Makita LS1013 compound mitre saw - blade issue

I've a nice Makita chop saw which has been really good over the years.

Just recently the blade centre bolt has started loosening off which is far from ideal. Obviously a LH bolt tightened up really well but it will still unwind after a few cuts. I could see that may just occur if the blade came to a dead stop after a cut, but it doesn't.

Tends only to do small cuts and softish timber. No prolonged stressing as would be in an Oak beam.

Any thoughts on the cause or a good fix? PTFE threads?

that shouldn't happen EVER......

make sure the blade and backing washers are clean and free from dust n stuff.......

I'm 72 and in all my years I have never had one of those bolts come loose......

I've had em when I needed an air gun to get em off tho.....

if all is well u can use a little thread lock compound, more like screw lock.....it's a weak grade.....

but really should not be nec.....

I wonder whether a heavier bolt would help so that you get more self-tightening on start-up.

"Any thoughts on the cause or a good fix? PTFE threads?"

Certainly not PTFE as that is a lubricant.

Bob

Maybe have a sacrificial oak beam to tighten it up?

I've had it maybe 8+ years with no issues.

Typically used it this morning for about 30 minutes without problem.

All very strange!

Vibration is an excellent way of loosening bolts. What is the 'softish timber'? Possibly it's a mix of hard and soft fibres that vibrate the bolt, whilst 'small cuts' don't put enough force on the LH bolt to re-tighten it.

Are you thinking Nylock rather than PTFE? I'd try thread-locker, or even super-glue.

Dave

Edited By SillyOldDuffer on 06/12/2021 12:49:49

This sounds, Jon, like a situation where Nord-Lock washers may help.

Just be cautious about buying them from Zoro.

EtA: I'm not sure they work on left-hand threads, though. Theoretically they shouldn't, but Nord-Lock doesn't seem to even mention the matter.

EtA 2: A bare "The standard assortment is for right-hand thread" is the only reference I've seen in Nord-Lock's promotional material.

Edited By Bill Phinn on 06/12/2021 13:31:47

I've not had one come loose though I did have the head shear off an Electra Beckum chop saw once, luckily as the blade was down so it just rattled to a stop..

As said by clogs make sure its all clean and a low strength thread locker. Also make sure bolt is tightening if you have changed to a thin kerf blade at some time.

In 25 years of working with(as a plant mechanic) chop saws of various makes the only times they have come loose is either operator error by not pinching them up enough(Not hanging on a 6ft pole), not cleaning the mating surfaces when replacing the blade and finally fitting a replacement blade that is made of thinner material to the original in which case can be overcome with two paper washers.

The biggest problem is those that are so tight they have been tightened by the local gorilla on site

Edited By Derek Lane on 06/12/2021 13:56:45

Strangely the force from cutting should tighten the nut.

P.S. What is wrong with the poxy spell checker?

Tony

I would suspect that you are suffering a vibration problem, that could easily be the cause; has the saw started vibrating more than usual and is there evidence of any problems, e.g. bearings worn which could be a source of vibration. Dave W

.

Adding to that ^^^

I would suggest checking the condition of the saw-teeth … a blunt or chipped tooth can be enough to induce excessive blade vibration.

MichaelG.

Have you by any chance replaced the blade recently? I only ask because my plunge saw started doing the same thing after I fitted a new blade - discovered the new blade was a smidge thinner than the old one, thus not tightening fully.

G.

Are you using a reducng bush in the blade that is thicker than the blade.

A thinner blade may need to have the recess the clamping washer to be machined a little deeper.

Replace the clamp bolt with a brand new one plus flat washer and star washer.

Clean the clamping and blade oil and grease. Silcone lubricant spray if used on the saw is often the cause of the blade clamp slipping loose.