Multiple moves doing nothing...

[letterman7]

Hi gang,
I finally got time today to play with PhotoCarve. I routed into clear acrylic, so I really can't show anything - it'd look like a piece of glass! Anyway, the file executed almost fine, with a couple weird little things. I'm running an older PRT ShopBot with the VC software. First problem: the Z axis is hanging above the material. I've zero'd to the table, and have entered all the data correctly for the material thickness, etc. I used an engraving bit in this instance, but it also happens with V-bits - once the program starts running, the bit is anywhere from 1/8 to 1/4" above the surface of the material just going through the motions. If I reset the program and scale the Z axis in SB to 75-85% of the working height, the tool goes where it's supposed to. I must be missing something simple. I read through the thread concerning losing the Z axis upwards, but this is different - it's simply not setting the tool where it's supposed to be. The other issue has only shown itself with PhotoCarve - standard V-carving is fine. As the photo is etched in the material, the tool will make two passes for every one pass it actually cuts (across the image). It almost seems like it's a cleaning pass, but the Z doesn't change. Is that something perculiar to PhotoCarve? I hate to think I've got to edit all the part files I want to cut just to rid myself of those extra steps.
Thoughts?

Rick

[Burchtree]

Hi Rick
Two things come to mind. Are you zeroing your tool where you have it set in PVC and look and see what the pass depth is for the tool you are using.
Dan

[letterman7]

Hi Dan,
I'm not sure what you mean by zero-ing where it's set in PVC. I usually zero at one spot on my table, right at the x/y endpoints. It just makes it easier. Normal 2D cuts go fine, I can get the cutter to just skim the spoilboard when I'm cutting parts. What I am doing is importing the PC file into VCPro to optimize my material and be able to add elements around the image. Maybe that's where the issue is coming in. Ah....but I just saw something as I'm looking at the file while I'm typing this: the Z/Zero selector (top/bottom) I have it selected for the bottom, or table. To the right is the thickness (Z)....I have the thickness of the material in that box. Am I that obtuse that if I'm Z-zeroing for the table that the box should also be 0, rather than .5 for the material? If that is the case, then if I'm Z-zeroing to the material top, then that box should have the material thickness in it? That would probably have been obvious for most of the users if I'm thinking correctly...but that just never occured to me and would explain the 2.5D issues thus far.

R

[Burchtree]

Hi Rick
I should have said Z zero. When you are in PVC you have the option of top of the material or machine bed for Z zero. The thickness of the material should be set at what ever the thickness is.
If you are importing a PVC into VCP it needs to be set up the same way. I use the top of the material as my Z zero 99% of the time and all of my PVC’s go into VCP before machining. I have a 5 year old ShopBot PRT. I would try the top of the material as your Z zero and when you call up your v bit to use in PVC check the pass depth it should to greater than the cut depth if you want to cut in a single pass.
Hope this helps
Dan

[letterman7]

Ah! Ok...so it doesn't matter to the machine whether it's Z/0 at the table or the top of the material, so long as there is a numeric digit in the thickness checkbox. It's been a while since I've worked on a CNC machine - at least ten years...and I bought the SB for a song! Anyway, good call on the pass depth. I'm going to try some Corian today..I'll keep you posted!

Rick

[calgrdnr]

and I bought the SB for a song!

Which Song ? I sure would like a SB

[letterman7]

I wasn't really looking at SB's...I had my heart set on a more open architecture routing system. I just couldn't afford what I was looking at. At the same time, I found an ad on one of the sign forums of a shop going out of business four hours away...and the 'Bot was going too. Bottom line - price was right, so I grabbed it. It does take some getting used to, but so far, so good.
Now, back to topic: routed a litho today and learned some valuable stuff: use the lightest color solid surface you can find. I used Corian Sand, 1/2" thick and routed 1/4" into the surface. The photo below was taken with a 100 watt floodlight behind it.

Needless to say, even the most basic box won't illuminate this, but it was a good learning lesson. I may try it again with a total depth of .45" just to see what happens. I used an engraving bit on this one; I may try a V bit on the next. Dan, your suggestion of setting the pass depth greater than the cut depth worked perfectly. It (literally) cut the routing time in half - down to 2.5 hours on an image that's 9.5" x 8" overall.

Now...what other trouble can I get into since I still have the Corian on the table....?

[Burchtree]

Hi Rick
Nice work. If you want to practice for low cost you can use cheap white plastic cutting boards. 1/8 inch round nose bits run fast and will give fairly good detail if the picture is good sized. ( 8x8 inch of a persons head for example )
Dan

[CRFultz]

Nice work on the litho Rick. now your hooked like the rest of us.

[calgrdnr]

Hook, line and sinker, you are now a litho addict

Very nice Rick.

please keep sharing your future work


thanks Kent

[letterman7]

Thanks, guys! Yep, it's addicting for sure. I'll be trying the same image today with a modified file...going for that 'cameo' look. We'll see what happens!

[letterman7]

Ok, round two (how come we can't edit posts to save space?). Here's the same photo, different style. The first round I had vignetted the background from white in the center to black; the second I did the other 'way round. In essence, the first piece is domed in the middle except for the dog, the second it's dished (lightly). I also milled the Corian down to .25", then in milling the photo, set the total depth to .20, so the thin areas are very thin. Sorry for the little bit of overexposure... I'm still not sure about this sand color, though. I think the next couple I'm going to try the basic white, and experiment with inlays on the sand piece.
So...I'm now a PC convert! Interesting stuff, for sure....!