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Rear fence difference from front

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Forum topic by JonC123 posted 07-01-2018 07:07 PM 832 views 1 time favorited 10 replies Add to Favorites Watch
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JonC123

10 posts in 428 days


07-01-2018 07:07 PM

I’ve read the rear of the fence should be out (away from the blade) a bit to prevent pinching the work piece.

I’m still not sure what tolerances are “good enough” for woodworking. It’s currently off by around 5 thousands, should I make it around 10?

I just cut of a 4’ piece and there was 1/64 difference from one end of the board to the other. When I made it into a box, there’s now a lip on of the corners because of the difference.. not a big deal as I can sand it.

Just trying to find a good balance


10 replies so far

View WhyMe's profile

WhyMe

1153 posts in 1954 days


#1 posted 07-01-2018 07:41 PM

Go with parallel or a thou or so out. Just don’t let the rear of the fence have any inset to the blade.

View Kazooman's profile

Kazooman

1318 posts in 2346 days


#2 posted 07-01-2018 07:50 PM

There was a thread on this exact topic recently, but I can’t find it using the search function. The problem with having the rear of the fence adjusted farther away from the blade comes on the rare occasion when you want to use the saw with the fence on the other side of the blade. Then the work piece would get pinched possibly leading to a kickback.

I found it:

http://lumberjocks.com/topics/278921

View TheFridge's profile

TheFridge

10858 posts in 1879 days


#3 posted 07-02-2018 03:13 AM

5 thou is plenty for me. I wouldn’t do any more than that.

If your board is tapering then it’s a technique problem. My guess is you’re putting too much pressure on the fence and either the beginning or end of the cut.

What kind of fence do you have?

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

View Rich's profile

Rich

4491 posts in 983 days


#4 posted 07-02-2018 04:10 AM


5 thou is plenty for me. I wouldn’t do any more than that.

- TheFridge

Yeah? I’ll see your five thou and up you a millionth. The pot now stands at 0.005001.

It’s your move. Do ya feel lucky?

-- Knowledge is not skill. Knowledge plus ten thousand times is skill. -- Shinichi Suzuki

View JonC123's profile

JonC123

10 posts in 428 days


#5 posted 07-02-2018 11:54 AM



5 thou is plenty for me. I wouldn’t do any more than that.

If your board is tapering then it’s a technique problem. My guess is you’re putting too much pressure on the fence and either the beginning or end of the cut.

What kind of fence do you have?

- TheFridge

I think this is because my fence is around 10 thou in the center but 5 at both ends.. Will have to figure that one out

View jonah's profile

jonah

2075 posts in 3692 days


#6 posted 07-02-2018 03:00 PM

I always try to get it as straight as I can, but if I err, I err on the side of outward at the back rather than inward.

View BroncoBrian's profile

BroncoBrian

875 posts in 2352 days


#7 posted 07-02-2018 03:14 PM

JonC123

I did some testing on this after that last thread linked above.

If your cut is off 1/64th, then you have a technique issue, or your table or blade is off. The fence alignment question should not be the cause of that.

I ran a few cuts of good plywood with the fence 1/128th in, dead on, 1/128th out, 1/64th out, and even 1/32 out. Then checked all of the cuts.

Having the fence in (with precautions!) was not good, even that small distance. The wood had burn marks as expected. With a bad blade, this could have gone poorly.

The other options rendered the same even width cut result. The cut is made by the leading teeth at the front of the blade, that is where the distance to the fence and the blade will determine the width of the cut. I am learning that the pressure on the board as you move it needs to be placed feeding the board in and just out of the blade. Forcing the board into a fence at the back end of the fence does not do any good.

Have you tried to repeat the same cut 4 or 5 times to see if you have the identical error? Seems like a waste of material, but it is worth knowing.

-- A severed foot is the ultimate stocking stuffer.

View Markmh1's profile

Markmh1

105 posts in 837 days


#8 posted 07-02-2018 05:40 PM

Yeah, it sounds like somethings moving to be out 1/64th.

As a test, you might want to push on your fence similar to cutting pressure with your indicator on the fence. If your fence moves, this may be part of the problem.

Mark

View JonC123's profile

JonC123

10 posts in 428 days


#9 posted 07-02-2018 11:53 PM



JonC123

I did some testing on this after that last thread linked above.

If your cut is off 1/64th, then you have a technique issue, or your table or blade is off. The fence alignment question should not be the cause of that.

I ran a few cuts of good plywood with the fence 1/128th in, dead on, 1/128th out, 1/64th out, and even 1/32 out. Then checked all of the cuts.

Having the fence in (with precautions!) was not good, even that small distance. The wood had burn marks as expected. With a bad blade, this could have gone poorly.

The other options rendered the same even width cut result. The cut is made by the leading teeth at the front of the blade, that is where the distance to the fence and the blade will determine the width of the cut. I am learning that the pressure on the board as you move it needs to be placed feeding the board in and just out of the blade. Forcing the board into a fence at the back end of the fence does not do any good.

Have you tried to repeat the same cut 4 or 5 times to see if you have the identical error? Seems like a waste of material, but it is worth knowing.

- BroncoBrian

Thanks for the research and help. I’m new to woodworking so probably paying more attention to the blade than anything else right now :)

I guess I was pushing the board against the fence too hard. I tried again used my left hand as more of a feather-board instead of pushing on it and that seemed to have helped.

I used my caliper and measured 5 1/4 on one end, 5 29/128 in the middle, and 5 31/128 on the other end.

So much closer than before. Does this sound like a normal cut or should it be the same size all the way down exactly?

I’ve used my dial indicator on the blade and it’s only off by 1 thou front to back.

View Sludgeguy's profile

Sludgeguy

56 posts in 516 days


#10 posted 07-03-2018 02:00 AM

I put a Forrest blade on my table saw and had the fence dead parallel to the blade. Burned a little. Went back and read the directions from Forrest and discovered that they suggest having the fence out around 0.005”. I adjusted the fence and it fixed the burning. Cuts are accurate and smooth.

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