I’d like to blame the tool, but…

[Parlo]

That is a neat trick, I have a 6” scale and will try it out. Does 500rpm sound reasonable?

Set the tool with the spindle off.

 

[AlfromNH]

Set the tool with the spindle off.

Haha, yes indeed.

 

[pontiac428]

In addition to the point angle, how much back rake does that tool have? Aluminum likes lots of rake. Second, is your tool perfectly on center? Too high and it will rub, too low and it will gall.

 

[AlfromNH]

So, maybe I should post this in the goofs and blunders thread…

I bought a tool set from LMS, and I thought I was using the threading tool. But it’s not close to 60 degrees:

So I went back to the kit and found this:

I will try this one and report back.

 

[WobblyHand]

So, maybe I should post this in the goofs and blunders thread…

I bought a tool set from LMS, and I thought I was using the threading tool. But it’s not close to 60 degrees:
View attachment 440735
So I went back to the kit and found this:
View attachment 440736
I will try this one and report back.

It's all part of the learning process. Remember it, so you can help someone out in the future.

At least now, you might get better looking and useful threads. Make sure the bit is on center line, using the ruler trick.

 

[AlfromNH]

Make sure the bit is on center line, using the ruler trick.

yep, I like that scale trick you recommended:

 

[AlfromNH]

Better. The stick out is getting me now, there's a .007 difference in diameter at the outer end vs an inch in

 

[WobblyHand]

Better. The stick out is getting me now, there's a .007 difference in diameter at the outer end vs an inch in

Getting there. Yep, stick out really is a thing. For relatively thin stock, you're better off with only 3x the diameter sticking out. That and low depth cuts. This will reduce the deflection. Another thing to try are spring passes. That's when you repeat the cut at the same depth. It helps to get the cut more uniform.

If you have a tail stock that's centered on the spindle line you can use the tip to maintain the end position. You use a center drill which has a 60 degree angle on it to drill in the aluminum. Then the tail stock tip fits in the hole, supporting the stock. Even so you can get deflection between the support points. It takes a light touch and patience to do thin stock. If that's hard, you can learn how to use a follow rest. Personally, I find that they are hard to use, but they do have some utility.

 

[jwmelvin]

Your newest picture shows some double tracking. Like you engaged the half nut wrong once or twice. There is a smaller double peak of the crest.

 

[brino]

Here's what center drills look like:


...and a link to the Little Machine Shop page where I found that pic:
https://littlemachineshop.com/products/product_view.php?ProductID=1230&category=

it is the tapered shoulder that gives the 60 degree, not the initial little point on the end.

Here's what I meant by a long live center:


...and a link to the Shars page with that product:
https://www.shars.com/products/workholding/live-centers/2mt-long-nose-live-center-2

The idea is to keep the bulky bearing part of the live center far enough away that it does not hit the tool holder.
Of course, you still want the support as close to the work as possible to help limit play/flex.

For both there are many source with many price points.

Keep with it!
We all have to go thru the same learning curve.

Brian