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Forcing end grain strips flat with cauls ?

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Forum topic by lennyk posted 11-01-2016 01:09 AM 424 views 0 times favorited 5 replies Add to Favorites Watch
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lennyk

32 posts in 670 days


11-01-2016 01:09 AM

I live in the tropics, extreme humidity. Made several end grain boards last year for the first time and more again this year. Been using purpleheart and bulletwood. Wood is dry and pretty old too.

Today I did the final cutting of strips for an end grain cutting board glue up.
Crosscut them and the all were nice and flat, gave them a minute shave on the jointer and light sand so the side to sides would be nice and tight.

Took the pieces home to glue up and as usual there was some bowing due to the humidity so the strips are uneven. Have tried all manner of checking whilst clamping etc to get perfect alignment but never works out.

As usual I have a lot of sanding to do which I really hate as the belt sander has to be used first but it heats up the wood so have to take frequent breaks=time. Sanding end grain purpleheart is quite task.

Would forcing the strips flat with cauls be dangerous to cause splitting ?
It is really a pain to have perfectly lined up strip boards, all flat for the final cut they go out of whack after the final crosscut.

The humidy here is so bad, I once put some boards flat on a table after final sanding pre oiling
the next day they were seriously cupped, like 1/4” up on the sides. I have to store unoiled boards vertically to be safe.

I am so pissed as usual I am tempted to try putting them through my 735 planer.

What are typical variances experts expect to have to sand down ?


5 replies so far

View Aj2's profile

Aj2

1178 posts in 1637 days


#1 posted 11-01-2016 01:19 AM

Lenny that’s a bummer,Don’t put them thru your planer,End grain Purple Heart is nasty hard.
I don’t know if forcing them flat for your glue up will cause problems but I do think it’s a bad habit if it works.
I would look at what you can do differently for your next one.
One thought I have is to make a thicker board.
My end grain boards are 13×13x 2 inch + thick.
My experience has been the thicker the better.
Good luck

Aj

-- Aj

View CopperTree's profile

CopperTree

53 posts in 897 days


#2 posted 11-06-2016 06:07 AM

I agree, thicker is better for stability. Another trick is to plan for some misalignment during the second glue up and size the strips accordingly. I always send my end grain boards through the thickness planer with a sacrificial strip glued on each end, then through the drum sander. Light passes are necessary but the sacrificial strips prevent any tear out. I then use those strips as hold down points on the CNC router when cutting the juice groove and the profile cut.

Here is a blank after planing and sanding:

And here is the finished board:

View lennyk's profile

lennyk

32 posts in 670 days


#3 posted 11-06-2016 10:24 AM

nice,
the good news is I used a 100grit on my belt sander and was able to sand very quickly
I previously only used to use my belt sander for rough material with 60 or 80 belts
what I have discovered is those grits may be coarse but the grains arent sharp so would take forever one
hardwood end grain. The 100 flattened in no time at all.

View UncannyValleyWoods's profile

UncannyValleyWoods

542 posts in 1703 days


#4 posted 11-06-2016 12:04 PM

What are you using to clamp them? Pipe clamps?

One piece of advice I would give you is this; do not sand or joint the crosscut pieces before you glue them up. I get the impulse, but it’s always going to cause problems if you do this. If your crosscut pieces aren’t coming out clean enough, then you need to sharpen or replace your blade or build a better crosscut sled to cut them with. Even if there are burs on the edges of my crosscut pieces, I never sand them off or buff them down. I simply take them straight to my pipe clamps, apply a copious amount of tight bond 3 and clamp them up.

When in my pip clamps, I am sure to clamp them both on the top and the bottom and I leave them clamped for 24+ hours.

-- “If Jesus had been killed twenty years ago, Catholic school children would be wearing little electric chairs around their necks instead of crosses.” ― Lenny Bruce

View splintergroup's profile

splintergroup

1702 posts in 1061 days


#5 posted 11-06-2016 03:08 PM

I always us a boat load of tall cauls when gluing up strips, like with cutting boards. They do the job!

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