Tag: MK4

The Handi-Quilter HQ Sixteen rides on two tracks along the 11 foot length of the table, with an unsupported 8 foot span between the legs on each end:

Contemporary versions of the table have support struts in the middle that our OG version lacks and, as a result, our table had a distinct sag in the middle. During the course of aligning the table top into a plane surface with tapered wood shims, I discovered the floor was half an inch out of level between the table legs.

Now that the whole thing has settled into place, I measured the shim thicknesses and made tidy blocks to replace them:

The OpenSCAD code has an array with the thickness and the number of blocks:

SHIM_THICK = 0;
SHIM_COUNT = 1;

Shims = [
    [3.5,1],
    [5.0,3],
    [6.0,2],
    [6.5,1],
    [7.0,1]
];

Yes, I call them “blocks” here and wrote “shims” in the code. A foolish consistency, etc.

The model is a chamfered block with a chunk removed to leave a tongue of the appropriate thickness:

Building them with the label against the platform produces a nice nubbly surface:

The labels print first and look lonely out there by themselves:

The rest of the first layer fills in around the labels:

Putting the labels on the bottom makes the wipe tower only two layers tall and eliminates filament changes above those layers. Those eight blocks still took a little over three hours, because there’s a lot of perimeter wrapped around not much interior.

Having had the foresight to draw a sketch showing where each block would go, I slid one next to its wood shim, yanked the shim out, and declared victory:

The tension rod welded under the table rail prevents even more sag, but the struts under the new version of the table show other folks were unhappy with the sag of this one. Another leg or two seems appropriate.

With the table leveled and the surface aligned, the HQ Sixteen glides easily in all directions. The result isn’t perfect and Mary keeps the anchor block at hand, but the machine now displays much less enthusiasm for rolling toward the middle of the table.

The OpenSCAD source code as a GitHub Gist:

My version of a mount for the HQ Sixteen’s “stylus laser” clamps a 1 inch polypropylene ball between two plates:

The plates have a sphere subtracted from them and a kerf sliced across the sphere’s equator for clamping room:

Given that this is a relatively low-stress situation, I embedded BOSL2 nuts to produce threads in the plate rather than use brass inserts.

The side plates start as simple rectangles:

Subtracting the electronics pod shape from those slabs matches them exactly to the curvalicious corner:

The weird angle comes from tilting the mount to aim the laser in roughly the right direction when perpendicular to the plates:

That angle can be 0° to 30°, although 25° seems about right. The slab sides neither stick out the top nor leave gaps in the corner over that range, after some cut-and-try tinkering sizing.

One of the M3 screws just did not want to go into its hole:

A bad day in the screw factory, I suppose.

The OpenSCAD source code as a GitHub Gist:

Mary’s practice quilts on the HQ Sixteen suggest locking the machine’s wheels will simplify sewing a line parallel to the long edge of a quilt parallel to the table, but contemporary “Channel Locks” fit newer machines with larger wheels than on this one.

Duplicating those rings in a smaller size seemed both difficult and not obviously functional, so I built a pair of blocks to capture the wheel on its track:

The wheel sits in a recess holding it just barely above the track surface, so the (considerable) weight of the machine holds the block in place.

Because lines on quilts have precise placement and Mary has quilting rulers within reach, the block measures exactly two inches from the point where it first touches the wheel to the center of the recess:

She can then lay a ruler on the quilt, roll the machine front or back two inches, slide a block against each wheel, then roll the machine up a slight incline until the wheel drops into the recess:

The spacing looks like this:

The usual 3D printing process puts 0.2 mm steps along the ramp, but they’re almost imperceptible while rolling the machine:

The ramp slope is all of 1:20 = 2.5°, so pulling / pushing the machine requires very little oomph.

I put thin cloth tape (approximately friction tape, but with real adhesive) on the bottom of the block by the simple expedient of sticking it to the block and scissoring off the excess. A little compliance between the block and the track prevents the hard plastic shapes from sliding more easily than I’d like. If your tape is thicker than mine, knock a little off the WheelZ value.

The OpenSCAD code can produce shapes to laser-cut an adhesive sheet, although stacking a foam sheet will definitely require height adjustment :

The OpenSCAD source code as a GitHub Gist:

After watching the thread pull off the spool around the vertical spool adapter in an increasingly tight helix, I built a horizontal adapter:

The thread now pulls off perpendicular to the axis, the way we thought it should, and the helix is gone.

The adapter base plate fits snugly over the vertical pin, with the lip over the edge stabilizing the whole thing. The spool fits on a ¼ inch acrylic rod tightly press-fit into the side wall and, although it’s not shown here, the vertical adapter press-fits onto the end of the rod to keep the spool from wandering off.

The solid model shows the arrangement:

It builds standing on the wall to prevent any significant overhang:

So we’ve reconfirmed our original knowledge that ordinary thread spools must feed off the side, not over the top. Living in the future with rapid prototyping and simple production is good!

You can buy a Horizontal Spool Pin Clamp, but what’s the fun in that?

Fun fact: although the vertical pins on the machine are ¼ inch in diameter, the thread on the end is neither the obvious ¼-20 nor the second-guess 10-32. Instead, it’s M5×0.8, perilously close to the 10-32 thread used in the handlebar setscrews. Don’t apply brute force when this thing doesn’t screw neatly into that hole.

The OpenSCAD source code as a GitHub Gist: