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If you're mounting something standard, like a serial port, Ethernet port, or whatever, and are doing enough volume to even consider buying a desktop CNC machine, you should call a commercial enclosure manufacturer. They're used to custom runs, have the right punch tooling, and will deliver perfect results.
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Oct 27, 2020 02:50
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If we're talking about Hammond cases, you can buy the cases for like $6 on Digikey, but if you contact them directly and provide drawings, they will CNC them out for you and sell them to you for like $9 total instead. It's bananas how streamlined their operation is. This is in quantities of 50, even. It goes way down when you do more
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Oct 27, 2020 02:57
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That's a great idea. I was hoping to risk throwing a few $100 USD on something cheap and workable, but I think the height requirement alone (let alone quality) will break that. The solution I have now is workable for small runs; just takes more time, and will result in wasted money on enclosures I have to redo. Can assess options better once I know more about volume. edit: Yep - we are talking about hammond cases! That's an outstanding idea. I'm going to try to make 10 or so in the initial batch, post on Reddit etc, then see what the demand is like. Or maybe ask around once I have prototype photos. Rough concept:  I've made some changes since, like moving the ports shown on the left to the back, and spacing them out, since even the drill press can't do holes on the long side, and I need to account for grommets in the spacing. You can see my dremel handiwork on the screen. (And some nasty burn in from mishandling the FPC connector!) Dominoes fucked around with this message at 03:03 on Oct 27, 2020 |
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Oct 27, 2020 02:58
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Dominoes posted:I've made some changes since, like moving the ports shown on the left to the back, and spacing them out, since even the drill press can't do holes on the long side, and I need to account for grommets in the spacing. It's a poor craftsman that blames his tools. You need to fixture the box in the drill press somehow. Even throwing a chunk of wood on the table, turning it out of the way, and then backstopping your "long edge" so you're drilling from the plastic into the wood is better than just free-air drilling. I've made dozens of little enclosures in Hammond boxes in aluminum, ABS, PVC, and whatever garbo acrylic they use using nothing but a drill press, hand drill, and hand files. It may take a smidge longer, but unless you're a hamfisted lummox with no attention to detail, no patience, and a cavalier attitude, it is absolutely possible to get professional-looking boxes in plastic by hand.
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Oct 27, 2020 22:33
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babyeatingpsychopath posted:It's a poor craftsman that blames his tools. You need to fixture the box in the drill press somehow. Even throwing a chunk of wood on the table, turning it out of the way, and then backstopping your "long edge" so you're drilling from the plastic into the wood is better than just free-air drilling. The other trick is to design the pattern in CAD and print it out on sticker paper. Then you've got nice clean lines that show you where to cut/drill/file, and it's easily removed with some heat or iso alcohol. A drill, nibbler, hand files, and maybe some sandpaper is all you really need. However, as soon as you're talking about more than 10-20 (depending on complexity), just have Hammond/Budd/ProtoCase/PolyCase make them. I just ran some numbers through PolyCase's instant quote system, and it's super cheap. A DC-59F enclosure: https://www.polycase.com/dc-59f which is like $12.50 to start with 4 sides of the base needing machining, with 14! total features, plus the lid having 4 features came out to: QTY:1 (stupid money, $238 each) QTY:5 $61 each (still spendy) QTY:10 $38 each (getting there) QTY:25 $25 each (very affordable) QTY:50 $19 each (Now they're cheap) Figure out your time per unit, assume you'll gently caress up some, and it gets very affordable, very quickly. There's a $100 setup fee, but there are other companies. Compare and find out.
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Oct 27, 2020 23:06
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sharkytm posted:The other trick is to design the pattern in CAD and print it out on sticker paper. Then you've got nice clean lines that show you where to cut/drill/file, and it's easily removed with some heat or iso alcohol. A drill, nibbler, hand files, and maybe some sandpaper is all you really need. However, as soon as you're talking about more than 10-20 (depending on complexity), just have Hammond/Budd/ProtoCase/PolyCase make them. I just ran some numbers through PolyCase's instant quote system, and it's super cheap. Agreed. There are a bunch of good tips. I lay my stuff out in CAD, print it at 100% scale, verify measurements, then use glue stick or 3M 77+ to stick the stuff to the enclosure. Use a razor knife to cut on your lines, center punch your holes, drill undersize, file to size.
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Oct 27, 2020 23:25
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I have more 3D printed Hammond cases than real cases at this point, too. Their models print great, and are easier to print with the cut-outs (also proving my design) than cutting them out later
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Oct 28, 2020 03:07
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babyeatingpsychopath posted:It's a poor craftsman that blames his tools. You need to fixture the box in the drill press somehow, instead of discounting that option. Even throwing a chunk of wood on the table, turning it out of the way, and then backstopping your "long edge" so you're drilling from the plastic into the wood is better than just free-air drilling. sharkytm posted:The other trick is to design the pattern in CAD and print it out on sticker paper. Then you've got nice clean lines that show you where to cut/drill/file, and it's easily removed with some heat or iso alcohol. A drill, nibbler, hand files, and maybe some sandpaper is all you really need. However, as soon as you're talking about more than 10-20 (depending on complexity), just have Hammond/Budd/ProtoCase/PolyCase make them. I just ran some numbers through PolyCase's instant quote system, and it's super cheap. babyeatingpsychopath posted:Agreed. There are a bunch of good tips. I lay my stuff out in CAD, print it at 100% scale, verify measurements, then use glue stick or 3M 77+ to stick the stuff to the enclosure. Use a razor knife to cut on your lines, center punch your holes, drill undersize, file to size.
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Oct 28, 2020 18:41
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I want to test my V-carving-with-cutout paths on a few different materials. I have 1/8, 1/4, 1/2" MDF, 1/4, 1/2, 3/4" plywood, 3/4" OSB, and some various thicknesses of solid wood. What I want is to cut out the same model that I've already designed in Fusion 360, and just have some CAM parameter magic to spit out like ten different files for each of the various thicknesses/speeds. Is there a way to parameterize CAM? I am not looking forward to setting up a model for each thickness of material, then a NC program for each combo by hand.
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Nov 5, 2020 01:48
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I think I must be misunderstanding, but if you just change stock thickness on the same model, it'll regenerate your tool paths. If you have different sized X-Y dimensions on your stock, things may get a little hairy. If you *really* wanted the design to automatically end up in, say, the center of your board. I've never milled OSB, so I don't know if there's some trick to it, but I've milled MDF and plywood at the same feeds and speeds (different models, though) and sandpaper is your friend with plywood anyway. Also, please wear a ventilator when milling MDF. It's pretty much made of sawdust and poison.
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Nov 5, 2020 13:37
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babyeatingpsychopath posted:I want to test my V-carving-with-cutout paths on a few different materials. Model and program one, then save as to change the name. Adjust your model by editing your inputs. Don't redraw it, just extrude further. Your toolpaths will automatically adapt to the new geometry. Make sure your selections use stuff like selected contour for the height and you'll be golden.
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Nov 5, 2020 14:21
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I ended up in the "manufacture" space for all of this. I have one model at nominal dimensions (1/4"). I then generated a setup for "relative size box" with side offset 3/16" and top and bottom offsets of 0". I then did all my paths with heights based on "stock top" or "stock bottom." I then duplicated this setup, changed the "bottom offset" in the setup to 1/4" and now the paths are all for 1/2" material. Duplicate again, -1/8" offset, and the paths are for 1/8" material. I used adaptive processes for pretty much everything, so I set my feedrates to 1111, 2222, 3333, 4444 etc. I then wrote a little python script to take "1/4" raw" and spit out "1/4" plywood" and "1/4 MDF" and whatnot by just replacing all the feedrates with stuff out of a table. Not as elegant as having a bunch of parameters, and if this gets into dozens of ops (instead of 1 engrave, 2 holes, and a cutout) this may get unweildy.
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Nov 6, 2020 14:55
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hi thread, I am currently running an upgraded 3040 to do mostly 6061, ultem, peek, and edm graphite what’s the consensus on an inexpensive lathe to turn into a cnc lathe? I want to do ultem turned parts and the occasional 6061 part, max diameter 2”, max length 6”. I have spare steppers and controls aplenty.
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Nov 8, 2020 13:40
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Just bough a CNC router. The cheapest one I could find on Amazon. I accept I'm a poor craftsman, and gave up on finding a CNC for tall surfaces in my budget. (Drill press is ok for most of the connections there), and am relegating CNC for cutting narrow cutout where a ribbon cable goes on a short surface. (pictured at the top of this page) The good news, is, it works way better than hand-dremeling. I put plywood under the ABS piece, and use the manual controller (might try software later). To cut plastic neatly without melting, you need to use slow bit speed speed, and in the case of CNC, move the bit laterally quickly. The problem is, this device doesn't seem to have a torque control; I think it's just applying different voltages or PWM to a motor with the bit directly mounted. This means that it seizes up when moving laterally if not at full rotation speed. Do I need an aftermarket gearbox? Thank you. For context, the drill press uses a belt to change speeds, and runs the motor at one setting. So when I set the belt to the lowest speed, and get loads of torque. Btw, sharkytm's sticker paper trick for the drilled holes works great! Going to try having Hammond machine the case after I demonstrate there's enough demand to make it worth the min qty. Dominoes fucked around with this message at 01:45 on Nov 12, 2020 |
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Nov 12, 2020 01:37
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Dominoes posted:I think it's just applying different voltages or PWM to a motor with the bit directly mounted. This means that it seizes up when moving laterally if not at full rotation speed. Could you post a video. What do you mean it seizes up?
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Nov 12, 2020 01:45
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Sure. I'll take a stab at video. It just gives up, like when your dremel's low on batteries.
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Nov 12, 2020 01:45
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Video: https://imgur.com/kEMl0sa At full speed, the result is acceptable, and the best solution I have so far, but is not ideal. Ie a cut like one of the top 2, sanded, and concealed under the display. Dominoes fucked around with this message at 01:54 on Nov 12, 2020 |
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Nov 12, 2020 01:51
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Looks like your part is slipping in its fixture. Look at the length of the slot wrt the wing nut. Also You're plunging straight in, are you sure that is a center cutting endmill?
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Nov 12, 2020 01:53
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It is, but isn't that a (mostly) independent problem, or a consequence of the bit seizing, vice a cause?. (Ie: You push into a block of cheese with a dowel, vice a sharp knife. Won't it be pushed more by the former?)
Dominoes fucked around with this message at 01:57 on Nov 12, 2020 |
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Nov 12, 2020 01:54
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It's hard for me to tell in that video, but from personal experience I can say it's worth double checking you've got everything wired correctly so that the spindle doesn't spin the reverse of the way you want.
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Nov 12, 2020 02:00
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Dominoes posted:It is, but isn't that a (mostly) independent problem? OH I just noticed that your spindle straight up stalls. See above edit, are you sure that's a center cutting end mill? I havent cut much in the way of plastics but that mode of operation would destroy an endmill in aluminum. Even if it is a center cutting endmill you probably want to helix or ramp down into your cut. If it were me I'd try actually calculating out what I want to do and camming it up so I know I am getting the correct feeds. Assuming that is a 2 flute end mill, some soft unfilled plastic and 1/8" Diameter, you should be feeding it in the .003-.004 IPT range. Im guessing that can't get anywhere near the needed RPM so you'll have to do the best you can...motors have torque curves, if you're stalling yours you might want to try 70-90% of max RPM at a small depth of cut (DOC) Trebuchet King posted:It's hard for me to tell in that video, but from personal experience I can say it's worth double checking you've got everything wired correctly so that the spindle doesn't spin the reverse of the way you want. It appears to be turning clockwise and and the helix appears to be the correct direction to turn clockwise.
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Nov 12, 2020 02:04
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All of this assumes that's a 3018 pro. If so, then your available range of spindle speeds are 700-1000, referenced to a max of 1000. These numbers have no relation to actual RPM unless you've measured it. These things have a "10k rpm" spindle by default. At 24V and no load, I measured mine at 10760 RPM. Not too shabby. RPM scaled linearly at no load down to 50%, then not so much linearly down to 30%, where it stopped self-starting. That said, I'd run it to 100% RPM, plunge 2mm into a piece of MDF at feedrate 100(mm/min), then use the jog to drive 30mm (still feed 100). At 100% (M3S1000) I was getting 9700RPM. At S800, I was getting 7600RPM. That's not 80%, but close. At S700, it was 5100RPM. Below that, it was straight garbage. You need to do something like that to test what actual feed you can run. Keep your spindle above 70%, 100% preferable. Plunge down, then use the jog keys to just drive around in the plastic at various feedrates and find something that works at all.
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Nov 12, 2020 02:42
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No idea if it's a center cut. I don't know how the bits work, but ordered more marked as appropriate for plastic. Could always pre-drill a hole at starting point if they only cut laterally. I've seen different bit styles also marked for that, like ones that aren't twisty. With small cut depth, how do you cut through the whole thing? One layer at a time? It's ~2-3mm thick. Nailed it re 3018. That's great intel - sounds like I may need to just keep max speed and go with the melting. And make the cut as quickly as possible. Ideally, it would work at slow rotation speeds with more torque, if I understand the plastic-cutting guides I've read, but I don't think my router can do that. Will have a look at the software next. Much appreciated dudes!
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Nov 12, 2020 03:34
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Dominoes posted:No idea if it's a center cut. I don't know how the bits work, but ordered more marked as appropriate for plastic. Could always pre-drill a hole at starting point if they only cut laterally. I've seen different bit styles also marked for that, like ones that aren't twisty. With small cut depth, how do you cut through the whole thing? One layer at a time? It's ~2-3mm thick. Post a picture of the end of the endmill or find one online. Here's an example though:  Basically it should have a sharp edge all the way to the middle. (There's more to it than that end mill design wise but that'd good enough to start) 3mm should be fine in one go but hard to really diagnose without being there. Theres a hand full of strategies to cut all the way through but yea one layer at a time is a pretty common one. If you're full-width slotting, I like to ramp back in back and forth like this: 
CarForumPoster fucked around with this message at 03:45 on Nov 12, 2020 |
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Nov 12, 2020 03:42
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The correct end mill for soft plastics is the sharpest single-flute tool you can find; too many flutes, or a dull tool, will build up heat and melt the part. Straight flutes will minimize lifting. https://www.amazon.com/Freud-Single-Flute-Straight-03-140/dp/B00004T7AX Run it at maximum spindle speed with an aggressive chip load (i.e. fast feed). Don't plunge straight down; program in a vertical ramping move outside the part, or do a helical entry. Consider cooling/lubricating the part with soapy water. Sagebrush fucked around with this message at 03:51 on Nov 12, 2020 |
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Nov 12, 2020 03:48
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Awesome. Diving into the software now. Bought that bit, and will try ramp. I like the cooling idea too. Something to draw heat away from the cut should help. I think the plywood support is also doing double-duty there. (A poor conductor, but better than air!)
Dominoes fucked around with this message at 03:57 on Nov 12, 2020 |
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Nov 12, 2020 03:52
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To expand a bit, the main things you are concerned about when machining plastic are the material deforming under cut forces, the material overheating and melting, and the chips getting whirled around and melted onto the bit. To avoid deformation, you need to use an extremely sharp tool so it slices cleanly with little force. A dull tool will put a lot more force on the stock before it starts to cut. The sharpest tools you can get are high-speed steel, but a brand new carbide tool will work fine. Obviously also doing a shallower cut will reduce tool force. To avoid melting, the sharp tool will help again because it reduces cut energy. However, you still need to carry heat away somehow. The way you do this is with the chips. Setting an aggressive feed rate will make big chunky chips that have (relatively) lots of thermal mass, so they carry heat away instead of letting it build up in your part. Paradoxically, this means that plastics cut better when you machine them faster. You can also cool the part with a suitable coolant, like WD-40 or soapy water. Don't use alcohol, especially on acrylic. If the chips stay in the cut zone, the tool will mash them around and they'll build up on the edge and it will be awful. You need tons of clearance around the chip so that it detaches cleanly and gets thrown out. A single-flute cutter has the most relief and thus works better than multi-flute tools (though you can usually get away with two). You can also look specifically for O-flute tools, which have a hollow grind on the edge for the best performance. High chip loads will also make big chips that bounce away instead of small ones that stay in place, and a coolant flood or compressed air blast can help flush everything out.
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Nov 12, 2020 04:10
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Much appreciated! I've already hit all 3 of those issues. The whirl-around-bit thing happened on both the CNC and dremel. I assume I need to melt it off with a hot air gun or something. Ended up switching bits instead. It sounds like the ramping technique, and that sharp bit you recommend will be a big improvement over my naive approach. It's also becoming clear that software allows clever techniques and precise control; not just automation.
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Nov 12, 2020 04:12
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So, I found the G-code. Does this look to be the right approach for ramping? Waiting on the single-fluted bit before trying it, although I did test on the machine with it running. Also need to come up with a plan for calibrating (?) mapping the CNC coords to real coords. Making sure it starts at the right point rel to the table and part etc.  For a cheap machine, this is actually pretty cool! It was easy to assemble, connect to computer, and program. I wish it could do tall parts so I could machine other parts of the enclosure. Dominoes fucked around with this message at 00:03 on Nov 13, 2020 |
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Nov 12, 2020 23:55
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Conceptually that sort of ramping is fine, though I can't speak to the specific values you're using. 1 in 10 is a reasonable angle though. On line 5, bring the tool down to like 0.2 above the surface instead of right on it, so the ramp starts in the air.
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Nov 13, 2020 00:15
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Done
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Nov 13, 2020 00:16
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Tim Thomas posted:hi thread, I am currently running an upgraded 3040 to do mostly 6061, ultem, peek, and edm graphite I converted a grizzly 8x16 lathe, but if I had to do it again, I would have picked vintage iron to really gently caress up. I'd be a better machinist today if I'd spent the time fighting my DIY machine, fighting stock on a tormach, but I'd also be a much worse mechanical engineer. Make sure a DIY CNC lathe is a battle you both need and want!
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Nov 13, 2020 09:40
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Mofabio posted:I converted a grizzly 8x16 lathe, but if I had to do it again, I would have picked vintage iron to really gently caress up. I'd be a better machinist today if I'd spent the time fighting my DIY machine, fighting stock on a tormach, but I'd also be a much worse mechanical engineer. Make sure a DIY CNC lathe is a battle you both need and want! I do machine automation for a living so realistically I’m looking for validation that a cheap 8 x 16 can be converted over and actually do aluminum and PEI parts without it being a complete assache to machine.
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Nov 13, 2020 21:32
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So I broke the new bit trying to remove it from its packaging using pliers, then realized it doesn't fit the chuck anyway, but got ordered a new set of similar ones at various sizes, and got the best-yet results using the program above with the swirly bit. I need to figure out a system to consistently and quickly position the part so it's the same place every time.
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Nov 14, 2020 03:27
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Tim Thomas posted:I do machine automation for a living so realistically I’m looking for validation that a cheap 8 x 16 can be converted over and actually do aluminum and PEI parts without it being a complete assache to machine. Yup, it loves aluminum. Has rigidity for 12L14 and 1018 if you don't do anything too silly.
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Nov 14, 2020 03:28
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Dominoes posted:I need to figure out a system to consistently and quickly position the part so it's the same place every time. Machine yourself a little corner bracket or something that you slide the stock into before clamping it down. Or just put a couple of bolts into the table and push the stock up against them.
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Nov 14, 2020 03:56
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That sounds one step too close to self-replicating robots that consume all available energy, leaving our star system cold and dead.
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Nov 14, 2020 03:58
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Dominoes posted:That sounds one step too close to self-replicating robots that consume all available energy, leaving our star system cold and dead. Y'all heard of RepRap?
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Nov 14, 2020 05:53
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Dominoes posted:That sounds one step too close to self-replicating robots that consume all available energy, leaving our star system cold and dead. Don't worry, Stargate SG-1 took the replicators out already.
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Nov 14, 2020 10:21
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| # ? May 31, 2024 00:33 |
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Mofabio posted:Yup, it loves aluminum. Has rigidity for 12L14 and 1018 if you don't do anything too silly. excellent, that sounds like the right thing to do then. that is, if I don’t let the fuckin this old Tony 4th axis video convince me to do it that way....
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Nov 14, 2020 14:10
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