Monday, October 10, 2016

The Anatomy of a Rounded Laminated Gun Belt - Part 1 - The Jig

I'm looking into making laminated belts glued up on a round form with a kydex center ply. The kydex ply will add rigidity and keep the belt from curling over.  Laminating in the round will keep the belt from distorting due to the inner ply of a curve being shorter than the outer ply.  I've estimated that there can be about a 1 inch difference in length in a 41 inch belt depending on thickness.  The distortion in a belt after use, I believe, is due to the two plys working against each other.  I came up with this idea for a curved laminating jig.  I'll mostly be making 1 1/2" wide belts, so above the base, the form will be 2" in height.


Not wanting the finished belt radius to be too tight, a 41" belt circumference will be the size for the first attempt at this jig.  Doing the math, that is approximately a 13" diameter.  If the belt is to be about 1/4" thick, I'll make the base 14" to provide a ledge 1/2" deep.  The ledge will act as a guide to keep the belt edges even.

With a lot of scrap plywood lying around the shop, I decided to put it to good use.
Had to biscuit join two pieces for the base.
The circles will be cut with a table saw.  Using a sled (this one I've had for over 20 years) mark two radius points, one for the 13" diameter forms (6 1/2" radius) and one for 14" diameter base (7" radius).  Do this perpendicular to the blade.
Pilot drill and drive a screw into the sled.

Mark the center of the boards.

Drill a larger hole in the wood for the forms and the base to be a friction fit for the screw from the sled.  The wood should not have any play on the screw, but should be able to rotate freely.

To keep the screw from protruding through the bottom of the sled, use shim washers.

For the first cuts, the wood should be screwed down so that there is a fair amount of friction preventing the wood from rotating as it comes into contact with the blade.  Start by cutting off one of the corners.  Hold the wood firmly, any rotation of the wood during the cut will cause the wood to bind against the blade.

Continue cutting off the facets.

Keep cutting off facets until fairly round.

Now loosen the screw so that the board turns freely on the screw.  Holding the wood against the sled, bring the sled toward the blade until the wood engages fully with the blade.  Slowly rotate the wood into the blade (not with the rotation of the blade) until you have a circle.  Do this for all of the form pieces.

For the base, move the screw into the 7" radius hole on the sled and proceed as before.

Once all of the circles are cut, its time to glue, nail, and clamp the form boards together.  We'll use the sled screw to align each circle to the other, one at a time.  Before gluing, rotate the two boards until they edges are most even, then mark with a pencil.  Now remove the screw.

Spread a good woodworking glue on the mating surfaces of the first two boards.  This is the best use for credit cards that I've come up with.

Place the mating surfaces together and drive the center screw back in, align your pencil reference marks, and then nail the boards together.  I always toe-nail when pinning things together.  The outer row nails angle toward the center and the inner row nails angle toward the outer row.  Remove the screw.

I used three form boards which yielded about 2" of height.  Once all three pieces were nailed, I clamped the assemblage all around.  This will ensure that all surfaces are flat and well glued.

After a couple of hours, I used 60 grit sandpaper on a block to smooth any irregularities in the rounded surface and then eased the top edge to prevent the surface veneer from chipping.


Sand the curved edge of the base board and ease the top and bottom edges.  Then layout your screw locations for mounting the base to the form.

Center and mount the base to the form again using the sled screw.  Then drill pilot and countersink holes.  Use flat head construction screws.  I decided to screw the base on in case there is a need to increase the height of the form or to increase the diameter of the base.

Top portion complete.

I center drilled the jig and used a through bolt to secure it to a board that can be fastened to a bench to create a stable lazy suzan.  I then bored some holes with a forstner bit deep enough to use a clamp to hold the ends of the leather together as the plies are pressed together while rotating the jig.

The ledge on the bottom of the jig indexes one edge of the leather straps.  Once dry, the belt will be run through the strap cutter again to flush the top edge prior to belt sanding.

Wednesday, October 5, 2016

The Anatomy of a Rounded Laminated Gun Belt - Part 2 - The Belt

Here is part 2 of 2 on making a round leather laminated gun belt using the round laminating jig...

Create the straight edge using an aluminum rule and a 60mm rotary cutter.  I'm liking using the rotary cutter these days for the initial cut.  The following cuts are all made with the strap cutter set to, in this case, 1.5".

Apply two coats of contact cement and let dry for 5-10 minutes until tacky (not wet).

I center drilled the jig and used a through bolt to secure it to a board that can be fastened to a bench to create a stable lazy suzan.  I then bored some holes with a forstner bit deep enough to use a clamp to hold the ends of the leather together as the plies are pressed together while rotating the jig.

The ledge on the bottom of the jig indexes one edge of the leather straps.  Once dry, the belt  will be run through the strap cutter again to flush the top edge prior to belt sanding.

The belt will be left in the clamps for at least a couple of hours prior to trimming.

 Belt sand edges flush, block sand with 150, hand sand with 320.

 Spit both ends of belt to reduce thickness at buckle closure.

Punch buckle end of belt.

 Measure belt to length and punch.  This is an English Taper punch.

 Bevel round the outside edges; front and back.  This is a No. 3 round bevel.

 Stitch groove the belt; front only.  This is a 3/16" set back.

 Bevel and groove the keeper; front only.  This is an 1/8" set back

Edge dye the belt and keeper prior to burnishing.  Some burnishing waxes (beeswax) don't allow proper stain penetration.  Allow to dry thoroughly.



More to follow...

Hope this helps,
Mike

Wednesday, August 10, 2016

DIY Hot Box for Drying Leather

I decided to build a hot box to speed up the drying time between processes during leatherwork.


Dwight and some other kindly leather working souls are engaged in a thread over at the leatherworkers.net forum and it finally inspired me to research and create one of these little time saving devices of my own.

The following will provide you my results and insights into the process.  Bear in mind that this is a work in progress and things are subject to change as the hot box moves from concept to reality.

I'll update photos as construction proceeds.


LED Digital 110V Temperature Controller MH1210F

150W 110V Ceramic Heat Emitter

110v AC to 12v DC Transformer (2 Amp)

Pulse Width Modulators (Fan Speed Control)



Hot Box Wiring Schematic w/MH1210F Thermostat and Optional PWM Fan Controls

Hot Box Dimensions Front
Note: Width dimensions of opening are to accommodate lighting panel grid.

Hot Box Dimensions Back

Cut sheet for a 24" x 90 panel (modified cabinet depth to 11 3/4" to use what I had on hand)

The following photos show the plywood assembly.  Note the holes cut into the face panel for the controls.



Used a length of 1/4" Pex toilet fill line cut into 2" lengths as stand-offs.  Tapped the plywood and mounted the CPU fans with 4" 8-32 round head screws.  Had a couple of old porcelain medium base lamp holders.  Ceramic heat lamps installed.

View of the sub-top with holes cut for wiring.

110V AC to 12V DC transformer wired up.

Doors cut and mounted.

3/8" plywood back panel glued and nailed.  Note access cut-out in panel for wiring.

Pulse Width Modulators installed and tested with fan... works like a charm.  Here you can see the thermostat being wired.  I used 18 gauge stranded wire throughout.

Single gange cut-in box installed which will house the timer.  Colored tape was used to mark the hots, neutrals, and grounds.



Here, 10-24 tee nuts are epoxied, then screwed onto the back of the cabinet.

Came up with an idea for my pegs using 10-24 all thread cut to 6" lengths, covered them in heat shrink tubing, then installed brake bleeder caps on the ends.  NOTE: I had tried to epoxy wood dowels sections to the heads of flat head screws, but the glue failed.

Shelves cut to size... Can't remove without flexing the shelf or removing the door.  I may add some extensions to the shelf cleats to solve this problem.

 The holy grail has been reached... 140º F...!!!


Some testing results:
  • Changed to all-thread pegs... working great now.
  • Shelves can't be removed without flexing or removing doors.  Will glue some extensions to the shelf cleats.
  • Thermostat read out is consistent with oven thermometer.
  • 120º F - 15 minutes
  • 130º F - 22 minutes
  • 140º F - 30 minutes
  • Thermostat interval 140º to 137º - 2 minutes
  • Reheat to 140º cut off - 3 minutes
I may change the cycle interval from 2 degrees to 5 degrees to reduce wear and tear on the thermostat.


Hope this helps,
Mike