# router collet extender = lathe extender?



## rafezetter (8 Apr 2015)

Can anyone give me a logical reason why router collet extenders like this:

http://www.amazon.co.uk/Charnwood-C...=1428479517&sr=1-80&keywords=COLLET+EXTENSION

Cost £35+ (up to about £60)

when a Milling lathe collet extender like this:

http://www.amazon.co.uk/C16-ER-100L...=1428479388&sr=1-36&keywords=COLLET+EXTENSION

Costs just £13+

And has anyone made one?

I'm just curious because as far as I can see they are the same damn thing.

Edit 10 mins later: couldn't you just buy a c20 er20 100l lathe extender (google is wonderful for education) and turn down the end to 12mm to fit the router collet?


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## adidat (8 Apr 2015)

The second one is a morse taper to fit a taper on the motor or drill press etc, the other isn't. also the milling one may only be rated for about 5000 rpm where as the router one could go up to 20000 rpm +, 

just so you know I'm pretty sure a router shank is 12.5 or 12.7 rather than 12 mm, unless you have a 12mm European collet

Adidat


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## chipmunk (8 Apr 2015)

rafezetter":3k3jndc9 said:


> I'm just curious because as far as I can see they are the same damn thing.
> 
> Edit 10 mins later: couldn't you just buy a c20 er20 100l lathe extender (google is wonderful for education) and turn down the end to 12mm to fit the router collet?



I think you're right though.
...and that's in principle all the Axminster one is http://www.axminster.co.uk/axcalibe...trq4pZ_9301XGitXbUo36xIbYybYw2XYGxhoCNFHw_wcB

Although the collet nut on the Axi one looks to be the same as that on the Junior Woodturning Chuck which is not a standard ER collet thread or standard ER collet nut size and doesn't eject the collet as well as the proper nuts IMHO.

Jon


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## pcb1962 (8 Apr 2015)

rafezetter":27dx4qwg said:


> couldn't you just buy a c20 er20 100l lathe extender (google is wonderful for education) and turn down the end to 12mm to fit the router collet?



I'd expect the shank to be hardened, it would be very difficult to turn down on a hobbyist grade lathe.


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## chipmunk (8 Apr 2015)

pcb1962":2irzg0h1 said:


> rafezetter":2irzg0h1 said:
> 
> 
> > I'd expect the shank to be hardened, it would be very difficult to turn down on a hobbyist grade lathe.



Not a serious problem really. 
There are a couple of obvious options...
TCT tipped turning tools or heat it up and anneal before turning.
Jon


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## AES (8 Apr 2015)

As I'm just learning from other Forum members (see my thread in General Woodworking under the title "Help with Collet Routers .... ") there seems to be quite some difference between "engineering" collets and Router collets.

For a start size ranges - my original post in Gen W W'ing asks why my 12 mm capacity Router collet will not accept a 12.7 mm shaft router bit, after all, it's quite usual to have a range of at least +1 mm above nominal capacity with engineering collets. No so with Router collets I'm advised - a 12 mm capacity Router collet (which mine is, being "European") should NOT be expected to even accept a bit with a 12.7 mm shaft. And vice-versa, a 12.7 mm (half inch) Router collet will NOT grip a bit with a 12 mm shaft properly.

For info, depending on who/where you buy from, Router bits are "commonly" available in ranges with 6 mm shafts; 6.35 mm shafts (quarter inch); 8 mm shafts; 12 mm shafts; and as above, 12.7 mm (half inch) shafts - not all manufacturers have all shaft sizes in their ranges. In all cases you need a Router collet of the exact size to fit the above (or at least an adaptor for things like 12 mm to 8 mm, if you don't mind using them - some advise against). And you need to buy extra Router collets from your Router manufacturer if you need to cover the above ranges - e.g. Festool Routers in Switzerland come with a 12 mm collet as standard, in the UK, the same model machine has a 12.7 mm collet! 

In other words I don't pretend to understand it fully, but apart from the difference in typical rpm on a lathe (3,000 max?) and on a Router (25 -30,000 ?), it's also clear that the Router collet is working within a much smaller dia range than the engineering collet.

I must say I also do agree with one of the other posters above - personally I certainly wouldn't care to try turning down an engineering collet mandrel as proposed, at least not with a "hobby" lathe - I'd expect it to be "tough as old boots"!

Don't know if any of that helps, but hope so.

Krgds
AES


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## chaoticbob (9 Apr 2015)

Rafezetter - No logical reason as far as I can see. I have an Axi router extender, cost me about 35 quid I think, - it's just an ER 20 engineering collet chuck on a 12.7mm parallel stick. Arc Euro do an ER16 collet holder on a 12mm parallel shaft, but ER16 only goes up to 10mm collets, so OK for quarter inch router cutters but not half inch. I very much doubt that rotational speed is an issue - engineering chucks are designed to withstand far higher radial loads than encountered in cutting wood. I agree with Chipmunk that carbide tooling would cope with turning down the shank.

AES - engineering collets in the ER range are designed to grip parallel to the workpiece or tool to within 1mm _below_ the nominal diameter. Router collets aren't made like that AFAIK. It would be courting disaster to force the wrong size bit into one.
Robin


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## rafezetter (9 Apr 2015)

I saw a router extender - labelled as such - that said it required a separate er20 collet, which is what led me to the lathe extenders in the first place, and as you say they are labelled to have a 1mm grip range.

I wasn't aware of the 12mm - 12.7mm router bit issue, but might explain why a bit I used the other day was slipping down into the collet when I put pressure on it until it bottomed out.

I hate having to pay through the nose for something that is all but identical to a much cheaper item....


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## AES (9 Apr 2015)

@chaoticbob:

QUOTE:
.... to within 1mm _below_ the nominal diameter.
UNQUOTE:

Quite correct, brain fart here, sorry.

QUOTE:
Router collets aren't made like that AFAIK. It would be courting disaster to force the wrong size bit into one.
UNQUOTE:

Also correct. In fact on my 12 mm Router collet just as an example, you couldn't physically get the collet to open up big enough to accept a 12.7 mm bit shank anyway. The potential danger is in fitting (say) a 12mm router shank into a 12.7 mm collet - it would obviously fit but according to the info I now have from other members here (see my other thread, mentioned above), it would not grip the shank safely - in fact one of the posters above seems to have had exactly that problem!

I'm NOT trying to justify the high price of Router collets and extenders/adaptors, the OP may well be right, I don't know. BUT to me it seems obvious (without any maths) that a Router collet turning at say 20,000 rpm would have more force on the shaft & collet than turning in an engineering lathe at say, 3,000 rpm at the most. Add to that the fact that "normally" one is REDUCING the diameter of the work piece in an engineering collet scenario, whereas in a woodwork router one may well be turning a bit of, say 30 mm cutter dia on a say, 12 mm shaft (panel raiser bit) at possibly 20,000 rpm or more, then I reckon the forces on the Router collet must be higher, even allowing for the fact that a metal work piece is "harder" than wood.

But as I say, I'm not trying to justify what may well be unnecessarily higher prices for Router collets, I'm just trying to point out that I've just learned that unlike engineering collets, Router collets do NOT seem to have a capacity tolerance.

HTH
AES


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## chipmunk (10 Apr 2015)

The speed issue is a red herring IMHO. 
Provided the collet runs true then there shouldn't be any problem at all, and any metalworking lathe in the hands of an anywhere near competent operator ought to be able to turn the shank of one of these things down to 1/2" to within "a gnat's" of true. The existence of the Axminster extender is proof positive that these ER collet-extensions work. The only difference is the collet nut and IMHO the Axminster one is actually inferior to the small ER-20 engineering collet nuts. 

The real problem with these extensions is the extra leverage imposed onto the router spindle by the longer effective shaft in use. I think this'll just mean the router bearings will fail earlier if lots of heavy cuts are made. 

The extended closure range of the ER collets comes about because in an engineering context the collets were originally designed for gripping stock rather than tooling and in that application you want as few collets as possible to cover the entire range of material. That's why the collets have so many slots when put beside router collets. ER collets obviously also work well for tooling too though and since they're so cheap why not? 

In routing it's possible to design a very cheap collet for one size of tool shank. These usually only have very many fewer compression slots in them and really only expand enough to allow the tool to be inserted and withdrawn. When they're worn of course it's a chance for the router manufacturer to charge us for an expensive replacement collet or get us to buy a new machine.

In an ideal world IMHO. all routers would use ER20 collets or perhaps ER11 in palm routers and we'd be able to use any size tooling in the router provide we had the correct £5 collet.
Jon


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## rafezetter (10 Apr 2015)

Does anyone have an ER20 to see if it will fit into a router that normally takes a 1/2 collet?


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## chipmunk (11 Apr 2015)

rafezetter":193pp3ec said:


> Does anyone have an ER20 to see if it will fit into a router that normally takes a 1/2 collet?



Sorry to say it almost definitely won't fit precisely enough. 

To tighten correctly all ER collets need a precise 16 degree internal angle in the body and another taper on the nose end which is part of the nut. Without these angles the internal grip of the collet won't be parallel along its length and therefore unsecure.

Jon


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