Preparing a Model for Rotary Machining

[jim_vv]

Greetings,

I have had a few projects come in that I would have liked to machine rotary on my indexer parallel to the Y axis on my machine. I have not had any success in getting the models to machine properly so I have resorted to multi sided machining strategies instead. I am currently using ArtCAM Pro 2008.

Currently, I have a 3D model that I would like to machine with a rotary strategy I have not had any success when I follow all of the Rotary machining documentation and posts that I can find and have tried everything that I can come up with. I have attached a text document of a very helpful post that I found on this forum which I followed. I would appreciate any help that anyone may offer.

I have a few observations/questions regarding setting the project up.

This particular model requires that it be unwrapped onto a small cylinder because it is very small at the top. After unwrapping and then wrapping, the model looks great, but the machine relief toolpaths do not follow the relief. Unwrapping onto a larger cylinder helps, but the toolpath is still not following the part correctly and obviously ruins the part. I have attached screen shots of the model and different views of unwrapping onto a cylinder, creating rotary relief as well as toolpath simulations.

I have been told that the bulbous contours in the toolpath simulation are an optical illusion. It is not, I have attached an image of the actual part which looks just as the simulation.

It appears that the toolpath stepover is calculated at the cylinder dimension, so the stepover is far too great at the larger diameters of the part. To get by this, I have created four limiting vectors and machined the part in four sections with all different stepover values to get an acceptable finish and machine time.

On this model, I will have to resort to a four sided strategy, but I sure would like to know if I am doing something wrong, if some parts just cannot be machined rotary, or if it is just a limitation in the software.

How does an ArtCAM user decide whether a part should be machined rotary or multi-sided? What criteria should I consider?

I will attach more images in subsequent posts

Kind regards,
Jim van Vegten

[jim_vv]

More images

[jim_vv]

The bulbous finished part on a .375" cylinder

[myxpykalix]

Jim
I'm going to make a couple guesses based on the pictures and I could be totally wrong. But in the two posts the 2nd picture in post 1 and 2, you see something going down below your material surface? That may have a bearing on the height of your protrusions. I don't know how to tell you to eliminate that based on those pictures. Maybe take a few more screenshots of different angles?
Possibly you are getting that error in the pic because your model doesn't go entirely 360 degrees around the model? Maybe increase the model size a degree or two?
Maybe one of the experts will know.:confused:
btw...what the heck is it?

[bob_dodd]

Jim, in the first post , first picture , looking at the gnomen the model needs to be rotated 90 deg to lay in the Y axis , it looks like you did this in the second picture, You also need to center the model , your z dia. is 8.8965 , in the fill in box for the Z -4.34325 this will center it in the z then try unwrapping . Hope this helps

[jim_vv]

Greetings, Bob

Thank you for your help. The fist image was just to show what the model is supposed to look like. I rotated the model 90 degrees in X and then lowered it into the material 1/2 the Z height in the Paste 3D Model window before unwrapping it. I have attached a screen shot.

Kind regards,

JIM

[jim_vv]

Greetings, Jack

The part is a Gothic Spire. There are supposed to twelve of these going on top of an antique cabinet.

Kind regards,

JIM

[Brady Watson]

How does an ArtCAM user decide whether a part should be machined rotary or multi-sided? What criteria should I consider?


Some models are just not conducive to continuous rotary machining for various reasons. My general rule is if the model has anything other than stub length 'appendages', then it should be broken apart in pieces prior to preparing the main body for machining. Your model looked like it machined OK towards the tip, but you have to contend with that pesky 'tube' that runs down the center of the model when unwrapping. There is no tried & true 100% rule to what can and can't be rotary machined - since every model is different. Features on the surface of the main body should not protrude very far - Statue of Liberty arm & torch being a good example of a model that needs to be broken up before machining in multiple parts.

I know you are invested in AC, but Aspire does an amazing job with rotary models, both unwrapping as well as efficiently machining them. There is no 'tube' to fool with or confusion with what way the model needs to be oriented. You setup a Rotary Project, fill in what size you want it to be & then import your 3D file to be unwrapped. It pulls it right in without confusion and there is no need to move the gnomen to the center of the model or to break the calc out to find 1/2 model thickness to get it dead on center. It's worth a look. I've used AC for 10yrs and Aspire's rotary machining tools are vastly superior.

-B

[bob_dodd]

Jim; it looks like you machined it along the indexer axis , have you tried making one rotating model and stepping along the length ?

[jim_vv]

Greetings, Bob

I turned the raster to 0 degrees and the toolpath still appears to be creating a bulbous part. I have attached a screen shot.

Kind regards,

JIM

[bob_dodd]

Jim you could try a go around , import model center it , then do a grey scale so you can see it in 2D , apply bounding box so you only machine the top flat area , make tool path for this ,,, then bring model in again but rotate it before pasteing to get other surface (looks like only 2 ) paste it , do same as above ,,, put part in indexer machine 1 flat surface at a time , rotate it between files this may work

[Brady Watson]

Jim,
If you send me the model (via email goto IBILD.com) I will show you what it looks like in Aspire as a rotary model.

-B