Endmill Pulling out, and lots of heat - Live Tool Lathe

[nickoalous09]

I am having some issues with a 5/8" endmill tending to pull out of the holder on my live tool lathe.

I am stuck with using ER32 collets to hold anything in a live tool on the BMT 65 Turret, so I cant simply get a better holder for milling.

Currently taking .025" Radial DOC at 3550 RPM (580 SFM)roughing at 150 IPM climb milling. Material is 1045 Steel. Im making round stock square basically. The max cut depth axially is 1.8" stepping up each pass as I cut off the radius of the stock making a flat side.

When assembling the tool into the holder, I am cleaning both the collet and tool shank with a cleaner (basically brake clean spray) and tightening the nut as best I can using a cheater bar, and I still have occasional tool pull-outs, especially when the cutter starts to dull.

Not all that surprising, but if the tool pulls out and falls into the bottom of the lathe, it will definitely chip the tool, and I am using a fancy, way too expensive, tool from Sandvik. I need to eliminate the pull-out issue.

Another thing Ive noticed is after running a single flat on a part, my live tool holder is quite hot. I cant imagine the heat is good for the tool holder.

Any help is appreciated.

 

[Orange Vise]

That's an aggressive cut for live tooled lathe. Reducing any or all the parameters will help.

Not all that surprising, but if the tool pulls out and falls into the bottom of the lathe, it will definitely chip the tool, and I am using a fancy, way too expensive, tool from Sandvik. I need to eliminate the pull-out issue.

I'm not following. You're saying the tool is pulling completely out of the holder and falling onto the conveyor?

 

[Milland]

If the live tool is getting hot, perhaps it's time for a rebuild. Has it done it since new?

You can "fake" an anti-pullout feature into a collet by using a small dowel pin (say, 1/32" x 1/4"), and grinding a cross-wise groove into the tool shank and the same area of the inside of the collet.

Obviously you have to be careful with geometry and depth, the grooves must allow the pin to sit a little above flush on the shank, but not bottom inside the collet. Use a diamond wheel on the shank, Dremel-style cutoff wheel inside the collet.

Done right, this will be virtually impossible to pull out, even with normal tightening of the retaining nut.

 

[EmGo]

If you want to spend more money, you can get opposite-hand end mills. For example, left-hand helix, right-hand cutting. Then they try to push deeper into the collet, which you can solve with a stop.

 

[Mechanola]

Im making round stock square basically.

The long contact surface causes the strong pull-out force. My suggestions:

• Use a large shell mill instead of small endmill, if possible
• Change to miller axis square to the lathe spindle axis
• Start with square stock, clamp accordingly
• Install a grinding wheel instead, if possible
• Grind square surfaces separately, if possible
• Change part design, if helpful

Where you can use a collet holder you can use a shell mill holder. Don’t know whether you have any.

Endmills are overrated. The practical machinist always starts with the biggest reasonable tool, then adjusts size downwardly. Been waiting a long time to find an opportunity to write that.

 

[Milland]

The long contact surface causes the strong pull-out force. My suggestions:

• Use a large shell mill instead of small endmill, if possible
• Change to miller axis square to the lathe spindle axis
• Start with square stock, clamp accordingly
• Install a grinding wheel instead, if possible
• Grind square surfaces separately, if possible
• Change part design, if helpful

Where you can use a collet holder you can use a shell mill holder. Don’t know whether you have any.

Endmills are overrated. The practical machinist always starts with the biggest reasonable tool, then adjusts size downwardly. Been waiting a long time to find an opportunity to write that.

I have to disagree here. The OP is working with a powered turret milling adapter with very small and closely spaced spindle bearings. So they've got very low stiffness and load capacity, relative to a regular VMC or HMC. Neither a facemill nor the milling spindle would live long in this application.

Grinding is out - too low SFM, too weak a spindle, too low HP, etc.

If the OP is stuck with this operation, a 5/8" endmill isn't a bad choice, relative to the capacity of the rest of the machine.

If my guess is correct and this is a Haas lathe, you can see the milling spindle (or similar) in the thumbnail and at 12 seconds in here:

The BMT65 Turret and Live Tooling for Haas Lathes - YouTube

 

[ViktorS]

Well if you are stuck with ER32 and want to maintain the surface finish of sidemilling with an endmill then all you can do is to reduce cutting parameters (if this is in a more production oriented situation). Especially reduce axial depth. Thats my tip anyway.

If you have the possibility you might use a short insert endmill/high feed mill to take facing passes from the radial direction instead of axially. If you need the side milling surface you can leave some small amount and just do a finish pass with the endmill.

Just throwing it out there..

 

[Mtndew]

Rego-Fix makes an anti-pullout ER collet.

 

[Micmac1]

5-6 Flute Endmills are notorious for pulling out of ER32 collets, especialy with aggressive parameters, assuming its a 5+ flute endmill? Id either lower speeds or lower speeds and switch to a 4 flute.

 

[CAMasochism]

Rego-Fix makes an anti-pullout ER collet.

We made our own where I work by making our own solid ER32 collets and drilling and tapping them for weldon flat endmills. It's not the best solution, but it works well enough.

If you have heat shrink tooling handy Pioneer and Iscar make heat shrink collets as well.

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[Milland]

If you have heat shrink tooling handy Pioneer and Iscar make heat shrink collets as well.

I tried heat-shrinking my collets on, but the damn slots just let the tool slip out again!

 

[Ox]

If the live tool is getting hot, perhaps it's time for a rebuild. Has it done it since new?

You can "fake" an anti-pullout feature into a collet by using a small dowel pin (say, 1/32" x 1/4"), and grinding a cross-wise groove into the tool shank and the same area of the inside of the collet.

Obviously you have to be careful with geometry and depth, the grooves must allow the pin to sit a little above flush on the shank, but not bottom inside the collet. Use a diamond wheel on the shank, Dremel-style cutoff wheel inside the collet.

Done right, this will be virtually impossible to pull out, even with normal tightening of the retaining nut.

Boy, there's an idea that I never heard of before!
Most guys would never doo that to their collets, but ... whatever works!

I have some TG collets for capturing Welden shanks, but most don't have the notch anymore. (for strength reasons if nothing else)
Don't know if they make ER's with that option or not?

If you want to spend more money, you can get opposite-hand end mills. For example, left-hand helix, right-hand cutting. Then they try to push deeper into the collet, which you can solve with a stop.

LH mills are only for side milling.

I am having some issues with a 5/8" endmill tending to pull out of the holder on my live tool lathe.

I am stuck with using ER32 collets to hold anything in a live tool on the BMT 65 Turret, so I cant simply get a better holder for milling.

Currently taking .025" Radial DOC at 3550 RPM (580 SFM)roughing at 150 IPM climb milling. Material is 1045 Steel. Im making round stock square basically. The max cut depth axially is 1.8" stepping up each pass as I cut off the radius of the stock making a flat side.

When assembling the tool into the holder, I am cleaning both the collet and tool shank with a cleaner (basically brake clean spray) and tightening the nut as best I can using a cheater bar, and I still have occasional tool pull-outs, especially when the cutter starts to dull.

Not all that surprising, but if the tool pulls out and falls into the bottom of the lathe, it will definitely chip the tool, and I am using a fancy, way too expensive, tool from Sandvik. I need to eliminate the pull-out issue.

Another thing Ive noticed is after running a single flat on a part, my live tool holder is quite hot. I cant imagine the heat is good for the tool holder.

Any help is appreciated.

If it were me, I would run a rougher (corncob) endmill in there.
I run roughers as much as possible, especially in the live tooled lathes.
They take less trq, and they will beat the holder up less as well.
If you are just making flats, then you don't need a finisher side anyhow.
I save up my used roughers that I use for this app as they typically only use the bottom 1/4", and then I get them repointed, once, or maybe twice more.

Option B would be to stuff a small face mill in there.
IDK if you can buy a face mill adaptor for your tool heads, but a cpl of us have made our own.
Came up in a thread just a few weeks ago.


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Think Snow Eh!
Ox

 

[Milland]

Boy, there's an idea that I never heard of before!
Most guys would never doo that to their collets, but ... whatever works!

Ox

Sometimes creative madness just overwhelms me...

ER collets (decent ones) are so dang cheap now that a little surgery shouldn't be scary. I'd probably not bother with any cutter smaller than 1/2", and you might need to shrink the dowel with smaller shanks.

 

[michiganbuck]

I must be really old-fashioned because I still remember our instructor saying for heavy milling with end mills you use an end mill holder with a piggy-back set screw, or the cutter will pull out.

Perhaps a new design end mill with having a female screw thread at the tail end so one might put in a screw and washer to be a pull stop in a collet..but it would likely still try to turn in the collet.

Imagine a horizontal mill cutter with not having a key..you would need to take light cuts only.

 

[Ox]

I must be really old-fashioned because I still remember our instructor saying for heavy milling with end mills you use an end mill holder with a piggy-back set screw, or the cutter will pull out.

Perhaps a new design end mill with having a female screw thread at the tail end so one might put in a screw and washer to be a pull stop in a collet..but it would likely still try to turn in the collet.

Imagine a horizontal mill cutter with not having a key..you would need to take light cuts only.

Solid carbide end mills - HAIMER

--------------------------

Think Snow Eh!
Ox

 

[Milland]

Perhaps a new design end mill with having a female screw thread at the tail end so one might put in a screw and washer to be a stop in a collet..but it would likely still try to turn in the collet.

Kennametal has grooves in the shank of their "SAFE-LOCK" endmills that (working with pins in the holders) basically do screw the endmill in for security.

High-Performance Solid Carbide End Mills • HARVI™ - HARVI I • UBDE • F4AS.. WM-WX-WL • Unequal Flute Spacing • With Neck

Not seen a lot of them out in shops, may be slow to catch on due to proprietary holders and grind, not to mention little flexibility about where you clamp. My "pin in shank" suggestion is a little work, but lots of freedom.

[Edit: missed Ox's post]

 

[michiganbuck]

We used to grind a Weldon stops and pull or push it if right or left hand, also whistle stops.

Course diamond sandblasting carbide end mills with perhaps a 36 grit would be good, but never saw and done that way.

Just a 36 or 46 grit grind finish would help a carbide end mill from pulling so easily.

I used to use a 100 grit diamond wheel to make a file out of a Norbide stick, you could feel the ridges with your fingernail, I used them for the final swipe on a knife-edge and for de burring work. Block-in the Norbide and long travel only with a fresh sticked diamond wheel. Down feed .0002 to the grind direction and long pass with no cross feed..no down on the climb direction...four .0002 wet passes is enough.

 

[Milland]

This is an interesting read: NEW ShrinkLOCKED Technology for Shrink Fit Holders to Improve Gripping Power. - NEXT GENERATION TOOLING

It's either a CBN or diamond grit embedded in the shrink holder bore, but held to a very close degree to maintain tolerances. May even be finish ground after coating to ensure uniformity at a small cost in holding power (but still better than bare).

Same approach could be taken with collets, I bet Techniks is working on it...

 

[Ox]

Actually, I think that there is someone selling shrink holders for ER live tools, but IDK that they were going this big?


------------------

Think Snow Eh!
Ox

 

[michiganbuck]

Wow! ..I had to delete that/my new product idea..hope nobody saw it.

Please keep it on the QT if you don't intend to market it.

I have one invention developing now and likely not able to get to this one for a number of months.

Anyone wants to partner up, just send me a half million and we will see what we can make of it.