Today I completed the “long cross-country solo” part of the the private pilot requirements. I made a big triangle over the middle of the state with legs of 104, 61, and 56 nautical miles. Along the way I spoke with approach control of two different class C airports, everything went great.
This afternoon I completed the controlled field solo take-off and landing requirements; 3 take off and landings to a full stop. There’s plenty left to learn but altogether this went fairly smoothly; some of the intimidation factor is now gone and that will be a big help for future flights in controlled airspace. Here’s an old photo of the airport (guess which) where I did this:
I may have only a handful of flights left prior to the checkride: a night cross country (dual), a long solo cross-country, some more practice, and then the mock checkride.
The weather is warming up and I’m anxious to start driving the bus again. Since the last trip prior to winter ended with stalling I put the bus up on ramps and investigated the problem. Based on the behavior I had suspected fueling problems. I checked the fuel pump and it was OK (though it’s 30years old so I’ll likely replace soon anyways), and also replaced the fuel filter. The old fuel filter was full of rust particles but it wasn’t really restricting the flow. A clue came about during replacement of the filter when I forgot to crimp the fuel hose upstream of the filter. Normally this would mean a shower of gasoline but there were only a few drips, indicating a clog upstream of the filter. I pulled the hose fitting off of the bottom of the tank and found it almost completely clogged. I had cleaned the tank when I had it out for repainting but it doesn’t take much to cause a clog. Now that it’s being driven the gas is sloshing and continuing to clean it out further. I’d expect the worst of the gunk has passed through by now but I’ll have to check this fitting periodically.
The first night flight was tonight, I arrived a little early and had to wait for sunset. Things looked very different but overall it wasn’t that bad.
After cancelling many flights due to weather I finally completed my first cross-country solo this weekend. 56NM from wheels up to touchdown. 4500FT on the way there, 37min. 3500FT on the way back and only 25min, top ground speed was just short of 150MPH.
Next up is night flying, followed by a night cross-country, and then it’s just some practice and review prior to the check-ride. If the end of winter brings better weekend weather I should be able to finish soon.
Tonight I got the machine fully assembled and working with all axes (and the spindle) at once. This greatly improves image plotting since the pen can be lifted. I just need to mount the spoil board and I should be able to begin cutting tests.
It’s been a while since I’ve updated, and I’ve gotten a lot done during this time. I modified the gantry motor plate (one of them at least) to include a spring tensioner and also added some diagonal braces to the gantry columns; the gantry now runs even smoother and with little or no backlash. I then added the Y axis guides, fabricated the Y axis motor carrier and Y rack support. Once I got all the Y parts together I was able, for the first time, to test coordinated motion between axes by clamping a pen to the Y axis. The results of this testing were great. It drew very accurately with the pen, the drawing path even occasionally required overlapping the same pen line later in the program; it was able to follow the existing lines exactly. The only thing it couldn’t do was lift the pen, since the Z axis wasn’t installed…
…So after I eventually finished playing with plotting images I began work on the Z axis. The biggest challenge with this was attachment of the spindle mount; the spindle mount is one of the few metal things (other than the motors/guides/racks) that I didn’t fabricate from scratch; despite this I still needed to do some fairly extensive machining/modification to get it attached to the Z extrusion in a very secure but still adjustable way. With the spindle mounted to the Z extrusion the remainder of the work was just some minor drilling, tapping, and cutting. The Z rack is a lot longer than it needs to be for the amount of travel Z has; it was the last rack section to get cut so the extra length is just the leftover/spare, it fits on the extrusion so no sense cutting it off.
Sometime during initial gantry testing I fried the Z axis motor driver on the smoothieboard when moving the gantry by hand with the drivers off. Z wasn’t even connected during this but my guess is the spinning gantry motors fed back through their drivers onto the supply bus; Z happened to be the weakest and it fried with a snap & flash. Because of this I was actually testing the Z axis with the Y driver. I have an external stepper driver on the way and once it arrives I should be able to move all axes at once and really see what it’s capable of. Next Steps:
#1 – Finish electrical enclosure fabrication
#2 – Modify other gantry motor plate to include spring tensioner
#3 – Final fabrication of cable management, cosmetic covers, etc.
#4 – Disassemble, body work, prime, paint
#5 – Final reassembly & wiring
Lots of fabrication work over the past week including the motor brackets, columns, and home switch trigger. The gantry axis (still debating whether to call this X or Y) guide rails as well as many other parts arrived Friday and were mounted to the machine base. The machine base also got a coat of body filler (the pink spots in the photos) and sanding in anticipation of paint.
With everything fabricated and assembled, I was able to temporarily wire the system and run the first motion tests of the gantry. Overall I was extremely impressed, the homing switch worked and both sides stayed perfectly in-sync. The gantry achieved the same 1200IPM I had seen in the rack testing. I somehow managed to build it with tight enough tolerances that the rack doesn’t bind and isn’t overly loose over the full travel range, but there are still some noticeable differences in some spots. Right now the mesh is only adjustable with the play in the motor mount screws. One improvement I’ve already got on the drawing board (screenshot below) is to add a spring tensioner system to keep the rack mesh constant across the entire travel. There was enough room where I won’t have to re-build anything to do this, it almost looks like I planned to have it from the start.
Also, in aviation news, this weekend I passed the phase check to be able to fly solo cross-country. I’ve been able to fly solo for a while but only within the local airport area; this now means I can fly solo between airports and continue practicing cross-country flying.
This weekend I did more work on the CNC machine base:
– Power inlet, power switch, USB port, and E-Stop holes were all drilled & filed to the correct shapes.
– Rack support rails were added to the frame edges and end-caps added to the frame front and gantry ends.
– Flame straightened the frame to relieve welding stress/distortion. It was my first time trying this so I wasn’t sure about it at first, but it worked great. I put a straightedge on the frame and found which side was convex; then heated that side in several places until it was just red hot. After it cooled the straight edge showed a much smaller gap in the middle on the concave side; I repeated this until the frame was flat in all directions.
– Flame straightening got the frame flat overall, but there were still a few high-spots. These were ground down with a flap wheel until no gaps existed with the straight-edge and the entire frame was perfectly flat.
– Machined holes into the gantry drive racks. The clearance between rack edge and the inside edge of the rack teeth was extremely close. I bought some extra room by grinding down the outside diameter of the bolts some, but it was still very close. For the most part I was able to get the holes centered exactly in in this small space, but there were a few holes that created a notch in the outside edge of the rack; luckily none of the holes interfered with the rack teeth. The other racks will be easier since they’ll be mounted from the back side with partial depth holes drilled/tapped into the back.
There’s still some fabrication work left to do, but several critical parts (Guides, spindle, etc.) are all on a slow boat from various far east locales. They’ll become the limiting factor, so I’m taking it slow and making sure everything is done as well as it can be.
The metal has arrived and over the last few nights I’ve begun fabrication of the machine. For the electronics enclosure I’m re-purposing the original crumpled hood that came with the golf restoration project. After removing the inner support, the outer hood skin was a reasonably flat piece of sheet metal. (That does also make this machine part VW, but it wasn’t intentional) I don’t have a big press brake for accurate bends, so the box that resulted is a little wonky, but its nothing that can’t be salvaged with some body filler and sanding.
I’m moving fairly slowly with the machine base, making sure everything is as square, flat, and true to the design as my ability to measure, and so far it’s looking really good. I also have the gantry mostly fabricated, which consists of two pieces of angle iron welded edge-to-edge, forming a channel.
– Fabricate gantry columns
– Fabricate motor plates
– Fabricate Z axis mounting plate
– Fabricate electrical enclosure lid & connect to base w/ piano hinge
– Machine base flatness check and hand scraping of guide mounting ways
– Drill & tap holes (dozens of them) in the machine base and racks for mounting the racks and guides
– Disassemble, Paint, & Reassemble