forge welding help?

[Cota]

Hey Guys. 

 

I recently got a new forge and its a gas forge using LP gas and i really would like to do some forge welding or pattern welding. but whenever i heat my steal up and try and weld it all it does is compress it but not like it should be. it continues to have seems and wont just go into a single billet after several hours of doing this i still could never get it to go into a single billet. so i was thinking maybe I'm not heating it hot enough. I typically run at 16 PSI and let it warm up for 15-20 minutes until i put my steel in, what am i doing wrong that wont allow a forge weld? what should I be doing to obtain forge welding temperatures?

[jmccustomknives]

First question, what are you trying to forge weld?  Start with a couple of mild steel rods. This will help you with determining the proper temp that forge welding takes place at.  Are you scaling up?  Using the proper flux?  Tons of questions and a million things that can go wrong.  Look for the stickies, theres lots of info covering this topic.

[SoCal Dave]

First, one or two burner forge.  You stated it was new.  Who made the forge?  A few pictures of your forge would help.  As JMC indicated, it could be a few things that cause you to not reach welding heat.  Have you been successful in other gas forges welding or pattern welding?  I think it is difficult to forge or pattern weld in a gas forge without a blower.  Are you able to measure the temp of your forge after 20 min. of heating?  That might tell you a lot.  Last, you might be able to pump up your temp by coating the inside of your forge with ITC100 or something similar.  Good luck.     

[Frosty]

There are too many variables to consider to get a meaningful answer to such a detail lacking question. For a start, how hot is your forge? Is it a reducing fire? What are you welding? What flux are you using? Are you cleaning the joins thoroughly?

 

On and on, the above are pretty basic but there's more and different forges and ambient conditions change things considerably. You certainly don't need 20 minutes to bring steel to welding temp in my forge and if I have it turned up it'll melt before that. And there are plenty of forges  hotter than mine and way more cooler. by ambient conditions things like ambient temperature makes a serious difference, mine isn't so hot when it' -20f but is a screaming slice of the sun's surface at 70f. Elevation is a biggy too, 6,000' elevation means plenty. As does humidity, the more the harder the burner has to work to heat it up.

 

On the up side Iforge has a HUGE gas forge section. Plenty of reading there, bring snacks and something to drink. A note pad is a good idea too.

 

Frosty The Lucky.

[RogueRugger]

I have some small projects (e.g. fireplace poker end or maybe a basket on the handle) where I'd like to try my hand at forge welding using the gas forge. (A relatively new Whisper Daddy #2, three burner, doors at both ends.)

 

I've done a hand-full of successful welds using a coal forge, However,  I've gotten the general feeling that a few things are a bit different with the gas forge. In particular the type of flux used due to the possible damage to the forge lining from traditional fluxes (borax anti borax).  The iForge forums are so extensive (many thanks to all for that!) that I was certain I'd find something related to this. Unfortunately, I've come up empty handed. 

 

If there is an existing discussion here or elsewhere, would someone point me that direction? If not, I'm open to any/all advice.  

 

...Dave

[RogueRugger]

Okay, it wasn't right after I hit return but almost ... obviously there are a number of discussions outside the gas forge forum that focus on fluxes such as: 

 

This made me realize I didn't ask the question very clearly:

 

Do I need some type of extra protection for the bottom of my forge? 

[SJS]

NC makes a welding plate, which is just a half thickness hard fire brick, as a sacrificial plate to protect the floor from flux. Any inswool that is exposed inside the forge that comes in contact with the flux will vaporize, so don't be sloppy with the flux. When your in a coal forge extra flux just makes more clinker in the bottom, but it is hard on a gasser, especially if it isn't designed as a forge for welding. Bubble Alumina castable will be about the best flux resistant coating for a forge floor, Satinite, and ITC100 provide a bit of protection, but don't hold up very long. The newer NC forges are designed with a hard floor, which last better than the old style lining. BUT still use only enough to get the job done, cause it will leave a black pudding in the bottom of the forge and it will creep up whatever you lie in it. Some guys like to use kitty litter in the floor to grab some of that slag and flux, then you can clean out the floor and replace it to have a clean forge to work in... Hope that helps and others chime in with other ideas...

[Rich Hale]

Forge welding has been cussed and discussed a lot in the forums...I think if you prowl around the blacksmithing section you will have more than you need!

[781]

For the right temp point a 3/16 bar heat to same color as what U plan to weld touch with point U should feel them weld together that is the temp.

[Frosty]

You can lay a piece of stainless steel in the bottom to shield it from flux.

 

As always only use enough flux to do the job, it isn't glue after all, there's no reason for it to be dripping off the work, just coat it.

 

Frosty The Lucky.

[jmhlsy]

Frosty, does one type of stainless work better for the floor liner?

[RogueRugger]

Thanks to all for the suggestions. There's lots of cautions out there, but I had not realized it was quite this bad. The forge is new enough to have the hard floor and I hadn't seen any discussion about how that held up to flux.  I may just order the plate (and flux) from NC but I was trying to return a favor and wanted to have something made this weekend.  My coal forge is tucked away in storage so I may just try forging it clean/dry first. Kitty litter? Never would have thought of that; I've used it to clean up garage spills before so it makes sense I suppose. Whoever tried that first was certainly thinking outside the box.

[Frosty]

Frosty, does one type of stainless work better for the floor liner?

 

That I don't know, I've never tried it. However I assume it isn't important so long as it keeps the molten flux off the refractory. I believe SS is better than plain steel because it won't weld itself to your project piece. It's a trick I heard about from bladesmiths some years ago. I just change out the split fire brick floor in my forge when it gets eroded enough, I designed it to be easy.

 

Frosty The Lucky.

[Chinobi]

The blacksmithing school I frequent recently bought some new chili forges and they had the same discussion about forge liners for welding. SS plates were the first thought but ultimately they went with kiln shelving cut to fit. They can be slid in and out at will and are easy to replace if they get too damaged. The floor of the forge is pretty tough by itself but it requires some extra effort to get in there and change if the flux build up becomes a problem or if it eventually gets eaten away. It's good to be able to take it out when not welding because it gets all over everything!

[danguite]

What kinds of PSI are you guys using to get to welding heat?  I'm using a Diamondback and I run it around 10psi and I don't think it would get a piece up to that kind of temperature.  I know I have definitely not burned any steel yet, which I'd like to do just to prove to myself that it will get that hot.

[Dodge]

What kinds of PSI are you guys using to get to welding heat?  I'm using a Diamondback and I run it around 10psi and I don't think it would get a piece up to that kind of temperature.  I know I have definitely not burned any steel yet, which I'd like to do just to prove to myself that it will get that hot.

 

That's like asking "what kind of gas mileage does your car get?" Depends on your forge. I have a forced air forge that will weld at less than 5 psi. However, my naturally aspirated forge has to be cranked up to 15 psi or higher. Generally, 5 psi is low for most NA forges I have used. Try turning it up.

[ThomasPowers]

Not to mention the fact that most gauges are off---sometimes substantially.  Not to be surprised by the way most of us tend to bang them around.  I have been thinking of building a "travel carrier" for my regulator to protect it from the rigors of the pickup bed loaded with blacksmithing stuff.

 

When was the last time you had your gauge calibrated?  (why I tune by eye and ear.)

[Frosty]

A gauge is a good thing but not as a number thing, it's good for consistency so you don't have to do a full tune routine every time you change settings.

 

Do you know what color to weld at? That's depending on all the other variables of course, ambient temp, humidity, ambient light level, etc. And THAT'S where the gauge comes in, when you find the "right" temp look at the gauge and remember the setting.  A gauge helps find the temp too, by limiting your changes to reasonable amounts and direction. When looking for something like the right forge temp only change one thing at a time and only by a small amount in one direction. If you make BIG changes, say 10psi you'll go from too cool to melting the liner out of your forge so you have to go back down and if you change it too much you're back where you started. You end up YoYoing from one extreme to another.

 

There are two basic techniques, small increments, say 2psi at a time til you hit the number.

 

Then there's the split the difference method, start at too cool and crank it 29psi. (to choose a number for the purposes of illustration) If it doesn't melt the liner crank it another 10psi and so on till it does melt the liner or whatever indicator you use to judge WAY TOO HOT! Then split the difference between too cool and too hot. If it's too cool then split the difference between that and too hot. If it's still too hot split the difference between that and too cool. Yeah sure, you can call it the split the difference method or the YoYo method, it's a matter of controlled changes.

 

Once you get to know your NA burners you'll know the temp by it's roar. Your eyes, ears, and sense of feel are the REAL controls you have in the craft but you have to train them.

 

Frosty The Lucky.

[Chinobi]

that's in essence a binary search frosty :) except instead of boring numbers and code you get to use FLAMES!

[danguite]

Tested the gauge, looks good. I've never cranked it above 10psi, so I'll search for the perfect number next time I'm out there.