Downward Inclining Line HELP!

[shopbotgirl]

Ok, I'm just trying to create a simple line, like a trough, to go around the edge of a piece of plywood. It needs to be 1/8" at the ends and slop down to 1/4" in the middle. Am I missing something easy? I can't figure out how to do this. Any help would be much appreciated... thank you!

[mrdovey]

If the starting point of your line is (&X1,&Y1) and the other end is at (&X2,&Y2) and the surface of your plywood is at &Z, then starting with the bit at a safe height:

J3 &X1,&Y1,&Z + 1/8
MZ &Z - 1/8
M3 (&X1 + &X2) / 2,(&Y1 + &Y2) / 2,&Z - 1/4
M3 &X2,&Y2,&Z - 1/8
JZ &Z + 1/8

should do what you want.

[jsfrost]

Victoria,

I don't completely understand your goals. Do you want a variable Z beginning at Z=.125 dropping down to Z=.250 at line center, and then slopeing up to Z=.125 at the far end? Or is it the width that changes? Is the line straight or curved?

What software are you using?

[shopbotgirl]

Hi Jim,

It's a straight line, starting at .125 on either end and meeting in the middle at .250. The width is fixed at .250 with a drain hole in the center of the line.

I modeled the whole thing in 3d Studio Max and then imported it in to PartWorks3D, however, PartWorks is trying to tool the entire top of the model instead of just doing the line. I don't know what to do about that and I figured there must be an easier way to do it that I just didn't know about yet!

Like I said, any help would be very much appreciated and thanks for taking the time to help me get the straightened out.

Victoria

[myxpykalix]

It kind of sounds from the description like a "fingernail flute" type of design. It might help if you could post a picture or a screenshot of what you are trying to do.

[ljdm]

Not familiar with Partworks, but is there an option when creating toolpath to select the whole model, or just the selected vectors you want cut?

[shopbotgirl]

I took a screen shot... here is the link.

http://www.Renaissance-The-Rebirth.com/lineproblem.jpg

The two lines on the side need to be 1/8" as long as it's on the x axis then once it turns to go along the y it needs to start sloping down reaching 1/4" at the center arrow.

Thanks so much,
Victoria

[jsfrost]

Virginia,

Morris has the method, with no special software needed, just standard Shopbot code. When M3 executes, the tool moves in a straight line from the present position to the commanded position. So, with Z in air (say 1 inch), execute a move to one end of the line: M3, X1, Y1, 1. MZ to the start depth: MZ .125. Then M3 to midpoint at final depth: M3, X2, Y2, .250. Next do the up slope: M3, X3, Y3,.125. And pull the z to safe height: MZ, 1. All this is edited into a new .SPB file, or is edited into an existing file that is doing other parts of your project. It will also work from the keyboard. Use a bit that handles the needed width and profilem maybe a ball end, so the marble rolls into the hole?

This method takes advantage of the way Shopbot code works, rather than using a 3D design package.

[shopbotgirl]

Ok great. Thank you so much for you help... everyone! I'm going to try this; if anyone else has more ideas, let me know.

Thank you all again!

Victoria

[jsfrost]

Use what I adapted from Morris, for the end line. Add similar code for the two segments at fixed depth.

[brucehiggins]

Another kind of convoluted option would be to draw the trough as if it were 1/8" wide at the ends flaring to 1/4" wide at the middle and round the ends w/ 1/8"diameter half circle. Then create the tool path specifying vcarve with a 60 degree bit and a diameter of 1/4" or greater. Then when you cut it use a 1/4" straight bit instead of a vbit. You would have to do the math to figure out the exact width and at the middle radius the angle where the angled lines meet.
Morris's suggestion is the easiest for sure.

[jsfrost]

Thanks for the idea Bruce.

Going a step further, we can do the math once for any sloping toolpath, defining a dummy 53.13 degree bit, and creating a vcarve toolpath with that bit. This way, with very little tolerance, the width of any closed vector shape at a point becomes the depth of the toolpath at that point. All corners must be rounded with diameter equal to depth at the corner.

With all the software I own,I have long wanted options to allow saveing a toolpath created with a dummy bit concatinated with other toolpaths using the actual cut bit. Now I want it more.

[brucehiggins]

53.13 - perfect Jim. I agree with you, it should be a warning msg when you try and save toolpaths w/ different bits to the same sbp file and you could override it.

[brucehiggins]

BTW, if I were a high school math teacher I would get with the shop teacher and purchase a shopbot. Some kids might pay more attention in class if they saw such practical applications of math.