Shop Floor Talk  

Go Back   Shop Floor Talk > Welding and Metalworking Forums > Welding

SFT Search:   
Reply
 
Thread Tools Display Modes
  #11  
Old 01-10-2017, 08:54 PM
rustythe4x4's Avatar
rustythe4x4 rustythe4x4 is offline
Elite Member
 
Join Date: Oct 2010
Location: Saskatchewan
Posts: 1,437
Default

Even the cheap wire feeders will be DC.

Don't bother trying to stick weld with it. You will be less than happy with the results.
Go buy yourself an old AC machine off craigslist and rectify that with diodes. It will be a hundred times better, and cheaper.
__________________
Living the country life


Learning boils down to "Repetition or the avoidance of pain", some people learn by doing, some by watching and some have to pee on the electric fence. - Norm W.

Mathew 10:36
And a man's foes shall be they of his own household
-Ironman quoting the Bible
Reply With Quote
  #12  
Old 01-10-2017, 10:27 PM
milomilo's Avatar
milomilo milomilo is offline
Auction Addict
 
Join Date: May 2010
Location: Wheatland, Wyoming
Posts: 11,454
Default

I did a conversion on an old ac machine and used 300 amp diodes. Did not lose any amps.
__________________
Chris

Loyalty to the Nation all the time, loyalty to the Government when it deserves it. Mark Twain
Reply With Quote
  #13  
Old 01-10-2017, 11:09 PM
Ironman's Avatar
Ironman Ironman is offline
Iron Modification Investigator
 
Join Date: Feb 2008
Location: Warburg, Alberta, Canada
Posts: 11,332
Default

Quote:
Originally Posted by MAC702 View Post
Rectifying doesn't cut off peaks, it just puts them all on the same polarity, assuming full wave bridge rectifying.
You are correct. I was just trying to make it easy for him to understand with out AmishCAD drawing of sine waves, etc.
__________________
Gerry
It is tempting to blame others for all this, especially those in control of the system, but don’t forget that for decades you voted for people who routinely lied before elections, and told you what you wanted to hear, that you could have it all right now and to hell with the future – well, that future has now arrived. Clive Maund

Even duct tape can't fix stupid ... But it can muffle the sound.
Reply With Quote
  #14  
Old 01-11-2017, 01:38 AM
Rufus Rufus is offline
Senior Member
 
Join Date: Feb 2007
Location: Maineville Ohio
Posts: 752
Send a message via AIM to Rufus Send a message via Yahoo to Rufus
Default

Quote:
Originally Posted by rustythe4x4 View Post
Even the cheap wire feeders will be DC.

Don't bother trying to stick weld with it. You will be less than happy with the results.
Go buy yourself an old AC machine off craigslist and rectify that with diodes. It will be a hundred times better, and cheaper.
I have a Miller Thunderbolt XL 225 AC machine that I am giving some strong thought to turning it over to a AC/DC machine. I have a diode for it (160) and may just buy a bridge rectifier than to buy three more diodes for it.

Thanks
Tim
__________________
Hey! What do ya'll say we go to Wallys house?!?!?!
Reply With Quote
  #15  
Old 01-11-2017, 07:11 AM
Ironman's Avatar
Ironman Ironman is offline
Iron Modification Investigator
 
Join Date: Feb 2008
Location: Warburg, Alberta, Canada
Posts: 11,332
Default

I used to have one of those. I personally would use the 4 diodes and a couple of good heat sinks. Welding diodes are like football players, they take alot of hits, and if one fails the rest are ok. The large full wave assembly is easy to mount and harder to cool.
I have used the threaded stud type of rectifier diodes and re-threaded the spark plug hole in an aluminum single cylinder head. Big and awkward but does a great job of cooling the diode.

This was for a 200 amp 24 volt battery charger. The manufacturers seemed to like selenium rectifiers and the small town dumps always have a few very nice thrown away battery chargers after the rectifier pack fails.
__________________
Gerry
It is tempting to blame others for all this, especially those in control of the system, but don’t forget that for decades you voted for people who routinely lied before elections, and told you what you wanted to hear, that you could have it all right now and to hell with the future – well, that future has now arrived. Clive Maund

Even duct tape can't fix stupid ... But it can muffle the sound.
Reply With Quote
  #16  
Old 01-11-2017, 02:53 PM
Rufus Rufus is offline
Senior Member
 
Join Date: Feb 2007
Location: Maineville Ohio
Posts: 752
Send a message via AIM to Rufus Send a message via Yahoo to Rufus
Default

Quote:
Originally Posted by Ironman View Post
I used to have one of those. I personally would use the 4 diodes and a couple of good heat sinks. Welding diodes are like football players, they take alot of hits, and if one fails the rest are ok. The large full wave assembly is easy to mount and harder to cool.
I have used the threaded stud type of rectifier diodes and re-threaded the spark plug hole in an aluminum single cylinder head. Big and awkward but does a great job of cooling the diode.

This was for a 200 amp 24 volt battery charger. The manufacturers seemed to like selenium rectifiers and the small town dumps always have a few very nice thrown away battery chargers after the rectifier pack fails.
Gerry:
You can find all kinds of Bridge rectifiers on ebay all day at cheap prices. For example, here is a 150 Amp, bridge rectifier for only $9.79. However, even if it from Hong Kong it shouldn't be a problem. I am going to do a google search and see what I can come up with as to any sold here in the U.S.

Thanks
Tim
__________________
Hey! What do ya'll say we go to Wallys house?!?!?!
Reply With Quote
  #17  
Old 01-11-2017, 03:33 PM
moe1942's Avatar
moe1942 moe1942 is offline
Voice of Experience
 
Join Date: Jun 2004
Location: Alexandria, Louisiana
Posts: 10,709
Default

Rufus do yourself a favor and ditch the HF "welder". Nothing but an exercise if frustration...
__________________
Don't pick a fight with an old man. If he is too old to fight, he'll just kill you... John Steinbeck

"If we ever forget that we're one nation under God, then we will
be a nation gone under". ~Ronald Reagan

We should have picked our own cotton...

I love my women hot and my beer ice cold..
Reply With Quote
  #18  
Old 01-11-2017, 03:44 PM
Rufus Rufus is offline
Senior Member
 
Join Date: Feb 2007
Location: Maineville Ohio
Posts: 752
Send a message via AIM to Rufus Send a message via Yahoo to Rufus
Default

Quote:
Originally Posted by moe1942 View Post
Rufus do yourself a favor and ditch the HF "welder". Nothing but an exercise if frustration...

No, no, no lol. I'm not doing the HF welder. I was just explaining that I found people doing mods to make those HF welders into DC output welders. I was thinking about converting my Miller Thunderbolt XL into a DC machine. I found the rectifier assembly I would need that fits the Thunderbolt 225 Ac/150 Dc and the lowest price thus far has been $171.00. Air Gas in Cincinnati sells it for $176.46. I do have a 160 Amp diode and if I bought another 3 it would still be less than the lowest price I have found for the Miller rectifier unit (model number....230777)

Thanks
Tim
__________________
Hey! What do ya'll say we go to Wallys house?!?!?!
Reply With Quote
  #19  
Old 01-14-2017, 01:26 PM
GWIZ's Avatar
GWIZ GWIZ is offline
SFT Historian
 
Join Date: Feb 2006
Location: USA
Posts: 6,333
Default

Quote:
Originally Posted by Rufus View Post
Hi all:
Now, if my current line of thinking is correct, aren't they losing current in the weld output when a bridge rectifier is installed to take the weld current from AC to DC? And if that is the case, isn't the weld current going from 90 amps AC down to maybe 75 amps DC?

I think this might be the case because the Miller Thunderbolt AC 225/DC 160 current drops down to 160 when welding with DC.

Now with my Lincoln Tombstone the current is at 125 on DC. So wouldn't this be the case when someone adds a bridge rectifier to one of these cheap HF 90 amp flux core machines?

Thanks
Tim
Using Diodes you can get a voltage drop from 0.7 to 1.6 volts. I don't think the current loss is going to be that much.


I only used my 230/140 Century welder twice so I cant give you details on welding with it, I have since picked up an HF inverter less weight to move around.

On My Century welder there is a Hi And Low welding Tap.

The Low Tap has a higher voltage output for welding with high voltage rods

It states to use the high tap on sheet metal being it has a lower voltage less chance of burn through.
__________________
*
*
The factory of the future will have only two employees, a man and a dog. The man will be there to feed the dog. The dog will be there to keep the man from touching the equipment. ~Warren G. Bennis
Reply With Quote
  #20  
Old 06-01-2017, 03:01 PM
farmer37 farmer37 is offline
Junior Member
 
Join Date: Jun 2011
Location: dixmont me
Posts: 41
Default

Quote:
Originally Posted by Rufus View Post
Hi all:
I see these people on youtube that will buy the Harbor Freight 90 amp flux core wire welder and convert it to a DC welder. DC because these cheap welders weld with an AC output and the welds are nasty and so as to lay a nice bead they convert these welders to put out DC using a bridge rectifier, resistor and capacitor. Now, if my current line of thinking is correct, aren't they losing current in the weld output when a bridge rectifier is installed to take the weld current from AC to DC? And if that is the case, isn't the weld current going from 90 amps AC down to maybe 75 amps DC? I think this might be the case because the Miller Thunderbolt AC 225/DC 160 current drops down to 160 when welding with DC. Now with my Lincoln Tombstone the current is at 125 on DC. So wouldn't this be the case when someone adds a bridge rectifier to one of these cheap HF 90 amp flux core machines?

Thanks
Tim
Lincoln and miller use small rectifiersto keep costs down.I did a repair on a century welder that claimed 140 amps DC output.A shorted diode was an 85 amp.I put in a new 150 amp diode.I built a DC converter to use on my 150 and 225 amp welders.The welder determines the DC amp output.I used 300 amp diodes .After I used a friends DC welder I built the converter.I had a lot of the parts but it still cost 100 bucks to build the converter.
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Web Search:

All times are GMT -5. The time now is 07:08 AM.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2017, vBulletin Solutions, Inc.