Tiny anvil knob for forge - video

[Christophe Mineau]

To Christophe Mineau:
Sure you can put it externally. Since the output coil it's directly connected to the cables I guess you want to mount it right before the cables to avoid the soldiering part and stuff, right?

Hi, It's just to give it a try before cutting the wires, if satisfied, I could put it internally just like you, I'm not afraid with the soldiering

[Jon]

Congratulations ArmaBianca Creations - your AC/DC Stick Welder Conversion is the Homemade Tool of the Week!

Clever, useful, and the suggestion for externalizing this modification is a good next step.

Some more good builds from this week:

Drill Press Hole Locating Pin by Frank S
File Organizer by hwmrob
Tapping Methods by GBWM
Spreader Bar by Frank S
Lathe Spider by Dudley Toolwright
Power Tool Speed Controller by Mazay
Drill Press by Kwandotechnic
T-Nuts by Frank S
Air Compressor by Catfish
Tramming Standoffs by Frank S
Improvised Toolmaker's Clamp by Improvised DIY
Mill Head Bench Bracket by mylilmule
Collection of Machine Tools by Dudley Toolwright
Nut Extractor by diy creative crafts
Assorted Luthiery Tools by SculptyWorks
Tailstock Die Holder by winkys workshop
Adjustable Angle Plate by ttmrj

ArmaBianca Creations - we'll be adding your tool entry to our All Homemade Tool of the Week winners post. And, you'll now notice the wrench-on-pedestal award in the awards showcase in your postbit, visible beneath your username:



And, you'll be receiving a $25 online gift card, in your choice of Amazon (US-only), PayPal, or bitcoin. Please PM me your current email address and award choice and I'll get it sent over right away.

Nice work!

[NortonDommi]

Fit a couple of big capacitors across the diode output to smooth ripple also make it switchable - to + polarity plus AC. Reverse polarity is useful and some rods require it.

[tonyfoale]

A word of caution. Using diodes in parallel to increase the current rating does not increase the rating in proportion to the number of diodes.
Diodes are not born equal and when connected in parallel some will do the lion's share of the work and some will just loaf along. So the one doing most work will get overloaded and fail, that will put more load onto the remaining ones and so the one that is now most heavily loaded will fail quickly and the effect will quickly cascade through the whole diode pack.

So to avoid these problems you have two options.
1. Use more diode bridges than you think that you need, I would suggest double. They are cheap so there is no need to skimp on the number.
2. Use diodes with a sufficiently high current rating. In the past these were expensive but now they are not. This would be the preferred solution.

I do not know if you are aware of it, but if you add an Argon bottle and a TIG torch you will have everything that you need for a scratch start TIG welder for steel. You could add a solenoid valve in the gas line for greater operational convenience.
40 or 50 years ago I bought a thyristor controlled DC only welder which I used for TIG welding. It worked well. HF or lift start would have been better but I put up with scratch start. That welder is still my favourite for stick welding

I would second NortonDommi's suggestion to be able to switch polarity. I would disagree with the suggestion to fit capacitors, instead use a choke (inductance) in series if you want to smooth the current more.

[Christophe Mineau]

thanks Tony, that's really valuable information. It also opens perspectives ...

[DIYer]

Thanks ArmaBianca Creations! We've added your DC Welder to our Welding category,
as well as to your builder page: ArmaBianca Creations's Homemade Tools. Your receipt:

DC Welder by ArmaBianca Creations

tags: welder

[nova_robotics]

A word of caution. Using diodes in parallel to increase the current rating does not increase the rating in proportion to the number of diodes.
Diodes are not born equal and when connected in parallel some will do the lion's share of the work and some will just loaf along. So the one doing most work will get overloaded and fail, that will put more load onto the remaining ones and so the one that is now most heavily loaded will fail quickly and the effect will quickly cascade through the whole diode pack.

Absolutely, but it's even worse than that. Silicone diodes have a negative temperature coefficient, so the impedance decreases as the temperature increases. So the second one heats up even a tiny little bit, it'll pull more amps, which will cause it to heat up, which will cause it to pull more amps.... and you get thermal runaway and let the smoke out. MOSFETs don't have the same problem with negative temperature coefficient. They (most, all?) actually have a positive temperature coefficient, so the resistance increases as temperature increases. If diodes did this, when in parallel they would naturally balance themselves out and everything would be great.

So why am I talking about MOSFETs? Because if you reverse bias them, or wire them backwards, you can use the intrinsic or body diode of the MOSFET as a diode, but one with a positive temperature coefficient. Anyway, a potential solution to the problem.

[ArmaBianca Creations]

Congratulations ArmaBianca Creations - your AC/DC Stick Welder Conversion is the Homemade Tool of the Week!

Clever, useful, and the suggestion for externalizing this modification is a good next step.

Some more good builds from this week:

Drill Press Hole Locating Pin by Frank S
File Organizer by hwmrob
Tapping Methods by GBWM
Spreader Bar by Frank S
Lathe Spider by Dudley Toolwright
Power Tool Speed Controller by Mazay
Drill Press by Kwandotechnic
T-Nuts by Frank S
Air Compressor by Catfish
Tramming Standoffs by Frank S
Improvised Toolmaker's Clamp by Improvised DIY
Mill Head Bench Bracket by mylilmule
Collection of Machine Tools by Dudley Toolwright
Nut Extractor by diy creative crafts
Assorted Luthiery Tools by SculptyWorks
Tailstock Die Holder by winkys workshop
Adjustable Angle Plate by ttmrj

ArmaBianca Creations - we'll be adding your tool entry to our All Homemade Tool of the Week winners post. And, you'll now notice the wrench-on-pedestal award in the awards showcase in your postbit, visible beneath your username:



And, you'll be receiving a $25 online gift card, in your choice of Amazon (US-only), PayPal, or bitcoin. Please PM me your current email address and award choice and I'll get it sent over right away.

Nice work!

Thank you so much!!

[ArmaBianca Creations]

NortonDommi:
I totally agree with switching the polarity, however I'm not quite sure if the capacitors will make a relvant difference. Surely more amps would flow and more material would be melt.

tonyfoale:
First, the idea or turning it into a TIG welder is so exciting and no I was not aware of it. Looking back I could have put more diodes, totally agree with the fact that they don't work the same. They can take much more amps then they actually do. Consider that the connecting cables are not too big in size (but not too small either) and they are all the same lenght so that, in theory, they should kinda polarize the whole circuit so that the current will be spread evenly just like with a polarized transistor.

[tonyfoale]

NortonDommi[COLOR=#3e3e3e]:
I totally agree with switching the polarity, however I'm not quite sure if the capacitors will make a relvant difference.

No as I mentioned before, this is not the application for capacitors and there are good reasons why you will see chokes in some welders for smoothing but not capacitors. Let me explain some more, for that we need to understand a bit about the electrical nature of an arc.

An arc has the property that for a given length of arc in a given environment (ambient pressure and temperature) the voltage drop across the arc will be close to constant regardless of the current. So putting a capacitor across the arc achieves nothing because the arc is maintaining a near constant voltage to a greater extent than practical sized and affordable capacitors could hope to. On the other hand there many be ripple on the rectified AC, pulsating DC, current through the arc, the way to smooth the weld current is with the use of a series inductor or choke. This is what we see in many welders.

The DC welder that I bought decades ago, which I used for TIG welding steel as well as stick welding, was fitted with a choke and it makes a big difference, particularly for TIG.