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Isolate the bearing? Other terms?

2690 Views 9 Replies 8 Participants Last post by  Gilbear
I hear Bob and Rick refer to "isolating the bearing" and I have finally figured what they mean is make sure the work-piece is NOT in contact with the bearing, for that particular cut. Correct?
But the occasional reference to "being on the cutting side of the bit" has me stumped. Why would you NOT want to be on the cutting side of the bit?
I sometimes get confused. But hell.....I'm gettin' older ya know!
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Isolating the bearing is a practice used when using a bearing guided bit with the fence. All it means is setting up the fence so that it an the bearing are in exactly the same plane. This gives you the full cut of the bit, while using the much greater supporting area of the fence instead of the bearing on the bit as a guide.

Staying on the cutting side of the bit is a safety issue. If you are making an unbalanced cut, like a rabbet or another edge treatment, you want to make sure that the only portion of the bit that is engaging the work is the "cutting side". If you can look at your bit, and see the face of the carbide insert in the flute, that is the cutting side. If you see the back of the flute, that is not. Sounds simple enough, but if you try to take too big of a cut, you can get into an unsafe situation. Staying on the cutting side puts the force of the router bit back against your feeding pressure and up against the fence. If you get off the cutting side, the bit can climb cut and steer your stock where it wants to go. This can pull your stock or your hand feeding it through the router.

Hope this is an adequate definition, I'm sure others will be able to amplify.
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I believe isolating the bearing is actually just that. Use something straight to line up the fence and the bearing,then nudge (technical term) the fence,with a hammer,or not, so that the fence and the bearing are almost but not quite lined up. Hope this makes sense.

You always want to be on the cutting side of the bit. Technically both sides will cut but if your pushing into the moving cutter then your on the cutting side of the bit. The other side of the router bit is pulling the material away from you.

To isolate the bearing follow this link?
just one more term I can think of ,,, that you may hear some one use when talking about this situation,,, When you use the "Other side" of the bit to do your cutting,,, It is called "Climb Cutting".... There are times when you do use that in metal working,, but your workpiece is being held securely in a vise and not by just your hands,,, but even then,,, you can get into trouble,,,

So you should never do any "Climb cutting" when routering ! ...... Unless you actually like going to the doctors...
Hi: Birchwood, That is correct to isolate the bearing means to not have contact, and is usually done by taking some scrap or anything that is straight and passing it from the infeed side of the fence, to the outfeed side. It should be close to but not touching the bearing.
As to being on the cutting side of the bit, means that you are running the stock into the sharp edge of the bit, as opposed to trying to but stock through the bit in the same direction as the bit is turning. As far as your getting older I can't help on that one, since I'm just shy of 71. I've got my own problems on that score.
Regards.. Woodnut65
Okay you guys-thanks. I've been thinking about those terms for a couple months! I'm about to embark on my first "serious" project. I intend to go very slow. I am pursuing one of those 45 degree miter lock bits. Saw one on Ebay but time ran out. There are two sizes; to use 3/4" ply I'm assuming I would only need the smaller one. Correct? Sure looks like a neat idea to me. Thanks again.
If you can't wait for Ebay, and want to give one of these bits a try......

I've never tried them in plywood however. Good luck!
Have you ever cut a dado with a hand held router? If you happen to have a plywood bit, you would not have to worry about the "cutting side of the bit", as the dado matches the plywood's thickness. However, some places ie. In Canada where I live the plywood is in metric thickness (17mm or 19mm) and the standard router bits do not match this thickness. To overcome this, a well known woodworker Nick Engler, devised a "not quite so square custom base plate" that had a zero side, a side 1/16" closer, a side 1/8" closer, and finally a 3/16" closer cut. This allowed him to cut a dado to fit the plywood with 2 cuts of the router with a fixed clamped fence, simply by turning the router to the appropriate side of the base plate. To make a short story long, which side of the base plate you started (ie. the fartherest cut away from the fence with the second cut closer) allowed you to push the router away from you as you are on the cutting side of the bit. However, if you cut the first pass with shortest side of the base plate, then the second cut required you to start on the other side of your workpiece and move the router towards you, or you moved to other side of the workpiece and pushed toward where you started, other wise you would be on the "wrong side of the bit".
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Birchwood said:
I am pursuing one of those 45 degree miter lock bits. Saw one on Ebay but time ran out. There are two sizes; to use 3/4" ply I'm assuming I would only need the smaller one. Correct? Sure looks like a neat idea to me. Thanks again.
Not sure about other brands and sizes, but at least at MLCS the lock-miter bit to cut full 3/4" material is actualy their larger one - I'd check out what the manufacturer says before spending the bucks - they should spec what minimum and maximum thickness their bit will cut.
By the way, I've had nice results with plywood.
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