Perfect Compact Circular Saw From a Dinosaur
Intro: Perfect Compact Circular Saw From a Dinosaur
I've never had a dedicated shop space.
Also, my projects are rarely on a very large scale.
That's why I love small and compact things: they don't take much space and can be stowed away when not in use. The same goes for my tools.
I've wanted a circular saw for a while. But all the standard offerings are large and frankly they are overkill for my purposes.
Small (cordless) saws are perfect for hobby grade use and occasional projects, and they are really cute.
They were popular like 10-20 years ago, but today not as much (certainly not on a budget).
The latter gives us an opportunity to make a modern version with a tiny investment.
Making it Lithium powered and charged via USB makes it the perfect choice for a small scale DIYer like myself.
Do you want one? Follow along!
And if you liked this instructable, consider voting for it in the Build a Tool Contest. Thank you!
STEP 1: Getting Your Saw
This particular tool comes in two flavors:
1. Craftsman model 900.112650
2. Black&Decker VP600
It's the same saw just different colors, you can get either.
It uses a 3 3/8" blade and supposed to be powered with 7.2V (2x3.6V VersaPaks) - an ancient NiCd batteries.
You can find tons of listings on ebay, here are several examples:
Mine was 6$ w/o shipping, so it's very cost effective.
Mine came in descent shape, but there may be variations.
Also, you might have one laying around and collecting dust, in this case it's free.
**Note: There are other tools which use 2 VersaPak sticks, this instructable will also apply there.
STEP 2: What You'll Need
1. The saw :)
2. Two 18650 Lithium Ion cells. Something like this, or this.
3. 2s USB charger, like this one. I used it in this build, and it works surprisingly well.
4. 2s bms (optional). I used this one, but it's not recommended (more on this later)
5. Female charging jack, here or here.
Some loose wiring.
Access to 3d printer.
T10 screwdriver (for disassembly)
Hot glue gun.
Soldering iron.
Hand tools.
STEP 3: Open It
First thing first: Take the blade off! (seriously do it) it will be much safer this way.
Keep the two washers and the blade retainer bolt somewhere safe. The bolt is left threaded and can't be replaced easily once lost.
1. Push out the two c-pins that hold the base plate to the body (one is longer). Wide enough screwdriver and light hammer taps will do the trick.
2. Unscrew 8 T10 bolts that hold two case pieces together.
There isn't much to do inside, just clean the dust/dirt from years of storage.
Make sure the on/off unit is functional.
STEP 4: Print the Cap(s)
You can find the .stl files here - Thing: 3512505
cap1.stl is required
cap2.stl gives it a little more bling :) and it's optional.
The lithium batteries will be placed in the same compartment as the old ones.
But they are smaller in diameter, so an adapter is needed.
The locations for lithium cells are not centered, this is done on purpose.
STEP 5: Make the Power Unit
It's time to make the juice unit that will drive the saw into the future.
- Take your female charging port, solder wires and secure it in place, see pic. Route the wires out.The nut is a bit challenging to operate, but it's manageable and you can add hot glue for final fix.
- Solder pieces of wire to the batteries. One cell to the positive side, one cell to the negative side.
- Push these in the 3d printed adapter with the wired ends in. There is a channel to route the wires in between the cells.Secure with hot glue.
- These two leads come together to the BM pad on the BMS unit.
- Secure the BMS unit to one of the cells with hot glue.
- Run the other ends of the batteries to the B+/- pads.
**Side note about this BMS unit: Ideally charging leads and those that go to the motor should be connected to +/-P pads on the unit. However, this one is probably faulty (for me or the basic model). So I ended up connecting everything to +/-B pads. Effectively this cancels the functionality of the BMS - so it's entirely optional.
***Please let me know if there is a 2s BMS unit that worked for you. Thanks!
STEP 6: Make the Charger
Take the charger unit and snip off the black connectors.
I've found a piece of power cord with correct plug, you'll probably have something like this laying around.
If not, get something like this.
Solder the leads to appropriate pads.
Then put some hot glue on the interface between the cord and the charger.
Heat shrink it all, you're done.
For heat shrinks, various sizes, just get this. You'll thank me later.
It's a good idea to charge your newly assembled unit and check that everything works.
STEP 7: Grease It (if You Are Already Here)
As long as the unit is open, we might just go ahead and give the gears a treat.
There are two stages to the gearbox. Each one is enclosed in separate compartment and held by it's own bolts.
Open them up and grease the gears with generous amount.
STEP 8: Wire It Up
Take your power assembly and put it in the case where it should be.
Then take the output wires and solder them to the contact leafs inside the saw
Positive goes to white and negative to the black.
Put several blubs of hot glue to secure it in place
Close it and you are done with the hard stuff.
Now, you can add the "vanity plate" to the end. Just for fun.
After all, it's not an ordinary saw now.
STEP 9: Put the Plate Back & Optional New Blade
Depending on the condition of your plate, you might want to get it clean.
I cleaned the rust with dremel tool and these wire heads.
Then cleaned it with alcohol and sprayed with black paint.
To place it back, push it in and re-insert the c-pins
You are done.
Now you can use your saw with the original blade.
However, to get better results and cleaner cuts you can get much better one.
I've got this one, and it's definitely worth the 6$.
Enjoy,
Dani
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8 Comments
christopherjhansen 7 months ago
I've been watching videos on how to super charge the batteries with LiON or
NiMH but given how old my saw is (circa 20+ years) I'm no longer interested in
monkeying around with batteries that don't stay or keep charges. I have 8
NiCD batteries for this saw and its sister tools like a drill and rotary
(Dremel). I had the idea after watching how to "hack"
batteries, to instead just wire a 7volt adapter to the leads and just use it as
a plug-in/corded saw. I think I've tried to use this saw perhaps 5 times
in 20+ years. As you would guess, all 8 batteries are garbage in
2023.
It occurred to me I might be able to hack a battery, to have
live wires connected to the positive (male) terminal and live wire attached to
the negative terminal. Then just slap the battery into the port, plug the
7volt adapter into the wall, and off you go. I don't have a 3D printer or
any way to create a new battery case, so I'm thinking just solder a wire to the
positive and one to the negative terminals inside the saw and then wire up the
adapter from there.
The Question: You mention in step 8 to solder up white to positive and
black to negative. I wanted to double check this. I’m attaching two
pictures for you to look at. I know on a
standard battery (like a AA) the knob end of the battery is the positive
terminal and the bottom is the negative. Take a look at image 1 and 2 and let me know if you concur with
this. It seems reversed to me by nature
of AA batteries and I wanted to double check.
This instructable was super helpful.Getting the “C” bars out was not intuitive to
me, so your directions helped a ton with that. I was able to open my saw up just like your pictures.
Thanks for the great instructions
Chris
medanilevin 7 months ago
In AA batteries and also in loose LiOn cells the knob is the positive, and the casing is negative.
However the batteries we use in power tools are an assembly of several cells and every manufacturer does it differently on the outputs.
My suggestion to you is to start with a battery, open it up and trace the positive and negative leads/tabs. A simple DVM can help here. Then in your saw the leads should be a mirror image.
Dani
christopherjhansen 7 months ago
Thanks for the quick reply. I know the post is older and you've moved on to newer and greater things I'm sure. So again, thanks. :-)
As I mentioned, my NiCDs are all dead. They don't hold a charge, so I'm not sure how I'd use a DMM/DVM to check polarity? When I look at the batteries, I believe my pictures with polarity notes are "wrong" and in fact quite the opposite. The positive connector should be where the female (middle) portion of the battery engages with the saw. The negative connector is the larger metal contact leafs that touch the outside of the battery. This mirrors the AA design as well. The only difference, is the positive is male on a AA vs female.
I mention this, because I think you might have it mislabeled in the Instructable, and I'm not an electronics guy, so I thought I'd ask. If the black wire is the negative and it connects to the outside of the battery, then it should be the white bottom wire on Image 2 that is soldered to the contact leaf that engages the outside of the battery. Right?!??
Thanks again for taking time to engage on the questions here. I love what you did here for your saw, its just not a real option for me without a 3D printer and how often I use the dumb thing, hard wiring it makes sense to me given I wont waste anymore money on batteries for this saw. LOL :-)
medanilevin 7 months ago
Sorry, too much time passed, this is out of context for me. However in your picture, the red labels are reversed, you can see it on the lithium cell.
One more idea for you, if the saw is that old, no harm will be done if you reverse the polarity for a test. Note the direction in which the saw must rotate and connect it to the power supply. The worst case you'll have to reverse it afterwards.
Do me a favor and do this WITHOUT a blade attached.
Dani
JoanSaga 4 years ago
medanilevin 4 years ago
Do you have the original battery?
If so, you'll have to replace the internal cells from NiCd to Lithium.
We might take it to private.
Dani
JoanSaga 4 years ago
medanilevin 4 years ago
Thank you for the comment.
For 18v I don't know of any suitable USB chargers, as these deliver around 5v, but there are ways you can do it.
Show me some pictures of the saw and your intentions, I can walk you through it.
Dani