As most have said, CLAMP the work piece down. Trying to hold the piece is just plain stupid, a good way to end up in the hospital, and a sign of someone who is pretty clueless about power tools.
Go slow and easy and back off periodically and clear out the shavings. You also want your drill press running as slow as possible; most of the fly cutters I've seen suggest no higher than a speed that's too low for some drill presses.
-Kevin
Bulkheads are harder to cut because you don't have the pilot drill to hold the center. And 29mm is rather small for a fly cutter.
But I'll bet you had to reverse the bit, and flipped it 180 degrees instead of 90 degrees. The pointy end must lead, with the tip on the side you want the good edge on.
And clamp the work down solid enough that it can't move. It may take 3-4 clamps to do this, especially with the pilot drill removed.
Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!
Ok, so seems my problems are not enough clamp (2 used need more for smaller stuff) and definitely speed to fast. You are correct turned the cutter 180deg, but it is a double edged cutter. Thanks Guys.
John.
Well "Tech Jerry", if you have any practical knowledge and experience with rotating machinery, such as a drill press and fly cutter, you should know that gloves are a no-nooo and "ASSUME" can get you hurt.
Fred
Hey! I resemble that remark... :-)
cp
The pilot hole from the fly cutter or hole say allows very accurate reallignment when flipping to the second side to complete the cut. It also allows accurate reallignment for the second hole to cut the ID.
Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!
But Bob, the question that was posed was - why not do the ID first, and then the OD? Doing the ID first means you effectively lose the pilot hole, and so run the risk of finishing the cut off-true.
Not if the outer waste piece is solidly clamped to the backing piece...
-dave w
Yes, I *know* that. In the post that started this, I specifically stated that...
"If you use the cut-halfway-and-flip method, you run the risk of losing your center-point - resulting in an off-center hole."
According to Len Lekx :
The "sacrificial chunk" I refer to _is_ the piece _under_ the material I'm cutting the CR in. If I'm drilling through a piece of wood on the DP, I always have a scrap under the workpiece. The scrap has the pilot hole.
Tho, since I don't move the clamps, the pilot hole really isn't necessary. Since I only clamp once, I can do without the pilot drill altogether (altho, the cuts are a little smoother).
I don't do the cut-halfway-and-flip method because it takes too long and is potentially subject to misalignment. It's also entirely unnecessary. Unless the flycutter is too dull.
Ie: clamp, drill ID (no flip), readjust hole saw, drill OD - pilot hole is _still_ present in the scrap, and since I didn't touch the clamping, the pilot hole doesn't really matter anyway.
It will be discontinued.
Guess I'm backwards from everyone else. My fly-cutter won't clear the clamps easily, so I usually clamp the material firmly to the work table (with a scrap board underneath) in such a way that the clamps are clear of the cutter as it goes around. Then cut the inside diameter first. The part is still firmly clamped down, and the scrap below provides the pilot hole. Now I swap cutters and cut out the OD. (The stock never moves and my press is good enough that the pilot hole isn't really necessary.) My hands are never anywhere near the cutter. So far my rings are perfect. This method wouldn't allow turning the ring over mid-way through the cut, though, but I find that if I keep the cutter sharp it doesn't chew up the back side of the piece; this is helped by the scrap board below if the part is clamped tightly. I will also cut very slowly - my press will go down to about 240RPM so I set it on the lowest setting and then use a light pressure. It takes a while but the clean cut is worth the wait.
Once I cut out an off-center ring on purpose to produce an F104-like rocket. I still used the same method though. First the centers of both the ID and OD were marked on the material. The part was clamped down firmly. Then ID was cut out, the tool was swapped, the material moved to the new center and reclamped before cutting the OD. Worked fine.
I've cut rings from all sizes in plywood and basswood of various thicknesses using this same method.
If I want to cut more than one ring the same size (and I normally do), I will tack glue the raw material together in a stack and cut all of them at once. It's important to tack glue them together or the top one is likely to cause trouble when it separates from the stock.
I can see the logic in cutting out the OD first, but I have trouble hanging onto the part when cutting the ID then. The problem is the arm of the cutter getting too low and whacking the clamp as it goes 'round. I'm using clamps designed specifically for a drill press, a sort of funny looking cross between a big bolt and a vice-grip. Since I'm pretty fond of my fingers I normally try pretty hard to keep them away from the moving parts! :-)
Later!
Aha, I'm not alone! Chris has come to the same conclusions - cut the ID first.
Right, and if you are using quality tools the and a bit of care the center pilot isn't strictly necessary, though very helpful. The block of wood underneath is very necessary or your going to spend lots of time filing and honing that cutter! :-)
. . . snipping . . .
Wow, and I thought 240 was pretty slow! Cool!
. . . snipping . . .
I hate it when the cutter bar slips, it's usually just enough one way or the other to make it so that you can't really work it out and wind up cutting another set. I will usually "choke up" a bit (move the bar higher up in the holder) to help with this. Making sure the set screw is tight and cutting gently helps prevent this problem.
Have you noticed that forstner bits require a good bit of honing before you can use them when new? The Chinese made ones especially.
That's far worse than suggesting to wear gloves.
Jerry
Thank-you for all the great posts on this topic everyone.
Not if you have the whole piece clamped firmly (or screwed or glued) - by the waste material on the _outside_ of the finished ring - to the backing piece... that way you would always have firm support, and keep the pilot hole. If you cut the OD first, then you would have to clamp the resulting disk either by the part that will be the finished ring, or by the waste piece in the center, for the ID cut!
-dave w
I suggest everyone who posted to this thread purchase rings from commercial vendors and NOT make them themselves.
Jerry
Tim - in case you don't know it, to most people on rmr, this is an excellent endorsement of your method.
I suggest that Jerry gets bent and keeps his moronic suggestions to himself.
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