True 3D vector tool paths?

[MDCochrane]

I've got a recurring project that would cut more efficiently with a true 3D tool path rather than using X or Y rasters -- think of a tool path that follows a vector in the shape of a letter "S" where the Z level starts at the material surface for the top of the S, dives down half an inch at the center and then returns to the surface for the bottom point of the S.

I have a couple Vectrics products but they don't support this type of vector-following tool paths.

Suggestions? Thanks!

Mike

[srwtlc]

If you don't have Aspire, take a look at the fluting toolpath in VCP. Try the various flute toolpath settings.

http://www.talkshopbot.com/forum/attachment.php?attachmentid=26403&stc=1

[scottp55]

Don't forget that with fluting toolpath, simply changing the profile/size/angle of the bit and the depth of pass(or ramp options) you can radically change the appearance of the finished look.
Have fun and play a little:)
Also good for lots of other stuff and shapes.
scott

[MDCochrane]

This is encouraging to see that VCarve can do this with the fluting tool; but now my challenge is to get the surface into VCP in vector format. The pattern is too complex to do directly in VCP and the CAD I'm using exports a dxf or stl file that VCP reads as an imported surface. I can't select, in VCP, the vectors along the X axis that make the pattern and assign them a fluting tool path. I suppose that problem would be the same in some other tool path generator, as well.

I'll have to look for some intermediate software translation that will give me the X axis vectors.

Here's what the surface looks like. It's a series of long "S"s undulating up and down. A straight X raster works, but a path that follows the S vectors might be much faster and better quality. (Picture is the bottom, left corner of a 4'x6' sign cut into Duna board - HDU).

26414

[Brady Watson]

Take a pic dead on. Pull it in, trace it out. I bet there is only ONE vector on that whole pattern that is unique.

Make each trough a CLOSED vector and make it bigger than it needs to be in length. Then v-carve with a ball.

I've done this countless times over the years with those patterns. I just did one a few weeks ago. It takes some patience and precise drawing, but you can do it. Then buy Aspire with the proceeds...

-B

[MDCochrane]

Brady! What a great idea! I would not have thought of using a Vcarve tool path, but I can see that it's doing just what my pattern is doing, that is, going deeper when the lines are wider apart and shallower when they are narrow.

Rather than trace a picture of the pattern, I selected the vectors that define the wave tops in the pattern and exported them from my CAD software as a ".dxf as 2D projection" -- a flat picture. I then defined each valley as a closed vector object, defined a virtual 2" ball cutter in VCP and ran the tool paths. The rendering looks perfect... and it's a 3 hour cut at a slow feed rate instead of a 10 hour cut at the highest feed rate I dared to run... smooth!... should require no sanding.

I ordered a 2" diameter round end mill from Freud. When it comes I'll run some test. I see from other manufactures that they don't want you to run a big bit like that any faster than 14K RPMs. I'll probably run it at 10K. (I tried smaller bits than the 2" ball; but the renderings looked bad.)

If this works, and I don't need to sand after cutting, I may have time to grow my finger prints back. There goes my side job as a bank robber...

Thanks for tip!

Mike

[Brady Watson]

Mike,
Just make sure your vectors are nice and clean ~ no abrupt direction changes, as few nodes as you can get away with and smooth the bezier nodes. Otherwise, this will telegraph into the pattern. The 3D toolpath preview should show any 'gouging'. You'll soon find that you will need to start with a larger model space and make your vectors longer (while remaining periodic) in order to account for the diameter of the tool.

Around 13-14 years ago, there was a company that was giving out samples of their textured wall panels at a trade show. It was really neat at the time because they were using a large tool and simple tool moves to create a lot of bang for the buck (in terms of low machining time). I followed up and went to their site. On one of their pages they explained that it took several months to come up with one of the patterns using software that they developed in house. I knew they were lying and figured there was a way to make the patterns in ArtCAM (there was no Aspire yet). One Friday night I put on a pot of coffee and started playing around, intent to duplicate the same kind of wavy pattern using a quasi-2D toolpath. It took me a few hours, but I cracked the code and was making panels from scratch.

These days...most have no idea how easy they have it with the amazing advances in software during the past 10 years. It was expensive, hard to learn and you were pretty much on your own. Now, Aspire has a wave pattern generator in it & some other specialized tools to make this sort of thing a breeze compared to the olden days. These tools probably won't be much help if you have to duplicate an exact existing pattern, but by using the tools it may help you to visualize the direction you need to go in while setting up the custom stuff.

I've used the Freud 2" ball for this work. It's pretty good, but run some test cuts first to make sure that the very tip where the two halves join is ground perfectly smooth. I've had a few that weren't and they went back...but most of the time they are dead on. I limit that bit to around 12-13k RPM in HDU and it is fine. You should be able to hammer along pretty quick. Tune up your tool before you cut and make sure your racks are greased properly. This will reduce 'noise' in your cuts.

Good luck - let us know how you make out.

-B

[MDCochrane]

Hey Brady,

When I started working on this design all I had was two photos from the artist's iPhone -- one straight on and one on edge... and the sign had to look EXACTLY like that. I never did see a physical sample. Took me a week to crack the code. All I had for cutting, at the time, was Cut3D, which, as you know, has no model editing whatsoever. So, I designed the texture in my BOAT design CAD, exported it into Cut3D and cut it as a raster along the X axis. That's how I got mentally locked into that thinking. Using one of the canned tool path strategies in VCP never occurred to me. So, thanks, again.

Here's another quick question before that bit arrives and I do some actual cutting. Do you know if VCP will auto limit the tool paths to the selected material size? I hope so! If not, I won't be able to cut a 4'x8' sheet without hitting the proxy switches. In order to get the right scale of the texture and cut it to the edges, I've got to overlap the material size by several waves on the model. (see the screen shot) Cut3D has a function to limit the tool paths to the model or material size. I can't find that function in VCP. Is it there?

26459

Mike

[Brady Watson]

What you want to do is, take a 48x96" and offset it to the outside 1/2 the diameter of your cutter. Then clip the vectors outside of this region...then rejoin them into closed vectors for v-carving. This may take some finesse.

A 9648 PRT will go somewhere in the neighborhood of 50x102" (or more), so you might just be able to eek by. Forget the limits. Air cut that bad boy to make sure you don't hit the HARD STOPS while cutting because HDU 'ain't cheap'...Feel free to move your mechanical stops ALL THE WAY to the very edges to maximize your machinable area.

After you rake in the cash...upgrade to Aspire...

-B