2/14 Update #2, Bushings

I finished up machining the bushings today, and will take all but 1 to be hardened tomorrow.

I decided to harden them even though I bought the Chromoly tubing. This is because if any of them warp because they’re not hard enough, it will be really tough to remedy, especially if it happens on the 3″ thick upper arm. I’m getting it done for $85 at Certified Metal Craft. I’m going to leave one bushing un-hardened so we can compare and see if hardening is necessary. This will be one of the bushings in the Vertical Supports, as it will be easily accessible and visible. If this bushing does deform, we can remove the Vertical Linkages, and remove the bushing by heating up the surrounding material and pressing the bushing out.

For machining the bushings, I simply machined them to exact length +/- .01, and chamfered the edges. I chamfered them so they won’t have sharp edges, and so the pin will go in easier. It took longer than I expected, as I was having trouble getting them centered on the lathe; they were rotating lopsided, so the faces weren’t parallel. I remedied this by watching the tubing closely as I turned the lathe on, and re-seating it in the chuck if it wasn’t centered.

Tip: When cutting, machine the long piece after each cut. This makes lengths much more accurate when measuring to make the next cut, and also makes machining much easier when you are dealing with the 1″ and 1.5″ long bushings, as you will only need to machine one side when it is short.

It was pretty time consuming to make the bushings, but mostly because I’m still unfamiliar with the lathe. I plan on researching the cost of purchased bushings, as this would save a lot of time vs. machining them. For the big bushings, it costs 138$ to make all of them (53 for steel, 85 for hardening), and a few hours of work. This is still relatively cheap, around $16 for the 3″ long big bushings and $8 for the 1.5″ bushings. I’m going to call a bushing manufacturer to get a price tomorrow and I’ll post it.

It appears I’ve left my camera at the shop again. I’ll update this blog tomorrow with footage of the bushings, and photos.

On the grease channels: grandad said my channels are sufficient.


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