Cutting Depth / Clean up pass

[prosigns]

clean up pass

I'm hoping someone can help me with this. I would like to make .20 flute cuts in oak and then do about a .01 clean up cut. If I set the depth at .21 with a .20 per pass depth of cut, it cuts 2 passes @ .105 each pass. Is there a way to set it up in one operation so it makes the full .20 pass and then follows with a .01 clean up pass? Right now I'm setting it up as 2 seperate operations. I'm Hoping there's an easier way.
thanks

[billp]

Prosigns,
What sofware are you using? In some software you can "lie" to the machine and tell it that your bit will not cut as deeply as it really CAN. This way the program will compensate and automatically know to make a second pass. So in your example you'd tell the machine your bit only had a depth of cut of .20. Then it would know enough to make the second pass at .01
I think you can do this in Part Wizard as well as a number of other programs...

[artisan]

As Bill says,..the solution is very dependant on the software. In most toolpath software, the surest way is to write 2 separate toolpaths and then group them as one....D

[prosigns]

I'm using Shopbot's control software v. 2.39exe.
I have always had this problem (not really a serious problem). If I want to cut 1'' deep and I cut @ .25'' per pass it will make 4 passes and it's done. If I want to cut 1.01" deep @ .25'' per pass it will automatically make 5 passes but it always divides the passes into equal depth cuts rather than making the last pass .01"

[prosigns]

and part wizard version 1.2

[billp]

Prosigns,
Darrell has the answer..If you use PartWizard you can make two separate toolpaths, BUT when you go to save them, you can place them BOTH in the right hand save box, and save the two of them with ONE name. This way the machine will call ONE file, but do it in TWO passes...So you'd do one toolpath at .20, and the second at .01, call the first one "pass1", the second one "pass2", and then save them combined as "full cut"....

[prosigns]

Thanks. Bill
I had another problem crop up. A little more serious. I posted it under Choppy machine tool path. I've never seen this happen before. Any ideas?
gary

[richards]

If all else fails, modify the SBP file. I'd recommend generating one SBP file and then copying the section that cuts the flutes. The first time through adjust the Z cut to -0.20 (assuming you reference from the top of the stock), i.e. MZ,-0.20. The next time through, change the Z height to -0.21.

Right now I'm building a test file to do something similar. First I generated a SBP file from PartWizard, specifying a 1/2-inch cutter. Since PartWizard would not allow me to save a file with two different tools, I next generated another SPB file, specifying a 3/8 inch cutter. Finally, after opening two sessions of MS WordPad, I combined parts of both files, with the 1/2-inch cut coming before the 3/8 inch cut. When I actually cut the plywood, I'll use the same 3/8-inch cutter for both cuts; however, the first pass will leave 1/16-inch of material for the cutter to remove, while the second pass will just be a cleanup pass.

(Granted, if I had the proper tooling and a spindle instead of a PC router head, I could probably get the desired result in one pass; however, a local Shopbot owner has been kind enough to offer to rent some time on his machine to test the water before buying my own machine. Right now I'm just very pleased that I can finally try things out to see if theory matches anticipation. Preliminary tests have left me amazed.)

Mike

[thecheneys@juno.com]

Mike,
It seems you've gone to a lot of trouble to accomplish a task which PartWizard will already do. Creating two cutting paths along the same part is accomplished by creating the first toolpath with the Pseudo 1/2 inch bit and saving it then select the tool tab and un-check the 2D view of the first toolpath you created with your pseudo 1/2inch bit, then go back to the assistant tab and select the same part and create another toolpath with your 3/8 inch bit. I would probably name them something really original like "cut 1" and "cut 2" When you save to disk as a SPB file you can select which cutting paths and the order you want to cut them in. Creating Pseudo tools is a great way to lie (excuse me - fib )to the software. I have created a Pseudo Tool File in the tool library for just such bits. They don't even have to be any standard size. For instance instead of using a pseudo 1/2 inch cutter for your first pass you could have made it only a couple of thousandths larger than the final 3/8 inch cutter. I hope this helps.
Lee

[richards]

Lee,

Thanks for the suggestion. Saving each tool path to its own file would work great.

However, what I'm trying to do is to create one file for each object. For instance, the part I'm building a file for now has two drill holes, one pocket and two perimeter paths. In addition, the file prompts the user for the number of parts to cut from the sheet of plywood. By having a single file, the operator can walk away from the machine as soon as the routine starts to do other things. If I were to use multiple files, at least on this particular piece, I would have to load four files to make the same number of parts.

Mike

[mrdovey]

Mike...

What would prevent you from writing one additional (master) file to call all of the others in sequence, with all dialog taking place in the first:

FP FILE1.SBP ' This file has operator dialog
FP FILE2.SBP
FP FILE3.SBP
FP FILE4.SBP
END

Now you can run all four files and not have to start each one manually.

Morris

[thecheneys@juno.com]

Mike,
Perhaps I was not very clear in my explanation. But I was trying to say that PartWizard does allow you to save mutiple cutting paths into one .Sbp output file and that some of those paths may be repeated over the same vector with different tool characteristics.
Lee

[robtown]

Hmmmm...
I get a message saying " selected post processor does not support multiple tools" when I try to create a cutting file with more than one tool defined.

[Brady Watson]

Rob,
You can't group 2 or more toolpaths into a single SBP if you are using more than one size bit. In other words, it is telling you that you can't run a 1/2" bit and then do a pass with a 1/4" bit in the SAME SBP because it doesn't support a tool changer.

In order to group 2 or more toolpaths into a single file, you need to run the same diameter bit on all of them. If you are changing bit sizes, then just make 2 separate toolpaths and change bits in between.

-Brady

[robtown]

No, I get this message when I try to use two tools of the same dia. but with different settings (from the same group even).

[lee]

Mike Rob, Brady,
My appologies to all, you are absolutely right!
I don't know what I was thinking. Part Wizzard does allow you to create different cutting paths with different tools along the same line but you cannot save them to 1 .sbp file. Only 1 tool is allowed per .sbp file.

Mike,
An alternative way to cut out your parts and then do a cleanup pass would be to offset your cutout path a couple of thousandths and create a roughcut path along that new line, then create a cleanup path along the original part, both using the same bit.
Lee