Rounding Toolpath Error

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rwebcon
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Rounding Toolpath Error

Post by rwebcon »

I tried looking for similar questions on forum but no luck.

I’m trying to run my first rotary job but keep getting error message I can not explain. All I want to do is take round material 1.25 in Diameter and remove about .01 of the material just to get some experience using Rotary. If I change the tool from a .125 endmill to a .25 endmill I do not get an error message. I cannot figure out why it would make a difference using different endmills with only .125 difference in diameter. I need to better understand how this works for future applications.
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Error Message on Rounding.JPG
Rounding setup.JPG
Rotary .crv3d
(663 KiB) Downloaded 22 times

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Rcnewcomb
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Re: Rounding Toolpath Error

Post by Rcnewcomb »

With the rounding gadget the blank must be the same size or larger than the diameter of the rotary job. The idea is that I am talking some raw material (square or round) and reducing it down to the diameter I need for my job.

If I want to leave a bit of "skin" on the blank then the blank HAS to be larger than the rotary job diameter. I may tell the rounding toolpath to leave a bit extra "skin" rather than carving all the way to the final diameter. In my example below the job has a 1.25" diameter. I am starting out with a raw blank that is 1.3" in diameter. I'd like the rounding toolpath to leave a skin of 0.01" so the toolpath would leave the blank at 1.26" diameter.
Rounding.JPG
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adze_cnc
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Re: Rounding Toolpath Error

Post by adze_cnc »

As if rotary jobs aren’t convoluted enough this toolpath doesn’t do anything to make things clearer. From what I understand to get what the original poster wants he’ll need to:
  • set the diameter of the cylinder in the job setup to be 1.24” (what he wants it to be)
  • in the toolpath choose a round stock with diameter 1.25” (what it currently is)
  • set allowance to 0” as he doesn’t want to leave any extra material but does want to take things down from 1.25” to 1.24”
The original setting failed because the job and toolpath settings were the sane 1.25” and he wanted to leave an extra 1.24” on top of that making the blank needing to be 2.49”.

rwebcon
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Re: Rounding Toolpath Error

Post by rwebcon »

Thanks again everyone help. Starting to make sense now.

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Rcnewcomb
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Re: Rounding Toolpath Error

Post by Rcnewcomb »

Eventually you may find that it is faster and easier to use a pocket toolpath to round the blank rather than the rounding gadget.

I typically use a 1/2" end mill which works fine for rounding 4"x4"s.

YMMV
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rwebcon
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Re: Rounding Toolpath Error

Post by rwebcon »

Yes, pocket may be the way to go. I did get the gadget to work by the way. Looked on web but could not find any examples of pocket toolpaths for rounding..

My solution to finding depth of cut on corners.
For a 4-inch square block 2 times square root of two minus the radius of the enclosed circle should
Give depth of cut. I would use the boundary box as the area to pocket. Do you use raster milling with your .5 endmill?
I’m I close to figuring this out?
Any examples on the forum. I looked but may not have the correct search works.
Thanks

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Rcnewcomb
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Re: Rounding Toolpath Error

Post by Rcnewcomb »

Do you use raster milling with your .5 endmill?
Yes, I raster along the length of the blanks rather than around the blank. That is my personal preference.

If you have a table saw or a band saw it may be less stressful to use that to trim the corners off the square blank.
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Screen Shot 2022-05-26 at 1.35.23 PM.png
- Randall Newcomb
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SteveNelson46
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Re: Rounding Toolpath Error

Post by SteveNelson46 »

The method I use is a combination of the rounding gadget and the spiral gadget. Use the rounding gadget, any method, to get the diameter to within about .125 inches of final diameter. Then, use the spiral gadget to get the exact diameter. In the example I used a single spiral and a spacing between strands of .5". The spacing must be less than half of the tool diameter. I used a 1.25 surfacing bit. Keep in mind that no matter what method you use the z zero MUST BE SET EXACTLY AT CENTER OF ROTATION. Otherwise the error distance will be magnified by 2. If it is done correctly, and the correct bit, feed, and speed is used, the final results will be very smooth.
Attachments
Spiral Rounding 2.5 Dia.crv3d
(670.5 KiB) Downloaded 26 times
Spiral Rounding 2.5 Dia.crv
(171 KiB) Downloaded 23 times
Steve

rwebcon
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Re: Rounding Toolpath Error

Post by rwebcon »

What are people using to hold square stock in a 3" chuck when the stock will not fit?

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Rcnewcomb
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Re: Rounding Toolpath Error

Post by Rcnewcomb »

There are a few options:
You can screw something on the end for the headstock to grab.

I screw a small round piece to the 4x4 or two 2x4s
Screen Shot 2022-05-28 at 1.45.07 PM.png
These indexing hubs can be purchased from Legacy Woodworking.
Screen Shot 2022-05-28 at 1.48.26 PM.png
Our you can chop down the end of the material to fit.


- Randall Newcomb
10 fingers in, 10 fingers out
another good day in the shop

rwebcon
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Re: Rounding Toolpath Error

Post by rwebcon »

Made a 3D part to attach to material. Center hole helps find center of material using a center punch to guide you.
This is a other software model.
Material Capture View2.JPG
Material Capture View1.JPG

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