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Hello this seems to be the welding and fabrication thread? I have a couple questions for a welding project I'm doing. Working with square thin wall steel tube, I need to do some compound angle fitments and add some weld nuts, both are new to me. For the compound angle/compound miter stuff I'm not sure how to approach it, I have two ideas I haven't decided between: One is to use the cold saw in the shop, set one angle on the saw and do a sine plate or angled spacer to set the compound angle. This would control my angles and by flipping my bars right I think I could get all of my different pieces with the same angles done on the same setup. Not entirely sure how to control length, would probably lay out a cut with dykem and scribing and then eyeball to that for length and let the setup control angle. The other idea is to lay out all edge lengths with dykem, scribe the lines, then finish to length by hand on the belt sander. I did a test part this afternoon and the sanding will be time intensive but pretty easy, and with care during layout I can probably get close enough to my dimensions for it to work. Second question is around weld nuts. Googling around its all references to spot/pressure welding, I'd like to TIG as thats what I've got. It looks like I could buy https://www.mcmaster.com/90596A032/ and then drill a 3/8" pilot (or one letter bigger w/e), drop it in so the threads are inside the tube, then weld around the flange? Is this the right part and approach? All the references I can find are industrial spot/pressure welding or a random guy TIG welding a flange nut to the inside of the tube which I don't want to do. Flange thickness is the same as tube thickness so should be a easy weld. Any thoughts?
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Nov 16, 2021 03:40
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.065" wall, which is 16GA? I've got 4 uprights on the corners, so 8 cuts that are the same set of compound angles. I've then got 6 cross braces, 4 of which share the compound angle but not the primary angle, the other two are doing their own thing entirely. One lovely part is the shop with the saw is across town from the shop I have space to work in, so I think I'll take your advice and cold saw the rough cut primary angle and the sand/file/grind the compound in.
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Nov 16, 2021 21:01
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I'm also curious about rivnuts, I'm planning on using them for the smaller fasteners that'll take less load and so Id like to simplify things vs all weld nuts. Good to know about the good vs bad install tools wrt squareness of the nuts, I think I've got a good tool but will need to get new dies for my rivnut sizes. Seems like the main issue with rivnuts is them spinning out vs pullout or getting loose? I've seen you can get hex or half hex ones to improve torque, I'm planning on only using them for low torque mounting so hope to avoid any spinout. E: I was originally thinking I'd weld the frame and then add the weld and rivnuts but now thinking it makes more sense to add them when the bars are loose and I can do it flat on a table instead of in-situ. This is the way yeah? meowmeowmeowmeow fucked around with this message at 22:56 on Nov 17, 2021 |
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Nov 17, 2021 18:32
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For rivnuts? I'll be doing all my drilling on a Bridgeport with actual drills instead of a step drill so should be easy to get good clean holes where I want them. I'll do some trials for the weld nut pilot holes, the fillet they show between the flange and the tube makes it look like it needs a decently large pilot but I'd like to keep it as small as possible for good positioning. I'm gonna ask this in the CAD thread as well, but how do y'all indicate weldnuts on your drawings? I'm working in SW and usually do weldments as a multi-body part, and then add rivnuts and weldnuts etc in an assembly file. But I'd like to weld the nuts on before welding tubes together as they'll be easier to access and it bugs me a little to have my drawings separated like that. Any thoughts?
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Nov 19, 2021 18:35
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I was TIG welding some mild steel tube together last night and had a problem I've never had before, sudden large blowouts/holes in an otherwise stable weld. I'd be going along like normal running a bead and all of a sudden the arc would turn green like it picked up some contamination and a hole would start to form and suddenly run back along the bead like 1/2" without warning, no popping or spitting, just like the bead suddenly wicked back on itself and took a bunch of metal with it. Any ideas what I'm doing wrong? Tube was pretty clean and I didn't think I was contaminating my electrode but I was working in a different position/torch orientation than I usually do. This was on both butt joints and inside corner joints.
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Dec 16, 2021 19:03
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Tubes were all open, and this started happening halfway through the welding session so I don't think it was a gas issue, though I recently had problems with too much gas flow leading to random contamination and spitting. At this point I'm kind of thinking it was coolant from the cold saw that had dried in the tube or something, I couldn't fully wipe the inside of the tubes out so maybe thats it? It ended up being good hole filling practice though.
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Dec 16, 2021 21:47
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Thanks for the advice, checked the tank and it's a new fill from the gas store but no one else is running into this issue, it's a shared setup at the shop. I've been running mostly test coupons on smaller pieces of material and as I'm not worried about warping I've been just banging out welds without letting stuff cool, one of the guys at the shop said I might just be overheating the whole piece and eventually weird stuff happens when it all gets hot enough.
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Dec 20, 2021 19:11
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I'm putting a fair number of weld nuts into one side of rectangular tubing and it's causing it to bow pretty good, I'm letting each area cool before doing the next. Any ways to reduce bowing? All I can think of is clamping it to my welding table, but seems like the bow would just spring in after it's released? It's not a major issue, just wondering if there's a truck I'm missing.
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Dec 28, 2021 00:44
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Any advice on primers and paints for steel projects? Looking for a good etching primer and paint combo, open to spray or brush on. This is for a welded frame, don't really need it to be super pretty as long as it's durable and will prevent rust. Currently planning on a scotch pad in a sidewinder and then an acetone wipe down for prep, should I be doing more than that? I was looking at getting it powder coated but that's gonna be 600$ so I think I'll DIY it instead.
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Jan 13, 2022 18:28
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babyeatingpsychopath posted:Any of the green etching primers works fine. Acetone, then isopropyl, then acetone wipe and it's as clean and grease-free as you're likely to care about. Make sure you use dry and clean towels to get your scotchbrite dust off before you start wiping. Thanks for all this, but when I said spray I meant from a rattle can. I'll still use all your prep advice and go talk to the Sherwin Williams people and see if they have brush on options at I don't have a paint gun.
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Jan 17, 2022 16:53
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often times you can find smaller shops that are happy to do smaller work like that or specialize in it. Post a drawing of your part, small chance I'd be interested in making it for you.
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Jan 25, 2022 18:56
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I'd probably pass on that as I don't have a metric reamer, but a couple of thoughts: Bearing and shaft dimensions and tolerances are standardized and you should be able to get them from a book or online table, no need to roll your own or guess. You can look at ISO fit classes to decide how you want it to go together, then that fit plus the nominal dimension will give you your hope and shaft dimensions. If you filet the top of the keyway for the stepper shaft it will be millable, right now with the sharp corners it'd need to be broached and that's more $$$. I'd make the top of it a half round to make it simple, but the bigger the radius the cheaper that feature will be and shouldn't effect function of the key. If you can find a counterbore tool a couple thousands of an inch under your 5/8 bearing dimension you should be able to through drill the 1/2" hole, cbore to just under 5/8 (like 0.615ish) and then use a chucking reamer to get to your tightly controlled dimension.
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Jan 25, 2022 21:55
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Shame Boy posted:Oh of course that would exist It can be kinda hard to find recommended tolerances at times, machinery's handbook is a good but expensive reference, but a good bearing company should have an applications book with a lot of this info - same for a lot of mechanical components like o-rings, snap rings, motion components, etc. Usually a good place to start online and go from there. Yeah exactly, I haven't used one in a while as I usually do a circular interpolation on a mill vs cbore tool, but that's how I remember them working. Unrelated, is recommended amperage for aluminum TIG the 1A per thou like it is for steel? 35% EN, high freq for thin wall, acetone scrub after ss brush down, anything else to know? Jumping into the alumin deep end with some 1/16" 6063 angle I gotta stick together here soon, any advice appreciated. I've got a 1.5% lanthanated electrode and 1/16" 4043 filler.
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Jan 26, 2022 00:39
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thanks!
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Thanks for the advice and that app, pretty helpful. I'm just learning aluminum so also big amateur, watching lots of youtubes has helped. The 1A/.001" +~20% has been a good starting point, with balance and frequency helping a ton in getter a good bead. 60% balance and 180hz for my 1/16" practice but 75% bal and 120hz for 1/8" and 3/16" seems to be working so far but flip the settings and both welds look way worse. I feel like aluminum isn't that much harder to see and control the puddle, but figuring out all the settings is way more of a fucker than steel. Turn up the gas too much and the arc is all over the place, too low and it gets all oxide-y, etc. I'm still trying to get a handle on running high amps and moving fast to get good penetration without cooking the parts, its kinda stressful welding in a hurry but the couple times its gone well the beads look better, go deeper and my filler hand doesnt catch on fire.
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Jan 28, 2022 17:52
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There's usually a flat land at the base of the thread to allow for non-perfectly pointy threading tools and a matching relief on the major diameter to accommodate the increased minor diameter. Thread fits and gauging might be useful search terms, the info is for sure in machinery's handbook and might be in some of the other technical reference books - there's a poster that works for a company that puts out a free version, company and poster names escape me but thread dimensions might be in there.
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Feb 8, 2022 20:20
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Machinery's Handbook is expensive but its a pretty holistic reference book for all sorts of shop operations and mechanical design elements, I find its a useful reference and open it pretty regularly.
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Feb 8, 2022 21:27
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Can you.measure the thing that goes in the threads?
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Feb 11, 2022 20:55
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Bad Munki posted:Nope, it was missing when the post arrived, it's what I'm trying to replace. Yes, I could call up LMS and say "hi, I just bought a thousand dollar machine that can make pretty much anything, I'm missing a small rod that's threaded at both ends, help meeeeee" but frankly that'd be embarrassing given the circumstances. Why is it embarrassing to ask for all of the things you bought to be sent to you? If the threads on the part are still ok (I thought you were rethreading your toolpost beacuse they were messed up) you can try screws until one goes in and that should give you the diameter and pitch, or buy a pitch gauge and check. Minor diameter should be conclusively different between potential sizes, I assume you're stuck on pitch?
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Feb 11, 2022 21:43
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There's also a rotor cnc hobby thread that seems to have become the generic cnc thread. I've also had good luck with asking questions on the practical machinist forums but it's been a while since I've done that, not sure if it's changed.
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Feb 24, 2022 17:30
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ryanrs posted:Welding Tools (besides the welder) Adding to the good recommendations for clamps etc, I'd highly recommend a combination square and protractor set, some long steel rules, a big try square or square, dykem and a scribe, paint pens, and a good measuring tape. Having a variety of layout and marking tools is super helpful to have on hand so you can start from accurate measurements and clear layout when you build things. I also thing a slotted table made of tube is pretty useful, or a table top with holes for plug clamps, or a bunch of magnets if you want a flat welding table. Being able to clamp stuff to the middle of the table is pretty key. A welding table is a fun and simple project to make out of tube, either with a tube top for slots running the length or a laser cut sheet top for a smooth top or with holes for plug clamps.
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Mar 8, 2022 07:24
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Every time I have had to hand write gcode I've found it easier to use excel or python to generate my point list instead of trying to use variables and subroutines and macros on the controller. I find having easy to read as it runs gcode is really nice when proofing parts you wrote yourself instead of trying to figure out what a variable is and what it means for the move in the next block. It makes longer and less tidy code on the machine but it's much more usable n
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Mar 11, 2022 21:28
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welders on a cart are really bottom heavy though and that's what gives your bottle stability, if you do a freestanding thing please weigh it down so it doesn't topple. Also if your bottle is standing by itself, what is your welder doing?
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Mar 22, 2022 05:17
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I'm not an expert here but yeah I'd go with a36 and add ribs vs an expensive alloy. TBH you'll probably want ribs regardless, and if its almost good enough already they should get it over the line. If you stitch weld instead of continuous itll help with distortion and cracking and probably not make a big difference in terms of ultimate strength.wesleywillis posted:I figure this thread is the best place for it. Yeah you can increase the effective strength of a pin by increasing the number of places it would have to break for the two elements to separate. You've drawn whats called double shear, which means you have two shear zones on the pin, effectively doubling the area of the pin that sees stress when things are loaded. I've added green shear zones to your image, as well as shown an example of single shear:  Note that double shear also keeps in pin loaded in (approx) pure shear, where in single shear you can see how the whole thing would twist is its loaded, introducing a more complex load to everything. Also, small point of clarification: Materials will have a yield and ultimate shear stress, which is a force per area measurement, and then you use that and the loaded area of the part (in this case the cross section of the pin) to get the yield/ultimate shear strength of the pin. ryanrs posted:The widely accepted mechanical engineering authority, the McMaster-Carr Catalog says: Yeah its usually assumed that you are loading things in double shear when talking about failure load, but keep in mind that single shear strength is half or less than whats commonly in the book.
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May 27, 2022 06:15
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You can put a small chamfer on the end of the 8020 to clearance any internal radius on the bend. It's be cheaper to do bent imo if you're jobbing it out, might be cheaper to weld it yourself if your time doesn't have an associated cost.
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Jul 24, 2022 02:23
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Dumb question, what's the best corrosion resistant fastener option for bolting together aluminum in a wet environment? I'd go stainless but they'll galvanically corrode and black oxide steel doesn't cut it either. Is the move zinc plated steel or black oxided SS or???
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Oct 5, 2022 22:59
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Thanks y'all, plastic won't cut it strength wise so I'll look at some of the other options. Some are booted joints with nuts so I can run bonded sealing washers on both sides, but some are tapped holes in the aluminum so I'll look at those fancy fasteners. Where do y'all like to purchase your coated stainless options? Not seeing any of the fancy coatings on McMaster.CarForumPoster posted:You can also install a stainless fastener wet with primer. as in blast the fastener with primer and then screw it in?
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Oct 6, 2022 20:24
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Thanks. It's a fairly low corrosion environment, the structure occasionally gets sprayed down but it's enough to see the white staining of galvanic corrosion which is bugging me. I'm not seeing corrosion that's structurally concerning, just visual, so trying to find the right level of corrosion resistance without buying specialty fasteners or increasing costs too much.
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Oct 6, 2022 23:36
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yeah thats a loving steallllll
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Oct 15, 2022 20:21
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Not to distract you too much from fancy alloys because they are cool, but could you add ribs or something to your skid plate design to add rigidity and strength that way instead of going to expensive and hard to weld alloys that might require post-weld treatment to hit their properties? From what I've seen your designs are mostly flat plate, a couple of.ribs on the back side might do more for stiffness than fancy steel?
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Oct 20, 2022 02:14
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yeah thats what I'd do, triangle cut the tube, bend and weld your cuts.
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Nov 22, 2022 01:41
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I'm TIG welding a36 for the first time and getting lots of pitting and inclusions, more than I'm used to with other materials. Is this the name of the game with hot rolled or am I doing something wrong? I'm brushing with a SS brush, acetone wipe down, gas flow is fine (2x cup size, not acting like it's not got enough or too much gas). Not back-purging but I'm doing T-shaped joints out of flat with a fillet on each side of the vertical leg. The second side is a little worse and looks like I'm getting scale/oxide build up after it gets hot from the first weld, which I've seen before with CRS but not to this degree. Do I need to change my prep to include grinding or sanding off the millscale before welding?
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Dec 13, 2022 02:21
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Robots are a deep dark art I'm hardly familiar with, but I do know some things: RoboDK is a rhino plugin that can do offline programming for many robots, it's what we use for our cobots when we aren't teaching points manually. It's not the most powerful or tweakable compared to what I'm used to in CAM but it can get most things done. RobCAD is the industry standard for automotive automation and what our robot consultant used when we needed industrial robots vs cobots for a project. I spent a lot of time looking over the guys shoulder as he worked and it looks like a wild program, didn't seem very intuitive or easy to use. Most training is pretty heavily gatekept, I don't know if there are online resources unless you have access through the manufacturer or reseller. I was going to go to kukas training school but it was two weeks and I couldn't justify it, so I stick with our universal robots and their 2 day intro course. Large industrial robots are some of the scariest machines I've ever worked with and I would take safety incredibly seriously. Make sure to tape out the work envelope on the floor and strongly consider rigid guarding or a light curtain or radar based safety system. Cobots scare me marginally less but we still take safety seriously with them. Best of luck and if anyone knows more I'm also curious, I'd love to be more comfortable with robots.
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Jan 25, 2023 19:22
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Oof yeah, even just drilling 9mm at 175mm depth is almost 20xD which is gonna be tough. Is it a through hole? Does the whole thing need to be tapered? Drilling in steps to remove most of the material and then maybe a custom tapered reamer to clean up the remaining material and finish the taper might be the move if the whole thing needs to be tapered, but if you can redesign to limit the amount of taper needed that's probably the best bet.
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Feb 7, 2023 21:35
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It's gonna be so much harder to roll a sheet metal tube with no special tools than turn a 1"-ish OD round bar and drill a series of holes up the middle
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Feb 8, 2023 00:28
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I don't think you'll need a pilot hole on the lathe, with the drills in the tailstock they should do fine and will center on the cone left from the drill point of the previous one. I think a long pilot will be more likely to wander vs step drilling. Just make sure to peck drill with the occasional full retract to clear chips and you should be fine.
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Feb 9, 2023 06:10
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Idk if there was a watershed moment or just a critical mass of people who've had injuries prevented by ppe so it's more common to have mentors and coworkers who can tell you to wear PPE X as it saved their eye/hand etc. Also PPE has gotten less intrusive and more comfortable so wearing a respirator for 8h under a wedding mask isn't as terrible as it used to be. I also think better technology has made it easier to use tools in a safe manner - we got a new mill at work and between a 3d taster and one of those spinning windows there's zero reason to have the door open and the spindle turning more than 5-10rpm so we never felt the need to defeat the door safety vs old machines where the only way to get a good view sometimes is to run with the door half open. I think it's just lots of little things stacking up that have led to a culture shift vs any big moment.
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Mar 20, 2023 18:11
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Metal supermarket is great but 100% call your local place, their online system doesn't always show stock correctly and they'll usually check the drop room for you if you call.
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May 5, 2023 19:53
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it helps take up the slack between the gears so when it goes from feeding paper in to feeding it out theres no slack that could mess up the positioning of the pen on the paper. Prevents a little deadzone when the gear train changes direction basically.
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Jun 22, 2023 03:01
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There's these weird stripping pads I like, or rough scotchbrite pads, both on a grinder.
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Jul 20, 2023 03:36
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I'd second a jbweld/epoxy or shimming the area under the rivet head up to the right height, might be easier to work with than epoxy. Also if you aren't using clicos/skin pins they're super helpful as temporary fasteners and checking fitment before doing your permanent rivet.
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Aug 29, 2023 21:05
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