Wrapping toolpath question

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Gasawdust
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Wrapping toolpath question

Post by Gasawdust »

Am new to wrapping and Aspire in general.
To test my new (cheap Chinese) rotary axis I designed a simple tapered cylinder file using the wrap setup and a two rail sweep. All looks ok in the preview so I made a toolpath file using the Mach2/3-Wrap X2a Post processor. Ran the cut and the rotary axis would start at A0 and wind up to A355 while cutting the taper and the go to safe z and rotate all the way back to A0 before plunging the Z and starting another cut. I know I could increase my step over and cut depth of pass to reduce some of the code and time but the long and the short of the question is this normal for the wrap feature? This is a fairly simple cut that has over 7000 lines of code and takes 4x the amount of time to perform on my lathe.

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dealguy11
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Re: Wrapping toolpath question

Post by dealguy11 »

1. Yes this is normal behavior. Aspire views the surface of your wrapped item as a flat rectangle. The toolpath behaves exactly as it would on a rectangle - i.e., when it gets to the end of the rectangle, it goes back to the start for the next pass. There are ways to trick it into doing a continuous path, but they are not straightforward.
2. It is normal that it takes longer to cut a tapered cylinder on the rotary than on your lathe. You'll get a better finish on the lathe, too. The thing you gain with the rotary is the ability to do things like carving and spirals.
Steve Godding
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mezalick
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Re: Wrapping toolpath question

Post by mezalick »

Please let me add...
Steve has done his share of rotary and has shared his finding to everyone here on the forum.
I am one who has benefited from his knowledge..
Do a quick search of "continuous cutting " and read what Steve has posted....
Very smart guy there..!!!

Thanks Steve.

Michael
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Gasawdust
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Re: Wrapping toolpath question

Post by Gasawdust »

Thanks guys, i’ll Some more studying. The Vectric tutorial on wrapping is good but i’m a slow learner when interested in only a few current salient points.....too much to absorb in the video.

Gasawdust
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Re: Wrapping toolpath question

Post by Gasawdust »

By the way....do either of you know anything about a software product called CNCwrapper. I tried the website cncwrapper.com but it seems to be down. Not sure if they are still in business or not. I’ve seen some positive reviews but not sure if their product provides a wrapping toolpath any better than Aspire.

Thanks again,
Tom

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IslaWW
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Re: Wrapping toolpath question

Post by IslaWW »

Tom...
In many cases those "wrapper" programs simply take the code you would put out in your Vectric software and add the rotary degrees or add feedrates so it can run on Gcode machines, as Vectric products do not put out a rotary feed
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Re: Wrapping toolpath question

Post by 4DThinker »

There are two other way to make tapered cylinders. One is to use the moulding toolpath which steps over and keeps cutting on the return path, as it steps down the cylinder. The other is to use the fluting toolpath and a parallel array of vectors that start at the top (big end) and end at the small end. You can also make them more efficient with a vector that runs toward the bottom, steps over, then runs back to the top. An array of either single segments or those returning vectors will cut all around the cylinder, completing the taper, before spinning back to the origin.

4D

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IslaWW
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Re: Wrapping toolpath question

Post by IslaWW »

As stated above there are numerous ways to accomplish this task which is fairly simple. The reality is that in most cases, If it can be accomplished on a lathe, it will always be much quicker. 4 times as quick is about as good as it gets, some take even longer on a rotary.
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dealguy11
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Re: Wrapping toolpath question

Post by dealguy11 »

The Vectric software does pretty much exactly the same thing as CNCWrapper used to do. It wraps a flat model around a cylinder.

You can speed things up a little if you use large bits, assuming both your spindle and your rotary stepper have the power to handle them. If you're just making a cylinder without a taper, then a large flat-bottomed surface planing bit like the Magnate 2704 works well. For a tapered cylinder I'd probably use a large core box bit - 1" or 1.25". Again, your spindle needs to be powerful enough to turn these bits without bogging down.

Either of the techniques discussed above (fluting toolpath and moulding toolpath) will work, along with the more "traditional" way of doing it using a component. If you want to do anything more elaborate than a taper, you'll probably need to get into creating components for the shapes. You can use the fluting toolpath to give you a taper, continuously turning the rotary axis. You have to make the toolpath run diagonally from the thick end to the narrow end, and the length of the toolpath will be very long, i.e., many multiples of the project length or width, depending on the orientation of your rotary axis. The length of the toolpath will be the dimension of the axis that wraps around, times the number of revolutions required to give you the stepover you want. The improvement in cut quality is noticeable, but I would probably just use either a component or a moulding toolpath as they are much simpler to set up and you're going to have to sand it anyway (the finish will still not be lathe quality)
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Re: Wrapping toolpath question

Post by TReischl »

Like the OP I am not keen about watching work get slowly roughed on the rotary when I have a machine that does it way faster right next to it. Here is a project I am currently working on:
20180322_082405_1521750709282.jpg
20180322_082416_1521750709087.jpg
What I did was design the shape in CAD. Then I went to the lathe and roughed it out leaving some extra material for the rotary. This way I could just go to a finishing toolpath right off the bat.

I like to do hand carving with both hand tools and power carvers. So that set up you see in the pics is very handy. I can move between the lathe, rotary axis and the carving vise without ever removing the piece from the jaws. When I am done carving the leaves it will go back on the lathe to finish shaping the base area of the piece. The rotary was extremely handy creating the leaf shapes and removing the background.

We all do it, get a machine and pretty soon we find ourselves spending a lot of time trying to figure out how to make it do everything. I used to cut rectangular shapes out on the cnc until I realized I could do it faster on the table and radial arm saw and not try to figure out what to do about machining marks on the edge of the piece.
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