Help w/ T-slot router bit

I am using a T-slot router bit, with bearing guide. http://www.mlcswoodworking.com/shopsite_sc/store/html/smarthtml/pages/bt_keyhl.html#T-slot%20cutter%20Anchor
Carbide. In a router table using a 1.5HP Craftsman router. 1/4" (Due to my own screw-up, I damaged it and am waiting for the replacement.) Anyway, before that, as I started to push the material through (actually 3/4" CPVC bar) -- the piece I am routing is only about 12" long -- the bit really "bit" into the stock and started to pull it into itself. Because of the shape of the bit, the purpose, I cannot take multiple passes at different depth settings as is SOP with many bits. I had set the speed down to maybe 10K.
Questions: Any advice about using this bit? To keep the bit from pulling the stock in, would a lower or higher speed help? Thanks. -- Igor
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hl.html#T-slot%20cutter%20Anchor
You are feeding the stock from the wrong direction! What you did is called climb cutting. Used only in a few special cases. -- Jim in NC
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wrote:

I see the problem now. I didn't catch exactly what kind of cut you were doing.
As you are in the shop, if you were looking at the machine and seeing the bit, then the guide, you should be feeding from the right. The featherboard sounds good, but not so tight as to make the wood impossible to feed without with out being smooth.
It is a tough type of cut to do, and my only advise is to keep your hands anchored to the table, and use your fingers to feed a little at a time. That way, when it tries to take off on you, are better able to control the rapid movement.
I would set the speed as high as you can without burning the wood.
Good Luck -- Jim in NC -- Jim in NC
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Nothing. You've got it right. You could try using a saller outer bit (strait) to cut a groove to get some of the material out of the way. YOu might want to increase the speed. If you do that and keep the feed the same, you will be taking less per revelution.
Maybe this is my most embarrassing moment

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In the original, he mentioned a ball bearing guide on the bit. I took that to mean he was only using one side of the T.
See my other post. I got it figured out.:-) -- Jim in NC
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Whoops! Correction. As my eyes should tell me, _no_ bearing guide. (Thinking about a different slot cutter I have meant for edges.)
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wrote:

Yes, I mis-wrote about the bearing -- see my errata post.
Well, you win the prize. The final cut will actually be a little wider then the bit profile. I had planned to make a cut down the center with the bit and then two more cuts, one to either side. The unmentioned way that I damaged the bit was when I did the following: After the initial "pulling" problem, I figured I'd try making a few passes on the TS to cut out some material from the center. I then moved the fence _closer_ to the bit rather than away. The CPVC stock started to zoom, then jump, and then jam -- which led to the bending of the 1/4" shaft of the bit. Hooray! Fortunately, only damage (beyond embarrassment) was to the bit. Anyway, while the consensus is that part of the problem on the first cut into a solid piece of stock (no pre-cuts) is unavoidable perhaps, you guessed "the rest of the story".
Thanks to everyone of the comments. A key point is that faster might help. I think for the new bit I will start by using the TS for some clearing cuts and then use the bit cutting _towards_ the feather boards. Even then, the passes will cause the bit to contact both sides of the groove, but the greater contact will be towards the feather boards -- so, in theory, the push-back force should be greater than the pulling force.
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Thanks for admitting you were using the bit in a manner other than normal. For all the others, when both wings of a bit are in the work, one must, of necessity be "climb cutting."
Of course the other is cutting in the proper direction.

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I try to help you with your English. As defined, "admit" means to acknowledge. You acknowledged that the worst happened when using the bit other than as intended. I mentioned that even when used as intended, one side of this bit, and others which engage the wood with both cutters simultaneously _must_ be climb cutting. Other replies were somewhat obsessed with this, I merely wished to clarify that it is inevitable, not the result of carelessness. The other side is working against rotation.
Now, if you are going to use it in an other than normal mode, you must assume the "inside" router direction rather than the outside.
Sorry to hear your feathers are ruffled, but it's important for those who might not otherwise use the bit to realize that your bad experience was perhaps self-abetted. As was, it would seem, your morning disposition

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wrote:

hi skol. So all I say is, screw away.
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There is no reason to cut a relief slot before using a T-slot or any other bit as long as the bit is cutting on both sides of the bit. It's just like cutting dados. The problems associated with climb cutting happen when the bit is only cutting material on the side closest to the fence.
When you know you will be widening a cut, your first cut MUST be made closest to the fence.
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Other than it reduces cutter load, reduces heat, .makes it last longer, reduces clogging.

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I don't have those problems when I feed the material at the proper rate. I also feel that reducing the number of steps to do a task makes it go faster and be more enjoyable. Plus, it saves wear and tear on the saw and that expensive blade.
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The Amana 5/16" T-slot cutter I bought today at Berland's cost me $58. Thats reason enough to use my pitifully inexpensive straight bits to make relief cuts if it'll make my T-slot bit last a little longer.
Besides that, think of the quality of the resulting work. You will you get a better cut due to less hogging / kickback, and theres now two sides for the dust to evacuate. Make the relief cut.
The software said it ran under Windows 98/NT/2000, or better. So I installed it on Linux...

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Simple solution. . . . Do it they way that gets you the results you want while being safe and not destroying your tools.

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