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Agreed that Weldon & ER40 are going to grip tighter. But...is it possible in an R8 w/o slipping or no? If y'all's suggestions are implying that it isn't possible: that's fine; I'll know never to attempt it again 
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Larger endmills pulling out of R8 collet
- Thread starter keeena
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If a .200” cut is pulling the tool from the collet, try it at .150” and see if the same condition occurs.
I have overzealously pulled an endmill or 2 while pushing the limits .
Clearing the chips out and sharp tools are incredibly important
I have overzealously pulled an endmill or 2 while pushing the limits .
Clearing the chips out and sharp tools are incredibly important
Same here. Tightened either by hand or the power draw bar. I run my drawbar at 80 psi, and don't let it hammer even close to the count of three. Zero slippage on end mills up to 3/4". May want to blue up a collet and see if you have good mating contact with the spindle.
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I must admit I have had a 3/4" end mill slip in a Bridgeport machine. Fortunately, only 1 time, and not on my machine. When it happens your heart sinks. You just hope that you didn't go beyond the final depth and reassess. In my case the culprit turned out to be a cheapie collet with a damaged thread. The power drawbar pressure was low enough that it would only tighten to the damaged spot. I probably should have checked things closer, but I was in a hurry.
As a point of reference Bridgeport recommends the largest end mill to be used in a collet on a Series I machine is 3/4". Beyond that the collets are so thin they don't have the holding power to cut hard or tough materials. Weldon style tool holders are the best for 3/4" and larger end mills. I do have mills up to 1 1/2", but only use them in a tool holder, and only on plastics, aluminum and other soft materials.
As a point of reference Bridgeport recommends the largest end mill to be used in a collet on a Series I machine is 3/4". Beyond that the collets are so thin they don't have the holding power to cut hard or tough materials. Weldon style tool holders are the best for 3/4" and larger end mills. I do have mills up to 1 1/2", but only use them in a tool holder, and only on plastics, aluminum and other soft materials.
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Ive done some pretty ignorant things in my years, but having anything other than a carbide endmill move in an R8 is a rarity for me.Agreed that Weldon & ER40 are going to grip tighter. But...is it possible in an R8 w/o slipping or no? If y'all's suggestions are implying that it isn't possible: that's fine; I'll know never to attempt it again
I also wouldn't put a 3/4" endmill into the "large" category, but that's just me.
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- Jun 10, 2019
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OK, sounds like it should work fine. Bluing up might be in order; maybe buy a quality collet.
Any other thoughts about F&S? I think I was in the ballpark of FSW's recommended chip load (fz 0.0014); just had the feed & RPM dialed down accordingly. I was a bit hesitant to run at the #'s FSW was suggested. What would you guys suggest?
To be precise about what is happening: the EM slowly (over the course of the cut) creeps out. It never stalls or spins in place. In this project: maybe crept out a total of 3/8"-1/2" over a 6" long side milling cut. Mill has a Prototrak a 2-axis control and ball screws. Same thing happens conventional and climb milling.
Any other thoughts about F&S? I think I was in the ballpark of FSW's recommended chip load (fz 0.0014); just had the feed & RPM dialed down accordingly. I was a bit hesitant to run at the #'s FSW was suggested. What would you guys suggest?
To be precise about what is happening: the EM slowly (over the course of the cut) creeps out. It never stalls or spins in place. In this project: maybe crept out a total of 3/8"-1/2" over a 6" long side milling cut. Mill has a Prototrak a 2-axis control and ball screws. Same thing happens conventional and climb milling.
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- May 7, 2023
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Maybe tighten the drawbar a bit more or look for wear/canted threads on it.
Also, all that stick out on your quill is not helping anything and generally bad for your machine.
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- Jun 10, 2019
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Yep, aware that quill stick-out can affect milling due to rigidity / runout. Due to the machining ops being CNC-ish the EM started over the workpiece. For the other side I started the program at the side-milling portion only and so I could choke up on the quill. The knee doesn't have a readout so I can't easily incorporate into the ops. FWIW: didn't seem affect finish, but point is certainly valid.