Not hard to make a variable pitch screw. A straight strip wound around a rod makes a constant pitch. A curved strip wound around a rod makes a variable pitch. Multiple strips stack-wound to make deeper flutes but still easily formed.by murrayd - General
There's an open-source modeler called NaroCAD that's been consistently developed by a core group. They've got a blog, narocad.blogspot.com where they post "nightly builds". It has a direct-edit workflow, faces are profiles that extrude and it has a well-integrated sketching that'll also extrude if closed. It's not unlike Autodessys's Bonzai3D. It's a lot of fun and probably a more intuitiveby murrayd - 3D Design tools
Read it and had to try it. Excellent! RTV molds within four hours. It's still sealant so if you add only a little cornflour it still sticks like poo to a blanket, so you've got to experiment with PVA or silicon release agents, but with more cornflour it starts to cure pretty rapidly, so doesn't stick so well to non-porous items, allowing you to be less fussy about release. Lots of potential wby murrayd - General
I used to work for a company that made pool furniture from PVC piping. The pipe was cut with a commonplace drop saw, and the swarf that the saw cut was granular, about 3mm in its greatest dimension, regular and clean. Chinese-manufactured domestic drop saws are inexpensive. I think one would be a pretty good starting point. Ganged common tungsten-toothed saw blades in the throat of a chuteby murrayd - General
3D Systems bought up the assets and IP of Desktop Factory when they ran out of venture capital. Desktop Factory's idea is similar to a laser printer, but with a roller transferring powder layers fused with a spot from an intense visible wavelength halogen bulb rather than a laser. It would surprise me not at all if that turned out to be their next development direction. It doesn't detract froby murrayd - General
I used to build plastic construction model kits, which often require sanding, at the joint seam of aircraft fuselages, for example. I used to load a soft brush with lacquer thinners and just flow it along the sanded area, matt in comparison to the mold cavity finish. The thinners will reflow the surface. Dipping your ABS component or putting it on a rack and pouring the solvent over it is pretby murrayd - General
Netfabb slices too (right-click, "export slices"), and has an animation player that plays them successively. Dead simple configuration of layer thickness and apart from screen capture, at least one of the slice formats it outputs to is a simple, human-readable polyline list, viewable in any number of free or commercial CAD programs.by murrayd - 3D Design tools
Charles Hull, one of 3D Systems' founders, was the guy who invented stereolithography, and the .stl file format. Isn't that what you guys are building on here? Have you felt threatened by them? They might be big, and they're the grandaddy of RP, but that doesn't make it possible for them to corral open-source software or hardware as their own proprietary, or indicate that they want to. In faby murrayd - General
I reduce the amount of mechanical finishing by flowing cyanoacrylate glue over pieces. The discount stores here in Sydney sell ten 3g tubes of cyano for $2. Capillary action carries it along the steps, and a whiff of accelerator sets it. A first application "fillets" the steps, subsequent applications fill them, and it's very controllable and pretty quick. Accelerator is stinky, so I do it ouby murrayd - General
If something breaks down on the z axis, the thread won't let the head descend onto the workpiece through force of gravity, which a direct-drive belt might allow. My adaptation uses a cable parallellogram to maintain z axis alignment with one z-screw, which only needs a single short belt from the stepper to the threaded rod - or a gearset, if there's one handy, say from a discarded printer - andby murrayd - General
Depending on the ratios, which affects how many teeth are being expected to contact at once, you can separate the pitch circles and adjust the addendum and dedendum (flank profile outside and inside of the pitch circle) to strengthen the teeth, turn down the outer diameter to produce stub teeth, or both.by murrayd - General
Viktor's right. The profile is tapered to the intersection point of the gears' axes, which is the extension of their shaft axes. Because of the taper, profile-correct conical involutes can't be hobbed or cut with a tool on a single axis, those you buy are approximations.by murrayd - General
Michail: In simple terms of 3D geometry creation, TurboCAD or Punch Shark are as capable as SolidWorks, ProE, NX or Catia. With qualification, as you'd expect for the relative pricing. For parametrics and sheet metal, Alibre. Sarcasm, yes.by murrayd - 3D Design tools
Cefiar, my experience is in Sydney, so I guess there's some variation in distribution. But you're right, metric is pretty widely available from industrial suppliers, and they do seem to be more common than elsewhere, if the comments from builders in other parts of the world are anything to go by.by murrayd - General
Bunnings have galvanised threaded 8mm bar suitable for the frame members. The galvanising is good quality and smooth, gal nuts don't bind on it, and the studding is 1.2m in length, so only 5 lengths are needed. At $5.75 a length, pretty economical. I bought drawn smooth bar from a stainless supplier. Not ground, but straightness was within .2mm over the axis travel, diameter and smoothness rby murrayd - General
Michail Wrote: ------------------------------------------------------- > I have a TurboCAD license for simple 2D sketching. > Featurewise similar to AutoCAD LT but less > intuitive and quirky. Can't beat the price though > - I got an old version for €50. They brag about > 3D but that aspect is entirely useless. > > I know naught about Unigraphics, nor about Solid > Edge.by murrayd - 3D Design tools
Arvin Wrote: ------------------------------------------------------- > > I bought some 50lb test braded fishing line. No > luck. It started out great but seemed to flatten > and then rolled up on the other layers. Still > worked but the steps would not be the same length > for those versus the lower layer. > > My next thought is kite string. I'm worried it > will doby murrayd - General
HeeksCAD, freeCAD, NaroCAD and CAD Exchanger will convert IGES and STEP files to STL, if your CAD program doesn't do STL directly.by murrayd - General
I suggest a troubleshooter area in the wiki, Sebastion. If similar issues are listed together, along with a workthrough and resolution, if arrived at, patterns will reveal themselves, whatever the parts combinations. Makerbot, as a commercial operator, have statutory warranty and support obligations as well as sustaining their business through maintaining their reputation. Independent Darwin anby murrayd - General
I worked for a company that produced heating wires from stainless steel and bronze. Wire work hardens as it's pulled through successive dies and a 20% reduction in cross-sectional area hardens it from soft annealed to spring-hard. If it needs to be further annealed, it's drawn slowly through a furnace in the absence or oxygen. Because the ends of the furnace are open to allow the entry and exiby murrayd - General
Spaceclaim is around USD 750 starter. I looked at Think3 about six or seven years ago, when they were leasing the software. At that time they charged USD 2000 per year. I believe they sell the licenses now, but parametrics aren't part of the lower end packages.by murrayd - 3D Design tools
Peel the waste off the roll instead, which would make undercuts more difficult but feedback positioning easier.by murrayd - General
The software's not too much additional complication, Viktor. A slice is a boundary intersection, your proposal additionally intersects each slice with an involute developed from a circle having a diameter which is the thickness of the material. It would be a bit of a bear unless there's constant feedback on the thickness. Unless it's self-correcting, a material thickness error compounds as anby murrayd - General
Netfabb does that. Embed the model in a block, subtract it from the block, and the sliced result is an LOM toolpath. Ten seconds. How long do you want it to take? Viktor, the waste can be left attached by two or three mm "runners", and sliced to separate in halves, as in this picture. I've drawn the cuts as wider slots for clarity, it's one layer of a sphere, cylinder or cone. FYI, there'by murrayd - General
Netfabb won't help you with that. A slice is a polyline, a series of vertices. When you create g-code, you're drawing that polyline with the machine - but if you've got an extrusion that's .5mm wide and you've got an absolute perimeter outside size, you've got to recalculate the offset path, which is what the g-code refers to. Then the infill passes have to be added as additional paths. If yoby murrayd - General
.slc files ARE toolpath files, because an LOM machine has no tool offset, so all the software has to do is the very simplest post-processor stuff: x,y position. Netfabb generates .slc files from .stls automatically already. Right-click in the window, choose "Export as slices", set the thickness and tolerance parameters and file extension, and off it goes. It also does animation of the file it'by murrayd - General
It can be done in a g-code generator like Skeinforge or any other, the parameters are that if the g-code is compared to subtractive, there's no tool offset or waste passes, if it's compared to additive, there's no inset for extrusion thickness or infill. .slc is described here, , and it can be seen from the description that it's easily formatted as it's easily human-readable, an .slc file couldby murrayd - General
3DSystems, whose founder Charles Hull devised .stl format, also came up with .slc file format, probably with LOM in mind. It's stacks of 2D polylines, the outline of each layer. Like 2D g-code, without having to be written as g-code, because many CAD programs will give profile series through a model that can be directly formatted for the layers.by murrayd - General
I've just received some steppers from a seller on ebay (in the US) who trades as "steppersource". I bought some 400 steps-per-rev Vextas from him because I aim to start with a g-code driver board I've already got, but it's unipolar and doesn't microstep. I'm not too concerned about torque, although these are little more than half the torque of equivalent 200-steppers. The seller has a wide raby murrayd - General
There's a geometry flaw in the stl of Mendel's frame corner bracket. I think that it'll mean that one of the outer nut and washers isn't bearing on a flat surface, which could lead to cracking when tightened. As well, the brackets aren't mirrored about the geometry. If they aren't compared and aligned alike at assembly, although the geometry will be right, it'll rock on a flat surface.by murrayd - General