Collet choice?

[minerva]

Hi Guys
I'm looking for some basic advice re COLLETS.
I'm at the stage where the purchase of my first milling machine is seriously imminent! And it was only yesterday whilst browsing one of Bogs old posts re his workshop refurb. that I noticed how many collets of one sort or another featured in the various storage racks in the many pictures. Now, my lathe is of the far eastern mini variety with a 3 MT headstock taper. A dedicated ER32 collet chuck for bolting on in place of the 3 jaw is readily available from Arc-Euro here in the UK, also the same chuck with a 3MT arbor is available, both of these chucks do not appear to utilise the use of a draw-bar of any description? My question is, given that the milling machine spindle will almost certainly be 3MT would the purchase of a single 3MT ER32 chuck + selection of ER32 collets suffice for use on both machines or is there other factors relating to the draw bar/ cutter mounting which makes the use of other types of collet preferable? or indeed necessary. given that the number of types of collets offered is bewildering to say the least.
Thanks in anticipation ,
Terry

 

[Tin Falcon]

My question is, given that the milling machine spindle will almost certainly be 3MT would the purchase of a single 3MT ER32 chuck + selection of ER32 collets suffice for use on both machines or is there other factors relating to the draw bar/ cutter mounting which makes the use of other types of collect preferable? or indeed necessary. given that the number of types of collects offered is bewildering to say the least.
Thanks in anticipation ,

I have similar equipment . A grizzly 7x lathe and a x-2 mini mill. I purchased the ER-32 3mt for my mill intending to also use it on my lathe. It certainly can be used that way with a draw bar of a different length.
the problem i found with this system is it takes up way to much z axis space on the mill. 3 inches.this is ok for some things but others it is virtually impossible to fit a tool on if the part is a bit high or the tool is long. On the lathe not so much a problem because it is the same length as the stock chuck.I ended up buying 3 mt collects for the mill. these could also be used for the lathe.
If I was doing again I would get a mill with r-8 tooling and get 3c collet set up for the lathe. the 3c will allow you to put a long piece through the collet and through the headstock of the lathe . you can also set up internal stops for second operations. This would also free up some z axis space on the lathe.

Tin

 

[ksouers]

Terry,
Yes, I agree the collet choices available are quite bewildering. One can spend a bloody fortune on the things. I use 4 collet systems in my shop: MT3, 5C, R8 and recently added an ER40 system to my mill.

Usually the collet system you use is determined by the machine but as you've found there are adapters. The ER collet system, regardless of size, is a self-extracting pass-though collet. There is no draw bar to contend with. The 5C is also a pass-through collet but is not self-extracting and requires a draw tube to pull it up tight. A collet chuck is available for the 5C that solves the self-extraction and draw tube issues. The MT3 and R8 are blind collets and require a draw bar and are not self-extracting.

The ER adapters have a couple things to contend with. They introduce flex into the system and eat up a considerable amount of room. If possible, use a bolt-on type chuck. They take up no more room than a regular 3-jaw chuck and are much more rigid. The R8/ER40 chuck I use on the mill sticks out about 4 inches. That's 4 inches of room lost. On my knee mill that's usually not an issue, but if I put it on the X2 I would lose about 50% of my available table-to-spindle room!

If space is going to be an issue, as it usually is on most bench-top mills, I would stick with whatever collets the spindle was designed for. If your lathe and the mill are both MT3 then you only have to invest in one set of collets.

 

[Andrew_D]

I use MT3 collets in both my mini-lathe and mini-mill. The mill was advertised as R8, but when I got it home, I found out it was MT3. Saved buying another set!

The mill also came with an MT3->ER-32 chuck and an almost-complete set of 1/8"-3/4"x1/16" collets.

So far, they do everything I want. As others have said, on machines this small, the extra stick-out of the ER-32 chuck is a concern. Both for rigidity and space issues.

Actually, I use the MT3 collets more...I find them quicker to change. At first, I was tightening them down too hard. They don't take much pressure when tightening the draw-bar...only a little bit. If you are using more than one finger on the end of the wrench, you're probably over-tightening!!!!

Andrew

 

[Blogwitch]

Terry,

You shouldn't take my workshop as the norm, mine were obtained for a specific reason, and that was for turning it into a production invironment. I needed to hold materials any which way to get the job done in the shortest possible time.

I used to use ER32 all the time, but even with a fairly large throat on my mill, I found at times it was too intrusive and very awkward to use, and now mainly use the quill taper for holding, mine are R8 on the mill.

The ER still gets used, when I am trying to hold some obscure sized shanked cutter that managed to find it's way into my collection, or for holding non standard sizes on the lathe.

You can easily get confused about which one is best for you. Maybe in the long run, you may need to buy say ER and MT, or other combinations to satisfy your machine holding needs.


Bogs

Bogs

 

[minerva]

Thanks for the prompt response guys

Tin / Kevin
The R8 collets you both mention presumably require a machine spindle that is profiled to take same. I have found in the tooling catalogues R8 adapters but these merely converts R8 back to MT3 which already exists on the machines I have in mind.

Tin sorry to seem a bit thick *club* but does your comment mean that you DO use a draw bar with the ER32 in both the lathe and the mill? If so does the said chuck come with a threaded facility at the "narrow end" of the taper? (if that makes any sense?)
I take on board the comments about flex and space limitation and perhaps I should take another look at possible contenders for purchase given that most of the small mills seem to be MT3.

Andrew
Thank you for your timely comments ,you will be pleased to know the lights "came on" when a further look at the catalogue revealed surprise, surprise you can buy MT3 collets which presumeably negates most of the objections with regards to flex and Z axis shortening?

John
thank you for your post which I value
As a 71 year old student at the local college My lack of understanding of this basic subject has been exposed for what it is but your combined comments have made things a lot clearer and have provided the basis for some rational decisions.

My sincere thanks to you all for your lightning response. Your replies taught me a lot and hopefully saved me needless expenditure.

 

[kvom]

Collets for mill and lathe use are different in that on the lathe they are workholding and on the mill toolholding.

So you don't need a through collet for milling, while on a lathe you often like to have round stock that will extend into the spindle bore.

Since tools are typically standardized dimensions milling collets can be used as a set with a few standard diameters. So here R8 collets are a good choice for a mill. In addition they are easy to find and economical.

On a lathe you can have a larger size range of stock, so collets with a wider clamping range (such as ER collets) can be convenient.

 

[Tin Falcon]

yes you need a r-8 machine to accept r-8 tooling some mills here in the states come with r-8 it can be installed later there are conversion kits and it requires special tooling that can be purchased rented or made.

but does your comment mean that you DO use a draw bar with the ER32 in both the lathe and the mill? If so does the said chuck come with a threaded facility at the "narrow end" of the taper? (if that makes any sense?)

yes held into either machine with a draw bar and adapter(a large washer to hold the threaded rod center in the spindle)
I personalty have never used the thing in the lathe as I also have a 9" south bend with 3c collects.
Tin

 

[Blogwitch]

Terry,

This might explain it better.

For use on a mill you use a normal milling collet holder, and for use on a lathe you can use either a normal one, which would require a drawbar, but you can't feed long material thru, or a lathe collet holder which doesn't use a drawbar, but mounts in place of a normal chuck. With this later method, you can hold longer bars in them as they are clear to the lathe spindle hole.

Look at the centre of this page to see the two types, milling and lathe.

http://www.arceurotrade.co.uk/Catalogue/Collets/ER-Collets-Collet-Chucks/ER32-Collets-Collet-Chucks

John

 

[minerva]

kvom/Tin and John
All is now crystal clear, I will now sit down and mull over the implications upon my proposed short list of three milling machines , and see what those all important financial implications are!

Sincere thanks once again to you all for your input
Kindest regards
Terry T

 

[Omnimill]

I've got a flange mounted ER32 chuck for my lathe that allows stock up to 20mm to pass through the headstock. I'm planning on buying a MT3 or R8 mounted version for the new mill - when I get one! I got the Lathe Chuck from: http://www.glostertooling.co.uk/Download/Engineers tool catalogue.pdf Page 24 £29.95

Vic.

 

[minerva]

Vic
thanks for the Gloster link they are new to me and I will have a good look through it when I have some time to spare. I suspect you have deliberated over many of the factors outlined in the above posts and like me there are factors involved that don't necessarily have anything to do with machining.
I ordered my new mill today it comes with a short set of ER32 collets and I have almost decided to go down the MT3 route as an alternative system when I have had a play and sorted out what I need to utilise what cutters I possess!
once again thank you for your input
Regards
Terry