Highboy question

R

rchampagne

Well-known member
Since we are looking for some discussion, thought I'd throw this question out there.  I am building a Newport bonnet top highboy, based on plans I got from Al Breed.  Since Al has built the piece already I've been sending most of my questions to him.  I'll send this one out the to group in general in the hopes of boosting the action on the forum, and also to give Al a break (he has been very generous with his information, which I greatly appreciate). 

Anyway, after all that, my question is what are people's experience with putting the "roof" on the bonnet top?  The material has to be pretty thin, about an 1/8", to make the required bends.  I'm not quite there yet in the construction, but am looking forward to giving this a try for the first time.  Do you steam it?  I've read about people using tape on the underside to minimize cracking.  What do you do?
Thanks,
Rob
 
Rob, I have used 1/8" baltic birch plywood; not exactly the 18th century way! It bends enough without any problems, and is up out of the way so as not to attract too much attention, criticism, and disdain!  I firmly believe the 18th cent. guys would have used something similar had they had it.
What do Al Breed's plans call for? John McAlister
 
Rob,

I would stave mine like a barrel, i.e., I cut strips 5/16-3/8" thick by 1-1?" wide.  Then angle the edges so they butt up to each other then glue and nail the ends.  I would also add a brad in the center of the long edge to act as a dowel pin so when the adjacent strip is butted up it will now be locked in place.  This also helps to keep it from bowing.  Then smooth with a plane.  I'm sure this is not historically acurate but the roof will not crack and split as compared to using a solid piece.  I think the old ones were made using green riven wood.

Some people will glue a piece of canvas to the underside of a thin board (roof) to help keep it from splitting.  I've never tried this.  Has anyone?

Dennis Bork
Antiquity Period Designs, Ltd.
 
Thanks John and Dennis.  John, the drawings I got from Al are the measurements he took from an actual piece.  They aren't a full set of plans and don't include anything like a cut list, etc, just the salient full size parts & carvings.  I think he indicates an 1/8" rabbet for the roof behind the pediment molding.  I was assuming the roof would be 1/8" solid pine. 
Rob
 
Rob,

I once tried to bend 1/8" material for the roof. It kept splitting and was very difficult to bend.  I did not soak or steam it.  Let us know what Al says.

Dennis Bork
 
Rob, I built a bonnet top highboy with the "roof" made out of solid poplar. I resawed it on the band saw then ran it through my thickness  planer. I used pieces about ten inches wide, they were planed to about 1/8-3/16. I had a rabbet cut into the moulding at the front side and it sat on top of the blocking at the back.  I had the poplar pretty wet when I installed it predrilling and nailing and gluing it into the moulding and the block. I did not use anything as a backer. I used two pieces to cover the area needed. I think that one piece cracked when I tried the install, that when to the fire box and I used the next piece in line. This has been in place several years now and has not cracked in place. Good Luck on whichever method you use and keep us informed on how it works out. Kerry
 
Thanks Kerry, when you say wet, do you mean you submerged it for three days or do you mean you sprayed it with a mister 15 minutes before hand?  I have been using poplar for the secondary wood throughout this piece, so I might go that route instead of pine.  Any opinions on which would bend easier?
 
I have had success (two times; highboy and secretary) with 1/8" poplar edge glued together with artist canvas attached to one side with contact adhesive. Once the contact glue dried, I planed the thickness to about 3/32" and then misted the outer surface with water as I bent and nailed it in place.
 
I've done two bonnet tops.
The first, I made out of clear white pine, resawn shy of 1/8" thickness. I then wet what would be the convex side with a wet towel, the piece quickly bent to shape and I nailed it down on the bonnet. After it dried I stained with an oil based stain to match the wood (cherry). Several years later it is intact.
Recently I tried the same thing with thin mahagony. It was much less forgiving, cracked while being nailed down and after drying.
I'd do the clear pine method on the next one I make.

Haoward Steier
 
Rob, If I remember correctly I soaked a cotton rag (old t shirt) with water and laid it on the wood for maybe 15 mins. I also rubbed the wood down pretty good with the wet rag first. On this piece all of the secondary wood was poplar also with the primary walnut. I did not stain the poplar top after it was installed I left it natural. I used an oil and shellac finish on the walnut, all the secondary had no finish. I try to use period correct techniques when I build not to worry too much about trying to improve on age.
 
Kerry & Howard,

Do you have extreme seasonal temp & humidity changes where you live?  I know here in Wisconsin where I live these changes will most likely cause the roof to crack and split.  Summer can be 80%+rh and winter 25%rh.  Did you glue and nail or just nail down the roof?

Dennis Bork
 
Hello Dennis, I live in the north eastern part of Maryland at the top of the Chesapeake Bay, and yes we do experience bits of extreme humidity during the summer. Not as bad as tidewater VA. but we have our share. I did glue the wood in place and used a couple of nails. I use the a/c in the summer months and radiant heat in the winter. I don't think that the the temps in my house are extreme which would explain the stabilization. When I build I try to stay close to origanal const. details. I have a demilune table that is veneered onto a solid pine substrate that does tend to warp a little in the summer months but always flattens back out in the fall.
 
Dennis,
I live in Virginia Beach. Humid like a swamp in the summer, far enough north to be dry in the winter. But my house probably has fairly constant humidity. I believe thin pine is fairly forgiving as far as changes with moisture. It's been OK for 3 years (not a long time) but so far so good.

Howard Steier
 
I believe the originals were often done with chestnut, about a strong eighth thick, nailed.  Canvas is doubtful, but the underside is not visible unless you take one apart and I haven't.  I do them in poplar with no trouble.  Wetting it down before installing helps.  Predrilling helps, square nails do not.  Some of mine have cracked, but then so have I, and I'm not worried about it.  I did hear one crack one night, quite loudly, in the first winter indoors in a room with a fireplace burning.
I have closeup photos of a John Townsend chest on chest, but the upper case is identical to a highboy in all respects.  I can't post these due to file sizes, and don't know how to compress files.  I also have a measured drawing of this chest on chest which anyone is welcome to, simply for the asking.  Let's hope I'm not deluged, as I've a couple of scans of the drawings, but no means to send anyone hard copies.
Johnny D.
 
Construction details:  tops were done in three pieces, nailed much of the way around, but not to the level crown moulding.  This may have to do with the level crown not being glued its entire length, but this is speculation.  There are two vertically oriented boards which form nailers for the top.  These are attached to the upper carcase by means unknown to me, but I'd bet your life that there are glue blocks in there.  These nailers are beveled with a slight curve on top to the angle of the bonnet and are placed on either side of the pediment opening.  My photos show this well.  The crown moulding is held about 3/16" above the pediment board, forming a rebate into which the top is nailed.  At the rear, the top board extends to the full back of the case and is nailed onto the arched backboard.  The pediment backer appears to be rebated to receive the top.  The originals are ALL split, many showing evidence of repairs or taping.  I have heard, but do not know, that while Goddard's crown mouldings were attached with only limited bearing on the upper carcase, Townsend kept his crown almost entirely on the carcase (the latter is true).  The upper backboard (there are typically three on the upper case) goes below the top of the carcase to give strength, perhaps to the tune of 2 3/4 inches.

JD
 
John,
Thanks for posting.  Where are you located?  I for one would be interested in learning more about the chest on chest. 
Thanks,
Rob
 
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