Need Help with Table Saw Cut Issue - Woodworking Talk - Woodworkers Forum
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post #1 of 13 Old 02-11-2018, 06:14 PM Thread Starter
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Need Help with Table Saw Cut Issue

I have a strange issue with the cuts on my table saw. I have an older 3 hp Delta Unisaw. The beginning of any cut has a slight bevel leaning to the right and the back of the cut piece has a slight bevel angle to the left. Itís like there is a twist in the end of a crosscut. This happens with ripping too. I have tested multiple Freud blades and get the same result with each one. I have tried full kerf and thin kerf blades and have tried multiple types of wood. I canít figure out the problem. I have the blade set at 90 degrees and am sure it is set correctly. I use machinist squares and I have a Wixey digital angle finder to set it. My saw blade is parallel to the miter track within .0005Ē and has been rechecked many times with my dial indicator. The blade at 45 degrees is parallel to the miter track within the same tolerance. It was slightly off but I shimmed the front of my table and got it parallel. Runout on the arbor is .003Ē and around .008Ē at the end of the blade. There is no play at all in my arbor when I try to move it. I canít figure this out. The angle is not very severe but it is very easy to see when making shoulder cuts on tenons as this causes there to be gaps. Any help would be appreciated.
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post #2 of 13 Old 02-11-2018, 06:30 PM
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Since it does it with different blades maybe there is something on the washers holding the blades on a slight angle making it wobble a bit. You might also check the arbor shaft. If a bearing is starting to wear out there might be a little looseness in the shaft.
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post #3 of 13 Old 02-11-2018, 06:48 PM
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or some wear/slop in the carriage.

the blade over hangs on the shaft - when feeding a cut the leading edge will want to push back and to the right. any slop/movement - either in the carriage or worn bearings/mounts would do it. perhaps at the outfeed edge it's just 'rebounding' back to vertical.

bumps/humps in riving knife and throat plate can also cause a cut to wobble thru the blade - easy to check tho.
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post #4 of 13 Old 02-11-2018, 07:37 PM
where's my table saw?
 
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The blade is tilting somehow....

If the blade was wobbling the kerf would just be wider. So, it's not the blade or the washers.

Either the carriage is not secured on the trunnions OR the trunnions have a loose bolt OR the table is shifting from feed pressure downward. A Unisaw is a cabinet saw where the table is shifted to align the slots to the blade. Something is loose or worn. Make certain the tilting shaft is "locked" so the trunnions can't shift.

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
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post #5 of 13 Old 02-12-2018, 10:31 AM Thread Starter
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Thank you. I will check the trunnion bolts.
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post #6 of 13 Old 02-12-2018, 10:57 AM
where's my table saw?
 
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Check everything I said

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Originally Posted by Bradross20 View Post
Thank you. I will check the trunnion bolts.
Check all the bolts and lock the tilt mechanism.

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
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post #7 of 13 Old 02-13-2018, 10:48 AM
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Brad, Looking at the photos, it appears your lumber is not flat. Does the lumber you are testing lay flat, with no bows or cups? It could be that as the wood is severed, it is changing it's position on the table as you progress thru the cut.
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post #8 of 13 Old 02-13-2018, 12:29 PM
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agreed, that is not a true enough board to check saw alignment with. maybe flatten/joint on a jointer first. your cut looks like it could be the result of a miter with a loose bar in the slot. is there side to side play with the miter? you can dimple along the sides of the miter with a prick punch to tighten it up.
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post #9 of 13 Old 02-13-2018, 02:57 PM
where's my table saw?
 
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I don't think it's the wood..........


This piece appears to have a slight cup, but because the edges or the convex surface is registering on the table surface it won't create an angle in the cut. The only thing that would cause an angled vertical cut would be a tip upwards along the length OR a shift in the table or the blade/arbor system.

Do not confuse a horizontal crosscut with a miter gauge with an angled vertical cut. Sandpaper glued to the miter gauge face or fence if there is one, will eliminate any shifting laterally of the workpiece.

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
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post #10 of 13 Old 02-13-2018, 03:12 PM Thread Starter
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Thanks for the response. I first noticed this when cutting tenon shoulders in oak suing my crosscut sled. I jointed and planed the oak before using the crosscut sled. I only used the 2x4 because I thought it would be easy to see in the picture.
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post #11 of 13 Old 02-13-2018, 03:37 PM
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you can check if there's movement in the blade/arbor/carriage - - -

make a cut like on the 2x4
then make a second extremely light cut - not more than 1/2 blade width - on the first cut surface
(both pcs)

(as pointed out - the wood stock needs to be flat with no twist...)

if the second cuts line up flat+plumb+square - that's a good indication that the force of moving a pc thru a (heavier) cut is causing the carriage mechanism to move/distort - likely from wear.
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post #12 of 13 Old 02-13-2018, 09:02 PM
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I have to think on the main problem but 003" runout on the arbor is a lot. Mine is less than 0005" on the flange.
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post #13 of 13 Old 02-14-2018, 09:06 AM Thread Starter
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Thanks, I'll give this a try.
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arbor, blade, crosscut, runout, table saw

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