Today was a productive day in the shop.
I wasn’t happy with how the bushings had pressed into the draw bar yoke. I hadn’t put a big enough chamfer on the holes and the bushings stopped short of seating fully on their flanges. So I used another threaded rod rig and jacked them back out. Filed bigger chamfers and jacked them back in. Much happier.
That allowed us to get a good measurement between the bushings, now that they were fully seated, and that gave us our target dimension to mill the swivel u-joint to final size so that it would fit between the bushings just loosely enough to be easy to couple and uncouple, but still close fitting enough to avoid clacking and slop.

The new milling machine has a few nice upgrade features. In addition to a lot more coolant capacity, it has thru tool coolant, a chip elevator, tool changer, and better software.
Karl also sprang for a couple of very expensive tool indexing add-ons. There’s a jeweled probe that has some very sensitive and accurate measuring circuitry (the white stick like thing sticking down from the spindle). The machine selects the probe, loads it into the spindle, comes over and travels down until the tip of the probe touches the work piece and the machine now knows where the part is within 0.000X (small number) inches. It does this twice, just to be sure.

Next Karl had to reload the the big surfacing cutter into the carousel. In this pic, with the guard door open, you can see a few things more clearly. The cutter is in the spindle at the top, surrounded by the blue and orange coolant nozzles. To the left of that the black bar thing is the tool changer arm. Below the rectangular “lobster tail” segments (which are chip guards for the ways that lift and lower the whole spindle head) you can see my part clamped into the blue vise (or is that vice, lol). I think the red thing on the back of the vise is a fixture to hold adjustable stops, which make changing out parts repeatable. On the back left corner of the table you can see the tool indexer.

Even though it has its own tool holder collet and hadn’t been changed relative to it, and the machine remembers all of that indexing in the library of tools, Karl had the machine calibrate it again. The indexing device has a hard puck mounted on it and the cutter moves over (turning backwards so it’s not trying to cut), and it touches off on the puck to calibrate the tool offset. It does this running to compensate for any cutting edge that might be lower than the others. (Blurry pic because the guard door is now closed.)

Then the coolant starts, the cutting program runs and you pretty much can’t see anything while it’s cutting.

But the part comes out with a super nice finish and fits right the first time (this is just a temporary bolt for setup).

Started building the rig to hoist the camper cabin down out of the loft.
Karl and I had already found where the center of gravity (CG) of the cabin is longitudinally forward/aft as it sits on the build cradle without the galley hatch or side doors… but apparently I didn’t mark it on the cradle or cabin, at least not anywhere that I could discern today. I’m sure I have it documented somewhere, probably even in the blog here, but it would probably take less time to just find it again.
Anyway, the method we used meant tipping the cabin back upright. As we were doing that, when we got it standing on the curb side edge of the floor at the tipping point where it didn’t take any effort to hold it there, I took some quick measurements (height of street side floor edge above the floor and distance it was, plumb, away from the curb side edge along the floor) so that I could calculate the vertical height of the CG. Turned out to be 20.7 inches above the bottom of the floor.
Once I had that we set it back down upright on the cradle. Too heavy for me to do by myself, but not bad with two able body persons. Next, I brought up a piece of 1-1/4 Sch 40 pipe and we put that under the cradle from side to side. We nudged the pipe for and aft until the whole thing balanced evenly on the pipe, which was essentially acting like a fulcrum. Turned out to be about 2-1/2 inches forward of the rear door jamb.
Preparing the cradle for the lifting rig was going to be a lot easier with the camper laying back down on its side, so we laid it back over.
I no longer have ready use of the Inventor modelling software… I still use it almost everyday at work, but haven’t gotten around to setting myself up at home since taking the new job, now almost 4 years ago. Time flies. So rather than using the computer, we just took measurements of the shipping hatch opening (again) and I laid everything out on the floor full scale to calculate the angle that the cabin needs to tip in order to fit down through the hole in the floor. The cabin is narrow enough… we checked that before moving the build up to the loft… but it is just a bit longer than the floor hatch is, so the cabin needs to be tipped, galley end down, in order to fit.
Now, because of the height of the cabin, it actually gets “longer” as you start to tip it… the diagonal from the lower front of the front cabinet bump-out to the tangent point on the radius at the top rear of the galley side wall is longer than the base… so it has to be tipped quite a bit before the relative shortness (from base to roof top) comes into play.
The pick points on the rig will form a triangle between the forward pick point, the aft pick point and the hook on the electric hoist. And this is the most important part, the CG can never be allowed to go outside of the triangle, otherwise one of the pick points would no longer be in tension, and… the bad thing would happen… the cabin would roll upside down, most likely crashing into the edges of the floor hatch.
So that’s the reason I needed to know where the CG is both long and high.
I didn’t actually measure the angle that I need to tip the front end up, but I used a bunch of 3-4-5 triangle measurements, a couple of straight sticks of wood, and a pair of measuring tapes to lay it all out on the floor so that I could see where the CG would be with it tilted, and decided where to put the main lifting bar through the cradle main longitudinal members from there.
If that doesn’t make sense, or you haven’t seen my prior discussion on this subject (or maybe just don’t remember) let me back up a little. The plan is to stick a lifting bar through the 2x6’s that make up the build cradle and pick from that pivot point using a pair of straps running up near the sides of the cabin. The straps will be spread over the roof by a, well, a spreader bar, that with hold the straps from rubbing on the sides of the cabin. From there the straps will angle up to the central hook on the hoist. For the second pick point I’m going to use the two trailer bolt points on the underside of the rear edge of the galley floor; I’ll build a cleat that sticks out from under the back of the floor that I can attach a block and tackle to which will lead up over the oak hinge spar and on up to the hoist hook. By paying out the rope of the block and tackle the galley will tilt down. Once at the desired angle, the rope can be tied off to the cleat and the whole thing will be lowered down through the floor opening.
Provided there is enough head room for the rig to work the way I envision it.
Once I had figured where to put the main lifting bar, I had to move a couple of cleats on the cradle from aft of one of the main cradle xmbrs to in front; then I was able to hole saw through the selected location.
Next I made the main lifting bar. Used the same piece of pipe we used to find the CG. I had to shorten it slightly on the big Marvel vertical band saw, then I cut a couple of short pieces of 1-1/2 Sch 80 pipe that would fit into the clevises Karl has for his straps. We flattened the rings of Sch 80 into ovals so that they would be the same as the smaller 1-1/4 pipe and fit thru the same sawn hole. I lopped off one end from each oval and welded them onto either end of the main pipe making sure to clock them the same on either end.


Here’s a shot of the new CG mark and the pipe fit into the hole in the cradle.

Here you can see how the shackle fits.

Earlier I had been thinking that I would need to reinforce the wood around the pivot hole, but the more I thought about it the more I realized that there was no possible way for the wood to split out in the direction that we would be pulling, so I omitted that. The other thing I thought I might need to do was devise a way to keep the bar from sliding side to side, but with the straps limited by the side walls, and the corners also protected by those heavy cardboard cargo corner protectors that I had been using for finishing churches, I don’t think that will be needed either.
In this wider shot you can see better how the pipe fits thru the cradle longs, and the clevises installed. It’s sticking up a bit more than it will be because the curb side end can’t stick out the way it will when the cabin is upright.

Tomorrow I plan to make the upper spreader and possibly the rear cleat, as well.