Briggs & Stratton 6S - A Beginnig

[Deanofid]

It's gettin' there, Bill. Lots of setups in that one!

A few gallons of kerosene will take care that silly lawn.. "Gee honey, the grass just up and died!"

Happy spraying.

Dean

 

[zeeprogrammer]

Well the con-rod hooked me again.
I had to go through the entire thread and re-enjoy the pictures and excellent work.
The detail and photos are awesome.
Thanks.

Oh...a small apology...I ran across my own post and was aghast to see I'd called you by a different name. I've corrected that.

As for astro-turfing a yard...I've seen it done. But to be fair...I think the guy was tired of mowing a 45 degree slope.

 

[b.lindsey]

Thanks for the nice comments zee. I am still following your nice build as well. As for the yard, I have no excuse...its pretty flat, darn it! Now as for the name thing...I think I recall noticing that but figured it was just a slip so no apology needed. Heck, I'm just happy anyone is interested!!

 

[b.lindsey]

I think the only thing that got lost in the server transition were the pics below that I posted yesterday and a couple of responses to other's posts.

The first pic is of the con rod fitted temporarily to the piston and the second is a 3D model of the flywheel cover I hope to rapid prototype prior to machining the actual piece.

In response to arnold's post (which apparently is lost too), thanks for the encouragement.

In response to gbritnell's post (also lost), I like the idea of the teflon buttons for the wrist pin and will keep that in mind if plan 1 doesn't work out. I had found some 1/4" internal retaining rings at Lowe's the other week and hace a very small cutter to make the grooves for them so am hoping to try that approach first, mainly because it more closely duplicates the prototype which had spring wire retainers at both ends of the wrist pin. Will post progress on that as it is done.

I apologize if I am leaving anyone out here and thanks to all who are following the thread.

 

[4156df]

Having had one of these engines as a kid, I know what all the parts look like. I keep thinking there's no way you can fabricate this or that part and you always prove me wrong! Great work! Now I'm thinking there's no way you're going to build that shroud. Can't wait for you to show us how it's done.
Dennis

 

[b.lindsey]

Thanks Dennis....I have a lot of head scratching sessions too, or just sitting and staring at parts hoping for something to dawn on me which it usually doesn't :big: Such is the case with the shroud as well. I had thought about trying it out of sheet brass but to get all the proper radii, soldering it up wont work. Then I though about an english wheel perhaps..."gee honey...I need this little wheel thingy to make this part"...nah, that wouldn't get too far either. My present thinking is to just machine it from solid aluminum. The thickness won't be to scale but the exterior appearance should be close. Still can't help but think how nice a bright shiney brass shroud would look but without actually die stamping it i just don't see a way to do that.

 

[4156df]

Have you considered making a wood forming block and forming brass over that? It'd take a lot of annealing steps though.
Dennis

 

[b.lindsey]

I did think about that Dennis, but i can machine it from a chunk of aluminum about as fast as making the wood forming block. Keep in mind that the overall dimensions are only 5.188" top to bottom and 3.75" wide at the widest portion. Part of the reason for making a rapid prototype of it is to just look at it in 3D form rather than from the 2D drawing. And for now its just a one off also. I do appreciate the suggestion though as I certainly don't have all the answers by any means.

Bill

 

[b.lindsey]

I did manage to get the shroud on the RP machine and have added a few pics below for size comparison...one with the obligatory M&M (its even blue for you zee). It may take a lot of whittling but I still think its quite doable out of solid aluminum.

 

[arnoldb]

Hi Bill - thanks for mentioning the missing post.

Have you considered making the shroud from 2 separate brass plates - soldered together ? - Silver solder would be best...
Just a thought, as it looks like that should be doable as well - one "strip" with rounded corners and bent into a "U" shape, and the other plate for the top and back...

Whittling the ally would work as well

Kind regards, Arnold

 

[b.lindsey]

Arnold,
That was my first thought actually, my concern was that the corners would not be beefy enough to come back and radius them to scale. I even though of adding an quarter round piece of brass (on the inside) where the side and top joins which would allow additional material for radiusing the joint later on...but whittling from a solid still seems to me to be easier and preferrable in the long run.

Got to admit even the plastic RP model is a cute little bugger...when i get home tonight I want to see how it looks fitted over the flywheel, starter hub and screen.

Bill

 

[b.lindsey]

Just a quick shot of the temporary shroud shown with the flywheel and starter hub.Whether by design or luck the mesh screen on the starter hub fits perfectly in the shroud opening.

 

[rake60]

I don't know how you do it, but this thread just keeps getting better!

How you can replicate those parts has me amazed!

Please keep the updates coming.

Rick

 

[Deanofid]

That mock up looks so good, Bill. I will be very interesting to see how you cut up the metal part.
I'd be tempted to use the RP piece. It came out nice.

Does the prototype-er work like a router/plotter type machine, putting layers of material down to form the piece?

Dean

 

[kustomkb]

Some pretty slick parts your turning out Bill.

I've really been enjoying your progress.

Thanks.

 

[b.lindsey]

Thanks Rick, but in case you didn't notice the shroud is just a temporary replica. The actual part will be of aluminum and hopefully come out as well as the 3D printed part. Truth is the RP part would probably work just fine and a rather large headache would be out of the way, but then if someone wanted to build one, they would be out of luck unless they had a printer handy. This week I have been keeping both of our printers at the school running 24 hours a day with senior design projects. Truly amazing machines...they can make anything you can draw. As info, the shroud took just under 3 hours to run, not instant by any means but definitely quicker than it will take to make the permanent part.

Bill

 

[b.lindsey]

Thanks Kustom, progress is a relative term and I wish it were going faster, but now that the semester is nearly over, I should have a little more time to devote to the B&S.

Dean, you are correct....our machines slice a part into .010" layers and then lay down am extruded strand of plastic along the contour for that individual layer. In every case any outer and inner perimeters are laid down first and then filled in between to complete the layer, all computer controlled. Multiple parts can be made at once but each layer has to be completed for every part before subsequent layers can begin.

Another reson for not using the RP part is that I'm not sure it can stand the heat and/or vibration over extended periods of time.

Bill

 

[mu38&Bg#]

The durability of an RP part depends on the method and material used to produce it. Years ago they were making intake manifolds for engines in SLA machines and running them under the hoods of cars. 10 years ago I had a 2" diameter fan rotor made by the FDM process as described above in ABS and I've run it at over 60,000 RPM. Today they are using lasers to sinter powdered metal into parts virtually as good as cast or machined.

Fun stuff, but costly. I would expect a quote for a part like that shroud to be 200-300USD using FDM.

 

[b.lindsey]

Dieselpilot,
As you noted, this was done by the FDM method in ABS. With 3.5 cu.in. of material used, the direct cost would be around $20-25 but of course that doesn't include overhead for the machine, maintenance, etc. Even if it could be done commercially for $100, that's a bit pricey and would turn folks away I am sure. That is the main reason I want to replicate it by more conventional means.

Bill

 

[mu38&Bg#]

Absolutely. If it were me, I'd make it in fiberglass and epoxy.