Category: Machining / Making

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Engine progress

It’s been a while since I posted an update, but it’s not like anyone is following this anyway. 🙂 The engine is out, and on the engine stand. I ended up buying a new hoist from Harbor Freight on sale. Getting the engine pulled was relatively easy, especially once we figured out there are bolts holding the flex plate to the torque converter.

The cam and lifters are junk. Lifters are worn completely flat, so they’ve got to go — this was expected. Plus, a new cam should really wake the engine up anyway. No surprises there. Timing chain isn’t too badly worn from what I can see, but that doesn’t matter either since it’s getting replaced.

The heads are off and look about as you’d expect for a 93K-plus mile engine. In my humble opinion, the valves are probably not worth saving. There are grooves worn in the ends. I’m going to look for some GT40 or GT40P heads locally, since they breathe much better anyway. Slightly larger combustion chambers, but not enough to really hurt performance — especially with a new cam that can more than make up for it.

Pistons and bores look great. Cylinder bore wear is .003 or less, except for #5. That one is more like .006, with about .004 taper. Bore, or hone? I don’t know yet. Honing would save several hundred dollars on the cost of the rebuild. The machine shop wants around $300 for a bore & hone. Add to that a couple hundred for new pistons. If I can just hone, then I can re-ring with new moly rings and save close to $500. I’ll do some more measuring and get some expert advice before making a decision. I’m not building a race engine here, so there’s really no need to sink thousands into it.

All of the main and cam bearings look good, no scoring or signs of uneven (tapered) wear. The crank measures within about .001 of spec, so no work needed there assuming it’s not bent – and no reason to suspect it is.

All in all, it looks to be in better shape than I anticipated. It was definitely time for an overhaul, though. I’m sure the valves weren’t opening fully. Given the wear on the lifters and valve stems, I suspect the cam lobes are worn a bit as well. Cylinder walls had no crosshatch left, and there were signs of a little surface rust from sitting for a few years. I think it will benefit greatly from a slightly hotter street cam, better heads, a 4-barrel, and new rings on freshly honed cylinder walls.

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New gadget testing

Along with load of keyer circuit board delivered today were some prototypes I had ordered.  I’m working on three different projects for the plane.

  1. Bluetooth stereo interface to the intercom.  This one is a little frustrating.  I have a BT stereo module, and the interface between the headset microphones and the mic input works fine.  I can make a call with my cell, and I sound fine on the other end.  However, the intercom music input is designed for speaker level outputs.  The BT module has line level outputs.  I have another one that will, like many others I see, drive speakers — but it has no mic input and the speaker drive is not suited for common ground.  I don’t want to add a separate stereo amplifier, but I may have to.
  2. The second board will allow switching between the Garmin GPS and a BT serial connection, so I can drive the autopilot from my tablet running Avare or Naviator.  This one needs a little tweaking but will be OK.  I had assumed since the BT serial module has a 3.3V output, that it is non-inverted serial.  Nope.  It’s inverted.  Tomorrow I’ll do some mods to turn the inverting level shifter in a non-inverting level shifter (it’s just a 2N7000 and a couple of resistors).
  3. Have not even assembled the third one yet, it’s a lower priority.  This one will let me add a canopy latch alarm to the Dynon D180 equipped RV-12.  I’ve gotten good about latching the canopy before the run-up, but I’d still like to get this board working.  It piggybacks the canopy latch on the spar pin line, and alarms if the spar pins don’t show as latched (kind of important), OR if the canopy is not fully latched AND the engine is above 3900 RPM.  That way you can start up and taxi with the canopy propped open, but it will alarm during the runup if it’s not latched.  To do that we have to monitor the serial data stream from the D180 to grab the engine RPM.

 

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A new regulator for the Rotax 912

Depending on whom you listen to, the Ducati regulator supplied with the Rotax 912 ULS in the RV-12 is either a good, solid piece of equipment or a failure just waiting to happen.  I have not had mine fail, but I have noticed that the charging voltage is a little low.  I don’t think I have ever seen it above 13.7 V while in flight, and it’s lower on the ground.  Given that Odyssey recommends 14.2 to 14.7 V charge voltage, I’d like to see it a little higher to get as much life out of the battery as possible.

I’ve read quite a bit on VAF about replacing the original regulator with one designed for John Deere garden tractors.  The compatible John Deere part number is AM101406, and aftermarket replacements are readily available.  They’re everywhere, as a matter of fact.  As it turns out, it seems to be a pretty popular regulator for other applications as well.  At $30 a pop or so, delivered, they’re pretty inexpensive as well.  The only challenge is mounting it, since the hole spacing on the Ducati is wider than the JD item.  The Ducati regulator is about 3-5/8″ between the hole, while the JD replacement item is more like 2-3/8″.

There are several ways to skin this cat.  Some guys have installed an additional nut plate.  My plane is built and I really don’t want that hassle.  I wanted to use the hardware I had on hand, and be able to switch back to the original regulator if needed.  Since mine has not failed, it will be fine to use as a spare.

Below are pictures of a mounting plate that I fabricated from some .125″ stock I had on hand.  Actually it was part of a piece of AL angle stock, with one side cut off with a band saw.  I marked and drilled holes to match the Ducati regulator, then counterbored 1/2″ holes on the bottom to clear a pair of AN3 bolts I had on hand that just happened to be exactly the length I needed.  This mounting plate allows me to use the original pair of bolts to mount the assembly in the plane, and if it ever becomes necessary I can drop in the original regulator with the same bolts.

A brief ground run confirmed that the charge voltage holds steady at 14.2 V down to about 1700 RPM or so, where it drops off slightly.  I noticed none of the voltage fluctuation I have seen with the Ducati regulator.  I’ll throw the original in the plane for a while just in case, but so far it’s looking good.

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Various stuff…

First of all, sue me…  I’m loving the iPhone.  I never thought I would.  There are a few little annoyances, but overall it’s a great little widget.

Went to the Ak ARC flea market Saturday.  I had a table to sell kits, but I don’t know why I bothered.  I did (just barely, maybe) cover my breakfast, the table and my gas to drive there and back, so I guess it was OK.  Honestly, I think most of the stuff for sale was the same crap I’d seen last year.  There was, however, a table set up by the Omaha Maker group, and separately a ham had a 3D printer running printing out something or other, I never did figure out what.  So why did I go?  It was good to see and talk to some of the hams I only see once in a while.  Jack WA0SAQ was there, Dave WJ0Z and some others I seem to only see once every year or five.

I did some CNC engraving on the end panels for a new flavor of PicoKeyer.  I think it turned out pretty well.  It will be a little extra work — OK, a lot of extra work, but I think it will be worth it.  This will also probably be the motivation I need to finally break down and make a better fixture for the end panels I use for the boxes.  Maybe something I don’t have to stand there and hold each one in place.  It would be a worth a lot to me to be able to not stand there the whole time the mill is running, holding parts and trying to avoid getting an end mill through a thumbnail.  McMaster, here comes an order!

And…  some days I miss not having something that looks like airplane parts in the garage.  In a couple of weeks, though, I should have a “canoe” going and by Spring it should be looking airplane-y again.

That is all.

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On the home stretch!

After a week or so of work, we’re getting a lot closer to being finished with the big jobs in the garage.  The floor is looking pretty good; we still have the last section to do but that should only take a day.  Lisa will be the first to get to park on the new floor this afternoon when she gets home from work.

The epoxy paint seems pretty tough!  I slid the deep freeze across the floor to get it back where it belongs.  It’s usually a pretty big PITA to move around, because there are no slides or even feet on the bottom – just bumps in the sheet metal on the bottom.  It left a trail of light gray that just wiped -ff — I think it was just concrete dust from previous moves, maybe with a little appliance paint.  No damage to the floor, other than knocking off a few of the decorative flakes.  After a quick swipe with a damp rag, you can’t tell where the drag marks were.  I don’t know if I mentioned it in my previous posts, but after MUCH research I decided to just go with the Rust-Oleum epoxy garage floor paint.  It was readily available (Home Depot had it on the shelf) and not as expensive as the other options I was looking at — which means, if it starts coming up in a few years I haven’t spent $2500 on the floor like one of my neighbors.  Yes, his does look better and he had other people do the work…  but hey, I’ll spend some time and effort to move a decimal point!  I figure I have spent well under $400 on this, including the grinder rental and painting supplies.

I wanted to have a utility sink installed, but the quote from the plumber to do just the bare minimum work so I could do all of the actual installation and drywall work…  well, it was simply insane.  I guess we’ll run a hose from the laundry room when we need water out there.

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The garage madness continues

The past few days have been a lot of work.  Friday afternoon I rented a diamond grinder from Honeyman Rent-All and spent several hours grinding the floor.  I had to completely empty everything out of the garage into the driveway and yard.  Of course it all had to go back inside when I finished around 1 AM.

The diamond grinder was pretty easy to use.  It’s a little noisy, but not bad enough to get the neighbors complaining.  The hose connects directly to it to keep water flowing to keep the heat and dust down.  I was able to do all of the grinding, rinsing and squeegee-ing in about 4-5 hours.

Saturday I rinsed the floor and used the citric acid from the Rust-Oleum epoxy paint kit.  Probably unnecessary, but I had no other pressing need for two bags of citric acid.  It also cleaned up the inch or so that the grinder couldn’t get right up against the wall.  Then I spent another hour or two rinsing the floor, followed by the squeegee.  After the second round I used the shop vacuum to get it as dry as possible.  It’s looking pretty darned good right now, so Sunday will be painting day.  I have prepped both sides, but the third bay will have to wait.  I simply can’t empty everything out of the whole garage for a week.

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More CNC goodness

I’ve been using the M3 CNC machine quite effectively to produce machined cabinets for one of my ham radio kits.  In a couple of hours the other day I was able to greatly improve the machine control programs for producing three of the parts, making the machining process faster and less hassle.  I’ve even posted a couple of Youtube videos of the machine doing its thing.

I’ve got two new kits that will have optional, custom modified cabinets.  For these I am hoping to do a little more complicated work.  In addition to various round, square and/or rectangular holes in end panels, I’m going to try some engraving to label the connector locations and maybe put a logo on them.  That will take a little more development work, including making a jig to hold the parts in a rigid, repeatable location.

The machine has been a real life saver in modifying some existing cabinets.  The manual process using a file was very time consuming, very difficult, and produced imperfect results.  Using the CNC mill gives me perfect results in about half the time of doing it manually…  and I can be doing other things while the job runs, coming back only to swap out parts when the program is finished.  I may eventually be investing in a new Gecko G540 driver, which should make the machine smoother, quieter and much faster.  For now, though, the cheap ($65 or so, including shipping) Chinese driver board is doing the job.

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CNC to the rescue!

I’ve got a big box of very expensive parts that all need to be modified due to a screw-up in a circuit board I had made. Tossing either the boxes or the boards is out of the question. I can fix the cabinets with a file, but doing so takes a lot of time and does some nerve damage to my fingers.

Enter the CNC machine. I bought a 1/32″ end mill and wrote a short program to shave exactly the right amount of metal from each hole that needs fixing. Now I can do one cabinet every 4 minutes, every one of them is perfect, and it’s far less stressful on the operator (me). The only trade-off it that it’s pretty noisy, between the CMC machine and the shop vac to suck up all the metal shavings.

I love this machine… 🙂

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First parts coming off the CNC machine

Last night I successfully ran my first “real” jobs on the CNC.  One was a jig to hold a number of PIcoKeyer-Plus cabinet end panels, which came out perfectly.  Then I used that to actually mill an end panel, which also worked exactly as I had it set up to do.  Today I’ll run a batch of end panels, and set up a jig to drill tiny speaker grilles in the cabinet tops.

It’s almost scary how perfectly the stuff is coming out.  I’m still learning about tool selection.  For example, I assumed a 4-flute end mill would be best for doing the cabinet because it will produce a smooth finish.  However, I think a 2-flute would be better.  I’m also learning how much material can be removed, and how fast, to get the best results.  Speed control for the spindle would be good, but for now I’ll settle for just getting the stuff done!