Milling 101, sanity check...

[Davek0974]

Am I getting this??? That slot is 1 1/8" deep....blind slot (not a through slot)???
If so, that is a hell of a cut. I'd be plunging a whole whack of steel outta that before trying to mill the slot.
I'd also be blowing the chips out as I went to avoid recutting chips.
But that's just me
Russ

No its a through slot 1 1/8" deep x 0.875" wide x 4 1/2" long.

I wasn't taking the whole cut in one pass, it was maybe 1/8" DOC, but it does appear the speed was a tad low and the feed rate a bit harsh!

I will be trying my 6-flute roughing cutter on the next one, with some coolant this time:-)

There is about 1mm back-lash on the bed x-axis, i.e. I can pull the bed 1mm by hand, so i guess that was not helping.

Dave

[Carld]

Dave, roughing endmills work great for full depth of the cutter. That is if the rougher has 2" of cutting flute it will cut 1 7/8" with 1/8" sticking out top and bottom. a two, three or four flute endmill will not do that. A two, three or four flute endmill will always have some jump when machining. The harder you feed it the more the jump. With a roughing endmill you will hardly feel any jump and you will know if you are feeding to hard. I use a cup of oil and an acid brush and apply the oil above the cut and let the flutes feed the oil down the cutter.

Be carefull to keep the brush from getting in the cut. It's real exciting when the brush goes between the cutter and the work.

If you use a mister with water based coolant you can cut unbelieveably fast.

If your endmill you used to cut the slot is not blue or dull I would not discard it. If it is dull save it with others and take them to a gringing shop and have them resharpended. Many times it's cheaper to have 1/2" and up endmills resharpened than buying new.

[Davek0974]

Thanks all,

Yes the cutter looked ok so i put it on the 'look at that later' pile of stuff.

I did use the roughing cutter on the last one and was much better, more cut, less agro, much faster. Lots of coolant to flush the chips out.

I cleaned up the roughed sides with a slab-cut on a four-flute at full depth with light DOC and the result was excellent.

Lessons learnt.

Dave