Briggs & Stratton 6S - A Beginnig

[b.lindsey]

Another late lunch session got some of the relief done on the back side of the base. A 1/4" ball end mill was used to make the basic "L" cuts on either side and the remaining stock was removed with a regular end mill. The resulting fillet gives more or a cast look and better matches the prototype. The same method will be used for the remaining angles on the nose and the inside cavity as well. A couple of pictures of todays progress follow.

 

[b.lindsey]

Nearly done now with the base. Just some additional inside machining to finish off the wall thickness of the angled nose, some radius profiling on the back end and rounding the mounting pads on the bottom. Picture of where it is now follow. I hope to have this part finished tomorrow and then a little bead blasting on Monday at work and it should be replicate the original as closely as possible.

Bill

 

[rake60]

Bill I was wondering how that oil sump base could possibly be modeled.
Now I know! Beautiful work on this project.

Rick

 

[b.lindsey]

Thanks Rick. It seems that every part presents some unique challenges, even the gas tank and main engine (flywheel) shroud have several and varying radiused edges which all blend together so well in the original die stamped parts. Not sure how I am going to model them yet myself. It does give me a new respect for how and how well they did things back in the early 50's. Somebody had to make the dies even then and withoug the aid of of CNC, plastics or 3D modeling!! Then again, if it was easy it wouldn't be as much fun. Meanwhile...if you have any ideas for the main body casting, I'm all ears. scratch.gif

Bill

 

[NickG]

Bill, beautiful work again.

I liked the story about your introduction to the briggs and straton, I have similar memories of a suffolk punch lawnmower, again, at my granddads place. I was hooked on engines of all kinds since then! I got into stationary engines before model engineering, buying a few little things like a villiers mk 10 and a petter which I never got running. I've always liked the idea of modelling a lister D or similar, they have very clean lines which should make it not quite as tricky. I'm yet to do an I.C. engine but it's not far down my list of projects.

Nice photography and write up too.

Nick

 

[b.lindsey]

Nick,
Thanks for the comments. Haven't made much progress this week as work got in the way. This is my first foray in the IC arena and its probably a stretch in terms of ignition systems, rings, timing gears, etc. Fortunately there is good advice here and some local help too. Just last night i was visiting with a member of out local antiques engine club, who is also the designer of the model "Snow" engine mentioned elsewhere on the forum...what an inspiration. Anyway, I'll keep plugging away so please be patient.

Bill

 

[Deanofid]

Shoot. I missed the new batch of pictures a few days ago. Really nice work on that oil sump! A fine machining job.

Dean

 

[b.lindsey]

Its been a busy month since my last post on the B&S 6S. Finishing up the Fall semester at the university, including taking a Solidworks class myself unfortunately hasn't left much shop time for the little Briggs. But at last the base/oil pan is finished, and during the Christmas break I will be working on the piston, conrod, rings, and CI cylinder liner. A few pictures of the finished base are shown below and more of the next few parts will be forthcoming shortly.

 

[vlmarshall]

Great stuff. I like watching this little Briggs come together. ;D

 

[b.lindsey]

Thanks Vernon, just wish I had more to show lately.A lot of the last few weeks has been spent making a vessel for one of the faculty's research projects. It will be used for ultrasonic testing of things like jet fuel under high heat conditions across a .050" gap while pressurized with notrogen gas. I don't understand it all, but has to do with monitoring what goes on in a jet engine or rocket exhaust nozzle where internal sensors would be vaporized while ultrasonic sensors can work from the outside of the nozzle. I just make what they ask for...in this case solid 316 stainless, 4 in diameter. The center section is also 4" long with a 2" bore. Sorry to digress but thought it turned out well, especially for stainless. The pressurization valves and ports have yet to be determined. Heat will be provided by an external band heater fitting over the OD of the vessel with temps up to 400 degrees C.

 

[NickG]

Bill, thanks for showing your latest work - really impressive.

Nick

 

[Diy89]

Wow, that's nice for stainless.....

What a cylinder it would make for an engine....

 

[b.lindsey]

After a couple of false starts on the piston and some results I wasn.t happy with, I think the third time was the charm. Though not every aspect of the machining was photographed...like turning the final OD of .998"...most of the other steps are shown below. Photo 1 shows drilling the cross hole for the wrist pin once the blank had been faced on the bottom end. Photo 2 shows milling out the relief on the inside for the con rod. To get the pocket perpendicular to the wrist pin hole I had inserted a 1/4" rod through the cross hole and indicated off of that as the x-axis was traversed. That's the reason for using the rotary table shown in the pic, to rotate until the inserted rod was parallel to the x-axis. Photo 3 shows counterboring the bottom skirt of the piston.

After this was done the piston was reversed in the lathe chuck and the top end faced until the final length of the piston was achieved as show in picure 4.

 

[b.lindsey]

After the above operations, the piston (still in the lathe chuck) was transferred back to the rotary table on the mill and a slitting saw was used to cut the piston ring grooves as shown in Photos 1 and 2. A third wider groove was also cut which will be fitted with a perforated ring to allow oil to bleed through the piston to lube the cylinder wall as per the prototype.

Regards,
Bill

 

[b.lindsey]

The final few pictures show the mostly finished piston alongside the prototype piston and the wrist pins for each. I am thinking the wrist pin will be fixed to the wrist pin cross hole with set screws or 1/16" spring pins whereas the original used circular wire clips at both ends of the wrist pin. Final method yet to be decided.

Bill

 

[Deanofid]

It's always good to see a new post on this engine, Bill. The piston looks just dandy.

I've turned piston ring grooves in the lathe. Interesting method using the slitting saw and RT. It looks like a pretty good way to make very thin grooves.
Thanks for the pics.

Dean

 

[vlmarshall]

This is great! Another enjoyable update. ;D

 

[b.lindsey]

Short update today...got started on the cast iron cylinder liner. In photo 1 the ends had been faced to the final overall length and had started turning the OD from the 1.625" stock diameter to the 1.250" required, leaving a flange on what will be the top end of the liner. The second photo shows the liner reversed in the chuck to bring the flange diameter down to 1.375" and thinning it to a width of .125" Finally, with the flange again chucked in the lathe chuck the dial test indicator we used to make sure it was running true before drilling an initial bore of 1/4" in preparation for boring and honing to size. Not much but progress just the same.

 

[slick95]

Great up date Bill,

Looking forward to more progress. Super project

Jeff

 

[gbritnell]

Hi Bill, I applaud you fellows making somewhat bigger parts on small equipment like the Sherline. One of my first lathes was a Unimat. Although it stretched the capabilities of the small machine I did make some bigger pieces. It looks like you're making some steady progress on the engine. How is the cylinder going to attach to the crancase?
gbritnell