Welding a bolt to pipe

[LFrosty]

I am in the process of building something loosely based on a DIY go kart.

I'm going to be welding up a couple of these soon - they are the steering joints. The idea is that the bolt on the left is used to mount a wheel, and the bar on the right connects to the steering rack.

I am new to welding so I might be wrong, but I can't help but think that the bolt will be under a huge amount of strain and will simply shear off when travelling over the slightest bump. It also looks quite tricky welding a flat bolt head to a round tube!

I'd like to hear people's opinions on that kind of join. Will the weld be ok, or if there is a better way to achieve the same thing?

The kart will carry 2 people and weigh about 50kg.

More info on the steering component can be found here:
http://www.diygokarts.com/kart-plans/steering-plan-spindles.html

 

[Big Pete]

I've seen worse setups. The bolt head needs to have any zinc plate removed, and some gusset plates to help the tube would be worthwhile. The most likely failure mode is fatigue cracking in the vertical tube, or possibly under the head of the bolt. Proper air filled tyres will be better than solid rubber ones. Probably worth trying to let the weld cool down slowly as well.

 

[LFrosty]

I've seen worse setups. The bolt head needs to have any zinc plate removed, and some gusset plates to help the tube would be worthwhile. The most likely failure mode is fatigue cracking in the vertical tube, or possibly under the head of the bolt. Proper air filled tyres will be better than solid rubber ones. Probably worth trying to let the weld cool down slowly as well.

Great advice thank you. I will be using air inflated tyres so that will hopefully lessen the shock to the bolt. Could you explain a little more about the gusset plates and where you would use them please?

 

[Big Pete]

The gusset plates are triangles of steel sheet (2mm would be fine) that spread the load from the head of the bolt along the length of the tube, rather than concentrating it in the middle of the tube. They spread the load over more steel.

 

[piman]

Hello LFrosty,

on a slightly different tangent, although it is difficult to judge from the picture, the steering arm should not be at right angles to the wheel stub axle. It should have an angle such that an imaginary line from the pivot point along the steering arm will intersect the rear axle centre, this gives the inner wheel more turn than the outer as the inner travels on a smaller radius.

Alec

 

[langy]

Hello LFrosty,

on a slightly different tangent, although it is difficult to judge from the picture, the steering arm should not be at right angles to the wheel stub axle. It should have an angle such that an imaginary line from the pivot point along the steering arm will intersect the rear axle centre, this gives the inner wheel more turn than the outer as the inner travels on a smaller radius.

Alec

Also the bolt that is acting as a kingpin should be at an angle so as a line through it should intersect with the tyre contact patch.
You would do well to google steering geometry before do any further work

 

[LFrosty]

Thanks for your replies so far. I have a very solid understanding of Ackerman angles, caster, KPI and everything else related. I'll be able to take care of all of this this once the build has started.

My primary concern during planning is just the strength of the axle in the first place, but it seems that it will do the job with a bit of modification.

Big Pete thank you for your fabrication suggestions. I'll follow those and see how I get on.

 

[Welderpaul]

Not a bad set up, theres a big 'prep' each side where the bolt head meets the tube, weld it nice and hot and it won't shear off.

Not sure if they are tacks, but they look very cold.