Kind of OT, but Elninios pictures of the workpieces remind of one turd at work, he is a CNC miller and leaves that kind of finish on mold inserts and pockets and everything. Guess who gets to clean up those with hard handwork by files, stones and generous use of an angle grinder, with high hopes that the customer doesn't check/care for flatness...
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I Got That Wood Grain Pattern Again..............
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Originally posted by Norman Bain View PostHighpower in post #27 has a photo with a pair of parallels being attached to long blue bars. Not sure what they are; but do those bars just "hang out"? Not saying they cause the patterning in JoeLee's case but bars hanging out will add to the vibration.
Sometimes when I use large g-clamps to hold stuff I find draping a wet towel over the ends of the clamp screws reduces vibration.
Cheers,
Norman
JL...................
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Originally posted by ammcoman2 View PostI read somewhere that one should actually set the tram just a little off "perfect". And then let the low side do a trail cut.
Another item: I didn't notice in the posts if you have been locking the quill. After getting advice from a seasoned pro, I now always lock it and use the knee feed.
Geoff
JL................
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Okay when you are using power feed how do you make sure feedrate is constant?
My guess is you dont
The force required to move x axis along the slides will vary depending on weight distribution and wear patterns that would affect feedrate.
Slight variation in chipload will shift grooves ever so slightly to create the woodgrain patterns
From the patterns i observed through a microscope i can tell for sure the distance between those grooves was slightly varying and that must have led to those marks.
Again on cnc it only happens when spindle speed or feedrate is jumping up and down. Which happens rarely enough unless you are trying.Last edited by Zero_Divide; 05-24-2013, 08:52 PM.FSWizard - Free Online Speed and Feed Calculator
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Originally posted by Jaakko Fagerlund View PostKind of OT, but Elninios pictures of the workpieces remind of one turd at work, he is a CNC miller and leaves that kind of finish on mold inserts and pockets and everything. Guess who gets to clean up those with hard handwork by files, stones and generous use of an angle grinder, with high hopes that the customer doesn't check/care for flatness...
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Originally posted by Norman Bain View PostHighpower in post #27 has a photo with a pair of parallels being attached to long blue bars. Not sure what they are; but do those bars just "hang out"? Not saying they cause the patterning in JoeLee's case but bars hanging out will add to the vibration.
Sometimes when I use large g-clamps to hold stuff I find draping a wet towel over the ends of the clamp screws reduces vibration.
Cheers,
Norman
Zero D. I don't think you get to say that word on here...but now you have to leave it up so people know what im referring too...
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Originally posted by Norman Bain View PostHighpower in post #27 has a photo with a pair of parallels being attached to long blue bars. Not sure what they are;
Cheers,
Norman
http://www.kurtworkholding.com/acces...lel_keeper.php
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Originally posted by Zero_Divide View PostHead-maybe.
But powerfeed is just a simple motor that moves slower if higher resistance is encuntered.
Also because its gear driven it will have not smooth motion , but there will be jerks in the movement.
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Originally posted by Zero_Divide View PostOkay when you are using power feed how do you make sure feedrate is constant?
My guess is you dont
The force required to move x axis along the slides will vary depending on weight distribution and wear patterns that would affect feedrate.
Slight variation in chipload will shift grooves ever so slightly to create the woodgrain patterns
From the patterns i observed through a microscope i can tell for sure the distance between those grooves was slightly varying and that must have led to those marks.
Again on cnc it only happens when spindle speed or feedrate is jumping up and down. Which happens rarely enough unless you are trying.
JL.......................
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Originally posted by JoeLee View PostWell you don't but the power feed is more consistant than if you were cranking the table by hand, also how much chip load can there be when your taking .0005 per pass???? my guess is not much.
JL.......................
Powerfeed will give you slightest variations of tool advancemet that will give you a pattern, but will not be severe.enough to screw it up completely.
I dont have a better theory.FSWizard - Free Online Speed and Feed Calculator
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i had a similar thing going on with my mill/drill - i wrote it off to it being a less than rigid machine.
then my drawbar threads started to strip so a made a new drawbar - the problem went away.
after looking closely at the old drawbar it was obvious the threads were cut really crappy and were not straight or concentric.
i think tightening it put some uneven stresses on the spindle/collet and produced a "pattern"
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1200, thats interesting about the draw bar threads but I can't see how that would cause vibration as long as the taper is seated in the spindle.
I milled the same piece of alum. this morning using my 3" shell mill this time. I ripped it right down the center and got no pattern.
So............ why is it that the 2" shell mill produces the pattern and the 3" does not???? I tried different speeds and feed rates and still no pattern. I was also using the same type inserts in the 3".
JL....................
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