Briggs & Stratton 6S - A Beginnig

[gbritnell]

Hi Bill,
Seeing the two pieces together brings a question to mind. Are you going to make the fins tapered as on the full sized engine? If so you could probably rough them out and then go back in with a small tapered end mill to finish them up.
George

 

[b.lindsey]

Good observation George and a good question too. The answer is probably a little bit of a cop out... but the plan is to use a 1/8" face width slotting saw and doing all of the fin work on the rotary table with everything referenced from the center of the cylinder, and leaving approx. .100" of aluminum around the cast iron liner on all sides (more properly the three finned sides) at the full depth of the fins. At half scale, I think the visible difference will be minor, plus the fact that the shroud covers one side of the fins, and what I am calling the cylinder shield (the wrap around part where the name plate attaches) will cover the front and pulley side of the fins for all practical purposes. In this case its more a matter of how I think I can most accurately machine the fins, and clamping the crankcase vertically on the rotary table is well within my comfort level, though even then it will be done slowly. Lastly I have to say that my skills are not up to yours as the work you have done on your tranny case is stunning to say the least :bow:

The attached .pdf shows the relative fin thickness vs. 1/8 spacing between fins. What I may do for appearance sake is to round the outer edges of the fins once they are cut to better match the appearance of the original. I am certainly open to other suggestions though.

Bill

View attachment BS6S Crankcase1 (1).pdf

 

[b.lindsey]

Even though the label package was labeled for inkjet printers (all I could find), I printed it on the color laser and it seemed to work fine. The whole page (six sers of labels) is shown in photo 1. Photos 2,3 and 4 show them applied where they would be on the prototype. A little more care in trimming and applying the one to the top of the air cleaner would have resulted in a better application but thats why I have 6 sets to play with . Overall the opacity is good, and there wasn't any smearing as might be the case with ink jet printing especially if wet. I'll play with them a couple of days to make sure they stick well and such, but now that the template is done, even if they needed replacing periodically its no big deal. All in all this was a good trial and the clarity of the lettering came out very well. Thanks for checking in.

 

[b.lindsey]

Here's one last picture of the shroud and air cleaner together.

 

[steamer]

That is really looking great Bill. Keep it up !

:bow:

 

[b.lindsey]

Thanks steamer. I was really pleased with how the "decals" came out. Its a technique I will definitely be using again assuming they hold up well. The only downside is that you can't just make one small decal...actually I could have put a lot more on that one sheet.

Bill

 

[ddmckee54]

If you haven't sealed the decals yet the first time you get oil or just about any other liquid on them you'll probably end up with a mess. The usual sealing method would be to shoot them with several very light coats of clear lacquer with plenty of drying time between coats. Then apply a medium wet coat to even out the finish of the decal. Apply your decals, shoot a clear coat over everything and as long as you're careful with your engine the finish should outlast us.

Don

 

[b.lindsey]

Thanks Don, I do plan on trying (within reason) to use and abuse them to see what will happen....water, oil, greasy fingers, etc. Fortunately none of them will be in areas that are subject to much of that but i still want to know. If it makes a mess as you suspect then your suggestions may be helpful in prolonging their life. The base materail of the film in polyester acording to 3M.

Bill

 

[Deanofid]

Those look really good, Bill. Very real.

 

[b.lindsey]

One of the small tasks that had gone undone was adding the locating dowel pins to the base/oil pan to locate it relative to the bottom of the crankcase at assembly as was done on the prototype. First I continued the shallow holes that had been put in earlier all the way through the base and reamed them for a 1/8" dowel pin. ( photo 1) Then the base and crankcase were fastened together, inverted, so the hole locations could be transferred into the bottom of the crankcase as shown in photo 2 (sorry it isn't clearer). Photo 3 shows the holes in the bottom of the crankcase. With this done the dowel pins were loctite'd into the base flush with the bottom (photo 4).

 

[b.lindsey]

Finally the last photo shows the base and crankcase fitting together with the help of the locating pins. All that's needed is the gasket between them. Another minor, but necessary task out of the way now.

 

[b.lindsey]

Things have been hopping at work...not so much model work as the senior design students working on their projects. Unlike prior years, some of these guys actually show up at 7 AM to get started reather than at noon or 3 PM and then expecting me to hang here with them until 9 or 10 at night. That ain't happening!! (Note to self: Buy some Red Bull stock! I think these kids are living off the stuff!!) Anyway the B&S project, mainly the crankcase at this point has been relegated to 15-30 minutes here and there as one of the knee mills is open...but better some progress than none. Also some work has been done on the governor. The 4 pictures below show that bit of progress so far. Now I need to solder some brass tube to the bottom of the bracket and along the bottom of the vane to act as a hinge. Not sure how functional it will actually be, but it will look the part at least.

The bracket is made from .009" brass stock. As was done on a few other parts, a paper template was glued to the brass and the central bend made by pressing it between two pieces of angle (photo 1). Once bent, the other contours were cut out with scissors, and filed or Dremel'ed to the template lines until it looked like photo 2. There is a little bit of a "U" shape on the small tab at the bottom to give it a little more strength...i hope!! The bracket will fit at the top of the plate (screw holes yet to be done) and shown in photo 3. Finally the vane was cut out the same way but out of .016 brass. and sanded to the template lines on the small belt sander.

 

[b.lindsey]

The next three pictures show some of the progress on the crankcase, mainly carving out the inside enough to get the crankshaft in. Its going to need a little more relief for the crankshaft to spin freely in the crankcase but as soon as that gets done I can press the bushing in the back side and hope like crazy everything lines up well so the crankshaft spins freely.

The good news is that Spring Break is next week so I should get some early morning time or lunchtime in on the mill.

As always, thanks for taking a look.

 

[Deanofid]

Still watching, Bill, and enjoying all of it.

Dean

 

[b.lindsey]

Hi Dean,
I know there hasn't been much to watch lately, but the support is still very much appreciated. More soon I promise.

Bill

 

[ozzie46]

I don't say much but when ever this thread comes up i"m alookin and absorbin .

Ron

 

[b.lindsey]

Thanks Ron, your lookin' and interest, even if quiet is appreciated also!

Bill

 

[b.lindsey]

I managed to get a good hour or so of shop time yesterday afternoon and made further progress on getting the inside of the crankcase milled out at least enough for the crankshaft to fit and rotate inside it. Its still far from done but compared to the previoius post a good amount of chips were removed. Today will be the test to see how well things line up after the other bushing is pressed into place. Hope to have an update on that later.

 

[b.lindsey]

The trial fitting of the crankshaft into the crankcase with both sleeve bearings went as well or better than expected. There was some slight binding but some oil and attaching an old Sherline 3 jaw chuck to the pulley side of the crankshaft allowed the shaft to be turned with minimal effort by hand. After a few minutes it had already become easier to turn and I think a little more running in by hand will correct this even more. I want it to spin freely but still want what feels like a good running fit. The attachment of the piston and con rod (photo 1) didn't add any addition binding at all other than the friction of the rings in the cylinder. I do need to finish carving out the inner walls of the crankcakse though as the con rod cap hits against one of the ends. I wanted to see how things were looking though before removing too much metal that can't be added back! Photo 2 is just one of those "see how it's gonna look" shots that keep me motivated. The last photo is just from the top of the cylinder looking down at the piston. So far, so good....will get back to the crankcase on Monday. Over the rest of the weekend I am going to try and finish up the governor.

 

[ozzie46]

Looks real good Bill. What are you using to hog out the inside of the crank case? It looks pretty deep. Do they make end mills that long?

Ron