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View Rick M.'s profile

Weird tablesaw cut problem

by Rick M.
posted 515 days ago


42 replies so far

View Hammerthumb's profile

Hammerthumb

1222 posts in 611 days


#1 posted 515 days ago

Check your belts. Might need replacing. See if they have any glazed spots on them.

-- Paul, Las Vegas

View bondogaposis's profile

bondogaposis

2497 posts in 987 days


#2 posted 515 days ago

Yeah, that was my thought too. Check the belt and pulley’s. Make sure the pulley’s are not slipping.

-- Bondo Gaposis

View CharlieM1958's profile

CharlieM1958

15693 posts in 2854 days


#3 posted 515 days ago

My first thought would be arbor bearings, although I would not expect the problem to occur at such regular intervals.

Here is a discussion you might find helpful.

-- Charlie M. "Woodworking - patience = firewood"

View PurpLev's profile

PurpLev

8476 posts in 2284 days


#4 posted 515 days ago

like the others suggested my first guess would be the belt.

if you can HEAR it – then take the belt off, and power up the saw and LISTEN. if you can still hear it then it’s the motor shaft bearings or the motor winding. if you can’t hear it then it’s most likely the belt (or the blade arbor). try replacing the belt and see if it clears it.

-- ㊍ When in doubt - There is no doubt - Go the safer route.

View Airspeed's profile

Airspeed

421 posts in 538 days


#5 posted 515 days ago

Does it do it without cutting? Something is making the blade resonate, try a different blade, if it still does it you have a belt prob or the arbor is bad. I had this happen to my Unisaw, it turned out to be the nut, it was threaded crooked and putting more pressure on one side of the blade. My wife was helping me rip some long stock once and kept moving the boards to the side, it heated up the blade so much that it was ruined and did the same thing you describe, has your blade gotten hot recently?

-- http://smg.photobucket.com/albums/v655/aaronhero/

View Fettler's profile

Fettler

117 posts in 633 days


#6 posted 515 days ago

Do you hear the motor slowing when that happens? Could it be that the wobble happens when you hit a denser bit of wood (a shadow of a knot)? Is there any noticeable play in the arbor?

That sounds like a pain to diagnose.

-- --Rob, Seattle, WA

View Clint Searl's profile

Clint Searl

1431 posts in 997 days


#7 posted 515 days ago

There’s a bunion on the trunnion.

-- Clint Searl.............We deserve what we tolerate

View IrreverentJack's profile

IrreverentJack

724 posts in 1479 days


#8 posted 515 days ago

Have someone watch the motor to see if you have a bounce – If your belt is too short or slipping the motor pulley can walk up the belt when you have blade resistance then drop down. If you stop the cut, does it stop? -Jack

View Mark Davisson's profile

Mark Davisson

489 posts in 1953 days


#9 posted 515 days ago

Clint gets the prize for comment of the day!

-- I'm selfless because it feels so good!

View Rick M.'s profile

Rick M.

3892 posts in 1016 days


#10 posted 515 days ago

It only happens when cutting in the middle of a board, ripping or crosscut. When I say I can hear it, I mean I can hear the blade dig deeper into both side of the cut, sometimes causing a burn, everything else sounds normal. I cleaned the blade and checked all the extension tables for flush/level but it still happened.

It does not happen when: not cutting, cutting on the edge of a board, or taking light cuts. I inspected the belt recently and there is no fraying, hazing or bumps, it looks fine but I won’t rule it out.

@PurpLev – Something is making the blade resonate

Yes, well put. Something is causing a momentary resonance when cutting inside a piece. I made a new zero clearance insert on the off chance that my factory insert (which I normally use with the rip blade) is bobbling and causing the wood to shift. I’m getting ready to go test it.

-- |Statistics show that 100% of people bitten by a snake were close to it.|

View Grandpa's profile

Grandpa

3107 posts in 1311 days


#11 posted 515 days ago

My first thought was heat. That is usually caused by a dull blade.
My second thought is a slipping belt or a slipping pulley.

View JoeinGa's profile

JoeinGa

3190 posts in 643 days


#12 posted 515 days ago

”@PurpLev – Something is making the blade resonate”

Yep, and I’m guessing it’s HEAT. The deeper you cut into the wood, the hotter the blade gets. I think the heat is causing the blade to actually warp. And then as the blade slows it cools, making the blade stiffer again. Any chance you checked the blade for very small cracks? Heat would cause those to “open up”, thereby pushing the blade out of true.

-- Perform A Random Act Of Kindness Today ... Pay It Forward

View Rick M.'s profile

Rick M.

3892 posts in 1016 days


#13 posted 515 days ago

Heat would make sense except it was my first cut of the day, through 4’ of 1/2” MDF so I can’t imagine that was the problem. I installed a splitter hoping it would fix the problem but after switching to a new zero clearance insert and installing the splitter it only happened once in a 4’ cut but it still happened. The blade isn’t very used, freshly cleaned, is relatively sharp. I was just up under the saw yesterday and didn’t see any problems. Tomorrow I’ll switch to a full kerf combo blade and see if it still happens. If the other blades cut fine I’ll send this one out for a sharpening/rebalancing.

-- |Statistics show that 100% of people bitten by a snake were close to it.|

View CarpenterMark's profile

CarpenterMark

4 posts in 518 days


#14 posted 515 days ago

I’t’s the result of an overfeed with a less than sharp blade; slow down the feed and see if it stops.

-- Grow it, make it or catch it!

View jumbojack's profile

jumbojack

1176 posts in 1260 days


#15 posted 515 days ago

I am thinking a blade resharpen. You get the plus of a nice clean blade and I think it will cure your woes.

-- Made in America, with American made tools....Shopsmith

View HR222's profile

HR222

5 posts in 516 days


#16 posted 515 days ago

You may have a blade spindle shaft bearing issue. Or possably a rear motor armature bearing.
This can cause weird blade runout as they load and unload. I hope I’m not being to technical, I’m not
familiar with your model but if your model is direct motor drove to the blade. then the magnetic field
in the motor can cause armature pulse when bearings [wheather bronze or roller] are worn.

View distrbd's profile

distrbd

1078 posts in 1082 days


#17 posted 515 days ago

I would also suspect the blade being the problem,try another sharp blade ,if you eliminate the blade as the source then my next guess would be the arbor shaft,you may need to replace the bearing.

-- Ken from Ontario

View Rick M.'s profile

Rick M.

3892 posts in 1016 days


#18 posted 513 days ago

Okay, it’s just that blade, it’s not dull, and feed rate makes no difference. It also makes a very high pitch noise which I didn’t notice yesterday wearing hearing protection. So I’m going to contact Freud and see what they suggest before I plunk down $10 for sharpening/balancing.

-- |Statistics show that 100% of people bitten by a snake were close to it.|

View TopamaxSurvivor's profile

TopamaxSurvivor

14727 posts in 2312 days


#19 posted 513 days ago

My money is on a bearing starting to go.

-- "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View History's profile

History

395 posts in 617 days


#20 posted 513 days ago

I’d be suprised if it was a bearing, his saw looks too new. It’s got to be something simple. Is there anything in the owners manual about it in the trouble shooting section ?

View MattinCincy's profile

MattinCincy

128 posts in 1789 days


#21 posted 513 days ago

I used to have the exact same problem with my last saw – a Jet Proshop. When I upgraded to my cabinet saw, the problem went away. I always attributed it to a lack of power.

-- Wag more, bark less.

View History's profile

History

395 posts in 617 days


#22 posted 513 days ago

Matt, a Cabinet table saw is not appropriate or even necessary for every shop. If you had a lack of power problem, it wasn’t because of the saw. There are numerous things that it could of been. The saw not plugged into a sufficient electrical circuit and or extension cord, pulleys not aligned, not using the correct blade for the job, a dull blade, a fence that is out of parallel, the tilt hand wheel lock not tightened, etc. I bought a new Delta Contractor’s table saw with a 30” Unifence almost 20 years ago, it’s been a great saw for my shop.

View SamuraiSaw's profile

SamuraiSaw

450 posts in 600 days


#23 posted 513 days ago

If you had a lack of power problem, it wasn’t because of the saw”

Talk about not having a clue…......

Have you ever used anything besides a contractor saw?

-- Artisan Woodworks of Texas.... www.awwtx.com

View GROOVY56's profile

GROOVY56

16 posts in 555 days


#24 posted 513 days ago

I would check the bearings,, thrust and radial play

View TopamaxSurvivor's profile

TopamaxSurvivor

14727 posts in 2312 days


#25 posted 513 days ago

I have never seen that with my little 3/4 hp contractor saw.

-- "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View Rick M.'s profile

Rick M.

3892 posts in 1016 days


#26 posted 513 days ago

What if it’s not a saw or blade problem but a power supply problem? When I shut the saw off it vibrates a little. The full kerf blade would take a little more oomph than the thin kerfs, if the power wasn’t steady it could lose speed for a moment causing the vibration.

-- |Statistics show that 100% of people bitten by a snake were close to it.|

View unbob's profile

unbob

388 posts in 539 days


#27 posted 513 days ago

The motor shuttering to a stop is normal for many single phase motors.
Having a Rockwell 10” contractors saw for 20 yrs, I have had quite a few problems with it, but have sorted the worst of them out.
I am not sure just when my saw was made, it uses the same arbor bearings as the Unisaw.
Some later saws used “of all things” a water pump shaft and bearing. The shaft and bearings are an integrel unit “no longer available”, but a replacement can be found and machined to fit.
The later, are more likely to go out.
At one point, my saw, the thin bearing retaining nut behind the arbor flange loosened, causing the arbor to shift slightly. this nut is threaded into the casting. This nut can only be adjusted with the arbor removed.
A way to check that simply, would be to use a feeler gage, or even a strip of wood that fits between the fixed flange and the arbor bracket, then tap on the ends of the shaft with a soft face hammer, and see if the gap gets wider or narrower.
There is also “on my saw” a bearing retaining nut at the pulley end “threaded to the shaft”.
One more, On my saw, the arbor casting is retained to the works by a short shaft. On the arbor casting there is a square head bolt that keeps the shaft in place. At one point this came loose, and the shaft drifted almost all the way out. There is a wave washer on that shaft to take up play. If that is coming loose, the blade can drift.
From the drawing provided, I tend to think its a mechanical problem.

View History's profile

History

395 posts in 617 days


#28 posted 513 days ago

I think that it’s either a blade problem,dull, gummed up, or he is cutting some really bowed and or wet wood, and isn’t reading the board before running it through the saw. Without being there to look things over we could guess allday.

View bannerpond1's profile

bannerpond1

231 posts in 535 days


#29 posted 513 days ago

Check to see if your arbor is worn so that there is slop in the fit of the 5/8 diameter blade hole. Does the blade act like this when it’s not under load?

-- --Dale Page

View History's profile

History

395 posts in 617 days


#30 posted 513 days ago

Ok folks, here is the link to Rick's workshop, his saw hardly looks worn out to me, infact it looks like new. I don’t suspect anything on the machine is wore out, except for maybe the blade.

View knotscott's profile

knotscott

5434 posts in 2012 days


#31 posted 513 days ago

If it only happens with that blade, the blade may have lost its tension causing it to oscillate. You might even try it on another saw to see if it still does it. Not sure if resharpening would help with that if that’s what’s happening. I’d speak to an experienced sharpener to see what they suggest. $15 for a resharpening is pretty reasonable if it solves the problem, otherwise even a new 24T FTG full kerf blade isn’t too expensive.

The minor shudder at shut down is known as regeneration. It’s common, harmless, and is caused by an electrical interaction with the caps when the motor winds down. It shouldn’t be the cause of a problem during operation.

-- Happiness is like wetting your pants...everyone can see it, but only you can feel the warmth....

View Rick M.'s profile

Rick M.

3892 posts in 1016 days


#32 posted 512 days ago

Hopefully Freud responds to my email but they will probably want me to send the blade to one of their authorized sharpeners and with shipping it’s not really worth it.

-- |Statistics show that 100% of people bitten by a snake were close to it.|

View GaryL's profile

GaryL

1074 posts in 1466 days


#33 posted 512 days ago

Are you tightening the arbor nut sufficiently? By the look of the mark on the blade towards the center it appears to be spinning on the arbor .

-- Gary; Marysville, MI...Involve your children in your projects as much as possible, the return is priceless.

View History's profile

History

395 posts in 617 days


#34 posted 512 days ago

Good eye Gary.

View Rick M.'s profile

Rick M.

3892 posts in 1016 days


#35 posted 512 days ago

That mark is from the blade flange/washer between the blade and arbor nut. It probably turns a little bit as I tighten the nut.

Today I installed a link belt and the difference is incredible, like a new saw; much quieter and smoother. It didn’t fix the blade issue entirely although it reduced it a lot. Before it would wobble about once in every 12” of cutting, after it happened once in 12’ of cutting. When I cleaned the blade I could only get the sides, the face of the teeth still have some pitch. Tomorrow I’ll look for a brush with longer bristles that will let me get down in there and clean more thoroughly. I dread it, but maybe I need to pull the saw top and clean the inside very thoroughly. Maybe a good tune up will put this problem to bed.

-- |Statistics show that 100% of people bitten by a snake were close to it.|

View SamuraiSaw's profile

SamuraiSaw

450 posts in 600 days


#36 posted 512 days ago

Using a full kerf blade may be a part of your problem as well. Contractor saws have limited capacity, and that is why the thin kerf blades have become popular. Until, or unless, you upgrade to a bigger saw I’d stay with the thin kerf.

-- Artisan Woodworks of Texas.... www.awwtx.com

View History's profile

History

395 posts in 617 days


#37 posted 512 days ago

My saw handles a full kerf just fine, yours should be able to also Rick. I’m pretty sure that they both have the same motors.

View Rick M.'s profile

Rick M.

3892 posts in 1016 days


#38 posted 512 days ago

I ran this blade and other full kerf blades with no problem. It’s only recently this developed. It’s possible that at some point in the past I didn’t tighten the blade enough but I think if the blade were really slipping it would have worn through the teflon coating pretty quick. There’s no sign of red on the flange.

-- |Statistics show that 100% of people bitten by a snake were close to it.|

View oldnovice's profile

oldnovice

3718 posts in 2004 days


#39 posted 512 days ago

Rick, some of those coatings do not wear through but rather “slide” over the top of themselves and do not look like typical wearing off like paint does and it is possible that they might have built up in one place causing the type of symptom you were experiencing.

Your remark about the power twist belt reminded me when I replaced my old belt on my saw … it was like a new saw. When I replaced the cast pulleys with turned pulleys the vibration and “humming” totally disappeared and that was some 30 years ago!

-- "I never met a board I didn't like!"

View Rick M.'s profile

Rick M.

3892 posts in 1016 days


#40 posted 512 days ago

Luckily my saw already has machined pulleys, part of the Limited Edition upgrade. So many people recommended the link belt and I was stubborn and put off buying one for years but it really makes a drastic difference.

-- |Statistics show that 100% of people bitten by a snake were close to it.|

View scotsman9's profile

scotsman9

134 posts in 525 days


#41 posted 512 days ago

Since you describe a basic frequency of the odd effect you are getting during your cut, I would suggest (after ruling out mechanical issues), you check your motor and power supply.
I’m reading your issue and thinking it sounds an awful lot like torsional vibration, which can be caused by a current or sine change during the loading of the motor. This would give you the “timed” anomaly you describe.

Just a hunch, but a good excuse to bust out your multimeter and do some math. LOL sounds fun huh?

-- Just a man and his opinion.

View Rick M.'s profile

Rick M.

3892 posts in 1016 days


#42 posted 511 days ago

If a tune up doesn’t fix things, I’ll bust out the calculator, heh.

-- |Statistics show that 100% of people bitten by a snake were close to it.|

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