[Gallchobhair]

I am looking for a Tutorial on how to slice a large 3D model I mean a model that would be to tall to cut in a single go. I would like to be able to cut it in slices and assemble after. I thought I saw one at the afterdark site but could not find it. How the boat hull Trotline LoL.:drowning:

Thank You
Don

[jrmach]

I think Mr. Burr might of made one.Check his You Tube

MrBobhuh - YouTube


Doing a search of the Forum reveals this http://www.cnczone.com/forums/bobcad...thick%20model=

[mmoe]

Is it a solid model or a mesh model (STL)? How you do it depends a bit on what you are starting with.

[Gallchobhair]

Mmoe I am using stl for now. If I could get Meshlad to skin it that would be nice. Can Bobcad skin an stl ? I am stuck with stl or obj as I have no cad
Program other then Bobcad. I use Bobart as I do not make parts. So far I have been able to do most of the things that I see on the Vectric site at a
Fraction of the price. If anyone knows anything about Meshlab help. I do know how to make height maps. Have not done to much with it but it is a one
Button thing and a couple of sliders.

More the you asked. Lol
Don

[BurrMan]

Set the model in the workspace and just use the top and bottom of job settings to limit the depth. Translate the model up the amount of each slice to keep the gcode at "zero" or wherever. You could probably achieve the same "translate the model" part using machine setups or by manipulating the origin.

[Trotline]

Burr's suggestion is the way I'd have approached the problem, as well. Before I tried it, though, there are some things to consider. Are you looking at doing a very large version of one of the heraldic crests, or something different? Slicing a complex model like that could pretty easily leave you cutting out a virtual lacework of a part. Holding it to the table would be a nightmare, and getting it off in one piece might be even worse if you're talking about something fragile like MDF.

Is the limitation the gantry clearance, or the length of the endmill? Personally, I'd much rather spend $20-30 on an extended length endmill than fight with sections, if it's simply a matter of tool reach. Sectionalizing a part is simple in concept, but the execution is likely to be a might ticklish.

Luke

[Gallchobhair]

Trotline: No not the heraldry things but a large model of the Disney Nautilus. My travel on the Z-axis is about 6.5". It would be the length of the router bit. I may look into longer bits when I get ready.
I would also want to do 2 sided cutting. I would also like it to be cut in foam. I have not tried doing anything in foam yet. I may need some input and info on cutting foam. The cncrouterparts machine
X travel 49.75 inches
Y (gantry) travel 26.75 inches
Z (vertical) travel 6.5 inches (minus spoil board thickness) so I have about 4 or 4.5 " to use.

Thank You
Don

[Trotline]

Hmm, I was setting up a part to demonstrate the method of translating a model through a given stock, using top/bottom of part to control the toolpath, as I've done with earlier versions of BobCAD, and I've hit a snag. It seems as though the change to DMS has affected the way this gets done.

Anyone know how to work around this? In the included file, the first (small) section is already toolpathed, and the model translated up 2". The same feature is copied, and the model selected as the geometry. I'd set the "Top of Feature" at 2", but the system won't generate a toolpath with that setting. Editing it to 2.4" generates a toolpath, but it rises up out of the stock, which kinda defeats the purpose.

Luke

[mmoe]

Luke seems to be onto a good solution, so I'd continue with what he's doing unless you run into problems.

There are ways to slice a mesh, but none that I would say are user friendly or inexpensive. You could probably use "Cloud Compare", which is free to download and use. The main issue is getting the slices to end up exactly on the same plane. Generally, when I slice a mesh in Cloud Compare, I am doing so in a way that creates an overlap so that I can seam the parts back together with some alignment later in Meshlab. Not to say it's impossible, but I don't think I could give accurate instructions to do a perfect slice of the object, though I seem to recall that it may be able to be set to split a mesh; where it doesn't toss the sliced off data, but instead keeps it as another mesh. If you are able to split it, you may (probably) still have to fill in the holes where it was cut.

For future reference, a solid is much easier to do this sort of machining on. You can use a solid block representing your stock along with an boolean intersection operation to create a slice of the part. I have a feeling that what Luke is demonstrating is similar in practice, but I do think that a solid will always offer more machining options than an STL. If you can only get an STL, there isn't much around it, but if you can get a solid instead, that would be preferable.

There is another option that I'll offer if you can't get what you need done. Since I do a lot of work with different kinds of files, I use some additional CAM products to supplement Bobcad for specific tasks such as this. I use Bobcad for at least 90% (probably way more) of what I do, but sometimes is just faster to use a specialized product for those rare cases where it's not something Bobcad does well. I do have a CAM product that has a built in STL slicing operation that I'd be willing to run your part through. It will spit out new STL files that represent each layer of the model, which you could then machine easily. Ideally, I'd like to see the solution in Bobcad play itself out first, but if that doesn't happen you can let me know and I'll split the file for you.

[BurrMan]

Hmm, I was setting up a part to demonstrate the method of translating a model through a given stock, using top/bottom of part to control the toolpath, as I've done with earlier versions of BobCAD, and I've hit a snag. It seems as though the change to DMS has affected the way this gets done.

Anyone know how to work around this? In the included file, the first (small) section is already toolpathed, and the model translated up 2". The same feature is copied, and the model selected as the geometry. I'd set the "Top of Feature" at 2", but the system won't generate a toolpath with that setting. Editing it to 2.4" generates a toolpath, but it rises up out of the stock, which kinda defeats the purpose.

Luke

Yeah, that didn't work for me either. It will take some thought....

[Gallchobhair]

mmoe thank you for the offer to slice the model. I will keep it in mind. I was looking for a so;ution not just for this model but for future use. I have looked at Cut3D and Meshcam both handle
cutting large models very easily. I thought maybe Bob could do it.I am working on something that may work and then again may not . Lol. I have a new thing I would like to see if anyone
has a quick work around. I will start a new post. New problem new post.

Thank You
Don

[Trotline]

I came back to this problem again today. I've done sectioned work in the past, and I thought I'd just translated the model up through the stock area, using top/bottom of part to control the toolpath. So, I tried it in V25, just as a sanity check. Same issue there as I saw in V26, so it's nothing new or related to DMS. Apparently, I just sectioned the model as needed, last time.

Don, this is an easy thing to do with a "regular" solid, in BobCAD, but you'll need an external slicing tool, such as mmoe discussed, to handle slicing a .stl mesh. Frankly, you'd be doing yourself a favor by spending time with the solid modeling tools in BobCAD. They're not the best, but they give you lots of options, as in this case, that a mesh just won't. When you rely on "found" files, you're locked into whatever baggage they come with. BobCAD, like a lot of other packages, is limited in its ability to manipulate meshes. Some things, it handles well. Others, not so much.

Luke

[mmoe]

I came back to this problem again today. I've done sectioned work in the past, and I thought I'd just translated the model up through the stock area, using top/bottom of part to control the toolpath. So, I tried it in V25, just as a sanity check. Same issue there as I saw in V26, so it's nothing new or related to DMS. Apparently, I just sectioned the model as needed, last time.

Don, this is an easy thing to do with a "regular" solid, in BobCAD, but you'll need an external slicing tool, such as mmoe discussed, to handle slicing a .stl mesh. Frankly, you'd be doing yourself a favor by spending time with the solid modeling tools in BobCAD. They're not the best, but they give you lots of options, as in this case, that a mesh just won't. When you rely on "found" files, you're locked into whatever baggage they come with. BobCAD, like a lot of other packages, is limited in its ability to manipulate meshes. Some things, it handles well. Others, not so much.

Luke

Another possibility might be that you could just set your max and minimum machining limits in the toolpath, with the minimum height representing the same as the bottom of the stock for that slice (probably by changing the origin height or by translating the part), then create a plane at the height of the maximum limit which you could crate a toolpath on as a separate operation. This would allow you to machine the areas that need machined down to where the last part left off, then plane off the material at the top to meet up with the next slice. It might be a bit more round about, but I think it would be possible to get it done. You'd just be cutting a lot of air, but with a large enough bit or a smaller project that wouldn't be too much of an issue.

Otherwise, I haven't tried it and can't say what you're running into for the max/min limits issue.

[mcphill]

There is another option that I'll offer if you can't get what you need done. Since I do a lot of work with different kinds of files, I use some additional CAM products to supplement Bobcad for specific tasks such as this. I use Bobcad for at least 90% (probably way more) of what I do, but sometimes is just faster to use a specialized product for those rare cases where it's not something Bobcad does well. I do have a CAM product that has a built in STL slicing operation that I'd be willing to run your part through. It will spit out new STL files that represent each layer of the model, which you could then machine easily. Ideally, I'd like to see the solution in Bobcad play itself out first, but if that doesn't happen you can let me know and I'll split the file for you.

I searched for this "other program" yesterday and found Netfabb: netfabb Software - Software for 3D Printing - 3D Software for STL files - fixing, repair, editing, merge STL data for Rapid Manufacturing - STL Viewers and STL repair

What a piece of software of the price!!! I bought it right away, and it does WONDERS for working with and cleaning up files. I have always wanted Magics, but can't afford that. Netfabb is easily affordable and does a lot of the things I wanted Magics for. Thanks! (is this the "mystery software" you were referring to, and why didn't you post the software name?)

[mmoe]

I searched for this "other program" yesterday and found Netfabb: netfabb Software - Software for 3D Printing - 3D Software for STL files - fixing, repair, editing, merge STL data for Rapid Manufacturing - STL Viewers and STL repair

What a piece of software of the price!!! I bought it right away, and it does WONDERS for working with and cleaning up files. I have always wanted Magics, but can't afford that. Netfabb is easily affordable and does a lot of the things I wanted Magics for. Thanks! (is this the "mystery software" you were referring to, and why didn't you post the software name?)

I'm not familiar with that one, but if it works, it works! What is their pricing like? I use Meshcam for STLs, which I didn't post mostly because I'd like to see the solution done in Bobcad. From a professional perspective, $250 for Meshcam is not a huge investment and it handles STLs very well, as it should since it is written for meshes specifically and can't do anything with solids. For the hobbyist, I would imagine that spending another $250 might be more than a person is willing to do. In Meshcam, you can create the STL slices as new STL files, but since the CAM is already there, I usually just opt to finish the job inside Meshcam. For anything other than larger STLs, I prefer to use Bobcad, but I find Meshcam useful once every month or two.

[mcphill]

Netfabb has a free version that will fix errors in STL's, certainly worth "free" just for that. The Personal license is about $250 and lets you do a LOT more (I think it give full "Professional" functionality but for a hobbiest price and non-commercial use). You have to get a quote for the Professional version, which I did not do, so no idea on cost for that.

"ALL" the program does is work with mesh files, though. No CAM or anything else. I bet Meshlab can do a lot of what it does, but I find the GUI and interaction with Meshlab to be difficult to learn and there are no great "hold my hand and walk me through it" tutorials. I have already done more "constructive" work in Netfabb in 1 day than I have in Meshlab in 2 years. I mostly use Meshlab as a quick viewer, and certainly sent a link to it for anyone that doesn't have an STL viewer.

[Gallchobhair]

I am going to answer a couple of questions I have been asked in this thread. Why I don't model in Bobcad. I know nothing about Cad. For me to try and model the Nautilus well ???? LoL..I have been getting stl files but I can also get Cad type files for some of the things I want to do. At 73 I could venture down the road trying to learn Cad programs. I also can just get what I need how I can and make a lot of toothpicks.Some models are free and some I buy. Can't get everything for free. This group has been a BIG help to me.I would still be on page one if you guys did not offer the help you do.I can see some of the things I ask about set you on a path you may not have traveled if I did not ask. So until I am asked to be quiet and go away I will keep asking.

Thank You ALL for your help
Don

Got a whale of a tale to tell you Lad,

[Trotline]

I'm digging up old threads again. Not long after this thread tapered off, Al Depoalo posted a video where he showed using solid models as stock, altering and saving them from within the Simulation. I'd seen some posts of this function before, but after watching his video, it occurred to me that it might apply to this question. So I tried it, and it works. Here's a video showing the workflow for using this to section off an .stl model into layers, suitable for cutting and re-assembling into a part larger than the working area of a machine.

Sorry for the laggy quality of the video. My machine can run BobCAD with fairly large .stl meshes, but when I add the video capture software to the load, I start wishing I could afford a real workstation.



Luke

[Gallchobhair]

Trotlines is on a roll. Living in the past Trotline . LOL

Don

[Trotline]

lol, to paraphrase CeeLo Green, I may not be a Ferarri, but that don't mean I won't get you there.

Luke