Monday 21 March 2016

Bandsaw problems - investigations

We mentioned in an earlier post that we had encountered problems with a new Charnwood B350 bandsaw we'd purchased for our company. The inspection door hinge on the saw was rusted and seized up. After an hour's usage the drive belt snapped rendering the machine non functional.

We spoke with the vendor (Charnwood) this morning. They were annoyed on our behalf that we'd suffered problems with the new £600 purchase. Their attitude was "what would you like us to do to fix the problems". Returning the machine is not our preferred option as the faults are relatively minor and moving it up from the basement would entail a lot of work. To help resolve this I said we'd try cleaning the rust from the hinge and applying lubrication to the repaired hinge and then get back to them with the outcome of the work. They have offered to replace the door if necessary. They are also sending a new drive belt to replace the broken one. 

We've already purchased the tools necessary to re-install the drive belt. It is a fairly quick job and one we could expect to have to do periodically during the life of the machine It is a minor inconvenience for us to replace the belt rather than wait for a maintenance engineer or to send the 80 Kg machine back to the shop.

This afternoon we cleaned up the rusted hinge with 400 grit grade emery paper, applied light machine oil and remounted the door on the bandsaw machine. The machine would not start, the metal door had become distorted and wouldn't operate the safety interlock switch. After 30 minutes tinkering  we were able to fix the problem, but we'll be asking for a new door as the distortion arising from the rusted hinge could have long term effects.

While testing the power switching we noticed the machine was running with an odd scraping noise from the area of the drive shaft. We noticed the "key" for the drive shaft was loose and scraping against the back of the main saw pulley wheel when the motor turned. Normally the access door would be closed so you wouldn't be able to see the problem, but we'd overridden the safety switch and had the door open.  We resolved to investigate more carefully and dismantled the lower half of the saw. 

We found that the hidden grub screw at the back of the drive pulley was loose. It had not been tightened during the manufacturing assembly process. Consequently the "key" which locks the pulley wheel to the shaft had not been secured. The pulley wheel was able to freely drift along the drive shaft. It is no surprise the drive belt had become damaged and snapped.

We'll be having further discussions with the vendor tomorrow!! They need to have some serious discussions with the manufacturer. There are some serious issues with quality control.

Edit: Charnwood are sending a replacement door by courier, which is a story in itself.

Edit: 25th March 2016 The faults have now been fixed. While they should not have been present on a new machine, Charnwood has responded in a helpful and professional manner. We'd recommend them. 

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