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  #11  
Old 02-20-2018, 10:32 AM
zaret zaret is offline
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ron, this is very helpful. thanks for taking the time to write it up.

when you cut the 1/4", is the first pass with a downcut spiral to get through the top veneer? i find that a 1/4" downcut spiral is fantastic with the prefinished for dados and rabbets... the finished edge is incredible, even cross-grain.

thanks again,

--- dz



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Originally Posted by Rlee1972 View Post
Might I suggest a combination approach from what I was given by the likes of Campbell, Vickers, and another?

I factored in bit cost, time to cut the average sheet of 3/4, among the other variables in the cost of CNC, took a half sheet of 3/4 plywood, and ran 30+ 40" straight lines and lines with 90 degree turns I created in Aspire. I numbered each line and adjusted the speed and feed of each line in variable of 60 increases in speed with variable ramp in lengths, plunge in rates, smooth or spiral, etc, etc creating separate toolpaths for each line. It took aprox 2 hours to create this along with making the proper notations on my writing pad for each line to be run. The following morning, after running these, I had my answer for feed/speed. It was within the parameters given in a previous post already. However, there are those whom I have great respect for that are running speeds in high production environments cutting custom that are much higher than my 13k/350ipm. When I weighed bit life against the fact an additional 5 minutes on the table would not negatively impact my bottom line in regards to our process, I chose a quality cut with prolonged bit/spindle life. I repeated this process using a .375 mortise compression bit on 1/2" and 1/4" plywood. I was surprised to find there had to be adjustments made for each product when cut quality has to remain superior to all other consideration. On the 1/4", I have found we have to make two passes instead of the one pass we make on 1/2" & 3/4" plywood. I took some advice given on this forum and made the first shallow pass with an end mill and the 2nd pass with the .375 mortise compression. Once I made this change on the 1/4", we now cut out 45 parts on the 4x8 1/4" with no splintering of the veneer anywhere. While it takes a little longer, we never have a part refused from the customer due to splintered edges. Hope this helps!
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  #12  
Old 02-20-2018, 11:42 AM
Ger21 Ger21 is offline
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Originally Posted by zaret View Post
ok, how about this - what rate should i be running the cutter if i want to keep the spindle at 18k?
About 800-900ipm, which your machine is probably not capable of.
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  #13  
Old 02-20-2018, 02:29 PM
zaret zaret is offline
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Originally Posted by Ger21 View Post
About 800-900ipm, which your machine is probably not capable of.
yes - this is what i've learned from this thread, thanks to all of you. very informative. so, i'll slow down the spindle for sure, and probably keep my rate ~350, and maybe even test a bit more strategically as others have done.

thanks guys...

-- dz
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  #14  
Old 02-20-2018, 11:35 PM
Rlee1972 Rlee1972 is offline
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Quote:
Originally Posted by zaret View Post
ron, this is very helpful. thanks for taking the time to write it up.

when you cut the 1/4", is the first pass with a downcut spiral to get through the top veneer? i find that a 1/4" downcut spiral is fantastic with the prefinished for dados and rabbets... the finished edge is incredible, even cross-grain.

thanks again,

--- dz
Just glad and humbled to be able to begin to give back a little to a forum that has provided so much to me.

Yes. 1st pass is with a .25 end mill downcut 2 flute spiral
Like you stated, cut quality is exceptional.
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