Guitar LP dxf problem and some other question

[takeitslow]

Hello to all,
It's been a while but here I come again with some things I would need some help for.

I spent a lot of time drawing a LP guitar so as to try and have it "built" by my CNC. As I don't use any Rhino or Fusion or Cad, that part was real time consuming for me, going back and forth, bying mdf "wood" and drawing some changes... but I've come up finally with something I like.

I've succeeded in having a "first try template" cut by my CNC, that's the "LP Guitar template" in cb and nc I'm posting here.

From there, from that template file, I needed to cut the curving template just in case I wanted to buil a handmade LP.

I made for instance "Lp template 4th thickness" and had it cut with success in some mdf. I'm posting it here in case you wanna see. Other worked too but not the "LP template 5th thickness".

I took a picture of what my linuxCnc shows. And before realising that something wrong, while as I was still sitting in front of my computer drawing, I imagined a way to make some steps for my curves. I would need still to do the curves by hand as I don't know, sadly, how I could make cambam doing the curves for me.

If we consider the cambam "LP carving" file, the more important polylines are 202,204,206,207,208 and 209. Those are the steps. That's also the ones you see in "LP guitar template" file...

For instance, on the 202 polyline, going towards the 204, we are - 1.178 mm (- 0.0464") below the center part at level 0. I added some secondary polylines from one important to another one as my tool is only 6mm in diameter.

But as you can also see in the picture I'm sending, something's wrong too (looks like the same problem in thicknes 5).

I made about 10 tries changing one line or another, "cleaning the polylines" or "arc fit" or "remove overlaps", changing the Z too but I couldn't make it work.

You already helped when I wanted to use my Cnc for a thinline Telecaster so if you're still willing to help, that'd be gratefully appreciated.

First question: What is wrong? Why can't "LP Carving" and "5th thickness" work like "template" and "4th thickness"?

Beside that first question, I'm sure some of you know how to make it work better.

For instance, normally the maple cap on the LP is about 0.593" thickness (1.50 cm) and me, so as to make that steps, I start from the top. That's where my "X-Y-Z" starts. But if my maple cap is thicker, should we even consider that everything is dead flat, if I only go with the - steps, my final step will be thicker than the 0.235" (5.96mm) I need.

So, how could I make the machine work from the flat martyr I have (I surfaced it). Is there a way to say to the machine "I start from martyr 0". "And we go up. All the way up. And when you've reached the final step, you finish the final surfacing with level 1.50cm"...

I don't know it it's completely clear but I hope it is...

And another question, about the curves, is there a way to make some nice curves from one important polyline to another so as to save me a lot of hand work...

Thanks in advance.

Regards

[takeitslow]

And the problem child ... nope! files

[takeitslow]

I'm sorry for my 3 posts but it's all because the restrictions...

here's the error I have (the 3 first pictures).

The 4th picture is the "template" that just worked fine.

Thanks again!!!

[pixelmaker]

CamBam creates extremely accurate and small arcs.
These circles occur when the control software cannot process these small arcs. It is actually sad that there are still such limitations today.

In CamBam you can set the "minimum arc lenght" in the postprocessor to a larger value.
Default for "minimum arc lenght" is 0.0001
Setting it to 0.001 should fix the problem.
Shorter arcs will then be converted to straight lines.

ralf

[takeitslow]

Dear Ralph (pixelmaker)

Thank you so much!!! I created new nc files after changing the minimum arc length to 0.001 and it worked just great!!!

After a little more than 2 hours I have that first steping try that tells me that I can do it on wood.

Yet, if someone comes along with an idea for rounding these steps, carving or curving or whatever...

Cheers

[dave benson]

 I would need still to do the curves by hand as I don't know, sadly, how I could make cambam doing the curves for me.

There’s a drawing object called a spline, which makes curves that are not arcs.
To make the stepping between your lines defining your layers of equal size, you
can use the offset function in the edit menu, then move each new polyline to the Z height
required. See pic.

If plan on making some more guitars in the future, then this looks like one of those jobs where a
3Dmop + a 2D mop might be an attractive choice.
setting up the job in the way you have would result in a lot of hand finishing.

I downloaded a Stratocaster 3d stl  (with the right dimensions apparently) and applied a 3D mop, see pic.
You can do it all in 2D and it will be faster off the machine, albeit a lot more hand finishing.

In the CB file I’ve two surfaces, one 3D mop for outer shape and one which was used to
make the 2D pockets, and a Dril mop. I’ll post the CB file just as an example so that you can
see the method of masking out areas ‘not to cut’ by masking then out with a Region.

Dave

[Dragonfly]

You definitely need a 3D surface to get smooth transitions.
BTW, the guitar body outside curve does not lie on a single plane. If you tilt the view you will see it yourself.
One approach to get a 3D object is what Dave suggested.

I did a quick and dirty try with the Sweep-2 plugin. The so called 'two rail sweep' method. I made a half contour of the whole body. Then mirrored it along the Y axis with 'Num Move' plugin. Thus getting two symmetrical 'rails'. Then drew a simple cross section curve in the same manner. Used the Sweep-2 plugin to create a 3D object. There are options to play with in the plugin. As well as the cross section shape.

[takeitslow]

Dear Dave and dragonfly,

Thanks a lot for your replies.

I went through them, some with success and some without

First, I selected all my polylines and changed the Z value so as they are all Z=0. I guess that's what was considered as not laying on a single plane, right?

And for all the rest, I've just failed...I used the offset function and gave another "Z" height to those new polylines. But then, just couldn't use the spline thing so as to see what it'll look like... Don't understand how to make it work. I guess I have to spend a lot more time on trying to understand the Strat file too (I've tried but couldn't see the body outline)...
I've also downloaded the weep2 plugin. And guess what? Couldn't make it right with it either...

I would need some learning cambam classes... In 2058?

Anyway, thanks again for your kindness.
All the best

[dave benson]

It’s a steep learning curve at the start, don’t get too discouraged.
This might help with the offset lines.
I’ve only included the polylines and mops required to show how the polylines
are spaced and the settings for the stock surface and target depth.
I moved the polylines about with the numerical move plugin.
In the sim you can see what they look like.
More of, and closer spacing of the ‘offset polylines’ will give a smoother surface.
In the pic you can see I’ve clicked on the 3D mop and the surface and ploylines that
make up the region associated with mop are highlighted.

Dave

[EddyCurrent]

You can download Les Paul 3D files here for free; https://grabcad.com/library?page=1&time=all_time&query=les%20paul#!
Then the top can be cut in CamBam using a 3D machining operation.