Skip to Content.
Sympa Menu

homestead - [Homestead] Lawnmower welder repost

homestead AT lists.ibiblio.org

Subject: Homestead mailing list

List archive

Chronological Thread  
  • From: tvoivozhd <tvoivozd AT infionline.net>
  • To: homestead AT lists.ibiblio.org
  • Subject: [Homestead] Lawnmower welder repost
  • Date: Fri, 14 Jan 2005 15:36:35 -0500

Yeah,, I posted it before, but your short term memory is shot. To do welding you really need a portable welder---you can install a big welder-generator in your pickup truck in place of the alternator it came with, but there are a huge number of cheap lawnmowers around to be had for little, or the cost of picking them up---so it can be a small home business.


[Homestead] Lawnmower generator/welders

*Tvoivozhd* tvoivozd at infionline.net <mailto:homestead%40lists.ibiblio.org?Subject=%5BHomestead%5D%20Lawnmower%20generator/welders&In-Reply-To=>
/Fri Sep 10 23:53:03 EDT 2004/

* Previous message: [Homestead] now where did that job go ?

<https://lists.ibiblio.org/sympa/arc/homestead/2004-September/000396.html>
* Next message: [Homestead] Home business, miscellaneous homemade
tools

<https://lists.ibiblio.org/sympa/arc/homestead/2004-September/000392.html>
* *Messages sorted by:* [ date ]

<https://lists.ibiblio.org/sympa/arc/homestead/2004-September/date.html#390>
[ thread ]

<https://lists.ibiblio.org/sympa/arc/homestead/2004-September/thread.html#390>
[ subject ]

<https://lists.ibiblio.org/sympa/arc/homestead/2004-September/subject.html#390>
[ author ]

<https://lists.ibiblio.org/sympa/arc/homestead/2004-September/author.html#390>


------------------------------------------------------------------------

This is supplementary to previous postings I made on engine-generator welders (not sure they made it into the Homestead Archives)

http://www.huv.com/jon/jeep/Welder/portable-welder.html (Jon's Jeep website, schematic, materials list to make a rotary lawnmower into a welder, also refer to the old Mother Earth archives which had an article doing the same thing.)

http://theepicenter.com/tow02077.html (epicenter horizontal shaft engine generator, they also sell a metal plate upon which to mount both engine and generator, easier than trying to fabricate your own.
See the easier-to-come by vertical shaft engine option, and the bracket to direct-couple (no belts) engine and generator---it's not a quill-mount where a tapered shaft fits into a tapered hole, uses something like a Lord coupling to couple two, hopefully same-diameter shafts.).

Back in the mid 1950's I used 7/8 inch tempered masonite as a base for one of my engine-generator models---more rigid than plywood and a lot more rigid than cast-aluminum. Also used a Lord coupling which didn't pound out under two-stroke power impulses as some other brands did.

http://www.qsl.net/ns8o/Induction_Generator.html (some info on induction motors as generators---for resistance loads, don't use them to start motor loads)

The above are intended for stick-welders, one battery is really insufficient, as is 12 volts---better to put two batteries in series to the welder cables, and charge the batteries via 12-volt parallel hookup.

And you should buy the Homepower archive CD's---Hp #77 describes a pulsing desulfator circuit that is the only way to restore a battery so dead and sulfated it has reversed polarity.

And you would get better performance from a wire-feed than from welding rods. Two 12-volt batteries in series will suffice for most wire-feed work



Using a wire-feed welder will produce better welds. You can easily modify a "wal-mart" wire-feed welder to run on 24v DC.

Use a heavy-current parallel mosfet bank in series with the high-power inductor on the positive side (electrode).

The mosfets can be wired with all common leads in parallel. The current-handling capability of the bank is the sum of all the mosfet's current ratings. It can be built from almost any kind of mosfet as long as you have enough total current handling capability and you have plenty of heat-sinking capability.

Place a HEAVY CURRENT rectifier in series between the mosfet bank and the inductor. Place another HEAVY CURRENT rectifier in REVERSE BIAS mode between the GROUND and mosfet side of the inductor.

Drive the mosfet bank's common gate lead with a pulse-width modulator built from two 555 timer IC's.

One 555 is in ASTABLE mode, set for a 50% duty-cycle (important), set to the harmonic frequency of the heavy inductor. It's output trigger's the second 555 timer chip. This frequency is adjusted ONCE and then FIXED in position.

The second 555 is in MONOSTABLE mode and it's output pulse width should be adjustable from 1% to 100% of the FIRST 555's output pulse-width. This output goes to the mosfet bank gate lead. This 555's pulse width is your WELD-POWER adjustment. Narrowing the pulse-width reduces the amount of time the mosfet bank in on.

Here's what happens, in termes of "positive going" current flow. Don't split hairs.

This is ONE complete cycle.

1. The mosfet bank turns on, allowing current to flow through the rectifer, through the inductor and then through the electrode and workpiece and back to ground.
2. The mosfet bank shuts off. The inductor's field collapses, releasing it's EMF as a second current pulse that goes through the electrode and workpiece. This field collapse pulse is routed through the REVERSE BIAS rectifier.

This is the MOST EFFICIENT way to drive your wire-feed welder from a pure DC source.


------------------------------------------------------------------------

* Previous message: [Homestead] now where did that job go ?

<https://lists.ibiblio.org/sympa/arc/homestead/2004-September/000396.html>
* Next message: [Homestead] Home business, miscellaneous homemade
tools

<https://lists.ibiblio.org/sympa/arc/homestead/2004-September/000392.html>
* *Messages sorted by:* [ date ]

<https://lists.ibiblio.org/sympa/arc/homestead/2004-September/date.html#390>
[ thread ]

<https://lists.ibiblio.org/sympa/arc/homestead/2004-September/thread.html#390>
[ subject ]

<https://lists.ibiblio.org/sympa/arc/homestead/2004-September/subject.html#390>
[ author ]

<https://lists.ibiblio.org/sympa/arc/homestead/2004-September/author.html#390>


------------------------------------------------------------------------
More information about the Homestead mailing list <http://lists.ibiblio.org/mailman/listinfo/homestead>





  • [Homestead] Lawnmower welder repost, tvoivozhd, 01/14/2005

Archive powered by MHonArc 2.6.24.

Top of Page