January 2011

All 3 of the knobs are machined. They just need the set screw hole drilled and taped.

Here are the scope pics from my spotwelder and from Fritz. Mine is on top.


Only the knobs need to be machined and installed. One prototype knob is installed on the 3rd pot for reference. Foot switch jack is the rear of the chassis.

Today I finished up the copper interconnects on the spot welder. It came out great. Such a tight fit. Mechanically very stout and it looks great. I fired it up and attached my scope to it. The cap and fet output pulses were cleaner than the ones on Fritz’s site. But his is a year old.

I finally figured out a way to mount the lcd. It will hang from the upper front frame with these delrin blocks. It will look great not having a cutout and screw heads sticking out the front of the bezel. I wish I could get a darker bezel to better hide the interior. I’ll have to hunt online for some. Tap plastics only that #54. It was the darkest they had. So tomorrow I will mount the lcd and cnc the bezel. The probe materials need machining to turn them into probes too.

Today was about getting all of the high current hardware machined, taped, bent, and installed. Had to make a couple of delrin spacers to help anchor the bus bars to the chassis. The cap negative cable needs to be large gauge. So I have to find out which has the higher cross sectional area. One #2ga or a pair of #6 or #8ga cables. My 6, 8ga cables are very flexible and will be easier to mount. Turns out it will take 3 6ga cables to best one 2ga cable.

The first bezel was cut so oversize and it turns out that it was difficult to modify on the mill. So I bought 2 more bezels rough cut far closer to the correct dimensions. I’ll machine them tomorrow and test fit them.

Here is the spot welder hardware mounted inside the chassis. A couple more pairs of wires need installation. Both copper bars for the electrodes still need to be bent and machined. The front bezel needs to be machined and mounted.

I was told this morning that I’m now banned from Fritz’s dual pulse 600Ws blog. I’ve been on the project for 2 years. I’ve even been to his house where he showed me his entire setup. I just now had the time to build the spot welder. Since Fritz does not have his documentation online, I had to email him with questions. One question about R27 being installed or not was already answered on his support tab in the blog. I missed that. But when I asked about some instability in the cap voltage regulation that I had experienced when I reduced the resistance of the discharge resistor bank, he spoke to me in a very condescending manner in his blog. So I wrote him about that. I told him never to speak to me that way. So he banned me from the blog and threatened to never answer me back on email.

He has told me over email that he is sick of the welder project. Here is a quote from an email to me. “I know I started this thing but I want to throw up when I hear the word “welder” “. He is also working hard on the plasma cutter adaptation of this spot welder. Having met Fritz, he is not the most patient man in the world. He didn’t know what having an internet project like this would bring him. He complains of having to go 200 emails with someone to find the problems with their welder. He complains in email to me about how he has actually had to have folks send in their board for him to fix. I have not done any of this. Not by a damn mile!! I bet in 2 years I only exchanged 20 emails total. Most were this past week. This project is simple for my skill set. It worked the very first time I powered the welder up. He is just seriously burned out and pissed off at the world. I’m just a convenient scape goat for his misplaced anger. I bet he has done this to other members as well. But since he controls the posts to his blog, we never find out. Another good reason to start our own 600Ws Dual Pulse Spot Welder support group.

I built both boards without the manual. I only had 3 questions. One about R27. One about about the jumpers for D9 that I saw pictures of in other builder’s welders but did not find anywere else. The 3rd was from instructions in the manual that clearly said to reduce the resistance of the discharge resistor bank. I did just that. It worked great. When I had gotten the discharge time down to where I liked it, the voltage on the cap was not stable. The fet was working too hard. This is when Fritz saw fit to come down on me with condescending statements in his blog. I sent him an email telling him to never talk to me that way. I also told him that I totally understood his position, as I have been there in a few of my own internet based projects and the tons of questions that come with it. So he banned me then and there.

I’m really hoping that other members would be willing to get together to talk about their welders. I’m curious what probes they are using as well as what settings fit the materials they are using. So I will be starting a group just for that exchange of ideas if any of the members contact me. I’m at mikep_95133 at yahoo.com.

Fritz says the twitching on the cap voltage is due to the very low resistance I now have on the discharge load. Even though his manual says to lower it for faster discharge, he made it sound like I screwed up by trying it. Here is the url for Fritz’s homemade Dual Pulse 600Ws spot welder blog. http://frikkieg.blogspot.com/ He’s been a bit impatient, rude, and over worked lately. I think it’s time to start a forum so owners and builders can chat and exchange ideas without Fritz over reacting.

The huge 4 farad cap now has it’s delrin mounts machined and installed on the base plate. It will be held in place with tie wraps that pass through the delrin mounts. Next it will be time to cut and bend copper bar to attach the welding probes to the system. Also I have to turn the probes on the lathe. Everything is a tight fit but it’s going to work. I wanted a chassis that could fit on on of my benches. I have some great ideas how to clean up the appearance of the front panel.

You might be able to see the extra heatsinks I added to the components on each side of the cap centered in this pic. This is for days when the spot welder is being used in warm environments. I’m using fans that draw 350ma so the 24v reg will get warmer. I may connect the fans to the 36v supply using a dropping resistor so the 24v supply won’t have any extra load.

Fritz had me remove the 22v zener in the over voltage protection circuit. The cap was then able to charge to 20 volts. It did work very hard from 18 to 20v however. Q4 that drives the charging, was working far harder than usual. So I put the 22v zener back on the board. It seems that the zener limited the cap’s voltage to a perfect level. The zener has a suffix on the part number that shows it’s actually a 20.5v zener. Each voltage has 4 different levels. Mine was the lowest end of the 22v range. Fritz said I needed a full 3 farad cap in order to get to 20v. Mine only tested to 1.6 farad. It’s an audio cap rated at 4.0 farad. Why is it that audio stuff is always playing a numbers game with their ratings?

So now I have some new lower value resistors that I’ve tested on the discharge side of the spot welder. I really like the responsiveness of these resistors. But the voltage regulation has become twitchy. A bunch of mounting and fabrication of parts is all that hold back getting this spot welder finished.

Also ordered a foot switch recommended by Fritz.

Just did a light test on the fet board. First I powered it up. Then attached an ohm meter across the fets. When activated, the meter read close to zero. Good sign. Next I went and added a power supply at 12 volts, but current limited to 3 amps. Went fine. With light duty testing it seems to work. Looks like the next step is to connect it to the output of the control board and somehow simulate the load of a weld being made. The large 4 farad cap is just connected with jumpers. Nothing that can move much current. So we’ll see how that works for testing.

Still lots of machining to do. Still need to get the front panel layout designed and then machined. I still don’t have a clue how to mount it yet. The bar and round stock of copper arrived. So the welding probes need to be machined as well.

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