Gallery, Projects and General > Oooops!
I screwed up using a slitting saw..
sparky961:
I find that mistakes are often much more instructive than success. Sure, they suck, but if everything always goes right you don't know where the edge of the envelope lies.
I'm sitting here staring at your picture, which is probably not enough to go on, but I keep looking at the arcs scratched beneath the slot. I'm thinking that there are only two ways this could have happened: 1) The pin turned (which you probably would have noticed and mentioned) or 2. when the catastrophic event occurred, the blade bent down and rubbed along the bottom for a while but since there's no postmortem photo of the blade I can only guess if it bent or shattered.
I know it's easy when stuff like this happens to "rip" the %$*@#& part out of the vice, whip it across the room and then sit there and almost cry when you've spent so many hours getting it to that point. However, two things I've learned (seems I'm on a "twos" kick tonight): 1) Leave it and walk away for a while. There may, in some cases, be a way to fix it if its still set up. At the least you can examine what went wrong with a clearer head after a little walk. 2) Make a couple parts to work with in the first place. Its usually only a few more minutes for each setup to run another part or two extra. But to start over from scratch each time something goes wrong is very time consuming. Material is cheap, time isn't - even hobby time, which most people consider "free".... it's still your time and its finite. Make the most of it.
I tend to favour the theory that the saw grabbed your table and moved it, if it wasn't locked. In the picture I'd say the right table lock is not locked, but the left one is obscured by the vice handle. It doesn't take much, and the forces would have been in the correct directions to do so. The likelihood increases if your machine has a lot of backlash and you were on the "wrong" side of it to start with (been there, done that... got the T-shirt). If the pin had pulled out of the collet the result would be similar, but that seems less likely than everything else. If, however, you're really squeezing down on a 5C collet, that likelihood goes back up exponentially. They don't have much effective range. It could also explain the pin rotating.
Just think though, anything you weren't quite happy with the first time around you get another crack at. You've also done the setups and found the tools so it should go much quicker this time.
Yet another thought.... if you have it in a collet block why are you moving the cutter around to the opposite side? Just flip the block 180 degrees.
Brian (Sparky)
(Edit: Just re-read your post and saw that you did mention indexing the pin instead. Glad you saw that one already.)
PeterE:
My mind goes as follows; Why have a pin in the "tube" when slitting? It might have been so that some swarf got stuck between the inner wall of the tube and the supporting pin in the second run and it pinched the saw, and consequently broke the blade. Without the pin it may have worked nicely. :scratch:
/Peter
mcostello:
I make a commercial part for a customer from 303 SS. The slot is .050 wide and 3/8" deep through a wall of SS tubing. Coolant was not heavy duty enough. I go with a mister using cutting oil, it blows the chips off and is the best lubricant I can think of. I still lost the occasional saw blade, went with a small horizontal mill with an arbor and have not lost a blade since.
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