1994 US Electricar Repair Blog by Mike

I just got the huge 4 farad cap in the mail. Yesterday I found a nice Tektronics chassis at Halted that use to be some old test instrument. If it will hold all of the larger spot welder assemblies, then it will fit on my bench very nicely as it’s narrow. The chassis was designed to sit on either of two sides. I just need to start the assembly process.

If you have not noticed or heard, I’ve opened the US Electricar.net store for USE owners so they can get repairs and parts to keep their vehicles running. There are links on this blog to take you there. Enjoy!

The 10 tooth L series pulley and belt arrived from McMaster today. The pulley had to be bored out from 3/8″ ID to 5/8″ ID to fit the Z axis motor. Now the motor has much more torque against the quill. I turned up the speed a bit and it still moves very quickly even though the ratio is much steeper. It also helps the Z axis gain some more accuracy.

Today I finally got a fixture together to wind the T1 transformers that fail on the Dolphin chargers. I used an IR led pair tied to a counter to tell me how many windings were made. I wrote several types of G-code to have the cnc mill help in the winding of these parts. It worked out well in the end after several iterations. I settled in the 532-540 ohm range after they were wound. This was a few turns under 3k. I have one more transformer to wind. I’ll take some better video with a better source. It took days to figure all of this out and get it built and tested. The original estimate for rewinding was 15 hours. By working on the G-code and the cnc hardware I knocked is down to just over 2 hours. But last night I had a better idea. Now the full rewind takes 5 minutes while the hardware counts every turn. Sweet!

The brightness of this IR led was too high. The Rx led did not like so much light. These pics were taken with my G1 cell phone since the human eye cannot see Infra-red light. Thanks to Bob at Halted for that great tip! Video camera with night shooting have the same capability of seeing IR.

This brightness worked well. I might even be able to drop it a bit more, but for now it worked fine.

Here is a winding video from my G1 cell phone. You need Quicktime to play it. I didn’t sit still long enough to show that the transformer is moving up and down via the cnc. It spaces the windings out very nicely. I borrowed the counter from my automated battery load tester.

The new quill cover for the Bridgeport that I got from Don is now installed. I oiled it up nicely and the quill moves well up and down it’s full range of motion now.

It occurred to me today that I could design a dropin replacement for the Dolphin’s filter caps, HV buss, and IGBT hardware under the main board. It would be put together a lot like the ACP cars. Separate igbt’s in parallel for each phase. Several filter caps too. This would make getting parts far easier. There is a a lot of volume to work with under the main board. I’ll have to draw it up in cad sometime to see how it will physically fit. I should dig up the ACP pics I have as well of their hardware.

Not only did I FINALLY get the cnc system debugged after blowing it all to hell last weekend (along with my truck), it looked like the main filter caps and the fets could simply just be upgraded in voltage. This would prevent that last disaster that blew everything up and the system would get a nice increase in feed speed. The parts upgrade works great!! Wow, it went from 75ipm to 125ipm. It’s been up to 160ipm. But it was a little too unstable. At that speed there was a little oscillation at high rpm. Can’t tell if it’s the hardware or the pc that is the limiting factor. Makes it tempting to upgrade this old 800mhz pc to an old 3ghz Pentium. The faster the pc the faster the parallel port speed.

While debugging the cnc system, the quill suddenly stopped going fully upwards. It was hitting something hard. I called Don and he said the sheetmetal quill cover had broken tabs and was floating around. So tonight I called him and he walked me through how to take the top of the Bridgeport head apart to get the quill cover out. It was just a little work. Don nailed the diagnosis. I’ll get over to his house in the next day or 2 and pick up a new one from him.

Later this year, I will have had the mill for 10 years. Don has a guy that might sell him a real Bridgeport CNC machine. He won’t jump on it unless I give him the ok. It’s not a bad price. I could sell my Bridgeport to get some of the expense back. Those original cnc’s have power oilers, chrome ways and very wide ways at that, along with ball screws on all 3 axis. The tables are not long and skinny. They are a lot deeper. They were made for flowing lots of coolant on them. Don says the drawbar is some kind of quick change set up not the standard BP stuff. I told him we’d have to make it a step pulley setup. But maybe not. As long as it fits in my garage it won’t matter. Besides if I have to sell it, having it original would be more appealing to a potential buyer.

After delivering several more Dolphin boards it was time to assemble my system. I turned the key and as soon as the ready light comes on there was a gun like pop! I had forgotten to connect the igbt driver cables. At least the main board was not affected. All 3 igbt’s are shorted. I am lucky that my last customer was willing to give me his 3 spare igbt’s.

The #2 and #3 main boards that have received the Classic Dropout mod shipped today. They work very well compared to when I first got them running. What a thrill to finally see such great success with a problem that plagued these vehicles for years.

Fritz put up his fet board for sale today. It’s a beauty! It’s made from 3 oz copper. It should handle the current spikes nicely. I have to decide to either have Shawn make me one of his chassis for the welder or just use a short PC tower that are super cheap but probably require some labor. Maybe a cool transparent case would look sweet. I am only waiting on the fets to arrive from Hong Kong and the board to arrive from Fritz. I still need to order the 4 farad capacitor too.