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End Mill Pull Out

HSM_CHIEF

Aluminum
Joined
Aug 2, 2017
What’s the best way to prevent end mill pull out? Currently I’ve tried a .500 inch hydraulic holder and it pulled on me.. do Er collets provide more gripping power? I’m running high speed tool paths in mostly 4140 what’s the best tool holder to prevent this? And also is there anything I should watch out for that would cause end mill pull out like re cutting chips from improper chip evacuation? We’re ordering a milling chuck which I hope will hold better. Just wondering what everyone els is using for tool holding? Thanks
 
TG collets provide a way better grip than an ER will.

secuRgrip from Rego fix might do it if you have a few main sizes you use for roughing.

secuRgrip for ER | REGO-FIX

They have a special ER collet with grooves in it, and a small grooved piece that fits in the weldon? flat of endmills so you have pull out resistance similar to a sidelock.
 
I actually just tried a side lock the other day and it did pull out... I believe it was my fault tho I didn’t have the flat bottomed out on the set screw so it ended up pulling out about .060 until it hit the top of the flat.
 
TG collets provide a way better grip than an ER will.

secuRgrip from Rego fix might do it if you have a few main sizes you use for roughing.

secuRgrip for ER | REGO-FIX

They have a special ER collet with grooves in it, and a small grooved piece that fits in the weldon? flat of endmills so you have pull out resistance similar to a sidelock.

Hmm interesting I’ve never heard of these I’ll have to look into it! Thanks!!
 
I tried about everything and found that plain old sidelock is the best option.

Big plus is that in is normally much shorter and slimmer than for example TG

A thing to watch though is the screw must sit on the walls of the V not on the bottom. IOW there should be no up and down play.
 
I tried about everything and found that plain old sidelock is the best option.

Big plus is that in is normally much shorter and slimmer than for example TG

A thing to watch though is the screw must sit on the walls of the V not on the bottom. IOW there should be no up and down play.

I've been wondering this, and you would be the guy to know... but could our feed/speeds calculator give us lb-force value for the pullout potential of a cut?

This is especially critical on BT30 machines where it's totally possible to snap retaining knobs and ruin spindles. It would be cool to have a quantified number instead of just winging it.
 
I've been wondering this, and you would be the guy to know... but could our feed/speeds calculator give us lb-force value for the pullout potential of a cut?

This is especially critical on BT30 machines where it's totally possible to snap retaining knobs and ruin spindles. It would be cool to have a quantified number instead of just winging it.

You can compare cutting force value that the calc generates to the max gripping power of the chuck.

If I remember correctly you need at least 3 times more gripping force than the expected cutting force.

The number to look is torque BTW.
 
You can compare cutting force value that the calc generates to the max gripping power of the chuck.

If I remember correctly you need at least 3 times more gripping force than the expected cutting force.

The number to look is torque BTW.

Since I'm bad at physics; does the torque value relate 1:1 to tool holder/pull stud force?

So if I see a 200lb_ft torque value, that translates to 200lb of pullout force on the spindle (and, I would guess, 200lb of pull-up force on the workpiece?)
 
Since I'm bad at physics; does the torque value relate 1:1 to tool holder/pull stud force?

So if I see a 200lb_ft torque value, that translates to 200lb of pullout force on the spindle (and, I would guess, 200lb of pull-up force on the workpiece?)

Not really.

It is not really the pull out force that causes the endmill to come out but the combination of torque and down force where torque plays the major role.

Tool holder manufacturers post Torque number as the measure of their gripping force. Usually it is posted in N-M

You have to compare your calculated Cutting Torque value (HMSAdvisor, for example, does output that) with that number.

It is true that vertical pullout force also increases the risk of pulling out. Especially with high helix endmills. This is why I mentioned x3 safety factor.

That is regarding endmills in tool holders.
I did testing with Shunk hydraulic holders and found it to be true.

I have no idea how machine manufacturers rate their spindles regarding maximum torque and pullout force they can handle.

An endmill with 45 degree helix will direct half of the cutting force downwards. But it is usually not enough to pull the toolholder out of the spindle. Not for CAT 40 at least
The force on the pullstud is measured in at about 3000 pounds. Not sure about 30 taper.
 
I have some very high quality Schunk, hydraulic chucks and the endmills pull easily also, they do not have the clamping force that others do. My go to, is my milling chuck for those applications. As others mention a good ole weldon flat holder using the flat on the carbide shank will always work, however the runout and vibration damping of those holders is not as good as milling chuck, so tool life will suffer, (slightly).
 
I have some very high quality Schunk, hydraulic chucks and the endmills pull easily also, they do not have the clamping force that others do. My go to, is my milling chuck for those applications. As others mention a good ole weldon flat holder using the flat on the carbide shank will always work, however the runout and vibration damping of those holders is not as good as milling chuck, so tool life will suffer, (slightly).
Yeah we just order a milling chuck to try out I’m sure this will be the best bet. Like you said it’s more rigid and tool life should be slightly better
 
What’s the best way to prevent end mill pull out? Currently I’ve tried a .500 inch hydraulic holder and it pulled on me.. do Er collets provide more gripping power? I’m running high speed tool paths in mostly 4140 what’s the best tool holder to prevent this? And also is there anything I should watch out for that would cause end mill pull out like re cutting chips from improper chip evacuation? We’re ordering a milling chuck which I hope will hold better. Just wondering what everyone els is using for tool holding? Thanks
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most companies will sell end mills with weldon shank flat if not most resharpening services can put weldon flat on. be aware you cannot easily grind a flat on carbide with aluminum oxide grinding wheels. usually got to use wheel made for grinding harder carbide
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when you put end mill in set screw tool holder pull out all the way to bottom out notch and tighten with allen wrench with a pipe on it to allow higher torque. usually higher torque over time will increase tool runout cause you make the bore oval shaped over time. dont hurt to use a torque wrench as 2 different operators can have very different ideals on what is tight
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use bigger end mill and use a roughing end mill when roughing. the wavy edge helps with vibration. its the pounding action that loosens things up. which be aware you can pull a part out of vise too even if end mill stays in the holder
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high cutting forces sometimes easiest thing is to ease up on feeds and speeds but mostly ipt of feed. or use big carbide insert mill which can rough with out problems. helical mill comes in all lengths, picture shows one bolted on a longer tool holder.
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bigger inserts can take more ipt feed. quite normal for bigger inserts to take .008 to .015 ipt feed. usually harder materials less ipt but always big inserts can take 200% or more than a end mill can take. you rough and finish with separate cutters
 

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I like short side lock endmill holders for aggressive cutting. A weldon shank or a quick flat on grinding wheel has been the tool that rarely pulls out and gives best tool life.

Better finishes or need to tickle a surface...collet holders work well.
 
I actually just tried a side lock the other day and it did pull out... I believe it was my fault tho I didn’t have the flat bottomed out on the set screw so it ended up pulling out about .060 until it hit the top of the flat.

I always pull my endmills out of the the holder, as I tighten the last 1/8 turn on the set screw.
It helps "preload" the setscrew against the top of the Weldon Flat, and stops pull out.

Caveat: Don't plunge, as the endmill will push the other way.;)
 
had spade drill the tip insert screws would come loose, fall out and even screw heads break off randomly.
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i just backed the feed off a bit til it stopped happening. sometimes you are just doing too much with a end mill.
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collet holders rarely hold as strong as set screw holders. i often use drill bits with weldon flat and hold by set screw. they obviously cant move much limited by the flat and set screw
 
Tool pull out in high speed machining happens all the time especially running End Mills 1/2" Diameter and up. We've done a lot of testing on this and here are the best holders we found:
-A Side lock End Mill Holder will not pull out and is the most economical option but they are not ideal for tool life as the set screw will naturally induce runout
-A Hydraulic Holder is ideal for smaller diameter tools (3/8" and under but it has to be on size, no collets) but tools will pull out at 1/2" Diameter and up in high speed machining especially with hi helix angle end mills because the holding power is not as strong as a End Mill Holder or a Milling Chuck.
-A Milling Chuck with Ball Bearings (not needle bearing chucks) or the HPI Bearingless Chuck linked above worked the best in high speed machining with a hi helix angle in 1/2", 5/8" and 3/4" Diameters as long as you aren't using collets (they need to be on size). HPI offers a Hardened Dowel Pin to prevent pullout on their bearingless chuck but this is only needed in 5/8" or 3/4" Diameter Tools with a hi helix (45 or 50 degrees). I can send more info to you on these if you like.

Hopefully this helps.

Mike
 








 
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