[kentdesautel13]

I have a bit of a mystery in the shop this morning... I had my 1/2 inch 4 flute end mill suddenly cutting about .20" to deep on a piece. (It actually cut about .07" down into my soft jaws )

This is an end mill that stays with this machine, so I know it's not from another machine.

So after checking all of the obvious I checked my length on my end mill and sure enough it had dropped down.

I've had end mills push up into my collet, but never down.

The puzzling thing is that when I took the end mill out the collet felt tight like it should.

So I'm thinking that maybe it heated up just enough to get loose in the collet and then drop down a bit and then stay at that position once it cooled?

Anyone ever run into something like this?

Thanks,

Kent

[metalmayhem]

likely the tool pulled out of the collet while cutting , they can push up or pull out . Best to use side lock for tools 1/2" and over , unless it's just a finish tool

[deadlykitten]

hy this happens mostly to endmills with helix flutes; during heavy cutting, apears a tendency ( somehow similar to a nut that is rotating on a screw ), that may shift your tool and/or your part

during heavy side milling, most endmils have a tendency to be pulled out of the collet, because most helixes are Z type; for the tool to be pushed in, requires a reversed helix, thus S type, but this are not common items; just like metalmayhem sugested, secure the endmill with a side screw if endmil's shank is stright, use a grinder to make kind of a flat, so to be sure that the tool won't be pulled out

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even more, on powerfull machines, during heavy facing with large tools with tilted insert seats, the stock may be raised from the vice, so it is recomanded for such high mrr operations, to use reversed tilted seats ( thus kind of chaninging the toolholder, from one that uses positive inserts, to another for negative ); i just remembered, another condition is that ae ( that one from ae & ap ), when ae<tool dia, must be centered with the tool axis, so to avoid high servo loop reaction for the axis that is not feeding / kindly

[mactec54]

I have a bit of a mystery in the shop this morning... I had my 1/2 inch 4 flute end mill suddenly cutting about .20" to deep on a piece. (It actually cut about .07" down into my soft jaws )

This is an end mill that stays with this machine, so I know it's not from another machine.

So after checking all of the obvious I checked my length on my end mill and sure enough it had dropped down.

I've had end mills push up into my collet, but never down.

The puzzling thing is that when I took the end mill out the collet felt tight like it should.

So I'm thinking that maybe it heated up just enough to get loose in the collet and then drop down a bit and then stay at that position once it cooled?

Anyone ever run into something like this?

Thanks,

Kent

This is normal if you have not torqued the Collet Nut to the correct Torque, what size is the ER Collet you are using

[CNCMAN172]

Deformed or worn collet, could have been cross threaded as well. Once they slip it often will happen again

[kentdesautel13]

Thank you everyone for your suggestions.

About the time that this popped up I was doing some heavy side milling, so that must have been when it happened.

But to be safe I will take the suggestions and change out my ER 32 collet and get a fresh new one installed to be safe.

Thanks again....

Kent

[mactec54]

Thank you everyone for your suggestions.

About the time that this popped up I was doing some heavy side milling, so that must have been when it happened.

But to be safe I will take the suggestions and change out my ER 32 collet and get a fresh new one installed to be safe.

Thanks again....

Kent

So, to use the ER32 you would need 90 to 110FT-LBS of torque to hold the Endmill, Collet must be clean and free of any lube, using a side-lock Tool Holder the cutter can still move a small amount on the Welden flat if not torqued correctly, this type of holder can't be used for high-speed machining as they don't have good balance

[metalmayhem]

Thank you everyone for your suggestions.

About the time that this popped up I was doing some heavy side milling, so that must have been when it happened.

But to be safe I will take the suggestions and change out my ER 32 collet and get a fresh new one installed to be safe.

Thanks again....

Kent

it's a good temporary solution but you'll always be vulnerable to these problems with er collets when doing heavy cuts . Er are designed to be precision holders vs heavy machining . If your preference is to use collets then tg would be a better choice , even though they can and will slip under heavy cutting situations . They are better for heavy cuts but still not ideal since there is nothing locking the cutter in place

[mactec54]

it's a good temporary solution but you'll always be vulnerable to these problems with er collets when doing heavy cuts . Er are designed to be precision holders vs heavy machining . If your preference is to use collets then tg would be a better choice , even though they can and will slip under heavy cutting situations . They are better for heavy cuts but still not ideal since there is nothing locking the cutter in place

TG collets don't have anywhere near the gripping power you can get from an ER Collet system, that is how and why the ER collet system came to be developed, it is the most sold / Collet system in the world, it was Patented by Rego-Fix in 1973

That being said TG did make some with a locking pin for the Welden shank cutters, which holds the cutters in place and there is no chance of any cutter having any pullout or push back, I have some I may take a photo tomorrow, ER should do the same on the larger Collets, most would have never seen these special Collets

[metalmayhem]

There are reasons that er are now the most common collets and thats largely due the flood from China . They were getting popular before that but it's been an explosion . They are versatile holders I'll give them that and most of my cutters are mounted in them , but every tool holder has it's place . Tg did make them to handle woodruffs but I don't know if they still do that
I've seen more guys have pullouts from er than tg by far , plus tg provide less chatter from my experience . Thats why tg is still popular in big heavy shops . Neither one is the best collet system though , they are just the most common and affordable . Regardless , collet holders and heavy cutting are words that don't belong together in my opinion

[mactec54]

There are reasons that er are now the most common collets and thats largely due the flood from China . They were getting popular before that but it's been an explosion . They are versatile holders I'll give them that and most of my cutters are mounted in them , but every tool holder has it's place . Tg did make them to handle woodruffs but I don't know if they still do that
I've seen more guys have pullouts from er than tg by far , plus tg provide less chatter from my experience . Thats why tg is still popular in big heavy shops . Neither one is the best collet system though , they are just the most common and affordable . Regardless , collet holders and heavy cutting are words that don't belong together in my opinion

Thats' why they have shrink-fit Tool holders and hydraulic Tool holders

You only get pullout with any collet Tool holder if is incorrectly installed / Torqued to the specs required, or it's being used incorrectly, that's also why they make Torque adapter wrenches for each Collet Nut type, this goes for any type of collet if you want reliability installation is key.

Your China analogy is total Bs, if you are a machinist or have any kind of machine shop, you would never buy a Chinese made Collet of any type

[deadlykitten]

I encountered pull out even from hydraulic toolholders, not light ones, but from the "most powerful" version, which was way bigger, and a known brand ... during roughing, collets are indeed useless

Collets that prevent the tool from being puled out sound as a fancy solution, but they end up rotating inside the chuck

[metalmayhem]

Thats' why they have shrink-fit Tool holders and hydraulic Tool holders

You only get pullout with any collet Tool holder if is incorrectly installed / Torqued to the specs required, or it's being used incorrectly, that's also why they make Torque adapter wrenches for each Collet Nut type, this goes for any type of collet if you want reliability installation is key.

Your China analogy is total Bs, if you are a machinist or have any kind of machine shop, you would never buy a Chinese made Collet of any type

You knock chinese right here and now but in a discussion not long ago you told me china makes just as good quality cutters as any of the big manufacturers . If they could accomplish that then er should be cakewalk
As I stated they were gaining popularity before china , but that has since exploded . I'm sure you can't find a tg collet made in china , they don't specialize they just copy what is popular . When I worked in the industry the most common used was lindex and techniks , nothing chinese . I run tormachs in my shop and the chinese collets are sufficient enough , otherwise I have tools in side lock or er on a torus . These machines aren't capable of hogging and precision is pretty limited , or I'd be using what I need to suit the situation

I bet 80-90% of the users on this forum use chinese er holders and of that 90 I'm sure most have never heard of or seen tg . Popularity comes from word of mouth and seeing what others are doing and not what is necessarily best . Then thrown in cheap cost , this is where china comes in

The problem with collets is the fact that , you have 2 hard smooth surfaces and the only thing preventing a tool from pull out is friction . You can never 100% lock anything in place based on friction , with enough force something is going to move . For anyone claiming to use er for any hogging or heavy machining and never had pull out then the truth of the matter is they probably are not using their cutters to their full potential .
Shrink fit and hydraulic are also not suited for hogging because once again friction . Both are expensive and are much better suited for high precision and high rpm's

There are numerous civil arguments regarding clamp force of er vs tg , look through the forums (not just cnczone) and the argument leans much further to tg than er