Blueprint help

[purpleknif]

I was looking at plans and printed the set for the Comber Rotary Engine.Looks good except... I see a number of dimensions with an S inside a circle or a B or C. The S is used for G D & T to mean "regardless of feature siz" but I don't think that's what he's after here. What am I missing ?


Thanks

 

[weez]

Here are the meanings of the circled letters that Elmer uses.


I also made a Comber. The build log can be found here. Good luck with your build. I look forward to seeing it.

 

[GailInNM]

Elmer has his own set of notations for drawings.
Here is a link to them.
http://www.john-tom.com/ElmersEngines/ShopWisdomRevNov07.pdf

Gail in NM

 

[purpleknif]

Thanks ! Haven't seen these before .

Probably gonna cheat and use my CNC jig mill at work for the cam .

 

[GailInNM]

Purpleknif,
If you are going to CNC the cam, I have a printout in one degree increments of the coordinates for using a 1/4 inch diameter cutter.
Or, if your CNC control can handle parametric equations I have them also.
I will send either or both to you if you want them.

For reference, if you want to look up some of the history on this engine on the internet, search for COOMBER engine. Note the two "O"s in the name. When the original article was published, the name was misspelled and and it was never corrected.

Fun engine. You will enjoy it.
For your entertainment, here is the youtube link to the first one I built.
https://youtu.be/f_KaGygrND0

Gail in NM

 

[purpleknif]

Haven't tried it yet on the jig mill but the manual shows a "cam function" . Use polar coordinates, starting rad and ending rad. Should work. When I get a chance I'll program it and run the graphics. Gotta do it before I retire so I can use the machine.