On mills without spindle locks ER collet chucks can be a bit of a balancing act to tighten without the cutter falling out. You have to prevent the chuck from turning with one spanner, tighten the nut with another and prevent the cutter from falling out with your third hand!!!. With the Clarkson the screwed shank hold the cutter in place before you tighten the chuck. It also does not need to be tightened as much. I manage quite happily on my Myford VMC by holding the belt when nipping up the Clarkson. With the Sieg at work I have to resort to supporting the cutter on the milling vise.

regards Martin

I use a ER32 chuck on my VMC mill and it works well. Ball bearing collet nuts make things easier. I also have an ER32 Lathe chuck, collet blocks and a spin indexer, it's a very useful system IMO.

I have both – well the Osborn 'posilock' type & ER25.

Both are fine but I find the Osborn is more convenient to use for cutters, it also has more mass which helps, although that means less daylight under the cutter. I need to get a set of metric collets for it some time.

Only the ERs are suitable for workholding, at which they excel.

Neil

If I had the Tom Senior Mill I would use ER collets,keep the Clarkson just in case one gets a key way or similar to cut in really tough material ,the Clarkson will not let the cutter slip,though the ER collets are very good, when I did my training the Clarkson was the norm and a foolproof system,my old boss reckoned that the Clarkson system had overcome the problems with a multitude of previous methods for securing cutters,which had gripped either too tight and were difficult to removed or slipped and ruined the work,the only snag with a Clarkson was that it could not grip a smooth shank tool . Collet systems were developed to hold smooth shank tooling mainly solid carbide cutters , With my turret mill with 30 int spindle, for 25 years I have occasionally used Clarkson holders,but the regular choice is Bristol Erickson DA collets, which hold screw or plain shank tools, but do occasionally slip under difficult conditions, tightening does require two spanners and luck , if the cutter is tight in the collet then no problem, if it is a slip fit then its a fiddle ,when releasing the collet I usually let the cutter drop onto a large lump of rag.I would not use a spindle lock or engage low range when applying any force on the spindle, not worth the risk of damaging the machine. The choice of Bristol tooling at the time was that I acquired them from a friend for a few notes. I have recently purchased some er25 collets for work holding i.e. threading studs with coarse threads which always slip in chucks and holding taps and slot drills really tightly in the lathe tail stock, they do their job so well that they must be ideal for holding cutters in the mill, and are superior to double collets (DA) .

Thats what I said Russel "With the Sieg at work I have to resort to supporting the cutter on the milling vise."

Martin

Lots of my cutters are a snug enough fit or easily clamped with the ball bearing nut but one or two that aren't are easily supported with my middle finger whilst my thumb and forefinger hold the ER spanner. My left hand holds a conventional spanner. It's a natural enough skill for an ex mechanic!

Why can't you hold the spanner with one hand and support the cutter with a couple of fingers of the same hand. That leaves the other hand free to tighten the collet sufficiently to nip the cutter. Then you can tighten the cutter fully.

I do use MT collets in my mill because that's all I could afford at one point, they are more ridgid. I also made a self ejecting draw bar.

Hate with a passion the Clarkson and ER so not the best advice.

Clarkson have to use threaded shanks but don't drop out. Change cutter shank size have to unscrew the clamp off to change the collet, same as ER.

ER just never ever hold no matter how much they are grollied up, constant cutter dropping having had three sets one Chinese cheapy Chester real naff barely usable, some better quality forget the name and Wabeco.
Then need at least two hands to undo and tighten back up.
Wont mention the extra load placed on spindle and less available height.
The only good thing about ER is ability to hold Weldon or any type of cutter but same said of MT and R8 collets.

Next mills an R8 with collets similar to what have used the last 17 years, by the time picked up both spanners for ER, the R8 and MT cutters out, by the time put two spanners on the ER ignoring the excessive grollying up, slipping and knocking in to something has happened a few times, machines up and running with MT and R8 collets that never ever move.

Now lets face the fact, when need to drill, bore or use other tooling those that are so hyped up on ER and such like have to remove any way and use the MT.

Hi steamer1915. I do know how to tighten up an Autolock. They just seem to hard and the cutter top breaks.

I have amongst my accumulated tooling 'stuff' , a clarkson attachment to convert a 16mm or 5/8" collet holder into a 6mm or 1/4" sidelock cutter holder. I'm not sure if other sizes are available, but I have found this an extremely useful bit of kit over the years. Offering the best of both holding systems. Roy M.