Burned bevels: update with pics

[Dan Forman]

I'm having trouble cutting bevels on my table saw, with blade tilted to 45*, pushing 3/4" stock through with a Jess-Em slider. Saw is set up to tight tolerances, with no burning for any other cuts. I need to cut some 1 1/2 x 3/4" banding for my drill press table, thought this would be the best way to do it. All goes well until the piece gets about half way through the blade, then it burns the top 1/4" or so of the workpiece, not the off cut , only where the teeth stand proud of the blade. It is probably limited to the the top portion of the cut because the sliding table prevents the workpiece from going all the way through the blade. The slider is aligned to the blade so that a five cut check reveals only about .003 on the 5th cut.

It's a fairly new Freud fusion blade, which performs very well on other cuts. I figure the blade must not be aligned to the table in the 45* position, (it's within about .001 or so when 90* to the table) but how does one go about adjusting that? I'll check it with my dial indicator tomorrow. I have a 2 year old left tilt Delta Unisaw. Thanks much.

Dan

[David Cramer]

Hey Dan

Sorry, I don't own the Jessem Slider, but I do own a Unisaw. A left tilt, 3Hp that I've had since 2001. If you're saying you are using the slider and the wood is obviously not butted up to the Beismeyer fence, then I am puzzled. I make 45 degree cuts on the end of boards and actually have them clamped to my mitergauge and get great results. I am not sure why you'd get any burning at all using that system.

I'm not insulting your intelligence, but are you feeding it through the blade at a slower than normal pace? Just guessing. If the blade wasn't aligned perfectly when it was at 45 degrees, I would think that it wouldn't matter at all "as long as the blade itself is flat and true". Puzzling, but I am only a rookie compared to alot of the veteran woodworkers on this site. Hopefully some one will chime in with a better reason/solution. Good luck Dan and I hope it works out for ya.

Dave

[Cliff Rohrabacher]

Squareness is not the test of the slider's adjustment so much as it is the Miter fence's.
A slider should be set up to "V" (taper) away from the blade by some very small amount like .003 or so over a 4 or 5 foot run. Failure to have your slider tapering ever so slightly away from the blade may cause that burning.

Many folks prefer the rip fence to also can't away at a slight taper away from the blade for the same reason.

[glenn bradley]

Dave -- "If the blade wasn't aligned perfectly when it was at 45 degrees, I would think that it wouldn't matter at all "as long as the blade itself is flat and true". "

I think by 'not aligned' Dan is questioning if the parallel alignment to the fence is skewing as the blade is beveled away from 90*. You are correct that if the blade remained parallel, the bevel wouldn't matter.

Dan, I'll look forward to hearing more about the fix. Good luck.

[David Cramer]

Sorry about that Glenn. Your explanation was right on. I had a feeling that I truly wasn't understanding what Dan was asking, but I thought, hey, give it a shot! Such is the mind of a novice:) .

Dave

[Jamie Buxton]

If the blade burns when the blade is tilted over, the trouble may be that the saw front is lower or higher than the rear. My saw did that until I shimmed the front up a bit.

[Bob Wingard]

I think Jamie has the right idea .. .. .. my Grizz. 1023 displayed similar begaviour, and I wound up shimming the top from the base with two nickels and a few thou. brass shim stock. I hope this makes sense, but if the axis of tilt is not parallel with the top of the saw, this is what happens. Move the fence out of the way, tilt your arbor/blade to 45 deg. .. .. .. now, using whatever you do your alignment with, check for blade to miter slot parallelism. I think you'll find it off by a pretty good amount.

[Joe Jensen]

I'm having trouble cutting bevels on my table saw, with blade tilted to 45*, pushing 3/4" stock through with a Jess-Em slider. Saw is set up to tight tolerances, with no burning for any other cuts. I need to cut some 1 1/2 x 3/4" banding for my drill press table, thought this would be the best way to do it. All goes well until the piece gets about half way through the blade, then it burns the top 1/4" or so of the workpiece, not the off cut , only where the teeth stand proud of the blade. It is probably limited to the the top portion of the cut because the sliding table prevents the workpiece from going all the way through the blade. The slider is aligned to the blade so that a five cut check reveals only about .003 on the 5th cut.

It's a fairly new Freud fusion blade, which performs very well on other cuts. I figure the blade must not be aligned to the table in the 45* position, (it's within about .001 or so when 90* to the table) but how does one go about adjusting that? I'll check it with my dial indicator tomorrow. I have a 2 year old left tilt Delta Unisaw. Thanks much.

Dan

Dan, I think that burning is a result of the blade parallelism to the fence changing when going from a 90 degree setting to a 45 degree setting. I think the similar setting on my Dewalt RAS is called "Heel". The new SawStop has an adjustment for this. Take a look at their manual to see if you might figure out a way to shim the saw to accomplish the same thing. Here is a link to the SawStop manual.
http://www.sawstop.com/documents/CabinetSawManualV2.4_000.pdf

[Jamie Buxton]

Here's a thread describing the condition, and the adjustment on a Unisaw.

http://www.sawmillcreek.org/showthread.php?t=15546&highlight=bevel+table

[John Lucas]

If you are using the slider, is your workpiece clamped now tight on it on hand held? If the latter, clamp it down. If clamped down, the slider to blade relationship is not true.

[Gary Keedwell]

Here's a thread describing the condition, and the adjustment on a Unisaw.

http://www.sawmillcreek.org/showthread.php?t=15546&highlight=bevel+table

Jamie....good thread...thanks

Gary K.;)

[Dan Forman]

Sorry I couldn't get back any earlier. Jamie has the picture as far as what the problem is, however there is one other variable here as well.

The saw table has a hump, even with the arbor, running right to left. When I run a dial indicator pointed down and contacting the table, I get a variation of -.006 from the first teeth to midway between the center and the rear teeth. Photo is a reinactment, was actually measured tighter to the blade, with the blade retracted to normal depth.

http://i98.photobucket.com/albums/l279/T-Caster/Woodwork/P1010648.jpg



The indicator reads a -.016 from front to back over the entire blade when run along the right miter slot.

http://i98.photobucket.com/albums/l279/T-Caster/Woodwork/P1010647.jpg

And here is what the burn looks like. Please forgive the picture quality, as these are just to illustrate that which is difficult to state clearly verbally.

http://i98.photobucket.com/albums/l279/T-Caster/Woodwork/P1010649.jpg

By the back of the cut, there is a clear ridge or indentation along the burn line that is close to .006 deep, as measured with a feeler gauge.

Now, for the last confounding variable. I had forgotten all about this actually, but when I first got the saw, I had noticed the hump, and took the top off and brought it to the dealer to show them. I was told it was no big deal, that they all had variations, and that it was within mfg. tolerance. When I went to reassemble it, I noticed that the top didn't make contact at all four corners of the cabinet, and placed a washer between the cab and the top in the right far corner (standing at operator's position). This evened out the contact points.

Tonight after measuring as in the second photo, I removed said washer from between the cab and the top, remeasured, and it cut the variance in half, from -.016 to -.008. But is also gave me a hump on the right side similar to that on the left, as it essentially bent the table down when the bolt was tightened. I made another cut, and it didn't seem to make any difference in the burning, so I put it back in.

That got me wondering if the hump on the left side could be corrected by placing a whasher there? Actually, the ends of the table front and rear on each side slope down a bit in relation to a known steel straight edge. I guess I'll experiment some with that when and if I ever get to finish my current project.

And now, the rest of the story...I was able to get a nice clean cut using the miter fence on the right side of the blade, rather than using the sliding table, so I guess that's what I'll use for now, untill I can get the rest of this figured out.

Dan

[lou sansone]

Squareness is not the test of the slider's adjustment so much as it is the Miter fence's.
A slider should be set up to "V" (taper) away from the blade by some very small amount like .003 or so over a 4 or 5 foot run. Failure to have your slider tapering ever so slightly away from the blade may cause that burning.

Many folks prefer the rip fence to also can't away at a slight taper away from the blade for the same reason.

I agree with cliff on this. have you checked the amount of taper?
lou

[Dan Forman]

Lou---I wasn't aware of that issue when setting it up, but for what it's worth, I get the same burn using the regular miter gauge in the left slot as with the sliding table. And it's not just a burn, but there is a distinct ridge along the arc of the path of the teeth where they have cut ito the bevel.

Dan

[glenn bradley]

I was amazed how flexible cast iron is. I experience this while 'tweaking' my hybrid and extra extension wings. Shimming may be your ultimate answer it will just take a bit of trial and error. I'll hope for the best.

P.s. I was very surprised to find that the manufacturer's tolerance on the top was .01" when I called to complain about .004". I eventually got better.

[Dan Forman]

Over the weekend I leveled the table by inserting 1/16" washers between the cab and table on both rear corners. The result is level within a couple thou, and no more burns. I was able to preserve the table alignment by leaving the front bolts tight, and using a car jack to lift the table enough to insert the washers, one corner at a time. I was surprised and grateful that the first trial got it so close, and that the table didn't shift in the process. Thanks for the help.

Dan

[Jim Becker]

Sounds like the shims normally installed by the factory were, ummm...forgotten. They are critical for proper alignment during bevel cuts as you found out.

[glenn bradley]

Very cool. I love this forum.