Saw blade bushes...cause problems?

**Redgy** · 11th June 2013, 08:09 PM

Hi all,

Apologies in advance for long post

I recently upgraded my contractor saw to a new cabinet saw and have been having a few issues with existing blades. The problem is a small wobble which leads to rough rips and inaccurate cross cuts.

The blades and their story....all 10 inch

CMT rip blade.....had used this on my contractor saw for about 6 months. Has a 30 to 5/8" bushing. Loved it on the old saw but on the new saw it is terrible, in fact so bad I won't use it even for a rough rip as it is borderline dangerous when it wobbles and catches the board. I initially thought the belts were slipping, which happened on the old single belt contractor saw a couple of times when I pushed it and the blade wobbled. Not the case though here. I have setup all the basics as accurate as I can with dial indicator for blade parallel to mitre slot, fence parallel to mitre slot, fence & blade square to table. Dial indicator on the flat face of the arbor flange moves 0.02mm rotating by hand...that's ok isn't it? Less than a thou?

Makita Blue 60 tooth cross cut.....also used this on the old saw for few months and maybe made 100 cuts with it, nothing over 12mm so hardly had a hard short life. This blade also has a 30mm to 5/8" bushing and also performed flawlessly on the contractor saw. I have used this blade on my new saw and been happy with it, cut the kerf in my new crosscut sled...beautiful, cut the zero clearance cuts on Incra sled...beautiful. And I have made quite a few 90/45 cuts on the new saw....no problems. Until today. I didn't realise early enough why the incra sled was getting shaved as I pushed it through for a few mitres, until I checked the mitres...way off. They are 45 but not straight and visible rough saw marks at the start and end of cut. Anyway I sat the incra sled stationary bit (off cut catcher?) in the right hand mitre slot and turned the saw on, left it running for about 2 minutes and constant noise about every 2-3 seconds where the blade wobbled and took a bit more off the previously zeroed edge....in fact it is now buggered with almost "chunks" out of the edge...about 0.5 - 1.0 mm

The rip blade that came with the saw....no brand, 1/8" kerf, no bushing just 5/8" hole, no frills like vibration slots, just a chunk of steel with teeth. Also no wobble, no problems at all (bit rough on cut edge but that's ok for what it is.)

Freud glue line rip, thin kerf....brand new from USA. All the bells and whistles, beautiful blade, smooth rip cut. No bushing just 5/8" hole. No problems either, no wobble etc.

What else have I done?....made sure the flange and flange washer are spotless before installing each blade. Cleaned the 2 older blades of sap/gum etc. Checked the bushes for fit and in line with the blade plate. I put the slightly used Makita blade on and hand turned with the dial indicator showing +/- 0.05 mm on full rotation. The brand new Freud which has no "wobble" problems is +/- 0.06...actually worse than the Mak blade that has a wobble.

So a couple of questions after all that....

1. Why did the first 2 reasonable quality blades work ok on the old saw but not the new one, and more perplexing

is what has happened to the cross cut that has worked fine until today?

2. The 2 that have the "wobble" problem have bushes....should I just chuck them and buy 5/8" blades only? (limits what I can get off the shelf here in sunny Adelaide). Can bushes cause this problem? Why not on the old saw.

3. Maybe a problem with the saw? But not manifesting with all blades

Again sorry for the longwindedness but this has me a bit lost so I'm hoping some of you clever guys can give me some more idea.

Cheers
Redgy

**NCArcher** · 11th June 2013, 08:25 PM

The bush shouldn't contact the blade flange so it won't affect the cut. It is only there to hold the blade central.
It sounds like the two blades are at fault. Put a thin straight edge across the saw plate, not touching the teeth, and check that they aren't warped.
If they're not flat they can be re-tensioned by a saw doctor I think, if they're worth keeping that is.
Come to think of it, there was a post recently where the insertion of reducing bushes was affecting the saw plate as they were too tight a fit. Not sure if this is the case here as you have been using these blades in the old saw.

**Redgy** · 11th June 2013, 09:08 PM

Originally Posted by NCArcher

The bush shouldn't contact the blade flange so it won't affect the cut. It is only there to hold the blade central.
It sounds like the two blades are at fault. Put a thin straight edge across the saw plate, not touching the teeth, and check that they aren't warped.
If they're not flat they can be re-tensioned by a saw doctor I think, if they're worth keeping that is.
Come to think of it, there was a post recently where the insertion of reducing bushes was affecting the saw plate as they were too tight a fit. Not sure if this is the case here as you have been using these blades in the old saw.

Firstly made me realise how much I miss working in a sawmill with free access to a massive sawshop and quality sawdoctors.

Anyway, just thinking out loud here but the 2 blades that are giving me trouble are both old (not very) and have bushes and they were ok in my old saw. The difference to where they operate now? these were in a right tilt saw with the flange nut & washer doing up on the left side of the blade, now in left tilt with the washer doing up on the right side of the blade. Also the flange/washer was smaller on the old saw. Could they have any sort of memory effect? I don't think so because it's just a steel plate squashed between 2 flat washers essentially but as stated I'm just thinking out loud which is possibly a bad idea on a public forum

I'm inclined to give these blades to the new owner of my old saw and buy a couple more new non-bushed blades.

Redgy

**Mr Brush** · 11th June 2013, 09:11 PM

Maybe use the "good" blade supplied with the saw to check for arbor runout using a dial gauge?

My JET saw also has the 5/8" arbor, and to be honest I'd never use a blade that required a reducer. There is plenty of choice in quality blades manufactured to fit a 5/8" arbor - most of the really big names are available to fit your saw.

The other thing you could try is a blade stabiliser, such as

Saw Blade Stabilizer Sets

but you should really only need these for narrow kerf blades.

**Mr Brush** · 11th June 2013, 09:14 PM

If you are going to buy a couple of blades with 5/8" arbor, take a look at the Infinity range. Buy direct from their US website - prices are very good, and if you include a couple in one shipment the freight is reasonable.

Their combination blades are particularly good (for ripping and crosscutting), plus maybe a dedicated ripping blade as well?

**3 toed sloth** · 13th June 2013, 10:45 PM

Hey Redgy I had a mysterious problem with my new TS also regarding blade wobbles but if anything yours is even more mysterious :confused:
In the end I have stopped trying to work out why they wobble. I've satisfied myself that the ts is spot on and it sounds like yours is too. So if the blade wobbles for whatever reason get rid of it as you said.
There seem to be plenty of 5/8 blades in 250mm but for300mm blades they're all 30mm holes. The only 300mm blade Ive found with a 5/8 hole is CMT. Personally I'm avoiding bushes from now on.

Sent from my GT-I9100 using Tapatalk 2

**Redgy** · 13th June 2013, 11:09 PM

Originally Posted by 3 toed sloth

Hey Redgy I had a mysterious problem with my new TS also regarding blade wobbles but if anything yours is even more mysterious :confused:
In the end I have stopped trying to work out why they wobble. I've satisfied myself that the ts is spot on and it sounds like yours is too. So if the blade wobbles for whatever reason get rid of it as you said.
There seem to be plenty of 5/8 blades in 250mm but for300mm blades they're all 30mm holes. The only 300mm blade Ive found with a 5/8 hole is CMT. Personally I'm avoiding bushes from now on.

Sent from my GT-I9100 using Tapatalk 2

Yep I've given up trying to figure it out, spent way too much precious shed time mucking around with this and frustrating the hell out of myself. New Freud blades on the way via Amazon....5/8" hole, no bushes. I have 1 freud (30 tooth glue line rip, thin kerf) which is a great blade and fine in the new saw.... so I've ordered a 24 tooth flat top grind rip and a 80 tooth cross cut blade. Still got the no brand 40 tooth blade that came with the saw as well.

I rang/visited every tool shop in Adelaide yesterday that I could think of and all I could find was 30mm arbor in 10", even Carbatec's CMT range...all 30mm. I guess it's cheaper to manufacture all one size and offer bushes. Anyway hoping it is as simple as the blades

Thanks all for the replies
Redgy

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