[Philjoe5]

I like to use bronze - CI or brass - CI for the valve - seat combo. However, in restoring an old working engine, I noted they had used a CI valve and CI seat quite successfully. Those guys knew a lot more than I do.

Cheers,
Phil