PDA

View Full Version : WELDING PROBLEM!! Why don't my welds stay welded?



PaulPb
01-23-2010, 06:58 PM
Hello all;

I got to the point of having my 1st trike welded together (warrior design) 3 wheels rolling. looks really cool!!

So I sat down.....then rolled down the driveway..with 180lbs of me on it....and the welds broke !!!! -

I invested lots of time and money so far and am not about to quit......but what did I do wrong? (or is it the design)

Tell me - since this is my first time using an arc welder.

PaulPb

savarin
01-23-2010, 07:05 PM
difficult to say precisely without a photo.
I would assume you had adhesion but no fusion in the weld.
This is the most common problem at the beginning.
What this means is if your beads looked good then they just lay on the metal without actually melting the two parts together.
If your beads look ugly then you probably only melted the metal in tiny sections and didnt get a continuous joint.
Post some photos so we can see

Radical Brad
01-23-2010, 07:20 PM
Most likely penetration. The frame will bend far before the welds will break if they are done with proper penetration.

Could you post a few photos?

I might be able to suggest some simple gusset or truss arrangements that will help for now.

Brad

PaulPb
01-23-2010, 08:22 PM
This week some time I hope I can get to it - I'm going to clean it up a bit - make sure all my angles are right, weld again - then I'll post some photos - It's a mess now - (or maybe I'll get a few photos tonight......

Thanks PaulPb

jimFPU
01-23-2010, 08:29 PM
Paul, post the photos of the broken welds! This will give us great insight! And you will get great help!

PaulPb
01-23-2010, 08:54 PM
here are a few photos

PaulPb
01-23-2010, 09:00 PM
here are some more

darwin-t
01-23-2010, 10:01 PM
I'm building a Warrior, too and now I'm scared! I tend to grind my welds down and do them over - sometimes repeatedly.

Try to get some closeups - to me (a beginner welder, too) it looks like the beads are too thick - not enough penetration. I look forward to the advice you get - I'll use it to evaluate my welds as well.

savarin
01-23-2010, 10:06 PM
xxxxxxxxxx

savarin
01-23-2010, 10:07 PM
Yep, lack of fusion/penetration.
Your beads are not continuous and dont flow over both sides of the joint.
It also looks as if you have welded over the slag from previous attempts.
There are a lot of variables to keep in your mind at the same time when welding.
The brightness of the molten metal, the brightness of the molten slag (they are 2 different colours and you need to recognise which is which)
The angle of the rod to the work, the amperage your running at, not too much, not too little, the speed you travel.
Your almost there but you need to practice laying even beads on some scrap.
Start at the left side and gently run some straight beads trying to keep the arc an even height from the metal so it burns even and doesnt keep sticking. This is what takes practice.
Once mastered (and it doesnt take long) its never forgotten.
Then do the same and join 2 pieces of scrap with even beads and no burn through.
I always look at it this way - no one would expect to pick up a musical instrument and expect to play a perfect tune.
If you can get some expert instruction it will be a huge help and solve all your problems.

Radical Brad
01-23-2010, 10:25 PM
Can you post a side view of the rear frame? From what I can see, the back end will fail as all the stress is placed on the seat tube? If this is the case, it will fail even if your welds are good.

Brad

PaulPb
01-24-2010, 01:40 AM
Hi Brad;

Yes tomarrow - I'm recharging my batteries for the camera - (I used the tail end of a mtn bike.....instead of what is in the book.)

"I might be able to suggest some simple gusset or truss arrangements that will help for now"

(would something like sheet metal screws and "shelf brackets" like you used for the seat in the book - help strengthen the joints?)

regards; PaulPb

Radical Brad
01-24-2010, 12:44 PM
Once I see the photos, I can suggest something, but most likely you will need some extra tubing to triangulate the rear frame. The way it is now, your entire weight will be carried by only the small seat tube, and I can almost guarantee it will fold on the first real bump.

Even after trussing, side loading around corners might become an issue though, but let's see what I can hack together with photoshop!

Brad

StevefromOH
02-04-2010, 08:03 PM
If you have a gas welder, then try brazing.

Easier to get a good strong joint. Make sure your joints have no space (nice and tight).

Brazing tubing is a better way in my opinion.

Cheezy Rider
02-26-2010, 07:30 PM
What about the extreme amount of heat that you have with brazing though? Alot of chance of distortion and pulling out of alignment. I see the Campbell Hausfeld 110A Arc (stick)welder in the background, is this what you are using? I just bought a Lincoln Mig welder (flux core), and hope that it works good. I too have plans for a Warrior, and would like to have it ready for summer. In the section "Basic Welding" here on this site, they only discuss arc welding (stick). Is this what most builders use? I'm better at stick welding than I ever was at mig welding, but here goes nothing. Just went and bought some scrap tubing from the recycler today to practice on. Also, what type of filler rod are you using? Is it 7018, or what?

darwin-t
02-27-2010, 12:00 AM
Brazing is different than welding with a gas welder.

Brazing is done by heating the steel up and using a brazing rod which flows into the joint. When frame building, you would basically need a smaller tube inside to give the joint mechanical strength.

With welding you actually melt the edges of the steel and add welding rod into the puddle to add metal and strength.

I have done gas welding with my Warrior and it DOES get the entire area red hot. I think with enough tack welds and doing things in the order that Brad suggests, one can do it without alignment problems. One could also weld small sections at a time and letting it cool between welds.

I have mostly been using the gas welder to go over welds I have done with the stick or wire welder to fill in low spots or holes and smooth things up. It's nice for spot welding, too, because you don't have to actually touch anything to do it.

graucho
02-27-2010, 01:52 AM
Hello Paul, excellent info from the guys. Remember now, this is just my opinion and
don't take anything I say here personal. Now that said... Get some scraps and practice, then
practice, then practice some more. As your welding with ark think molten lava. As darwin and savarin said...
melt the edges of the steel and add welding rod into the puddle to add metal.

You need molten steel on both pieces being joined with molten puddling in between. I know its scary
with arc with thin wall but you have to find that "fine line" where you break a puddle on both edges
being joined, then begin to move the molten bead before burning through. Thats where the importance
of practicing comes to play.

As a beginner striking the first arc can be a little scary dealing with all of that amperage so just relax.
Dont move to fast, wait for the molten bead and dont scoot across to fast. Remember that your not
glueing the frame pieces together with a bead, but your melting the 2 pieces together with a bead for the
extra bonus strength.

My last bit of advice is you have to be able to see what your bead is doing. I know you need good eye
protection from the intensity but some of the shields out there are too dark to see the bead your moving.
I may be wrong but it looks to me like your moving a bit too fast and your loosing track of where you are
as your moving across. Remember in the beginning no one says you can't go a half inch stop, and see how
your doing, give it a few wraps with you welding hammer, wire brush then relax and resume.

O' ya.... remember to smile. This is meant to be fun while enjoying valuable shop time. Just my .002 cents.

PaulPb
02-27-2010, 04:01 AM
well since my last reply on this thread I've done alot of work on my adaptation of the warrior design.

My welds are holding now - I've been using different 6013 5/16" rods at high temp (my arc welder only has low and high.)

I had trouble with the front wheel booms it took several tries to get it right (maybe some type of jig or template could be made for those angles, they are very tricky)

It holds my weight - once I got the seat on I could roll down the driveway without any welds breaking.

I just put the steering together tonight - and the v belt pullies - tomarrow the chain......so it's coming together.

I also put together the street fox design (which was alot simpler then the warrior) I don't have all the parts for that one yet so.....

I bought 5/16" 7014 rods also I'm not sure what they are for - maybe someone can explain?

Thanks and best regards to all!!

PS; anyone know where to get cheap shifters?

StevefromOH
02-27-2010, 09:57 AM
What about the extreme amount of heat that you have with brazing though? Alot of chance of distortion and pulling out of alignment. I see the Campbell Hausfeld 110A Arc (stick)welder in the background, is this what you are using? I just bought a Lincoln Mig welder (flux core), and hope that it works good. I too have plans for a Warrior, and would like to have it ready for summer. In the section "Basic Welding" here on this site, they only discuss arc welding (stick). Is this what most builders use? I'm better at stick welding than I ever was at mig welding, but here goes nothing. Just went and bought some scrap tubing from the recycler today to practice on. Also, what type of filler rod are you using? Is it 7018, or what?

Brazing only gets the metal red hot and does not melt the metal. The temperatures of the metal for brazing is around 840 degrees F or slightly higher. Welding gets the metal white hot and is over 5000 to 36,000 degrees F depending on the metal being welded and the amperage required to make the weld. There is actually less chance of distortion with brazing especially with tubing. Now with sheet metal you have a different animal and distortion can be a problem. Body shops sometimes braze if they are good at it but many use mig or tig for body panels. The amperage required for carbon steel thin body panels is very low so temperatures can be kept to 5000 F and the heat can be concentrated because of the low amperages.

I am not saying that mig welding is not a good way to join metal especially for bike building.
I use mig and tig in some situations and those processes give me excellent results.

I did some research when I studied metallurgy and found that a brazed joint is actually stronger than a welded joint in many instances. Stress tests indicated that a brazed joint with a lug withstood bending forces far superior to a welded joint.

Either process is great for bike building. The gas welder is better to have overall though. You can do plumbing with a gas welder. You can bend metal with a gas welder. You can cut steel with a gas welder. You can braze with a gas welder. You can weld with a gas welder. A gas welder does not need to be tethered to an electric line.

Dissimilar metals can also be brazed where they cannot be welded such as brass to steel, steel to iron, iron to brass.

The top end bike frame builders use brazing almost exclusively. A good looking and strong braze is easier to achieve than a good looking weld.

Just wanted to give my 2 cents on the welding vs brazing discussion.