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  #1   Report Post  
GonnyGump
 
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Default Lag bolts vs. carriage bolts

Bottom line: Which is stronger, lag bolts or carriage bolts?

Context and details:
I am building a large (12' long) oak dining room table, the base for
which will be two 18" diameter circular columns. Each of the columns
will sit on a 20" circular "plate" (about 4" thick) that, in turn,
will be supported by four scroll feet. The scroll feet will be
cantilevered out from the plate by about 6". My question is how best
to secure feet to the plate. The two options a a) 4-1/2" lag
bolts up through the heels of the feet and into the plate; or b)
carriage bolts following the same path through the feet and plate and
secured with a nut countersunk into the top of the plate. Can anyone
advise me which will be more secure, both structurally and against any
potential wood movement?

Thanks in advance for useful insights and comments.

jdc
  #2   Report Post  
Dan Parrell
 
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Default Lag bolts vs. carriage bolts

The carriage bolt would be the wisest choice IMO used with a countersuck nut
and washer to prevent the nut from sinking into the wood.You can apply more
torque,get it tighter without the risk of stripping.The lag bolts could
possibly loosen up from side movement or cause a split.
"GonnyGump" wrote in message
om...
Bottom line: Which is stronger, lag bolts or carriage bolts?

Context and details:
I am building a large (12' long) oak dining room table, the base for
which will be two 18" diameter circular columns. Each of the columns
will sit on a 20" circular "plate" (about 4" thick) that, in turn,
will be supported by four scroll feet. The scroll feet will be
cantilevered out from the plate by about 6". My question is how best
to secure feet to the plate. The two options a a) 4-1/2" lag
bolts up through the heels of the feet and into the plate; or b)
carriage bolts following the same path through the feet and plate and
secured with a nut countersunk into the top of the plate. Can anyone
advise me which will be more secure, both structurally and against any
potential wood movement?

Thanks in advance for useful insights and comments.

jdc



  #4   Report Post  
GBsCards
 
Posts: n/a
Default Lag bolts vs. carriage bolts

Is it just me?? I thought (and I could be VERY wrong) lags were screws,
although they could be very big screws. So what the general public refers to
as lag bolts are actually lag screws. Either way, I thing the screws would be
better. Bore the same diameter hole through the legs and a smaller diameter
through the columns to draw it up real tight. Just beware of overtightening.
  #5   Report Post  
RB
 
Posts: n/a
Default Lag bolts vs. carriage bolts

Since you have a 20" dia plate I'd be tempted to put a "real" load
bearing surface in the center of the plate (assuming that it won't be
visible) and regard the scroll feet as only semi functional feet. In
this case they could be fastened to blind nuts, perhaps hanger bolts in
the feet connecting to threaded inserts in the bottom of the 20" dia plate.

RB

GonnyGump wrote:
Bottom line: Which is stronger, lag bolts or carriage bolts?

Context and details:
I am building a large (12' long) oak dining room table, the base for
which will be two 18" diameter circular columns. Each of the columns
will sit on a 20" circular "plate" (about 4" thick) that, in turn,
will be supported by four scroll feet. The scroll feet will be
cantilevered out from the plate by about 6". My question is how best
to secure feet to the plate. The two options a a) 4-1/2" lag
bolts up through the heels of the feet and into the plate; or b)
carriage bolts following the same path through the feet and plate and
secured with a nut countersunk into the top of the plate. Can anyone
advise me which will be more secure, both structurally and against any
potential wood movement?

Thanks in advance for useful insights and comments.

jdc




  #6   Report Post  
CW
 
Posts: n/a
Default Lag bolts vs. carriage bolts

Yes, they are screws. Carriage bolts would be better. Better grip.

"GBsCards" wrote in message
...
Is it just me?? I thought (and I could be VERY wrong) lags were screws,
although they could be very big screws. So what the general public refers

to
as lag bolts are actually lag screws. Either way, I thing the screws

would be
better. Bore the same diameter hole through the legs and a smaller

diameter
through the columns to draw it up real tight. Just beware of

overtightening.


  #8   Report Post  
GonnyGump
 
Posts: n/a
Default Lag bolts vs. carriage bolts

Thanks to all for the feedback. Love the web... acquired most of the
knowledge I most value about woodworking right here! Here are some
responses.

Lag bolts are indeed screws, as others have noted. Sorry... I
supposed I was primed by the misnomer posted over the bin at which I
bought these at the local home improvement warehouse.

Considerations of assembly-disassembly have entered my mind. While I
agree in principle that the c-bolts are better in this regard, they
would be less convenient for my particular configuration: The column
will overide the countersunk nuts in the plate, so to get to them (to
tighten or diassemble the feet) I would have to remove the columns.
Not so for the lags.


wrote in message . ..
On 7 Apr 2004 17:28:10 -0700,
(GonnyGump) wrote:
can you make the feet from continuous members? that is, opposing pairs
of scrolls cut on the ends of a 32" long board. half lap where they
cross, run a fastener through there into a cross brace in the column.
the load there would be so low it wouldn't matter what you use. it
would just have to be enough to carry the feet along if you picked the
table *up*


Now THAT would have been a good design. Wish I can say I had thought
about this in advance, but didn't. Nevertheless, I'm not sure it
would have worked, given additional details not mentioned (the
specific shape of the feet, constrains introduced by veneering, etc.).
However, most appreciative of the suggestion, which I hope will
inform future exploits!
  #9   Report Post  
Darwin
 
Posts: n/a
Default Lag bolts vs. carriage bolts

How about using threaded brass inserts into the base, then bolt
through the feet?

"GonnyGump" wrote in message
om...
Bottom line: Which is stronger, lag bolts or carriage bolts?

Context and details:
I am building a large (12' long) oak dining room table, the base for
which will be two 18" diameter circular columns. Each of the

columns
will sit on a 20" circular "plate" (about 4" thick) that, in turn,
will be supported by four scroll feet. The scroll feet will be
cantilevered out from the plate by about 6". My question is how

best
to secure feet to the plate. The two options a a) 4-1/2" lag
bolts up through the heels of the feet and into the plate; or b)
carriage bolts following the same path through the feet and plate

and
secured with a nut countersunk into the top of the plate. Can

anyone
advise me which will be more secure, both structurally and against

any
potential wood movement?

Thanks in advance for useful insights and comments.

jdc



  #11   Report Post  
GonnyGump
 
Posts: n/a
Default Lag bolts vs. carriage bolts

"Darwin" wrote in message ...
How about using threaded brass inserts into the base, then bolt
through the feet?


Since such inserts are usually much shorter than the lag screws that
can be used, I would guess that they would be less secure than the
lags.

jdc
  #12   Report Post  
Darwin
 
Posts: n/a
Default Lag bolts vs. carriage bolts

You're right that they would be much shorter.



With that said tho -- they would be inserted into your base, into the
face grain. I've had really good luck with them; sometimes they can
be a PITA to install. Plan their placement; with out looking at your
design; I would say a couple in each foot would be needed to keep them
from torquing.



FWIW you'll want to make sure you get the "right" ones, some have very
coarse threads like a lag bolt except sharper, others have a more fine
thread, similar to a course stove bolt, but sharper. I like the ones
with the course threads, I found them easier to install, and don't
crush the wood quite as easily. Others may have their preferences.



Good luck...





"GonnyGump" wrote in message
om...
"Darwin" wrote in message

...
How about using threaded brass inserts into the base, then bolt
through the feet?


Since such inserts are usually much shorter than the lag screws that
can be used, I would guess that they would be less secure than the
lags.

jdc



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