question on webster drawings - what is this

[werowance]

looking over the Webster plans, trying to figure out if I want to attempt to build one or not, on the very first sheet I come up with something I am not understanding. can someone tell me what this hole is and help me read the plans properly?

 

[el gringo]

looking over the Webster plans, trying to figure out if I want to attempt to build one or not, on the very first sheet I come up with something I am not understanding. can someone tell me what this hole is and help me read the plans properly?
View attachment 102692

 

[el gringo]

That tapped hole is for the exhaust valve arm return spring. The fhs is a Flat Head Screw which I never use.
I am taking pics as I go along . If you think it might help you I can send some to you...
RAY M

 

[Brian Rupnow]

Werowance--Here is a link to my build. This was my first i.c. engine.---Brian
https://www.homemodelenginemachinist.com/threads/anybody-want-to-guess.7687/

 

[werowance]

i have another question on the Webster drawings, on the fly wheel I don't see where the set screws or pins go nor do I see what size etc. but was wondering, just as the flame eater engine where I put 3 set screws around the outer edge and drilled straight down to the crank shaft, wouldn't that work? made life really easy getting at the screws.

Bryan

 

[Brian Rupnow]

The best arrangement of set screws in a flywheel are two at 90 degrees apart. If you have a keyway, then one set screw should set directly above the keyway. Putting three set screws at 120 degrees apart is not a good idea, and may actually make the flywheel wobble.---Brian

 

[kquiggle]

Bryan - I started a Webster build way back in 2014, when I was just learning about machining. Had to put in on the back burner for awhile due to "life happens" stuff (moving and relocating my shop, among other things). In any case, I also put together a build page (link below) which includes a list of references to numerous other Webster builds.

I think the Webster is a good project as it involves a number of different machining/building techniques - it's challenging for a beginner but not so difficult as to be impossible for someone on the learning curve. One of the reasons it's taking me so long to complete my build is that I wanted to use the build to improve my machining skills in various techniques, so I've been trying out different methods for some of the parts - I've generated some scrap but I've learned in the process.

Maybe I'll finish up this year ;-)

https://sites.google.com/site/lagadoacademy/machining---lathes-mills-etc/build---webster-engine

 

[werowance]

another question, was sourcing some materials for it and it calls for .313 aluminum for the bearing stands.
now I can actually find .313 6061 plate and its pricey, but I can also find what is advertised as 5/15 6061 for much much cheaper so this brings the question, is 5/16 which would be .3125 really just .313 plate that is advertised or rounded to the nearest fraction, or is there really a .0005 difference between the 2 in reality? I guess I'm just wondering is the advertised size 5/16 is nothing more than .313 or vice versa? and honestly would .0005 really make a difference anyway?

and yes I realize I could mill down some thicker plate to the proper thickness but hey, since I'm having to buy some stock anyway, might as well get what I really need to save time and chips.

 

[Brian Rupnow]

That 0.313" dimension is just a rounding off of 0.3125". You won't find 5/16" aluminum plate but you can buy 5/16" aluminum flatbar.

 

[kquiggle]

werowance - I think there are a lot of reasonable substitutions that could be made in the plans, so long as you adjust mating parts accordingly. There are obvious critical dimensions like crank length and gear ratios, but I certainly the tolerances aren't anywhere near 0.0005". I try to get as close to the specified dimensions as reasonably possible, just as a way to hone my machining skills, but I would guess that as far as the Webster is concerned a few thousandths difference here and there won't matter.