SOLVED. Tangential Arc drawing off of another arc.

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Camzl1
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SOLVED. Tangential Arc drawing off of another arc.

Post by Camzl1 » Wed Aug 07, 2019 10:46 pm

I use a CAD/CAM program called DDX Easystone in addition to QCAD, and in their software, it has limited cad tools but the ones it does have are simple and powerful at the same time. In the attached dxf file of a traditional countertop drawing, I am trying to draw two arcs that connect tangentially. One is made using the fillet command on the bumped out portion (easy) and the other is an arc that is drawn using snaps of tangent to tangent. QCAD is working different here in this regards and I understand the Tangential snap is NOT designed for this. I want to know about, what I have found to be the closest thing to what I am used to, (Tangent, Point, Radius) is the right direction for me. This command works great until the end. It allows me to select the intial Arc (3/4' radius in dxf) and displays the appropriate circle based on the value i gave it in the dialogue box (3). So far so good. Then I want to snap it to tangent to the straight line that is parallel to the front line. This is where the only snap that works, as I envison, is (on-entity), and it gets me oh so close, but not exact. I need guidance on how to do this. The previous software I was used to using, has a tangential snap that works with lines and arcs.

QCAD/QCAM 3.21.3
Attachments
selction not possible for exact.png
selction not possible for exact.png (135.52 KiB) Viewed 2886 times
Tangential Arc-Point-radius.png
Tangential Arc-Point-radius.png (12.57 KiB) Viewed 2886 times
Tangential Arc off of arc.dxf
(102.55 KiB) Downloaded 128 times
Last edited by Camzl1 on Thu Aug 08, 2019 12:51 am, edited 1 time in total.
Best Regards,

Eric Pate
CNC Technical Director
Terminator Diamond Products, Inc

https://www.terminatordia.com/

CVH
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Posts: 421
Joined: Wed Sep 27, 2017 4:17 pm
Location: Belgium; Antwerp

Re: Tangential Arc drawing off of another arc.

Post by CVH » Wed Aug 07, 2019 11:51 pm

Your goal is to draw a circle
-Tangent to the horizontal line
-Tangent to the smaller radius
-having a Radius of x.xx

Why not try Circle 2Tangent Radius or CTR and
choose one of the solutions?

But I thought I had a better one.
If the countertop was a poly.
Just 'Round' with radius and trim.

But no, and that is a bug.

Camzl1
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Posts: 22
Joined: Wed Nov 28, 2018 4:56 pm
Location: North Carolina

SOLVED Re: Tangential Arc drawing off of another arc.

Post by Camzl1 » Thu Aug 08, 2019 12:50 am

Thank you CVH. That worked just fine. I was so focused on an ARC function I didn't even think to look in Circles. I can handle exploding and trimming as desired.
Attachments
Circle-Tangent-Point-Radius.png
Circle-Tangent-Point-Radius.png (18.62 KiB) Viewed 2871 times
Best Regards,

Eric Pate
CNC Technical Director
Terminator Diamond Products, Inc

https://www.terminatordia.com/

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Husky
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Re: Tangential Arc drawing off of another arc.

Post by Husky » Thu Aug 08, 2019 12:58 am

Hi,

I would use the "Round" tool,
launch the tool,
first arc R=3 - NO trim (trim depends on the situation!)

Husky-2019.08.07-01.png
Husky-2019.08.07-01.png (87.29 KiB) Viewed 2867 times

second arc R=0.75 - YES trim

Husky-2019.08.07-02.png
Husky-2019.08.07-02.png (84.68 KiB) Viewed 2867 times

Done! :wink:
Work smart, not hard: QCad Pro

If a thread is considered as "solved" please change the title of the first post to "[solved] Title...". Thanks!

Camzl1
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Posts: 22
Joined: Wed Nov 28, 2018 4:56 pm
Location: North Carolina

Re: SOLVED. Tangential Arc drawing off of another arc.

Post by Camzl1 » Thu Aug 08, 2019 1:35 am

Thanks Husky. That is how AlphaCam works and does it. Didn't think to try that either. That is even faster.
Best Regards,

Eric Pate
CNC Technical Director
Terminator Diamond Products, Inc

https://www.terminatordia.com/

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Husky
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Re: SOLVED. Tangential Arc drawing off of another arc.

Post by Husky » Thu Aug 08, 2019 1:47 am

You're welcome! :wink:
Work smart, not hard: QCad Pro

If a thread is considered as "solved" please change the title of the first post to "[solved] Title...". Thanks!

CVH
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Re: SOLVED. Tangential Arc drawing off of another arc.

Post by CVH » Thu Aug 08, 2019 2:56 am

Ok I posted somewhere in between and it isn't posted....

Husky,
Your first steps 1-5 rounds line and ortho line R3
Your second steps 1-4 rounds the 3th line to the new Arc R0.75
This rounding is not the same rounding as the original

Tested all roundings see file
The two bottom ones fail

Win7pro Qcad3.23pro wininstaller
Attachments
Rounding Line-inbetween-Arc.dxf
(129.05 KiB) Downloaded 137 times

Camzl1
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Posts: 22
Joined: Wed Nov 28, 2018 4:56 pm
Location: North Carolina

Re: SOLVED. Tangential Arc drawing off of another arc.

Post by Camzl1 » Sun Aug 11, 2019 3:10 am

CVH. You are right. The results are two different solutions. The first one is tangential, the other way as Husky suggested is just a trim of two congruent arcs. I tried rotating the result to make it fit on top of the existing two arcs drawn with Tangent Circle tool. It was close but not and exact fit. I would love to know what is the difference if someone could answer that one. I know which one I need to use, just want to know about the behavior between the two.
Husky way vs CVH way.png
Husky way vs CVH way.png (22.78 KiB) Viewed 2791 times
Husky way vs CVH way-rotated.png
Husky way vs CVH way-rotated.png (23.85 KiB) Viewed 2791 times
Best Regards,

Eric Pate
CNC Technical Director
Terminator Diamond Products, Inc

https://www.terminatordia.com/

CVH
Premier Member
Posts: 421
Joined: Wed Sep 27, 2017 4:17 pm
Location: Belgium; Antwerp

Re: SOLVED. Tangential Arc drawing off of another arc.

Post by CVH » Sun Aug 11, 2019 9:46 am

Camzl1,
First,
Rotating a tangent around it's tangent point it will become non-tangent.

Take a look at the more elaborated version of my file.
Top illustrations.
You asked for a tangent arc with radius between line A and arc B.
You will be limited to certain minima constraints because not all radii can.
As there is no function [email protected] TTR I proposed the [email protected] TTR and trimming.
In the meanwhile we learned that rounding without the option trimming is in fact [email protected] TTR.

The 2 step solution is for a diffetent approach.
Drafted with right angles there are two pathsways:
-1 You need the rounding with 0.75 for some reason exactly on the protruding corner and then you want to put another larger rounding.
-2 You need the rounding with 3 for some reason exactly inside the corner in 'the back' and then you want to round this with 'the front'.

The solution for 1 is yours + [email protected] TTR or [email protected] TTR or Round(notrim)
The solution for 2 is Husky' s 2-step

We would expect that setting the trim option would do the trimming for us.
But that doesn't allways work out well.
I tried several variations and added the various results.
The file is intended for a bugreport.
The scope is yet too narrow and we have to look at the bigger picture before filing.

Regards
Attachments
Rounding Line-inbetween-Arc.dxf
(138.39 KiB) Downloaded 149 times

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