Confused V carve corners not sharp?

[jhicks]

We havent used this package much but are starting to get into it with the new 4.0 upgrade. We are trying to figure out why a sharp inside and outside corner being v carved with a 120 deg v doesn't end up square/sharp?
The outside corner or what would be the centerline of the bit corners with a radius and the inside corner tapers inward as it approaches the inside corner. Following the centerline of course so that corner we are trying to have sharp on the top of the material and outside profile is not even close to visually acceptable as corner cut are radiused???.
It seems nice in preview but not in practice?
Are there some corner tolerance settings or something?
I would post a photo but dont have my usb cable handy now.
Any ideas on the cause of this?
Thanks

[richards]

Jerry,
How much of an error are you getting? What I mean is does it look like the corner would be sharp if you used a 118 deg v cutter, or a 122 deg cutter? If that is the case, can you specify a 118 or 122 deg cutter?

(When I wrote the tool pathing part of the the doors program (Bruce Clark's Freedoors program), I had to make allowances for cutters that were not exactly 90 degrees. To do that I allowed the user to specify something other than 90 degrees for the cutter. The cutter that I normally use gives me a sharp corner when I enter 89 degrees instead of 90 degrees in the doors program.)

[knight_toolworks]

check the tool settings make sure everything is right there. and check for flat on the material your cutting.

[srwtlc]

Jerry,

If this is a "Profile" toolpath with a v-bit, there are some check boxes for "Sharp" inside/outside corners on the "Corners" tab.

If v-carving though, for instance a square corner, the inside corner will/should be square at the surface, but the tool will draw a radius at the bottom and round the inside face or wall. That's one thing that has always bothered me with VCP, but I guess it's a necessary evil due to the fact that the tool needs to go deeper in order to follow the intended shape.

Otherwise, check the tool geometry and material thickness variance as Mike and Steve stated.



3862

[Brady Watson]

Jerry,
See attached. I believe this is what you want. Note the 'Inside' strategy & corner options.

-B


3863


Jerry.zip (http://www.talkshopbot.com/forum/messages/26/Jerry-22990.zip) (2.6 k)

[srwtlc]

Yup, but "Inside" is the only choice that will do it that way. When using a v-bit, it would be nice to be able to choose any way.

Not all shapes will work though.


3864

[Brady Watson]

Scott,
Nice work on the testing...I hammered on it a bit & it seems that if you are really bent on cutting out that arrow shape for a customer (I'm saying if you had to and you're about to bang head into wall), it can be done...but it involves a little node editing to get the desired result. See attached for details.

-B


3865


Jerry2.zip (http://www.talkshopbot.com/forum/messages/26/Jerry2-23001.zip) (2.6 k)

[srwtlc]

Good one Brady!

Not that I need to make an arrow as such, but with VCP, where there's a will there always seems to be a way to get to the desired end result. Otherwise there's the chisel.

[jhicks]

Thanks guys, I understand your feedback Mike and did try fooling the bit to 121 and 119 but neither change the results to a sharp corner.
I also see square commands and used those too as Brady & Scott suggest.
Here is a photo to better explain the results and confusion.
Notice the 90 degree top of the number 1 seems square but the corners on the inside, outside, and centerline curve inward or outward. Art shows non sharp centerline tiool path as well.
I would post the tool path and 3 d view if I could figure out how to save it in a proper file type or size so any tips on that are also appreciated.
Thanks


3866

[srwtlc]

Jerry,

If you would like, I can take a look at the file (e-mail in the profile) or another good thing to do is to send it right to Tony or Brian at Vectric with an explaination of the problem and all toolpaths saved in the file. They're very good about getting back to users.

If you don't want to expose the whole file, just take out the offending portion.

I created a corner like yours and in the preview and as expected, the inside corners are rounded. The surface edge is straight and true though.


3867

When in 3D view, place a check in the toolpath you want shown in preview and then choose "Save Preview Image" in the view menu or the button on the preview pane. You will most likely need to open the .jpg in a image editing program (I use CorelPhoto Paint) and crop it and resize until you get an acceptable file size for the forum.

Is the artwork straight and true? Check it in node edit and look to see it the short lines at the corners are possibly small curves.

Has the v-bit that you have been resharpend at some time? I had one that I thought I'd let my sharpening guru sharpen it and no amount of angle setting adjustment would remedy the bad corners that it was cutting.

[srwtlc]

I'm not sure why they round those corners. I have drawn my own toolpath for something like the above in VectorXT and have had good luck with the results.

[jhicks]

Thanks guys, sorry I didn't post earlier but its been a challenging week. Regardless we appreciate the tips and used the profiling rather than V carve between vectors as suggested with sharp corners and got it done.
Have to look into vector editing to get inside and outside understood and study why it doesn't accomplish it on its own. Agree with Scott but sure there must be some reason tony didn't build this functionality in.
Anyway, thanks and we'll post some photos when we have them and some spare time.