Ed's Editorial

Grinders and TYPES of belt tension… Some Interesting insights.

For a long time I have watched as more and more 2 x 72″ grinders on the market utilize Gas Spring Cylinders (https://www.mcmaster.com/#spring-cylinders/=1byb3fm) for belt tension.  I’ve tried it too, and in the beginning, had durability issue….the cylinder rod seal would fail within weeks or days of me putting one of the grinder.  I finally figured out that I could make them last by using a “boot” zip tied on, to protect the rod/seal from all the grinder debris floating around.   But that’s a different story… the whole reason for this post is to expose something that I find very interesting.  These cylinders are NOT the “end all” that many make them out to be….particularly when it comes to belt grinder tensioning.    I have/use/like the KMG grinders.  I have changed mine to direct drive, and love it’s rock solid/heavy build quality.  I tried using one of the Gas Spring Cylinders on it, and found that when used on this particular grinder, Gas Springs seem to cause more issues than they solve.  A few grinding session after installing the Gas Spring Cylinder on the KMG, I notice that I was getting serious belt chatter on both 50 and 120 grit belts.  I tried adjusting the mounting locations and positions of the Gas Spring Cylinder, but nothing helped.  When using a flat/glass face platen, the belt chatter was so bad it made grinding nearly impossible….no matter what brand, backing, or type grit of 50 or 120 grit belt I used.

I spent a small fortune on different poundage rated Gas Spring Cylinders from 20lb, all the way to 90lb, all with the same, or additional issues. depending on the poundage rating…….

Out of frustration, I removed the Gas Spring Cylinder, and reinstall the coil spring mount, and the coil spring….. NO MORE BELT CHATTER!!!   I pondered this for a while, and can only come up with the following……  A Gas Spring Cylinder is built to apply a specific poundage of force.  I believe that the pressure applied to the belt when grinding caused addition tension on the belt before it reached the drive wheel…..and a slight amount of slack after the drive wheel.  The constant tension of the Gas Spring Cylinder is what caused this.   On the other side of the coin, a typical coil spring provides for a “variable” amount of tension, based on the amount of “drag” I cause when applying pressure during grinding.   Preventing the situation, or part of the belt having more tension than the other, and in turn, eliminating the belt chatter!  Since returning to the simple coil spring for belt tension, the infuriating belt chatter has been eliminated!

OK, What’s the take away?   1st….. just because something is “cool” doesn’t mean it works well.  2nd….. the latest and greatest, just might not be.  And finally……if you’re having issues with belt chatter on a grinder…… it MIGHT just be the TYPE of tension mechanism!  🙂