View Full Version : HF spot welders

loose nut
05-16-2009, 02:48 PM
Harbor Fright has there spot welders on sale, two models rated 110 and 220 , although they look identical. They have no visible way to adjust the power settings so it seems it's full power all the time.

The 220 model says it can do 3/16" thick material, doughtful, and there is nothing on the 110 models capacity. Does that mean that if using on on thin steel like 20 gauge it would work or will it just blow a big hole in it.

My needs are for mostly 16 gauge and thinner.

Has anyone used one of these machines.

P.S. found out the 110 model is rated for 1/8" thick.

05-16-2009, 02:56 PM
I bought one a couple of years back for an automotive project. It works OK, spot welders are pretty simple. The documentation that comes with it is pretty worthless but Miller has good documentation for theirs on the miller welds site. Unless you have a lot of welds to do, it is almost easier to drill holes in one piece of the sheet metal and then weld through/grind smooth.

05-16-2009, 03:12 PM
I put a computer-timer and a air cylinder on mine.

It is not "duty" rated at 100%.. read the online pdf. Guesstimate %15..

You can make your own easily.. find a transformer with 15amp primary and outer winding on the secondary.. unwind it.. now take one loop of 2/0 welding cable and replace it. That is all there is to it.

A timer is wonderful to achieve nugget welds of consistent quality. Most of my welds are 250-400 microseconds.. it gets the sheet "redhot" in a instant and melds the metal together.

I have a couple of LARGE transformers from a hyster battery charger that work fine, they are a over-under type winding arrangement. If you were local I'd give you one, but they are too heavy to ship, probably +85lbs

You are after about 1 1/2-2 volts output.. parts must be clean and free of paint.

I have a pdf on building your own spot welder.. plus doing it yourself you can design the arms anyway you want.. if you buy some copper bar you can turn your own tips..
I'll have to find the pdf if you want a copy emailed.. thou the harbor freight spot welders work for LIGHT duty, they heat up and smoke if you try to clicky bang weld like I do..

My HF spot welder has not burned out yet.. want a bargain?? I have gotten it hot a few times.. with the 115 model keep the tips filed back sharp.

05-16-2009, 05:25 PM
The HF spot welder is a copy of the miller hand held spot. I would get the 240 version over the 120 one.

On these spot welders current is limited by the length of the tongs. They are available in 6", 12", and 18". He longer the tongs the less current. Look up the miller manual for their spot and you can get an idea.

05-16-2009, 06:19 PM
I have the 110 volt version as it has been said by Macona. Get the 220 volt if you can power it. And also by David about the duty cycle. I cut grooves the tips so it would work on two round crossed stock.
The units were made in some eastern European country when I bought mine a couple years ago.
And the Miller spot welding guide is a good one to follow, also been said. It won't do 8 hours a day but for spot welds with some time in between. Mine works fine.

05-17-2009, 12:57 AM
I have two of the HF 240v welders and would find it hard to live without them. One I use free hand and the other is setup with an SSR and timer. I made some 22" tongs for a job I just finished and it worked well with 20 and 18ga. welding. This panel is over 50" wide and had to spot weld top hats to it. The top hats are 18ga. and the panel is 20ga. The long tongs were a necessity. There's also a 2 x 2 x 1/8" thick angle at the bottom although this was done with "fender" tongs.


loose nut
05-18-2009, 03:37 PM
I don't need to use it very much so I'm not worried about the duty cycle, just about blowing through thin metal.

Does any one have a drawing or part numbers of timers that will work with this.

05-18-2009, 09:49 PM

If you need help with timing? I got this basic stamp program.. only take several hundred dollars to replicate.. or ..???

Anyways.. timers can be had on grainger.com website for less than $80 that are simple.. KISS principle.. instead of "David Cofer" put a stinking computer on it to really confuse the help...

I think the miller unit had a pneumatic timer on it the last one I worked on.. really old school and simple.. "wheeze" click.

Once you figure out the "clamping pressure, time to weld, clamp time?" the rest is childs play to do perfect spot welds.. till the tips flare out and mess it all up again where it needs tuning..

If you need me to find one model number on grainger I would be glad to look for you, at 3am next time I can't sleep...

05-18-2009, 09:51 PM
I love my HF unit. It's the 220 one. I bought a bunch of spare tips so I could shape some as necessary.

I just manually hold the switch until the weld looks right. Not terribly consistant but has done the few little things I have needed to do.

I'm not an electronic guy, from a design standpoint, and would just be thrilled if someone had a schematic of a time setup they would share. I can build stuff like that but can't design it. :( David???

Such a set-up would be way cool!


Jim Stabe
05-19-2009, 10:37 AM
I'm on my 2nd 220v spot welder. The first one went out in a spray of sparks and smoke which will certainly get your attention since you are holding it in your hands. Can you say "personal protective equipment"?. No problem getting it replaced at the local HF store once I started describing what happened to the manager (a loud voice in front of other customers helps). With a little practice you can make some respectable welds with it. Don't bother with the 110v version, the 220v has a hard time with 16 ga.


loose nut
05-19-2009, 04:48 PM
I picked one up today, on sale $20.00 off, tried a couple of welds on some 16 Ga. plain steel and it worked great. The welds took quite a bit to break. Nice small little divots too.

Didn't think about getting spare tips, does HF sell them or do I have to get them elsewhere. Can't find them in the catalog.

05-19-2009, 06:39 PM
They sell them on line, and they take a while some times coming.
Try and see if the Miller ones will fit I ordered 10 pairs when placed my order. They use to sell them at the stores but they kept stealing the packages. It got so bad they take them off the display models.

05-19-2009, 09:23 PM
The Miller tips won't fit the HF. They're different threads. :mad: But... it's not hard to turn them down and re-thread. Or make your own from chromium-copper. (Alloy 182 @ McMaster-Carr) I bought stock and make my own because of the shapes I need. It's pricey but still cheaper than buying the Miller tips. Unless, of course, you can get Miller tips for less than $7 a pair. The tips will last a long time if you don't burn them.

Forgot to mention: The duty cycle is 50% on both the Miller and HF. Since most sheet metal welds will be less than two seconds, I doubt you'll be setup for the next spot in two seconds. Duty cycle has never been a problem and I use mine a lot.

05-20-2009, 07:21 AM
I saw some nice welding "tongs" made from a set of welding clamps.. Pretty interesting. One side had a piece of white uhmw as a insulator.

I'd like to build a rig to "weld studs" for dent pullers for my rig laying in parts in a box.. that is the same operation, a timed weld.

loose nut
05-20-2009, 10:46 AM
Would ordinary copper work or is it to soft/wrong electrical properties.

05-20-2009, 01:48 PM
I saw some nice welding "tongs" made from a set of welding clamps.. Pretty interesting. One side had a piece of white uhmw as a insulator.

That might work for one or two spots then the UHMW would melt.

I'd like to build a rig to "weld studs" for dent pullers for my rig laying in parts in a box.. that is the same operation, a timed weld.

The HF stud welder is pretty cheap and works good. I made a tip to use it for shrinking too. The darn thing gets heavy after a while though.

Would ordinary copper work or is it to soft/wrong electrical properties.

It would work but wouldn't last very long.

Dumb reply box doesn't like all quote responses so I had to add this line. :rolleyes:

05-20-2009, 04:32 PM
CCW: Well... what the devil is the white plastic if not uhmw? I had one block I silver soldered tattoo needles on, to group them in a tight lil bundle. You had to use something that the solder would not stick to. It's in my kit somewhere. I never sold or got rid of the needle jigs and stuff..

Silver solder is 760degrees or so..

Mostly what I use purchased uhmw for around here is sliders and to take up slop.. it self lubricates under load, under high pressure it liquifies enough to give less friction but does not melt and run out.

05-21-2009, 12:46 AM
I suppose it could have been plastic but the tips and tongs get mighty hot after a few spots. I suspect the white may have been a ceramic button. I've got ceramic molding compound. It looks like plaster of Paris. You just mix it with the activator and pour into a mold. After it hardens, it's baked and becomes hard as rock, er, ah ceramic. Makes great insulators as well as metal molds. I use it for making "die cast" emblems and parts. It good to 2000+ degrees. (I forget the exact rating.)