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Depends on how old the saws are. If they're really old (60s?) then it's going to be body-and-teeth made of some medium carbon "spring steel." Newer stuff is low-carbon (but not mild) steel with tool steel or carbide attached for the teeth. If it doesn't say "BI-METAL" on it then it MIGHT be all normal steel. Your best bet is to try to harden some and see how brittle it gets.
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May 11, 2023 18:42
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I found a big crack on the unloader valve of the pressure washer I am rebuilding. Tried to TIG braze it, but it just wouldn't work, the bronze just pooled on top and refused to wet in. Oxides on the part, cleaning didn't help. Gas brazing with flux would probably have done a better job. So I just upped the amps until it turned into welding. And then white smoke and white deposits burst out regularly from the metal. I got the main portion of the crack covered however, I can get the nut about as far back as it went before. I could see the sunlight through the crack so it was never gonna work without a repair. At least I didn't give myself zinc fever. I might have ruined it anyway however, there was a gasket inside it that melted because the elbow connector is screwed into a separate part that can rotate.   Of course last night I found a chunk of 32mm brass hex stock in my mailbox that someone donated for free. I am posting about this project on a local forum and apparently people appreciate it enough to donate stuff.
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May 12, 2023 04:43
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Making a new part, man brass likes to go everywhere, had to rig up some shields to contain the mess. Feel like I should vacuum this up into its own bag and save it for melting down.
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May 15, 2023 06:28
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By the way I ground a new tool for brass turning and it's working real ell. I used another tool with a top rake at first and it didn't work well at all, it was HSS, but a cheap grade without cobalt so it might have been partial reason. I bought a batch of NOS blanks with cobalt a while ago though so I ground a simple tool with no top rake and it worked great. I'm gonna have to grind a 55 degree threading tool as well, already have a 60 degree one. I grind these with no top rake either, because I see them as form tools. And no / neutral top rake means they won't have a tendency to dig in like I found happened with the carbide inserts, which mainly just caused me grief. If you got a worn screw or nut (or both) that can be an issue when threading I found.
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May 15, 2023 06:49
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My dad found a piece of round 2.5" brass bar stock one day at Boeing hardware and we turned it down to the diameter of a POG slammer, pretty sure that was the last time we used the metal lathe I recall it being covered in a fine coating of brass like that for the next decade After I dented like six kids POGs my brass slammer was banned at the playground by consensus
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May 15, 2023 07:55
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Free-machining brass is great, even on my puny lathe you can really take a big girl cut and make it rain golden swarf. On a more serious note: with brass I feel that carbide is more hassle than it's worth (at least what I've used, don't know about specific brass inserts from A-name brands), a sharp HSS bit will give a better surface finish so that's what I use. Just Winging It fucked around with this message at 14:43 on May 15, 2023 |
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May 15, 2023 14:35
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Follow up:Leperflesh posted:I'm struggling to find a mate for this screw. It is not a 12-24 screw. The thread pitch is different enough it won't go into a 12-24 nut. It's also not 12-20. I'm boned, gonna have to drill it out and tap for a different screw, disappointing but so it goes.
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May 15, 2023 17:03
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You can buy a thread gauge for ten bucks and figure out exactly what it is, assuming it isn't literally handmade somehow with a non-whole thread pitch. Or get a guy with a lathe to make it for you! I bet a lot of the goons in this thread would do it for free as a challenge if you mailed them the original.
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May 15, 2023 17:12
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As previously discussed, it's from the late 1800s so there's an excellent chance it's not any standard pitch that exists today. And yes, I know a guy with a lathe, but I'm not sure if it's worth an hour of his time to replace an old screw. If someone wants to do it as a challenge, I can mail you the other screw, but I do need it back!
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May 15, 2023 17:19
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I don't have fully arbitrary pitches available, but I do have an HLV tumbler and some change gear options, pretty good odds I can find it in there. Send it my way?
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May 15, 2023 17:50
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Just Winging It posted:Free-machining brass is great, even on my puny lathe you can really take a big girl cut and make it rain golden swarf. I've done some brass lathe work at school, both cnc and conventionally. Never had problems with getting dece finishes with carbide, especially on the cnc lathe.
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May 15, 2023 21:50
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It could very well have been a combo of my inexperience with carbide, and cheap inserts of unknown provenance.
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May 15, 2023 22:36
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His Divine Shadow posted:Making a new part, man brass likes to go everywhere, had to rig up some shields to contain the mess. Feel like I should vacuum this up into its own bag and save it for melting down. I've seen machinists run their lathe in reverse and flip over their cutting tool to 'downcut' brass in an effort to contain the mess.
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May 16, 2023 02:32
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Leperflesh posted:As previously discussed, it's from the late 1800s so there's an excellent chance it's not any standard pitch that exists today. And yes, I know a guy with a lathe, but I'm not sure if it's worth an hour of his time to replace an old screw. Considering the link to his YouTube channel you posted it seems right up his alley. Can't hurt to ask.
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May 16, 2023 02:52
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Dance Officer posted:I've done some brass lathe work at school, both cnc and conventionally. Never had problems with getting dece finishes with carbide, especially on the cnc lathe. Most inserts I have are positive rake so brass digs in easier. Nothing that says carbide cannot be used, you can find neutral rake inserts of carbide. Not sure if you can get both sharp and neutral from a shop however? I hone and sharpen carbide on a diamond wheel to extend or regrind inserts as well. I had to modify a drill last night for brass since it wasn't cutting well, I did what clickspring does here: https://www.youtube.com/watch?v=pAngKHIZgyA
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May 16, 2023 04:36
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You can get a good finish in brass with almost any tool. And once you get a the feeds and speeds set so that everything looks and measures good, it runs like that all day. It's the most forgiving material I've worked with.
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May 16, 2023 14:34
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I must be unique then. Drillbit didn't drill well and sounded bad until I modified it, I also had to grind the carbide insert of the boring bar to make it cut as it didn't want to engage even at first. Ground the top flat and sharpened up the front, then it was easy to bore to size.
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May 17, 2023 09:01
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Lathespin.gif posted:I don't have fully arbitrary pitches available, but I do have an HLV tumbler and some change gear options, pretty good odds I can find it in there. Send it my way? This kindly goon has volunteered, we're making arrangements via PMs! Thanks, Lathespin.gif! Your username instills confidence.
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May 18, 2023 03:53
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New part almost done, there's still the need to make an o-ring groove on the inside bore, I also managed to get .4mm thicker walls on this by being careful with the fitting of the spring that goes on the inside, a nice sliding fit instead of a sloppy one. Should make it stronger than the original.  
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May 18, 2023 11:53
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Leperflesh posted:I'm struggling to find a mate for this screw. It is a "slotted raised countersunk" steel machine screw from a tool (a folding drawknife) made approximately the mid 1890s (pat. 1891) in Boston by JS Cantello. I'm restoring an old tool and I'm well aware that perfect is often unattainable or stupid expensive, so closest match is acceptable... the previous owner just jammed a too-long wrong screw in to replace the lost or broken one and backed up with a square nut which is kinda cool but I'd rather have the right screw if I can find it. Leperflesh posted:This kindly goon has volunteered, we're making arrangements via PMs! Thanks, Lathespin.gif! Your username instills confidence. Hey so this mystery screw showed up yesterday, here's what I've got so far   It's steel, pretty soft (less than 40hrc), threads cut with a die. Fair amount of galling and wear on the shoulder. 60* threadform, main diameter at basically .249", pitch is... 24tpi, which I have on tap, sweet. Nice sized root, flanks are a lil rough but over .024" wires I get about .257"-.259". Looks like a vintage 1/4"-24 UNS to me!   The countersink angle looks pretty steep, by eye a fairly close match to a center drill so ~60*, maybe 70*? Drill a scrap slug to .257", mill off half a diameter and set compound to bore at 30* for a quickie gauge.   I guess 60* it is.  That's it for tonight. To do: -pick a threading tool and hone the tip radius to match the root, as the cutters I've found so far are either too sharp or too blunt -pull material, there's some 3/8" bar drops in 1045, O1 and maybe 4140 around here somewhere. Leaning 1045, I think? -find a ~.050" slitting saw & arbor for the screw slot, 1/4" 5C collet and block, etc. -do it e: found one more pic. So hey for anyone playing along at home, you can gauge thread pitch directly with whatever known fasteners or taps you have handy, just ignore the diameters and mesh them with a backlight and take a peek. Here's a 1/2"-20 tap with a 1/4"-20 screw, for example: 
Lathespin.gif fucked around with this message at 10:29 on Jun 1, 2023 |
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Jun 1, 2023 10:13
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Yay 
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Jun 1, 2023 16:48
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god drat well my confidence is soaring, even as I worry at how much work I've given you lol I think if you have a choice of materials I'd prefer harder over softer, but 1045 is hardenable carbon steel and will probably match better than stainless, O2 is overkill. The screw slot doesn't have to be precisely .050 if you can't easily lay hands on a saw of that width, a little wider or narrower is OK. It's cool that it really is 24 TPI, I wasn't too confident that I'd measured right but I got it and that's nice 
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Jun 1, 2023 17:03
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Making that half-milled gauge is such a pro move, I’m totally stealing that idea.
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Jun 1, 2023 17:14
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Thread title delivers
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Jun 1, 2023 20:45
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Leperflesh posted:
Yeah I have some stainless bar too, but I figured it wouldn't match character with a vintage tool as well as carbon or alloy? Some options I dug thru:  For stainless we have 304 (but too shiny), 15-5 and 17-4 (both probably a nice fit, but again too shiny). For steels I'm pretty sure this 4140 is annealed, if it was prehard it'd probably be the one. O1 would be good, even if overkill. Decided to roll with the 1045, the grade 8 bolts would be a solid choice too but more work to prep. I thought I maybe had one lil' piece of 1144 lurking in a drawer, but no luck today. Threading tool is prepped, tip radius stoned just smaller than the sample. I should really make up a phone mount for my scope, this handheld focal length thing sucks   Running the spindle in reverse and cutting on the backside, so I have easy compound clearance to the chuck for the taper. Using a cheapo ccgt for aluminum, they leave a nice finish in harder stuff if you're gentle with them.  Didn't feel like trying for a disappearing thread today and angering Crom with my hubris, so a .050" thread relief groove to minor diameter it is. Stone a radius on the tool corners to help keep the stress riser ghosts away.  Blue it up, sanity check for alignment  Looks good, dial for 24tpi and take a scratch pass, confirm pitch  Solid, take 1-3 thou passes with the compound until it starts to look like a thread, once it gauges about .256" the threadform is done. Surf a tiny triangle file through it under power, break them sharp crests, wire brush etc.  Part off, switch to 1/4" collet and face to length, chamfer the corner heavy and start filing in the dome     Almost done now, just needs a slot. Mill time.  A reground .051"? That'll do.  Touch off top of screw, down 1/2 of .048" blade + 1/2 of the ~.372" screw head diameter to set Z, touch off the cut and feed in ~.070". Was gonna do .050" but it looked like it wanted a bit more, idk?  A quick deburr under the scope and a final spin with some 800 grit for the head, and that's all folks!  So it's still in the white and just wetted down with some WD40 for now so it won't flash rust, but it does have those 45 points of carbon- I could give it a torch ride and an oil dip, see about hardening it up a bit and tempering it back? Or just mail it out as-is and you can do whatever finishing you're into or just run it, it's all good.
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Jun 2, 2023 08:40
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Goons are the best.
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Jun 2, 2023 14:01
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Kaiser Schnitzel posted:Goons are the best. Yeah, this has been so rad to be a fly on the wall for.
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Jun 2, 2023 17:20
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One of the most beautiful things I've seen done, and I have an absolute master machinist at work who makes me all kinds of bespoke tooling off my back-of-napkin drawings. loving bravo.
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Jun 3, 2023 03:01
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i feel like i contributed in a tiny way by first suggesting that some goon in this thread might be able to make the screw for fun. A+ work, wiring the threads and stoning the tool to get exactly the right profile, just stellar overkill
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Jun 3, 2023 06:06
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Holy poo poo yeah that's amazing! I can do a heat quench and temper here if I feel that's necessary, I've got a bit of MAPP left and also an oxyacetylene rig, and a retired toaster oven that'll do 550F for the temper. But I'm like, 90% sure that's not necessary. Thank you! I'll be sure to post follow up photos of the rest of the restoration. It's a woodworking tool so I've mostly been posting about my restoration projects over there, but obviously you guys deserve to see how this goes too. Also I bet if you made ten more of those you could sell them on ebay for five bucks each to other people restoring these specific 1890s drawknifes. I'm sure that'd totally pay you back for your labor, right?
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Jun 3, 2023 22:28
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Breaking Taps built a tiny horizontal shaper that feeds 0.0000025 IPM to get stop motion footage of chip formation from a SEM and it is some astounding footage https://youtu.be/aF7ltBT_atA
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Jun 6, 2023 01:56
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I got screwed! Lathespin.gif made TWO OF THEM goddamn These are the handles of the JS Cantelo (patent 1891) folding drawknife (click for a complete, assembled example) I'm working on. As you can see, the one on the right is in progress, I've been working over the metal with scotchbrite and wire wheel etc., haven't gotten to the wood yet.  Here's how the original screw that I sent lathespin.gif fits   Here's the makeshift replacement bolt and nut that a previous owner used to replace the missing screw:   You can see in this second pic how the threaded section acting as the "axle" or pin of the part got damaged over time. Here's the replacement, one of the new, and the original screw look, side by side  And here's fitment of the new screw:    It's a perfect fit. Threads in with no trouble, snugs down very nicely. You can see there's a bit of that chamfer or relief showing inside the slot, but I don't think that's going to be a problem, there's plenty of surface for the center piece (the blade) to make snug contact with the unthreaded shank of the screw. You can see the blade section in this pic I took a couple days ago, on the right. I definitely didn't have to slice my finger open before bothering to make the edge safe with some tape and cardboard.  I need to reproduce this brass spring, it only had one. I tried using some of the steel wire I have lying around but none of it is springy enough, it just deforms.  I have found sources for brass spring wire, e.g. https://www.fortepiano.com/index.php/products-menu-item/wire-menu-item/copper-alloy-menu-item/spring-brass-menu-item but I haven't gotten around to measuring the original spring's wire to see what thickness I should get. I'll post as I get this tool cleaned up and ready for use. lathespin.gif declined to be paid for their work: quote:Don't worry about it, toss a couple bucks to your local critter shelter or RAINN instead, if this all works out! I foster cats in collaboration with our local cat rescue org, Community Concern for Cats, so I decided to throw cash at RAINN. $50 plus transaction fees to RAINN and I'd encourage everyone who found lathespin.gif's work to be valuable to make a donation to a critter shelter or RAINN if you can.  Thanks lathespin, you're awesome, these screws are great, this thread is great, I love somethingawful.com.
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Jun 10, 2023 04:03
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Jun 10, 2023 15:36
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 The first part gives you all the zeroes you need for diameters and shoulders and such, best to flip it and make a spare before you break setup, especially when you need to swivel the compound around. Goobering up a thread pass and scrapping a part sucks, but needing to first switch setup to go back and cut another blank is basically the worst. Plus in this case it's an odd-duck size and maybe has two handles, I figured an extra is good! Length looks pretty solid from here, could have made the threads maybe half a turn shorter but need to bottom out on the head before running out of threads, and I wasn't sure if they'd seat any differently in the taper. Looks like ~2/3 of the shoulder will engage so yeah should be good! Overall I think I made them a couple whiskers longer, I figured you can always file or grind them shorter to match when fitting if needed. Mcmaster and MSC do still have 1/4"-24 taps and dies available, in case you need those or someone else wants to go into business here! What a sweet tool, wow. A lot of nicked fingers and shavings in there. I love those handles, talk about character! Are you restoring this to put it to work? Also you shoulda mentioned spring wire earlier, I'd have tossed in a couple lengths!   Brass is an odd alloy choice for a spring, I'd def. recommend phosphor bronze instead if you don't want to use steel or stainless wire.
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Jun 10, 2023 18:56
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Leperflesh posted:I foster cats in collaboration with our local cat rescue org, Community Concern for Cats, so I decided to throw cash at RAINN. holy poo poo yr redacted info  man I really needed that today, thanks! I'll pass it on, hell yeah  
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Jun 10, 2023 19:47
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Ahhhh, OK so I wondered if you'd gone back to start over to get a second one but it makes way more sense that you just cut two parts as you went along. It is a very cool tool and yes it's for use, not to just hang on a wall, although I do already have another drawknife I've restored and a third in the queue... but I also know a guy who needs a drawknife so one of them will go to him. I restore tools to a working condition, I'm not worried too much about getting them "perfect," and usually I can just improvise a missing part, but this one screw really threw me. Lathespin.gif posted:Also you shoulda mentioned spring wire earlier, I'd have tossed in a couple lengths! I mean I don't know what it is, it's definitely brass or bronze colored and it's springy but it could be phosphor bronze! The spring is hidden and just needs to function but I figured if I use the same material it'll probably have the right uh, springiness, or close to it. It holds the sort of tube cup thing onto the steel ear, you pull the tube back to re-orient the handle and then the spring presses it back on. So it only has to be strong enough, but it could be a bit stronger and still work OK as long as it's not ridiculously hard to retract the tube. It does have a fairly tight tolerance, it juuust fits into that tube and then it just fits over the round part of the handle, so the spring wire can't be much thicker than the original. Hence why I want to measure it, still haven't gotten around to that yet because today we were painting the house and I am teaching myself about stucco repair. Also thanks for donating to CC4C! Your money literally saves the lives of cats, gets ferals and strays off the street, fixed, and adopted. I really appreciate it. e. the spring wire is around .045 to .048" (1.143 to 1.122 mm) so I would guess probably anything from .04 to .05" wire would work fine. Uh... of course, that's 18 gauge. 0.048" (1.2mm) e2. holy poo poo thespringstore.com is cool, you can browse their catalog etc. but they also have a spring generator where you put in your measurements and material and it creates a blueprint for you and you can get it emailed and a quote and it calculates all the spring specifications, gosh  Leperflesh fucked around with this message at 07:12 on Jun 11, 2023 |
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Jun 11, 2023 06:07
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Switched to straight Co2 on my MIG welder this week. So far I don't think it's bad, it splatters more, feels rougher. But I find it easier to weld with on sheet metal, seems less prone to blowing holes IMO. Based on how bad a rep Co2 has I thought it would be barely usable. Just goes to show you can't always just go by what you read on message boards.
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Jun 14, 2023 11:02
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Does anyone know what specific abrasive is used in blue polishing compound (so-called "blue rouge," which is a term that drives me nuts) that is used for plastics? I know that the black stuff is emery grit, brown is silica, white is aluminum oxide, red is iron oxide, and supposedly green is chromium oxide but I've never used that one. But I can't find anything about what is in the blue bar.
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Jun 18, 2023 04:23
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Sagebrush posted:Does anyone know what specific abrasive is used in blue polishing compound (so-called "blue rouge," which is a term that drives me nuts) that is used for plastics?  I'm seeing basically this in various SDS's, or just aluminum oxide. We order grinding wheels that are aluminum oxide and the same grade and grit will be different colors depending on the manufacturer with no impact on performance.
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Jun 18, 2023 12:28
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Does anyone in this thread know anything about cad/cam and cnc machining in orthopedics? Having finished machinist school recently I've started to think about how I want to develop professionally and what I'd like to end up doing. I like machining but I'd like to focus a bit more on helping and interacting with people, and I'd like to end up doing complex and challenging machining work.
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Jun 18, 2023 13:27
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