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Discussion Starter · #1 · (Edited)
I just built a new cross cutting sled and did the 5 cut test and it's off by .075.

So by that, it means I need to move the left side of the fence back .075 correct?

Thanks
 

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where's my table saw?
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why not test it this way?

Crosscut a 10" piece of stock 2 ft long or so.
Flip the right piece over and mate it with the left side. Does it form a straight line?
If not, the difference divided by 2, is the amount of correction needed in the angle of the fence.
Making 5 cuts there is too much possibility for the work to creep and throw off the cut...just my opinion.
 

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If you make your fence adjustable initially, you can move the fence incrementally until you are satisfied. Then apply fixing screws.






.
That is certainly the best way to make the sled. If it is adjustable it can also be used to make miter cuts. Since I do not do metal work I do not even have an instrument that can measure 00.075

George

PS 00.07 is not very much if it is off that much over 24". If it is over 6" then it is a problem.
 

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Tune your saw first, making sure the blade is parallel to the miter ways. Make sure your sled runners fit with no side to side play. I would recommend using both miter ways, two runners. All you should need to do is raise the blade and put an accurate square against the blade to set your fence by. The 5 cut method gives you 5 potential mistakes and you won't know which one or more than one was a problem. Make separate sleds for 90 and 45 degree cuts. They will be ready whenever you need them with no changes to the set up. A lot can depend on the saw you have and the blade. Sleds and many other fixtures work quite well on quality cabinet saws. That doesn't always translate to lighter duty, portable saws that aren't as accurate or stable in their adjustments. A good, sharp crosscut blade makes a world of difference. A dull blade or taking skim cuts to check your set up can cause the blade and/or work to move slightly and you will never get a true reading. The edge of the stock must be straight or you won't have a true reference to put your square on. Making sleds is very easy but people shoot themselves in the foot by over complicating and using improper techniques shoved down your throat by videos that hobbyists swallow hook line and sinker. If simply using a square doesn't give you an accurate sled, there are other issues at play.
 

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A framing square on each side of the blade should be good enough to locate the fence on your jig. I wouldn't want it be off more than 1/64 (0.0156) over 12 inches....unless you are just rough cutting.
 

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Discussion Starter · #7 ·
Thanks for the info. Everything else was square and parallel. It's just a fence issue. It was .075 off with a 9" piece of stock. I will go down and try and readjust the fence today and see if I can get closer. I am going to buy a large framing square as I don't own one.
 

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Thanks for the info. Everything else was square and parallel. It's just a fence issue. It was .075 off with a 9" piece of stock. I will go down and try and readjust the fence today and see if I can get closer. I am going to buy a large framing square as I don't own one.
Do you own a feeler gauge? You know, the one used to adjust valve lash and spark plug gap.

I have used it in conjunction with a stop block clamped to the end of the table.

To move it forward, place the feeler gauge in position and then clamp the block. Remove gauge, reposition fence. Make another test cut.

To move it rearward, place block against the fence and clamp it. Loosen fence, insert feeler gauge, then retighten the fence. Make test cut again.

At least that is what I was told.
Good luck.
Mike
 

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It is apparent that some of the well-intentioned repliers here aren't familiar with the 5-cut test. It is a method that allows you to magnify the error so you can more easily correct for it. I saw this YouTube video by William Ng, who is a very well respected woodworking instructor, and he has done the best job of explaining it that I have seen any where. You can find it at http://youtu.be/UbG-n--LFgQ
 

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Discussion Starter · #12 · (Edited)
Agreed! So I have been using Williams method following his Youtube video...

Something just seems off....

Here are pictures to better describe.

Table is level.
Blade is level.
Square looks fine on the left side of the blade, flip the square over and the right side shows its off?

My runners are built per Williams instructions, my table is waxed and everything slides smoothly... Just not making any sense. I am using hardwood ply for my sled and fences...

I went out and bought the blue square today as mine is older and i thought maybe it got tweaked over time... Doesn't seem to be the square that's the problem. I get the same results using multiple squares.. Any ideas?

*Edit*

(The only thing I can think of is that my fence system is off.. Since that's what I used to cut the plywood fences, maybe the table saw fence is 1 degree off? I did attach a piece of hardwood to the fence so I can have a sacrificial fence...

That's the only thing that makes sense to me... I have a router table, I could try using my straight bit and edging the one side to see if the problem goes away?)

Ok.... Took the sacrificial fence off of the table saw fence, put the fence to zero and this is what i measured...

.018 was the distance from the right side of the blade and the fence using a feeler gauge. This was the measurement from the blade furthest away from me.
.023 was the distance from the right side of the blade and the fence using a feeler gauge. This was the measurement from the blade closest to me.

So the blade is not tracking correctly.. I assume this is an arbor adjustment?
 

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where's my table saw?
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I watched the video...again

OMG. :eek:
I had to stop before I finished....too much going on. Ten thousands here divided by 4 minus 20 thousands there etc...OMG. My brain hurt. You still need a protractor I think? I donno? Depends on where your fence pivots at also.... Use a feeler gauge....Use a Verier caliper... Measure the cutoff at both ends, subtract the difference, divide by 4....

I suck at math. Just creep up on it if you are like me. I don't know if knowing the angle that you are off will help either...it's off that's all you need to know. More than 90 degrees or less? On which side are you measuring?

Just make a cut, mate the pieces together, adjust the fence, make another cut, until there is no gap when they are laid against a straight edge. It might take a few times, but it will be very freakin' close. Then we have to check it with a square? No, not really. Is your square square? Who knows...? :blink:
 

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where's my table saw?
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The table saw fence don't matter

The saw blade must be parallel to the miter slots, if you measure it accurately. Here's a tip. Use a steel straight edge 24" long or so and snug it right up against the blade's plate not touching any teeth. Measure over to the miter slot with what ever accurate tool you have. The measurement at the front of the table and at the rear of the table to the miter slot should be the same. If not, that's your issue.
Your sled is not tracking parallel to the blade. When you set your sled fence at 90 degrees to the blade and then run the sled in the miter slots it won't be at 90, it will be skewed slightly.

Your sled fence must be perfectly straight also. That could be your issue. When you flip the blue square from right to left it make be on a slight bump. It should track the same line whether it's flipped one way or the other against a straight edge, if not, your square is not square. :eek:
 

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Looks to me like you sled fence isn't perfectly straight. I don't know how else you could get the results you are getting by flipping the square.
 

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where's my table saw?
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10" is not enough

Here is a better picture to describe the difference.

This is over a distance of 10", since that's the blade size...
That's why I suggested using a a long steel scale against the plate of the blade which will effectively extend it 18" or 24" etc. an more accurate method.

The tablesaw fence is not a part of this issue and has no bearing on your sled problem. The fence can be adjusted as a separate issue.
 

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Old School
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Just something to think about. Forget about your saw fence being parallel for a moment. Check both miter slots for parallel. When you mount the sled platen to the runners, it could be made to be adjustable. When you mount the fence(s) to the sled, they only have to be parallel to the blade, and they too can be adjustable.







.
 

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I just built a new cross cutting sled and did the 5 cut test and it's off by .075.

So by that, it means I need to move the left side of the fence back .075 correct?

Thanks
I've read this whole thread and there is TMI.
The 5 cut test is the best.
You don't ever need a square.
It multiplies the angle error 5 times, so moving the fence the same amount will throw it way off.
I didn't watch the video it is too long at my slow net speed.
Take a large panel, cut off 1/8" or so and rotate so each cut is now against the fence.
On the 5th cut take the off-cut strip and break it in half.
Lay both ends together and that is your error X 5.
Move fence accordingly, trial and error until 5th strip is same thickness at both ends.
Make sure to blow any sawdust away from fence each time, even 1/1000" is critical.
This is the way they set up $ $60,000 sliders.
 

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Discussion Starter · #20 · (Edited)
Ok, so the blade was no where near parallel to the mitre slots... It took me forever, had to loosen the front and rear trunions and apply pressure to the right of the front trunion to get the blade parallel.

Ok, problem 1 solved....

I figured I would rotate the blade to make sure everything was working fine before spinning the saw up.

When I move the blade by hand i can feel a metal on metal contact about 1 revolution in. It feels like a sticky spot... Maybe this is why the original owner sold the table saw... Too much work to get this saw accurate?

Any idea what could cause the binding?

All I adjusted was the trunions, nothing else.... I followed the manual.

Any ideas what might be causing the contact? It feels like the shaft/rod that the saw blade attaches to is contacting something (the arbor?). That's the best I can describe it.

Sorry, still learning all the terminology.
 
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