My definition of long isn’t likely the same as most of you, but I’m staring at an estimated time of 5 hours for this next project. A 5 hour block to sit and watch the machine is few and far between these days. Do you pause/resume during the job? Break it up in the GCODE? Run unattended? Remote monitoring?
Feeds & Speeds, DOC, and chip load are things I have not mastered so my confidence in my ability to run the machine is next to nothing. Most of this cut is a deep V-bit so a pocketing tool doesn’t really help in this case. I’m just curious what others are using to clear a lot of material or other ways to save some time.
Could you please post your DXF? It’s hard for me to imagine such a long time just with V-bit-carving. I would like to recreate the toolpath so I could tell you if the 5 hours are realistic.
I do a lot of long jobs (longest was 12h so far) in a cold garage and have tried to deal with this issue in a number of ways:
Make my MPCNC go as fast as I can, with lots of mods. (see my other posts)
Move the mesh Wifi in our house so it reaches out to the garage and put an extra surplus monitor on the CNC laptop so I can get work done or browse the web while the machine is making sawdust for hours on end.
Install a videocamera (like a baby monitor) with sound to monitor the CNC on my phone if I have to run to the loo.
Bring snacks and water out to the garage.
Install a parking heater and insulate the garage so it is not so damn cold.
Get a respirator that is comfortable to wear all day (Sundstrom).
Set the machine’s rapid rate (for when it is moving through air) and acceleration as fast as they can safely go. Any time it is running and not making chips is wasted time, IMHO.
And as was alluded to by Philipp, I work hard to optimize my toolpaths.
You can get wildly different job times by just making one small change. I use VcarvePro which has a very good estimate of how long a toolpath will take.
For instance, I only use a V-bit to do the edges of a Vcarving job, and use the biggest flat endmill that can pocket all around the Vcarved stuff.
I use 50-80% stepover, and as deep a cut per pass as the machine and bit can handle.
It is worth breaking a few cheap bits on a similar type of scrap wood to find out what your machine’s limits are. I learned this lesson from my Uncle Dick who races rally cars: “If you never skid the wheels, you will never know how fast you can take a turn.”
Not sure why the SVG isn’t displaying correctly on here. It is a 3/4 inch piece of acrylic that I’m trying to carve. I’m using a 30 degree V-bit for the M and then a 15 degree V-bit for the Meszynski. The M will be about 1/4 inch down and the last name will be about 1/2 inch down. I want the front to be the flat side and I’ll have LEDs around the edges to light it.
Looks to me like you’re trying to use the v-bit for doing the flat sections too? That’s what’s taking so long. Use a flat end mill to do a first pass at creating all the flat parts. Then switch to the V-bit to make all the chamfers.
it’s been a while since I’ve done this, so I don’t recall how estlcam does that, but I know it has the ability to do it.
It can define the pocket tool separately. You can use a flat endmill for the pocket tool and it will do the roofing pass separately.
It probably won’t work in acrylic, but you can sometimes do those layering jobs as separate thin sheets, and the pockets become holes, which are way faster. The time it takes is proportional to the lengths of paths it has to take. So pockets are exponentially longer.
How big the the final logo going to be?
To your original question though, Steve has a lot of good suggestions. I have also split the gcode up into multiple jobs. If the machine stays powered, it will not lose its coordinates. I would be fine leaving it on, as long as it couldn’t turn on the router while I sleep.
Okay, I played around with it a bit. First of all I changed the speed for the 1/8 endmill to be faster and added trochoidal milling, so it won’t gum up even without cooling. I also set the Z-Depth to 3mm of the 30° and 15°. That makes it a lot faster already:
Secondly, you set the depth limit to “Automatic”. It then basically goes as deep as the endmill allows. With your former 2mm passes, it goes deep and takes a lot of time. If you limit it to a depth of 3mm this is what it comes up with:
Trochoidal milling is something I’m going to have to look at and explore.
The depth limit at automatic was done intentionally. That meant the 30 degree bit would go down about 1/4 inch and the 15 degree would be about 1/2 inch. Since the front of this is the uncut side, I wanted it to show more depth for the cut. That would hopefully light up better when I have LEDs surrounding it.
The bits I bought for that seemed to have trouble at the at least in wood were having issues going faster than what I had them set to. Admittedly, I have already bit the bullet and did this carve at the extended time. I figured the amount of time I spend tweaking and trying things out would be much longer than the time I could actually save for this particular project. But I need to do some more personal projects to learn more of these things. That’s why I originally phrased the question about what to do about longer cut times and what things I could do to help with that. All of the suggestions so far are greatly appreciated and I’m open to receiving more ideas and support.
Definitely could have done better, but it turned out well enough. The scratches and stuff will need to be sanded and polished out, but that’s a problem for the other guy working on this project.
Yep, it turned out. It got me where I needed to be, but I’m going to try some of these suggestions on the same design with scrap wood. I want to see if I can achieve the same results, but in significantly less time. All in all, that carve was over 4 hours with the tool changes.
I felt a little guilty because I ran it before I used any suggestions here. I didn’t want it to seem ungrateful, but it was getting to be a time sensitive project that I just needed done and out of sight. But the suggestions here will definitely help when I have longer projects.
