Router cutter problems

[JeremyB]

I have a Gifkins dovetail jig that I have not used very much at all, and today I experienced a repeat of a problem with the bearing below the router cutter head. I have my router securely fixed in a table and today when using the jig, the bearing started to come apart. I think it is just a dust seal that has come away, but I stopped immediately in case it all flew apart. This is the second bearing that has come apart and I am at a loss as to why.

The bearing spun freely and I had previously added a small drop of oil as advised by the jig designer. I run the Triton router at max speed and I wonder if this could be the cause. The jig instructions make no mention of speed.

Can anyone help please.

PS
Rang Wealden tool for a new bearing and they have put four in the post today and they should be with me tomorrow. What a good company. Cheaper than APTC

 

[Myfordman]

Generally speaking the bearings on router cutters are quite poor quality. Due to design constraint of large bore/small OD, the balls are very small indeed and I suspect have no room of cages. The also go at one hell of a speed.

+1 for Wealden - excellent firm to deal with. They now get all my router cutter business.

MM

 

[Giff]

I have had this when a smaller bearing, 12.7mm, overheated….just once and it disintegrated immediately. I think it was a cheap bearing on an expensive cutter.Never had any trouble since replacing them.Wealden are excellent, also Infinity are very good as well. http://www.infinitytools.co.uk/router-bit-bearings/

 

[Eric The Viking]

I'd experiment with speed, too.

Obviously there's always a best speed(!), but for years the only router I had was single speed (fast). Once I did get a vari-speed one I always tended to set it too fast, sometimes by quite a lot. It's only relatively recently that I tried dialling it down properly (i.e. experimented rather than guessed) and discovered how far off I usually was.

I know dovetail bits generally aren't very wide (therefore should be high-ish speed), but you never know. It will vary with the wood you're using, too. It's also possible that you're hitting a particular resonance at top RPM, giving you excessive vibration (which in turn may be shaking the bearing a lot). If you nudge it lower, even just a little, you might get significantly better results, simply because you aren't then on the resonant frequency.

Have you checked the fit in the jig? I've got a Stots (which the Dakota is very similar to). At least one of the cutters I use with it has a very 'snug' fit - probably too tight really. Of course it needs to be tight, otherwise the joint will be rough instead, but it's a reason why there's more stress than usual on the bearing in that application. Apart from keeping both bearing and jig very clean and free of resin, I'm not sure what you can do about that though.

Will you report back on how well behaved your new bearings are? I've had good results from Wealden ones, but this is a tough job for any bearing, and so a good test.

Cheers,

E.

 

[JeremyB]

Thanks for all the advice. The new bearings arrived yesterday and I will hopefully have a chance to give it a go again on Monday.

I understand what you are saying about speed and resonance etc, so I will set the speed down a notch and see if that helps. I will keep you informed of progress.

 

[Spindle]

Hi

If the dust seal is becoming dislodged it means that the outer race is moving far to much with respect to the inner race - the bearing is extremely close to total failure - you did the correct thing in stopping immediately and replacing the bearing. Under no circumstance should the seal be refitted and operation continue.

Regards Mick

 

[JeremyB]

The new bearings have arrived and been fitted to the cutters. I have also turned down teh speed on teh router, which may help with vibration etc.

So far I have cut quite a few trial joints which all worked out well with no problems and I am now trying out all teh nuances of teh jig to get the best looking joints in proportion to timber widths etc.

Many thanks for all your help.

I will post a photo of my finished box in due course ( I don't want to rush these things) to show you how it all worked out.