C-Axis Cut Chatter

[Chaotic5555]

Hey Guys, 

Hope everyone is having a great holiday season (Merry Christmas Eve Eve).  

I'm having some issues with a C-Axis cut on our machine  right now.  Its got a very rough surface finish and seems to be very chattery.  I haven't had this issue in Mastercam before and was just wondering if some of the more experienced guys out there had some tips they could give me on reducing it.  

Here's a copy of the C-Axis portion of the Code.  I added a multi-pass to try and reduce it by creating a finish pass but still seems to have the same issues.  We've also changed tooling and reduced the end mill size several times.  

N5 G0 G59 X0 Z0 
T1111 
(TOOL - 11 OFFSET - 11) 
( 3/8 FLAT ENDMILL) 
M69 
M47 
G0 C35.178 
M46 
G97 S1250 M03 
G0 G54 Z.044 
X1.5544 
Z-.106 
G98 G1 Z-.206 F3. 
X1.4919 C31.615 F188.4147 
X1.4367 C27.833 F203.8597 
X1.389 C23.841 F218.9762 
X1.3491 C19.656 F233.213 
X1.3172 C15.3 F245.9516 
X1.2934 C10.806 F256.5552 
X1.278 C6.212 F264.4336 
X1.271 C1.562 F269.1147 
X1.2724 C-3.097 F270.3099 
X1.2821 C-7.718 F267.9557 
X1.3001 C-12.256 F262.2217 
X1.3262 C-16.67 F253.4836 
X1.3602 C-20.927 F242.2677 
X1.4019 C-25.001 F229.1825 
X1.4509 C-28.874 F214.8495 
X1.5004 C-32.134 F200.713 
X1.5544 C-35.178 F187.3359 
X1.5805 C-36.695 F185.613 
X1.6022 C-38.279 F193.7671 
X1.6193 C-39.915 F200.109 
X1.6315 C-41.59 F204.7619 
X1.639 C-43.289 F207.8149 
X1.6414 C-45. F209.3271 
X1.639 C-46.711 
X1.6315 C-48.41 F207.8149 
X1.6193 C-50.085 F204.7619 
X1.6022 C-51.721 F200.109 
X1.5805 C-53.305 F193.7672 
X1.5544 C-54.822 F185.6131 
X1.4919 C-58.385 F188.4147 
X1.4367 C-62.167 F203.8597 
X1.389 C-66.159 F218.9762 
X1.3491 C-70.344 F233.213 
X1.3172 C-74.7 F245.9516 
X1.2934 C-79.194 F256.5552 
X1.278 C-83.788 F264.4336 
X1.271 C-88.438 F269.1147 
X1.2724 C-93.097 F270.3099 
X1.2821 C-97.718 F267.9557 
X1.3001 C-102.256 F262.2217 
X1.3262 C-106.67 F253.4836 
X1.3602 C-110.927 F242.2677 
X1.4019 C-115.001 F229.1825 
X1.4509 C-118.874 F214.8495 
X1.5004 C-122.134 F200.713 
X1.5544 C-125.178 F187.3359 
X1.5805 C-126.695 F185.613 
X1.6022 C-128.279 F193.7671 
X1.6193 C-129.915 F200.109 
X1.6315 C-131.59 F204.7619 
X1.639 C-133.289 F207.8149 
X1.6414 C-135. F209.3271 
X1.639 C-136.711 
X1.6315 C-138.41 F207.8149 
X1.6193 C-140.085 F204.7619 
X1.6022 C-141.721 F200.109 
X1.5805 C-143.305 F193.7672 
X1.5544 C-144.822 F185.6131 
X1.4919 C-148.385 F188.4147 
X1.4367 C-152.167 F203.8597 
X1.389 C-156.159 F218.9762 
X1.3491 C-160.344 F233.213 
X1.3172 C-164.7 F245.9516 
X1.2934 C-169.194 F256.5552 
X1.278 C-173.788 F264.4336 
X1.271 C-178.438 F269.1147 
X1.2724 C-183.097 F270.3099 
X1.2821 C-187.718 F267.9557 
X1.3001 C-192.256 F262.2217 
X1.3262 C-196.67 F253.4836 
X1.3602 C-200.927 F242.2677 
X1.4019 C-205.001 F229.1825 
X1.4509 C-208.874 F214.8495 
X1.5004 C-212.134 F200.713 
X1.5544 C-215.178 F187.3359 
X1.5805 C-216.695 F185.613 
X1.6022 C-218.279 F193.7671 
X1.6193 C-219.915 F200.109 
X1.6315 C-221.59 F204.7619 
X1.639 C-223.289 F207.8149 
X1.6414 C-225. F209.3271 
X1.639 C-226.711 
X1.6315 C-228.41 F207.8149 
X1.6193 C-230.085 F204.7619 
X1.6022 C-231.721 F200.109 
X1.5805 C-233.305 F193.7672 
X1.5544 C-234.822 F185.6131 
X1.4919 C-238.385 F188.4147 
X1.4367 C-242.167 F203.8597 
X1.389 C-246.159 F218.9762 
X1.3491 C-250.344 F233.213 
X1.3172 C-254.7 F245.9516 
X1.2934 C-259.194 F256.5552 
X1.278 C-263.788 F264.4336 
X1.271 C-268.438 F269.1147 
X1.2724 C-273.097 F270.3099 
X1.2821 C-277.718 F267.9557 
X1.3001 C-282.256 F262.2217 
X1.3262 C-286.67 F253.4836 
X1.3602 C-290.927 F242.2677 
X1.4019 C-295.001 F229.1825 
X1.4509 C-298.874 F214.8495 
X1.5004 C-302.134 F200.713 
X1.5544 C-305.178 F187.3359 
X1.5805 C-306.695 F185.613 
X1.6022 C-308.279 F193.7671 
X1.6193 C-309.915 F200.109 
X1.6315 C-311.59 F204.7619 
X1.639 C-313.289 F207.8149 
X1.6414 C-315. F209.3271 
X1.639 C-316.711 
X1.6315 C-318.41 F207.8149 
X1.6193 C-320.085 F204.7619 
X1.6022 C-321.721 F200.109 
X1.5805 C-323.305 F193.7672 
X1.5544 C-324.822 F185.6131 
X1.4919 C-328.385 F188.4147 
X1.4367 C-332.167 F203.8597 
X1.389 C-336.159 F218.9762 
X1.3491 C-340.344 F233.213 
X1.3172 C-344.7 F245.9516 
X1.2934 C-349.194 F256.5552 
X1.278 C-353.788 F264.4336 
X1.271 C-358.438 F269.1147 
X1.2724 C-363.097 F270.3099 
X1.2821 C-367.718 F267.9557 
X1.3001 C-372.256 F262.2217 
X1.3262 C-376.67 F253.4836 
X1.3602 C-380.927 F242.2677 
X1.4019 C-385.001 F229.1825 
X1.4509 C-388.874 F214.8495 
X1.5004 C-392.134 F200.713 
X1.5544 C-395.178 F187.3359 
X1.5805 C-396.695 F185.613 
X1.6022 C-398.279 F193.7671 
X1.6193 C-399.915 F200.109 
X1.6315 C-401.59 F204.7619 
X1.639 C-403.289 F207.8149 
X1.6414 C-405. F209.3271 
X1.639 C-406.711 
X1.6315 C-408.41 F207.8149 
X1.6193 C-410.085 F204.7619 
X1.6022 C-411.721 F200.109 
X1.5805 C-413.305 F193.7672 
X1.5544 C-414.822 F185.6131 
X1.4919 C-418.385 F188.4147 
X1.4367 C-422.167 F203.8597 
X1.389 C-426.159 F218.9762 
X1.3491 C-430.344 F233.213 
X1.3172 C-434.7 F245.9516 
X1.2934 C-439.194 F256.5552 
X1.278 C-443.788 F264.4336 
X1.271 C-448.438 F269.1147 
X1.2724 C-453.097 F270.3099 
X1.2821 C-457.718 F267.9557 
X1.3001 C-462.256 F262.2217 
X1.3262 C-466.67 F253.4836 
X1.3602 C-470.927 F242.2677 
X1.4019 C-475.001 F229.1825 
X1.4509 C-478.874 F214.8495 
X1.5004 C-482.134 F200.713 
X1.5544 C-485.178 F187.3359 
X1.5805 C-486.695 F185.613 
X1.6022 C-488.279 F193.7671 
X1.6193 C-489.915 F200.109 
X1.6315 C-491.59 F204.7619 
X1.639 C-493.289 F207.8149 
X1.6414 C-495. F209.3271 
X1.639 C-496.711 
X1.6315 C-498.41 F207.8149 
X1.6193 C-500.085 F204.7619 
X1.6022 C-501.721 F200.109 
X1.5805 C-503.305 F193.7672 
X1.5544 C-504.822 F185.6131 
X1.4919 C-508.385 F188.4147 
X1.4367 C-512.167 F203.8597 
X1.389 C-516.159 F218.9762 
X1.3491 C-520.344 F233.213 
X1.3172 C-524.7 F245.9516 
X1.2934 C-529.194 F256.5552 
X1.278 C-533.788 F264.4336 
X1.271 C-538.438 F269.1147 
X1.2724 C-543.097 F270.3099 
X1.2821 C-547.718 F267.9557 
X1.3001 C-552.256 F262.2217 
X1.3262 C-556.67 F253.4836 
X1.3602 C-560.927 F242.2677 
X1.4019 C-565.001 F229.1825 
X1.4509 C-568.874 F214.8495 
X1.5004 C-572.134 F200.713 
X1.5544 C-575.178 F187.3359 
X1.5805 C-576.695 F185.613 
X1.6022 C-578.279 F193.7671 
X1.6193 C-579.915 F200.109 
X1.6315 C-581.59 F204.7619 
X1.639 C-583.289 F207.8149 
X1.6414 C-585. F209.3271 
X1.639 C-586.711 
X1.6315 C-588.41 F207.8149 
X1.6193 C-590.085 F204.7619 
X1.6022 C-591.721 F200.109 
X1.5805 C-593.305 F193.7672 
X1.5544 C-594.822 F185.6131 
X1.4919 C-598.385 F188.4147 
X1.4367 C-602.167 F203.8597 
X1.389 C-606.159 F218.9762 
X1.3491 C-610.344 F233.213 
X1.3172 C-614.7 F245.9516 
X1.2934 C-619.194 F256.5552 
X1.278 C-623.788 F264.4336 
X1.271 C-628.438 F269.1147 
X1.2724 C-633.097 F270.3099 
X1.2821 C-637.718 F267.9557 
X1.3001 C-642.256 F262.2217 
X1.3262 C-646.67 F253.4836 
X1.3602 C-650.927 F242.2677 
X1.4019 C-655.001 F229.1825 
X1.4509 C-658.874 F214.8495 
X1.5004 C-662.134 F200.713 
X1.5544 C-665.178 F187.3359 
X1.5805 C-666.695 F185.613 
X1.6022 C-668.279 F193.7671 
X1.6193 C-669.915 F200.109 
X1.6315 C-671.59 F204.7619 
X1.639 C-673.289 F207.8149 
X1.6414 C-675. F209.3271 
X1.639 C-676.711 
X1.6315 C-678.41 F207.8149 
X1.6193 C-680.085 F204.7619 
X1.6022 C-681.721 F200.109 
X1.5805 C-683.305 F193.7672 
X1.5544 C-684.822 F185.6131 
X1.4919 C-688.385 F188.4147 
X1.4367 C-692.167 F203.8597 
X1.389 C-696.159 F218.9762 
X1.3491 C-700.344 F233.213 
X1.3172 C-704.7 F245.9516 
X1.2934 C-709.194 F256.5552 
X1.278 C-713.788 F264.4336 
X1.271 C-718.438 F269.1147 
X1.2724 C-723.097 F270.3099 
X1.2821 C-727.718 F267.9557 
X1.3001 C-732.256 F262.2217 
X1.3262 C-736.67 F253.4836 
X1.3602 C-740.927 F242.2677 
X1.4019 C-745.001 F229.1825 
X1.4509 C-748.874 F214.8495 
X1.5004 C-752.134 F200.713 
X1.5544 C-755.178 F187.3359 
X1.5805 C-756.695 F185.613 
X1.6022 C-758.279 F193.7671 
X1.6193 C-759.915 F200.109 
X1.6315 C-761.59 F204.7619 
X1.639 C-763.289 F207.8149 
X1.6414 C-765. F209.3271 
X1.639 C-766.711 
X1.6315 C-768.41 F207.8149 
X1.6193 C-770.085 F204.7619 
X1.6022 C-771.721 F200.109 
X1.5805 C-773.305 F193.7672 
X1.5544 C-774.822 F185.6131 
X1.4919 C-778.385 F188.4147 
X1.4367 C-782.167 F203.8597 
X1.389 C-786.159 F218.9762 
X1.3491 C-790.344 F233.213 
X1.3172 C-794.7 F245.9516 
X1.2934 C-799.194 F256.5552 
X1.278 C-803.788 F264.4336 
X1.271 C-808.438 F269.1147 
X1.2724 C-813.097 F270.3099 
X1.2821 C-817.718 F267.9557 
X1.3001 C-822.256 F262.2217 
X1.3262 C-826.67 F253.4836 
X1.3602 C-830.927 F242.2677 
X1.4019 C-835.001 F229.1825 
X1.4509 C-838.874 F214.8495 
X1.5004 C-842.134 F200.713 
X1.5544 C-845.178 F187.3359 
X1.5805 C-846.695 F185.613 
X1.6022 C-848.279 F193.7671 
X1.6193 C-849.915 F200.109 
X1.6315 C-851.59 F204.7619 
X1.639 C-853.289 F207.8149 
X1.6414 C-855. F209.3271 
X1.639 C-856.711 
X1.6315 C-858.41 F207.8149 
X1.6193 C-860.085 F204.7619 
X1.6022 C-861.721 F200.109 
X1.5805 C-863.305 F193.7672 
X1.5544 C-864.822 F185.6131 
X1.4919 C-868.385 F188.4147 
X1.4367 C-872.167 F203.8597 
X1.389 C-876.159 F218.9762 
X1.3491 C-880.344 F233.213 
X1.3172 C-884.7 F245.9516 
X1.2934 C-889.194 F256.5552 
X1.278 C-893.788 F264.4336 
X1.271 C-898.438 F269.1147 
X1.2724 C-903.097 F270.3099 
X1.2821 C-907.718 F267.9557 
X1.3001 C-912.256 F262.2217 
X1.3262 C-916.67 F253.4836 
X1.3602 C-920.927 F242.2677 
X1.4019 C-925.001 F229.1825 
X1.4509 C-928.874 F214.8495 
X1.5004 C-932.134 F200.713 
X1.5544 C-935.178 F187.3359 
X1.5805 C-936.695 F185.613 
X1.6022 C-938.279 F193.7671 
X1.6193 C-939.915 F200.109 
X1.6315 C-941.59 F204.7619 
X1.639 C-943.289 F207.8149 
X1.6414 C-945. F209.3271 
X1.639 C-946.711 
X1.6315 C-948.41 F207.8149 
X1.6193 C-950.085 F204.7619 
X1.6022 C-951.721 F200.109 
X1.5805 C-953.305 F193.7672 
X1.5544 C-954.822 F185.6131 
X1.4919 C-958.385 F188.4147 
X1.4367 C-962.167 F203.8597 
X1.389 C-966.159 F218.9762 
X1.3491 C-970.344 F233.213 
X1.3172 C-974.7 F245.9516 
X1.2934 C-979.194 F256.5552 
X1.278 C-983.788 F264.4336 
X1.271 C-988.438 F269.1147 
X1.2724 C-993.097 F270.3099 
X1.2821 C-997.718 F267.9557 
X1.3001 C-1002.256 F262.2217 
X1.3262 C-1006.67 F253.4836 
X1.3602 C-1010.927 F242.2677 
X1.4019 C-1015.001 F229.1825 
X1.4509 C-1018.874 F214.8495 
X1.5004 C-1022.134 F200.713 
X1.5544 C-1025.178 F187.3359 
X1.5805 C-1026.695 F185.613 
X1.6022 C-1028.279 F193.7671 
X1.6193 C-1029.915 F200.109 
X1.6315 C-1031.59 F204.7619 
X1.639 C-1033.289 F207.8149 
X1.6414 C-1035. F209.3271 
X1.639 C-1036.711 
X1.6315 C-1038.41 F207.8149 
X1.6193 C-1040.085 F204.7619 
X1.6022 C-1041.721 F200.109 
X1.5805 C-1043.305 F193.7672 
X1.5544 C-1044.822 F185.6131 
G0 Z.044 
M47 
G97 T1100 
G0 G59 X0 Z0 T0 
M05 
M01 
 

I can also upload the mastercam file if that would help.  Just cant figure this out for the life of me.  

[#Rekd™]

I am guessing it might be the feed rate.

[crazy^millman]

I would not reduce the size of the endmill I would increase the size of the endmill. The smaller the endmill the worse I would expect to see the issue. When is the last time the machine was tuned on the C Axis? What is the runout of the endmill? I assume your using a ER collet system. Have you looked at the Shrink to ER systems? Yes they stick the tool further away from the Live Tool, but hold the whole Shrink in an ER which make it more stable. What is the filter tolerance on the C Axis toolpath? I see a lot of code for cutting a square shape what happens when you try to reduce the amount of code? Better or worse? 

To add a Mastercam file don't use the quick response use the expanded response. 

[cncappsjames]

There's always a little play/backlash in the 90Deg. milling tool holders. Perhaps try conventional cutting?  

[civiceg]

Does your machine support G112/G12.1 for polar coordinate interpolation?

[JoshC]

12 minutes ago, civiceg said:

Does your machine support G112/G12.1 for polar coordinate interpolation?

that is the fix for his problem, you need to use G107 or G112 or G12.1 or whatever Face milling cycle codes the machine supports. If you are using a custom post it should be found in misc values, set the FACE milling cycle to On by setting the specific misc value to 1 (see image below)

[crazy^millman]

1 hour ago, civiceg said:

Does your machine support G112/G12.1 for polar coordinate interpolation?

That was going to be my next question. Good call!!

[Joe777]

Just curious: what equipment are you using? Rectangular part, x and c axis in g-code.  Well: make sure that the geometry you are cutting are lines and not splines. G code seems to be consistent with the finishing results that you are seeing. As others have mentioned: your feed is too high, how is the feed calculated for rotary axis?