Milling Problem

Slow it down! Get the RPM down to around 175-225 and you need some kind of cutting fluid to help. If that is a piece of 41xx and heat treated, you need to cut the RPM's in half, just my rule of thumb I use.

Thanks Ken. I'll give the slower speed a shot on the next attempt plus I'll brush on some of the Rapid Tap fluid until I can get some proper cutting oil.

Pretty sure it's not heat treated steel. Not positive though. I can easily file this, even after milling it.
 
Rapid Tap isn't bad cutting oil. I have some and I use it for that since I decided I like Tap Magic better for tapping.
 
Bob; Only problem with that is, if I damage the sides I have no way to sharped them (yet) and the end mill will be useless then. I can easily sharpen the ends though.

Jeff; please explain "back rake". Is that the primary cutting angle or the radial angle from the edge to the center?
I don't think the metal is hard because I can easily file it.

The back rake an angle away from the edge of the cutting tool.it's clearance. The edge should be relatively flat at the tip, but probably 1 degree from flat, then after 1/32nd it should be more like 5 degrees. This is necessary so you don't overheat the edge by dragging it across the metal. There are probably a few people here with better geometry numbers than my guesses, but you want strength in that edge so a very modest angle, then you want a more aggressive angle since it is not doing anything and you don't want chips or uncut metal if plunging being caught in there and dragging
 
Success!!!! :cheerful:

I sharpened one of the end mills again but this time kept the landing much smaller. I reduced the RPM to 215, reduced my feed rate and used quite a bit of Rapid Tap and voila ....... I'm back in business. I cut one new flat from scratch then went back and finished up 3 others and got most of the way through a 5th flat before I started getting shaking / heavy vibrations. Stopped for the night and will resharpen the end mill tomorrow before finishing off the flats. Then I'll take a pic just to prove it really happened and to show all of you what your input allowed me to do. THANKS for all the help!!!!!

Edit. Brino posted while I was typing. Thanks Brino and that is a great reminder to keep in the shop. Things can go very badly in an instant. I've got a pic of my finger after it touched the grinder a while back. I'll see if I can find it and put in the same thread as yours.
 
A simple explanation may be found here http://www.harveyperformance.com/in-the-loupe/combat-chip-thinning/

However climb milling is difficult on a manual machine, not impossible but will take some effort and planning.
You will find that climbing results in superior surface finishes and less tool wear. Please note that climbing on a manual machine can end in tears so plan ahead.
 
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I agree with Wreck Wreck that climb milling can be "tricky"... If you have any slop in your lead screws it can be a quick way to lose a cutter. It seems to be even more tricky when running cutters at slower speeds. They seem to grab and climb more and you can say goodbye to the corners of the mill or maybe even half the cutter! :eek:.

I usually only climb mill while taking very light finishing cuts where I want a nice finish. You usually can get away with this.

So, I would suggest anyone new to machining to avoid climb milling, unless maybe you're running a nice, tight CNC with feedback control or a manual machine that has a back-lash elimination set up and have it properly adjusted.

YMMV,
Ted
 
I have a lot of backlash in my machine but did manage to get most of the milling done using climb milling. I kept the DOC to 0.050" for most of the work. I tried some 0.090" DOC towards the end but I was getting some scary feedback and decided to stop and regroup. Will resharpen end mill and finish the job with small cuts.

Ted, what do you consider a light finishing cut? I'm asking because I don't know what is considered appropriate.

Wreck - thanks for that link. I have been milling with about 75% of the cutter engaged in the cut and will try 50% on the next run. By the way, after I reduced the speed, feed and used lube I didn't get any more of those long strands.
 
Success!!!! :cheerful:

I sharpened one of the end mills again but this time kept the landing much smaller. I reduced the RPM to 215, reduced my feed rate and used quite a bit ...

Hi. What does "landing" mean? Is it the same as "land"? I was only familiar with primary and secondary clearance. So, is landing the small flat before the primary clearance?
 
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I've also found chinese endmills to be disappointing for use on steel. Buying good used lots of USA mills on Ebay works for me and saves $
Mark S.
 
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