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Author Topic: Problems threading on the lathe  (Read 330195 times)

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Re: Problems threading on the lathe
« Reply #60 on: February 26, 2009, 09:41:20 PM »
Just a thought..(rare for me). ::)
The fellows with the X walking problem stated that the DRO reflected the move as well....
I can understand noise creating a pulse to the driver but would it show up in the DRO ?
Thanks,
RC
Re: Problems threading on the lathe
« Reply #61 on: February 26, 2009, 10:18:30 PM »
spindle slows maybe >1 rpm.software says "holy crap I'm lost".
The control then goes looking for wear it should be.I think a software solution might be.
If reference pulse signal varies by (small value) then retract x from thread imidiatly
return tool to start position and carry on at last cut value.
Re: Problems threading on the lathe
« Reply #62 on: February 26, 2009, 10:49:28 PM »
Ok, I went out to the shop tonight, I had too many thoughts going thru my head with all of the helpfull suggestions recieved here tonight.  I have lots to report, I will Divide it up into a couple of posts.  First for the code that I used.

G-76, I guess that it didn't copy onto my thumb drive in the garage, I will have to get it tomorrow...

Long code:

(Taper = 0)
(Infeed Angle = 15)
(Total_Depth = 0.125)
(StartZ = 0.1)
(EndZ = -0.75)
(Seq = 0 )
(Min_Decrement = 0.0001 )
(Dia Mode )
G0 X0.525 Z0.1
G0 X0.5
(Decrement = 0.014 pass 1)
G01 Z0.1
G32 X0.486 Z0.0981 F0.077
G32 X0.486 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0058 pass 2)
G01 Z0.1
G32 X0.4802 Z0.0973 F0.077
G32 X0.4802 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0044 pass 3)
G01 Z0.1
G32 X0.4758 Z0.0967 F0.077
G32 X0.4758 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0038 pass 4)
G01 Z0.1
G32 X0.472 Z0.0962 F0.077
G32 X0.472 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0033 pass 5)
G01 Z0.1
G32 X0.4687 Z0.0958 F0.077
G32 X0.4687 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.003 pass 6)
G01 Z0.1
G32 X0.4657 Z0.0954 F0.077
G32 X0.4657 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0027 pass 7)
G01 Z0.1
G32 X0.463 Z0.095 F0.077
G32 X0.463 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0026 pass 8)
G01 Z0.1
G32 X0.4604 Z0.0947 F0.077
G32 X0.4604 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0024 pass 9)
G01 Z0.1
G32 X0.458 Z0.0944 F0.077
G32 X0.458 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0023 pass 10)
G01 Z0.1
G32 X0.4557 Z0.0941 F0.077
G32 X0.4557 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0022 pass 11)
G01 Z0.1
G32 X0.4536 Z0.0938 F0.077
G32 X0.4536 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0021 pass 12)
G01 Z0.1
G32 X0.4515 Z0.0935 F0.077
G32 X0.4515 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.002 pass 13)
G01 Z0.1
G32 X0.4495 Z0.0932 F0.077
G32 X0.4495 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0019 pass 14)
G01 Z0.1
G32 X0.4476 Z0.0929 F0.077
G32 X0.4476 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0018 pass 15)
G01 Z0.1
G32 X0.4458 Z0.0927 F0.077
G32 X0.4458 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0018 pass 16)
G01 Z0.1
G32 X0.444 Z0.0925 F0.077
G32 X0.444 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0017 pass 17)
G01 Z0.1
G32 X0.4423 Z0.0923 F0.077
G32 X0.4423 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0017 pass 18)
G01 Z0.1
G32 X0.4406 Z0.0921 F0.077
G32 X0.4406 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0016 pass 19)
G01 Z0.1
G32 X0.439 Z0.0919 F0.077
G32 X0.439 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0016 pass 20)
G01 Z0.1
G32 X0.4374 Z0.0917 F0.077
G32 X0.4374 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0015 pass 21)
G01 Z0.1
G32 X0.4358 Z0.0915 F0.077
G32 X0.4358 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0015 pass 22)
G01 Z0.1
G32 X0.4343 Z0.0913 F0.077
G32 X0.4343 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0015 pass 23)
G01 Z0.1
G32 X0.4329 Z0.0911 F0.077
G32 X0.4329 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0014 pass 24)
G01 Z0.1
G32 X0.4314 Z0.0909 F0.077
G32 X0.4314 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0014 pass 25)
G01 Z0.1
G32 X0.43 Z0.0907 F0.077
G32 X0.43 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0014 pass 26)
G01 Z0.1
G32 X0.4286 Z0.0905 F0.077
G32 X0.4286 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0014 pass 27)
G01 Z0.1
G32 X0.4273 Z0.0903 F0.077
G32 X0.4273 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0013 pass 28)
G01 Z0.1
G32 X0.4259 Z0.0901 F0.077
G32 X0.4259 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0013 pass 29)
G01 Z0.1
G32 X0.4246 Z0.0899 F0.077
G32 X0.4246 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0013 pass 30)
G01 Z0.1
G32 X0.4233 Z0.0897 F0.077
G32 X0.4233 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0013 pass 31)
G01 Z0.1
G32 X0.4221 Z0.0895 F0.077
G32 X0.4221 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0012 pass 32)
G01 Z0.1
G32 X0.4208 Z0.0893 F0.077
G32 X0.4208 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0012 pass 33)
G01 Z0.1
G32 X0.4196 Z0.0891 F0.077
G32 X0.4196 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0012 pass 34)
G01 Z0.1
G32 X0.4184 Z0.0889 F0.077
G32 X0.4184 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0012 pass 35)
G01 Z0.1
G32 X0.4172 Z0.0887 F0.077
G32 X0.4172 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0012 pass 36)
G01 Z0.1
G32 X0.416 Z0.0885 F0.077
G32 X0.416 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0012 pass 37)
G01 Z0.1
G32 X0.4148 Z0.0883 F0.077
G32 X0.4148 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0011 pass 38)
G01 Z0.1
G32 X0.4137 Z0.0881 F0.077
G32 X0.4137 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0011 pass 39)
G01 Z0.1
G32 X0.4126 Z0.0879 F0.077
G32 X0.4126 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0011 pass 40)
G01 Z0.1
G32 X0.4115 Z0.0878 F0.077
G32 X0.4115 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0011 pass 41)
G01 Z0.1
G32 X0.4104 Z0.0877 F0.077
G32 X0.4104 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0011 pass 42)
G01 Z0.1
G32 X0.4093 Z0.0876 F0.077
G32 X0.4093 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0011 pass 43)
G01 Z0.1
G32 X0.4082 Z0.0875 F0.077
G32 X0.4082 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0011 pass 44)
G01 Z0.1
G32 X0.4071 Z0.0874 F0.077
G32 X0.4071 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.001 pass 45)
G01 Z0.1
G32 X0.4061 Z0.0873 F0.077
G32 X0.4061 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.001 pass 46)
G01 Z0.1
G32 X0.405 Z0.0872 F0.077
G32 X0.405 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.001 pass 47)
G01 Z0.1
G32 X0.404 Z0.0871 F0.077
G32 X0.404 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.001 pass 48)
G01 Z0.1
G32 X0.403 Z0.087 F0.077
G32 X0.403 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.001 pass 49)
G01 Z0.1
G32 X0.402 Z0.0869 F0.077
G32 X0.402 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.001 pass 50)
G01 Z0.1
G32 X0.401 Z0.0868 F0.077
G32 X0.401 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.001 pass 51)
G01 Z0.1
G32 X0.4 Z0.0867 F0.077
G32 X0.4 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.001 pass 52)
G01 Z0.1
G32 X0.399 Z0.0866 F0.077
G32 X0.399 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.001 pass 53)
G01 Z0.1
G32 X0.3981 Z0.0865 F0.077
G32 X0.3981 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.001 pass 54)
G01 Z0.1
G32 X0.3971 Z0.0864 F0.077
G32 X0.3971 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0009 pass 55)
G01 Z0.1
G32 X0.3962 Z0.0863 F0.077
G32 X0.3962 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0009 pass 56)
G01 Z0.1
G32 X0.3952 Z0.0862 F0.077
G32 X0.3952 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0009 pass 57)
G01 Z0.1
G32 X0.3943 Z0.0861 F0.077
G32 X0.3943 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0009 pass 58)
G01 Z0.1
G32 X0.3934 Z0.086 F0.077
G32 X0.3934 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0009 pass 59)
G01 Z0.1
G32 X0.3925 Z0.0859 F0.077
G32 X0.3925 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0009 pass 60)
G01 Z0.1
G32 X0.3916 Z0.0858 F0.077
G32 X0.3916 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0009 pass 61)
G01 Z0.1
G32 X0.3907 Z0.0857 F0.077
G32 X0.3907 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0009 pass 62)
G01 Z0.1
G32 X0.3898 Z0.0856 F0.077
G32 X0.3898 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0009 pass 63)
G01 Z0.1
G32 X0.3889 Z0.0855 F0.077
G32 X0.3889 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0009 pass 64)
G01 Z0.1
G32 X0.388 Z0.0854 F0.077
G32 X0.388 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0009 pass 65)
G01 Z0.1
G32 X0.3871 Z0.0853 F0.077
G32 X0.3871 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0009 pass 66)
G01 Z0.1
G32 X0.3863 Z0.0852 F0.077
G32 X0.3863 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0009 pass 67)
G01 Z0.1
G32 X0.3854 Z0.0851 F0.077
G32 X0.3854 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0009 pass 68)
G01 Z0.1
G32 X0.3846 Z0.085 F0.077
G32 X0.3846 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0008 pass 69)
G01 Z0.1
G32 X0.3837 Z0.0849 F0.077
G32 X0.3837 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0008 pass 70)
G01 Z0.1
G32 X0.3829 Z0.0848 F0.077
G32 X0.3829 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0008 pass 71)
G01 Z0.1
G32 X0.382 Z0.0847 F0.077
G32 X0.382 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0008 pass 72)
G01 Z0.1
G32 X0.3812 Z0.0846 F0.077
G32 X0.3812 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0008 pass 73)
G01 Z0.1
G32 X0.3804 Z0.0845 F0.077
G32 X0.3804 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0008 pass 74)
G01 Z0.1
G32 X0.3796 Z0.0844 F0.077
G32 X0.3796 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0008 pass 75)
G01 Z0.1
G32 X0.3788 Z0.0843 F0.077
G32 X0.3788 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0008 pass 76)
G01 Z0.1
G32 X0.378 Z0.0842 F0.077
G32 X0.378 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0008 pass 77)
G01 Z0.1
G32 X0.3772 Z0.0841 F0.077
G32 X0.3772 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0008 pass 78)
G01 Z0.1
G32 X0.3764 Z0.084 F0.077
G32 X0.3764 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Decrement = 0.0008 pass 79)
G01 Z0.1
G32 X0.3756 Z0.0839 F0.077
G32 X0.3756 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
(Last Pass ID_OD = 1)
(Decrement = 0.0005 pass 80)
G01 Z0.1
G32 X0.3751 Z0.0838 F0.077
G32 X0.3751 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
( Last pass at depth of 0.0001)
G01 Z0.1
G32 X0.375 Z0.0838 F0.077
G32 X0.375 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
( Spring pass number 1)
G01 Z0.1
G32 X0.375 Z0.0838 F0.077
G32 X0.375 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
( Spring pass number 2)
G01 Z0.1
G32 X0.375 Z0.0838 F0.077
G32 X0.375 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
( Spring pass number 3)
G01 Z0.1
G32 X0.375 Z0.0838 F0.077
G32 X0.375 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
( Spring pass number 4)
G01 Z0.1
G32 X0.375 Z0.0838 F0.077
G32 X0.375 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
( Spring pass number 5)
G01 Z0.1
G32 X0.375 Z0.0838 F0.077
G32 X0.375 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
( Spring pass number 6)
G01 Z0.1
G32 X0.375 Z0.0838 F0.077
G32 X0.375 Z-0.75 F0.077
G01 X0.525 Z-0.75 F0.077
G00 X0.525 Z0.1
G00 X0.5
G00 X0.525 Z0.1

Re: Problems threading on the lathe
« Reply #63 on: February 26, 2009, 10:55:06 PM »
Ok both turned out like ka ka, but here are some of the specs that I used.

.500 od
.375 Minor dia
.077 pitch for 13tpi
.014 first pass
No taper, No chamfer
400RPM which made for travel of 30.8UPM
81 passes and 6 spring passes


Here is the first thread cut using the G76 code
Re: Problems threading on the lathe
« Reply #64 on: February 26, 2009, 11:03:58 PM »
Here is another fo the first thread cut using the G76 code which shows some very interesting wavy shape to the threadform along with the tool that I am using to cut the threads.  The thread cut fine for about the first three or four passes, but then it began to slow down the spindle and the fun began.  I paid very close attention to what happened and realized that it was cutting every other pass in the air, then cutting tha alternating passes at what seemed to be twice the normal depth.  Here is the really interesting part--Sometimes when actually cutting every other pass it would cut straight with no X movement, and sometimes it would cut them at a taper with an x movement thrown in along with the Z movement.  As you can see the thread is not correct, but it does fit my cheapo thread gauge perfectly!


More to follow, time to put the kids to bed....
Re: Problems threading on the lathe
« Reply #65 on: February 26, 2009, 11:40:30 PM »
OK now for the second thread that I cut with the long code posted a few posts back.  All of the specs are the same, I saved them in the wizard, then changed the macro using the instructions kindly provided earlier and re posted.  This thread also didn't turn out, but in a different way.  The first couple of passes turned out allright, then the spindle slowed about 25 rpm and things went south.  This time it was also interesting to watch as a allmost magical pattern appeared.  It would cut a pass, slow down, then the next pass it would cut in the air completely outside of the thread.  Then the next pass would be cut at the commanded depth(I had a chance to compare the DRO to the code several times)  but since the pass before didn't remove any material it's "effective" depth was too great which resulted in another reduction of spindle speed followed by another air cut and on and on.  Then about the last 30 cuts it began to again throw in a little taper as can be seen in the finished thread pictured below.  I think that you can see that the thread is cut deeper towards the end of the thread than it is at the beginning. 

Here are some things that I observed

I was amazed that no matter how wrong things seemed to go the cutter always followed the correct pitch, and never crashed into the workpiece, this is pretty impressive to me and shows that the software is in fact doing a very nice job of correcting the Z feedrate on the fly.

I also noticed something interesting while watching the turn diag. screen.  I had the spindle turning at 400-405 rpm, and the greatest deviation that I ever had was 39 RPM, but the box that shows by what percentage the speed was off by showed a max of 39 percent.  I think that 39 RPM is approx 10 percent of 400 RPM, and it leaves me wondering if Mach really thinks that the speed deviates by 39 percent, or if the box is simply mislabeled with a % sign?

It may turn out that I need to be able to controll the RPM to a greater degree than is presently possible, with my current spindle motor?

I think that tomorrow maybee I should try to cut the same thread in lots(maybee several hundred) passes and see what happens then.

Let me know if all of my ramblings have made any sense, and possibly inspired an idea or two as to what I should try next.

Thanks

Offline Hood

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Re: Problems threading on the lathe
« Reply #66 on: February 27, 2009, 02:31:08 PM »
So even using G32 you are getting the taper cuts and the X dro is showing that taper?
Hood
Re: Problems threading on the lathe
« Reply #67 on: February 27, 2009, 03:44:55 PM »
Hood, Yes the taper happens no matter how te code is generated.  Later today I am going to try to cut a thread in about 200 passes and see what happens.  I will report back tonight.
Re: Problems threading on the lathe
« Reply #68 on: February 27, 2009, 07:13:15 PM »
I did some more testing today with similar results.  I also took a video of the process which I think will help to illustrate the unusual movements that I and others have been describing.  Is is possible in inbed video here, or do I just need to post a link to the video on youtube.  let me know.  Thanks.

Offline Hood

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Re: Problems threading on the lathe
« Reply #69 on: February 27, 2009, 07:17:47 PM »
Yes you can embed :)
Hood