# Are straight edges mythical???



## bcurrey (Dec 6, 2012)

I am fuming at the moment. :furious::furious::furious: I have tried and tried and tried to get a straight edge on some rough cut walnut. I have watched video after video on how to get it. I've measured every angle on every saw that i can think to measure to ensure 90 degree angles. YET STILL, gaps of around 1/16th when I put the two boards together. 

End goal is a walnut table top. 

I tried the table saw jig where you attached the walnut to a straight board and you should come away with a straight edge. 

I 've tried my 4" and 6" jointers. I don't care for the fences, even though they are 90 degrees in every spot i check, still no nice smooth edge. 

I've tried a staight board clamped to the wood and running the circular saw down it. You guessed it - no straight edge when i put to boards together. 

I'm attached 2 pictures. The first i wrote "GOOD" on the edges because they were the 2 boards I checked with my t square and everything seemed great. BUTTTTTT.....looking at the picture, you can see daylight on the other side. 

Second pic, has 1 board that I cut and labeled "Good." Second board has an angle on the edge - BUT THE GAPS LOOKS BETTER THAN THE FIRST TWO BOARDS!?!?!?!?!? 

Anyone have any suggestions. I'm at a loss. Thought I was doing pretty good, now I'm not sure what to do. Should I try to find someone locally that would square them up for me? Where does one find someone? I don't know. I'm open to anything right now. Including walnut firewood. Thanks.


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## GeorgeC (Jul 30, 2008)

Cutting a straight edge on a table saw should be routine. Unless your fence is somehow slipping.

You mentioned a jig. Does this mean that your rough cut wood does not have one side that is essentially straight?

Do you have a problem getting the fence on the jointer 90 degrees to the table? However, that does not seem to be the problem as the gap looks uniform.

Because no method you use seems to work I do not think it is an equipment problem. I think technique must be the gremlin.

George

George


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## MT Stringer (Jul 21, 2009)

I guess if all else fails, you could line up two pieces like pictured, use a straight piece for a guide, and run your circular saw through the boards where the gap is. That should produce a good joint.


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## Tree Hugger (Sep 1, 2011)

Are you using a feather board on your table saw? I don't have on and should , but I use a helper with long boards on the back side to help insure the board stays against the fence.
Short pieces I've had no problem but the long ones I've noticed can walk away if your not careful, then you have a dip in the middle.
Maybe switch to some cheap pine until you get this figured out.


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## woodnthings (Jan 24, 2009)

*two reasons for "gaps'*

First there is a curve in one or both of the boards when looking down from the top or along the edge.

Second, the edge is not square to the surface on one or both boards.

A table saw will replicate a slight curve on a ripped board unless you use a straight line rip jig. I get good results with the jig I made, good enough for gluing using clamps.
"Straight" is a relative term and in woodworking straight enough is often good enough. A variation of 1/32" is the most I would allow in a 4 ft board. You can clamp it well enough to eliminate that amount of variation.

You may be seeking perfection where it is not necessary.... I donno? :blink:


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## Alchymist (Jan 2, 2011)

Try running one board through the jointer with the face against the fence, and the next one with the back against the fence, then see how they match.


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## WesTex (Jan 5, 2014)

You said you're using rough cut walnut. Is the face you run against the jointer fence or table saw flat? If you're using a jig, is it flat, and is the jig edge that runs against the fence straight? If so, then I'd also suspect operator error.


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## bcurrey (Dec 6, 2012)

Thanks for the responses. I stepped away for a while to calm down. :blush:


Yes, I used a feather board on the table saw.

To flatten the face, (the boards were wider than my jointer), I put the boards on a flat board and attached them to the board. Then I put shims there there was an warping, and ran it thru my planer. I started working on the edges once the faces were smooth and straight.

So since this is going to be a table top. How much of a gap can I get away with an cover it up to where it isn't noticeable? I know the glue and saw dust trick, but I've never done it on a piece like a table top.


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## FrankC (Aug 24, 2012)

Hopefully you never use the glue and sawdust trick on a table top.

If all else fails clamp two boards side by side with a gap a bit less than your straight router bit, run the router down the gap against a straight edge making sure both edges are being cut. Even if the straight edge is not perfectly straight the two boards will fit together. Continue one board at a time until the top is glued up.


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## Steve Neul (Sep 2, 2011)

You might need to fine tune your jointer. If the blades are not good and sharp and the rear table not exactly level with the cutting edge of the knives it can drive you nuts trying to make a good joint. 

If the jointer is set up right you can eliminate a gap in the middle by starting the cut in the middle of the board and turning it around starting the cut in the middle again using only the rear table. By doing this you are trimming wood off the ends of the board instead of the middle. If the gaps were on the ends of the joint you could start the board barely on the rear table trimming wood off the middle.


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## was2ndlast (Apr 11, 2014)

Steve Neul said:


> You might need to fine tune your jointer. If the blades are not good and sharp and the rear table not exactly level with the cutting edge of the knives it can drive you nuts trying to make a good joint.
> 
> If the jointer is set up right you can eliminate a gap in the middle by starting the cut in the middle of the board and turning it around starting the cut in the middle again using only the rear table. By doing this you are trimming wood off the ends of the board instead of the middle. If the gaps were on the ends of the joint you could start the board barely on the rear table trimming wood off the middle.


I can't imagine the jointer leaving a curve like that on the edge ...unless the board was bowed to begin with and you apply too much pressure on the infeed table which straightens the board out (making the knives cut along the whole length) and then after pressure is released it springs back into a bow. But since it cut along the whole edge, the bow is maintained.

Ask me how I know.


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## TimPa (Jan 27, 2010)

I suggest that you check the jointer set up.


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## sanchez (Feb 18, 2010)

If you're using a straight line ripping jig for the edges, be sure it fits perfectly (doesn't wobble) in the miter slot and it stays flat on the table.


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## fareastern (Sep 19, 2014)

The knives used to machine the wood in the first photograph were in bad shape,you can see lots of ridges.This alone will be a difficulty.A sharp set of knives and a carefully set up machine will help massively.

So would a sharp No7 plane.


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## hwebb99 (Nov 27, 2012)

In theory yes, but you can get two edges they fit together perfectly as far as the human eye can tell. A jointer can produce a better edge than a table saw, but a table saw can produce an edge far better than that.


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## Tennessee Tim (Dec 15, 2010)

I see several possible issues and some things that have nothing to do with the gap..... 
1st ...90 deg has NOTHING to do with this issue...this is a straight line issue...90 deg only effects the flatness the boards are going to glue in the perpendicular/opposite plane.

2nd ...you didn't mention the length of the top....a 1/16 th is nothing for a glue line in 8 ft but is awful for a 18" length

3rd... HOW was this wood dried???? and is it straight grained or more wavy /knotty as one pic shows???
Drying too fast causes fatique in wood and when ripped it reacts with more warping and bowing....sometimes called casehardening.
If the wood is more knotty/ wavy grained than it's harder to keep the wood from moving as it's ripped. some older woodworkers were known to cut/rip oversize then thinly rip/joint to final specs to prevent the least movement flipping from side to side.

4th... the jointer is the best way BUT like all equipment it has limitations and varies in quality... the longer the bed the easier to be flatter/straighter. As other equipment it still needs precise set-up to do it's best job....IF the blades aren't sharp or the alignment correct it will crown or cup the desired straightline and cause this issue.

5th...did you dry the opposite edge/flip to see if it's just a bow/crown and it would work...that would tell you it's in the wood if one side is bowed in and the other bowed out.

6th... is it at the correct MC 7-9%

edit: reread post #8....your blades are DULL!!!! according to the face in one of the pics and you mentioned the wood is warped.


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## woodnthings (Jan 24, 2009)

*hold on there partner....*

The angle on the edge, whether it is 90 degrees or not, and of the mating edge has everything to do with whether there is a gap or not. You can NOT mate an 89 degree edge with a 90 degree edge and not have a gap on one side of the boards. This is why when jointing, you should rotate the next board end for end. This insures that any variation of the fence from 90 degrees with be accounted for... 










Assuming lines AB and CD are parallel, angle AGH is equal to angle DHF whether they are at 90 degrees are not. A rip on the table saw would mate with another board IF the second board was flipped end for end, even IF the blade was not at 90 degrees. Hope I'm making this clear...?

To mate 2 boards without a gap and without flipping would require they both be exactly at 90 degrees.


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## Tennessee Tim (Dec 15, 2010)

The gap his pics show are caused from length tips or such touching...you can see all the way through. IF it were a degree issue they would touch let's say on the bottom and not the top edge if laying flat and you couldn't view/see through....kinda like a V exaggerated. This causes a completely different issue.

edit: I can take 2 boards with 87 deg angles that are true straightlined and lay them correctly and have a gap free and flat surface after glueing.


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## woodnthings (Jan 24, 2009)

*that's what I was sayin'*

When you say "lay them correctly" that's exactly what I was trying to explain. :yes:


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## Tennessee Tim (Dec 15, 2010)

woodnthings said:


> When you say "lay them correctly" that's exactly what I was trying to explain. :yes:


I'm with you though.....true 90 degrees makes life MUCH simpler!!!!:laughing:


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## woodnthings (Jan 24, 2009)

*there may be an occasion where ....*

Let's, say you tip your table saw over to 85 degrees or 5 degrees on the scale. Now you lay out all your boards "good side up" and you makes pencil marks across all of them. Next you turn every other one over and rip them. There will be no mistaking which boards mate with the others because of the angle.


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## was2ndlast (Apr 11, 2014)

To the op, did you figure it out?


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## bcurrey (Dec 6, 2012)

Thanks for all the responses. This has been very informative! 

I've only been able to get into the shop for a few mins this week. However, I borrowed a friend's Bora straight edge ripping clamps. They were a bit frustrating to setup at first, and I didn’t have high hopes, but they worked pretty well! 

I ripped two boards on 1 edge on then placed them together. No gap! Below is a pic. 

After reading the comments from everyone, I think the issue is my jointer. When I put the Bora clamps on the jointed edges, both of the boards had small variances near the middle of the boards, which would explain why the table saw wasn’t lining up correctly. 


Now that all indications are that I finally have a straight edge, I’m going to run a board thru the table saw tonight to straighten up the other side and then see how square the board comes out. 

This table table is going to be 7ft long, so I'm hoping this is my last straight edge hurdle! 

Again, really appreciate all the help on this.


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## Tennessee Tim (Dec 15, 2010)

Glad to see you've resolved the issue!!!! Make us some pics of the beautiful walnut as you build!!!!


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