PETE WARD

"WELCOME TO MY OUTDOOR WORLD"

"Jeff Strubbergs Lamination Grinder"

This project goes together really quickly.

Jeff Strubberg is the author and designer of this great project.Thanks Jeff for sharing this with us.


Materials List:

1. a drill press

2. a 3" drum sander with a 60 grit drum

3. 10" x 24" x 1 1/2" stock (i used two pieces of 3/4 plywood glued up with TB3)

4. 20" x 3" x 3/8" stock (i used a piece of 3/8" plywood)

5. a handful of 1 5/8" drywall screws

6. glue

7. a hunk of duct tape, the 2" wide stuff



This project goes together really quickly. The absolute most important aspect is making sure your fence is 90 degrees to the bed of the  jig. Make sure your square is accurate and be picky! Don’t settle for anything less than perfect here if you want quality laminations.

 First, let’s get the rough cutting out of the way. Cut a 3 inch piece of plywood 20” long, then cut it in half.

Next, set your rip fence 3” from the blade of your saw, then tilt the blade to 45 degrees with the  top of the blade AWAY from the rip fence. Did you put the fence on the wrong side? Back up, switch sides and set it up again. We want to end up with a 3” tall fence with a nice 45 degree angle across the bottom. Once you have the saw set, rip the 10” x 24” x 1 ½” stock lengthwise. Next, we need to put a slot across one face of the 4 ½” piece of stock. This cut will allow the bolt protruding from the bottom of your drum sander to travel across the jig. Without it, you won’t be able to get the drum anywhere near the fence of the jig. Use whatever method you are comfortable with to achieve a Ύ” wide by ½” deep slot across the centerline of the width of the 4 ½” stock. I used my table saw with the blade set to a depth of one half inch and dadoed the slot out one cut at a time.

 

 "Base" and "Fence" of jig body with 3/8" spacer material

        Now you will have two pieces, one approximately three inches, the other approximately four and a half inches, both with a nice 45 degree angle on one face. We need to turn those two pieces into a single assembly with a perfect 90 degree angle. Here is a super-simple trick I picked up from a woodworking magazine. Lay both pieces on your workbench with the longest edges of the 45 degree faces touching and the hollow created by the two angles facing down towards the top of your workbench. Rip off a piece of duct tape 24 inches long and run it down the seam between the two pieces. Now, carefully turn the two pieces over and run a bead of glue along the inside of the 45 degree faces. Fold the assembly up to form a 90 degree angle with the duct  tape playing the part of temporary hinge. Secure the assembly with a wrap of duct tape on either end. See the photo for an illustration of the technique on a piece of scrap.

 

  Now get that square out and look things over. You did  check to be sure your square was accurate, right? For those of you who don’t know how, take a piece of stock that you are SURE has one straight edge. Use your square to mark a pencil line across the stock with the square laying down that straight edge. Now flip the square and see if you can use it to trace  down the same line. If you can, your square is accurate. If not, you can adjust  the square with a punch. Give a light tap on the punch at the inside of the angle of the square to spread it, a light tap on the outside of the angle to close the angle up. Once you are sure your square is accurate, lay it up in the angle you just created by joining the two 1 1/2'” pieces of stock and put a small flashlight behind it. Look for light coming through, indicating gaps  you will have to correct. When you find one, figure out where the high spot is  on your soon-to-be lamination jig and correct it with a piece of 80 grit sandpaper on a level sanding block. I found the top edge of my fence was just a hair proud. It took about five minutes of sanding and re-checking with the square to true things up. Once you are sure the angle is a true 90 degrees, pilot drill six holes through the 45 degree angle of both pieces and secure them with drywall screws.

Next, mark back two inches either side of the centerline on the inside edge of your new jig body. Take the two pieces of 3/8 stock and position them along these marks and tight to the fence section. Secure them with glue and small brads or a few more drywall screws. This creates a hollow that covers the non-sanding bottom edge of the drum sander and allows us to sand the entire lamination in a single pass.

 

 

 

 

 

The only thing that remains is to rig up a way to attach the jig body to your drill press table. My table had two long slots in it already, just begging to be used. I chucked the sanding drum in the press, set the jig body in place and used a sharpie marker to mark a point in either slot, as  far from the front edge of the table as I was comfortable with. I then drilled two 5/16” holes through the jig and attached it to the press table with a pair of Ό” x 2 ½” bolts. I used wing nuts to tighten the assembly down in order to allow for rapid adjustments. A pair of fender washers and a lock washer on the underside of each bolt is a wise investment.

 

 

 

Your lamination jig is ready to use as soon as the glue has dried. Set the jig on the press table and secure it loosely with the two bolts. Adjust the jig so that the drum sander rides in the slot left between the two 3/8 spacers and with the bolt on the bottom of the sander riding in the slot you cut in the body of the jig. If you have a lamination you are trying to reproduce, lay it tight to the fence and adjust the jig body until you can just drag the lamination back and forth while holding the drum still. Now turn on the press and slowly, SLOWLY feed your lamination stock along the fence and into the drum. If the press bogs down, you are trying to remove too much stock at once. With this size motor, you are limited to around .010 per pass. If you cut your stock to 1/8” on the table or band saw, one pass is all that will be required. Feed the lamination stock into the drum as slowly and consistently as you can. I flip the lamination and make four passes, two on each side, rotating top and bottom to even out any inconsistency in the fence I was unable to detect by eye. My method of adjustting the thickness of the finished lam is pretty complicated. A tap from a claw hammer along the front of the jig widens the gap between fence and drum by a bit less than .005, a tap on the back face of the jig closes the gap by a similar amount.

 

A couple of things you may want to do to make this rig more pleasant to use. First, if you have a shop vac,use a 2” spring clamp to attach it to the edge of the jig and pick up the volume of dust grinding laminations makes. Second, some sort of feather board or friction roller on either side of the sanding drum would further reduce chatter and make grinding a one-handed operation. A ½” eye bolt in the edge of the bed of the jig will allow you to hang the assembly on the wall when it’s not in use. I plan to finish sand the whole jig and add a few coats of polyurethane, both to make things slide more smoothly and to aid in dust cleanup.

 

 

                                                  Ought to be a couple of bow limbs in this hunk!

 

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