collet extender shocker!

Help Support

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.


Established Member
12 Jan 2003
Reaction score
bought the collect extender (along with my other B-day pressies) from axminster (yup the one in the review mag that I just got thru for 20 squid).

all looks good (CMT i think...) very big and chuncky, but there-in lies the problem its TOO LONG!

I`ve gone from hardly having my raised panel bit in my router collet (did I really use it like that :shock:) to having the raised panel bit 10mm above the table with the router full lowered :cry:

so after a bit of head scratching I made a false table top and hey-presto we`re good to go. The raising panel bit seemed fine although i did notice a FAR bit of deflection when the bearing touched my panel :?

problems came when I wanted to mould the stiles and rails. (single bit)
I seemed to get alot of "judder" i.e. no mater how smoothly I tried to push the stile/rail thru the cutter (lots of hold-downs etc) it seemed to judder, not alot bu tI noticed enough so that i got extra amounts of tear out. I presume this is caused due to the deflection of the bit(?) setting up some oscillation(?)

overall a little bit disappointed.......

anyone else had the same?

I bought a CMT extender and don't like it at all. Loads of trouble finding the right size spanners, and there seemed to be quite a bit of extra vibration
What router are you using it in? I suggest an extender is only going to work well in a high-quality router, as routers are generally not designed to have the cutters - and especially big heavy panel raiser cutters - whizzing away so far from the bearings. Nature of the beast, I think.

Having said that, if you ARE using a good router (I use a MOF177e with the Xtreme Extension - excellent), then you should be able to get satisfactory results. Have you tried taking the speed down as low as it will go? Do you still get vibration even when it is not under load? If so, it suggests that something, somewhere, is out of balance.

am using the BIG freud, no problem what so ever when not under load (no vibration).

am sure nothing is wrong with the router, have seen the extreme jobbie in a mag once but did`nt know much about it, any info on the web about it?

john> how do you get around the loss in height of your router plunge due to the table when you raise panels?

I have used a CMT collet extender for a long time and more recently an extreme extension (both used with with an Elu 177 and a DW 625 - same router different colour). I find both extensions introduce more vibration than is apparent without them but neither is unacceptable.

The extreme extension's method of securing the bit is so quick and easy, I tend to leave it in place for most of my table routing - I just wish that router manufacturers would make something as easy to use as an original part of the router.
Steve, the ExEx is sold in this country by The Woodworkers Workshop. Its a one-man-band, so service is either excellent or very poor (I've experienced both) depending on how busy he is. As someone who is self-employed I have some sympathy with his predicament. His website doesn't tell you much technically, although there is not much to tell. Put it in the router, job done. Cutter change is done with a T-allen key, very quick and very easy. Takes 1/2" and 1/4" cutters. Very high quality, very well-made, pretty expensive for a little chunk of steel, but Does What It Says On The Tin, superbly.

chris, steve > don`t you find that you get too much extension? did you have to put a false top on your router table or does my freud just not have enough "lowering capacity"

chris> you said that you have the CMT
I find both extensions introduce more vibration than is apparent without them but neither is unacceptable.
do you find that you get more tear out than when not using the extender?

would the xtreme jobbie be worth a look at or am i pretty much going to get the same results as with the CMT?

when routing 10 sets of stiles/rails i found that 3 stiles had suffered quite bad tear out and could`nt be used (lower edge of o-gee tongue), I was quite disappointed as I`d graded all of the stock and choosen the straightest/best for this purpose :?

is this usual?


I do not get any more tearout using either extender. As Steve Maskery said, what is your router? I suspect that a budget router may have inaccuracies in the bearings department etc that are magnified by any extension and thus a change from one extender to another won't help. Moreover the Extreme extension is more massive than the CMT extender so that it may even cause more vibration thatn the CMT - unless of course you have a duff extender which, given its simple design, I suspect is unlikely.

I would look at your technique, taking lighter cuts as a starter.

Sorry - just noted you mentioned a Freud router - I have no personal knowledge of this router's quality although of course many folk like it.
The only cutter I have had this problem with is a very big hefty and LONG bearing-guided flush-trim cutter, when I wanted to ue it to cut a rebate, and yes, it wouldn't go down far enough. But that was my fault for being too lazy to set up my rebate cutter with the right bearing. Swapping to a standard-sized straight cutter did the trick.

I have the Freud FT2000 which seems fine when not using the extender.

we are talking about tiny differences here, just enough for me to notice and obviously enough to cause some extra wasteage, just wondering if this is all normal? anyone?

it would seem to me (from the website pictures following Andy`s link) that the xtreme jobbie has no way near as much "extension" as the CMT version, not a problem for me but obviously would produce less deflection (leverage via moments..... back to o level physiscs again!)


I (also) use a MOF177e with a Xtreme Xtension - and don't get any perceivable vibration on any of the bits I've ever used in it. (Plus the quick release mechanism has transformed my table routing experience!)

The XX does give instructions on ensuring the collet is located dead centre in the collet - you can see for yourself here: pdf/Runnout & Whip.pdf
and here: pdf/Extension inst full size 3.pdf

May be worth going through the same procedure with your extension?

My other thought is whether the extension works better with any other bits? Could the bit be at fault?


the bit seems fine if I use it without the extension *cough cough* not "fully" in the collet though :shock:

I tried reducing the feed rate to REALLY slow and this helped a little.

I`ll try the instruction supplied in the link! , cheers


I doubt you'll eliminate the vibration/deflection whatever cutter you fit. Collet extenders are a compromise solution. You are compromising the maximum speed/mass of the cutter that can be run smoothly, and the depth of cut. I quickly discovered this after buying the CMT extensions and like you, questioned everything else I could think of. My successful solution was to modify the router mounting to avoid the need for an extension. I'm left with 2 CMT extensions, which IMO are about as useful as a chocolate teapot. To anyone else I advise, buy only as a LAST RESORT, don't expect it to work very well, and then you definltely won't be disappointed.


Would it be reasonable to conclude from this thread that those of us who have the XX are very happy with it (Andy and me) and those who have the CMT are somewhat disappointed? Not having an axe to grind against CMT or anything, I have a lot of their bits and am very happy with them, just wondering if that was a fair conclusion to draw.
looks that way!, although i was just quoted 60 odd quid for the xx :shock:

i mean bloody hell, is it made of gold?

I'll put up with a bit of extra tear out for that price !
I am happy enough with the CMT in terms of vibration or lack of it but of course it doesn't have the nice feature of the XX as far as mounting bits is concerned

Latest posts