/diy/ - Do It Yourself

Yes, you read that right.
Never mind stupid questions. I've asked plenty, and gotten good advice (and plenty of REALLY shitty advice) here.
But tonight, instead, I've got a really stupid answer to share.
I'm using a lathe to turn down a 9" octagon of 4/4" purple heart into a roughly 1" thick circle.
It's the first stage of a larger project intended as Christmas gifts for my grandkids.
Well, I just can't get this shit to true up.
I've got a 9" wide, 1" thick piece of wood in the lathe between the spur center in the headstock and a live center in the tailstock.
I can pretty quickly make the piece fairly round with a bowl gouge.
And yet,,,
It's not quite circular.
When I gently place a skew chisel against the piece, it chatters as though the piece is oval, NOT round,
OK, I don't have a clue WHY it isn't quite round, but easy fix, all I have to do is true it up, right?
Nope.
Jesus titty-fucking Christ NO!
For some reason (I assume relates to the harmonics of the rotation speed related to the frequency of the inevitably bouncing skew chisel), I just CAN'T true up the piece.
The stupid answer?
SPEED UP THE LATHE.
After moving the belt to a faster position, truing up the piece become a graspable reality.
Oh sure, the piece still isn't perfect, BUT IT WORKS.
If you have some scientific explanation, that's great, but please keep it too yourself.
The point is: sometimes good looks, clean living and being lucky enough to be smarter than most just isn't enough.
You need some stupid, yet mystical answer.
In this case it was "go faster".

Nuf said.
Please share your "stupid answers".

Halp! On my lathe, I can't make a tennon for a bowl chuck to save my life.
I've watched every youtube video there is, I've tried time and again, but it just can't hold my workpiece.
Any tips besides the obvious?

>>1325939
>What do you sleep on?
The couch and a BAC of at least 0.1%.
protip: never become somone's FOURTH fucking spouse.

>>1290836
Thanks, but I've decided to use the chop saw.
I got it as close as I could to 45 deg with a square, and cut my pieces.
I'm making 5 boxes, so I started with a throw-away prototype to learn with as I went.
And while each cut is really close, when I put the whole thing together, the cumulative error causes at least one corner to be a little off.
I'm heading over to youtube to see if I can find out how to dial-in the chop saw for greater accuracy.
Hopefully, I can shave less than a blade width off so the boxes don't get much smaller.

>>1088141
>and after a few days (or weeks or whatever), start from scratch
I've been doing that for about a month now.

>>1088142
>Ryobi table saws are shitty
Yes, they are.
There's a slight wobble to shaft even with no blade on.
But it's not like it's just wobbly or something.
I think I'm having a stroke.
I just went on to a different project involving my cheap-ass harbor freight router table.
I'm using a slot-cutter, and needed to move the bit, router etc down 1/16".
So I lowered the nut on the height guide one full turn.
It's a 3/8" 16 tpi bolt.
Nope.
One turn of the 16tpi bolt only moved the bit 1/32".
I think I may really be having a stroke.