Construction Plans for the McEmn Mark III Whelping Box

This is our third generation whelping box. Our construction method sandwiches plywood panels between steel tee nuts and steel corner braces which tie everything together. This results in a very strong but lightweight assembly. It was designed to meet the following goals:

This design can be easily adjusted to build a whelping box to fit your space and the space requirements for your breed.  For Great Danes, we have found that five foot square is a good size.  Four foot square is workable, but crowded, especially if you have a litter with a lot of puppies.  We buy fleece in a five foot by 10 foot roll and cut it to length to make two custom fit bottoms.  The source is www.masterpiecepetproducts.com, 806-771-4242.  Tell Sheila that Kent Akselsen and Nikki Riggsbee sent you.

Lumber Required for a 60" (five foot) Square Whelping Box

Quantity

Description

2

4' x 8' sheets of 5/8" plywood for sides and seats.  This design will work with low grade construction plywood, but you can avoid a lot of splintering, wood filler, and sanding by going with a higher grade.  A hardwood or cabinet grade plywood will make a nicer final result.

4

2x4 x 60" lumber. (For pig rails)  Make sure that they are as straight (no twist) and splinter-free as possible.

1

quart polyurethane varnish or other nontoxic paint.

Hardware list from McMaster-Carr Supply Co.    www.mcmaster.com  or  404-346-7000

Quantity McMaster
Part Number

Visual

Description

Price as of Jan 2012

8

1088A33

Steel Three-Sided Corner Brace Zinc-Plated, 4" Length Of Sides, 7/8" Width

$3.55 Each

1

90975A050

Steel Tee Nut Zinc-Plated, 10-24 Internal Thread, 7/16" High Barrel, 3 Prong
You will actually need about 52 Tee Nuts.

$9.78 per Pack of 100

1

92949A244

Stainless Steel Button Head Socket Cap Screw 10-24 Thread, 5/8" Length
You will actually need about 40.

$8.43 per Pack of 100

1

92949A249

Stainless Steel Button Head Socket Cap Screw 10-24 Thread, 1-1/4" Length
You will actually need about 8.  If you can find an equivalent screw at your local hardware store, you might save a few dollars. You may also use these screws as feet and handles when you are varnishing the side panels.

$8.17 per Pack of 50

$54.78 total + shipping

Recommended Tools
Screwdriver with a 1/8" hex drive bit
You need this to put the whelping box together.
Table Saw
You can get by with other types of saws, but handheld saws may make cuts that require a lot of work to smooth adequately.
Drill Press
You can get by with a portable drill, but accurately counterboring the seats and pig rails is more difficult.
1/4" wood bit & 1/2" wood bit.
Using a bit designed to drill wood will give you cleaner holes and less splintering in the plywood.
45/64" to 3/4" spade or forstner bit

You need one of these bits to counterbore the seats and pig rails to recess tee nuts.

Router
If you don't have one, borrow or buy one.
1/2" straight router bit (no ball bearing collar)

or

1/2" flush trim router bit with shank mounted bearing

You will use this bit to make the handle holes and cut out the access panel opening.  If you don't have a table saw, you can use a straight edge and your router to make square straight edges on plywood.

3/16" Roundover bit

You will use this bit to round all of the exposed edges to make the whelping box more safe and comfortable.

Side Panels (four)

1) All dimensions shown are in inches.  Cut four 20" x 60" rectangles from your plywood.  You want them to be as square and consistent as possible.

2) Lay out the positions for your eight 1/4" holes.  Note that they are 1" from one end and 1-5/8" from the other. This is because the whelping box is designed to be assembled in a spiral pattern.  The spiral assembly lets us make the four side panels and four pig rails interchangeable.  Use one of the corner braces to check each set of holes before drilling.  The brace should be even with the top and ends.  Use a piece of 5/8" scrap as a spacer when checking the left end.  When drilling, use a sharp wood bit and a piece of scrap under the panel to reduce chipping on the bottom surface.

3) It is worth the trouble to make a jig to rout the handle holes.  You will save time and get more accurate and consistent results.  Measure from the cutting edge of the router bit to the edge of the router's baseplate.  This distance is your standard offset for using guides with your router.  On a piece of scrap plywood, draw a rectangle for your 4" x 1-1/2" handle hole.  Draw a larger rectangle outside it using the standard offset you just measured.

Drill several holes inside your inner rectangle to rough out the shape.  Tack or clamp straight strips of wood outside the larger rectangle to guide your router. The lengths of the strips of wood are not fussy.  They will work fine as long as the gaps at the corners are less than about two inches.

Secure the panel so it cannot move, and set your router depth to cut all of the way through the wood.  Rout out the handle hole by running the base of your router along the strips of wood.  You should get a smoothly cut rectangle with straight edges and rounded corners.

Attach a cleat made from a straight strip of wood under the panel 1" from the edge of the handle hole.  If you are using a flush trim router bit with a ball bearing collar, you can remove the boards that are tacked to the top of your jig and use the hole for a guide.  Clamp the fixture on top of your side panel with the cleat against the top edge and you should be able to rout an excellent handle hole every time.


Adjustable Access Panel (one)

Cut one access panel.  The 30" length is not critical, but don't go over 30".   The holes need to match the holes in the "side panel with access cutout" (shown below) as the access panel moves up and down, so make them carefully. Keeping the pairs of holes 27" center to center is most critical.


Side Panel with Access Cutout (one)

Pick one of your side panels and drill eight additional 1/4" holes as shown.  If you clamp the access panel onto the side panel so that it is centered between the handle holes and the top edges are aligned, you can use it for a drilling jig.  

Mark the 8" x 24" cutout and rough it out with a saw.  Use wood strips as shown in previous steps to make guides for your router and rout the opening to finish size.  

Round off the two sharp corners.  A sander will do it very quickly.


Seat (four)

The shape of the seat is not critical, but the sides should not be over 11-1/2" in order to avoid interfering with the side panel handle holes.  Round one corner for safety.  After carefully making the first seat, if you have a 1/2" flush trim router bit you can use the first seat and your router to cut the final three to finish size.  Just clamp the first seat on top each subsequent panel and follow the edge.

The two 1/4" holes can be difficult to position accurately, so wait to drill them until after your test assembly.


Pig Rail (four)

The pig rails are made from 2x4's.  Rabbet each end so that the ends of two pig rails can cross and be the same thickness as the original 2x4.  If you rabbet alternate sides as shown, the four pig rails will be interchangeable.  If you make both rabbets on the same side, you will have two different kinds of rails when you drill them after test assembly.


Rounding The Edges

Keep the full surface of your wooden edge wherever two pieces come together, but round off everything else with your 3/16" roundover bit.  Make sure that you are consistent when rounding the outside end of the side panels.  If any holes need to be filled with wood filler, this is the time.  Sand all parts, except for the seats.  


Inserting Tee Nuts Into Side Panels

With care, tee nuts can be simply pounded into place with a hammer.  The key is to hammer them just enough to make the head touch the wood.  If you try to smash the flat head into the wood, you will break the surface wood fibers and raise some very nasty splinters.  When you assemble the whelping box, tightening the screws will pull the tee nuts tighter.  A better method, if you have a drill press, is to put a 1/2" rod into the drill chuck and use it to press the tee nuts into the holes.

On all side panels, the eight corner bracket tee nuts are on the outside surface.  This surface has one end rounded with the router.  

The side panel with the cutout for the access panel has eight additional tee nuts for the access panel.  These tee nuts are on the inside surface.


Test Assembly and Marking the Seats and Pig Rails

Screw the corner brackets to the side panels.  You may find it helpful to screw them on loosely until everything is together and then snug the screws.

Set each seat on a corner.  Line up the edges of the seat with the outside of the side panels.  Holding the seat in place, use a pencil to trace the hole positions from the corner bracket onto the underside of the seat.

Set the pig rails in position on top of the lower corner brackets.  The rounded edges should be toward the inside.  Push the rails against the side panels and use a pencil to trace the hole position nearest the end of the lower rail

The pig rails are made 1/8" shorter than the inside of the box in order to make it easy to get them into position, so the hole in the bottom rail will be drilled oversize to provide some wiggle room.


Drilling the Seats

Since people will be sitting on the seats, you need to recess the tee nuts into the wood to avoid the edges.  Begin by drilling two1/16" diameter holes through the seat using the circles you drew on the bottom for positioning.  Next, make flat bottomed counterbores about 1/16" deep in the top.  The counterbores need to be at least 45/64" and may be up to 3/4" diameter.  You can use a sharp spade bit or a forstner bit.  After you make the counterbores, drill through from the bottom with your 1/4" wood bit.


Drilling the Pig Rails

Hold a top and bottom pig rail together as they were in the whelping box.  Begin by drilling a 1/16" diameter hole through both boards.  This marks your hole positions.

Drill a 1/2" hole through the bottom rail.  This clearance hole will provide some wiggle room.  

Counterbore the top surface of the top rail as you did on the seats, but 1/4" deep.  This will allow a 1-1/4" screw to get full thread engagement in the tee nut.  Drill a 1/4" hole through.


Finishing

Sand your seats and pig rails, and go over your other parts to make sure that they are smooth and ready to finish.  

If you plan to brush on polyurethane varnish, you can save some time by turning screws into the tee nuts and using them as feet.  This will allow you to flip the side panel and varnish the second side immediately after the first side.

You will get a much smoother finish if you lightly sand the first coat and apply a second coat of varnish.


Feedback

Please let us know if you have problems with these instructions or have ideas for improvement to this design.  If you build a whelping box from our design, send us a photo.  All comments about the whelping box should be directed to kakselsen@aol.com.

See whelping boxes that other breeders have built on the feedback page.

Answers to Frequently Asked Questions


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Last edited January 28, 2012