Thread: collets

I am scratching my head about milling collets. I havent quite decided on which machine to get but suspect that something like a HM46 will be the eventual winner. I am making a list for Santa (probably next Xmas!!)

I am reading Harold Hall's book on milling and he points out that the Clarkson (threaded) or Posi Lock (have a flat on the shank) system is safer because the tool cannot work free.

The ER type dont seem to have any means except friction for stopping the cutters from migrating down but yet they seem to be the new standard.

The Posi Lock gear is still available (more so than the Clarkson it seems). Are there any strong opinions.

Obviously I am a newbie to milling and have no genuine need for a mill except that I keep wishing that I had one as my lathe projects become more adventurous.

When you wish upon a star!

ER type....

I have a Clarkson. All the Clarksons I have seen are very pricey. That would be enough for me to go with ER if I was replacing it. The cutters also tend to cost more.
A set of ER collets also be used for work holding(in your lathe maybe)
Can you get Clarksons with MT3?

Stuart

If you are going to be in the market for a mill around the size of the HM46 it might pay you (literally) to keep an eye on this seller on Ebay. This company is actually Standaco in Rooks Rd Nunawading Vic.

I bought my DM45 mill from them last month for a lot less than a HM46, it has an R8 spindle which would give you the option of using R8 collets. CDCO in the US sells sets of these for a reasonable price.

I have a set of ER collets already and have now purchased an ER-R8 collet chuck from CTC Tools in Hong Kong, for $30 delivered.

I would get er collets, they are more helpful and good for setting work up, as you cna hold a dial indicator in them and usually the cutter runs truer in them then a clarkson, I use a clarkson at work and our cutters dont have flats on them but they wont come loose as when you cut if it slips it will screw up the thread more and make it tighter.

Harold is right in what he is saying, but the ER type system are the best all round to have and can hold end mills, drills, taps etc. They can be used in the lathe as well and are a lot cheaper to buy over the other from places like CTC.
Results for Tool & Work Holding:ER Collet Chucks

A lot of the problem with the end mills coming out of ER's chucks is because people don't do them up tight enough. The tightening torque for ER32's is around 110 ft-lbs and ER40 is around 130 ft-lbs, so they need to be tightened up a bit. It is best to use a bench fixture to do it safely like the one in the link below.
https://www.machineryhouse.com.au/Pr...stockCode=T320
I have had end mills pull out myself but it has been my own fault from not tightening them up enough. What happens is the end mill acts like a screw with it's flue's and pulls the end mill out of the chuck if it can.
You can also get end mill holders to suit different spindles, they hold the end mill by 1 or 2 grub screws onto the flat on the end mill and go strait into the spindle, eliminating a chuck all together. Some say they are superior to collet chucks because their are less parts between the spindle and cutter which reduces run out, and then the other camp say they push the end mill to one side causing run out.

This link below is a good one about the advantages of ER collets.
Lathe Tools - Collet Chucks - Millers Tooling, Brisbane, Australia

Dave

Er collets hold a larger range of shank sizes ,they will hold metric and imperial .They are made in metric and imperial , but really a set of metrics will do all the sizes ,just depend what the largest size cutter shank you plan on using .
ER 32 1mm - 20mm ,ER40 go up to 1" IIRC
For the home machinist they are the ducks nuts.
With the Clarkson or Posilock you are restricted to standard cutter shank sizes usually 1/8" increments, which is ok but the ER collects can be used in the lathe to hold drills and reamers ,and also in the mill they have a 1mm range on each collet.ie a 13-12mm collet will hold any size between.
The ER collets are split from the front and the back and clamp the full length of the collet.
I've never had a cutter or drill come loose in my ER collets , but I have in the old standard type collet because of thier design.

Kev