Mill collet question

I'll add a bit to what stevecmo said (which is all good info).

2) Opinions vary greatly on whether toolholders are better, or collets (great taste!, less filling!). Let's break it down

* Holders are more expensive, and last longer. If you have mills with flats (weldon flats), they are _less_ likely to slip or pull out. They tend to have poorer concentricity than collets, which becomes a big deal on smaller end mills. If you leave your mill in the holder, you can remove it from your spindle, and replace it, and the z offset will not change (they have repeatability).
* Collets are cheaper, and have better concentricity. If you don't practice good collet use, you can get pullouts, or the mill can slip. Once you loosen the collet, you need to touch off on Z again (no repeatability in z).

3) ER collet holders combine the best of both worlds, the repeatability of a toolholder, and the concentricity of a collet. You only get the repeatability if you pull the whole holder out, leaving the end-mill intact in the collet. Some folks use them just like R8 collets, because they don't like reaching up to release the drawbar to change tools. This is more of an issue on a knee mill than on a desk/benchtop machine.


Speaking of good practice with collets, if you have not seen this document from Tormach, I highly recommend it, even if you are not using TTS tools

http://www.tormach.com/uploads/163/TD31090_ToolHolding-pdf.html
 
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I purchased mine from Shars and they are okay. However, I do not like R8 collets. I'm short and fat, changing collets is a royal PIA. My shortness and my machine tallness do not get along. I have switched over to DA 180 collets. They cover the same range of sizes, but the individual collets seem to have a greater grip range, so they can been used with drills. However, I still need the R8's as I sometimes do not have adequate "daylight", which the DA's and ER's consume and R8's don't.

Bill
 
I'd go with an import set of collets available from any of the tool houses (Enco, KBC, Wholesale tool, etc). When I got my first lathe, I made the mistake of spending a ton of money on tools, without actually knowing what I would need, much of it was used, but a fair amount was unused or underused.

Get the basics, pick a project, and if you discovery you are missing a tool, buy or make it when the need arises. The (second) most important thing (after safety) when you are first getting started is to make some chips.
 
I should have mentioned this before, but your question was directed towards the mill. Another advantage to the ER collets is you can use them on the lathe too assuming you have one.

Steve
 
I have the R8 collets as well as several sets of ER-style collets with collet chucks. I bought a basic set of ERs with an R8 chuck after I got the ZX-25 mill/drill. Right after that, a friend asked if I wanted a full set that he had for sale, also R8. After using the basics (every 1/8") for a while, I bought his set (every 1/16"). Lots more useful, but a different format.

When I got the Victoria (MT3 spindle), it came with a set. A few sizes were missing, but guess what? The set I got from my friend was the same format - European, IIRC. BTW, my X2 mill (now CNC) and my lathe are both MT3, so the collets can be used virtually everywhere in the shop.

Now to the point. If you can, save and get the full set. As mentioned, it will hold some drill bits when necessary. The R8 collets are good, again as mentioned, when you need to conserve space from the spindle to the work. Other than that, if you can only afford one set initially, I'd advise a collet chuck and ER40 (or whatever number) collets. Lets face it, the nature of our addiction will have you getting the rest later anyway. :lmao:
 
Thanks to all

I just ordered a full set (13 pcs) of R 8 collets & 2 tool holders 3/8 & 1/2 for mills that I have
Ordered from Shares.

so soon on to chip making
 
So, another newbie question - i know the difference between mill holders that you buy by size of the shank and collets are used to change and are more accurate - my question is "what meant by a spring collet and please let me know what the difference between ER-25, ER-40, etc. should I save up and purchase a spring collet set, is the ER number the quantity of collets in the set. Please provide confirmation.
 
Pmedic828 said:
So, another newbie question - i know the difference between mill holders that you buy by size of the shank and collets are used to change and are more accurate - my question is "what meant by a spring collet and please let me know what the difference between ER-25, ER-40, etc. should I save up and purchase a spring collet set, is the ER number the quantity of collets in the set. Please provide confirmation.
Click to expand...

I would say that technically all collets are "spring" collets. They have some type of slits/slots in the end that close down on the part being held when drawn into a taper - either using a draw bar on an R-8 or a closure nut on an ER. There is one version that uses rubber with steel ribs molded in for the "spring" (I can't think of the name......names is hard as you get older :whistle:).

The ER-xx is the size of the "system". The larger the number the larger collet / part you can hold. Here's a link to ER info:

http://www.workholding.com/Pg30_ERCollets.pdf

Steve
 
outsider347 said:
Joe
dumb question

What is a square and hex collet block?
Click to expand...

I have used them. They are collet holders that are ground square or hex shape for shops that don't have indexing heads. Good for small parts that need machining on Bridge Port type milling machines. The shop I worked in the holders were stored in a small wooden box.
 
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