welding question

[danlb]

To cut a long story short would a cross drill hole using a grade 8 bolt or just a steel pin strengthen this or weaken it.Money in Africa is always tight so if it works I would be happy.And this is not the USA so we dont sue for bad advise.

To cut a long answer short, a good weld will not be reinforced by pinning the shafts.

[plunger]

To cut a long answer short, a good weld will not be reinforced by pinning the shafts.

And if its a bad weld?

[MattiJ]

I did not trust my memory on this one, so I did some web surfing to confirm that you are better off using a ER70S than stainless. The problem is cracking.

http://www.millerwelds.com/resources/communities/mboard/forum/welding-discussions/6079-mild-steel-w-stainless-filler

Why are you wanting to use stainless?

Dan

Stainless filler is the preferred choice for "difficult to weld mystery metal" like (unknowium)alloy steel shafting, tool steel, high carbon steel, spring steel etc. For extra questionable mystery steels(high carbon etc) preheat to 200...250c.
Esab recommends OK68.82 rod that is similar to american 312.

[danlb]

I don't know.

It seems to me that a pin may weaken the spindle. Could be wrong. But if you have a bad weld that is cracking, the pinned shaft may be better than nothing.

Are you trying to keep the shaft from wobbling within the hole?

Dan

[plunger]

I don't know.

It seems to me that a pin may weaken the spindle. Could be wrong. But if you have a bad weld that is cracking, the pinned shaft may be better than nothing.

Are you trying to keep the shaft from wobbling within the hole?

Dan

No my intention was to make this an interference fit but I couldnt because the shaft was oval.I havent been able to lay a bead 360 degrees around the shaft because the base plate that locates the springs is in the way. Its a light trailer allowed to carry 750kg including itself.

But on another 4x4 forum there are pictures of stub axles machined from solid en8 bar that have snapped right off. They are heavier use 2,5 t but the consensus was that fatique caused this and possibly to rigid a spring setup. Not being a qualified welder there will always be a slight doubt.I just wonder if a cross drilled 6 or 8mm hole in a shaft carrying a load of 750kg would strengthen or weaken it. This would be used for mainly quality roads and 250km at most one way for holidays up the coast ,possibly twice a year.

[MattiJ]

No my intention was to make this an interference fit but I couldnt because the shaft was oval.I havent been able to lay a bead 360 degrees around the shaft because the base plate that locates the springs is in the way. Its a light trailer allowed to carry 750kg including itself.

But on another 4x4 forum there are pictures of stub axles machined from solid en8 bar that have snapped right off. They are heavier use 2,5 t but the consensus was that fatique caused this and possibly to rigid a spring setup. Not being a qualified welder there will always be a slight doubt.I just wonder if a cross drilled 6 or 8mm hole in a shaft carrying a load of 750kg would strengthen or weaken it. This would be used for mainly quality roads and 250km at most one way for holidays up the coast ,possibly twice a year.

EN8 is borderline case when welding as it has enough carbon and manganese to be classified as "poor" weldability.

https://en.wikipedia.org/wiki/Equivalent_carbon_content

For demanding applications this should work:

https://www.twi-global.com/technical-knowledge/faqs/faq-what-is-the-procedure-for-welding-en8-subsequently-known-as-080m40-and-11186-c40e-a-04-carbon-steel-under-high-restraint-/