A couple things before we get to the fun stuff:
The following worked for me and I was comfortable with the procedures. I am in no way responsible if you do something outlined in this article and hurt yourself or your property in any way.
Please understand the power of the motors we’re working with here – they are nice and quiet and seem harmless, but they will rip your hand off your arm in a heartbeat. Don’t ever forget it.
I’m also no engineer. I researched pretty heavily and made sure I knew the equations, but everything below amounts to little more than a lay-man’s conjecture. Please don’t get too bent out of shape when I confuse power and energy :-p
[Edit: I realized I wrote a blasted book here, sorry about that! Should have more than enough info for anybody wanting to attempt it themselves…]
Ridgid (the Home Depot) brand has been making a band-saw for a number of years. It is a modest 14” machine with cast wheels, cast iron table, 3/4HP motor and about 5” of re-saw capacity. At the time I purchased one, it ran just about $400.00, which is a reasonable price in this space.
There have been minor revisions to it over the years, tweaking aspects of it here and there, but it’s remained largely the same for a while now. If you wanted to dive deep on the thing, you’d find out that it is actually the same saw that is marketed variously as a Grizzly, Porter Cable and Delta.
Strictly speaking, this is not a bad band-saw. With a little effort it will run pretty smooth on the stock components and it will cut decently with a sharp blade.
There are a number of very common and inexpensive after market accessories that many people add to these saws. Among them are urethane tires, link-style drive belts and better blade guides. These bring the vibration under control and will increase the cut quality.
In my opinion, none of these address the fundamental problem of this saw, and most saws in this space: power.
This saw is quite under-powered for cutting in anything 8/4 or thicker, at any reasonable feed rate. The motor simply bogs down at what I would consider normal feed rates in various materials.
Assuming all materials being equal, a number of factors go into how easily a saw will cut and how fast you can feed the material. Blade tooth spacing, blade speed (in surface feet per minute), motor power – all factor in.
Many people will wax poetic that a 3/4HP motor should be more than enough if you feed slowly enough. I guess there is some validity here, though on this saw in order to re-saw the full ~6” inches, the feed rate must slow to the point that the cut heats up enough to burn the material – and dull the blade. So feed rate clearly isn’t everything.
In my expierence, it all starts with blade speed. The blade must be moving fast enough to clear the chips from the “previous” cut so the next tooth can start its cut. As you feed material into the blade, the blade will slow down. How much it slows down is (for our purposes) a function of the feed rate and the power driving the blade. Other things factor in, but these are the big ones.
In order to keep blade speed up, the motor driving the blade must be able to pull the blade through the material at a constant rate without bogging down due to the cut.
This self-perpetuating cycle is what kills this saw; The cut starts with the blade at full speed, it slows down as feeding begins, this slows the speed of chip removal, which decreases cut efficiency, which further loads the motor, which slows down the blade further…. I think you get the picture.
I set out to fix this issue.
Stock configuration: Wheel Diameter: 13 5/8” Motor RPM: 1725 Motor HP: .75HP Motor sheave: 2 5/8” Wheel Shaft: 7/8” Saw sheave : 6” Current blade speed: 2,691SFPM
A blade speed of 2,691sfpm is not exactly screaming. I can only guess that the blade is moving at this speed in order to accommodate some metal cutting. As I never cut metal, I want the blade sped up. My goal was about 3,500sfpm. This is a significant increase, without being a multiple of the original. I wouldn’t go much faster on this saw for fear of prematurely wearing out the cheap Chinese bearings in the wheels.
I happen to have a nice cabinet on wheels, with a 3HP 220V motor already mounted in it from an old jointer. It was all wired up with a switch and everything. I decided to simply transfer the band-saw from its old steel stand onto the home-made stand. You can see in the pictures the cutouts from the previous jointer’s chip ejection. The cabinet is build out of doubled up 3/4” ply and reinforced at the corners. It is more than strong enough for the band-saw.
The biggest obstacle I ran into was getting the blade to the speed I wanted it. The motor was a 3,450RPM motor. If I had simply used the stock sheave sizes, it would bring the blade speed to something like 5,300sfpm, which I was pretty sure would overtax the machine.
I already had a 3” sheave on the motor, and being both cheap and lazy, I decided to leave it and then size the wheel sheave accordingly.
With a 3” drive sheave and a 13.625” diameter band wheel, in order to hit my blade-speed goal, I needed a wheel sheave about 10” in diameter. Luckily Grainger had a 10.25”D Cast Iron vbelt sheave on clearance. $30, shipped! With the large motor, the added weight of the cast-iron sheave will help keep the blade moving through the material.
A quick bit of math says that this configuration should result a blade speed of 3,600sfpm on the nose. Bingo!
If you don’t want to crunch the numbers yourself, you can use this great online calculator: http://vintagemachinery.org/math/sfpm.aspx
With the grub screw loosened, the stock drive sheave slipped off without having to break out the gear puller. I had to file down the shaft pin in order to get the new pulley on, but it didn’t take long. Before drilling the holes for the through-bolts that would hold the saw to the stand, I went to great efforts to be sure that the drive and wheel sheaves were in line, co-planer and all that happy stuff. Once they were, I bolted down the band saw and took a measurement around both sheaves to determine the belt I needed. The local auto-parts store had a 69” V belt in the style of my sheaves for $15. A couple of test runs without the blade to be sure it all wouldn’t explode. Hooked up a new blade (3tpi), aligned and tuned everything and off to the races!
Let me tell you, the thing is a monster. I can feed at a rate that’s probably faster than I’d ever safely want to go. I tested it out by “re-sawing” a 2×6 I had sitting around and I literally couldn’t push it into the blade fast enough to noticeably bog the motor or slow the cut. I took the corners off a couple 5” thick hardwood bowl blanks and the saw acted like it was cutting foamcore. I couldn’t be more pleased.
Final Configuration: Wheel Diameter: 13 5/8” Motor RPM: 3450 Motor HP: 3HP Motor sheave: 3” Wheel Shaft: 7/8” Saw sheave : 10.25” Resulting blade speed: 3,600SFPM
Now that it’s actually got a surplus of power, I’m going to look into a riser block. They word on the street is that the 6” kit for one of Grizzly’s saws will fit the Ridgid without much modification, so I may go that route. It will obviously necessitate a new blade, so I may get something a little higher quality at that point too.
The cost point of this, for what I gained, made sense for me. Specifically because I already had the motor and switch.
Here’s a general breakdown of the costs I incurred here:
Plywood for cabinet: $40
Angle Braces: $5
4 Swivel lock casters (nice ones): $50
69 inch 4L v-belt: $16
3” motor pulley: $10
10.25” wheel pulley: $30
Some 10/3 extension cord: $25
Various screws, doodads and fasteners: $10
3HP Motor (Grizzly): $300
Thanks for reading!