I keep running into an issue with spiral reamers that leave what appears to be rifling in anything (aluminum) that I ream.
changing speed and feed rates doesn't seem to matter. Dry or with cutting oil doesn't seem to matter either.
The straight reamers of the same size don't seem to have this problem.
What might be causing this, or how does one stop it?
Use straight reamers?
heh, yeah.
Is this "normal" behavior? I can't quite figure out how it leaves such distinct marks that appear to match the shape of the cutting flutes, unless it's somehow bouncing around backwards like when a shaft is in a worn bearing and it makes that horrible chatter. I've been following the drill 1/64th undersize tip.
Is he using pot-aluminum? Y'know, that mushy crap which won't drill worth a hoot? It sticks to the flutes of the drill bit and rips a hole wider in some areas. Maybe he just needs a better grade of aluminum.
It sounds as though the reamers are chattering. Are the spiral reamers "machine reamers", if not 0.017" might be a trifle too large a cut. General practice seems to be a cut of ~0.015 in a half inch hole for a machine reamer and from 0.001 - 0.113 for a hand reamer.
You mean 6063-T5(whatever)?
Correction from 0.001 - 0.003 :-)
I used to actually give a damn.
it's through hole. chip build up doesn't seem to be a problem. The rifling starts immediately.
yeah, it doesn't appear to be the cause. It will happen at any depth, be it 1/4 or an 1".
not this one at least.
it's 6061-t rod, and some other scraps that were laying around.
It's no imprinted as such, but it's just a rod about 6" long with spiral cutters about 1-1/2" long one one side. There's nothing to make it look like you'd use it with a hand or t-handle as a hand tool.
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How deeply are you reaming? Further than 1-1/2"?
Lloyd
just a half inch, or that's as fast as I've bothered with this one reamer.
3 jaw chuck in a tailstock.
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Then it sounds like, despite all care, it's not exactly perpendicular to the hole, or running slightly eccentric; Enough so that one area is cutting more aggressively than another -- and since they go all the way around the bore, I'm suspecting eccentric to the shaft.
Where did you get this reamer, and what is: 1) its diameter, and 2) its cost/provenance.
How are you driving it?
Lloyd
1) 0.250" x 6" 2) unknown, was new in packaging, chinese origin, fit and finish seem good.
it's being driven into the work by turning the crank on the lathe's tailstock. The lathe is a sherline, so everything is tiny.
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yeah... that's not all there is to "driven". Depth per rotation, etc....
ANYway... Even if you assume the reamer is perfect, there's little chance that the tailstock of a Sherline is either aligned in X OR parallel to the headstock. Because the straight reamers cut on their entire length all at once, that could be accommodated by them simply by BENDING the shank enough to get the reamer in alignment with the hole.
If the alignment and the reamer were perfect, a spiral reamer _would_ cut on all surfaces at once. But bend it a little, and it cuts preferentially on one "lobe" of an edge.
As others have said, I think you have an alignment problem.
LLoyd
"Lloyd E. Sponenburgh" fired this volley in news:XnsA2FBA07F299C7lloydspmindspringcom@216.168.3.70:
PS... 'bet you're holding it in a drill chuck, too. Yes?
(hint... It wouldn't be straight on your life... )
Lloyd
will have to try that rule trick.
shop dog has some great recipies by the way- I tried the apple cake.
I prefer using an indicator in the spindle, attached to a medium lengt rod so that it can be repositioned, lock the tailpiece and indicate the tail center at both the retracted and extended positions. This not only centers the quill but it also tells you whether the quill travel is parallel to the spindle bearing rotational axis (if it is not parallel then a drill might line up perfeftly but a reamer will be off-center because a reamer is typically longer than a drill)
Usually though I just chamfer a bit larger than the reamer and then single point bore a bit smaller than the reamer for a shallow distance, which eliminates the problem of reamer wobble on entry....generally works fine except in exceptionally soft materials since tailstiocks and reamers tend to flex fairly easily and so they'll tend to follow the hole if you at least given them a fighting chance.
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