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Silverback
01-09-2009, 12:21 AM
Do you (maybe the right question should be should you) use endmill holders to hold end mills or are collets sufficient? I've run across a couple of recommendations suggesting that endmills cannot be held well in a collet, and should be only used with a set screw type end mill holder. OTOH, I haven't seen many people using them, it seems like you always see and endmill just stuck in a collet.

Honestly, I'm not all that experienced a machinist, but I've never had an endmill move in a collet, at least not that I noticed.

Teenage_Machinist
01-09-2009, 12:28 AM
End mill holders do not allow slipping which can be good or bad.

End mill holders need the flats on shanks.

Also they protrude more than collets.

I use holders with no problem.

Ken_Shea
01-09-2009, 12:56 AM
End mill holders need the flats on shanks.

Not necessarily disagreeing, however, not required for normal cutting, if you will be hogging then that would be highly recommended.
Before it is over you will have both collet and EM holders. Collet's grip more concentric (that is to say, a good collet and holder) and a set covers a lot of sizes that would require a one for each if using a tool holder.

Ken

EDIT:
Should say that while Collets can run more concentric, for the HSM on average equipment and for the average job it is almost irrelevant.

barts
01-09-2009, 01:41 AM
I used to use nothing but collets, 'cause that was all I had... then I turned a perfectly good not yet finished part into scrap because the endmill started climbing into the work while I was hogging... now I have one or two end mill holders for my bigger end mills...

- Bart

Mark Hockett
01-09-2009, 01:58 AM
I have both collets and end mill holders. I find I use the end mill holders more just because I have a rack full of them sitting there with end mills already loaded and ready to go. I just grab the one I need and pop it in the mill. It is just quicker for me and since customers are relying on me to be quick that is what works in my shop. I don't have a problem with either collets or holders and would recommend collets to someone just starting out if you have to choose between one or the other. Most beginners are not going to be hogging material so a slipping end mill will never be a problem.

Silverback
01-09-2009, 02:08 AM
End mill holders do not allow slipping which can be good or bad.

I could see good, but I'm not sure about why it would be bad.

All of you seem to agree that endmill holders are needed for hogging, at what point does cutting become hogging?

lazlo
01-09-2009, 02:10 AM
I could see good, but I'm not sure about why it would be bad.

An old machinist told me that's why they're called "Weldon" holders, because when the endmill jams, it Welds On to the set screw ;)

oldtiffie
01-09-2009, 02:30 AM
Oh dear me.

Any wood-worker who has ever used a router will give you a good answer for this.

Put the end-mill etc. "hard into" the collet so that it "bottoms out" then withdraw it about 1/8" (or more - suit yourself) THEN close/clamp the collet. A lot of problems are caused by the end mill shank being clamped by the collet and "hits bottom" before the collet is fully "home" such that when you think the collet is "clamped" it is not fully so due to the interference of the withdrawal of the collet into its socket.

This is mainly - but not only - a concern with collets in a collet adaptor in a mill spindle.

A lot of the problem is not "hogging" either but is due to "heavy handedness" with a less than adequately sharp cutter - especially so with compounding it by trying to "hog" and push the machine and the cutter too hard.

The problem gets worse with the "steeper" angled helixes on some of the "high performance" cutters.

I hear a lot about cutters cutting but little about using blunt cutters or sharpening them - particularly up the length of the spiral edges. The cutters don't stay sharp for ever.

Dull cutters and dull(er??) "machinists" seem to go together.

If I ever made the mistake of letting a "hogger and flogger" use or abuse my machines or tools he'd be out that door pronto - and made known in no uncertain terms that he's not welcome.

Driving a machine within its limits and without "belting it" is OK if and when NECESSARY - which is very rarely here.

I have yet to have a need for an end mill holder as I find that my ER collets do a good job.

barts
01-09-2009, 02:34 AM
I could see good, but I'm not sure about why it would be bad.

All of you seem to agree that endmill holders are needed for hogging, at what point does cutting become hogging?

For me it's a function of vibration - the endmills tend to walk if the load generates much of that.... there's no way I'd trust a collet to hold a 3/4" end mill if I push it much at all... I usually cut pretty slowly on cast iron or steel, but Al brings out the speed demon, and that's when I run into trouble ;)

- Bart

lazlo
01-09-2009, 02:37 AM
For me it's a function of vibration - the endmills tend to walk if the load generates much of that.... there's no way I'd trust a collet to hold a 3/4" end mill if I push it much at all...

Bart +1: I use collets (a mixture of R8 and ER40) up to 3/4", mostly for the convenience. But if I'm running a 3/4" corncob, I'll go for the endmill holder.

ER40 goes well above 3/4", but I've never tried to run a rougher in it.

oldtiffie
01-09-2009, 02:59 AM
I run a 20mm (~0.800") "roughing" (aka "corn-cob") cutter easily in an ER-32 collet. If it is being "pounded" and you can see or feel it, then its not just the cutter or the job that's getting thrashed - so is just about everything.

If you get all glassy-eyed and start to hyper-ventilate, dribble and drool etc. in those self-made situations, perhaps you are beyond help.

macona
01-09-2009, 03:48 AM
Depends on the collet type. I wont trust a R8 for much of anything. But I have never, ever had a ER collet slip. And if you are still paranoid there are ER collets that have a protrusion to grab into the weldon groove.

barts
01-09-2009, 03:54 AM
I was talking about R8 - the standard Bridgeport collet. I don't have a ER collet setup.

- Bart

Circlip
01-09-2009, 08:49 AM
Whew, at least everyone on here seems to acknowledge that a milling cutter should be retained in a collet AT LEAST. The number of posts on other forums that show cutters held in drill chucks with the safety rider "But it's only" are unbelievable. The cutter holders in my toy workshop are mini-Autolock types for screwed shank cutters, but a couple of adaptors I made for 1/4" and 6mm plain shank cutters (Yes, one for each) have allen grubscrews locating on to flats on the shanks. Takes a BIT longer to work safely but WTH, in HSM we don't have to cleave at the speed of light, or do we??

Regards Ian.

Just Bob Again
01-09-2009, 10:05 AM
On an older machine or a cheap machine, things are rarely perfect. The extra length of an EM holder on a machine with a less-than-perfect spindle often makes the difference between a lousy finish and an acceptable finish. If the holder does not hold the cutter nicely concentric, it will cut more like a single-point tool than a mill. The more expensive EM holders are ground offset by 5 tenths or a thousandth to keep the cutter centered when locked. The cheap imports are not ground that way. A 3/4 EM holder sticks out a good 2 1/2 inches. That is a much bigger concern for me than the possibility of a collet slipping. If it's a good collet, it won't slip. On a bigger spindle, like 40 or 50 taper, that's a different animal. But on an R8 or MT usually found in a small shop, I go with collets.

ERBenoit
01-09-2009, 10:47 AM
End mill holders need the flats on shanks.

I haven't knowingly seen everything there is to see. I have yet to see a flat on any shank less than 3/8" diameter.

Otherwise I use collets (R-8) and endmill holders (NMTB 30 / 40) equally and have no problems with either. The only time I've ever "slipped" a mill in an R-8 collet was my own fault. Loose drawbar.

loose nut
01-09-2009, 11:05 AM
The only time I've ever "slipped" a mill in an R-8 collet was my own fault. Loose drawbar.


Same here, all I ever use in my home shop is R8 collets and it's usually my fault if there is a screwup with them. Two big advantages with R8's is that they minimize the amount that is sticking out of the spindle, important on smaller machines found in home shops and they are cheaper than holders or ER collets.

Every type of holding system has it pluses and minuses.

PaulT
01-09-2009, 12:09 PM
High RPM, high feed rates or carbide endmills are asking for trouble in R8 collets. They work fine for lighter cuts though.

I've even had trouble with carbide endmills slipping in ER32 collets, solved by cleaning the shank and collet with laquer thinner and then tightening them up to 60 to 80 ft-lbs or so.

Some incorrectly assume that endmill holders will cause more runout because of the set screw pushing the endmill to one side, but the good ones are actually offset ground to compensate for this, I like the ETM brand, often on sale at use-enco.com. I would imagine the low buck chinese ones probably aren't offset ground.

For R8-ER32 collet chucks I like the ones from www.maritool.com, he has good deals on ER collets also, and he's a good guy that doesn't mind selling to the little guys.

Paul T.

A.K. Boomer
01-09-2009, 12:10 PM
Oh dear me.

Any wood-worker who has ever used a router will give you a good answer for this.

Put the end-mill etc. "hard into" the collet so that it "bottoms out" then withdraw it about 1/8" (or more - suit yourself) THEN close/clamp the collet. A lot of problems are caused by the end mill shank being clamped by the collet and "hits bottom" before the collet is fully "home" such that when you think the collet is "clamped" it is not fully so due to the interference of the withdrawal of the collet into its socket.

.


This post needed to be dragged back over to page 2, Tiffer takes his thinking a step further and is right on the money in his entire post but esp. The little tidbit of info above that I dont recall ever being mentioned on here, All the other factors have to be considered - the helix, the amount you plan on taking off, the rate, the dullness of the cutter itself --- Last but not least take a step back from your "power drawbar" and get a feel for your machine and know its limitations and you will never slip an endmill in an R8 collet unless your expecting way too much AND simply dont know how to use your machine, every single endmill I put in my machine is for a designated pre-assigned task -- its size,helix, sharpness and what I plan on using it for is then transfered into my bicep in the final cinchdown of my drawbar --- I cringe when I think about having some hillbilly system installed on my machine thats putting the identical leverage ratio on a 1/8" endmill as it does on a 3/4",,, save your freekin drawbar threads and spindle taper for when you need them -- on the bigger tooling - Remember -- this sites called HMS -- if your having problems slipping tooling in a collet then learn how to use your machine properly for what it was designed for, If you have a mill with 3 ponies and an R8 system then you need to learn your limitations, just because you have 3 or 4 horse doesnt mean you can use it to pull tree stumps out of your neighbor's yard --- yes power outgrew the original system for what it was designed for -- deal with it, All that means is power is no longer the limiting factor --- All one has to do Is look at themselves in the mirror and say "im not going to be a hillbilly today" otherwise take your pick -- get an underpowered machine and make your motor windings glow a nice orange/red or get lots of power and make the color happen at your spindle area, and dont forget to piss and whine and blame others that you dont have the common sense on how to use your machine... I can also bypass the rev limiter on my 92 tercel and blow the engine up in my driveway ---- whaaaaaa....
If your running production with lots of power then dont mess around and go with ER as they still hold the tooling uniformly, The only time Iv ever had trouble with the R8 is Like what ERB just stated as Iv found out it to be my own fault,
To me its superior to having a slop fit weld-on (in precision terms it is sloppy if you can slide it in and out of a holder I.E. it means that there is a measurable clearance) that you install and then "push" the tool over to one side, Not only is the cutter guarantee'd to be running slightly eccentric (I guess its subject to how much you tighten the set screw - real nice) --- its shaft loads are all distorted and this sets up funky patterns --- Last time I brought this up some "more experienced" member then argued that the "air cushion" on the screw side between the endmill and the holder was sufficient enough to take care of any cutting "deviation" ...
Yeah -- thats what I want to rely on to hold my endmill from flopping around in its most critical area before it leaves its holder (remember the set screw is half way up) some good firm air...:rolleyes: Junk

Silverback
01-09-2009, 12:45 PM
I'm not 100% sure that I get the router analogy... It's not a question of holding the bit, but the reason you don't seat a router bit all the way into the router's collet is so that you can get it out (push it in if it gets stuck and it pops loose). Come to think of it, the only time I've ever had an issue with a collet coming loose is with my big, 3.5hp router with a 1/2-1/4" bushing stuck in a collet and a 1/4" shaft bit in it, and even then it was my fault, I didn't tighten it down right because I was thinking about how annoyed I was at having to put that whole assembly together to make one really quick cut.

I would think that even with as much as some of you complain about R8 collets, the R8 + Drawbar setup on my bridgeport should hold better then the crush sleeve collet setup on the router, and I trust that up to 1/2" (I've done some really, well lets call it interesting, stuff with a router). My collets only go up to 3/4", and only have a few items that have larger then an 1/2" straight shaft (a set of flycutters with 3/4" shafts is probably the worst, otherwise I have a few 5/8" and 3/4" endmills that I don't believe I've ever used, it seems that I mostly use smaller end mills or fly cutters/face/shell mills, and a 3/8" chuck that came with the mill with a 5/8" straight shaft on it that I keep meaning to remove and put a proper R8 on and haven't yet).

I keep seeing 1" R8 collets that really make me wonder, I don't see how they really have enough metal to hold most things that come with a 1" straight shaft. I wonder if they would have any chance of holding something like the occasional 6-8" flycutter that you see with a straight shaft that size.

I've been trying to keep anything larger and or heavier or that I might put a heavier load on with an R8 shank so I don't have to think about it.

A.K. Boomer
01-09-2009, 01:23 PM
Maybe the problem is in the way we look at horsepower and how to utilize it?

Many complain that the newer BP and clone milling machines have outgrown their tool holding capabilities due to an increase in horsepower but for the most part I think in some instances it really comes down to the fact that "most" people dont know how to equate the extra ponies into extra work, they go about it the way they ran a lesser powered machine and dont take advantage of the extra RPM's or the extra RPM's that you can effectively run them at that the more powerful machines generally have, this means that in some instances a 3hp mill can do twice the work that a 1 1/2hp mill can do --- and here's the bonus --- IT CAN DO IT WITHOUT ANY ADDITIONAL TORQUE LOAD ON THE SPINDLE AND TOOL HOLDER.

H.P's are the sum total of two things - torque and RPM's --- this is not only true for "creating" them -- its also part of the policy one needs to adopt when they go to use them up ---- if you want to stay within certain parameters torque wise (the thing that causes tool slippage) to get a certain job done but yet want the job done sooner then bump the rpm's up and increase the feed,
In many instances the bigger HP machine can actually give you an option of creating LESS of a chance for tool slippage all while achieving far more material removal.

I can't tell you how many times Iv driven a car into my shop that was deemed inop. by the customer due to them totally cooking the clutch to were the car would not barely move anymore, I show up - hop in and drive it home while I let them drive my steed -- they follow and when we get to my shop they say --- How in the hell did you get it going let alone make it up pump hill - I say very carefully at first and then worked my way up to 6,500 rpm's in first gear:D (its ok -- its a honda):p

A.K. Boomer
01-09-2009, 01:32 PM
I'm not 100% sure that I get the router analogy... It's not a question of holding the bit, but the reason you don't seat a router bit all the way into the router's collet is so that you can get it out (push it in if it gets stuck and it pops loose). Come to think of it, the only time I've ever had an issue with a collet coming loose is with my big, 3.5hp router with a 1/2-1/4" bushing stuck in a collet and a 1/4" shaft bit in it, and even then it was my fault, I didn't tighten it down right because I was thinking about how annoyed I was at having to put that whole assembly together to make one really quick cut.

I would think that even with as much as some of you complain about R8 collets, the R8 + Drawbar setup on my bridgeport should hold better then the crush sleeve collet setup on the router, and I trust that up to 1/2" (I've done some really, well lets call it interesting, stuff with a router). My collets only go up to 3/4", and only have a few items that have larger then an 1/2" straight shaft (a set of flycutters with 3/4" shafts is probably the worst, otherwise I have a few 5/8" and 3/4" endmills that I don't believe I've ever used, it seems that I mostly use smaller end mills or fly cutters/face/shell mills, and a 3/8" chuck that came with the mill with a 5/8" straight shaft on it that I keep meaning to remove and put a proper R8 on and haven't yet).

I keep seeing 1" R8 collets that really make me wonder, I don't see how they really have enough metal to hold most things that come with a 1" straight shaft. I wonder if they would have any chance of holding something like the occasional 6-8" flycutter that you see with a straight shaft that size.

I've been trying to keep anything larger and or heavier or that I might put a heavier load on with an R8 shank so I don't have to think about it.


Your right SB 1" is a joke on R8 as is 7/8"

Tiffers description is taking about how a tool gets "sucked up" into the tool holder (upon tightening), If you jam your tooling all the way into the holder till it bottoms then some of the force that should be applied to holding your tool tight is now "gridlocked" into trying to hold it into the bottom out, This could be huge, You notice it on chucker lathe work esp. -- and although thats a 5C taper the principle is the same (the 5C is immune from the drawbar thread due to it having its threads on the outside, still, it can happen with a Installed stop and oversize material or collets that are tapered while unsprung i.e. bigger diameter on the tool end) -- it can draw a piece of stock in an easy.015" as it tightens, while most of this is just the collet slipping into its taper bore there is still concern with an R8 system that the drawbar thread can be protruding and if this is what your using as a stop it can raise holy hell -- If you try to stop it this way then some of your tension goes to another purpose other than "clamping the tool", not only that, you now create forces on your collet in which it wasnt designed for.

lazlo
01-09-2009, 02:27 PM
Many complain that the newer BP and clone milling machines have outgrown their tool holding capabilities due to an increase in horsepower but for the most part I think in some instances it really comes down to the fact that "most" people dont know how to equate the extra ponies into extra work,

I agree partially AK -- the R8 taper is not the limiting factor on a 1 1/2 or 2 HP machine. Or put another way, NT30 is overkill for a 2 HP machine, IMHO, and on most asian machines, they're not really 2 HP motors anyway, that the peak (stall) current. The actual operating power with a standard .8 service factor is ~ 30 - 50% less than that: 1 - 1 1/2 HP.

Add to that the fact that the varispeed mechanism itself loses another 30% of the power (as compared to the belt drive), and you're back to 1 HP of the original Bridgeport belt-driven J-Heads.


they go about it the way they ran a lesser powered machine and dont take advantage of the extra RPM's or the extra RPM's that you can effectively run them at that the more powerful machines generally have, this means that in some instances a 3hp mill can do twice the work that a 1 1/2hp mill can do --- and here's the bonus --- IT CAN DO IT WITHOUT ANY ADDITIONAL TORQUE LOAD ON THE SPINDLE AND TOOL HOLDER.

I don't follow the Honda over-reving analogy AK. There's an optimal speed and feed for any material. You seem to be implying that if you have more horsepower, you can increase the RPM's, and keep the torque constant. But if you increase the RPM, you have to increase the feed to keep the tooth load the same (or you'll flat-out destroy the cutter), so you're limited by the rigidity of the machine, and not the motor horsepower.

Davek0974
01-09-2009, 02:56 PM
I use (nearly exclusively) a Clarkson end mill holder and threaded shank tools.

I like the 100% positive grip on the tool and i can change tools pretty easily too. I keep my favourites screwed into the clamp and just swap clamps when needed.

I dont like endmill holders but do own an ER32 collet set as well as R8 collets.


Dave

A.K. Boomer
01-09-2009, 03:43 PM
I don't follow the Honda over-reving analogy AK. There's an optimal speed and feed for any material. You seem to be implying that if you have more horsepower, you can increase the RPM's, and keep the torque constant. But if you increase the RPM, you have to increase the feed to keep the tooth load the same (or you'll flat-out destroy the cutter), so you're limited by the rigidity of the machine, and not the motor horsepower.



It's why did state "in some instances" but yes I agree.

Im just sticking up for the R8 because I think its all I'll ever need for what I do, in fact I really like it and get tired of all the badgering about it --- I mean, if the other alternative is more like something that used the drive the rear wheels of my Dads mcormick farm-all C model then give me the R8.

This edit is also some extra food for thought for Silverbacks original question and some added bennies that the R8 system incorporates into its design, They are less apt. to break an endmill in the event of excessive sideloads due to more uniform pressure of the endmill holder --- while some will argue and endmill never breaks on the shank they need to re-examine there thinking as it doesnt take the shank breaking itself to prove this, the endmill will severe at the flutes root opposite of the set screw side, its the inherent "weak link" thats built into every weldon.
The R8 totally takes away the worries of different sized endmills as there can be variances esp. between carbide and some HSS-- the R8 system self adapts.
They are by far more versatile and can also be utilized for material holding instead of just tool holding, this in turn gives your mill "some" lathe like qualities and opens up entirely different opportunities for the low budget HSM'er... The weld-on holders can not achieve this due to a plethora of problems, -- one is that basic sized material is not an "exact science" and varies considerably -- even with some so called precision ground stock, the R8 dont care, like I say it self adapts --- in fact +or - .003" is not a problem in some cases much more... Even if you do achieve the correct size material you cannot effectively use it due to the limited length that you get to stick into the holder and also the dreaded set screw that you need to anchor with and not only destroy the material with but use it to self mutilate therefore make it difficult to retrieve from the archaic tool holding apparatus... Then there is the soft material factor and how you can not effectively rely on the high unit pressures of something like a set screw -- it will deform the material past its limits - the material will then achieve "freedom" from its designated holding fixture and in turn this will give it "freedom" to slap the fool thats using it right in the middle of his or her forehead...
last but not least, Yes the R8 system has no "interference locking system" That doesnt bother me one bit (no pun intended) due to the fact that its two inclined plane systems working together -- imagine a set screw thats pulling against a taper, I dont need no freeking interference fit!!!
(this message paid for by the coalition US and foreign R8 tooling manufacturing committee for profit and pilfering - have a nice day)