Modify A Small Band Saw Homemade Machines & Jigs
About a year and a half ago I bought a small band saw, mainly because I had to make a lot of small parts at that time and didn’t want to outfit my big band saw with a thin blade. The big one is set up and more suitable for making heavy rip cuts and resaws – the table is too low to work at intricate parts for extended periods.
I don’t make many impulse buys, but buying this saw was one. I briefly looked it over in the store, and without much more thought, bought it. Given how little it cost, it appeared to be reasonably well made. The frame was solid and the blade tracked well. The tension and tracking mechanism looked to be well designed. The motor was undersized, but that is the norm with these cheaper tools.
Putting it together revealed its deeper problems, and at that time I should have returned it. Of course, stupidly, I did not.
Top of the list of problems was the table and trunnion system. The casting and machining on both were very poor and the table could not be installed square to the blade – I had to shim it. The knob that locks it in place was very small and awkwardly placed, making it very difficult to tighten it enough to hold it’s position.
Also, the upper blade guide was poorly machined and used a rack and pinion to lift and lower it. The blade guide was not mounted parallel to the blade and I had to ream out bolt holes to line it up to the point where it wasn’t deflecting the blade sideways as the guide went up. Maybe if more effort were put into the basic fit and finish of these machines, and less on useless “refinements” like rack and pinion height adjustment, they would be worth buying. Isn’t that the way things used to be?
Speaking of useless, it came equipped with the ubiquitous laser. Seems no tool these days makes it through design and production without having one of those pinned on, somewhere.
It blows out my dwindling faith in humanity when these doodads actually do what they are designed to do: attract an ill-informed buyer.
The motor is rated for a full load current draw of 2 amps, which equates to about 1/8 HP. This is not enough power for this type of tool, if you are actually going to use it. It would stall regularly and wouldn’t start on its own on cold days in my shop – I’d have to open the upper door and give the wheel a spin. Seriously.
Ok, it’s not all bad and here are some of the things that impressed me. First, the frame. Solidly made from thick steel, it requires no stiffening. All of the welds are very good and the upper and lower parts are very nearly perfectly in line with each other. Nothing fancy, just good material choices and workmanship.
The wheels are good as well and look to be very well balanced. They are cast aluminum and the casting looks to be competently done. The hub on each has two sealed bearings that are pressed in place.
The blade tension and tracking is simply done (I should have seen this one before I made the one on mine) and works extremely well. The lock on the tracking is very firm and holds well.
It has a light on a flexible arm that is handy, but is positioned at the rear of the saw. Moving it to the front would be an improvement.
The first step was to strip off all of the parts and wiring. Here, I’ve removed the doors as well, so that they won’t be in the way during the rebuild:
A look at two more trouble areas. The lower blade guide that can’t be adjusted over far enough because the thrust bearing contacts the frame:
and lower wheel adjustment bolts, the bottom one is drilled off centre and has bent.
The motor is removed. The stock belt is flat v-grooved and pulleys are plastic:
The larger pulley was mounted on the lower wheel with three screws. I didn’t measure, but the reduction appears to be 2:1, giving a blade speed of roughly 2000 fpm.
Now for the first tricky operation. I need to make a new pulley to go on the lower wheel and I figure solid hardwood is the best material I have for this. I cut it to rough shape, lay out the centre lines, mount it in the lathe and make it round:
I used a v-belt to check the size.
I made a short video of it:
This pulley has to fit into the hub on the bottom wheel just like the stock pulley does and I machined it to fit on the lathe. I then drilled out the centre with a 1″ bit:
To clear the bearing hub, I used a bevel bit in the router table to cut back the opening.
It fits very well on the lower wheel:
To attach it, I mark and drill 5/32″ holes and tap the wood for #10-24 screws:
The screws are coated with polyurethane adhesive before driving them in. I don’t want these screws to work loose.
An improvement to the lower wheel adjustment arrangement is to grind flat spots on the shaft end, for the bolts to bear against:
Putting the locking nuts inside the cage increases support and prevents the bolts from bending.
The new motor will be mounted beneath the saw, in a stand, and I had to cut a hole through the bottom for the v-belt to go through:
The wheel is mounted with the new pulley attached. I painted it to seal it from moisture migration, although I don’t think this will be an issue.
The motor mount:
3/4″ plywood and two 3″ butt hinges.
Much of this build is for testing out ideas, and I really didn’t have a written-in-stone plan going in. Experience has taught me that when you are doing things this way, you’ll make a mistake or two, and it’s best to not use “the good stuff” to build it with. I have a lot of leftover scraps from various projects and put them to good use here.
I mounted the shelf where the motor is according to the v-belt that I had, clamped the motor down and fired it up.
Good to do a lap or two before the race to weed out any problems. I found one. I had a 6″ pulley on the motor and the 4″ on the lower wheel, thinking with some extra power I could run the blade speed up too. Maybe a bit too fast – centrifugal force pulled the tire off the upper wheel:
It seemed prudent to slow it down a bit, so I put a 3″ pulley on the motor. Quick calculation puts the blade speed at 3130 fpm (double that with the 6″ pulley!) which seems to be about right. Of course, I had to smash out that shelf that the motor was on and move it down for the new, smaller pulley. I could have bought a shorter v-belt but decided to go with what I have.
Since I have a bigger motor, with more power than the saw really needs, I thought it might be interesting to build in dust collection. I made an impeller from plywood.
The vanes are glued with polyurethane adhesive and screwed from the back:
At the rear of the stand a chamber is formed for the dust collector.
I laid out the shape for the housing and cut pieces of melamine to fit around it:
This is not optimal, but should develop enough airflow for the task.
The back is closed with a 3/4″ panel:
The dust collector is something I will continue working on to increase the airflow through.
The new thrust bearing for the lower blade guide:
Simple enough. The tabs that are sticking up from the frame will be cut off, as the new table sits flat on this surface.
The upper blade guide:
Made in the same way as the one on my big band saw. It uses the UHMW plastic for guide blocks that have worked so well on my big saw.
The mounting for the upper blade guide is done in the same way as on my large band saw. Solid hardwood blocks with 1″ holes drilled through and bolted on:
I have found this to be a very reliable and easy to adjust system. No rack and pinion required.
I reused the switch for the light and had to splice the connector that fit on it into the new wire. I like to solder these joints then two layers of heat shrink over it.
For the main power switch, I have this size fast-on connector, so I just used it on the end of the new wire:
I solder these as well, after crimping and insulate with heat shrink.
A 4″ x 4″ box is used to junction the wires near the motor. All of the wires are stranded, so I took the time to tin them before wire nutting them together:
It takes a little more time to do this right, but well worth it for the peace of mind it provides.
On the first test of the dust collection, I found that too much was landing in the motor compartment, so I made a baffle to fit:
Notched around the v-belt and it works well to direct the dust to the port.
Here’s something I should have done earlier, while the saw frame was still stripped down:
The 1-1/4″ hole is better than nothing, but I will eventually cut out the entire inside corner.
The new table does not tilt and I came up with a simple way of installing the UHMW plastic guide blocks:
Works well. I may make the table tilt at a latter date, at which time I’ll have to redo the lower blade guide. I find the about 99% of the cutting is done at 90 degrees, and the rare time I need to cut at an angle, a ramp black can be made very easily, like I used to cut the helix gear for the worm drive.
The dust collects in a box in the bottom of the stand. It has a piece of an old T-shirt as a filter on one side:
This works well and the filter seems to be the right size.
I made a video of the saw and it shows it in action:
Overall, an interesting project. It’s always a good thing if you can improve a tool to make it more productive. I believe the time spent to modify the saw was worth it, since it works so much better now and I will definetly be using it more.