router collets

[steveakam]

The box says "6.35 (1/4")" so I think ill look for 1/4" bits. my search throught machine mart, focus, b&q and other web sites seem to through up tons of matches for 1/2" & 1/4" bits. didn't see many with a 8mm shank.

I hadn't realised you had to hold the switch all the time what a pain. another obstacle to overcome. I do have some small G clamps I picked up at the car boot the other week.

 

[Chems]

Yes I thought that was the case with our router.

 

[John. B]

I go along with Paul & 9fingers.
using 1/4" shanks in an 8mm is a dangerous practice, use the size of cutter that relates to the collet.
A quick phone call to Wealden who manufacture cutters will tell how safe or unsafe the practice is
BTW. you can get a small velcro strap that will go around the trigger switch to save holding it.

John. B

 

[Chems]

We are saying 1/4 inch in 6mm not 8mm. An its not 6mm its actual 6.35mm which is exactly 1/4 inch!

 

[brianhabby]

Having to hold the switch on is a safety measure - it forces you to switch the machine off when you put it down - not a bad thing.

When they started doing this with new routers I thought 'what a pain' but in practice you soon get used to it, it doesn't bother me now.

If you are using your router in a table though, then you will have to find a way to hold the switch on.

regards

Brian

 

[9fingers]

We are saying 1/4 inch in 6mm not 8mm. An its not 6mm its actual 6.35mm which is exactly 1/4 inch!

I am at a loss as to how to make this plainer but here goes.

The type of collet used by routers is only designed to have a very small range of sizes that it can accept. Possibly no more than 0.1mm (0.04")
Its function is to grip whilst maintaining concentricity far better than something like a drill chuck which has the ability to accept a wider range of diameters but has relatively poor concentricity.

Our router collets must be used with cutter shanks that have the same nominal size as the collet. 6mm for 6mm, 1/4" for 1/4" and 8mm for 8mm and so on. End of story.

Bob

 

[Maverick.uk]

I have made collets and they are manufactured so that at the correct position within the spindle when pulled up the size is correct to match the mating part within a very tight tolerance. This means as another poster has suggested good concentricty etc etc but also that the contact area for the mating parts is completely around the circumference of the collet that is in contact with the cutter shaft. In our scenario this means transfer of the driving forces of the motor through the shaft onto the cutter. It alos has the job of safely keeping the cutter in the collet whilst completing this.

If we change the size of the shaft on the router bit from 1/4" say down to 6MM it will mean that we no longer seat correctly completely around the circumference of the shaft on the cutter. This means that we reduce the grip on the cutter shaft and introduce a potential for the router bit to move under load. Not somethign i would want at the speeds these pieces of kit run at.

Cheers

Mav

 

[FatFreddysCat]

8mm is 5/16 but I've never really understood what 8mm bits are for.

In the UK our measurements were Imperial at one time, so our standard router bit shanks were 1/4in, 3/8in and 1/2in (6.35mm, 9.53 and 12.7mm) in the main. The 3/8in ones have pretty much disappeared but you'll still find a few sizes offered in 3/8in shank, mainly for specialist machinery. In most of Europe they went metric, oh somewhere around the time of Napoleon, so their standard router shanks were 6mm, 8mm, 10mm and 12mm. 10mm have all but disappeared except for CNC routers, but the other three persist.

The reason for 8mm over 6mm for some types of cutter is strength. The cross section area of a 6mm cutter shank is 28.3mm2 (1/4in is 31.3mm2) whilst 8mm shanks have a cross section area of 50.3mm2. So they will be stronger. Probably why Leigh dovetail jig cutters are offered in 8mm shank as well as 1/4in. And as others say it can be dangerous to use a spring collet with the wrong size cutter shank. Most often the bit will end up shaking itself loose and dropping out. That can mean a ruined workpiece at best.

 

[steveakam]

found a nice little link that maybe useful.

http://www.raygirling.co.uk/routtips.htm

dug the router bench out of the back of the junk shed. (god theirs a lot of junk in their) put it all together and the new router fits in nice and snug,

now just need nice weather to sort out my old shed/new workshop.

 

[Krysstel]

The reason for 8mm over 6mm for some types of cutter is strength. The cross section area of a 6mm cutter shank is 28.3mm2 (1/4in is 31.3mm2) whilst 8mm shanks have a cross section area of 50.3mm2. So they will be stronger.

Being based in a metric country I had until recently only ever used 8mm cutters in my Elu 96. However, since discovering Wealden I've been buying 1/4" shanks from them (+ a new 1/4" collet & nut for the Elu !). I was shocked by the obvious cross sectional difference between 1/4" and 8mm and it struck me that surely it would be better for everyone if the 1/4" shanks were dropped in favour of only 8mm. Especially since there's no problem fitting an 8mm shank in a router designed for 1/4" - all you need is an 8mm collet.

Wealden do quite a lot of cutters with 8mm shanks, as do MTMC (Trend ranges). Trend also sell a range of collets in sizes; 1/4" (6.35mm), 8mm, 12mm, 1/2" (12.7mm). Or you can use a reducing sleeve to use 1/4" shanks in an 8mm collet or 8mm shanks in a 1/2" collet (I know it's not good practice so no comments please ......!)

 

[9fingers]

Not all routers that will take 1/4" bit will accept an 8mm collet but generally speaking if you can use 8mm then they are better than 1/4".
I doubt if the cost is much greater.

Bob

 

[Krysstel]

Not all routers that will take 1/4" bit will accept an 8mm collet but generally speaking if you can use 8mm then they are better than 1/4".
I doubt if the cost is much greater.

Bob

Really ?
Must admit I assumed it was so since I doubted any router was smaller than my Elu 96.
Price wise there's no difference at Wealden although their range of 1/4" is more extensive than the 8mm - hence why I've started buying 1/4" instead.

 

[JMcK]

Had a search and excuse me resuscitating this thread.

I recently purchased a cheapie router. It's an "Ideal Power" Chinawese product. However, it seems quite reasonably made and I got it for dedicated use in my router table. (It was bought on the basis of the price making it disposable).

As it was supplied for the market here it has a 12mm nut and collet as standard with some reducers.

I have a Makita 3612C which, as you know, takes a 1/2 in collet.

Having had a play around, the new router will accept the Makita collet and nut as it has the same thread. It will also lock a 1/2 in cutter and the shank of the 1/2in cutter slides in easily without any binding.

It would suit me to use my 1/2 in cutters in the table but I wonder if I am missing something. The cheap router is 1800W and is solid enough.

Bearing in mind that it is using the complete collet and nut assembly I would be interested in any comments. Thanks.

 

[Digit]

If it grips the cutter shank it should be ok, but test the arrangement by seeing if the cutter can be deflected sideways under pressure. If it can either the collet is being gripped at only one end or the cutter is. Hope that's clear.

Roy.

 

[JMcK]

Yes that's clear. Will have a look at that. Thanks.