[How do I?] Parting with backlash

Hi fellas. These are a lot of great suggestions, and I'll give several of them a try. I thought, probably incorrectly, that backlash was the problem since there is less on the craftsman 109, and that lathe cuts and cuts without breaking tools. I'll try tightening up the gib screws and reducing the rake on the tool. I ran it upside down and in reverse on the Jet 1440 at techshop, since it has a di6 chuck mount and is safe. I've unscrewed a threaded chuck once, and no matter what anybody says, I am not trying that again. Even at only 200 rpm, things happened fast and can really go south. The tool is held in a purpose made block and is close to the hold down bolt so there is less of a lever arm and better rigidity. I found that things improved if I manually held the cross slide back as I was feeding it, but this isn't a good solution. Looking at the above picture, the cut outs have a lot less rake than my tool. I'll seek their geometry. I think there's a picture of the parting tool in the craftsman section. I'll see if I can find it and link it. Thank you for all the suggestions.
 
One thing I forgot to mention is that when I changed to a hss "T" section parting blade it cut like a hot knife through butter (well almost)
I've just had to part 6 of these sections
parting.jpg
and this is the swarf from them. Its an unknown steel of some kind.
parting-swarf.jpg
There is no way of eart the original flat blade cut like this and the old top slide would flex sufficienty to break the blades.
 
First your blade is too far out.

Choke it in to use enough to get through.

Next the area order the cutting edge or relief needs to be shallow to control the cut as with a radial arm saw a control cut blade makes a far better cut.

What may be happening is due to backlash the tool can be pulled into the work as nothing but the work is holding it OUT.

Making a controlled cut style cutter limits the action as it will rub if pulled in until break through.

Auto feed at smallest rate helps if you have it.

Experiment with cutting height may help too.
 
Hi. I tried reducing the rake and tightening up the gibs on the cross slide and compound. It helped a little, but there was still chatter, and the blade dug in again and snapped the tip off. I guess it was a bit my fault because I read on the web that carbide tips should be fed hard. It was being fed at substantially more than .002 per rev when it snapped. I already know what feed should be used with these saw blades, since I have used them successfully with a craftsman 109 and a Jet 1440 lathe. Something else is wrong. The blade was sharpened with a fine green stone followed by a coarse diamond slip. This has worked well in the past. Something else must be wrong.
 
Hi savarin. Your setup looks good, especially with those rolled up chips which I am familiar with. I have a couple of P-3 HSS blades like yours that I can try. I've only used them with the big lathe, but they worked well.
 
Hi Bob. There is intense vibration in the tool block when parting. I cannot figure out where it is coming from. When I grasp the tool block and shake it hard, the only thing that moves is the cross slide by the backlash. I found out that even if I tighten the 5 gib screws on the cross slide so that the crank becomes hard to turn, it starts to loosen. By the time the parting blade broke, it was back to the original state. So, I have to find another way to tighten the gib screws so that they do not come loose. It almost seems that the parting problem is backlash related, but the Internet seems to say otherwise.
 
when you get vibration on that big wide plunge cut slow the rpm's down. it going too fast. bill
 
or go faster and load up with cutting fluid. Where you are at isn't working from what you've written.
 
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