4th axis helix

[rgollar]

I hope I can explain this clear enough, so hear I go. I am machining a slot in round stock using the forth axis. The slot is .790 long and the forth axis needs to turn so it is 30 degrees. I found if I do a X.79A95.0 it does it to 30 degrees. I did this by trial and error, what im wondering is there a math formula that tells me how much I need to turn the 4th axis to get the 30 degree angle at a given X distence. I hope I explained this good enough. Thanks in advance for the help.

[crazy^millman]

30/360 will give you the amount of rotation you need if using the helix in Mastercam and want to use that as a chain. Which is .08333 and if you gve the radius and are in right view when you use the helix funstion it should be preet close to what you need. Another way to do this is to make a line that repsents the X travel and A travel as a Y move and then do a axis sub and that should give you some very clean code.

 

 

HTH

[John Summers]

Rgollar, your description is confusing. Is the slot on a 30 degree helix, or do you want to rotate 30 degrees? Also, is the slot length .790, or is the slot .790 in X?

If the slot length on the diagonal is .790, then the Y value in the flat (or unrolled) is .395.

Y = sin(30)*.790 = .395

When you use axis substitution, you have to declare a diameter in the ROTARY AXIS box. If you declare the diameter correctly, you don't need to know the angle, but here's how you can figure out what it should be:

Let CC = circumference = pi*diameter

A/360 = Y/CC This is the proportion formula you need to find the relationship between the rotary angle A and the flat layout Y.

Then A = 360*Y/CC and Y = A*CC/360

A will change depending on the diameter.

[crazy^millman]

John one thing about the Helix is the rotation not being exact to the angle needed to make it work on the parts I have seen. Read the thread where I made a solid part for someone and it was not exact. It is close but off and I would not really recommend someone really use it for parts just for visual is tight tolerance is required. What are your thoughts on using it and it's accuracy?

[John Summers]

Crazy,

I couldn't find your thread about a helix not being exact. If you send me the part, if you still have it, I could sort it out. The problem with helixes is that the helix angle is only valid at a particular diameter, which can make it hard to measure or evaluate. I would like to see the part.

RGOLLAR: When you mill a helical slot, you get a much cleaner slot if you use the slot centerline for geometry, and cut the slot with ROLLDIE.DLL.

[rgollar]

The slot is .790 long in the X direction. Im starting at X0.0 A0 and moving to X.79 A95.0, which seems to give me the 30 degrees angle when I lay it in a vblock and check it in the shadow graph. The customer wont let us show the part print to any one other wise I would make this alot clearer and post it. The dia. of the part is .551 with the slot being .06 dp. and .06 wide. The shaft has 11 slot around the dia. which comes out to about 32.7272 degree turn in the a axis for each slot to start. So what im doing is a helix slot the is at a 30 degree angle from the center line but the helix angle is about 95 degree worth of turn in the a axis. Im sorry is was gone for a few days but I really aprreciate you guys help.

[John Summers]

CC = PI * .551 = 1.731 circumference

A = 360 * .577/1.731 = 120 degrees

I'll send you a picture of the slot CENTERLINES, both in the flat and rolled up. The best approach is to machine the centerlines using ROLLDIE and the SLOT option. You can use a cutter smaller than .06 to rough down the middle, then finish with the slot option.

[rgollar]

Thanks alot John your help is much apreciated as everyone else is.