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Kevin Perez
12-18-2020, 11:22 AM
I have a 1/4" shank Rockler three wing slot cutting bit that cuts a 1/2" deep with the 7/8" bearing that came with it. Does anyone know offhand what size bearing it takes and whether the bearing can be replaced with a larger one? I'd like to have a 3/8" depth of cut and be able to use it without a fence on a curved piece of wood. Please let me know, thanks!

Ronald Blue
12-18-2020, 12:22 PM
I have no idea what the bearing size is but make a sleeve to slip over it. If you add a sleeve that's 1/8" thick it will reduce the depth of cut by 1/8". Here's an option. Food for thought.
mcmaster.com/bushings/system-of-measurement~inch/for-shaft-diameter~7-8/for-housing-id~1/plain-bearing-type~sleeve/

Bill Dufour
12-18-2020, 2:37 PM
what is the bearing number? At the rpm probably shielded not sealed.
Bil lD

Bill Dufour
12-18-2020, 3:09 PM
Just measure the bore and thickness. I assume the bore is some nice whole number of mm's. I assume the 7/8 is really 22mm? since you need to reduce cut depth by 1/8". I think you need 3mm more radius so 6mm more diameter so 28mm bearing? someone please check my math
Bill D

https://www.highlandwoodworking.com/router-bit-bearing-guide.aspx

Kevin Perez
12-18-2020, 3:56 PM
It's a 608Z, which is a 22mm OD, 8mm ID, 7mm tall shielded bearing. Bill, you are right on the math. I'd need a 28mm replacement.

Bill Dufour
12-18-2020, 4:01 PM
NTN or SKF have the best interchange info on line.
Bill D.

https://bearingfinder.ntnamericas.com/viewitems/deep-groove-ball-bearings/single-row-radial-ball-bearings

Bill Dufour
12-18-2020, 9:06 PM
I have a feeling you will have to use a bushing to reduce the inner bore down to 8mm.
Bill D

John C Bush
12-18-2020, 9:45 PM
I've never used a slot cutter but I do have a "kit" of various sized bearings that fit a rabbiting bit to change depth of cut. Small hex screw and retaining washer that secure them to the bottom of the bit.
Not sure if applicable to your cutter but Rockler, Infinity, and other catalogues list them.

Ronald Blue
12-18-2020, 10:30 PM
I have a feeling you will have to use a bushing to reduce the inner bore down to 8mm.
Bill D

That's my assessment. There isn't a 28 mm OD bearing with and 8 mm ID that I see. Biggest OD is 24 mm. Look for metric bushings instead.