QCAD.org Forum

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

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.

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.

Hi,

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


second arc R=0.75 - YES trim


Done!

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

You're welcome!

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

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.

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 Arc@ TTR I proposed the Circle@ TTR and trimming.
In the meanwhile we learned that rounding without the option trimming is in fact Arc@ 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 + Circle@ TTR or Arc@ 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