Anti-gravity router bit!

[weekend_woodworker]

I am obviously doing something stupid and wonder if you can help? I am trying to route some 6mm slots in some ply on my router table. I keep finding that the slots get deeper as I go across the board so they start at 6mm deep and end up at 8mm plus. It appears that the router bit is moving up in the collet whilst it is cutting. The router lift is not moving. I have tried tightening the collet up but to no avail. Any ideas what the force is that is pushing the router but up against gravity? Thanks, Mark


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[ScaredyCat]

Is the collet the appropriate size for the bit shank? Are you mixing metric and imperial?

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[Steve Maskery]

It is a pain when this happens.
It is almost certainly a worn collet - they don't last forever, unfortunately.
Replace the collet and I bet your problem disappears.

 

[Chris Knight]

Aprt from a worn collet, vibration and dirt are the usual suspects. I suggest you clean out the collet housing on the router with wirewool and the collet itself too, using a resin remover like the Trend stuff https://www.amazon.co.uk/Trend-RESIN-10 ... B00NVKRKPO. Likewise, clean the bit. Check that it is undamaged with no chips out of the carbide which can unbalance the cutter and worsen any tendency to vibrate.

Ensure that as much as possible of the cutter shank is held in the router chuck when installing it.

Check for vibration when running the router without a collet/chuck installed and compare this to when the bit is mounted - is either excessive?

You could also try a different bit. Depending on the location of the slot you want to cut, it might be possible to use a slotting cutter. These are far superior to a regular bit when grooving, but of course the usable distance from the reference edge is severely limited.

 

[sunnybob]

All of the above possibly, but first try taking thinner cuts.
say 3 mm at a time.
Ply is very grabby and with a straight cut bit you have seen the result.
There are spiral cut bits which lift the scraps away from the groove, which will also help.

 

[worn thumbs]

Try drawing the cutter out of the collet by a couple of mm before tightening it.It often happens that a shank bottoms out and the collet has nowhere to go as the shank won't let it move and isn't totally gripped.

 

[weekend_woodworker]

Hi,

Thanks for all the suggestions and advice. I hope the collet isn’t worn as I only bought the router from Woodworkers Workshop in Feb. It wasn’t cheap and I have only been using it some weekends. I have been using 1/2” bit in a 1/2” collet, so I don’t think that should be a problem. I had not put the bit right to the bottom of the slot, so if the collet wasn’t sufficiently tight I would expect it to drop not rise.

I wondered if it might be something due to differential heating, but I am not sure that explains it. I’ll give it all a good clean and have another go next weekend.

Thanks

Mark


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[Chrispy]

Please check your 6mm bit has a 1/4" shank and not 6mm, getting the wrong one is easily done.

 

[Peter Sefton]

Hi Mark

The collet shouldn't be worn but I will happily send you a new one, just send us an email.

My suggestions are the same as others, smaller cuts, slower feed speed or use a slotter/groover. I have just bought some from Wealden, so much more efficient than two flute cutters.

https://www.wealdentool.com/acatalog/On ... r_134.html

Cheers Peter

 

[weekend_woodworker]

Please check your 6mm bit has a 1/4" shank and not 6mm, getting the wrong one is easily done.

The 6mm cutter is on a 1/2” shank in a 1/2” collet so I don’t think that is the problem.


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[weekend_woodworker]

Hi Mark

The collet shouldn't be worn but I will happily send you a new one, just send us an email.

My suggestions are the same as others, smaller cuts, slower feed speed or use a slotter/groover. I have just bought some from Wealden, so much more efficient than two flute cutters.

https://www.wealdentool.com/acatalog/On ... r_134.html

Cheers Peter

Thanks, I’ll have a play next weekend and see if cleaning it and taking smaller cuts makes a difference first.


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[weekend_woodworker]

I have now worked out what what I did wrong. As usual the problem is not with the kit but the operator!

I had not put the bit in the collet quite far enough so the bottom of the bit was not below the bottom of the collet. Whilst it was tight as it was being used it must have been forced up slightly by the cone shape of the collet.

You can see from this photo that bottom was not quite far enough down. Oh well simple to fix and lesson learned!

Mark


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