Building a Pulse EDM machine

The recommended gear motor For the servo is made by Pittman. It is a 19.1 volt DC gearmotor with a 96:1 ratio. I will be running it on 12V DC. This motor runs between $100 and $200, depending on the supplier. I found one on eBay fr $22.
FullSizeRender.jpg This gearmotor assembly is about 1 1/2" diameter and about 3" long.
 
I went to the local surplus supplier today and got some aluminum sheet and they cut it to size for me. $20 worth of aluminum made my control cabinet. I used the pan brake I built last year to do the bending. This job almost paid the cost of building the brake. This control cabinet to buy already made costs wel over $250.
The cabinet is 17 5/8" wide, 13" deep, and 7" high.
IMG_0481.JPG IMG_0482.JPG IMG_0483.JPG
The little right angle bent piece will hold the Bank of power resistors.
 
Today I got most of the cabinet work done. It is amazing how much work is involved in making a nice cabinet.

These photos show the progress so far. Now it is time to start building.

The first photo shows the major component layout.
component layout.jpg
You may notice the cooling fan is going to mount inside the cabinet at the end of the "tunnel" that will house the power resistors.This fan will essentially be blowing air through the enclosed "tunnel" and directly out the back. This will most likely give the best cooling. It is more efficient than drawing the air through.
the vent hole in the back.


fan and vent holes.jpg
The same size vent "in" is needed to support the air flow out. There will be a filter with low air flow resistance to keep dust out of the cabinet and a wire guard on the outlet hole.


meter holes in cabinet.jpg
The meter holes are cut in the center of the cabinet front.


meters.jpg
I purchased a matching set of meters for the front.


power plugs.jpg
The AC inlet Plug and the Gap Power outlet plug are mounted in the rear of the cabinet.
I will now get to mounting the parts and begin wiring. I will also begin stuffing the PC board.

Mark Frazier
 
Looks like your doing it right, as usual. good to have you back Mark. Cheers, Mike
 
I could use a cold beer along with the peanuts and popcorn.
But I too am watching this impressive forum with anticipation.

CHuck the grumpy old guy
 
I got the fan structure finished and the fan mounted.
fan mounted 2.jpg

The fan essentially will blow through a box to cool the resisters. The fan is 100 CFM. I think it should do the trick. I have designed a bracket to hold the resistors in front of the fan. It will be next on my list.
fan mounted.jpg The "box" is completed when the cover is on.


A friend spent a lot of time making me an aluminum work tank from .085" thick aluminum. It is 18" X 12" X 8"
work tank.jpg
He cut it, bent it and then tried to weld it on the corners. No matter what we did we could not weld this aluminum. We called the supplier and found it it is not weldable. This aluminum is a cheap grade from china and it will not weld. They said it has to be epoxied, but the epoxy is horrendously expensive. So ...... I am going to pop rivet angles on the corners and seal the inside of the corners wit fiberglass if it will stand up to the dielectric or kerosene.... I think it will, but if anyone knows different, let me know. I hate to waste a nice tank.
work tank 2.jpg

Time to start wiring the control.
 
I was going to say 100% Silicone Sealant. But then I just looked up its properties and found out it does not like prolong periods of exposure to solvents? Maybe try a test piece first, if you go that route. Or get a plastic tub. You can repurpose a HF coolant tank from one of their saws in the parts list.
 
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