greetings two stroke fans. what we're going to do today is I'm going to give
you a demo of how to plot a cone out onto a flat piece of paper that can then
be transcribed onto a piece of sheet metal what I'm going to do is I'm going
to make the measurements fit this what I can do is once I've done the cone then I
can use these to check the dimensions okay so I can show you that they
actually match what they're supposed to be so now we will magically jump to the
software and will enter the figures of 64 mil base 20 mil tip 100 mil Center
length and for the purpose we're going to put a sheet material sheet in of zero
but normally you would put in the thickness of the actual sheet metal that
you were using you can do this scribe this directly on to sheet metal
but I would actually do it onto paper because you might find you want to make
another expansion chamber and then you can just take the pieces of paper out
and scribe them on to sheet metal again okay here we are at our plot window will put
the diameter of the base section in which we had at 64 millimeters 20
millimeter ID for our tip section Center length is 100 millimeters and
because we're just going to make a paper one we actually just put 0 in for the
sheet thickness on top so we hit plot cone
there's our numbers that we're going to use so here we are back again I've got a
piece of paper stuck down I've now got the dimensions that I want for the cone
first thing we want to do is go across here and just put a datum point which
will be the center of where we're going to take our compass point our first
measurement will be the D measurement the runs outwards so D radius
is the first radius for the base section the C radius is the smaller one so
I'll start out with a larger one now it's a hundred and forty eight point
nine three for this one from here line second one our C
dimension is forty six point five four if you want to do it in imperial with
your vernier and measure the compass and whatever there's a little metric
converter in the in the software in the input calculator values window forty six
point five four so we'll go down to forty six forty six point five okay put
it in our point there inside one go all the way around you know next point take
your pen pencil whichever put it on the datum point there and draw a line across
there pretty easy so far now the next one is our A dimension
which will be the chordal width across one hundred and eighty six point one
four place that there that one there mark our spot
take a ruler from there back to a point down here a little datum point down
here where we had that okay yep and draw a line from the and
there we go the B dimension is not actually required but I put the B
dimension in there so you can just cross check the figures just to make sure it's
right fifty eight point one seven so we'll just go to 58 point there about
58 point one and we'll just measure that to there to there okay so a distance
across the the B measurement correlates with what we should have here's the B
one okay because it's just more accurate to use the A one across here alright the
B one is just provided so that you can just cross check the figures if you
measure the B one and that's not right then you'll probably want to double
check all the figures that you've used before you cut everything out
there we go now I'll talk a little bit about actually rolling the cones and a
later video we'll get into that there is some a few methods to do that but I'll
be honest with you look if you know a sheet metal place where you buy the
sheet metal and he's got a set of small set of rollers and he can roll the cones
for you in the rollers first and lead you to do the rest of the welding then
get it done because you know actually rolling the metal can be a bit of a pain
to do you've got to keep putting it through the rolls and through the
rollers and there's other ways that we can beat that around but you won't get
as nice a job and just remember that when you're making an expansion chamber
you know to tuned pipe neat is the name of the game we've got
to keep it neat that's why as I said no weld beads inside the pipe or anything
like that and you'll see when you're actually rolling the sheep and you go to
weld it together by the time you finish welding by the time you finished rolling
that sheet okay you'll find that you can't roll sheet metal without
distorting it to some degree and those little distortions will leave you with
an edge that's not quite perfect around the top and not quite perfectly flat
around the bottom once you've actually rolled it all out through the rollers
and that's why as I said before always go to the outside of the line a bit a
little bit of extra metal so that when you make your cone you can stick down
some paper and you can rub the cones on each in you know if you've got a linisher
you can use that and bring your sizes down to size okay now let's just do some
checking on our cone all right and there we go twenty millimeter push that down
to our top there
check now Center length which was 100
there you go since a length which is 100 and their base diameter which was 64
okay as you can see sorry now if you if you need a cone to be an
angle at the top like that okay what you would normally do is you would pie slice
the cone and then slice around here and then tilt the cone and put the other
piece in but what you can do is you can actually use the calculator and I will
give you a link to the calculator which Nico from Hollaendaren our own channel sent
me if you don't know Nico's channel I'll put a link there go to his channel
he's nearly got a thousand subscribers so he needs more subscribers that's for
sure but he does two-stroke stuff he's doing a scratch built 4 cylinder
two-stroke engine at the moment that's pretty radical and so you might enjoy
watching that as well so nico sent me a link to some software
it's payware unfortunately but is what it is and with that you can put the cone
sizes into it and it will actually print out ones that have an angle included in
the top in the plot so when you cut it out of the paper it's already got the
angle in there and when you put it onto the metal so then you might want an
angle one so if you've got a two-stroke motor cross pipe where you've got a
diffuser cone coming up and a neutral chamber here and then you want to have a
right angle inside part of the diffuser so you can take sections but if you've
got any more questions on that put it in the comment section as always I always
answer questions if you liked the video hit the like button if you haven't
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because YT doesn't and that would be much appreciated if anyone
needs the software if you think anyone wants the software please share it's
freeware I don't charge anything make anything out of it so that will do it
for today until next time bye for now