Holding End Mill on small lathe

[Nigel McBurney 1Participant @nigelmcburney1]

nothing wrong with milling in the lathe,I did a lot of the milling on a 11/2 inch Allchin with a M7 and held the cutters in a 4 inch 3 jaw, admittedly the lathe was new (1968) ,never had a cutter move ,though I do not think it would be so succesful with an old chuck with wonky jaws. I cannot see the point of the suggestion to use a parallel shank ER collet chuck held in a three jaw,a parallel shank cutter is the same as a parellel chuck with the additional problem of it placing the cutter a lot further from the lathe spindle bearing, the use of a 1 mt collet would give the advantage of the cutter being very close to the end of the lathe spindle. As others have mentioned never use a Jacobs chuck to hold a milling cutter a mill with a sideways load, though its ok to hold a milling cutter in a jacobs chuck in the tailstock to make counterbores,ie an end on load. For milling in the lathe where a surface needs a flat face its cheaper to use a fly cutter, with HSS toolbit , easy to sharpen,and can be mounted in a block bolted to a face plate.

[oldveloParticipant @oldvelo]

Milling cutters in a lathe or drill chuck will hold much better if the shank of the cutter is inserted as far as possible.

Tighten the chuck using all the three holes plus once more in hole one.

NEVER use a cutter with the diameter of the flutes greater than the shank in a three jaw chuck.

As an old mentor of mine said "Tighten all four holes in a three jaw chuck and five holes in four jaw chuck".

[Rowan Sylvester-BradleyParticipant @rowansylvester-bradley37244]

Posted by pete hammond on 15/03/2020 08:57:42:

Just a thought – if it is only a very occasional or one off requirement then I, or an other enthusiast local to you, with a slightly better equipped shed/workshop could do the job or allow you to do the job (under supervision- we tend to be precious about our tools).

I'm Bucks based so if you are local – I'm offering.

That's a very generous offer, Pete. Bucks is not exactly next door, but easily drivable. However, I think I will have a go at making one of these parts myself, on the basis that one only learns by trying things. If I get into trouble, I may well want to talk to you again about taking up this offer.

Thanks – Rowan

[David George 1Participant @davidgeorge1]

Before I bought my milling machine I bought an mt1 ER16 collet set and did some usefull milling on the lathe. Indeed with the help of the vertical slide and a fly cutter machined some castings.

David

[BazyleParticipant @bazyle]

The picture above brings up one point – long distance of cutting edge from bearings. You would do better to simulate a small cutter by putting a cranked lathe tool in a 4-jaw chuck. Just think a bit about the cutting edge to work out the best orientation.
Then if you want a larger diameter flycutter make a little block that holds the tool on a faceplate. You could even get a spare chuck backplate drill a hole for a round toolbit near the edge and drill and tap a hole radially from the edge to clamp the tool.
The only need for an actual end mill, or rather slot drill would be for a very small one to cut steam ports or the like.

[Mick B1Participant @mickb1]

Here I'm skimming the valve face on a cylinder with a vanilla boring bar in the chuck carrying an HSS toolbit.

Pussycat cut, but next one was a lot deeper to reach drawing dimension. Obviously there are limitations compared to a solidly-built milling machine, especially on side-depth of milled steps, but I've found little I couldn't actually do with a bit of patience.

Flycutting valve face.

[FarmboyParticipant @farmboy]

Having done a limited amount of milling on my C4 lathe, using MT2 collets in the headstock, I am genuinely puzzled as to why anyone would deliberately introduce extra flexibility into an even more lightweight machine than mine by putting a secondary collet chuck in the morse taper, moving the cutting point further from the headstock bearings for a job where rigidity would seem to be one of the most important factors.

I have also achieved quite good results with a MT2 mounted fly-cutter. Again, the rigidity is better close to the bearing.

There must be a serious 'down side' to morse tapers that I haven't yet discovered if so many people dismiss them so easily . . .

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Farmboy on 16/03/2020 20:31:17:

[…]

There must be a serious 'down side' to morse tapers that I haven't yet discovered if so many people dismiss them so easily . . .

.

The main [and perhaps only] ‘down side’ is that Morse is a ‘self locking’ taper and therefore tools frequently need forcible extraction … Those with a sensitive disposition would prefer a steep taper which releases immediately the draw-bar is undone.

MichaelG.

[IanTParticipant @iant]

Extracting a Morse taper can be a pain (most especially if you have tweeked the drawbar a bit too hard) but there are solutons.

My (MT2) Clarkson collet chuck has a screwed body that simply pulls the taper out of the spindle. Most MT 'blank' arbors can also be extracted easily if you have an open threaded nose-piece fitted to the lathe mandrel and make a 'U' shaped plate to fit over the back end of the MT arbor. Unscrew the threaded nose and it pushes against the U-plate and pulls the taper out.

If you drill the arbor for the milling cutter required (and drill & tap the body for a grub screw) you will have something that will hold the cutter pretty firmly and is easy to remove.

At least that's what I did before I got the Clarkson (and before ER collet chucks came from China for 2/6d including postage). Generally this works for other MT-based items too – slitting saws, fly-cutters, live centres etc.- but not of course for MT collets that are flush with the nose.

Regards,

IanT

[Paul LousickParticipant @paullousick59116]

Morse taper tools should not need to be over tightened, just enough to allow them to grip and not turn in the spindle. They should only need a slight tap to remove them. (I am always worried about damaging bearings if they are hit hard).

Drills with a morse taper shank, used in a mill or pedestal drill are removed by inserting a wedge, thru a slot in the side of the spindle, behind the tool. This method can also be used to remove a milling cutter if it is of the right length by first removing the drawbar.

If this cannot be done, a wedge can sometimes be used between the end of the spindle and the cutter holder. (details were published in MEW).

[not done it yetParticipant @notdoneityet]

MT3 arbor sleeves can be obtained with a screw extractor already to go (not much help for a mini).

I have made some wedges, used in pairs, to remove tools if they need more than a light tap with a soft metalled hammer (never use a steel hammer on the drawbar – unless your drawbar is brass&#128578.

Arc supply sets of wedges. Need care with drill chucks as they might come off instead of the MT breaking away. I’ve never had that problem and maybe the JT tapers are considerably tighter than Morse ones?

Paul’s set up looks easier from the point of view of easier control, but my pairs of wedges are pretty quick to use. Don’t fully remove the drawbar when using two wedges – you might need a third to catch the tool on ejection, or arrange something for a soft landing!

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