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View jcyphert's profile

Why did this Crack!!!

by jcyphert
posted 02-05-2018 02:35 PM


22 replies so far

View Aj2's profile

Aj2

2558 posts in 2356 days


#1 posted 02-05-2018 02:43 PM

Absolutely it was the plywood.

-- Aj

View jcyphert's profile

jcyphert

34 posts in 1430 days


#2 posted 02-05-2018 02:45 PM

Suggestions on fixing it? 3/4” deep relief cuts on the bottom?

View bbasiaga's profile

bbasiaga

1243 posts in 2553 days


#3 posted 02-05-2018 02:46 PM

As it tired to expand and contract with temperature and humidity, it could not due to being fastened to the plywood. Stress built and it cracked.

Brian

-- Part of engineering is to know when to put your calculator down and pick up your tools.

View Lazyman's profile

Lazyman

4166 posts in 1945 days


#4 posted 02-05-2018 03:14 PM

Gluing it to the plywood probably caused it to crack rather than preventing it. The cherry will expand and contract across its width with changes in moisture. The PW will move almost none. The tangential shrinkage factor for cherry is about 7% which (I think) roughly equates to about .0023” movement for each 1% change in the moisture of the wood (if I am doing the math right). So if the wood was at say 15% moisture content when it was glued to the PW and when you brought inside and you turned on the heating and/or AC on it dropped to 12%, it wants shrink a little more than 1/16th of an inch for each 1 foot of width (there is very little movement in the length). So if you glue the cherry to an immovable surface, either the glue has to fail, which is unlikely if you glued and screwed it down well, or the wood has to split or buckle (depending upon which direction the moisture moves) to relieve the stress.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

View bonesbr549's profile

bonesbr549

1584 posts in 3625 days


#5 posted 02-05-2018 08:13 PM

Lazymand hit the nail on the head. You bound it to a material that would not move so it could not move and shrank and cracked.

As to the fix, tough you could remove screws and try to get that ply off and redo, by attaching to the bar with a non binding method i.e. crazy-eights or just chuck it to experience and redo the top.

Sometimes experience is painful. I had to redo a series of cabinet doors due to learning what happens when glue seeps into the grove of the rails and styles and you put the raised panels in. They cracked. I fiddled with a bunch of options to “save” and ended up chucking and doing over.

-- Sooner or later Liberals run out of other people's money.

View jcyphert's profile

jcyphert

34 posts in 1430 days


#6 posted 02-05-2018 08:25 PM

Thanks for the help. I’m going to give the relief cuts on the plywood back a try first. One every 6 inches or so. I’m hoping that will give it enough room. Otherwise, it will be a re-do. Hope I can at least save the bar rail…. I think it was just screwed on.

View Smitty_Cabinetshop's profile

Smitty_Cabinetshop

16253 posts in 3176 days


#7 posted 02-05-2018 08:25 PM

Ditto to Nathan and Bones, they’re right on the money. You simply cannot keep solid wood from moving by glueing/screwing to plywood. Wood’s gotta move, and that movement must be accommodated in some way.

-- Don't anthropomorphize your handplanes. They hate it when you do that. -- OldTools Archive --

View jcyphert's profile

jcyphert

34 posts in 1430 days


#8 posted 02-05-2018 09:12 PM

Any takers on thinking the cuts thru the plywood will work? After hearing from everyone, I certainly don’t know what I was thinking using the solid play base… It seemed like a good idea without thought applied.

View Smitty_Cabinetshop's profile

Smitty_Cabinetshop

16253 posts in 3176 days


#9 posted 02-05-2018 09:29 PM

Try to free it from the plywood altogether, and then glue the cherry back together and ‘mount’ the cherry to the ply using elongated holes in the ply. That way the cherry can move. Short of that, cutting through the plywood will get you to the point the piece can be glued, but it will happen again more likely than not. Next time it may be a buckle rather than a crack.

-- Don't anthropomorphize your handplanes. They hate it when you do that. -- OldTools Archive --

View Woodknack's profile

Woodknack

12945 posts in 2938 days


#10 posted 02-05-2018 09:32 PM

Grab a good book on woodworking to learn the basics.

-- Rick M, http://thewoodknack.blogspot.com/

View jcyphert's profile

jcyphert

34 posts in 1430 days


#11 posted 02-05-2018 09:33 PM

Thanks for the backhanded slap Rick… Real Classy


Grab a good book on woodworking to learn the basics.

- Rick_M


View Lazyman's profile

Lazyman

4166 posts in 1945 days


#12 posted 02-05-2018 09:37 PM

In theory, the relief cuts could relieve the stress and prevent more cracking. I’ve never tried that but if someone brought this to me and asked me to fix it, that is what I would try. Note that if you also glued the panels to the frame you could be in for problems where the panels’ grain is at right angles to the grain in the frames.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

View jcyphert's profile

jcyphert

34 posts in 1430 days


#13 posted 02-05-2018 10:52 PM

The panels are not glued. Thanks for your input!

View fivecodys's profile

fivecodys

1530 posts in 2194 days


#14 posted 02-05-2018 11:46 PM



Any takers on thinking the cuts thru the plywood will work? After hearing from everyone, I certainly don t know what I was thinking using the solid play base… It seemed like a good idea without thought applied.

- jcyphert

We all make mistakes and hopefully we learn from them. I sure have had my share! :)
At this point I would try the cuts through the plywood.

Good luck!

-- When you leave your shop for the night, make sure you can always count to 10.

View JBrow's profile

JBrow

1368 posts in 1478 days


#15 posted 02-06-2018 01:24 AM

jcyphert,

The relief cuts that extend all the way or nearly all the through the thickness of plywood underlayment would be my repair approach. Making a relief cut every 6” may be enough, but I would probably make relief cuts 2” to 3” apart since I would like to make sure I never had to revisit this repair. The relief cuts could be made using a table saw, circular saw, or a router with a straight bit.

Eliminating the plywood backer would be more effort but should also prevent reoccurrence of splits. If this option is selected, a handheld router with a straight bit or a bottom cleaning bit in multiple light passes may be the easiest method and would reduce chances of damaging the bar top.

If you can manage a relief cut under the crack, it may be possible to spread some glue into the crack and draw the bar top back together.

View jcyphert's profile

jcyphert

34 posts in 1430 days


#16 posted 02-06-2018 01:29 AM

JBrow,
My thoughts (hopes) exactly. I’ll let everyone know when I find works (or didn’t).

Thanks again everyone.

View bonesbr549's profile

bonesbr549

1584 posts in 3625 days


#17 posted 02-06-2018 01:36 AM

man, just bite it and do over. By the time you try to figgure away around you could have just redone it. Save the rail and redo the top…

-- Sooner or later Liberals run out of other people's money.

View Woodknack's profile

Woodknack

12945 posts in 2938 days


#18 posted 02-06-2018 01:50 AM

Thanks for the backhanded slap Rick… Real Classy
- jcyphert

I was being sincere. We all learn. A good book on woodworking will help you get the fundamentals so you can skip these kind of mistakes and make things that will not crack or come apart a few years later. The reason I recommend a book, is because books take a lot more effort to get published than internet sources, the authors are generally very experienced, and the information is more reliable.

-- Rick M, http://thewoodknack.blogspot.com/

View TheFridge's profile

TheFridge

10859 posts in 2044 days


#19 posted 02-06-2018 02:04 AM

Burn

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

View AlaskaGuy's profile

AlaskaGuy

5419 posts in 2867 days


#20 posted 02-06-2018 02:51 AM

Having made plenty of mistakes myself and without seeing how the whole bar is put together I’m with bonesbr549 and TheFridge.

Often times it takes longer and comes less quality than the original after a ton of work. I’d give serious consideration of starting over with the top.

-- Alaskan's for Global warming!

View TheFridge's profile

TheFridge

10859 posts in 2044 days


#21 posted 02-06-2018 03:02 AM

Ditto. Or a slight redesign.

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

View woodbutcherbynight's profile

woodbutcherbynight

5974 posts in 2967 days


#22 posted 02-06-2018 06:09 AM



... It seemed like a good idea without thought applied.

- jcyphert

It is a learning process. Mistakes happen. Look at it on the bright side, nobody was injured, you have all your digits. Sure you have to go back and fix it. And yeah you will take some beating for it.

That said let me share a few times I have said same thing. Enjoy the laugh.

Lets see some of my better moments:

Ignored the incoming alarm and kept working, yes they blew something up close to us. You don’t want to know what my buddy said…. But it seemed like a good idea at the time.

Stood on top of a bunker smoking, screaming bring it I can do this all night, at the top of my lungs, for over an hour at the enemy as they tried to make way across the berm,. Did I mention a band from the USO was inside the bunker? Yeah, 1st performance and look what they get, the raving lunatic on top of the bunker. It seemed like a good idea at the time.

Sent this picture back to my Mother, It seemed like a good idea at the time. My Father loves this picture, my Mother shoots him with molten beams of death in his chair if he brings it up.

-- Live to tell the stories, they sound better that way.

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