Painting

Actual Painting Starts

This weekend real primer and paint were applied.  After months of body work including fiberglass filler, body filler and endless scrapping of 5 layers of old paint, I was able to start to paint.  As with most, the prep is never done, so there comes a time when perfect enough is good enough.

Plastic drop cloths hung from ceiling, the garage spray booth was ready.

Sprayer of choice - Earlex 5500 HVLP Spray Station

Paint System

Martin Senour Cross/Fire family

1. CE430 LCF Etch Primer on the bare metal and fiberglass bonnet (2 coats)
2. CP440 Gray 2K Urethane Primer (2 coats)
3. 56 Basecoat - Marshall Red 
4. CC5020 Clearcoat
5. Used the CR733 reducer for 55-70 degrees. The garage was between 60-65 during the paint sessions.

All of these were mixed as instructed on the datasheets.
The 1.5mm tip/needle for all of the coats.
16 oz of each primer for these 4 parts.
24 oz of paint and clear to for 2 coats on the 4 parts.  Heavier coats were used to achieve good wetting.

One note, the 3M VOC respirator breathing mask is amazing - I never once smelled a fume.

Here is the progression of the fiberglass hood/bonnet

Raw, unpainted

After the etching and 2K Primer

With 2 coats of base color and 2 coats of clear coat\

Results: There is mild orange peel visible so I expect once the rest of the car is painted, there will be a wet-sanding day along with polishing to achieve the best possible finish.  It will be easier once these parts are back on the car.

The doors and boot cover (trunk) also came out well:

A significant improvement over the stripped versions:

3D Printing a Steering Wheel Hub

3D Printing

Jane has never had the center hub of the steering wheel.  This left the bolt exposed and looking very unfinished.  Having looked on-line and not knowing exactly what steering wheel is installed, I figured this would be a good project to learn about 3D Printing.

I took some rough measurements of the hole size to attempt to get a good press-fit for the hub.

Using TinkerCad to draw the hub and a MakerBot 3D Printer to print it,
after some fine tuning to get the dimensions just right, the resulting part looks good and is fairly solid.

You can see the 3D Model here.

Here is what it looked like as a drawing



After some sanding, priming and painting the final hub is shown on the right.  The left is an unfinished version and the middle was a failed attempted at painting.

This is what the bottom looked like to cover the small bolts and press fit into the wheel

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Here is the hub installed.

Wireless Comms in a '73 Mini

Wireless Fuel Gauge

Up to now, Jane's fuel gauge was driven by an Arduino Uno that is monitoring current via a Shunt in and out of the battery pack.  This has worked well but it require a comms wire be run from the boot to the dashboard to power the fuel gauge.  Since the fuel gauge had to be isolated from the 12V system to maintain complete isolation of the traction pack from the rest of the car.

This week's project involved replacing the wire with a wireless system.  Using two nrf24L01+ 2.4GHz radio boards that cost about $2.00 each, the system now communicates wirelessly from the current monitoring Arduino Uno to the dashboard Arduino Mega.

 nrf24L01+ board

These boards communicate over the SPI port on the Arduinos and only need 2 additional digital lines for chip select.  Using the RF24 library, it took about 15 minutes to connect these and have a two exchange between the Arduinos.  To assure reliable comms, the radios were set to 250 Kbps and maximum output power and retries.  The system has no problem communicating from the boot to the dash and these radios have a acknowledgement system, so comms are quite reliable.   The dash radio sends a request for data and the battery system send back charge level, current current and time that the system has been charging.  Since this is less than 10 bytes, it goes quite fast.

For the dashboard Mega that is also driving a Sainsmart 3.2" color LCD, an SD card, a Touchscreen and the CanBus interface for the Kelly Controller, I ended up adding a softSPI interface since connecting to the standard hardware SPI interface introduced some issues.  After a couple of hours of unsuccessful debug, it was easier just to grab 5 unused pins on the Mega and setup the greiman Soft SPI bus.   This worked great and did not interfere with the SDCard which is the only other SPI device in the system.  Also, Megas are known for noisy 3.3V supplies, so I added a simple LM317 regulator with the appropriate resistors to get a 3.3V supply from the 5V line.  The radios run between 1.9V and 3.6V so a precise supply was not critical, just a clean one which was done with a few large caps.

With the battery monitor now is communication with the dashboard computer, a new feature was added to the dashboard computer.  By touching the screen, the system will switch to a battery view which shows charge level and current battery current.  This will allow for an easy comparison between battery current and motor current.  The real test will be comparing the reported power of each which should provide some additional efficiency data.   Also, the dashboard computer will now drive both the original fuel gauge and temperature gauge, simplifying the overall system and isolating the battery system from the dashboard.

New Primary Gearing

The second time is the charm

Recently the primary gear (22A1493) started to make some noise and it has always been slightly non-centric.  Well this was motivation enough to make a second attempt at attaching the gear to the ME0913 motor.

In the original Mini engine, the primary gear spins on the crankshaft and couples the clutch plate to the transfer gears which go to the transmission.  Normally, the gear spins with press-fit bronze bushings which is oil fed through feeder holes in the gear.

With Jane, the primary gear is firmly attached to the electric motors shaft and transfer power to the transfer gears.  The challenge is the Primary gear has an ID of about 1.75" and the ME0913 motor's shaft is 7/8".

A shaft coupler can be used to adapt these two, however, the inside of the Primary Gear is not a consistent diameter but actually 3 different diameters.  These vary by about 0.1" by design (1.5" - 1.62").  The center section has a smaller ID (~1.504") than the outer sections.  Therefore, additional adapters (bushings) must be made to permit a press-fit between the coupler and the gear.  The two new bushings were designed to match the diameter of the inner section (shoulder) so that the coupler will have consistent contact through the length of the gear.  The gear is hardened steel and could not be easily machined.

Here the keyed shaft coupler is shown press fit in bronze-aluminum bushing pressed into the primary gear.

This is the other end of the assembly showing all three elements (Gear, bushing (bronze),  coupler (inner black)).  Note the thickness difference in the bronze bushings (Front vs. rear)

Additionally, a grade-8 bolt was installed through the gear-bushing-coupler to transfer power and hold the assembly together.  With only 40 HP, the Grade-8 bolt should provide sufficient shear strength.  The coupler was cut flush with the front of the primary gear.  The other end of the adapter fits flush with a feature on the motor and is held in place with a bolt through the shaft.

You can also see a new seal (black rubber LUF10005) installed that will keep oil from leaking along the gear.

The first time this assembly was made, the original bushings were turned to accept the coupler but since the gear is difficult to chuck-up in a lathe, it was impossible to machine the inside of the bronze bushings concentric with the outside of the gear.  This resulted in a slight acentricity and it was visible as the gear was turned by the motor.  I suspect this added to the noise coming from the primary gear.  The new custom bushings should be perfectly concentric resulting in a better fit and hopefully reduced noise.

Success

The new gear assembly is in and here is a video of it in motion.  No visible non-concentricity and it is much quieter. Also visible is the good oil circulation for the primary gear train.  

Some photos for higher details.

Stripping Paint

Time to focus on the paint

Now that the mechanics seem to be in reasonable shape and the rains have started, it is a great time to get the body in order.  First step, strip off the paint.  Now there are many opinions on the best way to do this from chemical to sanding to wire brushes.  Not having a lot of space for chemical strip, I tried both the 3M paint strippers in an angle-grinder and 60-Grit sand painter on a orbital sander.  Both work well but progress is slow.

Best I can tell, there are at least 4-6 different paint jobs of paint the car.  Yellow, Green, Red, Green, Grey, Blue, White.  Here is a geological photo of an sanded area.  The bare steel looks great but it takes a lot of work to get down through 40 years of paint.

Then I read about using a razor blade to strip paint.  It works.   here is a video showing the stripping a a couple of layers.  The razor avoids lots of dust and chemical mess.  It  takes a lot of razors as each one lasts for about a square foot of scraping, but at $7.00/100, it is still quite economical.

At this point, about 70% of the metal is scraped but the detail work is still pending.  Several more weekends to go....

Great Service from Kelly Controller

Bricked Controller

Well after attempting a firmware upgrade on my Kelly KHB 72701 controller, the master FW failed to program and the controller was frozen.  The team at Kelly offered to reflash my controller if I sent it to them.  I used USPS Global Express service, I was able to send the dead controller to Kelly and it arrived in about 4 business days.  Global Express is a partnership with FedEx so the box moved by USPS across the ocean but was then handed off to FedEx for the local delivery in China.  Full tracking information from both USPS and FedEx was available online.  The team at Kelly, reflashed the unit and shipped it back (2 day service from China) to me for no charge, which is quite generous since the unit is over 2 years old and a year out of warranty.  The controller arrived in great shape and came right up.  I wish all companies had this level of customer service.

Noise on the Ground

Well the new controller highlighted a problem I had with my timing advance circuit.    I'm not sure if some wiring clean-up exposed this or the new firmware has slightly different timing for the phase signals from the motor.  Either way, my timing advance system stopped working and started causing the controller to report either a non-spinning motor or a hall-phase error.  Bypassing the timing advance board cleared the problem, so it was obvious where the problem was centered.

After some sniffing around with a scope, I found there was a lot of noise on the phase sensor signals from the motor.  I could see the phase signal but a high-frequency 2V noise was riding on top of the low-frequency motor phase signals when the motor was spinning.  Looked a lot like the high-voltage PWM from the controller, though I never measured the frequency to confirm.

Two realizations:

• The case of the controller is tied to the high-voltage motor signals through large resistors to drain residual charge once the controller is turned off.  The team at Kelly suggested that if the case was tied to chassis ground, it could be introducing some noise on the 12V ground.  Isolating the controllers case from chassis ground (with a rubber mat) improved the noise quite a bit, but there was still an issue with phase signals.
• More digging revealed a wiring issue.  Originally, I had used the ground signals (RTN) from controller as the ground for the hall sensor in the motor.  I suspect the controller was passing some noise through the ground lines to the hall sensor.  Switching the hall sensor ground to be the sourced from the timing advance system (a good chassis ground) provided a significant reduction in the noise on the hall sensor signals.  I suspect the Kelly Controller is more tolerant of noise or has some high frequency input filters which my timing advance circuit does not.

After these two changes, the timing circuit is operational again and the controller is reporting All-Good.  Now to re-optimize the timing settings based on the new firmware.  After driving the car without the timing advance active, it will be much more fun to have it operational again given the noticeable performance boost.  More testing this weekend....

Kelly KHB 72701 Controller Settings

Kelly Controller Settings - Screen shots

The following are screen shots of the current settings in the controller.  These are delivering optimal performance with the Motenergy ME0913 motor and timing advance system.