DIY: Converting antique bed to queen mattress

Original full size antique bed

It was the week before the Indy 500 Race, and we had two couples coming for the weekend.
One of our guest rooms was well-equipped with a queen size bed, but the second guest room had a full size bed(that previous guests complained about).

Granted the second guest room was filled with a beautiful antique bed and matching dressers over 100 years old, but that was part of the dilemma. Do we replace the mattress with another full size mattress, or could we somehow fit a queen size mattress?


When I initially approached Mike about the idea of a queen size mattress, he didn't want to remove the antique furniture in the room.  But a funny thing happened overnight.  Mike woke up with an idea for converting the full size antique bed into a queen size antique bed.  And his idea was to preserve the original antique bed without damage, in case the Antiques Road Show ever came to town.

Of course as these things happen, we had only 3 days to find and buy a mattress, convert the antique bed, have the mattress delivered and be ready for guests on Thursday evening.

Were we up for the challenge, or just plain crazy?  Yes and yes.


Mike did all the work on this project, and I asked him to describe his steps.  

1.  Measured headboard and foot board width and checked queen mattress dimensions on Google.  Determined that headboard and foot board were just slightly smaller than width of a queen mattress.  Decided we could make this work.

2.  Removed full size mattress and box spring set to gain access to the embedded bolts of the antique wooden side rails.  Removed the side rails from bed with quarter-turn repetitive turns.

3.  Checked the size of the embedded captive nuts in headboard and foot board by inserting 3/8" and 5/16" bolts.  These did not fit and were not a common thread.

4.  Used a long magnet stick and ice pick to extract the non-standard captive nuts from the square leg sections of the foot board and headboard.

Removable metal tab

5.  Since it had been so difficult to remove the embedded captive nuts(with magnet and ice pick), I decided to create steel tabs that could be used to easily remove the new nuts.  I also decided to use 5/16" tee-nuts.  To create the steel tabs,  I  cut 4 pieces of steel, ¾” wide and 1/8” thick.  I then drilled holes for the 5/16” tee-nuts, and I silver-soldered the nuts into the steel stock and cut them flush with the stock.  So now I have a common size nut(5/16") and a removable tab.

Queen size metal frame

6.  We purchased a queen metal frame designed for use with a modern brass bed.  This had brackets on each end designed to attach to a headboard and foot board.

Paper template tracings

7. Next step was to create wooden adapters as an interface between the metal bed frame and headboard and foot board. This was necessary so we didn't damage the antique.  I created a paper template of the holes by affixing a piece of paper over the headboard and foot board holes and used a lead pencil to lightly rub and create an outline of the holes that match the dowel pin locations and also the access hole to the  captive nut.

8. Using the paper templates, I created four oak transition pieces.  I drilled 1/2" dowel pin holes and 5/16" holes for the bolts(which matched the 5/16" diameter bolts in the new bed frame.

 9.  I used the largest bolts possible for maximum strength.

Mike affixing the oak adapter pieces

10.  After drilling these four oak adapters, I mixed various wood stains to get the right  color to match the antique.  I stained those surfaces that would be seen outside the bed frame.

11.  The dowel pins were installed to where they protruded slightly from the oak adapter pieces so that I could align them to the headboard and foot board.  At this point I  tapped them in with a small hammer and inserted the 5/16” bolts through the  captive nut assemblies on each corner to tightly secure them to the antique headboard and foot board.

Bolts and dowels in place

View from outside the bed

12.  With the wooden adapters secured,  we stayed consistent with the original bed frame height and to be able to store stuff under the bed.   I raised each corner of the bed frame  and used  5/16” carriage bolts, washers, and nuts through the slots of the metal  bed frame to secure it firmly to the headboard and foot board.

New dowel legs for additional support

13.  I decided to use a 2" diameter hardwood dowel (stained to match the wooden adapters) to create 5 supports for the correct height of the metal bed frame.  I drilled the top of each of the 5 supports with a 1” Forstner bit to slip over the five vertical tubular steel  foot  supports(already on the metal bed frame). I drilled the bottom with a 3/8" hole to fit the adjustment screw on the metal frame.

14. I hammered furniture t-nuts into the bottom of each of these dowel sections, and threaded the feet into them.   I slid these wooden leg extensions onto the  bed frame and used aluminum shim stock to take up the slack between the vertical tubular steel and the 1”  diameter holes.

Queen mattress in place

Finished product

The project was finished ahead of schedule, and our guests enjoyed the new bed during the Indy 500 race weekend!

Mike did a fantastic job completing this project, effectively compromising between his desire to keep the antique bed intact, and my desire for a queen size bed.  I am now convinced he can do anything...

Diane