Good evening all,
The problem is simply a circular runout (not total indicated) issue. I skimmed new pie jaws because my first set of pie jaws didn't have quite enough meat left on them. Circular runout was heading toward the top of my runout tolerance, which is 0.002 on all OD surfaces with the exception of the grooves.
I bored the new set of aluminum pie jaws out by preloading them with a small steel rod with a known diameter. The rod was held by the full length of the jaws. I did not drill to make a hole for a plug. 4 parts ran and indicated 0.002 to 0.003 circular runout.
MATL: 5.75 x 0.75 wall. 4140 Steel Q&T / 295 BHN
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First turning operation:
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Prerough the blank's OD and ID on an Okuma LB15 held with OD hard jaws.
Face & OD roughed with WNMG 432 carbide, G97: S400 F0.010, 0.03 depth of cut. Finished with WNMG 432 carbide, 0.01 depth of cut, G96: S350 F0.008.
The blank is roughed and finished on the OD, flipped, roughed and finished on the OD and ID.
ID roughed with a 1" boring bar WNMG 432 carbide, G97: S500 F0.012, 0.06 doc per pass. 0.01 left for finish pass.
Finished with a 1" boring bar WNMG 431 carbide, G97: S450 F0.008, 0.015 depth of cut. ID turned to 4.63 +-0.001.
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Final operation details:
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Machine: Haas SL-20 in good working order.
Workholding: fairly new 8" kitagawa 3 jaw chuck / aluminum ID pie jaws / bored .0024 over / bored over mid stroke. Part held at 100 PSI chuck pressure. Chuck is greased every 4 to 8 hours with either marine grease or white lithium grease. Counterbore sits nearest spindle.
Program structure:
1. Roughed with CCMT3252 KCP25 POS carbide.
Faced 0.025 DOC, G96 S350 F0.012.
Rough OD 0.020 DOC, G96 S325 F0.018, canned.
Left 0.015 on OD and 0.01 on face for finish pass.
2. Rough grooves.
3. Finished with VNMG 431
Finish face and OD. G00 to clearance distance.
Finish face going downward. G96 S750 F0.008.
Finish OD from the front to the back. G96 S750 F0.008.
4. Finish grooves.
5. Chamfer front of ID with 1" boring bar CNMG 432
The ring is not spinning during operation.
Circular runout on the OD is checked on a 90 degree v-block with 0.001 and 0.0005 graduation indicator. I have researched that there is a certain amount of error when using a v-block with a given angle when measuring a 3-lobed part. Any input on this as well?
The problem is simply a circular runout (not total indicated) issue. I skimmed new pie jaws because my first set of pie jaws didn't have quite enough meat left on them. Circular runout was heading toward the top of my runout tolerance, which is 0.002 on all OD surfaces with the exception of the grooves.
I bored the new set of aluminum pie jaws out by preloading them with a small steel rod with a known diameter. The rod was held by the full length of the jaws. I did not drill to make a hole for a plug. 4 parts ran and indicated 0.002 to 0.003 circular runout.
MATL: 5.75 x 0.75 wall. 4140 Steel Q&T / 295 BHN
///////////////////////////
First turning operation:
Prerough the blank's OD and ID on an Okuma LB15 held with OD hard jaws.
Face & OD roughed with WNMG 432 carbide, G97: S400 F0.010, 0.03 depth of cut. Finished with WNMG 432 carbide, 0.01 depth of cut, G96: S350 F0.008.
The blank is roughed and finished on the OD, flipped, roughed and finished on the OD and ID.
ID roughed with a 1" boring bar WNMG 432 carbide, G97: S500 F0.012, 0.06 doc per pass. 0.01 left for finish pass.
Finished with a 1" boring bar WNMG 431 carbide, G97: S450 F0.008, 0.015 depth of cut. ID turned to 4.63 +-0.001.
///////////////////////////////
Final operation details:
Machine: Haas SL-20 in good working order.
Workholding: fairly new 8" kitagawa 3 jaw chuck / aluminum ID pie jaws / bored .0024 over / bored over mid stroke. Part held at 100 PSI chuck pressure. Chuck is greased every 4 to 8 hours with either marine grease or white lithium grease. Counterbore sits nearest spindle.
Program structure:
1. Roughed with CCMT3252 KCP25 POS carbide.
Faced 0.025 DOC, G96 S350 F0.012.
Rough OD 0.020 DOC, G96 S325 F0.018, canned.
Left 0.015 on OD and 0.01 on face for finish pass.
2. Rough grooves.
3. Finished with VNMG 431
Finish face and OD. G00 to clearance distance.
Finish face going downward. G96 S750 F0.008.
Finish OD from the front to the back. G96 S750 F0.008.
4. Finish grooves.
5. Chamfer front of ID with 1" boring bar CNMG 432
The ring is not spinning during operation.
Circular runout on the OD is checked on a 90 degree v-block with 0.001 and 0.0005 graduation indicator. I have researched that there is a certain amount of error when using a v-block with a given angle when measuring a 3-lobed part. Any input on this as well?