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There's no insertion point for the wire so my guess is it's two separate pieces.
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Dec 23, 2022 17:18
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Yea two pieces, there's like .0003"/side between them. Also I ran a bunch of skim passes and then surface ground the top and bottom.
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Dec 23, 2022 17:20
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ante posted:Yo, I run all 3D printed change gears in my 7x14 Chinese mini lathe. They're totally fine for all my aluminum threading. I've crashed it, and the keyways strip out really nicely, saving the rest of the machine. It's a feature. What material do you use? I'm about [this] close to buying a mini lathe, and I also conveniently have some 3D printers. Making custom change gears is something I hadn't even considered and I absolutely love the idea.
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Dec 23, 2022 18:29
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I use PETG for everything. I'm sure other materials would work fine, too.
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Dec 23, 2022 18:34
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Awesome, I was just curious whether you ended up having to use higher-temp stuff like nylon. PETG is easy like pie. Thanks!
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Dec 23, 2022 18:56
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ante posted:Yo, I run all 3D printed change gears in my 7x14 Chinese mini lathe. They're totally fine for all my aluminum threading. I've crashed it, and the keyways strip out really nicely, saving the rest of the machine. It's a feature. What are you using for your 3D printer and design software? I have an original Elegoo Mars and am familiar enough with Blender that I could probably design and print gears, but I've found that the Mars is not dimensionally accurate on larger pieces. I'm guessing that is due to pulling forces stretching the print.
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Dec 23, 2022 21:04
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ante posted:I have unlocked arbitrary thread pitches. New thread title?
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Dec 23, 2022 21:09
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SkunkDuster posted:What are you using for your 3D printer and design software? OnShape and a Prusa i3. Any CAD software is fine, or if you like, I could just send you a set of STLs or my parametric gear generator file in OnShape.
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Dec 23, 2022 21:21
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ante posted:OnShape and a Prusa i3. Any CAD software is fine, or if you like, I could just send you a set of STLs or my parametric gear generator file in OnShape. I'd appreciate it if you could email the stl files to myusername@gmail.com. They might come in handy down the road if I get a filament printer.
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Dec 24, 2022 02:20
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I was actually going to throw them up on Thingiverse, but of course someone else has already done a great job: https://www.thingiverse.com/thing:180038
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Dec 24, 2022 02:28
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SkunkDuster posted:What are you using for your 3D printer and design software? UV resin shrinks when it cures, often by a lot, and also not necessarily at an even rate throughout the part. Seven to nine percent shrink isn't at all unusual for your typical "ABS-like" hobby resins. For low shrink and best dimensional accuracy, you usually have to plan on shelling out the cash for a proper engineering resin, which is expensive enough that just buying some gears would probably make a lot more sense for you unless/until you get that filament machine.
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Dec 24, 2022 13:04
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Acid Reflux posted:UV resin shrinks when it cures, often by a lot, and also not necessarily at an even rate throughout the part. Seven to nine percent shrink isn't at all unusual for your typical "ABS-like" hobby resins. For low shrink and best dimensional accuracy, you usually have to plan on shelling out the cash for a proper engineering resin, which is expensive enough that just buying some gears would probably make a lot more sense for you unless/until you get that filament machine. I've had this problem and used Simplify 3D (which just came out with a new version after many years somehow) to simply increase the size of the part by x% until things started coming out at the size I designed. There might be a more scientific way to do things but this was close enough not just for a specific part (brackets in this case) but several variations of those parts printed at the same percentage increase in the same material/shells/infill settings.
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Dec 24, 2022 16:06
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No, that's pretty much how they do it in industry. The shrinkage is characterized and the model is oversized as needed before printing. They might start with a calculated number, but the shrinking usually isn't isotropic so there will be a series of adjustments that depend on the part's specific geometry.
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Dec 24, 2022 16:09
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Hadlock posted:New thread title? 
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Dec 27, 2022 05:42
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Anodized penetrators had a good run.. But now it's time for pitching.
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Dec 27, 2022 06:29
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Long time no see, posters. For printing gears on a resin printer I highly recommend Siraya Tech’s Mecha White resin, it’s formulated for producing mechanical parts with low wear rates and low friction. It’s got some hard-wearing and… lubrificious??- mineral filler that produces a hard-wearing and slick interface surface after a short break-in period. It’s analogous to the work-hardened faces you get with metal mechanical parts; normally resin prints never ‘stabilize’ in this application and just continually wear down, with the worn-away resin dust acting like an abrasive powder to speed the process. It also prints with good detail and acceptable shrink that is fairly easy to compensate for with some test pieces. Ambrose Burnside fucked around with this message at 21:44 on Dec 27, 2022 |
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Dec 27, 2022 21:34
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Also: anybody got any experience with milling chromium-cobalt alloys? I’m running a mill farm that produces a lot of dental appliances, and we’re gonna expand production of CoCr alloy parts soon, and it’s a little outside my comfort zone with machining so I’m looking for some general wisdom or cautionary notes. Found out the hard way that it’s a very “grabby” material that’ll yank an end mill out of true if the collet isn’t tightened down very well, for example.
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Dec 27, 2022 21:39
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triple-post special: another option to produce even better gears starting with a resin printer is 3d printing molds for the gears you want, and casting them from a tough + stiff plastic epoxy, a steel-filled castable epoxy, or even a low-melt tooling alloy. the nice thing about casting an alloy into, say, molds printed in Siraya Tech Sculpt Ultra (can take 250C+ heat without damage iirc) is that you can reuse the alloy infinitely if the gears strip or wear down. Just choose a lead-free option so tbe gear wear isn’t producing lead dust. You can also produce a lot of neat little custom tools with this workflow, for example I printed myself some custom-sized reamer molds, and can now cast short-run recyclable tools as needed, here’s an unsharpened d-reamer fresh from the (broken, made it too thin) mold:
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Dec 27, 2022 21:48
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Do you have any specific suggestions for casting materials? The whole point of the 3D printed change gears is that they're quick and dirty and Good Enough so I'm not that interested in casting for that application. But for other stuff, I'm very intrigued
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Dec 27, 2022 22:06
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ante posted:Do you have any specific suggestions for casting materials? i was posting a ton about this maybe a year, year and a half ago, searching any of my old posts for “fusible” or “eutectic “ or “alloy” should get you most of it. I’ve mostly worked with two rotometals alloys https://www.rotometals.com/low-melt-fusible-alloys/ -a lead-free 60/40 tin:bismuth called 281-338F, and a lead-antimony-bismuth-tin called 217-440F. i use the former for decorative castings and trinkets people are likely to be handling, plus some lower-stress tooling; the latter alloy is much stronger + harder and is also creep-resistant, making it an ideal tooling alloy for applications like short-run hydraulic press dies for sheet metal, tools that need to hold an edge or fine detail, etc also the lead-free alloy is special because it is essentially dimensionally stable, which is usually not the case for these weird fusible alloys, so you can produce very accurate replacement parts, use it as an intermediate medium for some very neat processes like electroforming copper or nickel over a melt-away electrically-conductive mandrel, etc. the 281-338f met most of my needs, casts with remarkable detail into properly pre-heated molds, and has a nice silver lustre out of the mold, and ofc is lead free. it’s brittle and weak by basically any metal standards but dramatically outperforms anything you can directly print, and the material cost of new tooling is negligible once you’ve bought your ingots b/c it all gets recycled. having to re-cast tools after 15 uses vs 50 is generally worth not having to contaminate my entire casting setup with lead, imo, so i’ve relegated the lead alloy to sheet metal forming dies, where the creep resistance is absolutely essential. to cast this stuff well you need a solder pot and a good high-temp thermocouple for getting the alloy to tbe right pouring temperature without overheating, plus some sort of basic preheating oven for the molds, any toaster oven is more than sufficient. it wants to freeze in molds very badly so you gotta give it every leg up you can there, but once you do get everything at the happy temps it wants it’ll fill even very thin-profile molds with perfect fidelity. Ambrose Burnside fucked around with this message at 22:38 on Dec 27, 2022 |
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Dec 27, 2022 22:34
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Ambrose Burnside posted:Also: anybody got any experience with milling chromium-cobalt alloys? I’m running a mill farm that produces a lot of dental appliances, and we’re gonna expand production of CoCr alloy parts soon, and it’s a little outside my comfort zone with machining so I’m looking for some general wisdom or cautionary notes. Found out the hard way that it’s a very “grabby” material that’ll yank an end mill out of true if the collet isn’t tightened down very well, for example. I work with stellite, but grinding. It can be gummy to work with, you can run into built up edge on your tool. Oil coolants tend to be better at preventing this. It can work harden in an unpleasant manner, so watch your DOC and be sure you don't rub it.
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Dec 28, 2022 00:51
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Ambrose Burnside posted:Also: anybody got any experience with milling chromium-cobalt alloys? I’m running a mill farm that produces a lot of dental appliances, and we’re gonna expand production of CoCr alloy parts soon, and it’s a little outside my comfort zone with machining so I’m looking for some general wisdom or cautionary notes. Found out the hard way that it’s a very “grabby” material that’ll yank an end mill out of true if the collet isn’t tightened down very well, for example. The best suggestion I can give you is to keep detailed records of the cost of scrap so you have a solid case to present to management about no, we really do need to change the tooling this frequently and it costs you more not to
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Dec 28, 2022 03:23
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Dumb newbie question: Looking at fabricating some replacement anchor points for a cargo barrier I bought; I'll need to tap M10 and M8 threads into 2 and 4mm steel. Found this set of cheap bits on eBay: link Can I use my Makita power drill or will I need access to a drill press? For context, I'd love to have a drill press and quality set of bits, but I am moving abroad in 6 months and have to get rid of all my stuff. Weight will be really tight moving so I'm not even keen to take the bits with me.
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Jan 2, 2023 22:32
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Ethics_Gradient posted:Dumb newbie question: I wouldn't recommend getting those combination drill and tap things. You'd be better off picking up individual drill bits and their respective taps and maybe a tap wrench, depending on how much cost is a factor for you.
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Jan 2, 2023 22:48
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Ethics_Gradient posted:Dumb newbie question: You're better off with a drill bit and matching tap. To drill you want to be in high range, and to tap in low range. No drill press needed. Even if you had a drill press you'd need to switch speeds or hand tap.
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Jan 2, 2023 22:48
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A Proper Uppercut posted:I wouldn't recommend getting those combination drill and tap things. You'd be better off picking up individual drill bits and their respective taps and maybe a tap wrench, depending on how much cost is a factor for you. Yooper posted:You're better off with a drill bit and matching tap. To drill you want to be in high range, and to tap in low range. No drill press needed. Even if you had a drill press you'd need to switch speeds or hand tap. Ah, gotcha. I do have a set of step bits already I could use for the holes, at least. Glad I don't need a press! Actually seems kinda hard to find just taps that don't have the drill bit on the end (at the low end of the market). I found this set - my socket set does have something that seems similar to a tap wrench that I think I could use. The seller doesn't indicate whether it's 1/4" drive or what, but I assume I've probably got a suitable adapter on hand. Followup question: I was planning on sourcing the steel from the tip - any recommendations on what to look for/does it matter? It will be secured against the interior body panel of the van. I do have a decent half-face respirator to work with if it's galvanized (not sure if it gets hot enough cutting vs welding to produce harmful fumes, but figure can't hurt to be safe). Ethics_Gradient fucked around with this message at 23:45 on Jan 2, 2023 |
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Jan 2, 2023 23:15
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Ethics_Gradient posted:Ah, gotcha. I do have a set of step bits already I could use for the holes, at least. Glad I don't need a press!  They adjust to hold a range of taps. In your case you should be fine using just a drill on low range speed. There are some AU metalworking goons who can probably point you in the right place for a good tap deal. Maybe AliExpress?
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Jan 2, 2023 23:42
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Ethics_Gradient posted:Ah, gotcha. I do have a set of step bits already I could use for the holes, at least. Glad I don't need a press! What about this place? https://www.lprtoolmakers.com.au/metric-gun-nose-taps-hss-5-cobalt-sizes-5mm-to-12mm-aprica/ Or is that more expensive than you were looking for?
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Jan 2, 2023 23:53
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Yooper posted:Usually you use a tap handle for the square drive, like one of these. Ah that makes sense. I'll have a go at using the drill then, I reckon. I will have access to a workshop when school starts back up in a month (similarly could order on AliExpress), but was hoping to get it sooner rather than later as I've got this entire month off work and was hoping to get out and some more photos (more on that below). The cargo barrier is to make a more robust/permanent wall for the darkroom I'm building out in the back:  Actually... if there are any Aussies who want to make them for me and post them (I can buy the fasteners locally), I'd be happy to reimburse you. I actually take photos on metal as a hobby* if you'd prefer a Tasmanian landscape rather than cash. In the slim chance you're local, happy to come out and do a portrait of you, your workshop, etc, but I've got no plans to visit the mainland between now and when I leave unfortunately. A Proper Uppercut posted:What about this place? Yeah, 60 bucks plus postage for the two bits I'd need for this one job is a bit rich for me. If I knew whether I was coming back to Tasmania or not and had a place to store stuff for a few years I'd definitely invest in quality tools as I want to get more into metalworking in the future, but at this stage I'm not in a position to build up a library of quality stuff.
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Jan 3, 2023 00:04
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Ethics_Gradient posted:Dumb newbie question: those bits are fine, i got a few off banggood to try them out and was surprised how well they worked, i was using them in 2mm and 3mm wall steel box. i wouldnt expect them to last forever though.
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Jan 3, 2023 00:14
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echomadman posted:those bits are fine, i got a few off banggood to try them out and was surprised how well they worked, i was using them in 2mm and 3mm wall steel box. i wouldnt expect them to last forever though. You're probably right, as a machinist it just makes me recoil though. If it's just a few holes then yes I guess they would work.
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Jan 3, 2023 01:03
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Is that actually feasible, tapping threads that large into steel that thin? M8 is a thread pitch of 1.25 mm, so your fasteners get only 1 or 2 threads of engagement. I was always taught you want a bare minimum of 3x thread pitch deep, and even that's pushing it.
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Jan 3, 2023 01:14
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HolHorsejob posted:Is that actually feasible, tapping threads that large into steel that thin? M8 is a thread pitch of 1.25 mm, so your fasteners get only 1 or 2 threads of engagement. I was always taught you want a bare minimum of 3x thread pitch deep, and even that's pushing it. Oh, that's a really good point. The guy who put instructions on how he made his used those specifications, he says he patterned them after the manufacturer's ones because his barrier came with a couple. But when you think about it, you're totally right that it's not a lot of thread for the fasteners to grab onto. Maybe it's OK because it's the two of them together (separated by the thin bit of steel of the van's body)?
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Jan 3, 2023 01:22
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Ethics_Gradient posted:Oh, that's a really good point. The guy who put instructions on how he made his used those specifications, he says he patterned them after the manufacturer's ones because his barrier came with a couple. But when you think about it, you're totally right that it's not a lot of thread for the fasteners to grab onto. Maybe it's OK because it's the two of them together (separated by the thin bit of steel of the van's body)? You could look into these too : https://www.mcmaster.com/snap-in-nuts/
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Jan 3, 2023 01:24
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Yooper posted:You could look into these too : https://www.mcmaster.com/snap-in-nuts/ They don't seem to make them big enough, but I did come across rivnuts. It looks like you only need a bolt of the size of fastener you're going to use, some nuts/washers to act as spacers, and the rivnuts themselves (and a standard spanner to tighten it down). Any reason why this might not work on a body panel? The mounting holes are all at the part of the body where it has a separate internal layer, so don't have to worry about them poking out of the outside of the van.
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Jan 3, 2023 02:02
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Ethics_Gradient posted:They don't seem to make them big enough, but I did come across rivnuts. It looks like you only need a bolt of the size of fastener you're going to use, some nuts/washers to act as spacers, and the rivnuts themselves (and a standard spanner to tighten it down). Any reason why this might not work on a body panel? The mounting holes are all at the part of the body where it has a separate internal layer, so don't have to worry about them poking out of the outside of the van. That's a great option, I've used them before.
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Jan 3, 2023 02:32
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Yooper posted:That's a great option, I've used them before. Had a check, realised the main M10 bolt isn't going to work (to install the brackets, you drill out a 22mm hole in the body big enough for the backing plate to slide in behind the body panel), no way it'll fit in the existing holes. I could probably do a single 10mm rivnut in one of the smaller holes intended for M8 bolts, but I doubt that's very safe. I reckon I'll be fabricating the brackets in that case; had a look at someone else's Hiace with a cargo barrier today (just happened to be parked next to me at the beach, they were happy to let me have a look), theirs looked to be 6mm steel but also looked to be a homebrew job, PO probably found themselves in the exact situation I did, lol.
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Jan 4, 2023 08:27
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Feeling proud of myself right now because I made something really square today, for the first time. (No I was not taught how to properly make something square in machining school)
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Jan 6, 2023 18:51
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Dance Officer posted:Feeling proud of myself right now because I made something really square today, for the first time. (No I was not taught how to properly make something square in machining school) How did you make it square?
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Jan 6, 2023 18:59
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| # ? May 26, 2024 17:51 |
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It was an aluminium block that had one side facemilled to decent surface roughness (0.4 Ra or so), all the other sides were roughly sawed. I only needed 3 sides square in relation to each other. First step was to clamp the block down in jaws with the milled side face down, hammering it in place, and then facemilling it. Took it out, placed it back in the jaws with the newly machined side facing the unmoving jaw(not sure of the correct termninology in English), put a piece of ~Ø12mm copper bar between the block and the moving/loose jaw, then clamped it down again. Faced again, flipped the block 180°, put it back in the jaws with the bar, faced again. Checked squareness with the machinist square, barely saw anything.
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Jan 6, 2023 19:35
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