[kolias]

I’m building a bandsaw as a hobby from a YouTube video which I modified to suite my needs. Most if not all the videos I have seen have two wheels but I want to used 4 wheels as per attached picture (2 wheels of 6”OD + 2 wheels of 1.5”OD). I have no experience with bandsaws and I wonder if it’s a bad idea to use 4 wheels instead of 2 wheels.

If successful it will be used for homemade crafts.

 

[PhilBa]

All the wheels will need to be aligned so the axles are parallel. This is why 3 wheel bandsaws are harder to keep properly set up. 4 would only make it worse.

 

[difalkner]

I would say the alignment difficulty goes up exponentially with each wheel past two. But maybe you'll get lucky and it will work. If there's a way to do it with just two wheels I think you'll like and use the saw a lot more.

David

 

[kolias]

Now I understand the popularity of the 2 wheels and I agree. I will give it a try and if not successful (most likely I will not be!) I will switch to the 2 wheels.

To keep the same frame I figure I will need 7”OD wheels and the max. width of my cuts will go down to around 6.7”.

My thanks to both

 

[TenGees]

Another possible issue: Your two extra wheels are kinda small in my opinion. They could stress the blade more, bending at that radius.

 

[kolias]

Good point Paul but the min. radius for this thin scroll blade is 1/4” (blade is 59.5” long, 15TPI)

 

[sreilly]

Interesting project. Please post as to the final outcome and results.

 

[TenGees]

Wow 1/4" radius seems very small.

 

[sunnybob]

Good point Paul but the min. radius for this thin scroll blade is 1/4” (blade is 59.5” long, 15TPI)

You misunderstand, that quoted radius is of the CUT in soft wood. NOT the amount of side bend you can put on the blade.
The blade will break, again, and again, and again.
4 wheels... DOOMED to failure. (Theres a good reason why nobody in the world makes a 4 wheel bandsaw)
3 wheels... there are three wheel bandsaws, but they are notoriously difficult to get running properly.
2 wheels... theres a reason 95% of bandsaws have two wheels.:wink:

 

[gmercer_48083]

You misunderstand, that quoted radius is of the CUT in soft wood. NOT the amount of side bend you can put on the blade.
The blade will break, again, and again, and again.
4 wheels... DOOMED to failure. (Theres a good reason why nobody in the world makes a 4 wheel bandsaw)
3 wheels... there are three wheel bandsaws, but they are notoriously difficult to get running properly.
2 wheels... theres a reason 95% of bandsaws have two wheels.:wink:

I agree... The small wheel radius is like bending a paper clip over and over until it breaks. The blades are doomed. Consider how many flexes the blade has to make per rotation.

 

[PhilBa]

Wow 1/4" radius seems very small.

'tis. I'm pretty sure that's the radius of a cut, not the bend.

 

[thomas1389]

Aside from alignment difficulties, if a 4 wheel setup was necessary couldn't you reduce the stress on the blade by moving the two small idlers closer to each other and closer to the large wheels. The blade would still clear the centre opening, just closer to it.

 

[Nickp]

Nicolas...if your objective is a bigger throat opening, I suggest you make yours with bigger wheels and only use the usual 2-wheel configuration. Those smaller idlers will give you plenty of headaches as has been noted already. The brand name saws have extensive alignment requirements to run correctly...co-planar wheels, some with non-coplaner wheels...it all depends on the manufacturer. If you have a moment, check out "Alex Snodgrass' bandsaw clinic"...you'll get a pretty good idea of what you're up against with a 4 wheel configuration.

With 4 wheels you will need a way to align each wheel, otherwise your blade will go off-track when entering the upper wheel. You will not be able to align the blade on the two big wheels without being able to align the idler wheels...

Make bigger wheels and use only two...you'll get a bigger throat opening and eliminate all the alignment issues...

 

[kolias]

Nicolas...if your objective is a bigger throat opening, I suggest you make yours with bigger wheels and only use the usual 2-wheel configuration. Those smaller idlers will give you plenty of headaches as has been noted already. The brand name saws have extensive alignment requirements to run correctly...co-planar wheels, some with non-coplaner wheels...it all depends on the manufacturer. If you have a moment, check out "Alex Snodgrass' bandsaw clinic"...you'll get a pretty good idea of what you're up against with a 4 wheel configuration.

With 4 wheels you will need a way to align each wheel, otherwise your blade will go off-track when entering the upper wheel. You will not be able to align the blade on the two big wheels without being able to align the idler wheels...

Make bigger wheels and use only two...you'll get a bigger throat opening and eliminate all the alignment issues...

Thanks Nick for the heads-up, the Alex Snodgrass' bandsaw clinic has a pretty good and useful info on my subject.

It’s true the idea was and is to have the max throat opening, not because I have a need for it but since I make a bandsaw from scratch why not?

As I mentioned I have scraped the 4 wheels setup and I already cut 2 new wheels 7.5” OD which will fit in my present bandsaw frame. All this work is experimental and if all works well I may make a new frame later on which will better fit the 7.5” OD wheels.

 

[Nickp]

Thanks Nick for the heads-up, the Alex Snodgrass' bandsaw clinic has a pretty good and useful info on my subject.

It’s true the idea was and is to have the max throat opening, not because I have a need for it but since I make a bandsaw from scratch why not?

As I mentioned I have scraped the 4 wheels setup and I already cut 2 new wheels 7.5” OD which will fit in my present bandsaw frame. All this work is experimental and if all works well I may make a new frame later on which will better fit the 7.5” OD wheels.

Good to hear, Nicolas...good luck with the build. We remain anxious to hear the results...

 

[kolias]

Since I basically re build the bandsaw, in the attached sketch are the bearings layout acceptable?

Also in the second picture, is this a good way to square the shaft to the wheel?

Thanks

 

[PhilBa]

The problem with that is you have to get it perfect. Most bandsaws have a way to adjust the angle of the axle. That's how tracking is adjusted. Typically, the top wheel is mounted on a ring that is not hard connected to the frame and can be adjusted so the angle of the axle can be adjusted. In your case, the square plate would be adjustable.

Another complicating issue is you need to be able to adjust the blade tension (essentially the distance between the wheels).

 

[kolias]

Phil perhaps you misunderstood, but both of my pictures refer to the LOWER wheel. The top wheel will be as you describe including the tensioning of the blade

 

[sunnybob]

I think you dont understand the sideways force that will be on the bottom wheel when you tighten the blade.
That wooden wheel will tilt out of that bearing shaft on the first use.

If youre going to re invent something that has been around for well over a 100 years, youre going to have a lot of failures.

Try following the expert;
https://woodgears.ca/bandsaw/

 

[kolias]

Guys I don’t try to re-invent anything, in my post #16 I was asking for suggestions on how to install the bearings and instead I’m getting more questions.

I’m aware of the woodgears site, an excellent site by the way, and I see how he installs the bearings on the wheel but he doesn’t show how the bearings are installed on the body of the bandsaw.