Bearing & Squaring

 

What are the major factors you should look for when buying a panel saw.

There are two kinds of panel saws, vertical and horizontal. Each of them have pros and cons.  The biggest difference is the space needed to work with these machines. The vertical saw takes up much less floor space, and is easier to load one sheet at a time.

Without getting into the weeds any further about the types of panel saws, we will discuss the vertical saws for the remainder of this article since they are the most familiar/common and most likely used by small shops and Home Center stores.

A panel saw is just a big guide for a circular saw so it can cut sheet goods at 90 degrees (Cross Cut)  or parallel ( Rip Cut).  There are 2 key elements to doing this;

The first is the tracking mechanism for the saw to move up and down for cross cuts;

The second is the alignment system for the supported material to be cut vertically and horizontally.

By tracking mechanism, we mean what allows the saw to move up and down the guide tubes for the vertical cross cuts.  If there is “play” in this mechanism, the cut will not follow a straight line.

There are two types of bearings used in most panel saws.  The first is a low cost U-bolt with nylon rings around the U.  The rings are squeezed between the guide tubes and the U bolt at the same time.  As these rings try to roll, the carriage moves on the guide tubes. A bottom button glide is used to “Load” (put pressure) on the U-bolt rings.  As you might already see the flaw in this system is friction.  The tighter you get the tolerances to take out the play, the harder it will be to move the carriage causing a trade off of ease of movement and accuracy of the cut.

The Second Bearing system is using a “true bearing” using real sealed bearings.  This is done by high end vertical panel saws typically costing over $25,000 but there is one company making panel saws for a tenth of that figure using actual bearings.  This company, (Saw Trax Mfg. Inc.) makes their panel saws in Kennesaw GA.  They use 3 sealed bearings per carriage corner for a total of 12 sealed bearings per carriage.  This arrangement has two bearings on top to carry the weight and one bearing on the bottom to “Load” the top bearings.  The bottom bearing ensures constant pressure during a cross cut.   By using a true sealed bearing system like this, you get both accuracy and ease of movement during a cut.

The alignment system consists of two elements.  The first is ensuring the guide tubes stay square to the material rollers.  The second is to make sure the material rollers stay aligned with each other.

Different panel saw manufacturers handle this in different ways.  One manufacturer has the outside rollers on hubs that have a centered hole and all the interior rollers on hubs that have off-centered holes.  This off-center allows the interior rollers to be adjusted up or down to align with the outside rollers.  The problem is there are no 10 ft. straight edges that allow the end user to re-adjust the rollers once they go out of alignment.

This same manufacturer has users hit the guide posts with a dead blow mallet to adjust the tubes right or left when the vertical tracking goes out of alignment.  Obviously, this can take a lot of whacking back and forth to get it right.  A secondary issue is if you whack too hard, you can dent a guide tube and render your machine useless.  Our issue with this system is there are 13 adjustments that can throw your machine out of square, the 12 interior rollers and the guide posts shifting.

An innovative approach to the alignment system elements is to not have an indexed adjustment to the rollers and guide tubes.  If all the rollers and hubs are the same, they don’t go out of alignment.  If an adjustment is needed to align the fences, an indexing system is used to incrementally adjust the end of the fence up or down in 1/32″ increments and then locks into place.

A similar indexing system is used for the vertical guide tube posts is patented.  The manufacturer calls it the “Accu-Square“.  Nine holes spaced 8/32 apart are centered in the frame.  Another nine holes spaced 9/32 apart are centered in the bottom guide tube bracket.  Only one hole in the frame and guide tube bracket will line up at any given time and adjustments left or right can be made in 1/32 increments.  Once adjusted, the bracket is locked to the frame using a sheet metal screw keeping the guide tubes from ever shifting in relationship to the frame.  This system is patented and is guaranteed to never go out of square.

When you combine the dependable Makita saw with the sealed bearing and Accu-Square squaring advantages of the Saw Trax Panel Saws, the decision of which panel saw to buy becomes an easy one.

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