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Holtzapffel laminating blues

1599 Views 8 Replies 6 Participants Last post by  a1Jim
I'm new to woodworking, so if this question's already been covered before just let me know; otherwise, any help would be appreciated. Maybe some of you on the board have some tips on what I can do to improve my glues-ups.

I've been building a Holtzapffel workbench after being inspired by Christopher Schwarz's Holtzapffel, and this week I'm in the process of laminating the top of the bench, but it seems no matter how much I joint/plane I still end up with hairline gaps in some of the laminations. It's been very frustrating.

Here's some of the details of my process:

After preparing the stock on a power jointer and planer, I try to fine tune the sticks as best I can with a jack plane and jointer plane.

At this point I dry fit the boards and usually there's very few to no gaps. I'm using 8 Bessey 24" clamps staggered along the 6 foot length of 3 1 3/4" maple sticks to clamp up these subassemblies. I've been using the Titebond III glue, and I apply the glue to both surfaces and roll it on with a sponge roller prior to glue-up. I've been allowing at least 5 hours. Also, there's plenty of squeeze out on both sides.

After removing the clamps and cleaning the assemblies up on the jointer, I have hairline cracks that have been very disappointing - maybe I'm expecting too much, but it seems by looking at other people's work I can do better. I'm attaching a link to show you what I mean. These are 2 assemblies after cleaning up on the jointer:
Any suggestions on what I can do to improve?
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I don't know much about jointing.

Your photo link says: This photo is private. Oops! You don't have permission to view this photo.
Hey, sorry about that - it's fixed now.
The only thing I can think of is that when you prepared the edges to join, the edges were uneven across the grain. So, when first joined the edges came together and looked tight but after you took some of the wood off afterwards it revealed an uneven area, a sort of internal gap caused by uneven joining. Does that make any sense?
Jointing those long boards on a 6" jointer is impossible so like COTL said you are most likely revealing internal gaps when you joint it after glue up. Take a peep at my blog to see how I finally figured out how to joint those long boards (tablesaw & monster straight edge).
are the besseys you use parallel clamps? or F-clamps? are you using cauls to even out the pressure of the clamps across the entire board lengthwise and height wise? are the gaps existing where there was no clamp? or also where you had clamps directly over it?

it could be that the boards were not perfectly straight -in which case a monster straight edge as Damian suggested is the way to go. But it also could be internal stresses in the lumber, and once pressure is applied with clamps- areas that are not receiving proper pressure want to back off and gaps are created - in which case - cauls would be the answer (they are a good idea either way)

EDIT: PS. looking at the picture again - it's either too far to see - but I don't see anything alarming… after a little smoothing of the top - some gaps will disappear. some 'gaps' are not actual gaps, but are height differences between 2 laminated boards - once planed down - they will go away.
Thanks for the feedback guys - I think as I respond I'll figure out what's going wrong:

Craftsman, I did take my jack and run it down the middle of the boards based on some advice from a video on the internet i've seen recently, in an attempt to create a shallow "cup" width wise. I might have only created the exact problem you described. It was in the back of my mind while doing it, but I took my chances. It's possible a couple of these sliver gaps are due to that.

Damian, thanks for the reply. I'm using a 6" Ridgid jointer with out feed supports. When I joint the edges, I set my cut to just under 1/16" so as not to take off too much and hopefully get a truer cut, but the boards are never perfect. I usually yattempt to "fine tune" them with my hand planes afterwards and it's kind of hit and miss. I'll take a look at your blog to see what you've got.

PurpLev - I'm using the parallel 24" clamps. I think one of the biggest beginner mistakes I made was starting at the lumber yard while selecting the lumber. I chose most of my 8/4 boards which ended up being 6 1/2" to 7" rough - this for me was really cutting it close when I needed get final 3" thick boards out of them. To make this story short, I only 3 faced them - I left 1 edge rough because I was worried that by after jointing it I'd have it right at 3" and after the final glue up and planing I'd be quite a bit under 3".

This prevented me from being able to use cauls properly so the alignments weren't perfect as I glued them up. In hindsight, I had to re-joint and plane after the sections were glued up anyway, so I should have just made things 4 square and not worried about the thickness.

No, the gaps aren't that bad - just irritating. Most of them are a "hairs" width, but I've seen a lot of tops made from home depot douglas fir, to $$$ hard maple, and they all seem pretty gap free. Maybe after I assemble them into the final top and then start planing it true some of that will disappear.
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I meant cauls to even the pressure your current clamp setup is creating - not to level/align the boards flush. sometimes there are points between the clamps that don't get adequate clamping pressure, and might result in some gaps.

you'll be surprised how many of those seemingly 'gaps' will completely disappear after you flatten the top.

good luck - looks like you're getting there !
Forest I would check the square on your jointer. I'm guessing it's off just a little.
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