Table saw blade wobble

[Albatros]

I'm hoping to get some expert advice or maybe just some reassurance about the play I get from my table saw (Sip 12" cast iron table saw). I'll start with a question:

Should I expect to be able to cut slots that are the same width of the keft of the blade I am using? In my case I have a Freud blade with a 2.7mm kerf but it cuts slots that are about 3.05mm wide.

If the answer is yes I should get slots that are the same width then please read on to see what I have tried, in vain, to solve the problem. If you think that 0.35mm is a prefectly acceptable amount of play then don't bother reading the rest! I would like to hear your opinion though.

I get good clean cuts, no kickback and I am confident that the blade is parallel to the t-slots but hearing the blade rattle against my cross cut sled as it slows down is a constant reminder it is not 100% (or is this 'normal'??)
Before I had my current saw, I had the 10" model and I had exactly the same issue with approximately the same amount of wobble (around 3/10 of a mm according to my dial indicator).
I have followed advice from The Wood Whisperer, Mathias Wandel and some other online sources but I can't seem to make any significant difference. Having already trouble-shooted the blade, the arbor and the nut and washer and not really getting anywhere I am questioning if the problem is actually caused by the bed contorting very slightly resulting in the distance between the t-slot and blade constantly changing by tiny fractions as a result of some small vibrations. There is no obvious excessive vibration but I have noticed that pressure applied by one finger to the table top causes the dial, which is resting aginst the arbor, to move by as much as half a mm. This saw has the motor and all the tilt & rising mechanism bolted to the underside of the bed so vibrations transfer directly to the bed.

Any ideas? Am I being too precious about obtaining perfect accuracy or should I expect more from my saw?

 

[Ttrees]

I was chatting to another forum member about this not long ago,and I advised him to check the arbor
flanges and the contact area of them on the blade, as there could have been grit or damage to them.
In the end he chased the problem down to a misalignment of the motor and the Arbor pulley.
I asked him if the arbor bearing had any play in it, and he said he didnt notice any.
Good luck

 

[Trevanion]

I wouldn't worry too much about such a small discrepancy, if it isn't causing any undue vibration or damage it's not going to become a catastrophic problem. Hopefully

 

[Fitzroy]

Have you measured the run out of the blade when the saw is stationary?

I do this with a magnetic dial gauge, firstly in the same spot and turning the blade by hand, and secondly on the same saw tooth from front to back with the gauge sliding in the mitre slot.

If you don’t see any runout / miss alignment with the saw stationary then one would argue that the issue is being introduced trough a dynamic effect, vibration etc.

My problem with the saw blade vibration/run out has always been the lack of consistency in the cut, poor finish and back edges being out of square. If the only problem you have is a slightly wide cut then I’d expect that would be perfectly manageable.

Fitz.

 

[Deadeye]

Well, I'm a rookie...but I have the 10" SIP and so I thought I'd chuck in my tuppence!

Firstly, I think it's very unlikely to be flex in the tabletop. At the point the blade passes through the wood to make the cut the table would need to be really quite bent to change the kerf size by 10%.
As the motor is bolted to the table securely (you've checked of course) and there's no play in the arbor (also checked) and the T-slots are true to each other (checked) and the blade (checked) then I think the issue has to lie in the blade.
Have you put a dial indicator and tested diatance of each individual tooth? Also have you tried a different blade (2.7mm seems quite thin for a 12") and found the same thing. If you make a cut only as far as level with the arbor, stop the saw and pull back, do you still get the rattle? Do you get the same effect using a mitre rather than a sled?
I had an issue with burning that turned out to be the motor poorly positioned (and adjusting it was a royal pain the the posterior), but on the way I found that my blade (also freud) has some (acceptably small) variation in tooth alignment

 

[Albatros]

Have you measured the run out of the blade when the saw is stationary?

I do this with a magnetic dial gauge, firstly in the same spot and turning the blade by hand, and secondly on the same saw tooth from front to back with the gauge sliding in the mitre slot.

If you don’t see any runout / miss alignment with the saw stationary then one would argue that the issue is being introduced trough a dynamic effect, vibration etc.

My problem with the saw blade vibration/run out has always been the lack of consistency in the cut, poor finish and back edges being out of square. If the only problem you have is a slightly wide cut then I’d expect that would be perfectly manageable.

Fitz.

Yes I have tested this with 3 different blades and measuring against the same tooth there is no misalignment. However, misalignment does occur if I compare different teeth. This is why I suspected a bent arbour or possible vibration or something else I haven't thought of. Thanks for the reply Fitzroy.

 

[Albatros]

Well, I'm a rookie...but I have the 10" SIP and so I thought I'd chuck in my tuppence!

Firstly, I think it's very unlikely to be flex in the tabletop. At the point the blade passes through the wood to make the cut the table would need to be really quite bent to change the kerf size by 10%.
As the motor is bolted to the table securely (you've checked of course) and there's no play in the arbor (also checked) and the T-slots are true to each other (checked) and the blade (checked) then I think the issue has to lie in the blade.
Have you put a dial indicator and tested diatance of each individual tooth? Also have you tried a different blade (2.7mm seems quite thin for a 12") and found the same thing. If you make a cut only as far as level with the arbor, stop the saw and pull back, do you still get the rattle? Do you get the same effect using a mitre rather than a sled?
I had an issue with burning that turned out to be the motor poorly positioned (and adjusting it was a royal pain the the posterior), but on the way I found that my blade (also freud) has some (acceptably small) variation in tooth alignment

There is no play in the arbor or bearings, but that isn't to say the arbor isn't a little wonky. It is a strange coincidence though that I have had the exact same problem with both Sip saws I have owned. This has led to much head-scratching and me assuming I am probably at fault. I get the rattle when I turn off the motor and there is anything close to the blade.

I agree that adjustments are painstaking and fiddly on these saws - but it is worth it when you nail it. Trouble is I haven't nailed it and I don't know if it is me or the saw! Thanks for your advice Deadeye.

 

[deema]

Just a thought, not all blades are the sam quality. A lot of blades arnt flat, and what you are describing with the tooth to tooth misalignment is characteristic of a blade that isn’t flat.
So, Mark the blade into quarters and number, check the tooth alignment at each and record the results. Now move the blade on the arbour say 1/4 turn and repeat the checks. If the numbers are the same it’s the blade that’s bent, if they are the same but 1/4 turn out it’s the spindle that’s bent. If it’s random there are two possibilities, it’s either the flanges arnt flat and perpendicular to the bore, or both the blade and the spindle are slightly out. To check which mark the removable flange, and only move this a quarter turn.

I’d place my money of the blade distorting when it’s spun up. However if you’ve got a high quality blade such as a Swedex, OMAS, Orange Chrome etc, it’s likely to be your saw bits.

 

[powertools]

You have several answers but the truth is nobody can help you without more information.
Are you cutting groves with the grain or across the grain?

 

[Albatros]

You have several answers but the truth is nobody can help you without more information.
Are you cutting groves with the grain or across the grain?

The results are the same when cutting either with or across the grain. Maybe I should be gratfeul they are consistent at least!

 

[Albatros]

Just a thought, not all blades are the sam quality. A lot of blades arnt flat, and what you are describing with the tooth to tooth misalignment is characteristic of a blade that isn’t flat.
So, Mark the blade into quarters and number, check the tooth alignment at each and record the results. Now move the blade on the arbour say 1/4 turn and repeat the checks. If the numbers are the same it’s the blade that’s bent, if they are the same but 1/4 turn out it’s the spindle that’s bent. If it’s random there are two possibilities, it’s either the flanges arnt flat and perpendicular to the bore, or both the blade and the spindle are slightly out. To check which mark the removable flange, and only move this a quarter turn.

I’d place my money of the blade distorting when it’s spun up. However if you’ve got a high quality blade such as a Swedex, OMAS, Orange Chrome etc, it’s likely to be your saw bits.

I don't quite follow what it is you are describing but I did what I think might be a similar thing directly on the arbor and I thought I detected a high spot using a dial indicator. I attempted to grind it flat, which I thought I had succeeded in doing, but after replacing the blade and checking the alignment the problem hadn't gone away. I use the red Freud blades which are, I thought, decent blades but not the best.

I think I might have reached the limit of my own abilities to resolve this issue. I think I need to either accept the wobble... or get a new saw!

Thanks for your help Deema

 

[Albatros]

I was chatting to another forum member about this not long ago,and I advised him to check the arbor
flanges and the contact area of them on the blade, as there could have been grit or damage to them.
In the end he chased the problem down to a misalignment of the motor and the Arbor pulley.
I asked him if the arbor bearing had any play in it, and he said he didnt notice any.
Good luck

You might have something here Ttrees - after I bought it (used) I had noticed that the belt was not straight which meant the motor and arbor pulleys must not be aligned, but when I attempted to align them, the motor pulley came into contact with the dust collection unit below/around the blade preventing the pulleys from being aligned. I thought it was odd but assumed that it's a flaw of the design. I will try again and see if I can algn them (which is a pain on this saw - it is a challenge to adjust just about anything).

 

[Albatros]

An update for anyone who might be interested - after making lots of checks and re-checks I came to the conclusion that the wobble is most likely caused by the pulley flange not being true. I tried grinding it using the same technique used by Mathias Wandel in his youtube video:
https://www.youtube.com/watch?v=PXFRsmB0_Ec
I think I may have reduced the wobble by about 1/100 of a mm but no more. In my case I needed to grind the full face of the pulley (about 50mm from edge to arbor shaft), whereas in his video the surface that comes into contact with the blade is relatively small (about 10mm), which made make his approach less suitable for my saw. One thing was very clear though, as soon as the grinding stone was against the flange with the motor running the flange tapped the stone rapidly.
At this point I think I either put up with it or replace the pulley.
Thank you to everyone who chipped in, all the comments were helpful.

 

[Ttrees]

Sounds like your arbor flanges are not true, but have you checked the other ends of the flanges and nut for burrs?
If so...
I needed to lap the flanges on my saw, but it was only a lick was needed, about 20 seconds work.
A good start would be comparing both flanges together to double the error and see if you can see any rotating by hand.

On a lot of saws these flanges are only meant to be in contact with the blade on the outside perimeter,
as when the arbor nut is tightened it flattens out somewhat to grab the blade that much better.
If you have a big hump (in relative terms) somewhere in the middle of the flanges, you will not be able to lap it out if you use a lapping surface larger or the same size than the circumference of them , as it will result in creating a convex surface.

To counter this, you need an abrasive that has a smaller surface area than the flange, and you never run the edge onto the lap.
Not until you have successfully got rid of the hump.
I find a self adhesive sandpaper, or spray gluing some good stuff onto a dead flat surface will hold onto a cheaper abrasive paper
well, and the edges won't curl up because it is 100% supported by the item in question being lapped.
Another benefit is the abrasive lasts longer as it floats off the loose grit which dulls the rest, and ensures better contact area.
You will need to be very methodical with your approach, count strokes and rotate.
Inspect regularly, a marker might be handy... but don't think for a minute that once the marker is removed that the thing is flat!
I see lots of folks thinking that's all there is to it #-o
Good luck
Tom

 

[Albatros]

Sounds like your arbor flanges are not true, but have you checked the other ends of the flanges and nut for burrs?
If so...
I needed to lap the flanges on my saw, but it was only a lick was needed, about 20 seconds work.
A good start would be comparing both flanges together to double the error and see if you can see any rotating by hand.

On a lot of saws these flanges are only meant to be in contact with the blade on the outside perimeter,
as when the arbor nut is tightened it flattens out somewhat to grab the blade that much better.
If you have a big hump (in relative terms) somewhere in the middle of the flanges, you will not be able to lap it out if you use a lapping surface larger or the same size than the circumference of them , as it will result in creating a convex surface.

To counter this, you need an abrasive that has a smaller surface area than the flange, and you never run the edge onto the lap.
Not until you have successfully got rid of the hump.
I find a self adhesive sandpaper, or spray gluing some good stuff onto a dead flat surface will hold onto a cheaper abrasive paper
well, and the edges won't curl up because it is 100% supported by the item in question being lapped.
Another benefit is the abrasive lasts longer as it floats off the loose grit which dulls the rest, and ensures better contact area.
You will need to be very methodical with your approach, count strokes and rotate.
Inspect regularly, a marker might be handy... but don't think for a minute that once the marker is removed that the thing is flat!
I see lots of folks thinking that's all there is to it #-o
Good luck
Tom

I have checked the nut and washer/flange for burrs and I have placed the flange on a flat surfare to check for any wobble but the nut and washer/flange seem fine. The flange/washer is in contact with the blade on only the outer perimeter (approx 10mm wide). However, on my saw the blade rests against the full face of the pulley (minus the arbour shaft) which is approx 50mm radius from the edge of the arbor shaft to the edge of the flange, so any lapping/ grinding needds to be done over quite a large surface area.

I've now tried three times to grind the bump out and I have maybe reduced the wobble run-out to 0.2mm. I would love to resolve this problem myself but I am a novice and I don't think I have the skill required to reduce it any further. I might just buy a replacment pulley and arbor shaft (I'm not certain the problem is not with the arbor shaft being out of true) which would cost me about £30 and might at least help me decide if the problem is me or my saw, although if the problem is unchanged I'll be none the wiser :?

Thanks for you words Tom. This forum is great but I can't be sure I am applying the excellent advice I get correctly. What I really need is a mentor, someone local who can be coaxed into visiting my workshop and solving all my problems for me!

 

[powertools]

Just because your machine will take a 12" blade does not mean you have to use a 12" blade.
From what you say you are using a 12" blade with a small kerf to do shallow cuts and I think that is your main problem, that blade is very thin and is likley to vibrate doing shallow cuts.
A 12" saw is great for doing cuts through thick material but not so good trying to do accurate cuts in thinner material with a thin blade .
My advice would be to use a smaller dia blade when working with thin material ,then even if the others are right and there is a major problem with the saw a smaller dia blade will greatly reduce the problem.