Why do I need collets for my mill? Isn't a chuck a lot easier and faster?

CODEMAN

CODEMAN

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You remember seeing the "lathe vs mill" as first purchase thread. Well I got the lathe first and you were all right….got the mill soon after. I got a HF mini mill which I'm having a lot of fun learning as much as possible.

My buddy, who's a machinist of sorts, says "save your money and don't bother getting collets for the mill. I've been using just a chuck since I got mine, and it's been fine."

So….why do I need collets? Maybe I should send them back to LM and get something more useful.

Steve
VT
 
The collets have a better clamping force and the biggest advantage is keeping the tool as close to the quill as possible. Room between the work and the quill can be decreased very quickly by using longer tooling/holding than necessary.

I have found that once you get to around 7/8" or so an end mill holder will work better for large cuts as the notch for the retaining screw is slightly more secure than a collet at that size. Just my personal experience though, others may disagree.

Mike.
 
The problem with using a chuck for milling is that the neither the chuck jaws nor the tapered JT## mount are suitable for side loads. Your friend might have been especially lucky, but the most likely failure mode is the chuck loosening from the taper when side milling, and falling off. Another potential failure mode would be the end mill pulling out of the chuck due to downward forces when side milling. Chucks are best at resisting upward pressure, because the end of the bit can bottom out in the chuck. For downward forces, you might have to make the chuck "farmer tight." That's not good for the chuck, either.

That said, if all you're using is 1/8" end mills, you might be sorta OK, at least for a while. But it sounds like you already have some collets ("Maybe I should send them back to LM..."). Even if not, collets aren't that expensive, and you really should get at least one or two to start with. Use them!

Best wishes!
 
When not if an endmill pulls out of that drill chuck and ruens your work pice and posibly the endmill you will know why collets are used. endmill holders for over 5/8 endmills. An endmill is to hard for a drill chuck to grip. also collits run much truer than a drillchuck.
 
I agree with what everyone has said so far. I'd like to add also, you're losing a lot of rigidity when the end mill us extended that far away from the quill.

As others have said, side milling has a downward force component that will pull the end mill or chuck down and out of the quill, which will ruin your quill taper and chuck in no time. Save yourself and your machine and use collets or an end mill holder, you'll regret it if you don't. Plus the machine will be capable of much heavier cuts.
 
All of the above, my friend. In summary -

Drill chucks are not good at gripping hard and smooth objects.

Drill chucks have too much runout for an end mill to be used effectively, accurately, or safely for anything besides drilling - period. The runout itself will cause problems for the end mill.

The short taper holding a chuck and arbor together - which should not be assembled with a great deal of force anyway - is not made to take a side-load, and you run the risk of it coming apart. This could possibly damage the machine's spindle.

If it's the speed of a tool change you're concerned about - don't. This is a hobby. Slow down, take the time to do it the right way. You can change a collet out in about 15 seconds - or, you can use a chuck and run the risk of damaging your machine and certainly break an end mill and drill chuck.

The only time I have ever used a drill chuck to mill is with a fairly large chuck and a fairly small end mill, taking very light cuts. Even then, I was sweating and white-knuckled. I shouldn't have even done that, in truth. If a length extension is needed - as in my case at the time - a solid end mill holder should be used.

Your "machinist of sorts" friend will learn his lesson one day.
 
Geez…I'm so glad I asked! I got a full set of collets from LM so I'll start using them immediately for all of my milling activities. :bitingnails:

I just got back from the auto parts store with some Permatex valve grinding medium, so I'm going to take everything apart and smooth down the gibs and ways of my lathe and mill.

Steve
 
Um, before you do that, I'd stop and see what others have to say. I was warned off using any sort of abrasive compound on cast iron as the grit stays in the city and keeps grinding away over time. Not a big deal on the bronze Gibs perhaps but I wouldn't use it on the dovetails
 
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