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[4]

Building a Pulse EDM machine

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NEL957

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#31
Mark
It is wonderful to hear you so excited about the EDM. Looking forward to all the progress and how versatile it is to use. Keep the spirit and do not over do it, we want you around for many projects.
A Healthy Happy Project
Nelson
 
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#32
Mark I'm so happy for you and glad to see your jumping right into an awesome build.
Thank you GOD for answering our prayers for Mark AMEN. I'm looking forward to this they are Kool.
 

mark_f

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#33
Mark I'm so happy for you and glad to see your jumping right into an awesome build.
Thank you GOD for answering our prayers for Mark AMEN. I'm looking forward to this they are Kool.
Thank you. I'm doing well but still dealing with the mini strokes. I guess they are a crapshoot. It either happens or it doesn't. The docs are watching and doing everything they can think of to prevent a major problem.
 

mark_f

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#34
I am working on the ram while waiting for other parts.
IMG_0523.JPG IMG_0525.JPG
The slde and lead screw is assembled with the gear motor. I still have to install limit switches, a depth stop, and an electrode holder.
 

Billh50

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#35
Mark,
If you need any decals for your panel I have some vinyl decal paper and can print them up for you. Just need a drawing with sizes. These are water slide decals with a white background. Or I have regular clear water slide decal paper.I
 

mark_f

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#36
Mark,
If you need any decals for your panel I have some vinyl decal paper and can print them up for you. Just need a drawing with sizes. These are water slide decals with a white background. Or I have regular clear water slide decal paper.I
Thank you Bill. The control font panel is being engraved at a local engraving shop. But I will be looking for lettering for the head of the machine. I will let you know when I get that far.
Thanks.
 

Billh50

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#37
No problem....offer has no expiration date.
 

mark_f

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#38
I did some research with the manufacturer of the resistors and decided to change the setup to be more efficient. I made these heat sinks from some aluminum bar stock. They should work adequately with the fan blowing over them.

heat sink.JPG heat sink2.JPG
 
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#39
I did some research with the manufacturer of the resistors and decided to change the setup to be more efficient. I made these heat sinks from some aluminum bar stock. They should work adequately with the fan blowing over them.

View attachment 226731 View attachment 226732
Would some holes drilled thru the fin bottoms let more air circulation for cooling. Just wondering ?
 

NEL957

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#40
Love that heat sink what is the size of it?
Nelson
 

ch2co

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#41
Did you mill out or saw cut the fins? Cool little arrangement.
 

mark_f

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#42
Would some holes drilled thru the fin bottoms let more air circulation for cooling. Just wondering ?
Actually.... no. The surface area of the heat sink dissipates the heat ... thus the fins , to increase surface area. The air bowing through the heat sink will help carry the heat out. I use a high grade thermal compound between the resister and the heat sink to aid heat transfer.
 

mark_f

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#43

mark_f

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#44
Did you mill out or saw cut the fins? Cool little arrangement.
I used a .125" slitting saw to mill the grooves every .250". They were easy to make. About 3 hours to make the whole thing.
 

mark_f

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#45
This is the front panel I had engraved. next is to mount it on the cabinet front. I will spray 3M adhesive on the back to hold it in place.
etched front panel.jpg
 

mark_f

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#46
front panel and meters.jpg The panel is glued onto the front of the cabinet and the meters installed. Tomorrow I will begin installing the switches.
 

rwm

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#47
Wait...those meters are analog...I forget how to read them.
R
 

mark_f

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#48
Wait...those meters are analog...I forget how to read them.
R
LMAO ......... I like analog meters , but after I ordered them I saw digital meters for the same price.
 

savarin

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#49
a beautiful job progressing with awesome speed.
I cant wait for the end result.
Congratulations Mark.
 

brino

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#50
For this application I bet analog meters are better. If the pulse supply works anything like my simple R-C EDM supply, the voltage will jump around a bunch due to the discharges. The analog meter will tend to average that out, a digital display might be too jumpy to read easily.
-brino
 

tweinke

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#51
Mark awesome project! I am positive this will be an inspiration to others here.
 

mark_f

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#52
For this application I bet analog meters are better. If the pulse supply works anything like my simple R-C EDM supply, the voltage will jump around a bunch due to the discharges. The analog meter will tend to average that out, a digital display might be too jumpy to read easily.
-brino
I think you are correct about that.
 

ch2co

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#53
Brino has it right. Digital meters are NOT the thing to watch varying signals with. The meter movement follows the source with a needle that you an actually see
moving (smoothly) back and forth while a bunch of numbers flashing on a DMM will impossible to follow unless the change in signal is slow enough to be able to watch.
(I thin that makes sense) An oscilloscope can follow the changes quite well too, even a digital one:distracted:
 

ch2co

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#54
Dang it Mark I was still punching buttons on my keyboard when you clicked Post Reply. You should be more courteous to our elders.;)
 

mark_f

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#55
a beautiful job progressing with awesome speed.
I cant wait for the end result.
Congratulations Mark.
Charles,
I have to thank you because you inspired me to do this build by seeing your simple spark eroder. I originally set out to build a tap burner, similar to yours, but many moons ago I ran a large EDM machine in a machine shop, and decided it would be better to build a full blown machine as there is so much that can be done with it.

I am making a PDF file of the complete build as I go (with pictures) And will post the file here at the end of the build.
 

mark_f

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#56
Dang it Mark I was still punching buttons on my keyboard when you clicked Post Reply. You should be more courteous to our elders.;)
LMAO ........:laughing:
 

rwm

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#57
I'm sure you are right about the meters. That cabinet is looking fantastic.
R
 

petertha

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#58
Hi Mark. Coincidentally I was just reading about that design. I'll be very interested to see your machine in action.

I'm not really up to speed on how they work in the case of broken taps, maybe you can explain the fundamentals? Do you size the plunger (wire or electrode thingy?) to be a certain % of the embedded tap body? For example, let say I broke a 3mm tap [0.118"]. Would you make the wire, say 0.0.090" diameter so it burns the center core of the tap body but doesn't affect the threaded portion to preserve the tapped hole condition? And then what, the outer thread remnants still clinging are weak so you can pick them out? Does the EDM know any difference between a dissimilar parent material? For example HSS tap stuck in aluminum part, could you burn a larger hole through both steel tap & aluminum part simultaneously like 4mm [0.157"] like to prepare it for a tapped permanent plug?

For a case in point example of attempted broken tap removal in aluminum using often recommended alum solution, my example here.
http://www.homemodelenginemachinist.com/showthread.php?t=26470
It didn't end well for whatever collection of reasons as mentioned in the post, despite cases where alum appeared to work for others. It's behind me now. I concluded it was entirely due to incorrect tapping head depth setup. But I think it would be wishful thinking that I'll never see another broken tap one day. For kicks I tried drilling out the tap with a carbide ball end mill. It sure didn't like gnawing on the top of it. I didn't want to ruin an expensive EM on a remedial experiment & thought a carbide drill would have to be precisely centered without wandering, so called it quits. I was coming to the conclusion maybe a high speed grinding spindle with abrasive bit pecking mode could take it down a million shavings later.
 

savarin

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#59
Being somewhat clumsy I have have had a large number of broken taps, mainly 4 and 5mm but only in steel.
My simple machine burnt them out without damaging the thread so I could pick out the flutes from the hole.
I used a 3mm copper bit for the 4mm taps and a 4mm brass bit for the 5mm and my (simple) machine is not a precision piece of equipment so probably didnt exactly follow the centre.
I havnt tried in aluminium (yet) but I cant see why you couldnt burn out a larger hole to plug.
Mine is a slow process so a 5mm tap took approx 3 hours total to clean.
 

mark_f

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#60
Hi Mark. Coincidentally I was just reading about that design. I'll be very interested to see your machine in action.

I'm not really up to speed on how they work in the case of broken taps, maybe you can explain the fundamentals? Do you size the plunger (wire or electrode thingy?) to be a certain % of the embedded tap body? For example, let say I broke a 3mm tap [0.118"]. Would you make the wire, say 0.0.090" diameter so it burns the center core of the tap body but doesn't affect the threaded portion to preserve the tapped hole condition? And then what, the outer thread remnants still clinging are weak so you can pick them out? Does the EDM know any difference between a dissimilar parent material? For example HSS tap stuck in aluminum part, could you burn a larger hole through both steel tap & aluminum part simultaneously like 4mm [0.157"] like to prepare it for a tapped permanent plug?

For a case in point example of attempted broken tap removal in aluminum using often recommended alum solution, my example here.
http://www.homemodelenginemachinist.com/showthread.php?t=26470
It didn't end well for whatever collection of reasons as mentioned in the post, despite cases where alum appeared to work for others. It's behind me now. I concluded it was entirely due to incorrect tapping head depth setup. But I think it would be wishful thinking that I'll never see another broken tap one day. For kicks I tried drilling out the tap with a carbide ball end mill. It sure didn't like gnawing on the top of it. I didn't want to ruin an expensive EM on a remedial experiment & thought a carbide drill would have to be precisely centered without wandering, so called it quits. I was coming to the conclusion maybe a high speed grinding spindle with abrasive bit pecking mode could take it down a million shavings later.
You pretty much answered your own question. You can burn the center of a tap out and pick the pieces out. On a larger tap, you can make the electrode from brass tubing and burn down the flutes leaving a center core. This will make it go faster.
As Charles said , it takes some time depending on the current used , but I would rather spend three hours removing a tap and saving the part than as I have had to do in the past. Spend 6 or 8 hours beating and picking broken pieces and still doing minor damage to the part.

You can burn a hole as small as .040" with an EDM.
 
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