Router Bit Grabbing

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The second thing is you are climb cutting. I know you think you are going the right way but make sure that is the case. When you start getting shapes you really need to think which is the right way. With a table it is the left hand rule, lay you left hand on the table and point your thumb in the direction you are pushing the wood into the bit and the fingers point the direction you want to move the wood. So if the wood is between you and the bit you are pushing the wood back away from you and the feed is to from the right side going to the left side. If the bit is between you and the work piece it is just the opposite.


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Ed

And so the subject of 'climb cutting' appears again.

Once again a way to determine if 'climbing' has been provided. Like most other 'memory "tricks"' it makes an assumption not included in the 'trick'(which direction is the bit spinning[cw?/ccw?]).

IMHO The best way to determine if climb cutting is to visualize what would the workpiece do(direction of motion) if the cutter 'caught' on the workpiece and caused it to be 'thrown'.

If the workpiece is pulled into the cutter then you are climbing.

If the workpiece is pushed back(opposite to feed direction) by the cutter, then you are not(plowing, not climbing).

Consider the normal way the saw is used. The saw blade rotates from the rear of the table towards the front of the table at the top of the blade which protrudes through the table. The workpiece is feed from the front of the table. As the blade contacts the workpiece, it is tending to push the workpiece back against the direction of feed. The blade is cutting from the deepest portion of the cut towards the area the blade exits the workpiece. When through cutting the 'deepest' part of the cut is the top of the workpiece. You are plowing.!

If for some reason you find yourself feeding the workpiece from rear of the table towards the front, the blade contacts the workpiece at the bottom and cuts up into the workpiece. Thus the blade is pulling the workpiece into the cutter. You are climbing.!

In the case of the saw example, the workpiece will always be thrown towards the front of the table. In the case of plowing, it is thrown back against the direction of feed. In the case of climbing, it is thrown in the same direction as the feed. This is why climbing hazardous. It pulls the workpiece INTO the cutting blade.

The same conditions determine climb/plow regardless of what type of cutter/blade is being used.

The problem with most 'tricks' is they assume a relative position of a fence or other restraining device as well as the rotation direction of the cutter/blade. All are adequate as long as the application is consistent with the underlying assumptions. These 'tricks' are useful for those applications, but do not help one to understand the climb/plow difference.

[dusty]

I have spent more time looking for an answer to my recent ill experience with a router.

I have found something out-of-order but it is hard for me to conclude that this is what caused the problem I had with the bit grabbing.

I found that the pattern following bearing is very tight (difficult to turn the inner race while holding the outer race firm).

My crisis is over because the shelves have been installed in the laundry room but I am still anxious to come to a conclusion about what caused the problem to begin with. I realize that may never happen but I am still anxious.

[dusty]

mickyd, You asked what happened with the shaper.

I can tell you what the results were but, to this very day, I don't know exactly what happened.

I had been a Shopsmith owner for several years but it had been a couple years since I had used it much. I spent an extended period of time on a tour of duty overseas and had not used it for a while. It is likely that my absence from the shop environment had an adverse effect on my ability to use it safety.

I was attempting to do a task on the shaper when suddenly I felt a severe pain in my left hand and was loosing a lot of blood. I don't believe I got hit by the blade. I believe something broke loose, hit my left hand and nearly severed the middle finger

I was rushed to the ER without getting a good look around and when I got back to the shop I found that my now son-in-law had already cleaned up the crime scene and destroyed all traces of real evidence. I can not tell you anything certain about the fence, hold downs, push blocks, speed settings -- nothing.

I do know that if it had not been for a very good ortho surgeon being on duty that day - I would likely be four fingered. I was real lucky. This is especially true because ortho does not usually due scheduled time in an ER.

[mickyd]

Well dusty, I have to admit that surely made me cringe!!! You were very fortunate.