Broken Collet Extension

[moorebens]

Today I tried to use a 3" raised panel router bit, for the first time.
I set the router to the lowest speed, when I then started up the router the whole thing vibrated like mad and broke the collect extension!
Has anyone got any idea why this might have happened?
Also the hole in my router table isnt big enough for the bit, what is the best way round this?
Regards
Ben

 

[brihol]

If the extension is even a little bit out in machining it will introduce a huge wobble in such a large bit, even at 10,000rpm. Potentially very dangerous, not to mention lethal. Is the bit one that cuts horizontally or vertically?
Re the hole: Is it that you don't have an insert disc the right size, because you can make new ones out of acrylic or aluminium the right thickness.
Brian

 

[monkeybiter]

Even a little bit of debris in the collet [fixed or extended] would be enough to throw the cutter out of balance, and a tool of that type at those revs will be subject to a lot of force if not running true. It's also possible that there could be a defect on the cutter causing it to be out of balance.

 

[Steve Maskery]

What is the recommended RPM for the cutter? What is the lowest RPM of your router?
A collet extension will magnify any runout and may introduce runout where runout did not exist before.
You are using your router table at its limit of suitability.

 

[Tony Spear]

I think using a collet extension with a cutter of that size is asking for trouble. If your bearings were OK before, they might not be now!

 

[dickm]

From limited experience, collet extensions are an invention of the devil. Bad enough with smaller cutters, and lethal with anything of any size.

 

[Steve Maskery]

Well I wouldn't be without my Xtreme Xtension, but they certainly do have their issues.
S

 

[moorebens]

Thank you, all very interesting.
How should I use a 3 inch bit if not in a collet extension?
The problem is not the insert but the hole in the cast iron table thats not big enough.

Regards

Ben

 

[Tony Spear]

How should I use a 3 inch bit if not in a collet extension?
The problem is not the insert but the hole in the cast iron table thats not big enough.

Regards

Ben

From this I take it that your are trying to spin a 3" dia. cutter totally above the table because you can't get the cutter any lower than table height?

If so, you need a bigger 'ole or a new table! :mrgreen: