How To: Continuous Rotation & Indexing

Topics related to wrapped rotary machining in Aspire or VCarve Pro
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Rcnewcomb
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How To: Continuous Rotation & Indexing

Post by Rcnewcomb »

This is a technique that Milo Scott showed me.

It allows for continuous rotation while indexing. For some designs this technique is much faster. ->Video Example
For other designs is may be slower than standard 3D Rough/3D Finish.

I've attached Milo Scott's PDF file describing the steps in detail.

TL;DR
  1. Set up a rotary job with a 3D design
    Screen Shot 2022-09-12 at 3.47.01 PM.png
  2. Select the spiral layout gadget.
    Screen Shot 2022-09-12 at 3.48.17 PM.png
  3. Set the Spacing between strands to the stepover for your ballnose bit. In this example I am using a 0.125" ballnose bit and want a 10% stepover. The spacing between strands is 10% of 0.125 = 0.0125.
    Screen Shot 2022-09-12 at 3.49.36 PM.png
    In my example it says Total Number of revolution for spiral = 2236.99
  4. Select the vector that was created from the spiral gadget.
  5. Choose the Profile Toolpath.
    Set the cut depth to 0
    Profile On the vector
    Check Project toolpath onto 3D model
    Screen Shot 2022-09-12 at 4.12.10 PM.png
Now it will cut the project with continuous turning. Like a 3D finish toolpath it will NOT use the pass depth.
Attachments
1001 Vectric Continuous Turning Round 27 Mar 2021.pdf
(649.86 KiB) Downloaded 488 times
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Re: How To: Continuous Rotation & Indexing

Post by Jimcad »

Thank you Randall,

That's VERY interesting. Way above MY pay grade but VERY interesting.
Just moved house and swamped with a list from Mrs. Jim but one day I'll give it a go. :wink:

Jim

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Re: How To: Continuous Rotation & Indexing

Post by PaulB »

What a great idea to add the design to the vector.
I use the continuous turning method on most of my rotary jobs, but this takes it to the next level.
this is a "got to do soon" item on my short list.
Thanks

Paul.

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Re: How To: Continuous Rotation & Indexing

Post by SteveNelson46 »

Randall,
Thank you very much for this information I try to learn something new every day. and this method of carving 3D with continuous rotation certainly fits the bill. Now I'm trying to figure out how to use it on some of my projects. Thank you again for the information and inspiration.
Steve

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Re: How To: Continuous Rotation & Indexing

Post by Jimcad »

Ditto what Steve just said.
Although I've never used my 4th axis yet.
One Day ! ! :D
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Re: How To: Continuous Rotation & Indexing

Post by Rcnewcomb »

Although I've never used my 4th axis yet.
Start with a bunch of 2"x"2s. You can trim the corners on your bandsaw or table saw to save time and lighten the load on your CNC. You may be able to skip the rounding process if the blank is small enough and/or the corners are trimmed off.
Use the largest bit possible: large V-bits with an angle >=90 degrees, ballnose, and form tools are great.
Use the fluting and spiral layout gadgets.

Thew two fluted columns were cut in 3 1/2 minutes at 60 IPM at 0.1" pass depth. The Spiral was cut in 5 1/2 minutes.
Screen Shot 2022-09-13 at 4.57.56 PM.png
This was carved from a 4"x4" in 10 minutes and 35 seconds using a V-bit and the fluting toolpath. Even though it is tapered in the middle no 3D work is involved.
Screen Shot 2022-09-13 at 5.02.06 PM.png
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Re: How To: Continuous Rotation & Indexing

Post by Leo »

Randall, Thank you for that connection.

I checked out Milo Scotts web site and it is extremely informative, He is very professional and quite talented. One that I will bookmark and use for sure. Some interesting youtube tutorials.

I would encourage all to check out his work.
https://lwmcnc.com/

I do appreciate this PDF from Milo that you posted

Thank you
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Re: How To: Continuous Rotation & Indexing

Post by Rcnewcomb »

Further update. I've been comparing toolpath methods. I've carving chess pieces for a King and Queen out of a pine 2x2. I carve one with conventional 3D finishing using a raster toolpath. Machine time was 60 minutes.

I took the same project and used Milo's spiral continuous turn technique. This time the machine time was 13 minutes, and the piece had a better finish. (Bottom piece)
KingQueenIMG_4193.jpg
If you have been frustrated with the slowness of rotary work please try this technique.
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Re: How To: Continuous Rotation & Indexing

Post by Leo »

Randall - once again thank you.

I forgot about this, but the reminder is awesome.

I need to put my rotary axis on the machine and play around with it.
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Re: How To: Continuous Rotation & Indexing

Post by SteveNelson46 »

It works great. Even with twists and modeled shapes. I'll post the final project as soon as it's complete.
Attachments
Candle holder spiral TP.png
Candle holder spiral TP setup.png
Steve

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Re: How To: Continuous Rotation & Indexing

Post by tcoplin »

I have been having difficulty with the Rounding toolpath gadget so I tried the Continuous Rotation & Indexing method referenced here. I wanted to cut a piece of test stock 1.4 inch square with a point to point diameter of 1.98 inches to a final diameter of 1.0 inch. Thus I calculated the cut depth would be 0.99 - 0.5 = 0.49. I used a 1.5 inch surfacing bit. It cut my stock down to a 0.5 inch diameter and left a slight spiral groves rather than completely smooth. Trying to figure out what I have done wrong.
Attachments
7F564E59275F40ECA13ADA589C3B92BD.png
646CA645210E4FB7B033B9E9807EAA06.png
FFB7C6EA032246AE9D44677E85254F12.png

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Re: How To: Continuous Rotation & Indexing

Post by Rcnewcomb »

It cut my stock down to a 0.5 inch diameter
What was your process to ensure the bit was Z-zeroed to match the center of the cylinder?
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Re: How To: Continuous Rotation & Indexing

Post by tcoplin »

I Z-zero first on the surface of the tail stock, move the spindle to the left of the tail stock then go to zero. Then I move the bit tip to -0.522 and Z-zero. 0.522 is the distance from the tail stock surface to the center point.

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Re: How To: Continuous Rotation & Indexing

Post by Rcnewcomb »

Look towards the end of the G code file. (You can use Notepad to look at it.) What values do you see for Z?
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Re: How To: Continuous Rotation & Indexing

Post by adze_cnc »

Randall,

The problem that’s been discussed in the last few posts kind of confuses me. And as I don’t know much about “4th axis” I’m even more confused.
  • the wrapped spiral gadget presumes an underlying 3D model. What if there is no model. How would it react?
  • the wrapped spiral gadget seems to presume a ball end bit. What are the consequences of calculating for a ball end bit but running a square end bit?
  • the poster’s profile toolpath does not have project to 3D model checked. Even if there was a 3D model how would that come out?
Steven

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