4th axis formula

[BOATDUDEGUY]

Okay lets forget the small part

The detail on the end of the long one is my question

I had run something similar to this on a 4th axis and programming it was another story

I saw how it was layed out in 2d along y in the software

What I would like to know is the formula for calculating it

[EX-wccprogrammer]

Good luck getting your head wrapped around this... It is way easier to let the CAD do it.

 

But, if you insist.... Here are some spline formulas:

 

http://www.brnt.eu/phd/node11.html

[BOATDUDEGUY]

wow ya theres no way im getting any of that without a teacher

but it didnt seem that complicated when the programmer explained it

the way i tried was drawing the detail as show on print then wrapping it to the dia but it never worked out

and the formula wasnt all that crazy like those, or mayb its in there i wouldnt know if it was though

[Colin Gilchrist]

Instead of trying to figure it out, just orient the part as it sits on your rotary (about X?). Then use the contour Toolpath, and in the rotary options, use "unroll". This tells Mastercam to use the already "wrapped" geometry, and unrolls it behind the scenes for you. Much easier to do it this way...

[EX-wccprogrammer]

I can do it graphically, but don't know how to do it with a formula.

[Colin Gilchrist]

You can also use Xform > Roll to 'unroll' the geometry and create the flat contour from the wrapped geometry...

[djstedman]

Its important to note with this type of form, if your cutting it on a rotary that you can only get the 'correct' form at a defined diameter unless your tool has a diameter of zero.

 

Since the tangency point of your tool will change dependent on the lead angle you are cutting as a function of the diameter of the tool and the diameter where the tool is contacting the work.

 

If your using a 1 inch tool cutting the end of a flat cylinder then the point of contact on the tool will always be on c/l of rotary in Y regardless the diameter of the cylinder your cutting, however if you are cutting a 45 degree angle on the end of a cylinder and keeping your cutter on c/l of the cylinder your point of contact on the cutter will be at c/l in Y at c/l of rotary in Z but will move progressively off of c/l as the diameter increases given the tangency point of the cylinder to a diameter and the fact your cutting an angle..

 

Im sure I have butchered trying to explain this, but depending on how accurate the form you are trying to cut we have sometimes had to profile parts like this rather than finishing on the rotary in order to obtain the correct result..

 

What im trying to explain above is why in the past when people made barrel cams that needed slots for a cam follower they would always define the diameter of the cam follower on the print so the part could be cut using a cutter of the same diameter so tangency points would be maintained..

 

Anyhow .. just figured I would mention this since if you havent done many of these forms its easy to think its a simple unroll and cut.. but it depends a lot on diameter of the cutter and diameter of the part and how the print defines the form..

 

lol now I feel like I rambled enough .. not sure if this will actually help anyone though..

[BOATDUDEGUY]

Instead of trying to figure it out, just orient the part as it sits on your rotary (about X?). Then use the contour Toolpath, and in the rotary options, use "unroll". This tells Mastercam to use the already "wrapped" geometry, and unrolls it behind the scenes for you. Much easier to do it this way...

 

 

Well this is for the sake of say not having a model

So we had to draw it ourselves and we did not understand it would not work out

We finally ended up sending it to the reseller and they did it

 

So thats basically what this thread was for to be able to draw something like this when not supplied with a model from the customer

[djstedman]

If as it sounds it was defined given as a contour in a 2D developed view at a set diameter.

 

If thats the case then the form is radial, meaning that at any height along the contour a line projected out from c/l will be perpendicular to the axis of the part and will match the face of the part.

 

I am going from memory here but I am pretty sure the form can be created doing something like this..

 

The first step to drawing this is to draw the form as shown in the 2D developed view and then use XForm -> Roll to wrap it on a diameter the size indicated on the print.

 

Once thats done you can create points at the inside diameter of the form by creating lines that extend out from centerline and intersect the spline created using xfrom roll.

 

Now create a diameter the size of the ID from the end view of the part and intersect all those lines with it.

 

Using those points you can create a spline that is the corresponding inside rail of the form.

 

Once you have the inside and outside rail you should be able to create a swept sutrface out of it.

 

Im not entirely sure thats how I did it exactly cause its been awhile, but thats basically how I did it.. there may be easier ways though.. not sure since once I found something that worked I didnt mess with it much more..

[KMartin]

Hi everyone - I need some help with this part that has a slot

in it . I need to know if I have drawn this properly .I draw the

lines from the print then projected them to the surface .

The only problem I see is the rad from the cutter on the

inside slot .Thanks for any help .

JIM.MCX-6

[RayD]

Hi everyone - I need some help with this part that has a slot

in it . I need to know if I have drawn this properly .I draw the

lines from the print then projected them to the surface .

The only problem I see is the rad from the cutter on the

inside slot .Thanks for any help .

 

If that's the shape your supposed to have it looks fine, if the 2d Geometry is unrolled on your drawing the toolpath is wrong. you need to doublecheck your print if the dimensions are "topview" or Unrolled.

 

There is a big difference in rolling/unrolling Geometry and Projecting onto surface.

 

Using Rolldie will give you walls that point to center of rotation, using axis sub on a toolpath will give you straight walls. Use the appropriate function to achieve the result you are after.

[djstedman]

I agree, in order to answer your question correctly I would need to see how the shape was defined on the print..

[KMartin]

I have the line layout on level 10 . Drawn

as per print .The description says

Layout - Cam Path Development .

One end says Eject cycle

other end says load cycle .

[djstedman]

Based on the description cam path development, and the notation in degrees I would say this cannot be projected and must instead be rolled around the correct diameter.

 

I used the formula Pi * D = Circumfrence to get 9.032 / PI = 2.8749748920119973453291163015611

 

This works since the developed view is 360 degrees total and therefore its length must equal the circumfrence of the part.

 

Given that we can figure out our diameter to roll the part on which is 2.874974

 

Anyhow.. using xform roll you can then roll the lines onto that diameter and you will see the form is very different than the one you have gotten with projecting the lines.

 

As for how to cut it, that depends on the machine.. but it appears trying to do it on a 4 axis would result in undercuts.. only have had limited time to play with it so im not sure really without looking into it more.

[John Summers]

ROLLDIE c-hook offsets each way from the slot centerline when you use the SLOT option. There is no 'formula' for this--it takes an entire algorithm, which is a series of formulas. If you want a formula, you should look for the formula that creates the slot centerline if it is a cam. Wait... that's an even more complicated algorithm.

In these kinds of parts, if you model the walls, opposite sides of the slot are not parallel as seen by the pin. That's why ROLLDIE was invented. If you have problems creating a cam profile, I can help you with that.

[Jayson Kramer]

John, I have to say Hi how long has it been sense you have chimed in. glad to see you here . hope you are doing well sir.

[John Summers]

Hi Jay! I still work on the odd program once in a while.

BOATDUDE -- It was not clear which thing you wanted a formula for, the cam profile or rolling up (or unrolling) the contour.

[BOATDUDEGUY]

Hi Jay! I still work on the odd program once in a while.

BOATDUDE -- It was not clear which thing you wanted a formula for, the cam profile or rolling up (or unrolling) the contour.

 

Tell you the truth I dont even know which is needed for what im trying to learn

Wish I had a print to upload and show

[BOATDUDEGUY]

this is more helpful to show what i want to model

[BOATDUDEGUY]

Hi Jay! I still work on the odd program once in a while.

BOATDUDE -- It was not clear which thing you wanted a formula for, the cam profile or rolling up (or unrolling) the contour.

 

John thanks again for helping me understand this

It was indeed the rolldie

[KMartin]

Hi everyone - can I get some help on how to use xform roll .

I need to wrap the red lines around the red circle .Thanks

for the help . I hope that I'm not taking over this thread .

p.s. projecting the lines will not work .

JIM.MCX-6

[RayD]

Roll = Dim you want to roll around, CW or CCW is the direction it wraps around the part.

ROLL.MCX-6

[John Summers]

ROLL will wrap these lines on a cylinder, but if you want to machine a groove, you can do it right from the flat with ROLLDIE. However, if you want to machine a slot with ROLLDIE, you should drive the centerline geometry. It also looks like the slot, as designed, will be narrower in the angled portions. That will fix itself if you machine from the centerline. If there's a pin or follower riding in the slot, you might need a radius in the sharp corners.

[Jayson Kramer]

John can you do a sample on his file and share it here?