Changing tapped machine to a continuous?

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Just wondering if this can be done, I don't plan on doing it anytime with the next couple years but I'm curious, I love my lincoln 215 and don't want to mess with it right now, don't really want to get a new welder, and with funds the way they are these day's couldn't possibly dig up the cash to do so anyways.  Just pondering the idea really, cause some days you just wish you could tweak it just a little bit better. So, who's got some thoughts on the subject?looking at new trucks while carrying two car seats around the parking lot to "test fit".......humiliating.
Reply:Leave the taps, but add a rheostat!#1. If you don't like what I wrote, or if it offends you, then don't read it!#2. I am living life the way I see fit, if you don't like the way I'M living, tough sh**!
Reply:While being technically correct, it’s not practical. The rheostat would have to be huge, able to dissipate tons of heat and would violate the constant voltage ability of the mig’s power supply, it would not be able to self regulate the input and output voltage. You would have to keep one hand on the rheostat to continuously adjust the input power at a split second, that is what the electronics on the control board is all about, once the heat is set [voltage] the smarts keeps the input power relativity constant. Now if you want to re-invent the wheel and find a control board from some manufacture that will work……., or perhaps roll your own, and engineer the electronics from scratch, by the time your finished you would have spent many more times the cost of replacement in $$$ and man-hours. Now let’s stop by our local salvage yard, pick up some odds and ends and build our own aircraft carrier……
Reply:Actually the operating ranges of those taps overlap a decent amount depending on which wire, wire speed, a lot of variables. What you are really doing is setting the ceiling more than choosing a specific voltage. You can make subtle adjustments to the load and arc voltage by extending or shortening the contact tip to work distance, move in or out to get the effect you want, make a mental note of the preheat length each time you stop, bump the wire speed up or down just a smidge, things like that. Not infinite adjustment but it helps a lot.What you can do that may help is take a digital vom and make a quick & easy log of the approximate OCV for each tap. Of course at about a ten to one ratio it is going to vary a subtle amount from day to day as the input power varies, but you'll get an idea of what the cap is. Keep in mind the cap will not be attainable because as soon as you establish an arc the voltage will be lower than that measured OCV.  An example here is if a tap measured 19.2 OCV and a particular wire specs out needing 19 volts for proper operation then that tap isn't gonna cut it. Move up to the next tap.  A lot of little things you can do.
Reply:Originally Posted by SandyActually the operating ranges of those taps overlap a decent amount depending on which wire, wire speed, a lot of variables. What you are really doing is setting the ceiling more than choosing a specific voltage. You can make subtle adjustments to the load and arc voltage by extending or shortening the contact tip to work distance, move in or out to get the effect you want, make a mental note of the preheat length each time you stop, bump the wire speed up or down just a smidge, things like that. Not infinite adjustment but it helps a lot.What you can do that may help is take a digital vom and make a quick & easy log of the approximate OCV for each tap. Of course at about a ten to one ratio it is going to vary a subtle amount from day to day as the input power varies, but you'll get an idea of what the cap is. Keep in mind the cap will not be attainable because as soon as you establish an arc the voltage will be lower than that measured OCV.  An example here is if a tap measured 19.2 OCV and a particular wire specs out needing 19 volts for proper operation then that tap isn't gonna cut it. Move up to the next tap.  A lot of little things you can do.
Reply:Swampy,Here's a small chart I made up for myself. Keep in mind the load voltages really are general and were derived at using .035 flux core and done only to get a ruff idea of what I might get off any particular tap. Larger wire, smaller wire, solid vs flux core, all will produce different readings and what you might consider a good bead could possibly be different than what I would think but it gives you an idea of what to expect from each tap on a PM215. Also remember your local PoCo input could be slightly different than mine at any given time. Probably should have moved on to a larger wire for the higher taps but I wasn't really in the mood to go to that much work.   I should refine it as time goes on but normally when it's running sweet the actual readings don't mean a lot. This is a cut and paste from a spreadsheet so we'll see.  Aprx. TAP Voltage RangesTapOCV ± 1LV ± 2A16.58~13.00B19.70~14.80C22.80~15.90D26.05~20.50E29.25~21.30F32.45~23.60G35.50~25.60
Reply:I’m not sure what you are telling me? I don’t understand how you arrived at the values in the second column. Is it the voltage while welding?    OCV............... WELDING VOLTAGEA 16.58....................   13.00
Reply:Originally Posted by transit....................... I don’t understand how you arrived at the values in the second column. Is it the voltage while welding?    OCV............... WELDING VOLTAGEA 16.58....................   13.00
Reply:The only adjustments you have are;Course settings [voltage]The step heat settingSelecting the wire diameter Type of wire, solid or flux coreFine adjustment;Wire speed [current]SickoutThe welding voltages are about 70% of the OCV.Fully adjustable heat would be nice but not easily done. Sorry.
Reply:Originally Posted by transit...............................Fully adjustable heat would be nice but not easily done. Sorry.
Reply:To the OP,  Short answer : Nope.psst, Sandy, one nice aspect of the continuously adjustable machines is the ability to tweak the voltage -while- welding.    But a tapped machine with decent tap 'positions' is certainly fine too.    The best laid schemes ... Gang oft agley ...
Reply:thanks for the input, like I said at the beginning, this is all completly theoretical, I'm very happy with my 215, and if I ever feel the need for continuous I'll just go get a 255 while the wife ain't looking....looking at new trucks while carrying two car seats around the parking lot to "test fit".......humiliating.
Reply:I'm wondering if a potentiometer (or some similar variable device) could be put in as a fine voltage control for each tap setting, like some engine drive machines have.  My Bobcat is like that.  It has High and Low on the CV side and then you fine tune it with the dial.   Same with the CC side, but there are more taps on that side.  My HTP mig has 2 sets of taps.  The first is the main taps, then there is a fine tap control that adjusts within each main tap range.  Neither control is continuously variable, both are set taps, but it works well.  Trouble is remembering the combinations that work best for each situation.  That's why I like one continuously variable control with a digital meter, which my 350P and XMT both have, much easier to set up the machine.MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op
Reply:Might be impossible.Many continuous machines have SCR's that require gated electronic controls.  Most are even digital nowdays.  It would not be worth the cost and effort, and would require a redesign by a heavy EE.
Reply:Originally Posted by obewanMight be impossible.Many continuous machines have SCR's that require gated electronic controls.  Most are even digital nowdays.  It would not be worth the cost and effort, and would require a redesign by a heavy EE.