New to me SB 10L screaming at me while parting

I thought a good introductory job for the South bend would be trying the parting tool on a piece of black steel pipe.

Everything seems to be running smooth and within spec.

When I try to use the parting tool the lathe screams at me.

I have a very untrained ear for machine tools.

I'm still very new to machining and this is my first lathe so any advice is appreciated.

https://youtu.be/ZRpGkouxRcI

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Nice lathe! Some things I noticed.

I don't hear your back gears so you are probably going too fast. Try around 80-125 RPM to start.
Once you are slow enough you can be more confident to use the cross feed to let the machine do the work. It is preferred and smoother. I usually use 64 threads per inch setting or maybe more if the material is hard.
You'll want to use some cutting fluid.

Some things I couldn't tell
Is the material suitable for this operation? Try the operation with some free machining steel like 12L14, 8620 or some easy aluminum like 2011, etc.
What does your cutter look like? Is it sharp? I usually touch mine up with a stone before use.
Is your cutter on center? That is critical with parting.

Good luck, parting seems like it would be easy right? lol Truth be told a hack saw and clean up cut using lathe is way faster! Still I usually part a portion of the way through the material and then use a power hack saw and clean up after on machine...

Thanks Kevin T!

I obviously have a lot to learn. I ordered "how to run a lathe". Being handy but inexperienced, I have a feel for what to do but I have no concept for speeds and feed rates yet. I basically know enough to get myself in trouble but not to know why I'm in trouble.

I had centered the parting tool on the middle of the tail stock. I just made the AXA tee-nut on my Bridgeport and mounted it so everything there is tight including a brand new HSS parting tool.

I slowed everything down using the back gear and followed your 64 thread per inch suggestion. Also added some lube. A little slipping of the saddle clutch but it went right through with no noise and made a nice part.

Something on my to-do list is to look around Craigslist and Facebook and try to find a bunch of scrap steel to start making some projects with. Unfortunately I'm very limited in my metal selection at the moment.

QUOTE " Also added some lube"
Yes, cutting oil is going to help a lot to get rid of the chatter.,

Re-grind the parting blade to ensure it is sharp, slow down the spindle speed and check for anything which could be reducing the rigidity of your tool. Make sure your carriage is locked down and gibs are properly adjusted. Minimize blade stick-out as much as you can. Parting blades are notoriously fussy on small lathes because they require a tremendous amount of rigidity to cut properly. Even a tiny little bit of swarf trapped behind the parting blade in the tool holder is often enough to make them chatter. A consistent feed is also needed. Too fast or too slow and it will chatter. Hence the suggestions above for power feeds.

I imagine a carbide insert parting tool might make a big difference on a small lathe too over HSS.

Just a Sparky said:

Re-grind the parting blade to ensure it is sharp, slow down the spindle speed and check for anything which could be reducing the rigidity of your tool. Make sure your carriage is locked down and gibs are properly adjusted. Minimize blade stick-out as much as you can. Parting blades are notoriously fussy on small lathes because they require a tremendous amount of rigidity to cut properly. Even a tiny little bit of swarf trapped behind the parting blade in the tool holder is often enough to make them chatter. A consistent feed is also needed. Too fast or too slow and it will chatter. Hence the suggestions above for power feeds.

I imagine a carbide insert parting tool might make a big difference on a small lathe too over HSS.

Click to expand...

Thank you good points.

Reducing the spindle speed and the feed worked well.

The screaming seem to be originating from the spindle bearings, particularly the rear one. Didn't seem to be any chatter in the tool itself or the tool holder area. I'm not sure if that's indicative of a problem in the spindle or when the machine starts to vibrate and resonate that's just where it manifests. It's bolted securely to the original South bend cabinet but it's not like it's 3,000 lb of cast iron.

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It sounds like it is rubbing on the metal (RE: the blade is too high). The parting tool holder holds the cutter at an angle - if you set the height at the tailstock (there is a height mark on the side of the tailstock spindle), then adjusted the cutter position, it is probably too high. If you're really cutting pipe, then your tools is out too far - it only needs to be a tiny bit more than the wall thickness of your pipe. Also make sure your cutting edge is very sharp.

And oil is not only your friend, but necessary while parting.

turn slow and feed hard is my motto when parting. Oh, and use a thin a blade as possible for the cut (more stickout = thicker blade). You want to make sure that you're making nice curls popping out of the cut. If you get thin shavings, slow the speed and up the feed.

Could be that your spindle bearings could use some shim adjustments too. Excessive spindle deflection can have this effect.

Take pictures before you remove any shims so you know how to return it as-found if tightening them up causes binding, overheating, etc. Sometimes it can be tricky hitting the sweet spot between .0007 and .0015 (iirc) if half-thou shims aren't available.

What does the grind on the cutoff tool look like.
Can't tell from the video but I'll assume the tool holder mounts the blade with a slight'uphill' angle. These holders are usually at or around the ideal 7 degree angle.
If so, grind the tool so it's almost 90 degrees vertically. It's likely your tool has too much angle and wants to dig in as you cut.

Another needed thing on parting is tons of lube. Like a constant flood it quantity of lube. In defense of your efforts, pipe is crap metallurgy and difficult to work with.

So cut your tool angle down to almost nothing, lube the hell out of it and report back.

I have a flimsy little 9 inch and with things setup properly I can just crank away parting on a steel bar 3 inch diameter and make the chips fly. Did I say you need to use lots of lube?

Oyeah,, As the tool holders usually have that 7 degree uphill angle to them, each time you extend the blade from it, the tip will go higher than the center of the spindle height. So you always have to check the height of your tool tip.

edit:
I've found that for low cost tooling these T shaped blades work very well. cut-off blades - ICS Cutting Tools
Click on the page 316 link.

B&C, Sir
Ahh cut off tools... You should be able to part stuff off at the same speed you turn it ( for the diameter). Cutting oil is your friend, get some. Sharp tool is a must. Don't be gentle on the feed.. The chatter is to to A: to light of feed B: wrong tool height C:tool dull or wrong geometry D: the material.
Fiddle with the tool height. Up down til it works ( cut off tools tend to have a rather shallow underside and tend to rub on smaller diameters) Do your self a favor and turn your compound so it's not 'hanging in the wind' That WILL cause vibration. Turn it 90° so it's supported by the cross slide.
Black iron pipe is notorious for being inconsistent and a bear to part off.. just saying but material makes a big difference in tool performance.
Hope this helps and if I can be of any assirance to you let me know.
Stay safe
Calvin B

As others have mentioned, lots of lube, or better yet coolant. One of the best things I did for my lathe was a flood coolant system.

For parting ferrous metals, I like the cheap carbide insert blades.

Try some grinding some rake on the tool, set at or just above centre, go slow and brush oil. Big chuck and back plate putting the work away from the front bearing dont help id imagine.
gl

I have always had trouble parting off. I found slow speed lots of cutting oil and a very sharp HSS cutting worked best for me. I started using my 6" rule (centered) between the part and the cutting tool to adjust the cutter height. bring your tool close to your part then hold your rule and just touch the tool to the rule, if the rule is straight up and down, then you are on center, if it is not adjust the tool up and down until it is. This also works for all cutting tools.
Ben