Tapered Rope Carving Help

Topics related to wrapped rotary machining in Aspire or VCarve Pro

Tapered Rope Carving Help

Postby chubb » Tue Feb 04, 2014 6:33 am

Hi,

I'm new to aspire and having some problems trying to do a tapered rope carving on a lathe-turned table leg.

I searched the forum but the closest I got was this thread;

http://forum.vectric.com/viewtopic.php?f=27&t=9483&p=66457&hilit=Tapered+rope#p66457

Which in the end really didn't have a clear solution on how to do a tapered rope carving with aspire on a controlled B-axis lathe.

So the main problem:

I have a 450mm length leg, which is 25mm diameter at one end and 25mm at the other. I have ball nose 3D carving bits and rope carving bits (so any solution using either would be fine).

I just can't seem to figure out how to get a tapered spiral in aspire. I've looked through all the tutorials, but still can't figure it out.

I would really greatly appreciate any advice on how to get this done or even better, maybe, a step by step on how to do it :lol:

Regards,


Mark
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Re: Tapered Rope Carving Help

Postby mezalick » Tue Feb 04, 2014 11:58 am

Using the wrapping feature in Aspire is simply understanding the concept that when a flat item with different thickness’s is wrapped around a center axis you will see a column shape with undulations.
Now, the trick is to get those undulations to match what you want to create.
If you create a wrapped project with a component that mimics the “ undulations “ of the base shape, you can then V-Carve or profile cut the spiral ridges.
You would still need to have a roughing and finishing toolpath before you use the profile toolpath.
This is just one simple way to make this.
I hope it helps.

Michael
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Re: Tapered Rope Carving Help

Postby dealguy11 » Sat Feb 08, 2014 3:16 pm

Mark - you'll need to do one of two things to make a tapered rope spiral with Aspire. Aspire will not control your B axis - it doesn't have the ability to generate code for it. So, your choices are:

1. (Takes the most time) Generate the vectors for a rope toolpath with the Spiral Layout gadget, then the toolpaths using a rope cutter cutting a profile on the vectors. Preview this toolpath, and save the preview image as a component. Then, create a smooth tapered component using a 2-rail sweep, as Michael suggested above. Add the rope toolpath component to the tapered component, adjusting height of the tapered component as necessary to get it to the right radius. Toolpath again with a ballnose cutter and use this toolpath to actually cut it (this approach will work for machines that do not have a tilting table). Unfortunately, you can't just use a rope cutter to do the actual cutting in this option because the trailing edge of the cutter will dig into the work as it goes down the taper.

2. (Takes least time, but requires you to write a tiny amount of G-code). Generate the vectors for a rope toolpath with the Spiral Layout gadget, then the toolpaths using a rope cutter cutting a profile on the vectors. Save this toolpath as a g-code file for cutting. In a text editor, open the g-code file and insert one line of code after the header block to move the B axis to the appropriate height. You will need to calculate this yourself - will take a little trigonometry. In Mach3, the code would look something like "G90 G0 B0.5" where the number following B is the number of inches (or millimeters if you're in metric) you want to move the B axis. You should probably put another line of code toward the end of the program to move the B axis back to 0, i.e., "G90 G0 B0"

The difference in cutting time is hours for option 1 and a few minutes for option 2.
Steve Godding
D&S Artistic Woodworking http://www.dsartisticwood.com
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