Help Parting On A Curve

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umahunter

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I'm parting 2 inch solid aluminum with a 3/32 t style hss blade and as you can see I'm curving I have a filling I may be going to fast but thought I would see if I'm missing anything else as you can see I've got quit the curve 20150613_002705.jpg20150613_002606.jpg20150613_002606.jpg20150613_002705.jpg 20150613_002705.jpg
 
Make sure your tool is perpendicular to the work. You might want to keep the tool as short as possible even if you have to adjust it out several times. Wd40 can help.
 
Lock everything as tight as possible in
cluding carriage, tool post, tool holder, door to the shed to keep the dog from distracting you etc.I have had similar experiences with parting and the problem in most cases was a parting blade that was not ground square and pulled the toolpost in the direction of the leading edge. I have also found that in parting feed in so fast that it makes your eyes squint then feed a little faster. As you near the center even faster. Use this advice at your own risk.:chunky:
John.
 
Like outhers to much over hang and tool not square to the part And lock down. It also looks like your blade wasn't sharp. Also make shure it is dead on center.
 
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I've seen this happen when the blade is not precisely vertical in the holder. Even if you get the blade perpendicular to the work it will steer and cut a curved path. Are you using that Shars blade with the chip groove on top? If so, be sure it is ground square across the face and is very sharp.

One other thing that might be contributing to these results is too slow a cutting speed coupled with forcing the feed. This will cause the blade to bend if you use a lot of force to feed the blade into work that is going too slow. I suggest increasing speed to about 60% of turning speed and feed in as fast as you need to maintain a slight positive feel at the tip. It will cut very easily when you get the speed and feed just right. Keep the cut lubed with WD-40.
 
Good advice above. Tip must be perfectly sharp and square to the blade. As soon as you loose a corner it will deflect blade away from dull corner. If tip is not square to the blade it will plow sideways. If there is any welding of aluminum on the tip it will have the same effect so must avoid heat at all costs. Using lots of lube to keep tip and alu cool might help. Parafin, heating oil, or kerosene might work better than WD40. Alas some types of aluminum are so gummy that parting is a nightmare even when done right. Makes the option of hacksaw and then facing the part look pretty good.
 
One thing I learned recently is to increase your RPM. For instance I was parting 1" aluminum at 360 RPM because it makes me nervous from all the bucking and I finally tried at 600 RPM and it cut like a dream without the bucking. Also on a larger diameter maybe cut a step on the waste side so the opening is wider and minimizes binding.
Dave
 
to me the piece you cut off looks like the tool was loaded... IE not enough lube or not sharp and pushed in too hard... Now I normally do things by feel and I have only just recently started cutting aluminum but I personally like running the chuck as fast and turning in the tool by hand to the feel where you can feel the cut yet not enough pressure so it feels like your using a butter knife.
 
1. tool not perpendicular
2 cutting edge not parallel

probably a bit of both
 
Checking your deflection on the tool and holder if it's flexing when pushing in its not sturdy enough or the compound isn't locking tight or just tool holder is bending .thicker blade may cut better if all else fails.
 
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