Parting Question: Seems Feed Is Really Fast.....

TomS said:
I have the same holder and parting blade. The problem is the holder is not made for that type of parting blade. The holder has no relief for the top portion of the blade that is wider than the body portion. What happens when you install the blade flush with the holder the blade is not held vertical and it is somewhat tilted to the side. What you need to do is mill a relief slot in the holder so the body portion of the blade can be mounted flush to the holder. Hope I'm making myself clear. I can take a picture of my holder in the morning and post it if that will help.

Tom S.
Click to expand...

Yep, I understand. I have looked at that before. I haven't milled the slot yet, but maybe it's time to do so...
 
Something my retired machinist friend told me was to support the workpiece by putting a spacer (flat one side centered the other) against the trued end, with a live center in the tailstock.

Works for turning as well but when parting just go 3/4 through and then remove the support.

He supports most work, reckons it doesn't hurt to do this even without too much stickout from the chuck on a small lathe as they need all the help they can get, yes it goes against usual parting wisdom but I've tried it a couple of times on larger diameters with good results.

When altering things to try and get better results, only change one thing at at time and test again before trying the next change, so you'll know what the problem was.

Bernard
 
TomS said:
I have the same holder and parting blade. The problem is the holder is not made for that type of parting blade. The holder has no relief for the top portion of the blade that is wider than the body portion. What happens when you install the blade flush with the holder the blade is not held vertical and it is somewhat tilted to the side. What you need to do is mill a relief slot in the holder so the body portion of the blade can be mounted flush to the holder. Hope I'm making myself clear. I can take a picture of my holder in the morning and post it if that will help.

Tom S.
Click to expand...
Tom, can you post that pic? I would like to see it. Thanks.
 
I've found that holding a chip brush full of lube in the slot with one hand and feeding the cutter with the other hand helps immensely with chatter and squealing issues. It needs to be continuously lubed while you're cutting.
 
One random thought.......there is an anomaly that runs around shops randomly stirring up trouble. I always tell my guys this when they struggle with something that has been done before. Nine out of ten times you can do things the same way, then there is the day when nothing works like it is "supposed" to! Usually figure it out, but............;)
 
Great white,
Just another thought but how is the compound set when you get chatter? You mentioned locking the gibs on the compound but it is also a good idea to crank the compound back as far as practical to get minimal overhang of the compound.
I use the 207 parting holder with a tapered blade and get good results on steel and brass when the sharp blade is vertical, square to the work and on centre.
It does seem to like a hungry feed.
Mike
 
I remember the first shop I was a operator in. There was a senior machinist who for some reason make a series of small parts with cutting groves. I can't recall why he couldn't part off these pieces but came over to the horizontal bandsaw area they used to cut material. You can guess what happened when the shaft slipped during the first cutoff. He lost a little tip of his thumb but bled like he lost his finger.

I had a blade that was straight not tapered that may be your problem. If the holder was built for a tapered bottom slot I agree with Tom.

Be careful and I hope you get this problem fixed soon
 
I think your setup is just not rigid enough for good parting. I had an old Logan that wouldn't part. I replaced the compound with a solid block of junkyard steel with a slot milled in it to hold the parting blade. Cut fine after that in all metals. I did the same thing with my 12 x 36 Grizzly. It already cut well but really cuts like a champ after eliminating the compound.

LOGAN TOOL HOLDER.JPG DSC_1074.JPG .
 
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