More collet and milling tools confusion.

One thing i would add about E.R is that it is my favourite too, but you need to make sure your tools are using atleast two thirds the depth of the collet, this is what regofix themselves have said, or you risk damaging the collet. Ideally you should be making sure the tool goes through the entire depth to ensure even clamping pressure.

Michael W

Edited By Michael-w on 09/10/2018 19:16:48

I use ER collets for my work but a side face I was machineing found the cutter pulling out of the collet .Fortunately I had a sacrificial plate below the work so no damage.I chaged to my poilock chuck to finish the work.I admit I was taking a deep cut and this was probably the cause of cutter creeping down.

Frank

Most people under-estimate the force needed to secure an ER collet. Use a ball-bearing nut and pull on the spanners until you break a sweat!

Neil

Torqued rather higher than the average car wheel nut (for ER32), I believe? And usually supplied with a short spanner, if at all.

My point about the cost was that you don't need to spend around £50 on an ER chuck if you have a Morse taper lathe spindle. I have bought several MT3 collets very cheaply in clearance sales from various suppliers, presumably because there's not much demand for them, and have used them successfully. I also had good results from a fly cutter on MT3.

If money is no object by all means go for the best you can get, but there is a lot you can do with a little ingenuity and minimal equipment, as ably demonstrated in Neil's earlier post.

Mike.

It might seem like a benefit at first but i envy the MT3 size over having an MT4 spindle, which is so awkward because those size collets are either expensive or rare as hens teeth.

my only option is to make one myself if i'm able to which will be true to the lathe, but making it true to a nominal dia. might be a different trouble altogether!

These combined factors would make ER actually desirable for a large spindle bore in my opinion, plus i can swap them out to use on the mill.

Michael W

Edited By Michael-w on 19/10/2018 20:42:23

Just to give closure on my situation, I got an ER 25 collet chuck on a 100mm flange which fits right on the lathe flange. It was only £40 and I now have just one 6mm collet and 6mm end mill. I shall buy things as and when I 'need' them. One day I may even put work in a collet and there is a useful range on each collet.

PS those ER style collets are pretty damn clever with the interleaved cuts. They give you even pressure all along the contact with the tool. Worth buying even if just to sit and watch the way it works!!!

Why do't you just buy a MT4-MT3 sleeve, same applies to the other big bore lathes which tend to come with an adaptor . Think mine came from ARC

It's a good idea, i have got a 4 -2 step down, i think from arc too, and i tried one of those collet chucks to it and it still gave me poor runout,(0.15mm) i think they have a bit of a reputation for.

I have never tried actual spindle collets in them though, maybe they're a cut above the typical bunch. It could be my collets too they're not branded but came from RDG or ARC.

I take it you'd need a bloody coarse thread to tighten up an MT4 collet if it could exist? :P I used M16 to make a drawbar for an ER40 taper chuck.

This is really on the backburner but i was planning to ditch the taper idea altogether and go with a flange mounted chuck, in the vain hope i might get better result. 

Obviously the only way to guarantee a totally concentric part is to turn between centres but a collet chuck has it's useful moments for when you need to work on the opposite side of a part in two stage turning operations. 

Edited By Michael-w on 20/10/2018 15:37:25

FWIW:

My lathe has a 5MT mandrel, into which goes a MT5 -3 open end sleeve. Into that goes a 3MT ER25 or ER32 collet chuck, retained by a 3/8 BSW drawbar (The M12 thread in the collet chuck has been sleeved down to 3/8 BSW, if anyone wonders! Could have made up a M12 drawbar, but the same collet chucks also do duty in the Mill which has a very narrow bore in the quill.

Definitely a fan of ER collets, for many years. They can accommodate , in the larger sizes a 1mm size difference,(0.5mm in the smaller sizes < 4mm) so will take Metric or Imperial tooling.

Howard