Thread: Blade cut is wider than blade kerf

I have the same saw but cant say I have ever measured my kerf. As long as it's cutting square Im not sure it's worth worrying about.

Only thing I can think that may introduce some run out is if the blade nut is on the wrong way or the saw is faulty/damaged. I'll openly admit the first few weeks of having my saw I foolishly had the nut on backwards. Lucky nothing went wrong but when I first tried installing a new blade I didnt realise the circular half of the nut went in towards the blade and rests within the large washer. The manual wasnt clear and I figured the washer with the nut pressing against it was holding the blade firmly in place.

Could be a bunch of things, Could be technique, could be fence flex, could be vibrating blade, could be one of your tooth is bent ever so slightly. Hard to say without ruling them out one by one.

I almost never weigh in on power tools, but I had a TS here in the states at one point (delta hybrid) that had runout almost identical to what you're saying. In my case, it was .01" at the very end of the tooth, and it did create problems when trying to cut stock square.

I hardly use power tools for much so it's long gone.

If you want to see what's most likely responsible, if you have a second blade, perform the same test. Even if it's a smaller blade, you can adjust proportionally.

I'm responding only because you mentioned a crosscut sled and the real pain of mine was that if you were ripping or crosscutting stock and you set the blade square accurately with a square, you'd cut the stock and then find out it didn't match the square. On thicker stock, it was glaring.

With the wobble, it did have a tendency to cut without burning things a lot easier, though.

I’ll do some more tests to see. I’ll make a video so you can see what I mean. As I said, I’m don’t think it is affecting my cuts thus far. But I haven’t had the saw for very long and haven’t done any really detailed work with it yet. I also wonder about how this would impact dado cuts.

Assuming it is an issue with the saw, is there such thing as acceptable runout for a tablesaw of this quality/price range? Or should it be bang on zero?

Originally Posted by tonzeyd

Could be a bunch of things, Could be technique, could be fence flex, could be vibrating blade, could be one of your tooth is bent ever so slightly. Hard to say without ruling them out one by one.

Have you checked that the saw arbor / blade is correctly aligned to the table mitre slots??

I'll add to the list,

• arbor bearings wear / alignment,
• debris caught up between the arbor flange, saw plate & washer / nut;
• how the saw blades are stored (V or H) and handled (stuff stacked on top of them etc);
• sharpening (new or resharpened)
• has the saw blade/s been stressed (overheated during ripping etc)

If you look to the saw milling industry, large circular saw blades are/were routinely inspected and sent to the saw doctor for remediation if found to have unacceptable runout. It is truly an experience to watch a skilled saw doctor work their magic hammering a saw plate back into true - a near lost art. Not viable for small blades though.

If you rule out the listed items, then it starts to look like a saw arbor alignment issue.

Originally Posted by lemerv

I then setup my digital alignment gauge and rotated the blade a full revolution and the alignment gauge deviated about .25mm from the zero point.

Cheers

0.25mm is about 10 thou and I've read that under 4 thou is an acceptable tolerance. Sawstop say that 10 thou is acceptable but like you that was the deviation I was getting and as a result, wider kerf. So the blade is acting like a wobble blade. So I aligned the blade to be under 3 thou (0.07mm) with the slots and made sure the fence was parallel with the slots. So the fence, slots and blade need to be parallel. Saw kerf now is only slightly wider than the blade through natural vibration. I don't think they could ever be the same.
Anyway I think you should realign your blade with the slots. I am assuming your blade is flat and the arbor of your saw is running true.

Just to clarify.

I put the digital alignment gauge in the mitre slot. Zero it against the face of the blade. Then I don’t move it.

I then slowly rotate the blade and watch the alignment readout. This is what deviates 0.25mm. So basically I can zero the gauge, and then rotate the blade through 360 deg. It will slowly move out to 0.25mm and then back to zero once I reach the starting tooth.

So as far as I understand that is nothing to do with the blade alignment to the mitre slot. It seems to me this can only be either the blade is not flat or the arbor is not aligned. But since I tried it on a different blade and got the same result, I’m thinking it must be the arbor?

Is there another way to test this?

Originally Posted by lemerv

Just to clarify.

I put the digital alignment gauge in the mitre slot. Zero it against the face of the blade. Then I don’t move it.

I then slowly rotate the blade and watch the alignment readout. This is what deviates 0.25mm. So basically I can zero the gauge, and then rotate the blade through 360 deg. It will slowly move out to 0.25mm and then back to zero once I reach the starting tooth.

So as far as I understand that is nothing to do with the blade alignment to the mitre slot. It seems to me this can only be either the blade is not flat or the arbor is not aligned. But since I tried it on a different blade and got the same result, I’m thinking it must be the arbor?

Is there another way to test this?

I would repeat this procedure at two positions in the mitre slot - one at the "front" of the blade, and then again at the "back" of the blade. If your blade is aligned perpendicular to the mitre slot, there should be no need to "zero" your alignment gauge a second time when you move it from one position to the other - the measurement should be the same.

Measuring at one point only does not confirm alignment of the blade perpendicular to the mitre slot - it simply measures the blade "run-out" or side to side movement.

Originally Posted by BMKal

Measuring at one point only does not confirm alignment of the blade perpendicular to the mitre slot - it simply measures the blade "run-out" or side to side movement.

Blade runout is exactly what I am trying to measure. Just to recap - if I raise my saw blade into a bit of wood and cut a few mm into it, it creates a cut that is 3.55mm wide, even though the blade kerf is 3.2mm. When I do my experiment with the alignment gauge I get 0.25mm deviation.

So it seems like my blade runout is between 0.25-0.35mm. I’m wondering if this is acceptable or not?

As I said earlier, it hasn’t been a problem to date but I’m also new to tablesaws so it might be something that becomes a problem down the line as I start doing more detailed/different types of cuts.

If I’ve read this correctly you’re seeing a maximum deviation of 0.25mm? I.e. 0.125mm either side of centre? Well; firstly you need to identify if it’s the blade or the arbor. First take the blade off and ensure every mating surface is clean with no burs or dings or paint or anything at all preventing full surface contact. Then check again. If the deviation is still there then mark the maximum spot on the blade, then take the blade off again and put it back on but with the spot about 90 degrees away. If the deviation is still on the spot then the blade is the problem. If the deviation is in the same spot on the arbor as before then the arbor has an issue. If it is in a completely random spot then it will be either a combination of both errors; or just random sloppiness in the machining of each and every separate component.

Is that really an issue though? Unless you’re in Hammer (or similar) territory a tablesaw is not exactly a precision machine and the cut edge likely requires further work to remove the saw marks before either gluing or finishing. I generally do my rough dimensioning with either a Triton workcentre, a track saw or by hand and shoot to size with a plane.

I make inlay banding which requires considerable attention to accuracy & precision. My TS is a Woodfast TS250 which is a pretty good machine for its price. I spent 3 full days setting up the sliding table (no mitre slots at all) parallel to the blade, coplanar with the cast iron table etc. Talk about an exercise in frustration as the manual's adjustment procedure is BS imho - mostly because it isn't for the same machine construction. It's about as good as I could get given the design of the machine. I reached a point that any further adjustment was not practical, as the adjustment bolts and design make it a bit of a lottery keeping the metal where you want it.

My point as ChieffTiff says - there is a limit with budget machines.

Originally Posted by lemerv

Blade runout is exactly what I am trying to measure. Just to recap - if I raise my saw blade into a bit of wood and cut a few mm into it, it creates a cut that is 3.55mm wide, even though the blade kerf is 3.2mm. When I do my experiment with the alignment gauge I get 0.25mm deviation.

So it seems like my blade runout is between 0.25-0.35mm. I’m wondering if this is acceptable or not?

As I said earlier, it hasn’t been a problem to date but I’m also new to tablesaws so it might be something that becomes a problem down the line as I start doing more detailed/different types of cuts.

the question of whether or not it's acceptable has two facets. One, is it acceptable to the manufacturer, and the other is if it's to you. This must be my first power tool topic in ten years, I think! Only because I had the exact same experience.

I'd go through customer service at carbatec to see if you can find the spec - don't tell them yet what your runout is, but find out how they measure and what the top end of the spec is. I had a pretty much identical amount of runout from delta and they told me the spec over the phone - I was right at the limit with .01" of wobble at the tooth line, then measured with a dial indicator at the flange and was right on their number (.0025"). they weren't terribly interested in offering anything once they knew they were off the hook.

that may be what you find, but it's hard to know without just calling the source.

the amount of wobble was in spec in my case, so the manufacturer was satisfied, but it was aggravating to not be able to use a square to set the TS and then get a square edge. So, I was not.

I've reached out to Carbatec to see what they say is acceptable.

I've done further measurements. I found a test explained online that looks like the below:


I get 0.0015in on the arbor flange (using inches just cause that's what everything online uses). Based on the random references/sites I found (such as this Setting Up a Table Saw & Squaring Crosscut Devices and Fixing the wobble in a table saw arbor) it seems that this should be 0.001" or less. So I'm in slightly out of the "acceptable" range.

(I also noted the relevant comment on the second site: "But really, measuring this is unnecessary. It's mainly for the anal retentives who happen to own a displacement indicator." - so yeah, I know what you're all thinking...).

The second site also suggests that a dial indicator on the blade face should ideally be deviating with 0.002in (0.05mm). Mine, as I said earlier in the thread is more like 0.0075in (0.21mm). So this measurement seems unacceptably high. I get the same measurement across multiple blades. I made sure there are no debris or anything between blade and arbor.

Anyway, that's all the say it seems it could be better. Apparently I can take a grinding stone to the arbor to true it up...I'm not game at this point!

For those asking, I don't know if this is an issue. To reiterate, I'm new to table saws so really have no idea. Cut quality is not just the saw, but also my technique (and probably a myriad other things). Even though I'm happy with the cuts it makes for now, I fully admit I'm a novice. It could well be that in a few years with more experience I realise that there is perhaps an underlying issue with the saw that shouldn't be there given the price point of the saw). But by then warranty is over and I'm stuck. Hence trying to get a better understanding now.

Thanks everyone for the input thus far.

Edit: just to add some context. This is that same saw I posted about a while back where the holes in the cabinet that attach the table were drilled wrong, preventing me from getting the mitre slots even close to square with the blade. Carbatec gave me the go-ahead to bore the holes to give more room to allow me to get it square, which fixed the issue. But this saw hasn't been without issue since I bought it.

Does the needle swing evenly and smoothly or is there a definite “hump”? A hump can be rectified in situ but if it’s even then there is a possibility that the arbor is actually bent or there is some sort of bearing eccentricity. I would repeat that test but at 90 degrees, such as on the ground section of the arbor where the blade sits. That should be practically zero run out. Any further diagnosis probably requires the arbor to be removed entirely and set up between centres and/or vee blocks. For something that small; one and a half thou runout on that flange is appallingly bad manufacturing. Hell; as an apprentice I could file by hand to within two thou…

But; in the greater scheme of things will fixing a 0.25mm run out at the blade tip improve your woodworking? As I stated earlier I don’t regard a table saw as a precision tool anyway; to me they’re just convenient tools for rough dimensioning.