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Post by davidtu on Jul 21, 2018 21:40:09 GMT -5
Newbie--first use.
I am doing a 2D Profile cut on 2.5" actual thickness douglas fir using a CMT 191.507.11 bit. Its operating at 250herz or 15000 RPM, max 16000. This is a 2 edge upcut spiral bit. 1/2" shank, 1/2" D, 2" CL, 4" height overall. Feed rate 50 in/min, plunge 30 in/min. Its doing 7 passes .0371" per pass.
It wont let me upload any files. Any help much appreciated.
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Post by stevem on Jul 21, 2018 22:05:41 GMT -5
What do you mean you can't upload files? The size of the bit has nothing to do with that. What is the machine doing? What message are you getting??
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Post by ricphoto on Jul 21, 2018 22:24:38 GMT -5
Not much to go on but there's been lots of talk about faulty controllers lately...check those threads...you'll probably end up calling and getting a replacement
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Post by gerry on Jul 22, 2018 2:21:42 GMT -5
he's talking about posting more examples and photos. The forum boards will not allow any uploads. They say the board is full.
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Post by Gary Campbell on Jul 22, 2018 7:35:42 GMT -5
David... Your math is off a bit. Your pass depth is .371 not .0371. Doug Fir is a hard material that has even harder than normal areas in it. You are most likely trying to cut more aggressively with a large bit than the machine can handle. Reduce your pass depth to around an eighth and experiment from there
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Post by Deleted on Jul 22, 2018 11:28:06 GMT -5
You say the bit is slipping down, do you mean it's sliding out of the collet or that the Z axis is actually moving more steps than it's supposed to? For the former you should clean the spindle, collet and bit, for the later take a less aggressive cut as the motor doesn't have enough torque to overcome the force of the up cut bit pulling the Z axis down and gravity at the same time. An alternative to the later is to use a straight or down cut but as they don't pull the workpiece and spindle closer together.
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Post by redwood on Jul 22, 2018 11:28:38 GMT -5
It could also be your collet is not locked down into the collet nut. It should sort of snap in and out of the collet nut.
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Post by davidtu on Jul 23, 2018 13:26:14 GMT -5
You say the bit is slipping down, do you mean it's sliding out of the collet or that the Z axis is actually moving more steps than it's supposed to? For the former you should clean the spindle, collet and bit, for the later take a less aggressive cut as the motor doesn't have enough torque to overcome the force of the up cut bit pulling the Z axis down and gravity at the same time. An alternative to the later is to use a straight or down cut but as they don't pull the workpiece and spindle closer together. It appears that the bit was actually moving down within the collet. I have read elsewhere that spiral upcuts will tend to pull out and to make sure its really tight. I am making it *really* tight already. Btw the machine and the bit are both brand new, couldn't have any buildup of anything yet. I have marked the bit so I can see if it will slip as I go forward. I have also seen elsewhere that a loose coupling in the Z axis can cause problems.... though it seems like my problem was the bit moving not the machine losing track where it was... but I have also gone ahead and tightened the coupling--again... super newbie here so I'll ask... this is just the single allen screw correct?
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Post by Deleted on Jul 24, 2018 14:01:57 GMT -5
Any new parts are especially suspect and must be cleaned. They likely have metal dust from griding during manufacturing and oil to keep them from rusting on the shelf and before you get your hands on them. Clean everything well and you'll likely have a much better grip. As you're using them you will also get dust that needs occasional cleaning. This is a nice kit for cleaning: www.precisebits.com/products/chemicals/colletcare.aspBut you can use degreasers/solvents that do not leave a residue such as mineral spirits, naphtha, denatured alcohol and Q-tip but do not use isopropyl alcohol as it contains water. Keep in mind that some Q-tip types contain small amounts of clay (ones not specified for optical use) and you don't want ones that shed fibers either.
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