Thread: Welding help and advice needed please.

If I were you I'd be practicing LOTS of welding things together that may resemble your project. Then I'd be using a sledge hammer to test my welds for strength.
They say 6010 or 6011 is a good rod as it penetrates deeply and the slag freezes quickly.
If you're using 4.6mm tube I don't think there would be a problem going for a 3.2mm rod, if your welder has the capability.

Remember, a poor weld in this situation could mean someone dies.

Tom.

I luckilly have a 3m piece of pipe to practice with (only need 1.2m) and figured it was worth having a go at in the first instance and if not will get it done. I've seen some pretty weak home welding used on some very dodgy homemade trailers that still takes a fair bit of strain but I want this to be strong. I will be doing a lot of practice first.

Thankfully (or could be said to be unfortunately depending on how you look at it) the onus is on the builder/repairer/restorer to ensure it is safe as there is not currently a need for any engineering, safety inspections or certification in Qld for a homemade trailer. You can even register it and obtain a VIN without anyone from transport even seeing it once (self assessment) which is a bit dodgy - theoretically if you knew your measurements you could register it before it is even built! But that is going off topic a bit.

I did even consider a high tensile threaded rod up the centre of the axle, effectively bolting the flanges to the tube as well, to provice some additional safety and strength, this will only be a 750kg GVM trailer so only light duty, not offroad or anything like that, so as long as the axle can handle that weight it will be fine.

Definitely worth checking the penetration on some test pieces first.

I have done some beautiful looking welds that had low penetration and later came apart..... Luckily nothing critical, but I was surprised because from 'the outside' they looked very nice

Also note that if you want to bolt anything onto the flange, (and I am presuming you will bolt on stub axles) you will need to machine the faces to ensure that they are flat and parallel to each other. If you need help with either welding or machining give me a yell.

Cheers, Mick.

Originally Posted by Killer

Also note that if you want to bolt anything onto the flange, (and I am presuming you will bolt on stub axles) you will need to machine the faces to ensure that they are flat and parallel to each other. If you need help with either welding or machining give me a yell.

Cheers, Mick.

The flanges I'm using are ex diff flanges and so the surfaces are flat already, assuming I cut my pipe straight which is the plan, they should be parallel and level prior to welding, hopefully since the welds will be on the inner side of the flange I shouldn't need to machine it down. The plan is to tack it and check it, make any level adjustments so it is right then weld it. I may yet take you up on the offer of help if I can't work it out. The closest I've come to machining is using my drill in the vice as a mini lathe. Works well for small stuff but not great for an axle!

How do you ensure good penetration? Is it more the speed and technique, the quality of the welder and rods or how hard you push? Any tips?

Set it up and get it all square then tack weld it.
Then take it to an Engineering Business and get them to run over it with the Mig. Then you just have to machine the faces to get them perpendicular to the axle and parrallel to each other.
It will give you peace of mind!

Cheers, Mick.

Sorry, excuse my lack of knowledge, but if the pipe is cut square with ends perpendicular, and the flanges are welded on after being squared and are set in the correct position, wouldn't it be square enough at that point? Is there a reason why it would need to be machined? It would be too thick to warp from the heat of welding.

nothing is too thick to not warp or move when welded.. if welded properly

you want to do it properly, get them machined afterwards...