Introduction: Milwaukee Battery Adapter for Harbor Freight Bauer V20

About: Born in Alabama - Over educated - Arizona transplant - Inventor - Product Developer - Small Business Owner - Educator

Ok, Folks.

Sorry for the lack of documentation. I was playing the development fast and loose (we printed up six of these to get to the current version, making tweaks each time.) a smidge ago I found a bauer V20 drill in the middle of the road, so I will go back and take the missing photos while converting it to take our batteries.

You'll need (to already own) a Milwakee M18 charger and battery. With the weed wacker it is really worth having 3AH or more because these things EAT batteries... anyway.

You'll need some EPOXY glue so that your stuff stays put.

You'll need a 3D PRINTER (because I'm not printing and mailing these things... but you can, just give me attribution and link to our site (telling people they can download and print the file for free if they have their own printer.. don't be a dook) The file is downloadable here:


Philips Head Screwdriver

Box Cutter, Snips, or something for carving plastic.

Epoxy Glue

Your favorite plastic carving device (I used an ancient pair of wire snippers and a dull box knife. Ideally you'd be using a sharp blade. Dull blades claim fingers.)

A Harbor Freight Tools Bauer V20 battery powered tool (tool only)

3D printer or 3D printed adapter.

Step 1: Get to Printing That Dingy Dang Old Adaptor!

This is the fun part! (it isn't - which is why we get our robot slave to do it for us. No one wants to hold a hot glue gun full of stinky plastic for 7 hours, so THANK YOU Zoe (the name of our delightful little Zortrax M200plus.) If you were a human we'd have torched all of your brain cells by now.

So the file can be downloaded here from my Fusion360 account.

I printed 2 layers with 20% infill. This isn't a high stress part, so thing should go well with minimal infil. You do you. You know your machine better than I do. If you don't have one, check out your local libraries or your kids schools (or your parents schools) whatever gets you to a printer. IF they are working, folks will usually let you play with them.

Step 2: Remove the Screws Holding Your Battery Slider Together.

Next you'll need to open up the BAUER V20 tool you are converting. This is relatively safe because there is no powersupply (it's unplugged so to speak)

You're looking for small Philips head screws . The weed wacker has 6. Don't loose them. Put them somewhere safe. I think 5 of them were the same and 1 was a bolt with a nut (DON't LOOSE THAT NUT)

There might also be a screw under the black trim piece near the front of the handle. Look closely. Should pull apart easily when you have all the screws.

Step 3: Pull Out the Switches

So, when the pieces come apart there will be some wiring and a trigger switch and a spring and an electronic switch (looks like a limit switch to me. The world is all made up of exchangeable parts. That's why all my ex-girlfriends left me for better (wo)men.

Take a photo! (I didn't) so you know where everything goes back together.

You want to pull out the black pieces with 3x metal blades coming out of it. This piece needs to be shaved down to fit through the hole in your 3D printed part (you can see it in the photo after I've glued everything together and screwed over the first attempt at a set screw terminal)


I started by snipping off everything that stuck out past the blades on the side and the clips that register the part and secure it into the handle.

When I got close I'd try threading it through the hole in the 3D printed adapter and shave off plastic where it was still to big. Be patient. Don't force anything. just keep shaving brah.

Step 4: Reassemble the Handle*

So you want to put that bad handle back together WITHOUT the black part with blades. You'll want to tug the black part out so it's hanging out it's original hole in the handle. Again, a photo is worth a thousand words and I failed you.

you could also consider that I did all this work and shared it with you so you didn't have to print 6 adaptors to get one that worked. Jeez. be more thankful why dont you? (If we get that chainsaw you'll see so many photo updates)

Don't forget to put the spring in the trigger. Use your photo to see where everything goes.

If you don't have a photo think of it as a puzzle. You'll get it. Don't give up

Step 5: Slide on the Adaptor

Slide on the adapter into the original battery slot while pulling the black bladed thing you shaved down through the square hole in the adapter


the wiring on the black bit is real snug and it's hard to navigate, but possible.

I have some XXXL hands and I had to use a set of needlenose pliers, but you may be able to get it with your fingeys.

Step 6: Glue It All in Place!

You'll want to epoxy this in place so that it doesn't move. The most stress will end up being on the black piece with the blades as its pulled by the Milwaukee battery when you pull it out to charge.

Maybe the set screw will work for you! I tried to fix it, but ...

You may need to bend the metal blades slightly for your Milwaukee M18 battery to slide into the adapter easily.

Let it dry!

Step 7: Wack Them Weeds!

or whatever.

Use your new toy. Pretend its a Milwaukee if you want. its the right color kinda =)