Snow Engine

[dnalot]

Hi

After 4 steam engine projects I think I now have the skills to tackle an internal combustion engine. After looking at my options I have decided on building the “Snow Engine”, a model designed by Doug Kelley. I have purchased a set of plans in the form of a booklet titled “Build The Snow” by Doug Kelly, used for $12.

The engine is a tandem, double-acting four stroke engine. Bore is 1.058” Stroke is 1.88” The tandem cylinders power a single journal crankshaft with one connecting rod. The crankshaft is fitted with a 9” flywheel.

Starting with the cylinders. The cylinder assembly is made of two parts, a cylinder sleeve and a water-jacket, both are made of easy turning steel and silver soldered together.

I turned both parts to the rough dimensions and then silver soldered the parts together. Once the parts cooled I chucked the part in the lathe and bored the cylinder to the final size. Then the parts were placed on a custom made mandrel and chucked in the lathe where the ends were squared and the water jacket was cut to its final form.

Next I used the mill to cut the flat on the top and bottom of the cylinders. The top flat has two holes for the cooling water to exit the engine, the bottom flat has two threaded holes for mounting the engine to its stand. The other two holes near the bottom are for the cooling water to enter the engine.

Before setting the parts aside I honed the cylinders making them ready for fitting the rings.

Mark T

 

[dnalot]

Hi

So I have been busy reducing a 16” log of 2.5” diameter 6061 T6 aluminum into 11 parts for the engine. To keep all these parts in line they are each fitted to the next with a close fit and special care given to keep all mating surfaces parallel. In addition to these parts the four 1.25” thick plates that complete the water-jacket for the heads were cut from plate and turned to diameter.

The next step is to do the drilling and tapping required to assemble these parts together.

Mark T

 

[dnalot]

Hi

It was a bit nerve wracking but I managed to drill and tap all the holes without snapping a tap off. To aid alignment of so many parts I made the holes for the screws the same diameter as the screw. Surprisingly everything came together smoothly. I used an X-3 milling machine fitted with DROs for drilling the holes and tapping. I recently updated the mill with zero backlash lead screws so returning to the same exact spot was almost effortless. Almost all of the aluminum parts require further machining so everything is now coming apart. I will provide photos of all the completed parts before reassembly. This week I also made the shaft bushings and some fixtures I will use to ream the bushings for the piston shafts.

Mark T

 

[Herbiev]

Looking great so far.

 

[dnalot]

Hi

I have now cut the relief holes in the sides of the cross slide support and the cylinder coupler. And have cut the excess material away from the safety guard. I have deviated from the original by giving the safety guard a rounded end that looks more like the original. After that I completed the combustion chambers by drilling and taping for the spark plugs and drilling and taping for the valve assemblies. A few hours of sanding and buffing and the aluminum parts were ready for anodizing. I did a hard anodize so the parts have a slight green tinge but will be very scratch resistant.

The next step is to press in the bushings and ream them for the shafts.

Mark T

 

[kvom]

The machining and parts look excellent. I have heard that the Snow can be difficult to get running; it's quite a nice challenge for an IC engine.

 

[dnalot]

Hi

I have heard that the Snow can be difficult to get running

I have heard that, but there are videos of several Snows running well so I have confidence in the design.

Besides, I have a reputation of being able to start anything. It's all in how you grasp the ignition key.

Mark T

 

[dnalot]

Hi

So I have a new phone that I have been using to take photos with. Unfortunately, the removable sim card decided to take a crap and I lost all the photos of the past week. Now I would need a thousand words to describe what and how I did things.

I pressed in the bushings in each head and the cross slide. They were made about .003” tight so they would need to be reamed to size after being pressed in. I assembled the head on one end of the cylinder, inserted the reamer into the other end and then installed that head over the shank of the reamer. Once assembled I used a tapered guide that fit between the reamers shank and the bushing in that head. Using a hand drill, I reamed the bushing to the exact size of the piston shaft. After that I reversed the process to ream the head on the other end of the cylinder. That was repeated on the other head. After cleaning I assembled the parts onto a long section of drill rod of the same diameter as the shaft. After tightening all the screws, the shaft could turn but very stiffly. Through the holes the vales will be mounted in I oiled the shaft with some 600 lapping compound added to the oil. Using a drill, I turned the shaft at about 100 RPM and oscillated it in and out a bit. After about a minute the shaft started to turn with a uniform resistance. At that point I disassembled all the parts and cleaned everything. Again using the drill rod as an assembly gig I reassembled all the parts and tightened the screws. The rod turned freely and was smooth when stroked back and forth as it will in use. I then removed the shaft and replaced it with the two-piece SS shaft joined with a coupler. I then lapped the cross slide to the bushing using the piston shaft as a guide. I had been worried the cylinders would not line up property but as luck will have it everything is looking good. The designer had cautioned that cylinder alignment is critical to this model working.

So here it is the only photo I have, the cylinders with the shafts and cross slide in place.

 

[dnalot]

Hi

I need a lot of gaskets with very tight tolerances and a lot of very small holes for this project. So I bought a $100 plotter with a knife. Unfortunately, the software does not have an import feature so you have to use its primitive drawing tools. The results are well worth the expense and effort. The machine made quick work of cutting out 12 gaskets that fit perfectly. I’m going to get a lot of use out of my new toy.

Mark T

 

[ICEpeter]

Mark,
What is your gasket material and what is the gasket material thickness? Thanks.

Peter J.

 

[dnalot]

Hi

What is your gasket material and what is the gasket material thickness? Thanks.

It is a treated paper resistant to water and oil, .015" thick

McMaster Carr part number 9556K84

Mark T

 

[dnalot]

Hi

The plan called for steel piston shafts, but I had some SS rod salvaged from an old printer that was highly polished so I used that. I also used SS for the cross slide. The pistons were turned from aluminum stock to .003” over size. After the pistons were mounted to the shaft they were turned to the correct diameter. The rings were made from cast iron and placed on a mandrel to expand them. I heated the base of the mandrel red hot and as the heat worked its way up the mandrel the rings dropped off one by one with the desired gap. I then fit the rings to the pistons by honing their sides until they fit in the pistons ring grove. I turned a short tube with tapered walls on the inside to use as a ring compressor. With all the parts made I started assembling the parts checking to make sure there was no binding as I went along. With the rings, lip seals and bushings all dragging a little the rods can be pushed back and forth with my fingers but a little stiffly. I figure that is as it should be so I went ahead and painted the cylinders with a high heat paint that is a grey/brown color.

Mark T

 

[dnalot]

Hi

Took a little vacation, worked on some other projects and now I’m back to work on the Snow Engine. Time to tackle the crankshaft. The plan called for an assembled crank silver soldered together so that’s what I did. The shaft is drill rod .5 inches. The cheeks are leaded steel .375” thick. Crystal-Bond works great for gluing parts together for machining. It’s basically just a high strength hot glue. The way I like to do this type of crank is to ream the holes to the exact size as the shaft. And then ream again .001” over size but not quite all the way through. This keeps the shaft(s) centered in the hole and they tend to stay located while Silver soldering (brazing). I use a small round file to take away most of the tight part of the hole leaving three points bearing on the shaft. Before assembling the parts, I sandblast the area to be soldered. Getting the flux in the hole between the shaft and wall of the hole is important if you want a solid joint. With the parts assembled and the spacers in place I set the crank on end (not clamped). The open end of the joint is facing up; I then bring the temperature up evenly until the solder melts. A little more heat and the solder starts to flow, I add a little more solder to the puddle and using the heat I work the puddle around the shaft. I then move the flame to the bottom of the joint until a little solder works out through the gaps I filed in the tight part of the hole. With this side done I rotate the part while still hot 180 degrees and repeat the steps on that side. Let the parts cool to room temperature and then clean. Before sawing out the section of shaft between the cheeks I tuned the cheeks to final diameter and cleaned and polished the shaft. A 10 minuet swim in the chemical bath and everything turned black.

Mark T

 

[dnalot]

Hi

The pylon for the shaft bearings and the housing for the bearings are made of aluminum. I made one change to the original plan here. The water pump was to be a separate unit mounted near the water tank. It looked messy to me so I have designed a pump to be mounted to the pylon just below the crankshaft. The pump I will build later but the bearing holder and the holes for mounting the pump are in place. The aluminum parts were anodized before the bushings were pressed in.

Mark T

 

[Herbiev]

How did you do the anodising. It looks great

 

[dnalot]

Hi

How did you do the anodising. It looks great

I do my home anodizing in a 5-gallon bucket. There are 4 steps to the process. (so you need 4 buckets) Only the anodizing bucket needs to be large, to provide room for multiple parts without touching. The other buckets can be smaller.
1- degrease in a very hot slightly caustic digresser. 2- de-smut; buy from Caswellplating.com 3- immerse in dilute solution of sulfuric acid with a mild current running between the part and an anode (sacrificial aluminum sheet) + to the part. Sulfuric acid can be bought at the hardware store’s plumbing department. It is sold as a drain cleaner, it will normally be in a plastic bottle wrapped in a plastic bag so it’s easy to spot on the shelf, dilute 10-1. 4-seal the anodized part; again buy from Caswellplating.com. The total process takes less than an hour. I have been using the same setup for several years with only the occasional topping off of the solutions with distilled water. Once you get set up there is very little expense.
The only real expense is the power supply. A simple battery charger will work but a controllable power supply is better. I’m using a converted power supply from an old computer. For best results calculate the area in inches to be anodized and multiply by .05 to find the amps required using a 12-volt supply. 10 to 20 minutes does the job.
If the part is polished, you tend to get a bright shiny part. On the snow engine I have buffed and then rubbed the parts down with a scotch-bright pad to give a softer finish.
Aluminum wire can be used for suspending the parts in the buckets, but you can only use the wire once. It will become anodized and will no longer be able to make electrical contact between the wire and the part. Titanium wire can be used over and over and it can carry a greater current load. Using steel or copper will be catastrophic.
Do it in a well ventilated area or you will end up with a buildup of nasty smelling explosive gas.

Mark T

 

[Herbiev]

Thanks Mark. Some great info there.

 

[idahoan]

Hi Mark, Great work on the Snow! I recently purchased a Silhouette Cameo machine for the same reason, gasket cutting, decals and stencils. The software that came with it Silhouette Studio V3 will easily import DXF files; this is one of the reasons that I purchased this machine. Are you using a different software package? Thanks for the tip on the gasket material; the stuff I have been using is difficult to get to cut all the way through.

Dave

 

[dnalot]

Hi

The software that came with it Silhouette Studio V3 will easily import DXF files

Thanks for the heads up.

To begin with I could not get the program to import the DXF file. As it turns out my drafting program needed to be updated and once that was done the problem went away.

I have the portrait model. It took a little experimenting to get the thing to cut through the material. The cool thing is if you don't take the sheet out between tries, it will retrace the same cuts with perfection. I finaly found that you have to set the blade depth on the cutter head AND adjust cutter depth in the software. Soon I will find out if it can cut a gasket with holes for number 0 screws. So far the smallest I have tried has been for number 2 screws.

 

[idahoan]

Hi Mark,

Glad to hear you got it sorted; the material I have been using is Interface Solutions TN-9004. It is very nice material; .017 thick and very flexible. It just doesn't want to cut that last little bit to break through. I had ran out and recently picked up some more so I can have another go at it.

Attached is a decal I made for my buddies Bremen walking beam hot air engine. The small letters are difficult to keep in place on the sheet while removing the parent stock but with some care it is doable. I used the Silhouette software to create the logo.

Dave