Sometimes an upgrade makes things worse

I have a machineMart/Clarke 7"x12" bandsaw in the shed. I bought it second hand via fleabay as an upgrade to the 4"x6" that I'd bought new. It has done good service since I had it, but had/has a few issues. Earlier on this week, while tracking down a problem with the NVR switch (checked the two 'safety cut out' microswitches and eventually found a spade connector on the switch itself, that had a bad contact, overheated and relaxed the female half of the connection. Pliers sorted this|) I decided that I should get around to changing the worn out belt for the replacement that I bought a couple of years ago. First thing was to align the motor and saw pulleys, which were about 1/8" out of line with each other. Then I fitted the 'new' AX650 belt to replace the badgered A650 belt. The reason for getting an AX (cogged) belt was that the pulleys are too small for an A sized belt and the cogged belt would last better...

Today I was cutting up a number of pieces from 6mm x 200mm steel plate to make the bits of a box that will be welded together. When the bandsaw blade got to about half the width of the material, the saw started chattering horribly. I've cut 12"/300mm steel with this saw before and not encountered this.

A scan of the Interwebs indicated loose blade or loose belt. I tightened the blade as much as I could (not much, it was already set properly). No difference. The belt was running hot, so I tightened the belt to a worryingly high amount (bearing load). No difference.

Eventually, I tried putting the old, wrapped, belt back instead of the new 'improved' cogged belt. Problem went away, even with lower belt tension.

The cogged belt should have been stronger than the wrapped belt and slipped less. I can only guess that the wrapped belt was better at damping vibration.

Got to order a new A650 belt now

Edited By Mark Rand on 22/09/2023 23:05:23

Never fix a working machine…

Dave

Several years ago I decided to fit a pair of better V belts to my Warco VMC milling machine, so I bought a pair of new cogged belts,

The result was horrific, with knocking, clanking and rattling as the hinged intermediate pulley and the motor on it's hinged mounting plate vibrated and jumped about. Examining the two new cogged belts revealed that the shape of the V section was not consistent along the length of the belts, causing the belts to ride in and out of the V pulleys affecting the belt tension.

I replaced them with a pair of ordinary V belts and peace was restored.

 So yes, what Dave S said!

Edited By Lathejack on 23/09/2023 20:35:35

Edited By Lathejack on 23/09/2023 20:37:20

Agree to both.

I got the new belt some time ago because there was a fibre obviously sticking out from the original. Easily seen on this saw, since the original owner had dropped something heavy on the saw and ended up cutting the end off the belt guard, presumably because it was buggered. One of the plastic wheels was knackered as well, so it's now got 3 plastic wheels and one solid aluminium one.

I thought that the AX belt would be better because of the small size of the step pulleys' smallest sheaves. Ah well, live and learn. I might even get around to bending up a new end for the belt guard and TIGing it on one of these years...