Making blade guides for my 26" bandsaw
The guides I want to make for this bandsaw are the same as the guides on my 20" bandsaw. I'm pretty happy with that design, so I'll use it again.
The upper and lower blade guides both have this block with a notch cut out of it behind the guide blocks. I cut a piece of hard maple big enough for both blocks in one piece and am cutting the notches on my table saw using a table saw sled.
Notches cut, now marking the locations of the holes for the bolts that hold the guide blocks. I could use the templates for this, but it's just as easy scratching lines on the wood with a set of callipers using the dimensions on the drawings.
Then using a tap in a drill to cut threads in the holes. I'm using a 5/16" tap (roughly M8), though in my plans I have this as 1/4" (roughly M6), but the bolts I had were 5/16, so I'm using that size.
With all the holes drilled, cutting the piece apart to make two blocks.
If you don't have any high quality plywood such as baltic birch, I'd recommend making this block out of solid hardwood instead.
I need a slot in the side of this block. I drilled three 5/16" holes side-by-side, then drilled in between them to hog out more of it. Drilling between holes is tricky even with a forstner bit and a drill press. If you don't have either, don't try to do this and just clear the slot with a chisel.
After tapping and drilling that hole, I need to cut a slot through it. This slot allows the block to clamp down on the bolt that goes in the hole I just threaded when it's clamped down against the guide post.
I need to mount a ball bearing on a bolt. I'm using a carriage bolt for this because it has big flat head, but I need to be able to turn this carriage bolt with a screw driver, so I cut a slot in its head with an angle grinder (see picture at right)
When drilling holes in metal, it's usually easier to drill a small pilot hole followed by the actual size hole. The center of larger metal drills don't cut very effectively, so if the center is already drilled out, much less downward pressure is needed while drilling.
I'm making the guide blocks out of some lignum vitae, which is the hardest wood I know of. But any exotic wood would do. In fact when I built my first bandsaw 11 years ago, I just used hard maple soaked in oil. I had to sand those guide blocks flat on occasion from wear, but the guy who bought the saw from me back in 2018 reports he's still using the original guide blocks!
And once those guide blocks do wear out, it's not difficult to make new ones!
This completes the upper blade guide.
My slot mortiser would do a much better job of cutting these slots, but I wanted to show that you don't need my fancy tools to make this bandsaw.
And mounting another ball bearing on a carriage bolt for the lower thrust bearing. I had some lock washers that fit inside the bearing and around the bolt to help keep the bearing centered on the bolt. Another washer behind the ball bearing offsets it slightly from the wood so it doesn't rub against the wood as it spins.
I would have preferred to use the same kind of allen key screws on the bottom as I used on the top, but I ran out. So I used regular hex-bolts instead.
Now I need to mount the blade guides. The top blade guide mounts to a column that can be adjusted up and down. At left, the column from my 20" bandsaw, with the metal blade guard attached. At right, the blank for the guide column on my new bandsaw.
You can also see towards the right of the notch that I left a bit of extra material, a bit of a ridge, so to say.
With the notch fitting around the tab, this prevents the front of the block from dropping down, especially when the blade guides are moved forward a bit.
The guide body is attached to the guide column with a bolt through both. I'm using a "jig bolt" here because I have lots of those, though a hex bolt or carriage bolt would work as well, as long as you cut the right shape of cavity to recess the head.
I also measure how far from the frame to the center ridge (crown) of the wheels. The blade is usually tracking right on top of that ridge or crown.
I also measured how deep I need to cut the notch. With the blade guides blocks adjusted all the way back, the front edge of the blade guides should be as far forward of the frame as the center ridge of the wheels.
When I built my 20" bandsaw I glued the piece of threaded rod into the frame with construction adhesive. But once one of these tubes of glue is started, the rest goes bad soon after. So this time I just screwed the threaded rod into an undersized hole.
I cut a big notch in the front of the threaded rod to act as a sort-of thread cutter, then just screwed the rod into the hole with my drill.
If for some reason this won't hold, I can always glue it back in with construction adhesive later.
Last time I found it tricky to glue this bevelled piece on, so this time I glued on a square piece and cut the bevel with the table saw afterwards, though making this cut is not the safest thing to do.
If your table saw is a left tilt saw (as most are), you will have to make this cut on the right side of the fence.
Another piece of wood with a rectangular notch in it goes against the back edge to keep the block from sliding forward. That way, when the block is tightened down with a knob on the threaded rod, it pushes the guide post diagonally into the notch in the frame, making contact on the side and on the back.
The lower blade guides will mount to the trunnion support beam, which I haven't made yet.
Also trying a bit of resawing, but with just a 1/4" blade. I have a wider blade, but without any guards on the saw, I prefer to stick with the thinner lighter blade, just in case it might come off.
And finally, checking resaw height. The final table will be thicker and higher, so I measured from a piece of 2x4 lumber on my table to the blade guide in it's highest position. I have 38 cm, or 15 inches. So the final maximum resaw height should come close to that.
Trunnions for the table (2021)