Custom DeWalt machining project ...

wquiles

wquiles

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After making this project, a forum member asked me to make him one to use at work. His main requirement was to make it brighter. So I looked back at the compromises I made with mine, and decided to see what can I do better in this one.

So I started by buying a new host for this project at the local Lowe's:
20140707_080516.jpg




To keep costs lower, I always try to reuse left-over stock, and I happen to have a rod of aluminum of about the right diameter:
20140719_162201.jpg




First face off and prep for knurling:
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This is the side that will hold the electronics:
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Then thread the ID to match the OD on the plastic host. It was not quite 16 nor 18TPI, but I picked 18TPI, and checked often after each pass:
20140720_123531.jpg




Not too bad:
20140720_125357.jpg


20140720_125415.jpg





This internal cut will be for the electrical post (details later):
20140720_131230.jpg




HUGE chunk of Aluminum, but we are not done yet:
20140730_082033.jpg




My customer wanted his light to be brighter than mine, so I went to XP-G's, specifically the second generation, (XP-G2), and I opted for a mix of the cool white and warm LED's, to give more output than on mine, while still preserving color rendition:
20140801_135654.jpg




So I started work on the LED side, of course making sure the OEM plastic lens would be completely enclosed:
20140802_113701.jpg


20140802_115046.jpg


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To hold the electrical post, I am drilling a hole in this side for a retainer screw:
20140802_120255.jpg




Since these 18Volt packs come out at 20Volts fully charged, and since this is a PWM-dimmed, direct-drive configuration, I decided to go with 6x LED's in series:
20140802_121007.jpg




Using my laser for positioning on the indexer:
20140802_122800.jpg




Lots of machining:
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Picking the right end-mill for the next machining operation - this will give me a little bit more throw:
20140802_125647.jpg


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Getting LED's ready for reflow soldering:
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Time for the thermal epoxy:
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Wire then up and test them:
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You see here both the flood, and a little throw as well - this worked better than I expected:
20140802_191047.jpg




Work on the electrical post took a long time. The idea is to "replace" the bulb, so that both the positive and negative contacts run through this post, so that the head can be interchanged without any wires/connections. This will allow this head to be used with other similarly threaded DeWalt hosts, as long as they are running from an 18Volt pack:
20140803_114845.jpg


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Drill and tap the base:
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Then work on the battery side:
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Then work on the Delrin piece which will hold the positive contact:
20140803_123855.jpg


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Press fit:
20140803_125037.jpg




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As designed on paper, nearly identical to the bulb it will be replacing:
20140803_130513.jpg




Hole for the electrical positive wire:
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Positive contact:
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This is how it looks when inserted into the plastic host:
20140803_132410.jpg





Then started work on the electronics. I needed a few extra boards, a few extra LED's, so I do them all at the same time since it is all surface mount components:
20140809_093307.jpg


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My Tiny85 controller boards and FET switches (for the PWM dimming) ready to go:
20140809_120831.jpg




For the negative side of the battery, I drilled and tap a hole in the side:
20140809_125234.jpg




Test fit of the boards. The micro controller board monitors both the battery voltage AND the temperature of the heatsink, to adjust the output automatically, and to prevent over-discharge of the pack (although one should not leave it turned on, as the pack will still have parasitic drain):
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Testing phase (looks like a miniature operating room, right?):
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Epoxy boards and wires in place. I am using thermal pads in each board to provide thermal path and to isolate the boards electrically (heatsink is at ground/negative potential):
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More testing:
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Completed module (without lens), compared to my first (prototype?) conversion:
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Note the back of the controller board (white board) has all of those small holes - those are the programming pins for the Tiny85. I am in dialog with my customer via email to define his default preferences/values, as this software I wrote has 3x output levels (cycle ON-OFF-ON to cycle the levels), and also has optional memory for last level used. This makes the head re-programmable by me during this final phase of testing:
20140809_172520.jpg




Mine/original on the left, my customer's on the right:
DSCF1945.JPG




After all of this mambo-jumbo machining/electronics - how does it work?

(camera on manual exposure)

Old on high, then new on high:
Old_high_33.JPG


New_high_34.JPG





Another set. Still a flood light, but the new one also has some throw:
Old_high_36.JPG


New_high_35.JPG





From the side (note silver heatsink on right-most side of the picture):
Old_high_42.JPG


New_high_43.JPG




I hope the new owner likes his new work light :)
 
DrafterDan

DrafterDan

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That's some nice clean work there. Thank you for sharing!
 
Norm

Norm

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Well put together mod and thread, great reading :goodjob::kewlpics::wow:

I think I'd blur your signature in your first picture.

Norm
 
Str8stroke

Str8stroke

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I wish I was your friend! lol Awesome project & documentation. Thanks for the post.
 
precisionworks

precisionworks

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Great job Will!

Any thoughts about a variable dimming option (Surefire U2, SWM V10R, etc.)?
 
B

blah9

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Great job! Thank you for sharing this. :)
 
wquiles

wquiles

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Thank you guys :eek:


I think I'd blur your signature in your first picture.
Done - thanks :)


Great job Will!

Any thoughts about a variable dimming option (Surefire U2, SWM V10R, etc.)?
It already has 3x output levels (low, med, high) selected like most clicky lights: by turning the light ON-OFF-ON quickly, it cycles through the 3x output modes. I also have optional memory (turn ON at the last level used). Doing it this way means there is nothing in the host/battery side that needs to change - I was just trying to keep things simple: just unscrew the original reflector assembly, and use this one instead.
 
T

TexasLumens

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Super nice work, great images, great light!!! Thanks for sharing Will!!! :twothumbs

Dan.
 
wquiles

wquiles

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OK, an update, now that I am doing the final, final testing. Yes, I know, I was doing final testing two weeks ago ...

But in talking to the owner of this work light, he mentioned he had access to a special setup that allows extended run-times by having 3x cells in parallel. Since 3x packs would hold high voltage levels longer, he and I talked about what could be done to make this light work on that setup.

As I mentioned earlier in this thread, this work light runs in direct drive mode, but with PWM adjustments/dimming, temperature monitoring, and of course battery voltage monitoring. But with the 3x packs in parallel, I suggest the owner to try software-controlled PWM levels proportional with the battery voltage - basically a crude "regulation" software control system.

I had the first version working 1-2 weeks ago, with voltage monitoring and PWM adjustments every 0.5 volts, and it worked great. BUT, the transition from one level to the next was a little noticeable. Not a night and day, but it was not "good enough" for me. So I asked the owner a little more time to try a different approach, and he agreed.

I approached my electronics mentor (who makes the great TaskLED LED drivers), and he suggested using a table, since the Tiny85 I am using doesn't do floating point directly. I consulted a couple of web sites, and found a way to simulate the voltage vs current equation for LED's [ current = a * e^(b*voltage) ], and then I empirically found and adjusted the constants to work with the voltage range of this pack. So I wrote new software for this method of operation over the last 1-2 weeks, and finally got it running well. For those interested, here is the link to the Excel template I used as a basis:
http://newtonexcelbach.wordpress.com/2011/01/19/using-linest-for-non-linear-curve-fitting/

The new monitoring system has 10x more discrete PWM values, adjusted every 0.1 volts, plus I also incorporated a new state in the control/monitoring loop to transition from one PMW value to the new one, so make it a little bit smoother. This new software of course can't match true regulation like that achieve with an LED current regulated driver, but it is nearly 100% efficient since the MOSFET switching element is always either ON or OFF, so efficiency is about maximum throughout the whole battery range.

The only transition that is quite visible is when the temperature monitoring finally quicks in, and switches the output from HIGH (default level, per the customer request), to MED. This helps prevent the head/heatsink from getting hot enough to burn the skin and of course helps protect and prolong the life of the LED and electronics. Once the temperature drops, the output resumes at the HIGH level (built-in hysteresis).

This was my programming setup during the testing/debugging of the software:
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Atmel AVR development platform:
20140816_204836.jpg




Example of the PWM waveform (about 1Khs frequency, so it is not easy for the eyes to tell the flicker - some folks are sensitive at the lower/common 256Hz). Here the duty cycle is at about 73%:
20140816_205129.jpg



I tested as high as 22.5 volts, which should be well above these rechargeable packs. I will admit that I don't have one of the newer LiIon packs, so I have no idea what would happen with those packs. Here I am testing the temperature hysteresis, by cooling the heatsink, and watching the output go back up to HIGH level:
20140830_135834.jpg



I sealed the OEM plastic lens with a thin coat of clear silicone:
20140830_143310.jpg



I am targeting shipping to my customer on Tuesday, so that he can "play" with it. If he needs minor adjustments/changes, I can quickly re-program it for him on my development/programming setup.
 
B

borrower

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Mar 10, 2011
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189
Wow! Great work. I shudder to think about the organs/limbs I'd have to sell to be able to afford your work.

Side note for anyone following in your footsteps -- remember to use neutral cure silicone (not the stuff that smells like acetic acid/vinegar) around electronics.
 
R

rioimmagina

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Aug 6, 2010
Messages
198
Outstanding work Sir!
And very catchy presentation!
 

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