We have been successful with the front side operations on building blocks parts 1-10 and even on the backside operations, HOWEVER when trying to chamfer the backside of the building block parts we run into a bunch of problems.
For example on the 3m 2nd op, we contour around leaving .030, then face to correct thickness, then chamfer the circular edge at .010 to match the top. The problem is the chamfer on the bottom of the part usually looks significantly different than the .010 on the top of the part. Many times the bottom side chamfer will also be heavier in the front than the back. We have had the same issue with the 4m where the chamfer was heavier on the left side of the triangle than on the right. If someone could help with specific instructions on how you would go about doing this my students and I sure would appreciate it. Chamfers in general have been a real struggle for us although we’ve come a long way on our op 1 chamfers.
I’m guessing being off even the slightest amount would create these issues since the chamfer is only .010 so I need techniques on proper setup, CAM, etc. We use a Haimer 3d sensor for all setups (we do NOT have a probe). Thanks in advance.
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@KevinBradley I have to assumptions or possible candidates for the error. My first thought is that the machine may have some slack in the screws. Like you said if it was off .002 that would make one side .012 in the other side .008. That could account for your left side right side error. The other front to back issue could be varying torque pressure on your Vice if you tighten the vice handle more it will reposition the part. This might be inopportune time for a Learning lesson. Put yourself and indicator on the solid jaw of your Vice. Tighten the Vice by hand with varying pressures. The indicator will show a change in location with the varying tightening pressure. A way to get Beyond this would be to use a torque wrench and it must be used properly. Put your part in device and running and indicator over the top of the park to see if it has tipped front to back or left to right.
I hope this is some valuable information for you.
Regards,
Travis Sherwood
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The way to determine if their slack in your machine screws would be on your own part indicated in always moving in the x+ y+ direction. Then raise the Z up jog in the opposite direction MDI back to x 0 y 0 and check your reading. Whenever I work in the mold shop we always picked up our zero pinhole going in a positive direction with the axis travel. Even if it was a brand new machine.
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Thank you very much Travis. This is certainly helpful. We will try this out. I’m always chalking our issues up to user error since we are new but will certainly follow the procedures you lay out above and check it. We are using a torque wrench set to 35 ft/lbs for both our first and second operation vises so I know that is at least consistent. However I do realize it could still be lifting ever so slightly. Thanks again!
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Thank you Rumpelstiltskin! We will try this as well.
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Questions? When clamping the 2nd op of all the parts that have a 1.950 diameter, are you using soft jaws having the 1.950 diameter machined into the jaws? If so you may want to verify if your G54 zero position is off. Indicate the diameter of the part after moving to G54 G00 X0 Y0. If the indicator is zeroed out, then you may have some mechanical issues with your lead screws. Check out the topic 2nd Op Techniques for Mill Building Blocks
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You might want to make a master that you can use to check work position. Make the triangular shape with a 1/2 bore in true center of triangle. then clamp master in jaws and verify G54 X0 Y0
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