Chuck slips off arbor!

[megafix4]

Hi all,

If you recognize the name at all, then you know that I'm really new to metal working.

I am using a recently purchased Grizzly Lathe/Mill combo. Recently I bought some slitting saws also from Grizzly, as well as an 'arbor' to hold saws of various diameters. I put the saw 'arbor' into my Jacobs chuck on my mill, and when I try to do amy slitting with even the smallest of the saws, the cotton picking chuck just pops off of it's arbor! I can tap it on, clean the arbor and inside the chuck with various non-oily solutions, and it happens again! This is true on mild steel as well as simple aluminum. I have yet to manage a 2 inch cut in the aluminum tonight. I go extra slow, fast. Same thing. I feed really slow, fast. Same-o. I cut very, very shallow or rather deep (.025 for deep). Same thing.

And to add insult to injury, I have end mills that when I try to just shave a little bit off the surface of a block of the above materials... shaving along the side, actually.. same thing happens with them!! Off pops the Jacobs chuck from its arbor and plop on the work bench.

Any ideas, other than getting a special arbor or something for the saws and end mills? The end mills are just 4 flute mills of various sizes, and it happens just as with the saws.

Thanks in advance for someone bailing an old timer .. in everyting except metal working. :-)


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Bruce Johnston

[Jim Hubbell]

I had the same problem! I figured out that chucks mounted with tapered fixtures will work loose if they are not loaded axially. I made an adapter for the face mill arbor to mount my slitting saws and no more troubles.For end-mills a regular adapter holds fine.

[snorman]

OK, this is not the purists answer, but try a little fine sandpaper on the mating parts. Easy does it! Clean them off, stick the arbor in and give it a good pop with a soft hammer.
It's magic.

[SGW]

Yep. A drill chuck is not designed to do what you're trying to do with it. You need to get some collets or end mill holders.

If you don't have them, get catalogs from MSC, Travers, etc. (www.mscdirect.com and www.travers.com). (http://www.travers.com).) Just reading through those is an education in tooling.

[megafix4]

Thanks, guys,

Right after posting the original question, I decided that this was just plain foolish! It seems as if in order to use every cotton picking tool I have, or am getting, I end up having to make some adapter or buy something else, to use the tool! (I was making an adapter to hold a DIFFERENT tool, when I ran into this problem... and THAT was being made, to hold a DIFFERENT cutting tool!)

Anyway, I decided to take the purely 'mechanical' way out, and I put a dab of loktite blue on the tip of the chuck and thumped it onto the arbor. Worked like a charm! If necessary, I can use ice on the arbor to separate the chuck in the future.

Thanks again for the input. This really, really is a continuous learning curve, and this group is a great place for new knowledge.

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Bruce Johnston

[martin_vanmeter]

A drill chuck is not the proper tool holder for anything other than a drill bit. Vertical pressure only. Any other cutting forces, like sideways, require an arbor with a threaded drawbar to snug the tapered arbor into the spindle and hold it there. Endmills should be used in a collet or endmill adaptor. Endmill adapters are available with threaded morse taper arbors.
Of course, I am making the assumption your spindle has a thru hole which will allow the use of a drawbar to hold the arbors in place.

[SGW]

Re: the adapter-to-use-the-tool-to-make-the-adapter problem:

I don't think the syndrome ever goes away entirely, but after a while one DOES get enough tooling so the frequency of the problem diminishes a lot. Hang in there!

[megafix4]

Thanks, SGw, for the encouragement.

Actually, I'm glad this problem popped up, because it helps clear up a bit about arobrs for me. There really isn't a lot said about them in the stuff that I've read before I got my lathe/mill.

Let's see if I have this straight: My mill takes an MT3 arbor, so if I want to properly use end mills, I need an arbor that adapts between MT3 and whatever the end mill arbor type is. Is that correct? And I assume a person must have one for every size of end mill he has, or else use some kind of spacer for each smaller one? It appears as if the end mill arbor must have a screw in its side to lock down on the flat spot of the end mill.

Futhermore, if my mill has provisions for it, I need the type of MT3 taper that has a threaded hole in the end, so that I can run a locking bolt down to the arbor to keep it in place?

Finally, the 'arbor' I bought for my slitting saws, has the same exact type of end on it as do my end mills. That is, straight, with a flat portion on it. Again, I assume this is for a lock screw.

And if my mill doesn't have provisions for coming doen through the shaft to the screw hole in the arbor, then I'm just .... out of luck???

Thanks again to all for being so patient and helpful with a real neophite to this stuff.



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Bruce Johnston

[martin_vanmeter]

You are on the right track magafix4.

Typically, you would need three endmill holders, 3/8" 1/2" and maybe 3/4", although for a 3in1, the 3/4" may be overkill. You can get most smaller endmills with a 3/8" shank or a 1/2" shank. The shank does not have to be the same size and the cutting endmill. The endmill holder will have the correct size hole for the endmill and a set screw to hold the "waldon" type endmills (ones with a flat spot ground onto the shank). This keeps the cutting endmill from "pulling" out of the holder....somehow the cutting action can create a downward force which attempts to pull the whole rig out of the spindle.

Thats where the threaded drawbar comes in. It threads into the back of the #3 morse taper shank and a simple washer and nut at the other end of the spindle will hold everything in place. It only needs to be snug....a great amount of force is not needed or wanted. Usually a light tap on the top end of the threaded rod with a leather mallet or brass hammer will unseat the endmill holder once the tightening nut is released to remove the mt #3 holder from the spindle.

"Real" mills have the drawbar regardless of the spindle taper - morse, R8, CAT 40, etc. Any taper type fitting needs something to hold it in place when the cutting forces are horizontal as opposed to pure vertical when drilling.

[SGW]

You should be able to use MT3 collets, which are threaded for a drawbar. I assume your milling spindle has a hole through it for a drawbar. You won't need that many collets for end mills: the shanks of most end mills are 3/16", 3/8", 1/2", 5/8", or 3/4". Get that set of collets and you'll be able to handle almost anything. Eventually you may want some more sizes, but wait until you need them.

Alternatively, you can get end mill holders with MT3 shanks. Those will have a setscrew to bear on the flat on the end mill shank, but collets are just as good. One advantage to the end mill holders is that they project down a bit below the end of the spindle, which is occasionally handy when getting into a tight space.

You can get a slitting saw arbor (if you don't have one) with a 1/2" shank, which will also go in the 1/2" collet.

If your mill spindle doesn't have a hole down through the middle of it for a drawbar I'd say you are indeed out of luck, but it almost certainly (he says) must have one. You can make up a workable if not elegant drawbar out of a piece of threaded rod the right size; just cut to length and braze a nut on the top. I *think* MT3 collets are threaded 1/2-13, but you should verify that.....

Get a copy of the MSC and/or Travers catalog and look at the mill tooling. It will be an education in itself, just to see what's available. (www.mscdirect.com and www.travers.com) (http://www.travers.com)) Usual disclaimers; I've dealt with both companies and found both of them reliable.

[mike thomas]

megafix4, Check out ebay for end mill holders. I use a Palmgen, also an ebay purchase, milling attachment on my lathe. I picked up morse taper Weldon made end mill holders new for an average price of about $5. Be careful about who you purchase from, do not get excited, realize another buy will come along, and bid late and you will do ok on ebay. JTS Machine was auctioning quite a few of the Weldon morse tapers and I found their service prompt and courteous. Mike

[smoking joe]

I had one of the 3 in 1 machines from Enco.I believe that they are the same machine.Enco does carry the MT3 endmill holders I purchased the 3/8 and 1/2 inch holders and they pretty much cover all you'll need.The machine does have a hole through the spindle.I made the drawbar from threaded rod with a nut.I didn,t have a way to braze so after measureing the right length I drilled though the nut and the rod and pressed a pin through.I believe it was threaded 3/8-16 but not sure.You will still need to take light cuts because you can,t get close to the table with these machines and the set up is not as rigid as it needs to be.Finaly got rid of the 3 in 1 and got a southbend and one of the Jet mill/drills.Every thing is alot easier now But at least the 3 in 1 got me started.

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[smoking joe]

I had one of the 3 in 1 machines from Enco.I believe that they are the same machine.Enco does carry the MT3 endmill holders I purchased the 3/8 and 1/2 inch holders and they pretty much cover all you'll need.The machine does have a hole through the spindle.I made the drawbar from threaded rod with a nut.I didn,t have a way to braze so after measureing the right length I drilled though the nut and the rod and pressed a pin through.I believe it was threaded 3/8-16 but not sure.You will still need to take light cuts because you can,t get close to the table with these machines and the set up is not as rigid as it needs to be.Finaly got rid of the 3 in 1 and got a southbend and one of the Jet mill/drills.Every thing is alot easier now But at least the 3 in 1 got me started.

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[smoking joe]

I had one of the 3 in 1 machines from Enco.I believe that they are the same machine.Enco does carry the MT3 endmill holders I purchased the 3/8 and 1/2 inch holders and they pretty much cover all you'll need.The machine does have a hole through the spindle.I made the drawbar from threaded rod with a nut.I didn,t have a way to braze so after measureing the right length I drilled though the nut and the rod and pressed a pin through.I believe it was threaded 3/8-16 but not sure.You will still need to take light cuts because you can,t get close to the table with these machines and the set up is not as rigid as it needs to be.Finaly got rid of the 3 in 1 and got a southbend and one of the Jet mill/drills.Every thing is alot easier now But at least the 3 in 1 got me started.

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[Thrud]

megafix4

Best thing for holding endmills (if threaded) is the "Osbourn Titanic Endmill Chuck" overpriced, but the endmills never squirm out.

I use a Schnaublin (Drawbar shank MT2) E25 chuck with Lyndex ER-25 1mm-16mm Ultra precision collets and a Lyndex ER-25 Ball Bearing nut. You will not believe how much better this holds endmills, drills, etc. I have my smaller keyless chucks mounted on 1/2" or 5/8" straight shanks for use with the "Wee" stuff. Once I clocked it in for highest accuracy, I have never removed it from the mill. All my tooling is adapted for this configuration.

Dave

[megafix4]

Hi all,

Just a final followup on this. Thanks to the education I got here, I managed to get the proper MT3 end mill holder from JTS, and what a difference! Not only do the end mills stay in place nicely now, but the mill runs MUCH quiter when I'm using the end mills. I'm going to pick up one more end mill for my sliting saw holder and I should be set for awhile. Once I knew what I was looking for, I even found that Grizzly sells the things, but as seems to happen with most of the stuff I've ordered in the past month or so, they're back ordered for about 8 weeks.
Thanks opnce again for the education about tapers. I really appreciate it. Now I'm going to see if I can find some place on the 'net that gives the specs for the various tapers for various arbors. I have it for the C5 and R8 collets, thanks to this group, and I just want to understand more about the 'what' and 'why' for there being so cotton picking many tapers!



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Bruce Johnston

[SGW]

I expct the "why" is buried in the depths of history. Back in the earlier days, the concept of interchangability among companies didn't exist. In fact, companies went out of their way to make their stuff unique, so you'd have to come back to them for parts. I suspect that's one of the reasons there are so many tapers. Morse developed their set of tapers; Brown & Sharpe developed their set of tapers; Jacobs developed their set of tapers; every lathe manufacturer had their own pet idea about collet dimensions.

Now, sometimes different tapers DO make sense. But a lot of it, I'm sure, came from a desire of companies in a newly-developing industry to do it OUR way. We still see this sort of thinking, to some degree, in the computer industry today. How many communication protocols do we have, for instance? Do we really need all of them? As the industry matures, standards become more acceptable.

One major differentiation among tapers is "self-holding" and "self-releasing." Morse tapers, for instance, are self-holding; knock one in, and it stays put until you knock it out again. The #30, #40, #50 tapers used in big milling machines are self-releasing; loosen the drawbar, and the thing falls out. The dividing point is a taper of around 15 degrees, give or take. R8 collets are ALMOST sefl-releasing, but not quite.

[Thrud]

SGW
Good point on the taper discussion...

Do not forget the 30 Taper and larger standard spindles also have positive driving lugs that engage the flange on the toolholder in addition to upwards of 25,000 Lbs on the drawbar (it ain't falling out for sure while running!)

Dave

[megafix4]

Thanks, SGW,

That makes sense. Even the business about all of the software protocols makes sense, and I agree with you on that, having been in the computer service industry for over 40 years.

If it's just a matter in many cases, of trying to trap the market, then at least it's good to know that's the only reason. In the case of someone new, like me, then it's hard to tell what's really important and what is just a game the manufacturers play.

Thanks to guys like you and others in this group, my learning curve is getting a bit flatter. My problem is, to add to the lack of knowledge that I have, I also have curiosity. THAT can put a few real slants into that learning curve!! :-)



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Bruce Johnston

[Thrud]

Bruce

Curiosity is a good thing, it is what drives man's meager knowledge of everything closer to the truth. Questions are what makes us look for and discover new knowledge.