About that 8GB Raspberry Pi4. I think it might be over kill for a machine controller unless you like runing a webbrowser and waching Youtube whie the mill is cutting. Notice the 8GB is $75 and the 2GB is $35. There is a robotic list I'm on ad the question was Which is faster two $35 Pi4 or one $75 Pi4. I am very sure that for the robot use case I'd get better performance for $70. Likley also for the machinist who wants to watch Ytube whie cutting metal, Save $5 and get twice as much CPU power.
The $75 8GB Pi4 is perfect for the person who wants a desktop PC. That is the target user for this. If yu need a cheap PC Yo can buy quad-core Xeon systems for under $100 now https://www.newegg.com/hp-proliant-dl380-g7-639828-005-rack/p/N82E16859107039 The Pi4 is great if you have very limited space or must run on battery power. Good for robots. But I don't see the point if there is an AC mains wall socket nearby. and you are installing inside something as big as an office. These 1U size servers are selling for pennies on the dollar when they come off-lease and are PERFECT for industrial uses like CNC. After downloading the part's CAD file. You import it to your CAD software. You have a wide choice in selecting CAD software. I use Fusion 360. Fusion runs only on Windows and Mac. For a Linux system the best option is https://www.onshape.com and many people will argue it is simply the best option in any case. I'd argue for Fusion if you also have CNC tools. Either is a full pro-level solution. My test for choosing CAD is to ask yourself if you could see yourself making something as complex as a cordless drill after 4 or months of study. Very few free CAD systems are that good. After re-working the file to make it better fit your needs save it as an STL. If you download a part it might need modification to make it easier to print. For example, the timing pulley has a slightly concave top surface. I made it dead-flat so that I could print it on a flat build plate with no support under it. I wanted thicker flanges too as the 1.5 mm would be fine in metal but to flexible in plastic. The set screw was M3 and in plastic M4 is better. Some times the part is awkward to print and has to be cut, printed and then glued. In general you need to be decent with your CAD system. All good CAD system have on-line classes and it is worth doing them. CAD files are editable and contain the structure of the part and have things inside line "M4" size threads and filets and logical stuff. STL is "just triangles" and all the "designer's intent" of the part is gone. STL files are just approximations of the shape with zero structure. So saving to STL is a one-way process. Yes STL is only an approximate shape as all the curves are converted to triangles. Next you need to turn STL into g-code. Everyone here knows what g-code is. But for printing the printer makes layer after layer each about 0.1 or 0.2 mm tall. so the g-code files are huge with millions of lines of code. You need "slicer" software. Again there are many. I like "Cura". Cura runs on Window/Mac/Linux. Cura allows a beginner to use some defaults and is very much automatic. but also you can find HUNDREDS of parameters and editing options to make changes to the way an object is printed. The STL file only defines the exterior surface. Cura allows you to specify which side is up and down, the skin thickness and what is to go inside th object. you can set quality, speed and temperatures and well over 100 other things. Then they added the abilty to have different setting for different parts of the object so now I find I use thicker plastic for areas with more stress. Then yu need to get the g-code into the printer. Most printers will have a slot for an SD card. Copy the g-code to an SD and walk it over to the printer. Yes you can connect the PC to the printer with USB but do you really want to tie up a PC for many hours? Just use an SD card and there is then ZERO chance a PC glitch will ruin an hours-long print. Printing from an SD card is more reliable. Back to the sproket. Of late I just hollow out the gear or pulley with a (say) 20mm hole. Then make a 20mm OD bushing to fet the shaft in metal. Press fit the two together. I've not found a reliable way to transfor torge from a 6mm metal shaft to a PLA printed gear and have it last. My next idea is to buy a steel bolt with a hex head and make the bushing from that so I can print a hex shat to fit the head. In any case metal hubs work best and plastic gear tech work surprizinging well. my plastic gears tend to fail at the hub. On Fri, May 29, 2020 at 11:22 AM Thaddeus Waldner <thadw...@gmail.com> wrote: > > > I've dl'd that sprocket file, now what do I do with it to make a > > printable .stl? _Unpack it, see openscad mentioned, install openscad and > > friends, explore. For single sheeve, looks great. Obviously will need > > to figure out how to do hubless & bolt 2 together as central idler over > > a pair of skate bearings. Looks as if it should work if the printer > > does its job. > > I believe you need to render the part, then export the .stl. That file is > pretty well documented and I suppose after a lot of the “explore” piece, a > guy could get fluent in that language and coax it to build ideas. Me, The > biggest thing I’ve done is modify this file to create a custom belt profile > for a replacement pulley in a sewing machine. This company went with a belt > that looks like a HD profile but with a 0.2” pitch... > > > > > Probably watching paint dry fun. :-) A potential problem, possibly > > fixable by putting the grub screws at 180 degrees, is the double d-flat > > on the worm shaft unless theres an option to do that to a round hole. > > I used a pair of screws at 180 degrees to keep the pulley from flexing > sideways too much when it’s clamped. > > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > -- Chris Albertson Redondo Beach, California _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
