ok all you machining guru's

[biss03]

Something i struggle with all the time is trying to get a tool to spin "true" in a collet holder. typically i use a lyndex collet holder with a 3/4" diameter extension sticking out 3-4" in length. usually on the first try, i get it within .006-.007. eventually i usually get it within .001-.002 which is good enough for the diameters i'm cutting.

anyways, is there a secret way of tightening the collets to get them to grab equally? Some people around here say you have to slowly turn the tool as you tighten the nut.

 

any ideas would be appreciated!

[Marty A]

hello biss03

 

i'm not a big fan on lyndex holders. although we use them on two of our machines.

the cutter tends to pull out.the salesman says to to stop tightening them after three clicks. but you know how that goes. we also use tecnara holders they are little more expensive, but they are rally good holders that will spin pretty true. hope this helps.

 

marty

[robk]

We use Command tool holders and collets in here with TITAN solid carbide (4 flute length) end mills for certain applications. The runout for the tool can NOT exceed .0002, and it never does...No trick that I know of, just quality tooling.....Good luck.

[MACHINEMASTERG]

we also use command there great.... i think your problum lies in the 3/4 extention try and get a longer say 4"long collet holder verses clamping on the extention then the drill there could be some stack up error

[gcode]

You didn't mention whether you were using double

or single angle collets. The single angle are best.

The double angle collets are useless for milling and barely adequate for light drilling.

[chris m]

Unless I read that wrong, you said your tools run out 7 THOUSANDTHS?!?

 

Damn! That's pretty horrible.

 

What size tool is this?

 

My Lyndex ER20 and ER32 collet chucks regularly hold endmills and drills better than .0005"

 

There is no secret to this (we use "AA" or super precision collets), just make sure the tool is all the way up in the collet, don't overtighten, and tell the guys to stop putting those tools with Weldon flats in the collet chucks.

 

Wow

 

C

[Slick]

biss, We use Lyndex as well, and the only time I've really ever seen that much run out is on a drill. And that usually is a result of someone trying to force a certain size drill in the wrong size collet. But other than that I wouldn't think you'd ever come across anything more than 0.001 tops (which is still too much really).

Quick question for you though, are you checking the tool in the spindle of your machine? Have you checked to see if your spindle is spinning true? i.e. indicate in your spindle, check tool to holder, holder to spindle, tool to spindle. (I hope that makes sense)

[Tony]

Sometimes people dont clean out there collets after they use them. There are Chips in there.

When you tighten the collet the next time

(with the chips in there)

You bend one of the fingers.

That finger now has a memory and

is different from the others as far as

uniform tension goes.It is really apparent if you are cutting a runner where you keep hitting a deadend,that is where the weak finger will give and the cutter snaps off again and again.

 

To make along story short:

The collet is probally Damaged !

 

[ 06-05-2003, 01:18 PM: Message edited by: Tony ]

[biss03]

thanks for all the input everyone! you've all pretty much hit on all the things i thought of myself. when i indicate it in, it is setup in the spindle, so yes the spindle could be off but maintence would never admit to it even if they do see it off. the 3/4 extension is needed because of the tight clearance on the diameter and ordering special holders is like trying to pull impacted wisdom teeth in this economy. i've basically tried everything said in this thread and the best i could get was .002 at the end of the 9mm drill. the 3/4 extension itself has .001 runout so i guess i'm not doing to bad.

 

thanks again and keep the suggestions/stories coming!

[biss03]

[ 06-05-2003, 02:55 PM: Message edited by: biss03 ]

[Guest CNC Apps Guy 1]

First off when I put ANYTHING in a collet holder, I carefully inspect the holder. If there any burrs on the taper of the holder, I'll generally stone or scotch brite (finest grade available barely more abarsive than a T-Shirt) them off. Before I set up a machine, I clean the taper on the machine. If I feel "stuff" I'll spin it at like 25-50 RPM and wipe with a CLEAN rag. If I do that and still feel "stuff" I'll scotch brite it. It's always clean after that. I completely clean the collet, solvent and a tooth brush. Wipe off with a clean rag and run my hands over it. If I feel any burrs, I'll knock them off and wipe again. I then check the inside taper where the collet mates to and clean it out. I'll clean the threads where the nut screws on. For the nut, I check to make sure that the collar spins freely in both directions. If it does not, I order a new one. Lastly I check the tool. Make sure there are no burrs on it. Then I assemble everything.

 

We use ER Collets and I can generally get them to within a couple of tenths ( >.0003" ). If stuff gets crashed, check it, if it's bad replace it.

 

JM2C and HTH

[Rekd™]

quote:

---

We use ER Collets

---

We do too. TIR is generally under a few tenths. While you're inspecting, inspect the seats on the holder for cracks, also check the seat in the cap. It's easy to overtighten them, and they will crack if you do.

 

I love the opportunity to smack someone's forehead because they're using a 13" wrench with both hands to tighten a .0312 EM in an ER Collet!

 

'Rekd teh Stupidity that good takes teamwork

[Tony]

James

With that much attention to detail

towards clean tooling you could be a

......MolDMaker

There is only one guy here that Abuses

The tooling. So I diassemble the tooling and

put it into a pan of parts cleaner

That way he has to clean them off before

reassembling them

[MACHINEMASTERG]

we use brake cleaner works better then the safty clean solvent tank

[Guest CNC Apps Guy 1]

quote:

---

With that much attention to detail

towards clean tooling you could be a

......MolDMaker

---

I used to work in a shop where we had to hold True Position of .0003 - .0005 RFS on a regular basis. So ANY runout on my tools would eat tolerance like it's going out of style. It doesn't really take that much longer to set up. Maybe 5 minutes per tool if I take my time.

[Chris Rizzo]

Since were on collets now...

Another HUGE issue is using drills with a stamped size label!!! The stamped label is invariably upset a couple of thou, giving some nice runout right there. Might as well pack the collet full of chips, too. I'm always after my tool vendors when they send me drills with stamped markings, and frequently get the B.S. of how hard it is to get the printed labeled bits... Anyone have a favorite supplier of drills with PRINTED labels?

 

Sincerely,

Pissed in Portland

[iowajim62]

Hi cmr,

What's wrong with trying to stone,file,sand those pesky characters off the shank so it don't runout a mile ? j/k

 

On a serious note I prefer Guhring or Titex.

[robk]

quote:

---

On a serious note I prefer Guhring or Titex.

---

+1. Mitsubishi drills do great also...

[gcode]

I'll bet money that a close examination of the collet extension will show that the nose of itis cracked from being overtightened. It will be a hairline crack in the taper that is barely visible in a free state.

[iowajim62]

Another thing about collets worth mention.

 

I've seen collets cranked down so tight you can see the slot spacing is actually different from section to section on the collet. When you loosen(hammer) it up, the collet is now twisted.

 

One way I've seen collets tightened is to snug the tool up in the collet/holder, now tighten it and then loosen it back up and resnug it again and retighten it. And then actually looking at the spacing of the collet fingers.

JM2C

[gcode]

I think Command recommends an application

of oil (WD-40 or similar) to the collet, holder and nosepiece. You don't see many people do it, but it does help reduce the twisting mentioned in the previous post.

[Guest CNC Apps Guy 1]

quote:

---

I think Command recommends an application

of oil (WD-40 or similar) to the collet, holder and nosepiece.

---

Not a bad idea, not bad at all. I may have to try that next setup in the Mori or Haas. Our Cincis and all the holders that go into them are so far gone now. Only NEW holders go in the Moris or Haas, they have not been crashed yet, and the spindles tapers are still smooth as a baby's you know what.

 

[ 06-05-2003, 11:38 PM: Message edited by: James Meyette ]

[F. JAVIER]

" I love the opportunity to smack someone's forehead because they're using a 13" wrench with both hands to tighten a .0312 EM in an ER Collet!

"

 

At our tool crib we sawed off one end of the wrench to 4" length so we can minimize an overtight problem

[MetalMarvels]

The only problem that I have had with a Lyndex CAT40 ER16 collet holder was the one I created myself. The collet holders don't much care for being run into the side of an aluminum casting. After smoking it, the holder had a runout of about 8 thou........ I have run into the "drill" lettering problem with collets and have mostly gone to Guhring and similar drills that have laser-etched lettering. All of the other "stamped" drills I hold in one-piece integrated CAT40 drill chucks and save my collets for "smooth" shanked tools.

[CAM-mando]

Its sooo obvious, but I cant count how many times the problem was using the wrong size collet for the tool. Too large or Too Small.