First cuts - cutting a taper

[topcat41468]

I have a craftsman 6" 101.07301 that i tore down cleaned up and rebuilt. I finally have it running. I also ground my first tool today (that you Mikey for your write-ups, it was much easier than I thought).

I was turning a 1/2" aluminum bar I have to see how it would go.

with a little adjustment to the lead angles, I got curly ribbons of AL, just like on many YT videos.

The surface was very rough, my guess is Im running too slow, have too much of a point and the lead screw is geared too fast. Bay hand I could get inconsistent surface finish. On the screw I got a 'fuzzy" surface. It polished up quite easily with some sandpaper.

I was turning in an independent 4 jaw chuck, that had centered out pretty well. Jaws 1-3 had 0.000 and jaws 2-4 i had 0.0015 difference.

I had the bar sticking out about 2" and cut from the end toward the headstock about 1" and took off .100 in 3 main passes. (through there were numerous skim cuts in the middle of that while I fussed with things).

So then I took my 1" micrometer and check the diameter. Near the headstock I was 0.400/0.4015 (slightly different on the horizontal vs the vertical). At the other end closer to the tailstock I was 0.405 - 0.4065 (same vertical vs horizontal variance).

0.005 over 1" seems like a lot, but it was not between centers.

I check the bed for level/twist with a machinists level. it was super close. At the tail stock end the backside was minutely higher than it was at the headstock. less than 5% of a bubble difference, just enough to say its a hair different.

1. can this just be deflection and I need to put things between centers?
2. I doubt it is twist.
3. how do I get the finish to clean up. ( attached a pic - I can take a better one, I was excited that it worked and sent a quick pic to my brother) I know this is a nebulous question that will get to how is the tool ground, speeds DOC ect. I found that as I turned the tool post clockwise and open the lead angle, it cut better and got cleaner, but not clean.

 

[benmychree]

Use some kerosene for a lubricant when cutting aluminum.

 

[mikey]

Hmm, that isn't hardware store aluminum, is it? If so, that stuff is so gummy that it's hard to get a good finish sometimes.

Can you show us some detailed shot of the tool? I can see that the honing may be an issue but am not sure because I can't see the edges well.

 

[markba633csi]

You're getting there! A bit more rounded-tipped tool will give a smoother finish. Also, try very slow hand feeding instead of power feed. Practice alternating hands on the carriage handwheel to give a steady, smooth carriage movement.
John is right about the kerosene- if you don't have any you can use liquid wrench or 3-in-1 oil in a pinch. You should be able to get a good finish dry if your tool has a good profile though and is sharp
-Mark
ps I had a cat named Topcat once

 

[Jim F]

I have a craftsman 6" 101.07301 that i tore down cleaned up and rebuilt. I finally have it running. I also ground my first tool today (that you Mikey for your write-ups, it was much easier than I thought).

I was turning a 1/2" aluminum bar I have to see how it would go.

with a little adjustment to the lead angles, I got curly ribbons of AL, just like on many YT videos.

The surface was very rough, my guess is Im running too slow, have too much of a point and the lead screw is geared too fast. Bay hand I could get inconsistent surface finish. On the screw I got a 'fuzzy" surface. It polished up quite easily with some sandpaper.

I was turning in an independent 4 jaw chuck, that had centered out pretty well. Jaws 1-3 had 0.000 and jaws 2-4 i had 0.0015 difference.

I had the bar sticking out about 2" and cut from the end toward the headstock about 1" and took off .100 in 3 main passes. (through there were numerous skim cuts in the middle of that while I fussed with things).

So then I took my 1" micrometer and check the diameter. Near the headstock I was 0.400/0.4015 (slightly different on the horizontal vs the vertical). At the other end closer to the tailstock I was 0.405 - 0.4065 (same vertical vs horizontal variance).

0.005 over 1" seems like a lot, but it was not between centers.

I check the bed for level/twist with a machinists level. it was super close. At the tail stock end the backside was minutely higher than it was at the headstock. less than 5% of a bubble difference, just enough to say its a hair different.

1. can this just be deflection and I need to put things between centers?
2. I doubt it is twist.
3. how do I get the finish to clean up. ( attached a pic - I can take a better one, I was excited that it worked and sent a quick pic to my brother) I know this is a nebulous question that will get to how is the tool ground, speeds DOC ect. I found that as I turned the tool post clockwise and open the lead angle, it cut better and got cleaner, but not clean.

View attachment 344619

What was your feed rate?

 

[topcat41468]

So all the questions helped me make progress.
It is hardware store AL. So that could be part of it

I’ll post tool pics in am. There are hollows on the tool faces but not the edges. It’s from the tous wheel. Sanding to 1000 grit with oil got the faces from the edge to 15-20% in to bright smooth finish and the edges are sharp enough that well... let’s say duh don’t run it along your finger.

I used wd40 as lube (no kerosene). That made a huge difference.
I sped up the lathe.
The feed rate was 0.048 in/rev and I reset the gears to 0.029.

I also drilled the ends and ran it between centers.

when I flipped it around and recentered in the 4 jaw i got it to 0.0005 all the way around. That felt good!

When cutting with this set up I had a bright surface while turning come up. When I shut it down there is still an edge to the feel when you rub in one direction but visually it’s a dull mostly smooth surface.

I think my tail stock needs adjusted. I was 0.008 small at the tail stock end vs the head over two inches. I know how to adjust It. So I’m am ill move it away from me. 1/4 of the offset I think. Half for diameter and half to split the difference from head to tail. (Is that right).

I was able to take 0.200 cut with out stalling it and got big longcurly chips. That felt good too.


thank you so far. The questions made me go adjust something’s and its Moving toward the right direction.

 

[mikey]

So all the questions helped me make progress.
It is hardware store AL. So that could be part of it

I’ll post tool pics in am. There are hollows on the tool faces but not the edges. It’s from the tous wheel. Sanding to 1000 grit with oil got the faces from the edge to 15-20% in to bright smooth finish and the edges are sharp enough that well... let’s say duh don’t run it along your finger.

Hardware store aluminum, whatever it is, is hard to turn clean. Run up your speed to the max your lathe will go and that will help.

I believe that the tool is sharp. I just want to see the tool so we can eliminate it as one of the causes. Aluminum is typically so easy to turn that having a finish like you're seeing is unusual and the tool is one of the primary suspects.

 

[Braeden P]

I have a craftsman 6" 101.07301 that i tore down cleaned up and rebuilt. I finally have it running. I also ground my first tool today (that you Mikey for your write-ups, it was much easier than I thought).

I was turning a 1/2" aluminum bar I have to see how it would go.

with a little adjustment to the lead angles, I got curly ribbons of AL, just like on many YT videos.

The surface was very rough, my guess is Im running too slow, have too much of a point and the lead screw is geared too fast. Bay hand I could get inconsistent surface finish. On the screw I got a 'fuzzy" surface. It polished up quite easily with some sandpaper.

I was turning in an independent 4 jaw chuck, that had centered out pretty well. Jaws 1-3 had 0.000 and jaws 2-4 i had 0.0015 difference.

I had the bar sticking out about 2" and cut from the end toward the headstock about 1" and took off .100 in 3 main passes. (through there were numerous skim cuts in the middle of that while I fussed with things).

So then I took my 1" micrometer and check the diameter. Near the headstock I was 0.400/0.4015 (slightly different on the horizontal vs the vertical). At the other end closer to the tailstock I was 0.405 - 0.4065 (same vertical vs horizontal variance).

0.005 over 1" seems like a lot, but it was not between centers.

I check the bed for level/twist with a machinists level. it was super close. At the tail stock end the backside was minutely higher than it was at the headstock. less than 5% of a bubble difference, just enough to say its a hair different.

1. can this just be deflection and I need to put things between centers?
2. I doubt it is twist.
3. how do I get the finish to clean up. ( attached a pic - I can take a better one, I was excited that it worked and sent a quick pic to my brother) I know this is a nebulous question that will get to how is the tool ground, speeds DOC ect. I found that as I turned the tool post clockwise and open the lead angle, it cut better and got cleaner, but not clean.

View attachment 344619

twist can cause taper and wear if you have that might be why it is a big difference.

 

[Mitch Alsup]

I used wd40 as lube (no kerosene). That made a huge difference.

WD-40 is 80%+ kerosene !

I sped up the lathe.
The feed rate was 0.048 in/rev and I reset the gears to 0.029.

I hog at 0.024" per turn and finish at 0.003"/t with a tool with a 0.004" radius tip.

 

[topcat41468]

I learn something new everyday. I didn’t realize that about wd40. I just knew it had the feel of kerosene so I figured good enough.

Some tool pics as asked for. Not perfect by any stretch, but I was not as intimidating as I felt before I just did it. Mikey’s write up helped a ton as did a couple other similar posts.

the vertical edges all slope in at 10 deg This was by plan and I measured them too (I know there’s a name for each angle I just have to use the drawing to keep them straight