Thread: Milling in the lathe

I use an ER40 collet chuck with an MT4 morse taper in my Hercus 260 headstock. I made a draw bar from some all-thread with a nut welded to the end and a sleeve that fits snugly in the headstock spindle bore. I've never had a milling cutter slip that I'm aware of.

Before I got a mill I used to just grip the cutters in the three jaw chuck, though I've also used cutters in the tail stock as drills when I've not had a drill of the right size.

I'd be inclined to go for the collet chuck, possibly ER40, that way the collet chuck could also be used for holding stock for machining as well.
I use an ER25 in my lathe and mill, and not had a cutter slip.
Kryn

I have ER32 collets and a home made milling attachment for the Hercus that uses a second compound slide that handles vertical movement.
see https://www.woodworkforums.com/f189/home-milling-attachment-152165

I made it more as an exercise and haven't used it much as I have access to mills at work.

Dale,

I have a couple of Clarkson Autolock 3 Morse arbored chucks, one small and an intermediate. They hold cutters with little risk of pull out but unlike ER collets, they don't hold work. I have used them for lathe milling when the workpiece is too large for either mill and it's shape is such that I can adequately secure it to the cross slide. And I always use a draw bar.

Bob.

Collet chuck is the way to go i reckon, you can make yourself one pretty easily too, John "Doubleboost" on youtube has a series of video's on making one. Then you just need to buy a nut.

I simply stick mine in the chuck, don't understand why you world need a collet, a bit of enlightenment please???

Well I guess the 3-jaw is designed to hold a workpiece and cutters are meant to be held in a dedicated holder of some sort. That said, I don't see why you couldn't use the 3-jaw if it doesn't slip.

I prefer working with the ER40 holder over a 3 or 4-jaw. It's nice to not have that big lump of metal spinning at the higher speeds associated with end mills. Improves visibility too.

Originally Posted by sacc51

I simply stick mine in the chuck, don't understand why you world need a collet, a bit of enlightenment please???

Good question. The only thing I can think of is runout unless you have one of those real expensive adjustable 3 jaw chucks.
If you need an accurate slot and the slot drill is sweeping in a slightly bigger arc the slot will also be a bit bigger.
Other than that...

Phil

Speaking from personal experience the main reason for using a specialized holder for end mills and slot drills is to prevent the cutter walking out of the jaws. It's mainly an issue with spiral flute cutters because the right handed helix pulls the cutter towards the stock which is naturally away from and out of the jaws. Now it may work OK in a new three jaw chuck but if yours is worn or bell-mouthed like many are then you may see this happen. Left handed helix is a different story because it pushes the cutter back into the jaws.

Four Jaw chucks are better at holding the cutters, more force can be applied and there's the benefit of adjusting to run true so that the cutters will cut on all flutes.

I find the best solution is the Autoloc/posiloc type holders since the screwed shank on the cutter has a positive tendency to tighten into the chuck and against the tapered stop pin, as cutting forces are applied but you need to use screwed shank cutters!

The non-locking type collet chucks (ER,R8,MTx etc) can apply much more force then a three jaw but not always fool proof. The next best thing is the plain shank cutters with the flat for a set screw, this is to prevent rotation of the cutter and provide some locking against lateral movement of the cutter in the chuck.

I use a Posiloc in my Bridgeport mill whenever possible although the shank is limited to 5/8" or 16mm. I then use the R8 collets directly in the spindle taper to hold larger shank cutters with a lot of sweat on the brow


Peter.

Bob have you got a photo of your clarkson drawbar please.

Ewan, I'll have a look at the home made chuck.


As for why not use a 3 jaw. As phil said run out but also I get a none level surface as the mill tends to pull it self forward as it cuts, So effectively the further it cuts the deeper it cuts.
Maybe a newer chuck would hold better. I don't tend to have these issues with turning, which maybe due to the direction of forces and softer stock than the cutters so the jaws grip better.

Dale,

I agree with Peter regarding a lathe chuck allowing the cutter to move. I wouldn't trust my chucks.

Although I also have both an intermediate and a small 30 taper arbored Autolock chuck for use on the 13, I mostly use a Rego Fix and a Schaublin ER chuck because they consume less Z. Less also than their Chinese counterparts.

I've never had a cutter move but if I thought there was the remotest possibility and if that possibility meant ruin, I'd use the Autolocks.

As far as the drawbar goes, I think they are the ones I used in the Hercus No.O's horizontal spindle. I will have a look tonight.

Bob.

Yep Peter post a much more eloquent explanation of what I have experienced whilst I was typing my last post.

That would be appreciated Bob.

I think when I'm a bit more proficient I will try and make one like in the link Ewan posted.

In the mean time I might make a drawback for the Clark's which I hope is simpler project.

Originally Posted by sacc51

I simply stick mine in the chuck, don't understand why you world need a collet, a bit of enlightenment please???

Lrt's see what comes to mind.....

- most low cost 3-jaw chucks from China or India have enormeous runouts, anything from 0.2mm.... and even 0.8mm is not unheard of. Not a problem if you use a flycutter. But if you use an endmill, especially one of 10mm or less diameter, you have one lip only doing the bulk of the cutting. And if you use a slot drill, the slot will be oversize. And if your chuck does not hold the slot drill parallel to the center line, your slot will be a slight dovetail shape. Brand name ER collets have runouts less than 0.05mm, cheap noname ones have less than 0.1mm.

- 3-jaw chuck jaws are hardened. But the milling cutter shaft is hardened too, probably more so than the chuck jaws, especially if it was a carbide cutter. That is bad news for chuck jaw wear.

- 3-jaw chucks are heavy, thus have more inertia, leading to milling cutter breakage when things go wrong.It also takes longer for the spindle to coast to a halt.

- the gripping surface of a 3-jaw chuck is only about 10% of the gripping surface a collet has. This means to hold the milling cutter securely, you need apply a very high tightening force. That is bad news for the chuck scroll, particularly on cheaper chucks. The scroll wears prematurely and the chuck looses any accuracy it had.

- a 3-jaw chuck is more likely to cause accidents by inadvertently catching yaur hairs or sleeves. And when milling in the lathe with a vertical slide, visibility to the cut is very limited so you do indeed tend to hold your head close to the chuck to peek into the pocket you may be milling. The 3-jaw chuck is also more likely to spray coolant and chips around. And speaking of coolant/lubricant, if applied by a brush the chuck jaws may catch your brush, or your spary can if using WD40 on Aluminium.


All that said, using the 3-jaw chuck is much safer than using a drill chuck, and is an acceptable emergency method to clamp a milling cutter. The cutter is unlikely to work itself loose, particularly as milling in the lathe limits you to shallow finishing cuts because of a lathes very limited rigidity when used as a mill.