LumberJocks

How many cauls for table top?

  • Advertise with us

« back to Joinery forum

Forum topic by Travis posted 06-23-2020 09:35 PM 738 views 1 time favorited 40 replies Add to Favorites Watch
View Travis's profile

Travis

465 posts in 576 days


06-23-2020 09:35 PM

Hi all,

I am getting ready to glue a table top. This is my first time doing a panel this large. I went back and forth on using dowels or clamping cauls to make sure my alignment is good and finally settled on the clamping cauls. So the next question is, how many sets should I prepare?

The tabletop will be approximately 40” x 78”. I used a planer sled to get the two faces parallel, so I cannot guarantee that my lumber is perfectly flat, but the sled seemed to work in removing any significant twist or cup, and all are milled to the same thickness.

I’ve used 2-3 cauls on smaller projects, but I’m sure more would be recommended for a large panel. Those of you who use cauls, what do you do? Every foot? More or less?

Also, I’ve never seen a definitive statement about when to tighten the cauls. Before or after the clamps? It seems like whichever you tighten first will make it that much harder for the other…...

-- The plan is wrong; my finished piece is right.


40 replies so far

View JackDuren's profile

JackDuren

1260 posts in 1769 days


#1 posted 06-23-2020 09:39 PM

I don’t really use cauls. I alternate every foot but you can only do with what you have….I usually put two close to gether on the ends to keep it flat…

View nickbatz's profile

nickbatz

532 posts in 890 days


#2 posted 06-23-2020 10:01 PM

Speculation since I’ve never made a tabletop that large or used cauls, but I’d say how many cauls depends on how straight the wood is to start with.

As to when to tighten them, well, right away, no? Why wouldn’t you want the boards to be aligned when the glue is drying?

View Travis's profile

Travis

465 posts in 576 days


#3 posted 06-23-2020 10:45 PM



As to when to tighten them, well, right away, no? Why wouldn t you want the boards to be aligned when the glue is drying?

- nickbatz

What I meant was which do you tighten first? If you tighten the cauls first, can all that downward pressure prevent the lateral clamps from sealing the joint? If you tighten the lateral clamps first, I don’t think the cauls are strong enough to then enforce the desired alignment.

-- The plan is wrong; my finished piece is right.

View JackDuren's profile

JackDuren

1260 posts in 1769 days


#4 posted 06-23-2020 11:08 PM

tighten the cauls to get it flat , then tighten the clamps…

View Aj2's profile

Aj2

3190 posts in 2608 days


#5 posted 06-23-2020 11:28 PM

How did you prepare the edges square to the faces. You don’t mention what wood it is or how thick.
I don’t cauls never need to because I have a very accurate jointer. I do use spring clamps on just the ends.
The thicker and wider boards get the more clamping pressure. Last thing you want is glue lines showing up 2 weeks after you last coat of finish.

Good Luck

-- Aj

View CWWoodworking's profile

CWWoodworking

890 posts in 989 days


#6 posted 06-23-2020 11:38 PM

How thick? Are you running it through a sander after or flattening it by hand?

I don’t use cauls either, but not saying they don’t work. I would tighten before clamps.

Panels that size, I always start in the middle and put enough downward pressure to get any little twist or bow out. Then work towards the ends. That way your working with 3’ instead of 6’.

View Jamie Bush's profile

Jamie Bush

28 posts in 1582 days


#7 posted 06-24-2020 12:31 AM

Be sure to do a test fit up using your cauls and clamps. This will give you an idea of what it’s going to take to get it looking “good”. You’ll know if you need more and how spaced they’ll need to be.

-- A practicing woodworker sounds a lot better than a practicing MD

View CaptainKlutz's profile

CaptainKlutz

3377 posts in 2304 days


#8 posted 06-24-2020 05:04 AM

...
I used a planer sled to get the two faces parallel, so I cannot guarantee that my lumber is perfectly flat, but the sled seemed to work in removing any significant twist or cup, and all are milled to the same thickness.
...
- Travis

It takes flat boards to make a flat table top.
Or put another way: You can not clamp flat twisted/warped boards to make a flat table top.

If your boards do not lay flat to each other when laid out on table side by side, and need top and bottom pressure to ‘make’ them flat; will most likely have hills and dips in top when clamps are removed.
BTDTGTTS

+1 With flat boards to start, you don’t really need clamping cauls. Like others posted before, I alternate my clamps top/bottom and only occasionally need to use spring clamps to keep outer ends aligned on flat boards.

Best Luck.

-- If it wasn't for bad luck, I wouldn't have no luck at all, - Albert King - Born Under a Bad Sign released 1967

View Robert's profile

Robert

3807 posts in 2290 days


#9 posted 06-24-2020 02:28 PM

I agree with Jack, cauls are not necessary. The key to a panel glue up is flat boards and perfect joints.

My technique is to gradually increase clamp pressure, and bring seams into alignment with a rubber mallet. I put clamps on the seams at each end.

If I’m dealing with some minor bows I know I can clamp out, I’ll use biscuits.

That said, if you’re using cauls, I would put them eveyr 12”.

-- Everything is a prototype thats why its one of a kind!!

View Travis's profile

Travis

465 posts in 576 days


#10 posted 06-24-2020 02:41 PM


tighten the cauls to get it flat , then tighten the clamps…

- JackDuren

Thank you!


How did you prepare the edges square to the faces. You don’t mention what wood it is or how thick.
....
- Aj2

I used a router with a straight edge (factory edge of sheet of BB plywood) to get one good edge that is square to the face. I’m hoping to get the second edge on my TS today, but if I can’t get a glue line rip with the TS, then I’ll use the router on the second edge.


How thick? Are you running it through a sander after or flattening it by hand?
...
- CWWoodworking

Ash milled down to 1”. I was hoping for a bit more but one of my wide planks had significant twist, I lost of lot of thickness getting that piece flat. After glue-up will be flattening by hand (ROS). So my desire for a flat, aligned glue-up is both to preserve as much thickness as possible and to minimize my labor afterward.


It takes flat boards to make a flat table top.
Or put another way: You can not clamp flat twisted/warped boards to make a flat table top.

If your boards do not lay flat to each other when laid out on table side by side, and need top and bottom pressure to make them flat; will most likely have hills and dips in top when clamps are removed.
BTDTGTTS

+1 With flat boards to start, you don t really need clamping cauls. Like others posted before, I alternate my clamps top/bottom and only occasionally need to use spring clamps to keep outer ends aligned on flat boards.

Best Luck.

- CaptainKlutz

The boards look flat when sighting them and feel flat to the touch. But when I stack two pieces on their faces, there are some small gaps, so I know they are not perfectly flat. However, they are as flat as I’m able to get them with the equipment and experience I have. I don’t have dead-flat surface large enough to lay them all out side by side and fairly see how flat they lay next to each other. I don’t expect the cauls will have to overpower twisting and cupping, that was taken out while preparing the boards. Just keep them in line with each other, especially as they tend to slip around with glue, etc.

-- The plan is wrong; my finished piece is right.

View LeeRoyMan's profile

LeeRoyMan

1261 posts in 537 days


#11 posted 06-24-2020 03:48 PM

How wide are your pieces and are you going to clamp them all at once?
It’s easier to do 2 halves, then clamp the halves together.

4 Cauls should be plenty.
About 4” in from the edge, and a couple evenly spaced in the field.

Snug the cauls just enough to hold the planks flush with each other, (shouldn’t have to bear down on them),
Then put on your clamps. I like to snug the clamps tight, then after about 10 to 15 minutes I go around and give them another crank. It’s just what I do.

-- I only know what I know, nothing less, nothing more -- That doesn't count what I used to know..

View bandit571's profile

bandit571

26199 posts in 3493 days


#12 posted 06-24-2020 03:59 PM

What I had to do for this top made out of 1/4 sawn White Ash…..along with rub joints as I built the panel….end cauls outboard of the clamps. Middle caul is centered in the panel

-- A Planer? I'M the planer, this is what I use

View Travis's profile

Travis

465 posts in 576 days


#13 posted 06-24-2020 04:42 PM


How wide are your pieces and are you going to clamp them all at once?
It s easier to do 2 halves, then clamp the halves together.

4 Cauls should be plenty.
About 4” in from the edge, and a couple evenly spaced in the field.

Snug the cauls just enough to hold the planks flush with each other, (shouldn t have to bear down on them),
Then put on your clamps. I like to snug the clamps tight, then after about 10 to 15 minutes I go around and give them another crank. It s just what I do.

- LeeRoyMan

Thank you!
My pieces are variable width, I think there are 6 pieces total, final width will be 40”. Range is between 5-11” wide. I was planning on doing it all in one glue-up, with the assistance of the cauls. But maybe I should do it in 2.

-- The plan is wrong; my finished piece is right.

View Travis's profile

Travis

465 posts in 576 days


#14 posted 06-24-2020 04:43 PM



What I had to do for this top made out of 1/4 sawn White Ash…..along with rub joints as I built the panel….end cauls outboard of the clamps. Middle caul is centered in the panel

- bandit571

What size was that panel bandit?
Way to use those F-clamps!

-- The plan is wrong; my finished piece is right.

View HokieKen's profile

HokieKen

14577 posts in 1948 days


#15 posted 06-24-2020 05:16 PM

If you have 6 pieces, I would glue up 3 and 3 then glue them together. Actually, if it were me, I’d do 2+2+2 then glue two of those together then the final glue up. In other words, unless absolutely necessary, I don’t like to glue more than two pieces together at a time. If you’re doing all 6 at once though, I would absolutely use cauls. Probably no more than 18” or so apart.

-- Kenny, SW VA, Go Hokies!!!

showing 1 through 15 of 40 replies

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics

HomeRefurbers.com