Tom Log

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Tom Griffing's Log

Tom photo.png

November 18, 2019

I have reviewed some welder circuits and watched some videos about welders and the designs use high voltage / low amps for the switching & control, then use a transformer to convert it into low voltage / high current for the output for the welding arc. They also include a power supply for the control electronics and multiple circuits for feedback control of the switching.

They also include filters to suppress the high frequencies to reduce the resulting EMI emissions.

Per discussion with Marcin, here is a link to a video we discussed about an evaluation of a 200A IGBT inverter welder:

200A IGBT Inverter Welder

Another video discussing welding transformers:

Welding Transformers

November 12, 2019

OK: Time to get started again. This time, analyzing requirements for the Universal Power Supply.

Stated requirements:

  1. Light Dimmer
  2. Welder
  3. Cordless Welder
  4. 18650 Battery Charger
  5. Motor Power Supply

These are all related to power delivery, but the applications vary widely and the requirements list design specifics that might best be updated.

Since some of the stated requirements are so simple, yet different from others, I will consider them separately.

1. Light Dimmer: The requirement call for a rectifier and a PWM circuit to deliver pulsed DC to an incandescent bulb, whereas typical light dimmers use the combination of a diac and a triac. The triac design is far simpler. I found a very simple circuit that would be easy to replicate:

Screen Shot 2019-11-12 at 6.15.04 AM.png


It appears that the goal is not to dim lights, but rather to make a PWM power supply for further use. With that in mind, I'll start searching for welder designs.

2. Welder: While the spec calls for input of 120VAC @ 20A, this would require a special receptacle and plug, as well as a 20A circuit breaker. Most household receptacles for 120VAC are only capable of 15A max. Here is an image of a 20A receptacle:

White-leviton-electrical-outlets-receptacles-m02-cbr20-wmp-64 400 compressed.jpg


The intent is most probably for generic household electricity, so we should scale back the power to 120V x 15A = 1800 Watts (or: 1.8 kw)

I found a design for a welder using IGBTs, however it is for 230VAC supply, with text in czeck - but it is a good place to start: [1]

Welder-igbt-schematic.png Welder-igbt-schematic-voltage-feedback.png

Another good source for circuit designs is from the manufacturers, as they try to make it easy for their products to be used.

This is a page from Fuji Electric, with designs for welders using their IGBT modules:

Fuji IGBT Modules for Welding machine

I have a HUGE preference for using IGBT modules over discrete parts, as connections are more robust, larger heat sync mounts and simpler assembly. Also: multiple components are in packaged in one housing and they are optimized for one function, like choppers and H-bridges.

3. Cordless Welder

4. 18650 Battery Charger

5. Motor Power Supply

October 9, 2017


I've been thinking about how to mount the motor to the hydraulic power unit:

 Solar Power Cube Front.png Solar Power Cube - Front View

As shown, the offset motor / gear assembly is awkward to mount and will extend beyond the Power Cube frame (one frame member removed for clarity).

I designed a bracket assembly, but have resigned to re-using the bolt holes in the motor's gear assembly for mounting to the plate on top of the power unit:

 36V Motor Front.png 36V Motor - Front View

The bolts must:

* Provide motor support
* Prevent the motor from tilting with increased belt tension / torque
* Allow the motor to slide from side to side to adjust belt tension

October 8, 2017

Preparing for the Solar Power Cube ... Solar Power Cube Working Document

I have to get everything designed in time to order parts for the workshop. The question has now come up for the pulleys and timing belt and how to attach them to the shafts of the motor and pump. The pump side is easy - 1/2" and positioned higher than the motor. Attaching the pulley for the motor is another question, though the motor is somewhat lower than the pump shaft and the motor shaft is threaded on the end.

The initial question is: Do we make the pulley to screw onto the threaded shaft or slide over the lower part of the 20mm shaft (or both)?

The followup question is: Is a lathe (and someone to run it) available in the OSE workshop in good working order for machining and/or threading the pulley to match the shaft?

Also: How do we purchase the pulley material - in discrete pulleys or in "bar" material?

 5mm pulleys.png 5mm Pitch Pulleys
 Polytech 5mm Pulleys
 5mm bar material.png Pulley Bar Material
 Polytech 5mm pitch bar

Note that the motor pulley will have to be longer than the pump pulley for the belt:

 Belt Pulley Orientation.png Belt and pulley orientation

The length of the shaft shown is short and won't extend through the length of the pulley, so we will have to improvise a solution.

The main "gotcha" is that the full specs of the shaft aren't given - like the shaft length and the threads on the end of the shaft.

OK ... I finally found a closeup of the shaft:

 Motor gearbox.png Motor Gearbox and shaft

April 22, 2017

Checking out the OSE Wiki pages to see if they are read-write . . .

March 20, 2016

Packing the 3D printer for the return trip. Visit with Alec to see the updates on the Micro House 3 and discuss possibilities for utilizing its solar panels.

March 19, 2016

Workshop began - lots of unloading and preparing supplies for the workshop. Built a printer along with the other participants, but had to leave before testing. One local participant offered the use of a facility nearby, so we packed up and drove there. Successfully tested all printers with only one "smoker", which was repaired for total success. Ended at 12:30 AM and drove back to Factor e Farm.

March 18, 2016

Arrived at OSE, checked out the amazing bok choy growth in the greenhouse and the two new puppies. Helped prepare for the 3D printer workshop. Testing the Porteus software distribution with the 3D printer. Cut aluminum plates for the printers. Packed workshop supplies for the morning trip to the workshop location in Kansas City.

March 14, 2016

OK ... there's been a gap in my log. Concerning the upcoming lab for the 3D printer, the original ISO file for the Linux distro wasn't bootable from a memory stick. The site shows how to convert an ISO file into a "hybrid" file, bootable from optical or memory stick:

Here is the original ISO image that didn't work well for booting from USB sticks:

D3D Live ISO

Here is the image for the 3D printer workshop that has already been converted:

D3D Hybrid Live ISO

All that needs to be done is do a raw copy of this file to the USB stick using "dd" (Linux), "Disk Utility" (Mac) or some similar disk utility.

Update: The "ddrescue" program is for data recovery and it addresses a different function.

The "dd" command (ie: "Data Dumper") that I mentioned writes data from an input (ie: ISO file) to an output (ie: the USB stick).

First: Identify the device for the USB stick. You can use commands like "lsblk", the "fdisk -l" or the Ubuntu "disks" GUI to find the device. In a single disk system, the "/dev/hda" device is your main hard drive and "/dev/hdb" is often the USB stick. The following writes the ISO to the "sdxx" device:

dd if=Porteus-D3D-Workshop-x86_64-v2.iso of=/dev/sdxx bs=1024b

Please note that the "dd" command performs a raw write and will overwrite the destination device (ie: "of=..."), including all partitioning, formatting, data, etc.

Marcin Notes

sudo apt-get install gddrescue - installs ISO creation program ddrescue

July 26, 2015

Worked on OSE wiki, fixed an issue with the user account approval.

July 25, 2015

I've been working on multiple fixes and updates for the Power Cube design and recently changed it to version 15.7 in the 3D Warehouse. The changes were adjustments from the results of the July Power Cube workshop.

July 15, 2015

Gasifier Workshiop, Day 2 Torched some steel for the gasifier folk. Didn't get much done as there was a personnel issue. Spent time resolving it and documenting jigs. Marcin bought 5 T Shirts and we discussed further sales - I told him that I could ship them individually.

July 15, 2015

MicroTrac Workshiop, Day 1 Focused mostly on finishing the Power Cubes and with the updates to one engine to enable operation with the gasifier.

July 15, 2015

MicroTrac 2.0 Workshiop, Day 3 Worked on Power Cubes and assisted from time to time with the MicroTrac. Welded the plates in the hole punch to prevent drift. The MicroTrac T Shirts arrived - Sold several.

July 14, 2015

MicroTrac 2.0 Workshiop, Day 2 24 links completed! Discussed the idea of a fab shop in a shipping container.

July 13, 2015

MicroTrac 2.0 Workshiop, Day 1: Late start, as Marcin had an eye issue. Worked with Will Turner to make a jig for cutting and punching chain links. Problem with hole punch - dies getting out of alignment. Made first batch of tracks and tested.

July 12, 2015

PC 15.6 Workshop, Day 3: Met with Marcin and Jonathan for planning, then went to the workshop where everyone was gathered and working. Integration day - we found some design issues along the way:

  • The 4 x 4 tube at the rear of the engine had to be removed before the engine / muffler could be seated.
  • The geometry of the return plumbing could not be used intact and the oil filter had to be unscrewed from the bracket.
  • The keyswitch on the old control bracket conflicted with the 4 x 4 tube and had to be rotated 90 degrees.
  • The 1 1/2" coupling was made of cast iron and posed a problem for welding the Hydraulic Reservoirs.
  • The wiring harness diagram had two wires crossed, which burned out the diodes before the magnetos.
  • The bolts securing the bottom of the oil cooler expanded steel to the lower tube could not fit through to the back side of the tube, as the Hydraulic Reservoir was there - so it would have to be secured with short bolts from within the tube (difficult).

These issues were overcome and four of us (Jonathan, Natalia, Will and I) worked on one Power Cube and finally got it going.

July 11, 2015

PC 15.6 Workshop, Day 2: Met with Marcin and Jonathan for planning, then went to the HabLab for discussion before continuing. Continued welding tanks and started on assembling the modules - oil cooler, return plumbing, pressure plumbing, After burning out the diodes, found some replacements in the HabLab, replaced them and got the Power Cube working around midnight.

July 10, 2013

PC 15.6 Workshop, Day 1: Met with Marcin and Jonathan for planning, then went to the HabLab for introductions and lecture. Spent the time cleaning up the shop in preparation for the workshop. Proceeded afterward to the workshop, held the safety briefing and started the build. We planned to do the "dirty stuff" today, cutting steel & welding. The tanks took the full 3 days to complete. Moved the LifeTrac near the door, ran the hoses between it and the iron worker and cut steel for the tank end plates. Only one MIG welder worked initially. Marcin told me what had to be done and I disassembled, replaced liner and wire on two other welders to get them working.

July 9, 2013

Continued cleaning the shop and organizing for the workshop.

July 8, 2013

Arrived at KCI. Marcin arrived in the truck and we drove to MoKan Fasterners for bolts, Harbor Freight for tools and then for Factor E Farm. Spent several hours resolving automotive issues. Spent time organizing the shop and layout out supplies.

June 19, 2015

Updated MediaWiki with extension to require admin approval for new accounts. The other means of blocking spambots just wasn't working. Uploaded newest Power Cube 15.6 BOM.

June 1, 2015

Updated MediaWiki to enable ReCaptcha. Still having some issues with bogus user registration.

January 17, 2015

Power cube arrived this week (Yahoo!). After the shipment, the shipping company charged me an additional $84.60 for a "limited access fee". They claimed the fee is standard across the shipping industry when delivering to schools/universities.

January 13, 2015

Power cube shipment delayed to avoid holiday shipping maddness. Shipped Power Cube kit (ie: Power Cube, less engine & battery).

October 26, 2014

Received an order for a Power Cube, Version 7, less the engine. I've been updating the Sketchup model to include the pressure relief valve and the updated BOM for current pricing. Now to complete the model & BOM and start ordering parts tomorrow. I've also begun inquiries about information about sensors for the hydraulic flow, pressure and temperature - to accommodate new power cube certification requirements.

MicroHouse 4 Workshop

Attended this workshop to get better acquainted with MicroHouse design and CEB construction techniques.

Tue Sep 30, 2014

Back to Dallas.

Mon Sep 29, 2014

Met the electrician from the power company with connectors and tools. Replaced connectors and added MicroHouse wiring. Installed electrical conduit, elbows and ran wiring from the electric panel to the MicroHouse for all lights, sockets, stove and dryer. Other crews completed the roof and began installing windows.

Sun Sep 28, 2014

Painted initial coat on the plywood side of lower roof modules to save time later. Upper roof module construction using screws, 2" x 6" x 16' boards and struts. Other crews installed the roof modules. Dug trench and set conduit into ground for incoming and outgoing cables. Connected the incoming cables to the box main power and prepared connections for the cables to the MicroHouse 3. Secured the electrical connections on the MicroHouse, as it is to "go live" in the morning.

Sat Sep 27, 2014

Lower roof module construction using screws, 3/8" plywood, 2" x 6" x 16' boards and struts.

Fri Sep 26, 2014

Completed digging the trench for the electric cable. Met the electrician from the power company, who opened up the panel only to find that we would need replacement connectors to continue. Closed the panel and informed Marcin of the situation. Worked with several teams to set the CEB blocks for the walls and to make additional blocks from soil and lime. Walls mostly completed today.

Thu Sep 25, 2014

Worked on Micro House misc tasks - including preparing landings and placing the hydronic stove. Checked out the electric panel at the MicroHouse and prepared it to "go live". Drove to Menard's to get supplies for wiring the electric cables from the Micro House to the panel on the workshop.

Wed Sep 24, 2014

Caught a ride to OSE, Missouri with Marshall (from Austin). Checked out the progress made on the Structural Frame Power Cubes and gave a few suggestions for completing one kit.

Sat Sep 14, 2013: 50 HP Power Cube Design

We've had a lot of discussion about the new PowerCube and the new LifeTrac designs and I think I have wrapped my mind around the new frame design. Here is a screenshot:

LifeTrac 35.png

Latest 50 hp Power Cube Suggestion: File:PowerCube 35

Thursday, July 8, 2013

Drove up to Missouri and to Factor E Farm for the Power Cube / LifeTrac build for Blair Grocery in New Orleans. Spent time designing the new Power Cube with the Kubota diesel engine. Drove to secure the engine, radiator and other parts necessary for the build. Used Sketchup to update the design according to the newly secured Kubota engine. Cut steel for the new 36" frame and began gathering other necessary parts - such as the fan and oil cooler.

James Slade arrived and received instructions to assist with Power Cube development. The crew from Blair Grocery arrived and were oriented for assisting in the build of the LifeTrac. The LifeTrac and Power Cube development proceeded at the same time.

I headed back to Dallas and a few days later, the LifeTrac was functioning and was loaded onto the trailer for transport to New Orleans with the 27 hp Power Cube and the unfinished Kubota Power Cube. The transport stopped at my farm in East Texas, where the Kubota Power Cube was completed, loaded in the LifeTrac, tested and then loaded for shipping to New Orleans - where it was tested successfully.

PowerCube Kubota.png

Latest Kubota Power Cube Design: File:PowerCube

Thursday, May 25 2013 (Date needs verification)

It's been some time since my last update. The latest activity concerns the new Power Cube design - using a Volkswagen engine. I expect to meet with Jay early this next week to complete the rebuild of the engine and secure the engine. I still have a few more parts to get - especially for mounting the shaft coupling and engine mounts. I have been working on the component layout for the new Power Cube - it will be quite different from before, as the engine/pump mounting is horizontal rather than vertical. Also, the plumbing and engine are larger and heavier and I will be adding a pressure relief valve. The sizing of the hydraulic pump has been a big issue and is documented here:

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