Introduction: 1940's Bandsaw - Make It Move ... One More Time
I wanted a good bandsaw to cut metal, plastic, re-saw smaller hardwood, and have variable speed.
Unfortunately, the cost for a variable speed bandsaw to run off of 120V is above $1000. Even at that price point, most of the motors are single speed motors with a capacitor start. I dislike capacitor start motors for many reasons and I'm confused at why it's so popular since we now have brushless DC motors to run battery powered table saws on jobsites now that can include variable speed control. Buying used or new brushless DC motors is not that easy yet, but I worked a little bit in the HVAC industry and learned that people often throw away 3 phase induction motors so you can buy or sometimes adopt these often incredible motors for under $100 or for free if you know an HVAC tech. The problem with 3 phase motors is that it's often running off of 220V 3 phase power supply and I don't have that readily available in my residential garage. Luckily, KB electronics (not a sponsor) has released a product that takes 120V input and outputs something that resembles a 3 phase 220V current that also allows you to control the speed of the motor. I'm currently taking a break from working, so I have time to look through OfferUp and Craigslist to find some old tools, motors, and experiment with taking a really old bandsaw that doesn't start and adding a 3 phase induction motor with variable speed control so I can cut whatever I want with it.
In this Instructable:
I hope to share what I learned and hopefully make it easy enough for others to upgrade old machines (lathes, drill press, bandsaws, disc sanders, etc.) with variable speed motors as well. As a disclaimer, I'm not a professional anything (currently funemployed) so please know that I'm not an expert in motors, electronics, or power tools but just a tinkerer that would like to have access to nicer tools at a lower cost point. I'm probably taking a risk that other experts would advise against, but I wear safety equipment and if I do anything that feels risky, I google search accidents with that particular task and actively search for ways to mitigate any risk that I can find.
- Some type of Bandsaw. I would suggest a pre 1970s Delta Bandsaw because the parts are still made an readily available. If you live near a bigger city, I think they can be found for under $200. The bandsaw I bought was from the 1940's based on the badge and lack of serial number.
- 3 phase Induction Motor. I would suggest between 1/2 Horsepower (~373 watts) and 1 Horsepower (~746 watts) to work with the drive below.
- KB Electronnics AC drive. Here's the link to the drive I purchased: https://www.kb-controls.com/product.sc?productId=...
- Small Cost Items:
- 4 x 16 ga conductor appliance chord
- I needed a new drive sheaves for my bandsaw
- I also needed a new drive belt but these are affordable
- New bandsaw tires were needed for my bandsaw as well
- Wire nuts
- Electrical tape
- Scrap lumber for motor mount
Step 1: Get Your Supplies
- Find your bandsaw. I would suggest getting your bandsaw first. Once you get an old bandsaw, you usually need to do a couple of upgrades like changing the tires on the wheels, oiling up all the moveable parts, and seeing how you want to mount your new motor to it's new location
- Find a 3 phase motor to work with a VFD. I used a 3/4 horsepower (~559 watts) motor which worked with the KB electronics AC drive that I purchased. 3 phase motors can be found on craigslist or offerup and they're affordable because not a lot of people play with VFDs or three have 3 phase power readily available.
- Get a VFD. I chose the KB Electronic AC drive because it can take either 120v or 220v power at 50 or 60 Hz. The best feature is that this drive works with a range of horsepower:
- 1/3 HP
- 1/4 HP
- 1/2 HP
- 3/4 HP
- 1 HP
- Hex heads for the bandsaw adjustments.
- Wire strippers for electrical work.
- Mallets and Hammers to persuade parts of your bandsaw.
- Adjustable wrenches was the main wrench I used on this project the most.
Step 2: Learn How to Wire a 3-phase Motors
- Label you wires with tape so it's easy to see
- Follow the diagram on your motor. I included a picture of how I wired my motor with notes on the picture
- For the most part, this Youtube video on how to wire a 3 phase motor helped me a lot to be more confident:
Step 3: Set Up the VFD and Connect Wires
- Follow the instructions from the VFD manufacturer (the attached picture is from my specific drive from KB Electronics)
- I had to add a jumper wire to run the VFD on 120v power
- Adjust the horsepower to run with your motors (I had to set my VFD to 3/4 HP for my Baldor Motor)
- There are a bunch of other options that the drive I have from KB electronics can do that I'm still exploring. It's very fun and a bit addicting
Step 4: Bench Test the Motor to Make Sure Your Electronics Are Right
- I clamped my motor to my
- Plugging in the VFD to the 120v circuit, I was nervous. I had a fire extinguisher ready but that was unnecessary.
- When I turned the VFD on, it makes a bit of a buzz. When I turned the potentiometer and the motor shaft started turning, it felt like MAGIC!
- I ran the motor for a 5 minutes and made sure the wires didn't get hot.
- After I was confident I wouldn't burn anything down and that this set up was going to work, I decided to mount the motor underneath the bandsaw.
Step 5: Mount Your Motor Underneath the Bandsaw
Mounting the Motor was more difficult than I thought just due to the space constraints and making sure that you have the right size belt. After doing this a two times (see attached picture for reference), I learned that it's really about two things:
- Make sure the pulleys are inline so the belt can be plumb: You can also move the pulley on the shaft to adjust this easier but something to keep in mind is that it's best if you can keep the pulley closest to the bandsaw or to the motor.
- Bolting the motor to the right elevation: I ordered the V-belt correct once (I aligned the pulleys, and used string to measure the pulley size) and It was pretty easy, but I also ordered the wrong V-belt size and had to make it work with scrap lumber even thought these V-belts are relatively cheap. After doing both methods, I don't think it's all that bad to use scrap lumber to get to the correct size and even adding some adjustability to the mount will make it easier to change belts as well.
Disclaimer: I'm sure there are better ways to do this but as far as performance goes, just make sure the belt is tight enough to rotate without slipping and I think it's fine.
Step 6: Start Using Your Bandsaw With Variable Speed Control!
Once I started using a bandsaw with variable speed my curiosity has been increased in both bandsaws and motors. I'm not quite done with either of my bandsaws but I'm learning a lot and hoping more people can get into upgrading and modifying bandsaws to do interesting things along with upgrading other equipment. Below are some of my thoughts:
- The expensive part of these machines is the VFD. I think I can use a 220v twist lock plug to connect the VFD to different motors as long as they’re the same power rating (HP or watts, 745.7watts = 1hp). This way I can use different equipment powered by one VFD and plug into the VFD into different machines as long as they run on the same horsepower.
- Having variable speed on machines is a dream. I like the soft start, the quick adjustments that can be made with a potentiometer along with the smooth running nature of the motor is nice.
- I went Super Nerd on acquiring these motors and old bandsaws. I definitely went too deep into motor and motor control but at the same time, my level of understanding is novice. There is so much more to get into with speed control along with different types of motors like stepper, servo, and permanent magnet motors.
- The main problem that I see now is that I'm no longer complacent with the prices I've paid for machines with single speed, capacitor start motors. These machines feel dumb to me and I'm frustrated by the lack of innovation that we have had for the prices we pay.
If you got this far, Thank you for reading and I hope this encourages more people to venture down the variable speed motor control rabbit hole for old tools. Feel free to ask me any questions!
Participated in the
Make it Move Challenge