Link belts for the Unisaur

[Steve Turner]

Not that it really needs them, but I've been wanting to give my Unisaw a birthday present of replacement link belts for quite a while, and since link belts are sold by the foot, I need to figure out how many feet to buy. I just measured the outer circumference of one of the original belts with a piece of string and came up with the distance of about 25-1/2" inches. "Well *that's* dumb" I says; if it were 24" I could buy six feet instead of seven (there are three belts), but then I thought that perhaps belt lengths are measured along the inner circumference rather than the outer, and six feet of belt *would* be enough. 'Zat true? Can anybody clarify how many feet of link belt I *really* need to buy?

[dpb]

Yeah, easily...0"

Buy the matched set; a) I don't think they can reproduce link belts sufficiently accurately to work well as matched sets and b) they're a (moderately expensive) solution looking for a problem.

But what's one extra foot anyway, and you may need the extra link or two to be able to get them installed if you're adamant of going ahead.

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[Russ Stanton]

Multiple belts are used due to transmission of sufficient power without belt slippage. The belts need to be a "matched set". If the lenghts are off by just a bit thenthe shortest belt is transmitting most all of the power and when you looad the saw down it will start to slip.

[Swingman]

Yep ... ZERO. One of the reasons you have a Unisaw is that it doesn't need link belts. :)

Really, not recommended at all.

[dpb]

Swingman wrote: ...

Dang, is that an echo??? :)

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[Swingman]

LOL ... guess it was. Sorry, didn't see your post until you mentioned it and I went back and looked.

Fighting Thunderbird 3.0 here ... double posting, missing posts buried in jungle layers of threaded and unthreaded, read and unread, and phantoms that don't show up at all.

Chalk it up to great minds ... :)

[Max]

And, after all, it's nice to know when two people agree on *something*.

Max

[Markem]

I replace a very old set of matched belts, with link belts and have experienced no problems for the 3 years. Counting out the number of links so all three matched length. The manfacturing process of the links seems to create a real uniform product link to link.

As far as the Steve's question I bought 7 feet and had about a foot left over.

Mark

[Steve Turner]

Ok, then perhaps I just need to replace the belts I have. Right from the beginning (almost 10 years ago, I guess) they seemed to have a "memory" that made them want to assume an oblong shape, and I remember going through every phase of tensioning from super tight to super loose trying to remove the startup THUMP that would occur when the belts got out of sync with each other (their memory "humps" were all in different places). I don't remember the manual giving me a clear recommendation on how tight the belts should be, but I've been running them pretty lose for many years now, which (as I recall) pretty much gets rid of the thump but of course there is some belt slippage when the motor starts up, and I don't think the saw is running as smoothly as it should because the belts are flopping around. Suggestions?

[Swingman]

a 1/4 of the way down the page.

[Leon]

To help guard against memory buy a higher quality automotive matched belt set, preferabley the one with notches so that they will bend into a tigher radius. Typically wood working equipment comes with the cheaper industrial type belts.

[Larry Jaques]

On Sat, 09 Jan 2010 13:54:17 -0600, the infamous Steve Turner scrawled the following:

Walk out to your shop, cut your old belt off the saw with pruning shears, and measure the length. Now go buy that manys. ;)

Both packs I bought were 6'. I still have one.

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[dpb]

Swingman wrote: ...

...

I've not updated from 2.xomething; maybe I'll wait... :)

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[dpb]

Steve Turner wrote: ...

The ideal tension for a V-belt drive is the lowest tension at which the belt will not slip at the highest load condition. (Gates Rubber)

General guidelines....

1. For installation, reduce the center distance so the belts may be placed in the sheave grooves without force. Arrange the belts so that both the top and bottom spans have about the same amount of sag. Apply tension to the belts by increasing the center distance until the belts are snug and have a live, springy action when struck with the hand.
2. Operate the drive a few minutes to seat the belts in the sheave grooves. Observe the operation of the drive under its highest load condition (usually starting). A slight bowing of the slack side of the drive indicates adequate tension. If the slack side remains taut during the peak load, the drive is too tight.
3. Check the tension on a new drive several times during the first 24 hours of operation, by observing the slack side span.
4. If a V-belt slips, it is too loose. Increase the tension by increasing the center distance. Never apply belt dressing, as this will damage the belt and cause early failure.

There are rule-of-thumb formulae to give ideas of the tension for a given horsepower and geometry; I'll not bother w/ them here as I'd surely think Delta will have guidelines. If you don't have the data surely somebody else w/ a Unisaw will. I've a PM-66 not Unisaw but if needed I can look up their recommendations; I don't recall offhand.

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[Martin H. Eastburn]

Granted, but as the belt(s) begin to wear in, you start taking out links to make up for the compression into the V's of the pulleys. One can measure the pressure it takes to compress the long lengths to a certain point or the stiffness of the belts - what deflection from zero... I suspect matched belts start out good, but they get dirty in different amounts and thus don't match long after installation.

Mart> Multiple belts are used due to transmission of sufficient power without

[Lew Hodgett]

You can't get there from here.

You require a 3 belt matched set.

Link belts don't do that.

Lew

["<<<]

Just a FWIW .. .. .. a few years ago, my Woodmaster 718 developed a vibration. It is a 2 "matched" belt system. Just to check it out, I pieced together some link belt pieces, and installed it in place of the

2 originals. The vibration disappeared, and I never have either replaced the "matched" set or added a second link belt. It has been running just fine on one link belt ever since.

Now, if you think you can ever load up the arbor on your saw to exceed that of an 18" planer,perhaps it is correct of you to go buy a matched set and be done with it. Myself, I'd try one or two, or even 3 link belts without hesitation. Look at it this way .. IF you were to install 3 link belts .. would this not be a likely scenario. The shortest belt will begin to take the load .. .. IF the load gets great enough to stretch the first belt, the second one begins to grab. IF they both can't pull the load (RIGHT !!), #3 kicks in, and what, exactly have you lost ??

All the theory and logic in the world don't mean squat when you just try something and it works .. WITHOUT any negative side effects. What would be the worst case scenario for simply trying that which you propose ?? NO HARM .. NO DAMAGE .. NO PROBLEM .. go for it, and let up know how well it works out for you. Be sure to let us know how much it slipped !!

As for your original question .. buy 6' of link belt .. if you get 3 out of it, great .. if not make 2 .. run them as is and get the extra foot of belt to make up #3 if you really think it's necessary.

[Martin H. Eastburn]

Link belts wear in after a few hours of use. They conform to the V's. The exact number of links can be in each belt. As a belt takes more pressure, it wears in more and matches.

These belts were designed for conveyor belting on muli-HP motors and up to 4 belts on a pulley to drive a section of the belt.

They auto-match if anywhere close in the first place.

Mart>> "Steve Turner" wrote:

[Bruce]

On Sun, 10 Jan 2010 18:57:05 -0700, Bøb __ wrote (in article ):

I run 2 link belts on my Unisaur. I have enough for the third but never bothered.