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Weird tablesaw cut problem

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Forum topic by Rick M. posted 04-03-2013 04:52 PM 1616 views 0 times favorited 42 replies Add to Favorites Watch
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Rick M.

4509 posts in 1133 days


04-03-2013 04:52 PM

Topic tags/keywords: delta tablesaw troubleshooting question bad cut

My 15 year old Delta contractor has developed a strange problem. Every so often when cutting through the middle of a board the blade will give a little wobble. It happens at regular intervals, maybe every 3 seconds. It’s very obvious on my full kerf rip blade and it may be happening on my thin kerf combo blade but it’s hard to tell.

If it is the blade, wouldn’t it happen almost constantly? Unfortunately I don’t have a dial indicator to check the blade but since it only happens once out of every couple hundred rotations it might be impossible to measure.

It’s hard to describe and too subtle to photograph but you can hear it. Here is an exaggerated drawing to show what I mean. It might happen 3 times on a 4 foot cut.

-- http://thewoodknack.blogspot.com/


42 replies so far

View Hammerthumb's profile

Hammerthumb

1500 posts in 728 days


#1 posted 04-03-2013 05:11 PM

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

-- Paul, Las Vegas

View bondogaposis's profile

bondogaposis

2760 posts in 1104 days


#2 posted 04-03-2013 05:13 PM

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

15817 posts in 2971 days


#3 posted 04-03-2013 05:16 PM

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 2401 days


#4 posted 04-03-2013 05:18 PM

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

425 posts in 655 days


#5 posted 04-03-2013 05:24 PM

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

163 posts in 750 days


#6 posted 04-03-2013 05:24 PM

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

1479 posts in 1114 days


#7 posted 04-03-2013 06:33 PM

There’s a bunion on the trunnion.

-- Clint Searl....Ya can no more do what ya don't know how than ya can git back from where ya ain't been

View IrreverentJack's profile

IrreverentJack

724 posts in 1596 days


#8 posted 04-03-2013 06:46 PM

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

511 posts in 2070 days


#9 posted 04-03-2013 06:55 PM

Clint gets the prize for comment of the day!

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

View Rick M.'s profile

Rick M.

4509 posts in 1133 days


#10 posted 04-03-2013 07:38 PM

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.

-- http://thewoodknack.blogspot.com/

View Grandpa's profile

Grandpa

3211 posts in 1428 days


#11 posted 04-03-2013 07:51 PM

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

3698 posts in 760 days


#12 posted 04-03-2013 07:52 PM

”@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.

4509 posts in 1133 days


#13 posted 04-03-2013 10:19 PM

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.

-- http://thewoodknack.blogspot.com/

View CarpenterMark's profile

CarpenterMark

4 posts in 635 days


#14 posted 04-03-2013 11:56 PM

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

1221 posts in 1377 days


#15 posted 04-04-2013 12:09 AM

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

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