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biscuit strengh

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Forum topic by mission76 posted 08-15-2008 09:35 AM 1122 views 0 times favorited 8 replies Add to Favorites Watch
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mission76

47 posts in 3524 days


08-15-2008 09:35 AM

Trying to make a “step back bookcase” that is in a book I bought that had the design, cut list, and guide for making it. I decided to make it like he did, with no deviations. My only problem is he uses biscuits to create the lower case cabinet, and only three biscuit slots per side. I cut the slots and it just doesn’t seem like biscuits will hold this thing together when it is finally assembled, and weight is added. I normally used biscuits to join boards or attach face frames, and I use rabbits and dados for case construction. Will three biscuits per side of a 28”l x 38”w x 22”d hold up in the long run? I see it’s a popular choice for cabinet construction but is there any rule as to how many biscuits to use?

Anyway here is a picture of the bookcase, hopefully someone has made it already and can tell me what they did
http://www.jdwoodworking.com/gallery/23bookcase_wdesk.htm


8 replies so far

View Catspaw's profile

Catspaw

236 posts in 3717 days


#1 posted 08-15-2008 01:04 PM

Every one keeps saying how glue is stronger than wood. If this is true then biscuits are only there to align the wood (assuming there is no other set alignment such as rabbets or dadoes) during glue up. The biscuits would, therefore, be superfluous. If this is not true, then the joint is no stronger than the wood beyond the glue and biscuits anyway.

Then again it takes less time to throw another biscuit or two into the mix than it does to worry about it.

I biscuit at about 10” intervals or so.

-- arborial reconfiguration specialist

View CharlieM1958's profile

CharlieM1958

16272 posts in 4120 days


#2 posted 08-15-2008 03:01 PM

I agree with Catspaw. If more biscuits make you feel better, go for it, but I don’t think they are necessary.

-- Charlie M. "Woodworking - patience = firewood"

View Chiefk's profile

Chiefk

163 posts in 3672 days


#3 posted 08-15-2008 03:16 PM

Mission76, Just because the plans call for using biscuits doesn’t preclude you from constructing the cabinet another way. If you normally use dados and rabbits in your construction then I don’t see why you couldn’t in this project. Just my 2 cents. pkennedy

-- P Kennedy Crossville, TN

View teenagewoodworker's profile

teenagewoodworker

2727 posts in 3669 days


#4 posted 08-15-2008 03:45 PM

biscuits really don’t add any considerable strength. you should be much better off going with a dado or better yet a sliding dovetail. like said above the glue is harder than the wood so the real strength comes in the wood joints. dado’s, dovetails, mortise and tenons, and the like. biscuits would not help you in a bookcase situation because if you are using solid wood you would have a long grain on end grain and that is a really weak glue joint. so the glue wouldn’t be helping much. you really want a dado or a sliding dovetail because it gives the wood strength. the glue helps but when you thing about it most of the contact is still end grain to long grain. so the strength comes in the joint and the glue really holds it all together.

View Roper's profile

Roper

1384 posts in 3614 days


#5 posted 08-15-2008 03:59 PM

you could use a festool domino instead of biscuts, they are much stronger and just as easy.

-- Roper - Master of sawdust- www.roperwoodturning.com

View Joey's profile

Joey

276 posts in 3717 days


#6 posted 08-15-2008 06:41 PM

the only problem with buying a festool is it’s about $600 more than a biscuit joiner.
I wouldn’t depend on biscuits to add any strength, i’ve only used them for alignment only.

-- Joey, Magee, Ms http://woodnwaresms.com

View Roper's profile

Roper

1384 posts in 3614 days


#7 posted 08-15-2008 09:31 PM

and worth every penny.

-- Roper - Master of sawdust- www.roperwoodturning.com

View mission76's profile

mission76

47 posts in 3524 days


#8 posted 08-17-2008 01:16 AM

thanks for the help, the reason why I was using biscuits was because I just wanted to try out some other methods for case construction other than my usual dado and rabbets. I went ahead and finished the biscuits today and while it worked and seems to be fine, I will probably never do it again. Rabbets and dados are so much easier then this method.

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