Changing diameter of rotary carve when using STL Importer

[Bigtyme]

I have been reviewing the tutorials for the Rotary Carver using the STL importer and I have a question. It seems that when you import an STL into the rotary software (a chess piece, for example), no matter what diameter you design the piece to, the blank diameter is always set at 4.25 inches. Does this mean I would have to load a 4.25" diameter blank even if I was carving a 1.5" diameter rotary piece such as a chess piece. Maybe I am just missing a simple adjustment, but I can't seem to find it. Any help would be greatly appreciated....

[mtylerfl]

John,

For STL imports as a rotary job, the default is always going to be the max. diameter (i.e., the 4.25"). It is a little confusing, but no, you do not need to load a material of that diameter - it can be smaller. You will see the rotary carving air for quite some time until it ultimately reaches the material and actually carves into it. Slightly annoying to watch it "waste time" carving air, but this was the method chosen to make sure the STL import carves correctly.

[Bigtyme]

Thank you for the information, Michael. I am glad it won't require the larger diameter piece. I know the importer lists a minimum diameter which I had hoped would work. I guess the "air" carving time will be a little wasteful, but not as much as a 4.25" diameter blank for a 2" diameter piece. Thank you again for the clarification. Much appreciated. I have had the rotary jig and software for a bit, but have been swamped with other projects. Hope to soon try some rotary lithos as well as some chess pieces....

[bergerud]

I remember that there is a way to choose the dowel diameter at the keypad.

[Bigtyme]

Quote " I remember that there is a way to choose the dowel diameter at the keypad." Quote

Any idea where I could find more info on this, Dan??

[mtylerfl]

Watch the Rotary Jig Software tutorial - STL Importer video on the following webpage:

http://www.carvewright.com/support-page/getting-started/tutorials/accessory-tutorials/rotary-jig-tutorials/

At about 5 minutes in, Joe explains the 4.25" diameter which was derived from the STL rotary import. Do not change your project dowel diameter UNLESS you also make adjustments to the depth of the pattern (i.e., your STL rotary import) to allow it to wrap around properly.

You always choose the diameter of your stock at the machine...nothing unusual about that - it is part of the project setup already. So, you can change that diameter to an appropriate size for the project as well as the actual stock, but I believe you will still see air carving based upon the max. diameter of the STL rotary import (4.25") if you kept the size the same as when you imported it in the first place, regardless of your dowel diameter setting at the machine.

I am open to correction if this is not true. :)

[bergerud]

I am now at work! I will play with it when I get home. I just remember that there are dowel diameters in steps of 1/4" or 1/2" to choose from. I cannot remember the context of it.

What I have tried with the stl imports, is: Start a new rotary project with the dowel diameter, say 2", that I want. Copy and paste the pattern onto the new project. Calculate and rescale the pattern to the new length (new circumference 2Pi) and the new depth (old depth -(4.25-2)/2 = old depth - 1.125).

[Bigtyme]

Good info, Michael...thank you....I have watched the tutorial a number of times, but will pay closer attention to that segment. I didn't quite understand it before, but your info certainly helps. thank you...

[mtylerfl]

I am now at work! I will play with it when I get home. I just remember that there are dowel diameters in steps of 1/4" or 1/2" to choose from. I cannot remember the context of it.

What I have tried with the stl imports, is: Start a new rotary project with the dowel diameter, say 2", that I want. Copy and paste the pattern onto the new project. Calculate and rescale the pattern to the new length (new circumference 2Pi) and the new depth (old depth -(4.25-2)/2 = old depth - 1.125).

Yes, you set the diameter at the machine to the nearest/greater diameter of the stock in .25" increments. This is the normal setup procedure outlined in the Rotary PDF instructions.

Yes, IF you copy/paste a ptn created from an STL import to a new project, you have some freedom to create a new board thickness/diameter to accommodate the ptn to avoid too much air carving (although this might result in the project result becoming distorted and/or size change). However, a "straight import" of an STL into a rotary project will always default to the 4.25" diameter and result in air carving if the object is smaller in diameter than the 4.25".

[bergerud]

(although this might result in the project result becoming distorted and/or size change)

Now that you mention it, I think I also had to recalculate a new height as well. I will have to go through it again. It can be done without any distortion.

edit: I think : new height=(old circumference/new circumference)*100 (the 100 is the old height)

[mtylerfl]

Now that you mention it, I think I also had to recalculate a new height as well. I will have to go through it again. It can be done without any distortion.

I did something similar with an imported STL egg model I created then imported. I copied/pasted into a new project and played with the height and depth settings quite a bit to be sure it still came out looking like an egg! (I think I had to use a 999 Height if I recall).

I did end up with a 'mysterious' uncarved line around the largest diameter area of the egg, though. It was explained to me that this was caused because I created keepout zones (zero carve regions) that (of course) were even with the top surface of the board. The largest diameter of the egg was shy of the surface by a small amount. Because this was a square blank (i.e., not rounded first), the zero carve region was observed and created that line around the egg's largest diameter which was a tad lower from the surface. This behavior is a deliberate choice because the alternative would have been that the jig would only accept round dowels instead of both square stock AND round stock.

So, when playing with Height and Depth settings to avoid or workout ptn distortion, the screen preview might appear "clean", but it's possible the actual carve might have some unintended raised areas that need to be sanded away. The alternative is to allow the 4.25" default and put up with some air carving.

[bergerud]

I works fine for me but I calculate all the new values.

[mtylerfl]

I works fine for me but I calculate all the new values.

Excellent. Glad it's working!

[mtylerfl]

I did something similar with an imported STL egg model I created then imported. I copied/pasted into a new project and played with the height and depth settings quite a bit to be sure it still came out looking like an egg! (I think I had to use a 999 Height if I recall).


I just checked my rotary "egg project" settings on the egg ptn...I did not change the Height setting. I left it at 100.

[bergerud]

If one wants to create a rotary mpc with a given dowel diameter D (Here comes a little math!) using a rotary pattern output from the stl importer, it can be done. The y of the rotary pattern does not have to be changed. The x length as well as depth and height do need to be changed. The original x length from the importer will be 13.359 (circumference of 4.25 diameter dowel = 4.25 Pi = 13.351). It needs to be changed to the circumference of the new dowel. The depth has to be changed as it will not be as deep in the smaller dowel. When the x length of the pattern is reduced, the height will also reduce. The height needs to be returned to original.

Here is the procedure I have used:

1. Copy the pattern from the mpc that the STL importer created and make note of the depth of the pattern.
2. Start a new rotary project with the dowel diameter you want (lets call it D).
3. Paste the pattern. (It will be too deep and too long but continue.)
4. Change the depth to the new depth = old depth - (4.25 - D)/2. (old depth - 1.125 if D = 2)
5. Uncouple the x y sizes by opening the lock between the edit boxes. Change the x from 13.359 to the new dowel circumference = Pi D. (6.283 if D = 2)
6. Restore the height back to original by changing the 100 to (100)(4.25)/D. (212 if D = 2)

That should do it. The object should appear undistorted on the smaller dowel.

[Bigtyme]

Great information, Dan and Michael. Thank you both for the lessons. I know it will be reviewed many times by fellow CW users....especially me :) ....

[mtylerfl]

Dan,

Thank you very much for that. Your procedure is extremely useful and helpful to all of us for our rotary projects!

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John,

You are welcome. I'm so glad we have Dan here. He is a math wiz! I don't think there is much he can't figure out.