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I wanted to do something nice for my girlfriend, so I was thinking about taking some worn silver coins and making a silver casting out of them. I have some refractory cement lying around and I wanted some advice whether this would work as an investment casting. I was thinking I could use a small stainless or mild steel cup that I make and a mapp gas or propane torch to melt the silver and then pour it into a mold. I have plenty of refractory cement here to make several small casting so I was thinking I could make a lost wax casting or lost foam casting. Perhaps cutting something out of foam and then using a solvent to dissolve it out or maxing it out of wax and using the torch to burn out the wax.  BTW this is not the design I would use.
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May 18, 2010 05:16
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I am a prototype CNC machinist and have done a bit of CNC repair work if people have questions. I do programming, with mastercam X4, setup, etc.
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May 2, 2011 08:49
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JB weld? Also machine the rod ends and claim theyre racing rods.
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May 7, 2011 02:48
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What is a jester mini ill and why is angle iron involved in its construction?
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May 9, 2011 06:44
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I'll never understand why people will spend a grand building one of these but not $1000-2000 to resurrect a 1980s VMC or knee mill and end up with a real machine rather than a toy.
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May 10, 2011 03:56
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I can spot the print made by someone who doesn't know what a datum or centerline is or how to dimension or tolerance anything. Also lol chain dimensioning. EDIT: Is it the radius and length call out on the right hand side? EDIT2: Never mind called out as 3.0". What is it? Lord Gaga fucked around with this message at 12:56 on May 10, 2011 |
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May 10, 2011 12:05
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Nerobro posted:1) My knee jerk response is to call you an idiot. 1) Good way to start a post. I definitely want to hear what you have to say. I do this professionally, am half way through an engineering degree and have repaired two completely non functional CNC machines to date. One was just fuses and servo brushes the other a bad VFD, some fuses, and some misc stuff. The result was a working early 80s CNC lathe and working early 80s VMC. 2) As far as invested time, I don't think either would definitely be faster. 3) I bought a Hurco KMB-1 that powered on for $500 + moving costs. From a dealer though you are right. Still this had servos and the ability to drip feed. Not a VMC but a very versatile machine. 4)According to the link you posted under "The Brute" "This mill will cut PVC, Plexiglas, Wax and wood at speed up to 12 inches per minute. With 1/16" milling bits it can also mill Brass and Aluminum but at much lower speeds. The machine can support a 6" by 6" Deck. The actual milling area is 5-3/4" by 5-3/4". The Z axis has a 2-1/2" range." ... "Homemade Delrin blocks ride on the aluminum channel. They can be adjusted for zero play. The machine will cut parts better than .003 if you build and adjust it correctly. " ... "This machime is built using aluminum window channel, PVC, Delrin and other easy to obtain materials. I made most of the parts with simple handtools. I also used a scrollsaw, drill press, belt sander to make some of the parts. " i.e. a toy. Those are toy machine speeds, toy working area, toy machinable materials, toy accuracy and toy construction. "My brute can take a 1/2" deep, by 3/4" wide pass in aluminum. That's nothing to laugh at." It is when it is at 1IPM and all it does is wear away at your tool because you're going .0002 per tooth. If yours is way better ok but the link you posted screams toy. Can you make a 4 cyl header flange with it? A sherline is also a toy. These are very very cool toys, but toys none the less. They are not professional machines and they have far less profit potential than a real machine. Even a tired old mill with encoders that are off .0005 and are a bit worn will do way better in all categories mentioned. That said, yes it is probably the best you can do for $400 and is still a very coll project. I'd take an old professional grade machine any day though because I know it can make whatever I want it to out of any material...when it decides to turn on.
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May 12, 2011 06:35
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Nerobro posted:I had a long thing to post here. But i'm going to sum it up, you called my mill a toy, based on a long string of assumptions. And now you're trying to pull the "I do this for a living" bull. Yes many people do not have the space. I feel a little annoyed at some oft he replies because, again, I do this professionally. I am a prototype machinist at an engineering R&D with about half a BSME. I also have a machine shop in my garage currently equipped with a 13x40 lathe and bridgeport manual mill with a DRO and one of these days I will get around to a cheap quill DRO mount. So I do this as a hobby as well. Linux assassin- we are talking about mills. I am not confusing anything. Your post doesnt even really make sense because the vast majority of hobby cnc machines are mills. While that might change with the popularity of repraps and maybe an increased interests in lathes, AFAIK most home CNC machines are CNC mills and Neoboro is exclusively talking about making mills. Also when we talk about knee mills, we are not referring to manual mills or retrofitting them. We are referring to CNC knee mills like the bridgeport boss or my old Hurco KMB-1 as opposed to VMCs. Also many do not need a full controller retrofit because they can accept behind the tape readers. E.G. The Hurcos of that era. I bought my bridgeport, Hurco and Knee mill for $500 each + moving expenses and, of course, tooling. Neoboro- I run most of my 1/4" cutters at 250-300SFM and about .003/tooth in aluminum with uncoated carbide. You're the one both calling people idiots and making huge assumptions now. I had no way of knowing yours was so much better if it is, in fact, so much better. How about a contest? I would love to see your mill interpolate a 2.5" hole by clearing all the material in 1/2" thick 6061 aluminum with a 1/2" end mill in under 5 minutes. This is something that most entry level machines in the 80s could accomplish in about 90 seconds. Wood and plastic yes a toy mill or a router is fine, but when you get to aluminum, to actually do things productively with it and not chew up cutters or your piece due to vibration you start needing some heftier equipment or some decent damping system. It should be round within .002 TIR, have a decently smooth, chatter free finish (no more than 125RMS) and have no more than .0002 taper across the face. Again this is easily doable in even a worn CNC mill in far less time. Also your craftsman SK analogy is false because they both can accomplish the same thing. Were not talking brands here we are talking a drill press versus a hand crank drill.
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May 13, 2011 02:37
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Working in trades is just barely a step up in terms of working retail in terms of the percentage of managers and bosses who are uppity self important dicks. I have been very lucky for the most part but man do I hear stories like yours. I think its worse the more "blue collar" the image that goes along with the job. Also the mill I would be doing this on is a fairly entry level taiwanese mill. Ill see if I can find anything about its specs but the table is fairly small as professional machines go, it doesn't have a ton of travel 20-something atc pockets etc. etc. Id liken it to a early 90s version of a Hurco VM1. Also 2.5" ID hole. EDIT: Actually I think this is it: http://www.go-dove.com/event-11985/Machine-Tools-Liquidation-Center/lot-5/Excel-PMC-5T18-Excel-PMC-5T18-Vertical-Machining-Center Long story short, 40 taper, less than 10HP. Also hilariously bad Chinese collets though I will probably use an endmill holder. The collets are such cheap pieces of poo poo that theyre labeled 2/1 for 1/2" collets. I am not joking at all. Lord Gaga fucked around with this message at 07:36 on May 13, 2011 |
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May 13, 2011 07:31
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For carbide endmills check out http://www.lakeshorecarbide.com/ They're pretty highly recommended on practical machinist. I have only run one of their endmills but with good results.
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May 13, 2011 23:54
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EL headers can be roughly EL. Industrial machine shops do industrial machining. Automotive machine shops do automotive machining. They dont really mix. Further more some shops may only do certain engines or certain transmission bellhousings. Do not try to machine your own head studs. There isn't cheap engine machining. A block has to go on both a mill and a honing machine and has to have fixtures for each type of block many times.
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May 20, 2011 06:13
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The Scientist posted:It may just be because I just watched Mad Max and then The Road Warrior again for the hundredth time, but did you consider making a triple motorcycle? Heat Treatment Specifications: * MIL-H-6088 - Heat Treatment of Aluminum Alloys * AMS-H-6088 - Heat Treatment of Aluminum Alloys * AMS-2770 - Heat Treatment of Aluminum Alloys * AMS-2772 - Heat Treatment of Aluminum Alloys * AMS-2750 - Pyrometry * ARP-1962 - Certification of Heat Treat Personnel * MIL-STD-1537 - Electrical Conductivity Test for Verification of Heat Treatment of Aluminum Alloys * AMS-2658 - Hardness and Conductivity Inspection of Wrought Aluminum Alloy Parts And some more: MIL-H-6875, MIL-S-6090, MIL-H-7199, MIL-B-7883, MIL-S-890, MIL-S-12515, MIL-I-45208A, MTI 2000 Not sure which are for steel. If you sp[ecify one of those standards though theyll know what you want. Though speccing one of those may be too much. That said youll probably not get them heat treated when you find out the cost of what you just asked.
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May 22, 2011 01:11
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oxbrain posted:The scale is just mind bogglingly tiny. Tolerance on those is +/-.0002" on size, parallelism, and squareness. That's 5 microns, roughly the diameter of a red blood cell. In theory, the more sensitive areas of skin(lips, tongue) can detect grit down to 3 microns. Your hands are only good to 20-30. You can imagine the difficulty in keeping everything clean. Don't hold it in an air conditioned room for too long or you'll be out of size tolerance. I had to machine some jaws to make this in a lathe and got my first real noticeable experience with work hardening. Ill take pictures of the jaws but basically they were only half machined so that the back could be used as a stop and I went to bore them straight through taking .050" DOC passes with a long boring bar with a coated big nose radius triangle insert. It took probably 8 passes to get to my larger outer bore and then one cleanup pass straight through. The jaws are made of unknown decently hard steel. well the part that was previously machined cut smooth as butter at 1200RPM, 2" ID and .050 DOC but the part that had those previous 8 or so passes chattered as soon as it reached it. I was simply amazed at the difference it could make. I still can't quite wrap my head as to what make the steel work harden like that. 
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Jun 3, 2011 05:03
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Why conventional mill on the finish?
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Jun 3, 2011 05:22
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If its normal stock and it is unfinished (straight from the mill) it'll have it printed on it. Examples are 304, 303, 316, 440, etc.
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Jun 9, 2011 16:59
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If anyone here wanted to try their hand a jewelry making, here is your chance to do so cheaply... ...alternatively, diamond encrusted knife blade. http://forums.somethingawful.com/showthread.php?threadid=3421608
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Jun 27, 2011 18:22
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As far as welds being convex on a fender like that....shouldn't they be? Its not like youre gonna be able to blend the weld with the surrounding metal nearly as well as you could a little bondo. EDIT 1: Also as far as case hardening goes. Why case harden a knife? You could just as easily get a tool steel drop that can be made almost file hard. I would imagine that your knives aren't getting worn on so much that case hardening would be useful more than "hey I did this to this knife." EDIT 2: A2 has a maximum hardness comparable with a shallow "file hard" case hardening. I.E. >58 Rc Lord Gaga fucked around with this message at 05:09 on Jul 1, 2011 |
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Jul 1, 2011 04:59
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I see tool steel drops at my local metal supplier for like $2-3/lb IIRC and they're usually labeled as to what alloy.
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Jul 3, 2011 23:03
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Generally for automotive stuff, the best thing to learn is MIG welding. This is because of the weird angles, tight spaces and general inability to clamp things together often times. When you have a torch with a tungsten in one hand and the filler rod in the other you are out of hands to simply hold the pipe up there. That said I have built a custom chopper as part of a team and we exclusively used tig welding so for motorcycles its not really a big of a deal. On cars its a pain to take stuff out for repairs, on a motorcycle much less so. Get some 1/8" and 1/4" aluminum and steel plates and work your way down thinner from there. You'll be welding nicely in no time. It is a fairly cheap hobby once you get started. I taught myself to weld with this Chinese TIG welder and I have been thinking over selling it as I haven't welded anything in 6+ months. Id want $500 + shipping PM me if interested. http://cgi.ebay.com/TIG-Arc-MMA-AC-DC-Welder-Aluminum-NEW-WSME-200-2-1-/110696519777#vi-content
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Aug 2, 2011 17:22
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COupon via google http://images.harborfreight.com/hftweb/campaigns/localmedia/general_july/images/22.jpg?hftref=cj
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Aug 12, 2011 20:35
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Chauncey posted:Hi all, Really really great work.
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Aug 15, 2011 19:54
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I saw the drill bit that makes a square hole quite a while ago on the british show QI and these youtube videos cropped up on practical machinist. They're pretty expensive and theres a fairly limited application for them. If youre buying just the bit you'll need a special holder that describes the rounded square required to make it drill a square hole. It's center line has to move around to make the square.
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Oct 16, 2011 08:23
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Brekelefuw posted:I probably asked here a while back, but can anyone recommend any Lathe and Milling books? This was my machining text book and it is quite good and rich in pictures. It is quite basic and will get you far enough along to know whats out there and what stuffs used for and how to use it. It is fairly light on modern CNC instruction. If that bbook is too pricey consider an older edition, it really is quite good for a beginner.
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Oct 25, 2011 07:33
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Brekelefuw posted:You never gave the title! Heh, http://www.amazon.com/Machining-Fundamentals-John-R-Walker/dp/1590702492
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Oct 25, 2011 18:47
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Apocadall posted:So I've started learning how to weld in my Dad's auto-body shop and I've been using a MIG(?) I think. It doesn't use gas though, it's a wire feed and grounds to the metal you're welding to melt the wire. What kind of machine is this? I feel like I'd be able to do a much cleaner job if I was using gas and a separate wire. MIG minus the gas is generally called a wire feed welder.
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Nov 3, 2011 20:46
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Lets Play Arson posted:You could try something like this. Plus the suggestion of using lumps of modelling clay to make finger dimples so you can actually get the things out. Thank you for this.
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Dec 1, 2011 23:32
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Good, then we few machinists can finally talk about machining which is way cooler anyway.
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Jan 4, 2012 08:18
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This was my machining class textbook. It is simple to understand with tons of pictures and drawings. http://www.allbookstores.com/book/compare/1590702492
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Jan 11, 2012 19:44
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Get three piece of angle iron, weld them together like so:
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Jan 15, 2012 01:05
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Blacksmithing is testicals
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Jan 22, 2012 19:01
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duck hunt posted:I've wanted to try this as well, but I was going to take some small diameter pipe and cut it down and polish it. I guess that is the low effort method. Turning on a lathe if were talking about symmetrical, stainless rings. Otherwise, centrifugal casting.
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Feb 9, 2012 13:56
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For flat tig on MS that is pretty ugly to be honest. Its not very straight, the beads are inconsistent in size and spacing, and it looks like your heat mightve fluctuated quite a bit as the welds start out flat/almost concave and end up in a somewhat convex glob. For practice, scribe a line on some flat metal and try to follow it the best you can. Try to keep the same speed and just slowly dip.....dip.....dip..... Whats up with the metal there? Is that rusting through? Are those globules of weld bead on a crack in the subframe? Those look especially bad though I am not sure if thats a crack or if those are just practice or what.
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Feb 17, 2012 08:36
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hailthefish posted:Looks like a globby weld that didn't get the slag cleaned off yet or.. spray paint.. or something. This is TIG, there is no slag
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Feb 17, 2012 16:15
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waffleking posted:I was running about 50 rpm right there, my feed rate was fairly slow. The dial on the feed is not legible but I'm gonna guess approximately I was going around 1.5-2 IPM. I was having trouble burning through my inserts going any deeper, any tips on how slow I should be going to get bigger cuts? I'm still green to all this and like to learn all I can. They need to be flat from the mill, but they are called out with fractional dimensions so it's a loose tolerance. I was using a two piece vise on the first one yesterday and had a hell of time getting it to stay still. I welded some bars on the side of this plat and clamped it down to the table and cut about two hours off my time and got a way better finish. Assumptions: Coated Carbide 8", 10 tooth indexable face mill 50 Taper Machine Good Workholding 100% Axial cut Id run about 150SFM (72 RPM) and .0025/tooth (1.79IPM) @ .030 or deeper if material can take it and not deform. I know this isnt CNC but if youre doing a bunch of them it is not that hard to measure feedrates using a digital caliper and stop watch.
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Feb 23, 2012 15:30
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Bad Munki posted:Yeah, sorry, 1/4" plate. I don't really wanna buy a billion dollar bit for these three holes I need to cut, though :P CNC mill with a 1/4" or 3/8" two flute. Constant tool engagement starting in the middle and spiraling out. You'll need a cam program to do that. If you can use Fanuc posts then I can help you. This is the fastest way to remove the material and leave a nice finish.
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Feb 24, 2012 03:20
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Titanium is considerably more difficult to machine than SS. You might maybe be able to go to a welding supply store and buy a 1/4 lb of 1/8" titanium filler rod. Expect that to be around $25 as well.
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Mar 1, 2012 05:42
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The reason most grills are mild steel is cost, not other reasons. Mild steel costs about 1/6th as much.
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Mar 2, 2012 01:16
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duck hunt posted:Also starting with the right sized hole. If the hole is too small, it requires a lot of force, which means it is going to be a lot harder to hold in level on both the x and y-axis. This is really bad advice and just down right incorrect. A 10-24 tap drill size is .1495 and the tap is larger than that. Youre probably thinking of a 6-32 which is also very common. I know from tapping them so much that 1/8 is on the larger size of tapping a 6-32 and is the size I would use for a forming tap. For a cut tap I would use a #36 drill which is .1065 in aluminum, larger for stainless steel, but still not a 1/8 unless I am forming the threads. Pick the recommended tap drill size based on the type of tap (forming vs cutting), using a tap drill chart (google this), and to the corresponding thread depth you want. (Given in a percentage, e.g. 70% thread.) Use a bigger hole for more difficult to machine materials if you want to save yourself headaches. If you're CNC tapping a forming tap is pretty much always the way to go. I really like forming taps for aluminum as well.
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Mar 14, 2012 07:57
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oxbrain posted:We have to make everything to print, but sometimes we get it changed after explaining that it'll take another couple days if they really want that tolerance.  I have never met a machinist on salary.
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Mar 16, 2012 20:05
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| # ¿ Apr 24, 2024 03:54 |
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In my experience 85+% of welders couldn't give a gently caress what tolerance you put on anything if its less than a 1/16th. If something needs to be precise I always machine it after welding and try to leave some for making stuff flat and perpendicular.
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Mar 17, 2012 19:55
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