Archive for the ‘Tools’ Category

3D Printing software

Friday, February 14th, 2014

I’m looking for a good solution for 3d printing, but have run into show-stopping problems in everything I’ve tried (I need to combine a mesh with a geometric object). I’ve used AutoDesk Inventor Pro, Sketchup Pro with extra plugins, MeshLab, NetFabb, OpenSCAD, TinkerCAD,  and some others. Blender looks like it might be capable, but it’s an enormous effort to get into it far enough to tell. It’s extremely modal, and tools disappear when I need them, but reappear when I am doing something else. Maya has also been recommended to me, but that too has a difficult learning curve.

The fundamental problem is that if you do a Boolean operation on two 3D mesh solids, the result is no longer a valid 3D mesh solid. The repair tools can work on the result and be made happy, but Sketchup still refuses to consider the result a solid so won’t allow further steps to be done.
I’ve spent days and days trying to get past this barrier, trying tools and trying hand repairs, always stopped by one insurmountable (by me) problem or another.
There are an enormous number of combinations to learn and experiment with, so this could take a very long time (or I could give up until the software matures).
If anyone can recommend a path that can combine geometry with (valid) mesh solids in a way that can be made to result in a valid mesh solid (so that I can print it), I’d sure appreciate the advice…

More history and ranting

My current struggle started with a Sketchup Pro model done by someone else, modeling a complicated aluminum extrusion. I made a mating part to plug into the end of the extrusion, and printed that, only to discover that the real extrusion is slightly different from the drawing.

I couldn’t make Sketchup do the needed reshapes without it screwing up (I know there must be a way, and now I know that Layers mean something totally un-layer-like in Sketchup, and you are supposed to use nested Groups to get layer-like effects.)

Somehow in the process, Sketchup stopped thinking I had a legitimate solid, so I exported it to STL and used NetFabb’s repair tools on it, which wrap the object nicely (I thought). I eventually got an object that prints and fits properly in the real extrusion, but now I need to add a rounded bulge to it–the project is to make safety bumpers for the extremely sharp extrusions, to save my clothing and my skin. The extrusions are EurekaZone track-saw related products, and I’m always running into them as I walk around my work table or duck under to get tools off the shelves below.

Anyway, I can’t get the Sketchup part that prints and fits to be considered by Sketchup as a valid solid (indicated by Sketchup displaying a volume measurement for it), and until that happens I can’t further modify it in Sketchup.

There are plugins one can add to Sketchup (Solid Inspector, Solid Solver, etc) that analyze a mesh looking for problems and helping you fix them, but I can make them happy (with a lot of effort) and yet Sketchup itself won’t accept the result.

I’ve used various tools to examine the form, and by removing a skin I can look inside, and see little starbursts of spurious vertices that have somehow been created in the process of manipulating the STL mesh. The triangle count went from around 10000 to 1500000, so it’s not easy to fix manually, though I’ve tried. They are often connected to external faces, so if I select a cluster of vertices and delete them, some of the external faces also disappear. Of course, I can replace those manually too.

One approach that appeals would be to delete all but the external surface vertices, and then manually add the real edges and faces back, but I don’t yet know how to do that. I no longer know the true dimensions of all the features, because they were developed in a process of repeated reshapings, but some tools are able to show vertex coordinates, so I should be able to find them (but it’s very tedious–I likely need a few hundred, a lot to write down if it comes to that).

MeshLab looks capable, but you need to know the Mesh business in order to know what to tell it to do. There must be suitable books somewhere, but so far I haven’t found an easy entree that makes MeshLab approachable. I can’t face just trying everything to see what it does.

Blender looks promising, and I started using it, but the interface is difficult. In an experiment, I managed to select two vertices and wanted to put an edge between them, but could not find a tool that makes edges! Obviously there exists such a tool, and I’m sure I saw it once, but now I can’t find it. If your hands brush against the keyboard, every key you touch does something, often apparently irreversable (you can undo the actions but not the mode changes I think), and leaves you in a mode you’ve never seen before. (This must be an exaggeration. Surely.)

I’ve been working my way through a Blender book I bought, but it is aimed at amazing goals like making proper textures, base meshes, etc in preparation for making movies, so it’s going way too deep in directions that I’m not currently interested in, but I need to have some acquaintance with those topics if I’m to recognize some new context I suddenly get switched to so I can figure out how to get back.

Of course, this is not an important project. I could solve my problem by gluing bits of carpet to the part I can print now. But I want to know how to do such things, and it surely must be possible! Somehow the current software seems simultaneously extremely sophisticated and extremely primitive…

I spent 5 hours yesterday printing my first DualStrusion project, a blue Valentine heart with some white text embedded (but slightly raised). The print finished when the heart surface was reached, leaving the white text (mostly hollow) without its top layer. Sheesh. Not my fault…
I’m tempted to get into the GCode level, which I do regularly with laser cutters and milling machines. Then it really will be my fault…

My most satisfying way of doing CAD in 2-2.5D for laser cutters is writing PostScript code, which allows me to parameterize everything in a sensible way. PostScript becomes PDF, which has a laser cutter driver. Presto.

Perhaps the way to get that kind of control for 3D printing is to drive FreeCAD from Python, or SketchUp from Ruby.

I rather like OpenSCAD, but it is very limiting. I recently wanted to print standard pipe threads, and there’s no helical extrude in OpenSCAD that can do it, so I spent a couple days generating thousands of thin triangular solids in the appropriate locations, hulled them together in pairs, unioned those, then subtracted them from a solid. Doing it in Python would be a lot easier. Furthermore, OpenSCAD takes over an hour on a fast Mac Pro to render the result so you can export to STL for printing! I published my solution on ThingiVerse.

If I ever figure out how to do these simple things simply, I should write a book. Sorry about this rant…

Update 24 February 2015:

AutoDesk Fusion360 Ultimate, currently available at no charge, looks very promising. It’s a rewrite from scratch that combines features of Inventor Pro and some of their other software. It’s a hybrid of a direct editor and a history tree-based editor. It still has some gaps, but works at a very useful level. And, it directly supports generating tool paths for milling machines or routers!

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Sears Craftsman C3 tools work well (only) with Lithium

Wednesday, November 28th, 2012

I’ve been using many of the Sears Craftsman 19.2V C3 series of battery-powered tools for several years now, and have been quite pleased with their performance.

Unfortunately, they generally come with NiMH battery packs, and those I find less than useless (i.e., more trouble than they are worth). For my kind of intermittent use, those packs are usually flat or nearly so when I go to do something, and they seem to have a very short useful life. Sears ought to discontinue them, in my opinion, because they bring disrepute to the whole tool family.

But the big (now middle-sized) Lithium battery packs are great! They hold their charge for very long times, and hold enough energy to do serious work on each charge. I haven’t tried the small Lithium battery packs that Sears now includes with some of the tools–they don’t seem enough cheaper or lighter to be worth the bother. And I’ve just purchased a couple of the new extra capacity 4AH XCP series, but have no experience with them yet. At present, those are selling for the price they used to charge for the big packs.

Over the years, they have had a number of sales of the big Li packs with fast chargers for $89, so I’ve accumulated a bunch. They really have been the key to making the tools useful. Only one battery has failed, and it was covered by the warranty–I rarely purchase the extended warranty for anything, but in this case it was given me as part of an exchange/replacement. I had to struggle to get the promised actual replacement, though–Sears wanted to give me a credit for the (sale) price I’d originally paid, which was not enough to purchase the promised replacement anymore. But I complained and eventually the manager sold me the replacement for that exact amount, so I was satisfied.

The tiny hand vac, 315.115710, is a bit marginal. I think the airflow is just too limited, but they do work. The sound is awfully shrill, though. But I prefer them to my previous hand vacs just because the battery system is compatible with my C3 tools.

A bit bigger and more friendly and effective is the portable wet/dry “canister” vac in this family, 315.175980. It hasn’t always been available to buy, but I now have two of them. I find these quite useful for vacuuming floor edges and corners, webs from ceilings and skylights, occasional localized messes.

I find the inflator, 315.115860, handy for car and bike tires, even though I have an air compressor.

The radio, 315.101260, was a disappointment. It runs the battery down in less than a day’s work. It looks like it has an incandescent bulb to light the dial, which might explain it. Probably they figured the battery was huge so they didn’t have to care about efficiency, but the result is I use a smaller battery-powered (3 AA) radio, which runs for weeks.

The drills are really strong and rugged. A big surprise for me was the impact driver, which I didn’t buy for a long time, figuring the drills were good enough for driving screws and lag bolts. But a construction guy suggested I try one, and now I use it all the time. It is really a lot better for driving screws (or removing them), using its impacts for the hard going part and turning very fast when the going is easy.

I wish they’d add an oscillating tool (like the famous Fein Multimaster) to the family. They have one in the 12v NexTec line, which is very useful, but not as rugged as I’d like. I’ve had trouble with the battery-retaining system, perhaps wearing due to the extended vibration or perhaps softening due to heat, but some battery packs don’t want to stay in by themselves now. The NexTec series are quite usable, but you really have to have extra batteries ready for swapping if you’re going to do serious work with them. I wish the NexTec and Dremel Li batteries were interchangeable. Both are good, and very similar, but it’s not efficient to have separate spares and chargers for both systems.

I’ve also found the NexTec electric hammer useful for odd situations, cramped working areas, etc. It’s awfully noisy, but effective.

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