Day 3: now the steering is actually done…

Sorry for the lapse yesterday. Today I am a little behind. Looks like I will have to make a motor mount and seat mount by the end of tomorrow. Yesterday I did most of a steering system, and today I spent a good bit of time fixing it, and then actually finishing it.

The steering system is of a pretty generic go-kart flavor. I started by taking some 1/4″ wall Al channel to make pivots for the front wheels.

front wheel pivot, pre-weld

I was pretty nervous about doing fillet welds at first because it was really hard to start the weld, and then control the heat. But I felt I really needed them on this part for it to be strong enough, and it turned out okay.

front wheel pivot, pre-assembly

The front wheels are 5.5″ scooter wheels. Everything pivots off the steel tube with bushings pressed into each end (I couldn’t find tubing of the right size, so Al sleeves are pressed onto the bushings). The steel tab will connect to the steering rods.

welding the wheel axel bolt to the pivot
wheel pivot at the end of day 2

For the steering column, I decided at first to just have a 5/8″ steel tube pivot directly in a hold in the frame. If you look closely you’ll see that the unfinished nuts have their threads drilled out. The large one will couple to the steering tube, and the other two will hold bushings for the ends of the steering rods. I was too lazy to bore out steel rod and nuts are easier to clamp in a vice anyway.

Notice something wrong about the picture below?

steering column pre-assembly

yea…late night drilling is often off-center I guess. Good thing it only took me like 4 hours to notice. This is what I spend a lot of time correcting today.

that hole is really quite off center, oops

I decided that I wanted to do the extra work to re-center the steering column. The solution I settled on involved boring an on-center hole at a larger diameter (3/4″) and then turn brass bushings for the steering tube to turn in. Because of the previous off-center hole, a good part of the bushing diameter is not supported. I’m not sure how critical this will be, but I’m definitely hoping for the best.

Making the bushings was kind of a pain. Boring solid brass out to 5/8″ takes some time, mostly I found I had to do it in many increments because taking off too much would just result in the bit grabbing, and pulling the chuck out of the tailstock.

incremental drilling for steering bushings

After day 2, I also realized I didn’t do a very good job designing the initial weld joints. If you recall, I initially cut slots into the main struts to fit the cross struts. This left very little material to prevent the end of the struts from bending side to side. In fact, installing the rear axel was a traumatic enough procedure to noticeable bend them. Solution: gussets.

gusset plates, pre-weld

I scrapped two of these before I successfully welded one on. Its a tiny piece so its tricky not to overheat and melt right through it. I found it was easiest to start at a corner where there was already a weld bead. I could heat up the end of that bead and feed it wire until it basically pooled onto the corner of the gusset. With the two chunks of metal now thermally linked, it was much easier to keep from melting the gusset away.

rear gussets

front gussets. I thought it would be a good idea to weld all the way across and reinforce the tubing, since I drilled a large hole into it.

milling the gusset welds flush for steering column bushings

with bushings

The old off-center hold still shows off to the side. Oh well, I’ll just live with it.

Assembled steering

What’s a steering system without a steering wheel! Of course, I needed something sized appropriately to my vehicle.

steering wheel, pre-weld

The central hub is machined on a lathe. The outer ring is 3/8″ rod, bent mostly by hand with the help of a round piece of steel scrap. It was fairly easy to bend and quite gummy to cut – definitely no 6061. The spokes are just scraps of 1/8″ plate.

finished steering wheel

glorious

up ahead, motor mount with tensioner, seat mount, putting sensors in motor, battery packs, some wiring, and maybe a foot rest for some more reasonable leg extension.

2 DAYS LEFT.

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