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16 inch Bandsaw - Wheels

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2019-01-19
Small bandsaw

Surprise: I already own a bandsaw! :-)

It is one of those small 3-wheel machines, which Matthias doesn't like very much - and he is right, it is not very accurate and it breaks quite a few blades. But it only cost me 25 euros, and it did convince me that I like owning a (better) bandsaw, so it is the main reason I'm building a new one. So if you are not sure about building a bandsaw, get a cheap one like this and see if you like them.

And it comes in very handy during the build, as you will see further on.

I have hooked up a (very) makeshift shopvac attachment, which helps a bit but is of course not very effective. I'm planning to add a more permanent kind of shopvac attachment to the new machine, but that will have to wait until it is finished.


Wheel glue up

Glue up of one of the wheels, made out of leftover pieces of MDF, 18 and 12 mm sandwiched together.

I drilled 6 mm holes in the center and where the 4 bigger holes will be situated, and used some bolts for extra clamping power.


Pulley on the router

I made the temporary pulley from some pieces of leftover plywood, and cut it roughly to size on the bandsaw, and then rounded it more precisely on my workbench (which has a router built in).


2019-01-20
Pulley groove

I made the groove on the tablesaw (blade set to 17 degrees for the V-belt), and it turned out very nice. So maybe I will use it as the permanent pulley later - if I can attach it precisely enough. [Note: I did use it as the permanent one]


2019-02-08
Turning the wheels Crown

My setup for turning the wheel, and putting a crown on it. The dust collection is very much needed for MDF.


2019-02-17
Balanced

Balancing the wheel was so simple it was almost disappointing. I just had to drill one small hole in the bottom wheel, the top one did not need any adjustment. So making the wheels out of MDF turned out to be a good idea; the plywood pulley was probably the only cause for imbalance.

As you can see I opted to glue and screw the flanges to the wheels. That was a lot easier than trying to just glue them on while getting the alignment right at the same time.

Small tip: You may want to make the holes in the wheels a bit bigger than the 4 cm indicated by the plans. I had a hard time getting my clamps to fit through them.


2019-02-22
12 inch tire

The local bicycle shop only had one 14 inch tire in stock, so I picked up a 12 inch one as well, thinking I'd probably be able to get it on. Turns out it fits even better than the 14 inch; the 14 inch is a much looser fit so the sides are more likely to catch sawdust. It was a bit of a struggle to get it on though, but manageble. So I'd recommend using 12 inch tires.


2019-06-09
Wheel wobble

The top wheel turns out to have a slight wobble, which I missed earlier (or chose not to see, not sure...). Nothing serious, but it does cause the whole machine to wobble a little bit, which is not ideal. So I'll probably make a new wheel later.

The ruler is in centimeters, so the gap is slightly more than 1 millimeter.


Part 2

2019-08-16
New wheel

Glue up for the new top wheel.

And the new one (number 3) had a wobble as well... Maybe I abused the bearings too much (in my original attempts to fit those to the shaft, which was a tight fit), or using 4 pieces of leftover MDF instead of just 2 was not such a good idea, or the plywood that holds the bearing is just too crummy, or all of the above. Anyway, while turning the crown on the wheel, I also turned a bit off of the sides of the wheel to remove the wobble at the outer edge. This turned out great - so great in fact, that now you only notice the (much smaller) wobble in the bottom wheel :-)

So I will probably remake both wheels, with new bearings, better plywood, and 2 pieces of MDF. Also, I will remake & resize the pulleys (and order a larger V-belt), to reduce the blade speed. More to come!


Part 3

2019-09-07
Circle cutter

Starting work on some new wheels once again, numbers 5 and 6 this time. Numbers 1 through 3 you know about already; number 4 was a total mess during glue up, I won't mention that one again, too embarrassing :-)

The circle cutter always tries to hit your hands when drilling into smaller pieces of wood (yes, it happened to me, and it hurt). Screwing down the pieces for the wheelmount like this worked perfectly; I should have thought of that before... Even better, leave the four pieces as one board, cut the holes, and only then cut it into the four pieces themselves. I did that later for wheels 7 and 8 and that works even better.


2019-10-01
36cm pulley

I did some calculating to determine what size pulleys and v-belt I would need to reduce the blade speed as much as possible. A formula for that can be found at https://bepltd.com/pages/how-to-calculate-belt-length for instance; playing around with that in Excel gave me a nice idea of what was possible.

At the moment the pulleys are 93mm and 284mm in diameter. There is 284mm distance between them, giving a belt size of 47 inches. This resulted in an RPM range of 134 to 537, and an FPM range of 550 to 2200.

A pulley size of 360mm is as large as will fit without getting in the way of the tire (see photo), and I didn't want to modify the motor mount so the 284mm distance is fixed as well. With that in mind, I came up with this:

The new pulleys will be 70mm and 360mm in diameter. With the same 284mm distance between them, which gives a belt size of 52 inches. And that should result in an RPM range of 80 to 320, and an FPM range of 330 to 1320. Since the belt size and the distance between the pulleys are fixed, the pulley sizes may change a bit to get it all to fit.


2019-10-04
New pulleys

I finished the new pulleys, and they work like a charm. The calculated sizes were almost perfect, I just had to reduce the size of the smaller pulley by 10 mm to get it all to fit.

The result: an RPM range of 78 to 315, so an FPM range of about 320 to 1300. Perfect enough :-)


2019-10-05
Bearing Gap Wheels 4, 5 and 6

I'm not having a lot of luck with the wheels - numbers 5 and 6 have turned into a failure as well... But at least now I know why these failed (and also why number 3 failed): the circle cutter can be easily misaligned (or misaligns itself over time, not sure), which results in holes that are wider on one side than the other. So while the bearings do seem to fit fine, they are only clamped by half of the plywood at most, and so they work themselves loose over time, which explains the wobble issues. Sigh...

I don't feel like making 2 more wheels at this time, so I've decided to mount the new pulleys on the existing wheels, and call it quits on that subject - at least for the time being. For a next attempt, I might go for a Forstner bit (although I have yet to find one that is 52mm wide - 51mm is the closest, which might work) or a Small Circle Cutting Router Jig like the one shown in https://www.youtube.com/watch?v=PsV-84kjnVY.


Part 4

2020-05-31
Starting attempt 7 and 8 Getting to 52mm

After ignoring the small wobble for a few months, I decided to start another wheel build (numbers 7 and 8). For the 52mm hole for the bearings, which caused most of the earlier problems, I now tried a simple (and cheap) 51mm (or 2 inch) hole saw. I haven't seen any 52mm options - and those may have been slightly too big anyway - so I went for this. For 9 euros for a complete set, it was worth a shot.

And it works! The holes do need a bit of sanding/grinding to make them a bit bigger (see the photo for what I used), but that's easy enough. And the bearings seem to fit very nicely indeed. I also use baltic birch plywood this time, which may help a bit. Drilling the four holes in one larger board, before cutting the four flanges to size, makes drilling a lot easier.


2020-06-09
Even more holes

I plan to make these new wheels similar to the ones Marius Hornberger made for his version of this bandaw. So with more holes (no real use to me but it looks nice) and a different design for the crown on the wheels, to prevent dust from collecting under the tire. See his video on Youtube for more info.

I also used a tip I saw on Youtube recently (can't remember where) to prevent overheating the holesaw, by brushing off the sawdust every few seconds, and that works like a charm. No more burnmarks!


2020-06-14
Lathe work Crown with rim

(Mis)using the lathe and my previous set of pulleys to turn the wheels and the new style crowns.

One of the wheels had a very small wobble (<1mm), so I just ignored that. The other one had a wobble of about 2 mm, which was (again?) caused by warped MDF. Sigh. So once again I turned a bit off the sides of the wheel to remove the wobble at the outer edge, which should solve most of the issue.


2020-06-19
7 and 8 all done

And there we have it - wheels number 7 and 8 all spray-laquered, balanced (hence the neat row of screws in the bottom wheel) and mounted. They run a lot quieter and more stable than the previous ones (almost no wobbles anymore!), so these should be the final ones. Finally...

I spent quite some time on getting the blade (and the blade guide) square to the table. The new wheels are slightly thinner than the previous ones (and probably have a slightly different diameter as well), and that puts everything slightly out of alignment. So now the frame next to the upper blade guide has 2 new shims (some layers of gaffer tape this time, very handy stuff), the table has a new plastic 1mm shim (left-right adjustment) and the table mount has a plastic 0.5mm shim (front-back adjustment). Quite some fiddling to get that right, but now everything is square once again.

A few tips:

  • I used 12 inch tubes, which work fine. Just don't cut them to their final width right away - stretching them over the wheel also makes them less wide so allow a few milimeters extra for that.
  • Don't tighten the locking screws on the end of the shaft too much - I found that the extra pressure on the bearing made the wheel turn a lot less easily.
  • I used two layers of 15mm MDF this time, instead of 12mm and 18mm - shouldn't make a lot of difference, but the fact that the "join" is now exactly in the middle of the wheel might have some impact on stability. And it looks nicer :-)
  • Since I screwed on the flanges anyway, I now used a minimal amount of glue. So no glue squeeze-out this time, which looks much nicer.