Archive | Bushings RSS for this section

3/25 Update

Busy few days. Workin hard and playing harder.

In the past couple of days, I made a ton of progress.

I fixed the 2 bushing holes that I messed up, one from a bad freeze-fit, and one from a stupid measurement error. The solution was to weld up the hole and re-bore it. A very time consuming fix. Don’t make that mistake!

I also had to torch away parts of the lower arm to get proper clearance for the cylinder and linkage.

The cylinder space wasn’t accurate because I couldn’t find the spec’s for the cylinders overall diameter, so I assumed it would be 5.5″. Turned out it was 6″. Not a big deal to fix- Just had to torch away the excess. I found where to torch by making an aluminum “mock-up” of the cylinder and using that to guide where to torch.

Torching 3″ is very difficult. Unlike 2″, it requires you to pre-heat the metal from the bottom, or the oxy will have a really hard time making a straight cut. I made the mistake of not pre-heating when I torched the holes in the linkage, and that’s why they came out so badly.

Once I torched away the cylinder space, I could weld the cylinder mount. Should’ve taken video of the process, but it was pretty simple. Basically, I flipped the arm vertically, so the attachment wouldn’t fall, and held it perfectly centered using magnets. After I tacked it, I double checked it’s squareness, and gave a solid 1/4″ fillet all the way around. After that, I ground away any weld material that would block the cylinder. See the photo in the gallery below.

For some reason, the lower arm was interfering with the linkage. I’m still not sure why the linkage space wasn’t right. In the design, I left 1/4″ clearance for it, because I knew there would likely be small measurement errors, and that the lower-arm torching wouldn’t be perfectly accurate. I need to go back and double check all my measurements on the linkage, and the CAD file I sent for torching the lower arm. It could have been as simple as the fact that the torching is only guaranteed by 1/4″ by the metal supplier.

Either way, I torched away the excess, and now it will work.

I also freeze fit the remaining bushings for the hole’s I’ve bored. I will need to do one more batch of freeze fitting when I’ve completed the upper arm. Here’s a vid explaining the pre-heating; you want to get the steel hot enough so it starts changing colors. Didn’t get any shots of putting the bushing in cause my camera ran out of juice.

The final freeze fit got stuck midway thru. I was going to take it to the press to push it in, but the guys volunteered to help me. My little girl muscles weren’t enough to hammer it further in, but Mike’s most certainly were! That’s one heavy hammer.

After the freeze fits, I had to grind down whatever parts of the bushing were sticking out of the material; some of the material was thinner than specified, so the bushings were sticking out. This could cause a problem because when the pins are in, they will need to be clamping down on the entire piece, not just the bushing. If it’s just clamping on the bushing, the metal could end up slipping out further on the bushing, causing the arms to get out of parallel. This would destroy clearance accuracy with the blades, and result in either sloppier cuts, or broken blades.


3/21 update

I was on fire today! I wish it was figurative, for if anything, I was the opposite of “on fire” in terms of my working speed today. But alas, it was literal. Its been a while since that happened. Its kinda exciting every now and then. It burnt the hose too, on the torch.

So, first thing today, I was gonna freeze fit the bushings. I did one yesterday with just normal ice, and it worked fine, I just had to use the press to push the bushing in. I figured I didn’t need to buy dry-ice, since it worked. I was wrong. I did one successfully today, using the press. The second one wouldn’t go all the way thru. I flipped the piece over and discovered horrible galling, and material ┬ádisplaced! After talking to the guys, I found that was because the bushing must have gone in sideways, and the press kept pushing it in , so it scraped away excess material. They said this happens to the best of em now and then, that they’ve all done it. See vids.

Seems like there’s really not any way to prevent it if you’re using a press to put them in. You can be more careful that it doesn’t get cocked, but it’s really hard to tell when you’re doing it.

My solution is simply to use dry ice. It worked really well before, and it’s relatively cheap (~$6.50 for 5lb). Best part is that it will make the bushings go in with just a hammer. Or even with your hand.

I shipped the welder to OSE today. It took up about 2.5 hours to get it shipped. Jimmy taught me how to use the packing machine. I forget what it’s called, it uses metal straps and crimpers. I also shipped the cylinder and a gas cut-off saw that Marcin bought from my uncle. See the pics in the gallery below.

I began on the cylinder mount. I did things in an odd order because it was so small. See video below. First I torched the radius, but didn’t torch it off. This is so I could have a center mark to torch from. Then I mag-drilled out the mount hole. After that, I torched it into a piece slightly bigger than the mount. This was so I would have something to clamp it to while I machined it down. Then I machined it to the proper thickness, and bored the hole to exact diameter. After that, I finally torched to proper size. See photos.

2/23 Update

Freeze fit bushings in vertical linkages. Still need to finish the second pair. I am slow and frustrated with my slowness and clumsiness.

The first freeze fit

2/22 Update

Finally got the big holes figured out. Jimmy did the first hole in the vertical linkages using the motorized circle cutter, and taught me to use it. I wasn’t successful the first time, I need to go back and fix it tomorrow. The second time I was successful. See the photos below. I plan on finishing them completely tomorrow.

I also bored out the hole that Jimmy torched. It took a long time, about an hour. However, other things can be done while boring them, since our machine has an autofeed. I plan on working on the sketchup model tomorrow while boring the other holes.

I’m also picking up some dry-ice to do some freeze fitting tomorrow. Once the bushings are frozen, I will know what the final bore should be; It needs to be just bigger than the OD of the frozen bushings.

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.