First real part...parting woes!

[BrianT]

Been awhile since posting so I thought Id share the first actual part I made on a lathe that actually will serve a purpose...drawbar spacer for the Atlas 618.
Everything went well until I decided to try to part off, way too much chatter. I have the qctp from LMS and the blade type cutoff tool that fit in the tool holder. I will read up on the parting issue as I know there is much info here on this. I already understand I was running too fast to part off. I've only had this lathe running for a couple weeks so overall I was happy with the outcome. So thanks to all who contribute their knowledge here, without that I do not think I would have gotten this far so quickly. Any recommendation on alternative parting tools I would be interested to hear.

Lastly here is the 618, got it 2 years ago in a box of pieces and finally got it running with all the help offered here.

 

[Mystery2]

Parting with a small lathe just plain sucks .
I use the t type parting blades and they work pretty good .
A lot less chatter , at least with my g0602 I get a lot less chatter .
I still can't reliably part anything over 1.5" diameter in steel .
Keep the tool sharp and be a little aggressive to keep underneath the chatter might help some to .
I bought a bandsaw just so I could keep parting to a minimum because it sucks

 

[BrianT]

Thanks for the info. I will get some of the t-type. I was using a generic plain blade from an assortment pack. I ended up sawing the end off and faced that end. With all the chatter I was getting the tool post got loose and things just got worse from there...so the t-type is worth a try...

 

[T Bredehoft]

Don't forget, croud the blade into the work. It's scary at first, but the only way to go.

 

[BrianT]

Don't forget, croud the blade into the work. It's scary at first, but the only way to go.

Does "croud" mean kind of forcing? I was forcing it some, kind of afraid to try it again as I dont want to damage anything and that was the direction it was going to go. I was at the same speed I faced/turned at when I tried parting which is one problem I believe. I also had the cut off blade extended much further than it likely should have been. Everything else went so well I just went to part off with out lots of thought.

 

[Ken from ontario]

I also use a bandsaw when I can or should I say whenever it's more practical even though I can use the parting tool I made for my mini lathe but with a bandsaw there's less drama and it's quick.

 

[Rooster]

Greeting's Brian, i have the same wonderful lathe. All i do is put it in back gear and it works great. Blade must be on center height and snug up all gibs.

 

[Bob Korves]

If parting goes bad, just stop and hacksaw through the remainder of the cut, then face the part smooth. Chatter is caused by looseness and lack of rigidity, make sure everything that slides is adjusted for snug fits and everything that can be locked down is locked down. See if that helps...

 

[westerner]

Don't forget, croud the blade into the work. It's scary at first, but the only way to go.

Blade must be on center height and snug up all gibs

Brian, I feel your pain. My lathe is your lathe's big brother, quite worn. The chatter was scary! Very recently, I decided to follow the advice of Mr. Bredehoft and others here, and just PART THE DANG THING OFF. Good sharp tool, as thin as you can find, square and centered, minimal overhang. Then, WIND THAT SUCKER IN! You will find a feed rate that minimizes or eliminates the chatter, but it is MUCH, MUCH faster than you think is possible. After the first time I did this, I was in disbelief! So I moved over, and did it again, just for fun. And that was so much fun, I did it again!

 

[ericc]

One needs to have some common sense when doing the "croud" thing. If it is chatter, that can be helped by increasing the feed rate. If the tool is grabbing, this can lead to a crash and broken and flying pieces. I have encountered both situations, and it is hard to tell the difference. One good way is to find a nominal parting feed rate and make sure that you don't exceed it too much. For example, 0.002" per rev. If the spindle speed is 200 rpm, this translates to 0.4" per minute. You may try bumping this up to 0.005" per rev, which would be 1" per minute. Do not increase it to 10" per minute (1" in 6 seconds) just because someone tells you to cram in the tool. There is something wrong. Probably something is loose, and if you cram the tool in at this fast feed rate, even though "fast feeds are good", something could break.