Milling Slots

HBilly1022 said:
Thanks Ted, next time I will slow the rpms down and give that a try. Might have to look into to a mister now.:wink: This hobby just keeps adding up.

Ted, you might recognize the slotted parts. I just added the pic.
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Yes! Looking good. Looks like you've got quite a bit done. You've gotten varying recommendations for speeds; you'll have to play and see what works best for you and your setups. If I remember correctly, when I made these same parts, I drilled a hole at each end setting my table stops. I think I went back and forth dropping ~0.050 per pass running either 400 or 600 RPM (don't remember exactly which pulley groove I used), used a mister and hand fed. I used the same HSS end mill for all the parts and the cutter is still nice and sharp. I'm retired with more time than money so I try to stretch as much tool life as possible. You just need to find what works best for you...

YMMV,
Ted
 
I use at least a 4 flute end mill, the more flutes the better. A starter hole is optional or just go back and forth with the cutter. Be careful when cutting the slot, the cutter will favor one side more than the other. Make dial settings or whatever to note the ends of the slots. When the slot is open. Then go over the entire slot with a whisper climb cut for a nice finish…Dave
 
Looks like opinions are all over the map, full depth /not full depth, plunge / don't plunge, faster / slower, 2 flute / 4 flute. But there are 2 constants; feed by hand and use air. I was power feeding but occasionally stopped the power feed and fed it by hand, to feel if I was going too fast.

Next time I will try full depth (probably drill this) then use the top of the end mill, use air, slower rpm and hand feed. See where this takes me. I did note that when I was brushing on lube, the chips would build up in the slot, even when it was a full depth cut and the chips could exit out the bottom.

I think I will also give the chain drilling a try. As Bruce stated, drill bits are way easier to sharpen. I recall chain drilling a slot before but there was something I had an issue with. I think it was vibration. This time I would use the top of the end mill and snug the mill head up close to the work, so there is minimal quill extension.

Thanks for all the help and suggestions. Lots to work with.
 
HBilly1022 said:
Next time I will try full depth (probably drill this) then use the top of the end mill, use air, slower rpm and hand feed. See where this takes me. I did note that when I was brushing on lube, the chips would build up in the slot, even when it was a full depth cut and the chips could exit out the bottom.
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I think you are doing the right thing... trying different methods and see what the results are. This is how we learn. One word of caution though, the more material you take depth wise, the more the tendency for the end mill to walk. This condition gets worse the duller your end mill is. Just something to keep in mind. Sometimes this won't really create a problem, but other times it can depending on the fit, alignment, etc..

Ted
 
[QUOTE="Technical Ted, post: 537047, member: 43849"One word of caution though, the more material you take depth wise, the more the tendency for the end mill to walk. This condition gets worse the duller your end mill is.[/QUOTE]

Ted, for my own education, can you expand on this? I don't understand what you mean by walking.
 
Walking is when an end mill bends and climbs off to the side rather than cut in a straight line. It gets worse the duller the cutter is because it doesn't cut freely and the added friction and pressure makes the cutter climb more.

Ted
 
Technical Ted said:
Walking is when an end mill bends and climbs off to the side rather than cut in a straight line. It gets worse the duller the cutter is because it doesn't cut freely and the added friction and pressure makes the cutter climb more.

Ted
Click to expand...

Is this behavior when you use the end/cutting tips only? I have seen something like this when the cutter is dull but not when it is sharp and certainly not when side milling.
 
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