An Alternate Bending Form

or

$6.49 Vacuum Bag Press

Introduction

My wife came home from the grocery store all excited about these new freezer bags from ZipLoc. They have a built in valve so you can pump out the air with a little plastic pump.  They did seem to attain a fairly good vacuum, and if they'll maintain a vacuum months in the freezer to prevent freezer burn, I figured they might last long enough to laminate veneer together, such as in my spatula project.  Using a vacuum press to laminate the spatula blade makes the bending form a lot simpler to make, because you only have to make a one piece form.  There's  no worry about matching  two halves of a form.  You could just sand out the bandsaw marks without worry of changing the gap between.  No Bondo.

Of course there is no free lunch, and precious little to eat these days for $6.49 (the pump—safer to buy my own—was $2.49 (with two quart bags), and a box of gallon bags was $3.99). You do have to baby-sit the bag and pump it back down frequently at first and occasionally after a while.  I didn't have much luck with polyurethane glue—I suppose that's because of the foaming.  Titebond II worked better but you may get moderate spring-back.

Making the Form

Begin by cutting a wooden blank (construction lumber is fine) about a half inch wider and longer than the spatula blade laminate. 

[FigV01:  The oversize blank cut out of a 2x6]

 

Draw the cutting line on a side of the blank.

[FigV02:  After drawing the cutting line on a side of the blank.]

 

To make it easier to maintain the blank exactly on its side while cutting and sanding, use another piece of construction lumber, cut at a right angle, to make a buttress.  Then fasten it temporarily to the form side, not the waste side, of the blank.

 

[FigV03:  After fastening a buttress to the blank with hot-met glue.]

 

 

Carefully saw along the line with your bandsaw.

 

[FigV04:  Sawing the curve on the bandsaw.]

 

 

Still using the buttress, sand the form smooth.  I used a sanding disc mounted on my lathe, but a drum sander would also work.  Hand sanding would work if you had the time, and a hand-held belt sander would work if you're really careful.

 

[FigV05:  Sanding the form smooth on a disc sander.]

 

Once the form surface looks good (smooth and fair, but you don't have to bother with fine grits), knock the buttress off and the form is done.

 

[FigV06:  The completed bending form.]

 

 

Using

Use your template to cut out 4 layers of veneer and lay them out on newspaper.  Fold a sheet of waxed paper and cut it a half inch wider and longer than the veneer.  Then squeeze out a line of glue on 3 of the veneer pieces and spread the glue with a piece of cereal box cardboard or an old credit card.

 

 

[FigV07:  Spreading glue on the pieces of veneer.]

 

After the glue is spread, stack the layers of veneer.  Insert the veneer stack into the folded waxed paper.  Then use one strip of masking tape to hold the veneer centered on the bending form.

[FigV08:  The Ziploc Vacuum bag set-up with a box of one-gallon bags, the pump, and the bending form with the waxed paper wrapped veneer stack taped on center.]

 

Place the bending form centered in the bag so that it's veneer side up when you can read “Ziploc”.  Zip the bag closed.  Put the bag on flat surface.  Place the pump over the valve (it's in the upper left) and pump out the air using the pump.  Check every few minutes at first and re-pump if necessary.  The interval will lengthen over the next hour or so—you'll be able to tell as the vacuum will still be good).  I suggest you leave the form pumped down for two days, particularly with exotic woods, as that's a lot of glue surface to cure.

 

FigV09:  After pumping down the bag.