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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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#1
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How about a welder for edm power source?
I broke a 4-40 tap in my filing machine casting. It was for the top
cap, which is there to hold packing as a seal for the file rod, so not that big of a deal since there are five good screws. But it feels like a berry seed in my tooth. Aggravating. I got Langlois' book on building a hobbyist edm, but have a few other thoughts. I have a very nice tig welder, Miller Dynasty 200DX. In tig mode, it'll go down to 1A DC or 5A AC, plus a pulser on dc up to 250 Hz and lots of control over ac frequency and wave form. Seems I might be able to use it in lift start mode for edm. I'd still need to build the carriage, stepper drive, controls, etc. I have a Beaglebone Black which could be applied to that job. I can get a reasonable stepper for $11 from the salvage place in town, plus some linear bearings and a bellows coupler for not much. Any known reasons the welder is a bad idea? Thanks. Pete Keillor |
#2
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How about a welder for edm power source?
Pete Keillor fired this volley in
: Any known reasons the welder is a bad idea? Thanks. Pete Keillor No... but why not just 'urge' the thing out mechanically (punch, core drill, magnets, etc), then if the hole is messed up, weld the hole full, and then re-drill and tap? It would sure take less time than building new machines for a 1-hole job! Of course, if you really WANT an EDM around, go for it. Lloyd |
#3
Posted to rec.crafts.metalworking
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How about a welder for edm power source?
On Sat, 15 Aug 2015 17:00:52 -0500, Pete Keillor
wrote: I broke a 4-40 tap in my filing machine casting. It was for the top cap, which is there to hold packing as a seal for the file rod, so not that big of a deal since there are five good screws. But it feels like a berry seed in my tooth. Aggravating. I got Langlois' book on building a hobbyist edm, but have a few other thoughts. I have a very nice tig welder, Miller Dynasty 200DX. In tig mode, it'll go down to 1A DC or 5A AC, plus a pulser on dc up to 250 Hz and lots of control over ac frequency and wave form. Seems I might be able to use it in lift start mode for edm. I'd still need to build the carriage, stepper drive, controls, etc. I have a Beaglebone Black which could be applied to that job. I can get a reasonable stepper for $11 from the salvage place in town, plus some linear bearings and a bellows coupler for not much. Any known reasons the welder is a bad idea? Thanks. Pete Keillor It's an interesting idea. Basic EDMs deliver current from a big capacitor, however, so the energy in that spark is a lot greater than you think. We had a tap buster (a proto-EDM) in my shop back in the '70s. I think we paid $25 for it, used. The power supply was a simple RC circuit and it was the size of a lunch box. It had a hand-cranked feedscrew rather than a servo. It worked very well. I spark-eroded a stud out of the head of my Honda motorcycle with it (a frequent need in those days -- Honda's bolts and studs were made of frozen ****), and eroded several taps out of pieces we were working on. The hand feed made it kind of slow, but the real electric servo systems in EDMs are kind of special. Steppers are FAR easier to implement for this job than servo motors, which is why Sodick used them into the 1980s. If you want to know why, I'll explain. What I don't know is if a welder power supply will do it. You might want to take a look at this description of early EDMs from Poco Graphite, which is close to being accurate: http://edmtechman.com/about.cfm?pg=2&chap=1 I think you could try it out by hand, to see if you get the results you want. Take a screw and try repeatedly lift-starting on the end of it. See if it actually eats the screw quickly enough. If so, it will be worth taking the next step. BTW, tap busters did not use liquid dielectric, with few exceptions. They just work in air. Be careful; hot globs can spit out of the hole. Good luck! -- Ed Huntress (former marketing manager for Sodick) |
#4
Posted to rec.crafts.metalworking
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How about a welder for edm power source?
On Saturday, August 15, 2015 at 6:00:47 PM UTC-4, Pete Keillor wrote:
I'd still need to build the carriage, stepper drive, controls, etc. I have a Beaglebone Black which could be applied to that job. I can get a reasonable stepper for $11 from the salvage place in town, plus some linear bearings and a bellows coupler for not much. Any known reasons the welder is a bad idea? Thanks. There are some DIY edm plans on the internet. You might look at some of them for ideas. Many years ago, somewhere around 1969 a friend and I kludged up a edm. We used his drill press for the feed by setting the depth nuts and then leaned on the handle to feed the tool a very small amount. As I remember we used a good sized maybe 500 VA transformer and I think a voltage doubler. A light bulb in series with the supply had low resistanece when things were working and a higher resistance when we had the tool shorting to the work. A kludge , but it worked and we could put square holes into tool steel. We were charging the cap to about 300 volts. So a bunch higher voltage than your welder would supply, but the plans on the internet all use lower voltage. So in answer to your qoestion , I do not know. Dan |
#5
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How about a welder for edm power source?
On Sat, 15 Aug 2015 17:59:24 -0700 (PDT), "
wrote: On Saturday, August 15, 2015 at 6:00:47 PM UTC-4, Pete Keillor wrote: I'd still need to build the carriage, stepper drive, controls, etc. I have a Beaglebone Black which could be applied to that job. I can get a reasonable stepper for $11 from the salvage place in town, plus some linear bearings and a bellows coupler for not much. Any known reasons the welder is a bad idea? Thanks. There are some DIY edm plans on the internet. You might look at some of them for ideas. Many years ago, somewhere around 1969 a friend and I kludged up a edm. We used his drill press for the feed by setting the depth nuts and then leaned on the handle to feed the tool a very small amount. As I remember we used a good sized maybe 500 VA transformer and I think a voltage doubler. A light bulb in series with the supply had low resistanece when things were working and a higher resistance when we had the tool shorting to the work. A kludge , but it worked and we could put square holes into tool steel. We were charging the cap to about 300 volts. So a bunch higher voltage than your welder would supply, but the plans on the internet all use lower voltage. So in answer to your qoestion , I do not know. Dan Thanks all. Lloyd, yeah I'm retired and I think it'd be educational, plus I already spent an hour or two picking and pecking at it. Good ideas, Ed. I might combine that with Dan's drill press idea for a test. I'll try the welder at much lower voltage. If that doesn't work, then I'll ge further into Lanlois' design using some big caps. Pete Keillor |
#6
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How about a welder for edm power source?
On Sun, 16 Aug 2015 07:36:19 -0500, Pete Keillor
wrote: On Sat, 15 Aug 2015 17:59:24 -0700 (PDT), " wrote: On Saturday, August 15, 2015 at 6:00:47 PM UTC-4, Pete Keillor wrote: I'd still need to build the carriage, stepper drive, controls, etc. I have a Beaglebone Black which could be applied to that job. I can get a reasonable stepper for $11 from the salvage place in town, plus some linear bearings and a bellows coupler for not much. Any known reasons the welder is a bad idea? Thanks. There are some DIY edm plans on the internet. You might look at some of them for ideas. Many years ago, somewhere around 1969 a friend and I kludged up a edm. We used his drill press for the feed by setting the depth nuts and then leaned on the handle to feed the tool a very small amount. As I remember we used a good sized maybe 500 VA transformer and I think a voltage doubler. A light bulb in series with the supply had low resistanece when things were working and a higher resistance when we had the tool shorting to the work. A kludge , but it worked and we could put square holes into tool steel. We were charging the cap to about 300 volts. So a bunch higher voltage than your welder would supply, but the plans on the internet all use lower voltage. So in answer to your qoestion , I do not know. Dan Thanks all. Lloyd, yeah I'm retired and I think it'd be educational, plus I already spent an hour or two picking and pecking at it. Good ideas, Ed. I might combine that with Dan's drill press idea for a test. I'll try the welder at much lower voltage. If that doesn't work, then I'll ge further into Lanlois' design using some big caps. Pete Keillor Here's another bit of inside info that may be good to know about -- not that you're trying to build a real EDM, but it may be useful to know how they do it. When they're using a hydrocarbon dielectric (kerosene, for all intents), the voltage required to initiate a spark ranges from 90V to 300V. Keep in mind that their parameters are for producing a highly accurate hole with minimum damage to the workpiece. Around 1980, Agie had the world by the tail with a patented power supply that initiated a spark by using a *string* of lower-voltage pulses at high frequency. The voltage probably was around 90V. The Japanese avoided the patent on their export machines. They didn't worry about it on the machines they sold in Japan. g Anyway, Sodick, for example, broke the process into three steps, without the patented pulse circuit. There is more than one way to skin that cat. First, a high-impedance 300V circuit polarized the channel between the electrode and the workpiece, producing "stringers" of ionized dielectric that reduced resistance for the second step. The second step was a medium-impedance circuit at 150V. This one began to turn the liquid dielectric into a low-resistance channel that delivered enough amperage to turn the dielectric into ionized gas. As it heated up, it became a plasma. The final step was the money step. This one operated more like a welder, at least in terms of delivering power. This was a very low-impedance circuit (nearly a short circuit, with a big capacitor supplying the energy) at around 15V - 30V. This step in the power delivery used the plasma channel to deliver an extremely concentrated spark, which was delivered to the workpiece at a rate of thousands of amperes per square inch. The actual average amperage delivered through the whole cycle might be 30A. Anyway, that's how they did it then. I don't know how they do it now. But it's useful to know that real EDMs employ *sparks*, rather than an *arc*, because an arc is difficult to shut off and it can damage the workpiece. For a tap buster, that's less of a problem. You'll get sparks, and also some arcs. You shut off the arcs the same way you stop it in arc welding -- by pulling the electrode away from the work enough to break the arc. In real EDM, the retraction is only a few thousandths of an inch, at most. That's not enough to stop an arc, so there is a lot of power-supply and servo design directed at producing sparks but not arcs. Again, that will be less of an issue for busting taps, so you don't need all of that complication. But it's good to know what's going on physically in those machines. -- Ed Huntress |
#7
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How about a welder for edm power source?
On Sun, 16 Aug 2015 07:36:19 -0500
Pete Keillor wrote: snip Thanks all. Lloyd, yeah I'm retired and I think it'd be educational, plus I already spent an hour or two picking and pecking at it. I know you want an excuse/reason to build your own EDM but... Jody has a nice youtube video on getting taps and such out with a TIG welder. Which now we know you have a nice one available to use ;-) === "Remove a Broken Tap, Exhaust Stud, or Pressed Pin with TIG welder" https://www.youtube.com/watch?v=ffR2pGVGHbg === -- Leon Fisk Grand Rapids MI/Zone 5b Remove no.spam for email |
#8
Posted to rec.crafts.metalworking
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How about a welder for edm power source?
On Sun, 16 Aug 2015 12:02:51 -0400, Leon Fisk
wrote: On Sun, 16 Aug 2015 07:36:19 -0500 Pete Keillor wrote: snip Thanks all. Lloyd, yeah I'm retired and I think it'd be educational, plus I already spent an hour or two picking and pecking at it. I know you want an excuse/reason to build your own EDM but... Jody has a nice youtube video on getting taps and such out with a TIG welder. Which now we know you have a nice one available to use ;-) === "Remove a Broken Tap, Exhaust Stud, or Pressed Pin with TIG welder" https://www.youtube.com/watch?v=ffR2pGVGHbg === Cool video, Leon. That'll be my first try. Pete |
#9
Posted to rec.crafts.metalworking
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How about a welder for edm power source?
On Sun, 16 Aug 2015 12:46:52 -0500
Pete Keillor wrote: On Sun, 16 Aug 2015 12:02:51 -0400, Leon Fisk wrote: On Sun, 16 Aug 2015 07:36:19 -0500 Pete Keillor wrote: snip Thanks all. Lloyd, yeah I'm retired and I think it'd be educational, plus I already spent an hour or two picking and pecking at it. I know you want an excuse/reason to build your own EDM but... Jody has a nice youtube video on getting taps and such out with a TIG welder. Which now we know you have a nice one available to use ;-) === "Remove a Broken Tap, Exhaust Stud, or Pressed Pin with TIG welder" https://www.youtube.com/watch?v=ffR2pGVGHbg === Cool video, Leon. That'll be my first try. Pete Yeah, Jody makes it look easy-peasy... Some practice runs first, using similar materials of little value would probably be helpful... When I was young and foolish I used to cut/burn out problem items similar to that with an acetylene torch. Nowadays I think I'm too cautious and worry too much about screwing up the good parts some how. Some practice first would be really helpful but it's against my nature to use up consumables in that manner... -- Leon Fisk Grand Rapids MI/Zone 5b Remove no.spam for email |
#10
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How about a welder for edm power source?
On Sun, 16 Aug 2015 14:16:29 -0400, Leon Fisk
wrote: On Sun, 16 Aug 2015 12:46:52 -0500 Pete Keillor wrote: On Sun, 16 Aug 2015 12:02:51 -0400, Leon Fisk wrote: On Sun, 16 Aug 2015 07:36:19 -0500 Pete Keillor wrote: snip Thanks all. Lloyd, yeah I'm retired and I think it'd be educational, plus I already spent an hour or two picking and pecking at it. I know you want an excuse/reason to build your own EDM but... Jody has a nice youtube video on getting taps and such out with a TIG welder. Which now we know you have a nice one available to use ;-) === "Remove a Broken Tap, Exhaust Stud, or Pressed Pin with TIG welder" https://www.youtube.com/watch?v=ffR2pGVGHbg === Cool video, Leon. That'll be my first try. Pete Yeah, Jody makes it look easy-peasy... Some practice runs first, using similar materials of little value would probably be helpful... When I was young and foolish I used to cut/burn out problem items similar to that with an acetylene torch. Nowadays I think I'm too cautious and worry too much about screwing up the good parts some how. Some practice first would be really helpful but it's against my nature to use up consumables in that manner... Yeah, I'm nowhere near as steady on my best day as the guy in the video. I'll practice. A 4-40 tap is one tiny target. I remember an old gunsmithing trick to remove a busted tap in a receiver; hit the tap with the oa torch, the tap will heat up much more quickly than the receiver. Then hit it with just oxy. One short burst and a shower of sparks... But I don't have the nerve to try that. Pete |
#11
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How about a welder for edm power source?
On Sun, 16 Aug 2015 13:51:31 -0500
Pete Keillor wrote: snip Yeah, I'm nowhere near as steady on my best day as the guy in the video. I'll practice. A 4-40 tap is one tiny target. Don't let Jody fool you. He takes advantage of any sort of prop/bracing technique to steady himself that he can think of. He quite often will grab hold of the electrode (welding gloves on) while stick (SMAW) welding to keep it steady. I've never had the opportunity to try TIG welding but would try resting the cup on something convenient for trying to build up your broken tap. I remember an old gunsmithing trick to remove a busted tap in a receiver; hit the tap with the oa torch, the tap will heat up much more quickly than the receiver. Then hit it with just oxy. One short burst and a shower of sparks... But I don't have the nerve to try that. Yeah, that's the kind of stuff I remember doing as a dumb teenager. Bolt broke off in a casting, just blow it out of there with the torch. Never gave the consequences of screwing up a second thought... Of course I used to ride my motorcycle down the road back then at night too. Full throttle (~65mph), no headlight... if I stared straight ahead my peripheral vision would register the sides of the road. I tried to stay in the middle somewhere. I added a second headlight to my Honda Magna and would really rather not ride at night if at all possible :-) -- Leon Fisk Grand Rapids MI/Zone 5b Remove no.spam for email |
#12
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How about a welder for edm power source?
On Sun, 16 Aug 2015 12:46:52 -0500, Pete Keillor
wrote: On Sun, 16 Aug 2015 12:02:51 -0400, Leon Fisk wrote: On Sun, 16 Aug 2015 07:36:19 -0500 Pete Keillor wrote: snip Thanks all. Lloyd, yeah I'm retired and I think it'd be educational, plus I already spent an hour or two picking and pecking at it. I know you want an excuse/reason to build your own EDM but... Jody has a nice youtube video on getting taps and such out with a TIG welder. Which now we know you have a nice one available to use ;-) === "Remove a Broken Tap, Exhaust Stud, or Pressed Pin with TIG welder" https://www.youtube.com/watch?v=ffR2pGVGHbg === Cool video, Leon. That'll be my first try. That guy is a great tutor, isn't he? I like his vids a lot. They're clear, bright, and consistent. -- The beauty of the 2nd Amendment is that it will not be needed until they try to take it. --Thomas Jefferson |
#13
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How about a welder for edm power source?
On Sun, 16 Aug 2015 07:36:19 -0500, Pete Keillor
wrote: On Sat, 15 Aug 2015 17:59:24 -0700 (PDT), " wrote: On Saturday, August 15, 2015 at 6:00:47 PM UTC-4, Pete Keillor wrote: I'd still need to build the carriage, stepper drive, controls, etc. I have a Beaglebone Black which could be applied to that job. I can get a reasonable stepper for $11 from the salvage place in town, plus some linear bearings and a bellows coupler for not much. Any known reasons the welder is a bad idea? Thanks. There are some DIY edm plans on the internet. You might look at some of them for ideas. Many years ago, somewhere around 1969 a friend and I kludged up a edm. We used his drill press for the feed by setting the depth nuts and then leaned on the handle to feed the tool a very small amount. As I remember we used a good sized maybe 500 VA transformer and I think a voltage doubler. A light bulb in series with the supply had low resistanece when things were working and a higher resistance when we had the tool shorting to the work. A kludge , but it worked and we could put square holes into tool steel. We were charging the cap to about 300 volts. So a bunch higher voltage than your welder would supply, but the plans on the internet all use lower voltage. So in answer to your qoestion , I do not know. Dan Thanks all. Lloyd, yeah I'm retired and I think it'd be educational, plus I already spent an hour or two picking and pecking at it. Good ideas, Ed. I might combine that with Dan's drill press idea for a test. I'll try the welder at much lower voltage. If that doesn't work, then I'll ge further into Lanlois' design using some big caps. Pete Keillor You guys may..may wish to simply buy a used EDM machine. Used but working good machines are simply thrown away all over the US because they have become "obsolete" Wire, sinker, spark....Ive tried to find buyers and wound up pushing them into scrappers trucks with a forklift off the loading docks. Ive destroyed at least 4 of these in the past 10 yrs..simply because no one wanted them..and they were ALL in good working shape http://www.ebay.com/itm/Electro-Arc-...item3cff60b45c |
#14
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How about a welder for edm power source?
On Sun, 16 Aug 2015 12:02:51 -0400, Leon Fisk
wrote: On Sun, 16 Aug 2015 07:36:19 -0500 Pete Keillor wrote: snip Thanks all. Lloyd, yeah I'm retired and I think it'd be educational, plus I already spent an hour or two picking and pecking at it. I know you want an excuse/reason to build your own EDM but... Jody has a nice youtube video on getting taps and such out with a TIG welder. Which now we know you have a nice one available to use ;-) === "Remove a Broken Tap, Exhaust Stud, or Pressed Pin with TIG welder" https://www.youtube.com/watch?v=ffR2pGVGHbg === You can do a fair amount of that with careful use of a stick welder as well https://picasaweb.google.com/1040422...99967411797682 https://picasaweb.google.com/1040422...99997476568770 |
#15
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How about a welder for edm power source?
Jody has a nice youtube video on getting taps and such out with a TIG welder. Which now we know you have a nice one available to use ;-) I guess I'm lucky (know I'm blessed!). I haven't broken off a tap in the work in about five years. I do make sure they're all sharp, and go straight-in into a properly-sized tap hole. Lloyd |
#16
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How about a welder for edm power source?
On Sun, 16 Aug 2015 16:41:52 -0500, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote: Jody has a nice youtube video on getting taps and such out with a TIG welder. Which now we know you have a nice one available to use ;-) I guess I'm lucky (know I'm blessed!). I haven't broken off a tap in the work in about five years. I do make sure they're all sharp, and go straight-in into a properly-sized tap hole. Lloyd This was a new Greenfield, so I can't blame the tap, and it was well in the hole, just my wobble. Also couldn't use my bench block. Maybe a hand tapping machine would be a better use of my time than an edm. We'll see how the welding goes after I practice. Pete |
#17
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How about a welder for edm power source?
Pete Keillor fired this volley in
: Maybe a hand tapping machine would be a better use of my time than an edm. I don't usually buy Chinese tools unless they're for one-off jobs, but I got a (pretty) nice hand-tapper from Enco that only required a couple of small mods to make it a worthwhile shop addition. It's probably part of the reason my "tap breakage ratio" has fallen off from historical figures. LLoyd |
#18
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How about a welder for edm power source?
In article , Pete Keillor
wrote: On Sat, 15 Aug 2015 17:59:24 -0700 (PDT), " wrote: On Saturday, August 15, 2015 at 6:00:47 PM UTC-4, Pete Keillor wrote: I'd still need to build the carriage, stepper drive, controls, etc. I have a Beaglebone Black which could be applied to that job. I can get a reasonable stepper for $11 from the salvage place in town, plus some linear bearings and a bellows coupler for not much. Any known reasons the welder is a bad idea? Thanks. There are some DIY edm plans on the internet. You might look at some of them for ideas. Many years ago, somewhere around 1969 a friend and I kludged up a edm. We used his drill press for the feed by setting the depth nuts and then leaned on the handle to feed the tool a very small amount. As I remember we used a good sized maybe 500 VA transformer and I think a voltage doubler. A light bulb in series with the supply had low resistanece when things were working and a higher resistance when we had the tool shorting to the work. A kludge , but it worked and we could put square holes into tool steel. We were charging the cap to about 300 volts. So a bunch higher voltage than your welder would supply, but the plans on the internet all use lower voltage. So in answer to your qoestion , I do not know. Dan Thanks all. Lloyd, yeah I'm retired and I think it'd be educational, plus I already spent an hour or two picking and pecking at it. Good ideas, Ed. I might combine that with Dan's drill press idea for a test. I'll try the welder at much lower voltage. If that doesn't work, then I'll ge further into Lanlois' design using some big caps. Make sure that no spark energy goes through the ball bearings. Insulate the tool from the drill press, and put a short circuit between DP chuck and DP frame. Joe Gwinn |
#19
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How about a welder for edm power source?
On Monday, August 17, 2015 at 9:00:16 AM UTC-4, Joe Gwinn wrote:
Make sure that no spark energy goes through the ball bearings. Insulate the tool from the drill press, and put a short circuit between DP chuck and DP frame. Joe Gwinn I should have mentioned that. We used a wood dowel in the drill press chuck and whatever shaped tool attached to the other end of the dowel. To be safe we should have had some sort of guard around the tool to keep anyone from touching the tool. Dan |
#20
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How about a welder for edm power source?
On 8/16/2015 1:51 PM, Pete Keillor wrote:
On Sun, 16 Aug 2015 14:16:29 -0400, Leon Fisk wrote: On Sun, 16 Aug 2015 12:46:52 -0500 Pete Keillor wrote: On Sun, 16 Aug 2015 12:02:51 -0400, Leon Fisk wrote: On Sun, 16 Aug 2015 07:36:19 -0500 Pete Keillor wrote: snip Thanks all. Lloyd, yeah I'm retired and I think it'd be educational, plus I already spent an hour or two picking and pecking at it. I know you want an excuse/reason to build your own EDM but... Jody has a nice youtube video on getting taps and such out with a TIG welder. Which now we know you have a nice one available to use ;-) === "Remove a Broken Tap, Exhaust Stud, or Pressed Pin with TIG welder" https://www.youtube.com/watch?v=ffR2pGVGHbg === Cool video, Leon. That'll be my first try. Pete Yeah, Jody makes it look easy-peasy... Some practice runs first, using similar materials of little value would probably be helpful... When I was young and foolish I used to cut/burn out problem items similar to that with an acetylene torch. Nowadays I think I'm too cautious and worry too much about screwing up the good parts some how. Some practice first would be really helpful but it's against my nature to use up consumables in that manner... Yeah, I'm nowhere near as steady on my best day as the guy in the video. I'll practice. A 4-40 tap is one tiny target. I remember an old gunsmithing trick to remove a busted tap in a receiver; hit the tap with the oa torch, the tap will heat up much more quickly than the receiver. Then hit it with just oxy. One short burst and a shower of sparks... But I don't have the nerve to try that. Pete I used to have a very limited aluminum production item with 14 4-40 holes that I tapped. After I spent a few hours mechanically removing broken taps, I switched it over to 6-32. My life was easier. Also soon after that I bought a HSS tap locally and that was the best tap I ever used in aluminum. I have limited metal working experience, just got lucky when I needed a tap. Don't really know what it was, just labelled HSS. Mikek --- This email has been checked for viruses by Avast antivirus software. http://www.avast.com |
#21
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How about a welder for edm power source?
On Sun, 16 Aug 2015 14:19:38 -0700, Gunner Asch
wrote: On Sun, 16 Aug 2015 07:36:19 -0500, Pete Keillor wrote: On Sat, 15 Aug 2015 17:59:24 -0700 (PDT), " wrote: On Saturday, August 15, 2015 at 6:00:47 PM UTC-4, Pete Keillor wrote: I'd still need to build the carriage, stepper drive, controls, etc. I have a Beaglebone Black which could be applied to that job. I can get a reasonable stepper for $11 from the salvage place in town, plus some linear bearings and a bellows coupler for not much. Any known reasons the welder is a bad idea? Thanks. There are some DIY edm plans on the internet. You might look at some of them for ideas. Many years ago, somewhere around 1969 a friend and I kludged up a edm. We used his drill press for the feed by setting the depth nuts and then leaned on the handle to feed the tool a very small amount. As I remember we used a good sized maybe 500 VA transformer and I think a voltage doubler. A light bulb in series with the supply had low resistanece when things were working and a higher resistance when we had the tool shorting to the work. A kludge , but it worked and we could put square holes into tool steel. We were charging the cap to about 300 volts. So a bunch higher voltage than your welder would supply, but the plans on the internet all use lower voltage. So in answer to your qoestion , I do not know. Dan Thanks all. Lloyd, yeah I'm retired and I think it'd be educational, plus I already spent an hour or two picking and pecking at it. Good ideas, Ed. I might combine that with Dan's drill press idea for a test. I'll try the welder at much lower voltage. If that doesn't work, then I'll ge further into Lanlois' design using some big caps. Pete Keillor You guys may..may wish to simply buy a used EDM machine. Used but working good machines are simply thrown away all over the US because they have become "obsolete" Wire, sinker, spark....Ive tried to find buyers and wound up pushing them into scrappers trucks with a forklift off the loading docks. Ive destroyed at least 4 of these in the past 10 yrs..simply because no one wanted them..and they were ALL in good working shape http://www.ebay.com/itm/Electro-Arc-...item3cff60b45c It's a shame they're going to the dump/scrap yard, but at $1k to ship plus a lot of space to set it up, it's no big wonder. Are smaller units built? I'll bet tiny EDMs find new homes a lot more easily, especially with hobbyists like us. -- The beauty of the 2nd Amendment is that it will not be needed until they try to take it. --Thomas Jefferson |
#22
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How about a welder for edm power source?
On Mon, 17 Aug 2015 18:23:26 -0700, Larry Jaques
wrote: On Sun, 16 Aug 2015 14:19:38 -0700, Gunner Asch wrote: On Sun, 16 Aug 2015 07:36:19 -0500, Pete Keillor wrote: On Sat, 15 Aug 2015 17:59:24 -0700 (PDT), " wrote: On Saturday, August 15, 2015 at 6:00:47 PM UTC-4, Pete Keillor wrote: I'd still need to build the carriage, stepper drive, controls, etc. I have a Beaglebone Black which could be applied to that job. I can get a reasonable stepper for $11 from the salvage place in town, plus some linear bearings and a bellows coupler for not much. Any known reasons the welder is a bad idea? Thanks. There are some DIY edm plans on the internet. You might look at some of them for ideas. Many years ago, somewhere around 1969 a friend and I kludged up a edm. We used his drill press for the feed by setting the depth nuts and then leaned on the handle to feed the tool a very small amount. As I remember we used a good sized maybe 500 VA transformer and I think a voltage doubler. A light bulb in series with the supply had low resistanece when things were working and a higher resistance when we had the tool shorting to the work. A kludge , but it worked and we could put square holes into tool steel. We were charging the cap to about 300 volts. So a bunch higher voltage than your welder would supply, but the plans on the internet all use lower voltage. So in answer to your qoestion , I do not know. Dan Thanks all. Lloyd, yeah I'm retired and I think it'd be educational, plus I already spent an hour or two picking and pecking at it. Good ideas, Ed. I might combine that with Dan's drill press idea for a test. I'll try the welder at much lower voltage. If that doesn't work, then I'll ge further into Lanlois' design using some big caps. Pete Keillor You guys may..may wish to simply buy a used EDM machine. Used but working good machines are simply thrown away all over the US because they have become "obsolete" Wire, sinker, spark....Ive tried to find buyers and wound up pushing them into scrappers trucks with a forklift off the loading docks. Ive destroyed at least 4 of these in the past 10 yrs..simply because no one wanted them..and they were ALL in good working shape http://www.ebay.com/itm/Electro-Arc-...item3cff60b45c It's a shame they're going to the dump/scrap yard, but at $1k to ship plus a lot of space to set it up, it's no big wonder. Are smaller units built? I'll bet tiny EDMs find new homes a lot more easily, especially with hobbyists like us. Old Hansvedt benchtop machines. They were pretty good. You did need a big benchtop, but they were about the smallest sinker EDMs around. -- Ed Huntress |
#23
Posted to rec.crafts.metalworking
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How about a welder for edm power source?
On Mon, 17 Aug 2015 18:23:26 -0700, Larry Jaques
wrote: On Sun, 16 Aug 2015 14:19:38 -0700, Gunner Asch wrote: On Sun, 16 Aug 2015 07:36:19 -0500, Pete Keillor wrote: On Sat, 15 Aug 2015 17:59:24 -0700 (PDT), " wrote: On Saturday, August 15, 2015 at 6:00:47 PM UTC-4, Pete Keillor wrote: I'd still need to build the carriage, stepper drive, controls, etc. I have a Beaglebone Black which could be applied to that job. I can get a reasonable stepper for $11 from the salvage place in town, plus some linear bearings and a bellows coupler for not much. Any known reasons the welder is a bad idea? Thanks. There are some DIY edm plans on the internet. You might look at some of them for ideas. Many years ago, somewhere around 1969 a friend and I kludged up a edm. We used his drill press for the feed by setting the depth nuts and then leaned on the handle to feed the tool a very small amount. As I remember we used a good sized maybe 500 VA transformer and I think a voltage doubler. A light bulb in series with the supply had low resistanece when things were working and a higher resistance when we had the tool shorting to the work. A kludge , but it worked and we could put square holes into tool steel. We were charging the cap to about 300 volts. So a bunch higher voltage than your welder would supply, but the plans on the internet all use lower voltage. So in answer to your qoestion , I do not know. Dan Thanks all. Lloyd, yeah I'm retired and I think it'd be educational, plus I already spent an hour or two picking and pecking at it. Good ideas, Ed. I might combine that with Dan's drill press idea for a test. I'll try the welder at much lower voltage. If that doesn't work, then I'll ge further into Lanlois' design using some big caps. Pete Keillor You guys may..may wish to simply buy a used EDM machine. Used but working good machines are simply thrown away all over the US because they have become "obsolete" Wire, sinker, spark....Ive tried to find buyers and wound up pushing them into scrappers trucks with a forklift off the loading docks. Ive destroyed at least 4 of these in the past 10 yrs..simply because no one wanted them..and they were ALL in good working shape http://www.ebay.com/itm/Electro-Arc-...item3cff60b45c It's a shame they're going to the dump/scrap yard, but at $1k to ship plus a lot of space to set it up, it's no big wonder. Are smaller units built? I'll bet tiny EDMs find new homes a lot more easily, especially with hobbyists like us. It depends on what sort of EDM is in question. The simplist are spark eroders..tap busters..all the way up through wire edms. http://www.polcraft.com/edm2.htm What is EDM? EDM stands for Electrical Discharge Machining. The basic concept of EDM is that you use an electrode to erode a workpiece using electrical sparks. The electricity flows through the electrode in the form of a square wave attacking the points of least resistance on the workpiece similar to how a bolt of lightning would hit a tree before it hits the ground. This "Zap" happens every time the current is switched on in the square wave and then the current is switched off to allow the debree to be flushed away. This process happens over and over many times a second as the electrode is slowly advanced deeper and deeper into the cut. The electrode never touches the workpiece because the actual cutting is being done by the spark gap between the electrode and the workpiece. The process takes place submerged in a dielectric fluid such as deionized water or dielectric oil. This fluid acts like the vacuum in a light bulb. If you break a light bulb, the fillament which has current flowing through it becomes oxidized and burns out. The same would happen if you tried to EDM without any dielectric, the electrode and workpiece would become oxidized and would not be able to perform the cut. The Dielectric fluid performs multiple tasks; 1) Providing an inert atmosphere in which the process can take place. 2) Flushes the removed material or debree away from the gap. 3) Keeps the gap cool and the temperature of the whole process stable. There are three main types of EDM which are different according to the type of electrode used. Wire EDM cutting honeycomb stainless steel Wire EDM in which the electrode is a brass wire that comes off a spool and is fed through an upper and lower diamond guide and then discarded after it is used. The wire is controlled by a CNC control which allows you to program a path for the wire to travel along sort of like a super precision band saw. The wire can range from .0120 to ..0008 inches in diameter. This form of EDM is the most accurate and is able to hold size well under .0001 inches. Sinker EDM Sinker EDM in which the electrode is a machined shape made of materials like graphite, copper, or copper-tungsten (to name a few) and the machine uses this shape to erode the inverse shape in the workpiece. This process is also very accurate and commonly used to burn mold cavities where the electrode starts out the shape of the final molded part and is used to erode a cavity in a mold that is later used to make thousands or millions of parts. EDM drill Small hole EDM drill ("Hole Popper") in which the electrode is a brass or copper tube ranging from .004 to .250 inches in diameter that is used to blast holes through the workpiece. This process is similar to Sinker EDM except that sinkers have very sensitive power supplies to protect and conserve the electrode and the popper has a very aggressive power supply to blast through the workpiece very quickly. This type of EDM compliments the wire EDM by providing the ability to drill pilot holes through heat treated materials and carbide so that you can thread the wire through this pilot hole for a place to start your wire cut. Polcraft inc. employs all three types of EDM in addition to CNC and conventional milling and turning to eliminate any out sourcing of the manufacturing process so you get high quality parts in a timely fashion. (there is actually 4 kinds...the lowly tap buster being the first kind..but its generally covered under EDM drill.... Check the photos... http://www.mercatech.com/EDM%20Guide...20is%20EDM.htm Gunner |
#24
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How about a welder for edm power source?
On Wed, 26 Aug 2015 11:43:18 -0700 (PDT), SteamboatEd Haas
wrote: On Saturday, August 15, 2015 at 3:00:47 PM UTC-7, Pete Keillor wrote: I broke a 4-40 tap in my filing machine casting. It was for the top cap, which is there to hold packing as a seal for the file rod, so not that big of a deal since there are five good screws. But it feels like a berry seed in my tooth. Aggravating. I got Langlois' book on building a hobbyist edm, but have a few other thoughts. I have a very nice tig welder, Miller Dynasty 200DX. In tig mode, it'll go down to 1A DC or 5A AC, plus a pulser on dc up to 250 Hz and lots of control over ac frequency and wave form. Seems I might be able to use it in lift start mode for edm. I'd still need to build the carriage, stepper drive, controls, etc. I have a Beaglebone Black which could be applied to that job. I can get a reasonable stepper for $11 from the salvage place in town, plus some linear bearings and a bellows coupler for not much. Any known reasons the welder is a bad idea? Thanks. Pete Keillor Well if you're anywhere near Santa Rosa, CA I've got an old Hansvedt tap buster that we recently rebuilt... ;-) Unfortunately nowhere near. I tried the welder. Made a cylindrical back cap out of delrin and brass, chucked in the drill press with the test piece well insulated and the chuck grounded to the column. It didn't do much. I tried ac, dc, varied frequency, pulser, etc. Interesting, but I'm not going to live long enough to get anything useful done. Oh, tried welding the tap too. finally got some ss welded on the tiny tap, but it broke off deep in the hole when I tried it. Then even with a sharp .040" tungsten, the arc just raced around the cast iron in a little circle. By the way, +2.5 diopter cheaters in the hood plus my 18" focal length safety glasses gave me a good close view of the arc and work area. Looks like Ed was right. Langlois' book talks about switching in capacitors for more spark, up to 700 microfarads. So I'm going to start that way, putting together a list of stuff the surplus place in town has available. |
#25
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How about a welder for edm power source?
--Did you submerge the operation in a dielectric like mineral oil? It doesn't really work unless the arc is constrained by some sort of goo.
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#26
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How about a welder for edm power source?
On Fri, 28 Aug 2015 16:29:23 -0700 (PDT), SteamboatEd Haas
wrote: --Did you submerge the operation in a dielectric like mineral oil? It doesn't really work unless the arc is constrained by some sort of goo. I didn't, based on Huntress' suggestion that the tap burners he used were run in air. Might try that sometime, but found a commercial edm shop nearby with a $75 hourly rate that said they could do it in under an hour, so we'll see. Definitely cheaper than all those caps, transformers, etc., even surplus. I am going to invest in a hand tapping machine, though. Well worth it. Pete Keillor |
#27
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How about a welder for edm power source?
On Wed, 02 Sep 2015 09:01:36 -0500, Pete Keillor
wrote: On Fri, 28 Aug 2015 16:29:23 -0700 (PDT), SteamboatEd Haas wrote: --Did you submerge the operation in a dielectric like mineral oil? It doesn't really work unless the arc is constrained by some sort of goo. I didn't, based on Huntress' suggestion that the tap burners he used were run in air. Might try that sometime, but found a commercial edm shop nearby with a $75 hourly rate that said they could do it in under an hour, so we'll see. Definitely cheaper than all those caps, transformers, etc., even surplus. I am going to invest in a hand tapping machine, though. Well worth it. Pete Keillor Yeah, the basic tap busters were just run in air. An oil dielectric allows the electrode to get closer for more precise sparking, but it requires a really good touch (or a decent servo mechanism) to keep the spark distance in the right range. Sometimes you can get a used one cheap, I think it's more trouble and expense to make your own than it's worth. 'Too bad the welder didn't work. I had a feeling that it would be difficult, but it was worth a try. -- Ed Huntress |
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