Fairbanks 80HP 3 Cylinder Model

[cfellows]

I can't seem to get excited about resuming work on my Bessemer model, so I've decided to tackle another engine model that has been on my list of projects to do for some time now. This is the Fairbanks 80hp, 3 cylinder.

Castings have been available for an IC version and I've seen several of these at model engine shows. Here is a video of one such model...

[ame]http://www.youtube.com/watch?v=Gqsi6Z2qsEI[/ame]

My engine will be somewhat smaller with a 3/4" x 7/8" bore and stroke. And, although my engine will be four stroke in operation, it will be powered by compressed air using over head intake valves and my slave exhaust valve. For those of you familiar with the IC model, and perhaps the original engine, my version will have the main bearings and caps contained in the upper crankcase half instead of the bottom. While I want to adhere to the original scale dimensions as closely as I can, my model will be somewhat stylized and probably not have all the detail seen in the original. However, I will try to add some bling and make it somewhat interesting.

Finally, I'm making a serious attempt to model each part in Alibre before constructing that part, so I should end the project with a complete set of drawings. Below is the first installment showing the upper crankcase half. It will be machined from solid aluminum or cast iron, yet to be decided. If you download the 3D PDF, you can click to activate it, then rotate the part by holding down the mouse and dragging it around.

https://dl.dropboxusercontent.com/u/29733857/Crancase%20Top.pdf

Chuck

 

[jgedde]

Is the original a Diesel? The local antique power association has a 5 cylinder Diesel that looks very similar. I can sit and watch that thing run all day! It's mesmerizing! Each time it fires, each cylinder shoots a smoke ring.

John

 

[cfellows]

Is the original a Diesel? The local antique power association has a 5 cylinder Diesel that looks very similar. I can sit and watch that thing run all day! It's mesmerizing! Each time it fires, each cylinder shoots a smoke ring.

John

I don't believe the original engine was a diesel... I think it uses low tension igniters. I could be wrong.

Chuck

 

[jixxerbill]

Wow chuck, looks like you are in for an adventure.. I wish you the best of luck and keep the pictures comming please. I'll be looking forward to every post...Bill

 

[kuhncw]

Chuck, you've come up with another interesting project. Nice job on the solid model, by the way.

Regards,

Chuck Kuhn

 

[skylark]

I have just completed a 3 cyl. 4 stoke, O-head cam engine of my own design, but I am experiencing quite a lot of viberations, - its reving at some 9200 r p m. on a 16 x 8 master prop , ( 10 cc per cyl.) - 30 cc. My fireing order is 1 - 3 - 2. I am just wandering what is the fireing order on your engine. ?

 

[Till]

I don't believe the original engine was a diesel... I think it uses low tension igniters. I could be wrong.
Chuck

This is the Engine pictured in the first post:
[ame]http://www.youtube.com/watch?v=nnRiq8nTkic[/ame]

 

[cfellows]

Thanks, guys. Didn't have the right materials on hand to start on the engine this weekend so SWMBO "pursuaded" me to build a doll bed for the granddaughter. Now everything in the shop is covered with sawdust...

Went down to the local metal supply store today and picked up a nice chunk of Aluminum.

Measured it up and mounted it in the bandsaw to carve off a piece.

Finally cleaned up the two edges with a 2" face mill. So now I have chunk of aluminum that's oversized by about 1/8" on top and sides and almost an inch too long.

This is going to require a lot of hogging with an end mill and my experience with this sort of thing has always been mediocre at best. Guess the secret is to take it slow. If anybody has any hints or videos worth watching on doing this without a CNC mill, I'd love to see them...

Chuck

 

[johnmcc69]

Glad to see another one of your builds start Chuck, great job on the crankcase model. You're going to have lots of fun with Alibre.

John

 

[cfellows]

Thanks, John.

Here's round 1 of the hogging process...

I first positioned the spindle over the middle of the cutout area. Then I set the spindle depth stop to bottom out 1/8" above my final depth. With a 1/2" roughing mill in the spindle, I used the drill press handle to apply steady downward pressure as I cranked the table back and forth a counted number of turns each way to establish the slot. The resulting slots are undersize in depth, length and width. I am planning to sneak up on the final dimensions by working from the inside out.

Chuck

 

[cfellows]

One last picture for tonight. I've got about 5 hours total into this so far.

I continued on with the 1/2" roughing bit...

I have the hollowed out parts to within about .015" of each line and .005" of the depth. I'm very happy with the results. I found that by going full depth in the initial slots, it was much easier to control the widening process. The roughing bit cut pretty effortlessly at full depth and there was no tendency to dig in or pull the table against the leadscrew backlash.

I'm going to leave the openings slightly undersized until I finish the crankshaft. Then I'll remove the final few thousandths as needed to fit the crankshaft to the crankcase.

Chuck

 

[cfellows]

I got started on the next piece that I don't expect to be easy. I'm calling this my first attempt fully expecting to make 2 or 3 before I get it right... who knows, maybe I'll get lucky! This will be a built-up crankshaft. I'm starting with a piece of hot rolled steel, 3" long x 1" wide x 1/2" thick. The maze of layout marks looks a bit confusing.

Next I drilled 7/32" holes in what will be the opening between the webs.

This was followed by sawing out the waste and mounting it between centers in my lathe. Forgot to mention that I had drilled countersunk holes on each end.

Here it is after I have turned down the connecting rod journals to 1/4".

And finally, the three crankshaft throws have been separated.

Next I need to clean up and size the thickness of the sawn ends. Then I'll drill 5/16" holes through the other end of the webs for the crankshaft journals which will be made from 5/16" drill rod. These will be loctited and perhaps pinned to secure them
.
Chuck

 

[cfellows]

Picking up from where I left off yesterday, I decided to bore the mains journals in the lathe. While positioning of the holes exactly isn't particularly important, getting them parallel to the connecting rod journals is critical. So, I mounted them in the 4 jaw chuck and used a DTI to center and position them as close as I could get, probably within .005" or better.

After center drilling, I drilled a 3/16" hole through both webs, then enlarged the hole with a 1/4" carbide end mill. Figured this would straighten out an wandering by the 3/16" bit.

Next I enlarged the holes with a letter N bit followed by a 5/16" reamer. I also turned some clearance on the outside of the webs, leaving a small circular piece on each side to contact the crankcase. Here's the three pieces slid loosely on a length of 5/16" drill rod.

I mounted the crankcase in the milling vise and indicated it to the centerline for the crankshaft. I'm using a 5/16" ball end mill to cut the crankshaft main journals into the crankcase top.

Here's the upper crankcase with the crankshaft mains milled in.

And here we have the crankshaft parts sitting in the crankcase...

Next I have to figure out how to hold the webs at the proper angle while the loctite hardens. One of the possibilities I've considered is using set screws through the bottom of the webs against flats in the crankshaft main. Not sure I would even need loctite if I did that. Anybody have any thoughts?

Chuck

 

[cfellows]

Gonna put the crank on the back burner for now. I drilled the holes for the cylinder barrels and will likely do the cylinders and heads next. Kind of trying to keep my options open as long as I can.

Chuck

 

[cfellows]

The 1 5/16" 12L14 steel round I ordered for the cylinders and heads hasn't arrived yet, so, today I started on the lower crankcase. I began with a chunk of aluminum 5 1/8" x 3" x 1 1/4" thick. The first step was to hog out the inside. This picture shows the part after the initial hogging. Like the upper crankcase, I used a 1/2" high speed steel roughing end mill. I set the depth stop on the quill to 1" then I applied moderate downward pressure on the quill with one hand while cranking the table in the Y direction back and forth 13 turns each way. I had to pause and vacuum out chips 3 or 4 times for each full depth pass. I completed this part of the hogging operation in about 40 minutes.

With the roughing end mill locked at full depth, I began traversing the perimeter of the opening taking about .030" at a time. It took about another 10 - 15 minutes to work my way out to the lines. I'm really happy with this method of hogging. It's fast, very low stress, and the results speak for themselves. The only downside is the rough finish left by the roughing mill, but these things are usually on the inside of the engine where no one will see them.

Here is a picture of the upper and lower crankcase together. I still have to mill the indents on the sides of both top and bottom, but that will likely be about the last operation. I also have to do some shaping on the ends of both the top and bottom. Current plan is to have a 5/16" long piece extending from the ends of both crankcase halves that will form a 1 1/4" diameter boss surrounding the crankshaft.

Chuck

 

[cfellows]

Here is a drawing of what I'm shooting for on this engine. The drawing is subject to change, but represents my current vision.

Chuck

 

[cfellows]

I started on the flywheels today. I had a length of 4 1/2" diameter steel pipe that I'm cutting the flywheel rims from.

Here's the rims cut off and trued up except for the ID.

Thought I'd include a picture with the rims kind of where the flywheels will be. I kind of like to get a feel for how these things are going to look.

I'll be making the flywheel centers from aluminum and pressing them into the steel rims. These will be eight-spoked flywheels and I'm planning to make a video of at least part of the process.

Chuck

PS... The 12L14 for the cylinders and heads came in today. :cartwheel:

 

[aonemarine]

Lookin good Chuck.

 

[cfellows]

We had to babysit the grand kids the past couple of days so I haven't had a lot of shop time.

I dived into Alibre again this morning and made a preliminary attempt at a flywheel. Doesn't look too bad, but the dimensions will need tweaking a bit. This 3D drawing, particularly when you get into assemblies causes me major brain cramps! Unfortunately, for me, it's too easy to fall back to Visio and 2D drawing. I probably need to force myself to use Alibre as my only design tool. That's the only way I'll ever get half way proficient.

Chuck

View attachment Flywheel.pdf

 

[johnmcc69]

Looks great Chuck, you get this Alibre figured out, you'll be unstoppable.
Great work.

Doesn't matter what you draw 'em in Chuck, it's all about the finished product.

John