Broke a parting tool

This is my current parting blade tool holder and my set up.

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I have the compound at an angle for a better picture. In use the compound is inline with the cross slide. I lock the carriage in place and I tighten the gibs on the compound so that there is no movement on the compound. The only thing that moves is the cross slide. And I tighten the gibs on the cross slide as tight as possible while still allowing the cross slide to move. I never extend the compound slide past the edge of the compound base (wrong terms??) as shown in the middle picture and depending on the clearances the compound is set as far outboard as possible as in the bottom picture. The height adjustment screw which is locked in place acts as a support to keep the post on my QCTP from flexing.
 
One thing I noticed in you pic is that you have a live center on your part. Do not use a center, its too rigid not allowing the part to flex a bit. Remove the center just before you break thru. When parting my rpm is no more than 200, I feed by hand and lots of coolant, flood if you can.
 
I've found that when parting longer pieces, it helps to use a center. Just remember to take it out before the piece cuts completely off. With short pieces or disks, no center, of course.
 
Thanks to all!
I think my problem was caused by (for anyone following along):
1. Didn't sharpen tool. I assumed it was sharp out of the box.
2. Improper alignment. I used a "fishtail" and aligned it perpendicular by eye. I aligned it parallel by eye, but it may have gotten slightly out of alignment when I tightened it. I thought it was good, but I'll need to check it better. The video was very helpful. Thanks, BGHansen!
3. Too slow RPM.
4. Use more cutting oil. I would put some on, then cut, then put more on. It needs a steady supply.
5. Use tail stock until the part is ready to come off, or try not at all.
6. Tighten the compounds and make sure the tool post is not hanging out. Mine are loose due to age, but I think I can get them tighter.

I will sharpen the tool and see what happens. I'll try that before making a tool holder.
 
Jeff has a craftsman lathe. Virtually impossible to have a holder on the backside. He is pretty much limited to the front side. Mikey has educated me on the forces involved and how everything flexes that makes parting on a craftsman lathe difficult. To have any chance of success you need your setup as rigid as possible with a properly sharpened blade exactly on center.

When parting on the front side the carriage, cross slide and compound all want to lift on the outside and press down at the work. This flexing is what causes the blade to go below center line and into the work resulting in the work riding over the top of the blade. There are gooseneck tool holders designed to compensate for this flexing

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I bought some but they were too big to use on my lathe. So I have not used them and can not attest to how well they work. I have seen pictures online of gooseneck tool holders for a QCTP. I have thought about making one.

Jeff you just have to keep experimenting until you get a setup that works for you.

I found this when I searched for "gooseneck toolholders for lathes". Though you might like it:

I think I have something similar in the parts that came with the lathe. It had a short, broke parting blade in it.
 
When I align my parting blade I like to put the side of the blade against the end of the work at a slight angle.

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A piece of white paper on the ways sometimes makes it easier to see when the blade is flush against the work. I do it mostly by feel. With the tool holder loose I slowly advance the carriage towards the head stock until I feel the blade go flush against the end of the work. The blade is now square to the work and I tighten the tool holder to the post.

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If you go too far the tip of the blade will point towards the tail stock. It only takes a couple of tries to get this down pat.

The above pictures are not something that I am actually working on. I just put a round bar in a chuck to show the concept.

I have looked at that thread about making a goose neck tool holder and have done a drawing to fit on my tool post. Another project on the list.
 
One thing to look at is tool height.
I tend to run my parting tool a little higher then center line. There tends to be alot of leverage with a parting tool and when it engages the material can be pushed below center line of rotation which make the material try to climb on top of the tool tip......
 
From the picture you have more stickout than necessary. I'm guessing (hard to see in the pic) that you have 2 dovetails on your toolpost and one of them is facing the live center. If you turn the TP so that the flat side is facing the center you can reduce stickout by a half inch or so. Rigidity is the grail with parting. Once the tool flexes everything tightens up and "bang".
 
I've never broken a HSS cutoff tool. I can brake carbide inserts all day long. It's a dance between RPM and feed speed IMHO.
 
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