Why no 3-wheel bandsaws?

A simple question: why aren't bandsaws more commonly made with three wheels instead of two? Sure, I've seen custom jobs made that way, and the fact that 2 is more simple than 3 is obvious, but the tradeoff for cutoff and height capacity seems worth it, but I don't know of any popular manufacturers making them.

There must be a good reason...anyone know?

Curiously, H

Reply to
Hylourgos
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ISTM it's harder to get three wheels in the same identical plane as two. I think that's the primary issue.

-- Mark

Reply to
Mark Jerde

Blade fatigue is the big reason-in addition to manufacturing expense.

Greg G.

Reply to
Greg G.

Why would there be blade fatigue if you used the same diameter wheels? All the 3-wheel bandsaws I've seen use smaller wheels but ISTM this is a decision, not a requirement.

-- Mark

Reply to
Mark Jerde

good question. I just checked in "Bandsaw Handbook" by Mark Duginske. He said that early 3 wheelers had small diameter wheels that stressed the blades. He mentions that even with larger wheels the blade life is shorter. No explanation of this phenomenom is given.

dave

Mark Jerde wrote:

Reply to
Bay Area Dave

On 13 Jan 2004 20:36:15 -0800, snipped-for-privacy@sewanee.edu (Hylourgos) brought forth from the murky depths:

From what I've heard, the blades break every dozen revolutions or so due to the small wheels and tight radius. It stresses the metal too much for longevity.

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Reply to
Larry Jaques

I made it to 2/3 rd's of a Mechanical Engineering degree before switching to Computer Science. The only possible explaination I can think of in 4 minutes of cerebration is that the number of bends per blade revolution is significant. Suppose you had two bandsaws, each with 15" wheels. One has two wheels, the other 3. The two wheels model would subject the blade to two bends per revolution. The three wheeled bandsaw would have 3 bends per rev of the blade. Maybe it is not so much how long the blade is curved around the wheel but how many times you change its straightness. The answer is beyond my knowledge one way or the other.

-- Mark

Reply to
Mark Jerde

Every time you bend the blade around a wheel, it results in fatigue. Eventually, the constant bending and straightening of the blade results in breakage.

Greg G.

Reply to
Greg G.

big 3 wheelers have a big footprint. they have to have a much stiffer frame. the tighter radius is hard on the blades.

Reply to
Bridger

I have both, though the 3 wheeler is for sale. The 3 wheeler goes through blades faster, due to stress of smaller diameter wheels and thinner baldes but has always tracked OK,even after 16 years of (ab)use...

2 wheelers are cheaper to manufacture. Less parts, easier to manufacture as 3rd idler wheel isn't there. The 3 wheelers are usually 'benchtop' units,semi portable while 2 wheelers are floor mounted beasts. hth jay
Reply to
j.b. miller

There are decent three wheelers around, but not many. If you see something like an Inca close up, it's huge.

One of the advantages of a two-wheel bandsaw is that it takes up very little workshop space relative to its capacity, being neatly arranged in a vertical stack.

-- Do whales have krillfiles ?

Reply to
Andy Dingley

Well, anytime you run something across three items versus two there is more friction, thus more blade wear and fatigue. Make sense?

Jim

Reply to
James D Kountz

If the wheels are the same size and distance apart, and the motor RPM the same, the blade is subject to the exact same bend/straight cycling, so there should be no more fatigue than with only two wheels. In fact, there may be less because the blade is bent for a shorter time each time it bends (120 degrees around instead of 180).

Reply to
DJ Delorie

180 x 2 = 360 120 x 3 = 360 However, it is still flexed 3 times per revolution rather than only two. It is probably the more total flexes rather than the amount it is flexed each time. Perhaps a metallurgist can be more detailed in this. Ed
Reply to
Edwin Pawlowski

No, it's subject to 3/2 as much.

It's bending the blade to fit the wheel, or straightening it afterwards that represents the stress cycling, not just the total bending angle (which is always going to be 360°)

-- Do whales have krillfiles ?

Reply to
Andy Dingley

But with the conditons above one complete blade revolution takes longer because the third wheel in that configuration requires a longer blade,

Reply to
Juergen Hannappel

I have one of the older 16" Delta 28-560. It is a well built, sturdy saw that works great for small projects. It requires thinner (018" -.020") blades as well as a 1/2" max blade width. As a result the saw does not resaw very well. Most sawdust encrusted people need a saw that does both.

I really like having them both. The Delta with a 1/8" blade for quick and sharp corners and my new (very happy with) 16" Jet with a 1" resaw blade.

As compared to the standard 14" two wheeler, the 28-560 is built heavier than current models and I'm sure it, by today's standard, would cost as much or more to manufacture.

If you have room, find one and enjoy.

Dave

Reply to
TeamCasa

At the same RPM, each "revolution" takes 1.5 times as long. The number of flexes *per minute* is the same, for a given linear FPM speed of the blade.

Reply to
DJ Delorie

If it's bending the same number of times each minute, how is that 3/2 the stress then?

Reply to
DJ Delorie

Grizzly makes a small one

Reply to
Ben

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