Hi Vjeko

You can't add a bearing to one but you can add a bearing to the shank of the bit that will act the same way almost ..

The bit needs a place to hold the bearing and a shoulder to run on..

========

 

Bob,
You mixed me up with the negative/positive answer / what
is the difference between the normal and top bearing bits and is
my aim of adding a top bearing to a normal bit pointless/should
I just order a top bearing bit ?

 

Hi vjeko

Sorry, in short you can't add a bearing..

" difference between the normal and top bearing bits"
They always have a very small ID ,they use a 2 or 3 or 4mm screw to hold them in place.

==========

 

Hi Bob,
now I understand why I didn't understand you
There seems to be a confusion on what "top bearing"
means - at least I see some people calling
the bits you depict as top bearing (same ones I have),
while others call the bits with the bearing near
the collet/on the shank "top bearing".

I was talking about the ones where the bearing goes
on the shank/near the collet -(at least from googling
I see it's the easiest solution to my installation of the
router plate in the router table).

 

Hi

The bearing on the bit is not needed most of the time it's just a fence ,in the round you could say..you can add any size bearing to the shank of the router bit,,,,I have many over size ones just for that type of job..

Not to fill your head up with more junk you don't need but some come with both types

Top & Bottom Bearing
Flush Trim/Pattern Bits

http://www.mlcswoodworking.com/shopsite_sc/store/html/smarthtml/pages/bt_flush.html


=====

 

OK, thanks Bob !
Any tips on what to ask for if I go to the local
SKF or whatever seller - shank 8mm, 10mm, 12mm ,1/2",
max rotations anything else ? - and where can I get the
part which looks like a depth stop (which presumably holds
the bearing down or is it up) ?

 

Hi

" depth stop " = ??
You can get the lock rings from MLCS or just about any bearing outlet store.

MLCS Woodworking Adaptor Bushings and Ball Bearing Guides


====

 

I have tried both kind of trimming bits...
where the bearing is "on top" (near the collet) and bits that have bearing at the bottom (the end of the bit).

after using, I prefer ones with bearings at the bottom.

The ones I have with bearings on top, if you look at the bit closely,
you have the bit itself, then the bearing on top, then another ring (with a lock screw) to hold the bearing in place.

my experience is... after some spinning, that top lock ring will come loose, and that bearing will start to slide up and down, making your cut not perfect.

So, if you want to use a bit with bearing on top, you should use straight bit, and then use those rings that locks on the router plate.

that's my limited experiences.... hope it helps.

 

You're right there, Henry... shank-mounted bearing retainers should be checked before every use. I use them for my Katie Jig dovetails (amongst other uses) and check 'em each time... and sometimes they aren't as tight as they should be. I need to get some removable lock-tite type stuff, but until then I keep checking... and tightening! :>

 

Vejko, I'm not sure what size collet you have on your router, but up here in Zagreb at the flee market(hrelić) you can find a lot of bearings that are perfect for 8mm router bits( something makes me think they are from rollerblades). I find that if you want to keep the bearing on the bit permanently, you can rough up the shank with some sand paper and then tap the bit down. Seems to hold well and I guess you could always use some loctite to be sure.

 

Hi gav,
As it's difficult to get everything in metric and metric/imperial is not
relevant in some situations, I've covered all the bases with 1/4",1/2",6mm,8mm,10mm and 12mm (OK, I went overboard - but I can use any bit I like especially if the price and function are right . I guess you're right about the bearings being roller bearings - unfortunately I'm a couple of hundred km away from Zagreb. In the meantime I have contacted bearing distributors to get their feedback - as soon as I hear what
they have to say I will post it here so there's no confusion / we're on the right path
when buying them.

 

My experience of getting bearings from a bearing factor in Porec was that they could get most sizes within 24hrs, but that the imperial sizes were a lot dearer than the metric ones as they were non preferred sizes.

Cheers

Peter