Clarkson Type Threaded End Mills

[SteveW]

Guys,

I needed to dip into my little drawer of unused end mills to complete a little job, all cutters bought from our usual suppliers.

At first I thought the (new, never used before) 1/2" collette thread was duff because none of my cutters would screw in until I found another drawer with a 1/2" cutter that did fit.

Turned out that three brand new cutters had insufficient depth of thread so wouldn't fit. These three are only good for an ER type chuck.

Tip: When buying these things don't just check the sharp end. Check the thread at the other end is good.

[houstonceng]

I did overhear one exhibitor at the London Show (Ali-Pali) one year telling a potential customer that the threaded end-mills on the stand were only cheap, because they didn't fit in Clarkson (and equivalent) auto-loc chucks. They were being sold for use in ER collet chucks, etc. Otherwise, they appeared to be a good buy.

Can't remember for certain who the sellers were, so won't try to name any.

Perhaps these were they ?

[jonkett]

Buy a greenstock blank with whatever taper your machine needs. Drill and ream or bore a hole in the soft end to whatever size your cutter shank is, tap a 6mm hole or what convenient size tap you have for a socket set screw, grind a flat on the shank of the cutter and bingo you have a side lock holder for less than a tenner, in about an hour. Then it doesn't matter what thread size the cutter has.

Better still buy an ER32 collet chuck and three collets and you have a far superior milling chuck in accuracy and holding power than an Autolock type chuck, they are way passed there sell by date now and it doesn't matter what shank or thread is on the cutter or if it is metric or imperial.

[bantamman]

That's interesting!
There's quite a selection of different collet chucks available and it's a bit of a minefield for the novice. I have been trying to decide on a set to buy but couldn't be sure which was best. I will only be buying one type so I want to get it right!
As a beginner I will be doing straightforward milling jobs on the lathe for quite some time but would still like to get an accurate setup that I can "grow with" as skill improves. I don't have a milling machine.
Any further advice would be most welcome.
John

[44767]

Hi All,

As a way of being able to use the cutters you have may I suggest that you grind an undercut at the end of the thread so that it will screw in far enough into the Clarkson collet. That is if the thread is the correct size at all. It doesn't need to be pretty and could be done off-hand on the bench grinder. The collet will still be gripping on the parallel part of the cutter shank.

[SteveW]

Mike,

A while back I bought an ER32 collet set with an R8 holder for my Mill/drill and also bought an ER32 collet thingy for the lathe plus a back plate.

The net result is a plan B for my duff screwed end mills and a very useful collet system that ranges from somewhere around 2mm right up to 20mm for the lathe.

The collet system is also very useful for the solid tungsten tooling I see on the JB Tools stand at the MEXs. I was first introduced to these folk by an old guy by their stand. He explained that he bought a couple of these tools a year and they saw him through the year without having to sharpen them.

[44767]

Steve,

You'll find now that you have an ER collet system that it is very useful. Now of course you can hold any cylindrical part in it including drills so you're not constrained by a few intermediate sizes. Also since there is no need to manufacture cutters with threaded ends, the tooling is much cheaper.