Inlays with F-engrave

F-engrave 1.73 is being used in this blog post.  The YouTube videos are excellent but the gui has changed enough to need a bit of explanation.

If using linuxcnc: settings -> general settings -> un-check 'suppress comments' can be useful.

Click on any image to enlarge.

The dxf file is a simple set of rectangles.

The main items of interest are the image height and the v-carve selection checked.

In General Settings you may want to enable center format arcs.

The origin is set to center in this example.

Settings used as shown.

Calculate v-carve.

Calculate clean-up.

Save clean-up gcode.

Save v-clean-up gcode.

In this example cuts were deep enough that no clean-up was needed.

Close settings window.

File menu -> save gcode as "name"_female.  This is the v-carve tool path.

Next...

Mirror image.

Re-open v-carve settings.

Check 'add box' and 'prismatic'

Set gap, in this example 1/16"  (-0.0625)

Calculate v-carve.

Calculate clean-up.

Save clean-up g-code

Save v-clean-up gcode.

Close vcarve settings window.

In main window: File menu -> save gcode

Save as "name"_male.  This is the male v-carve path.

There will be up to 6 g-code files.  If using a tool change routine or a tool changer this can be reduced to 2 files using the Linux cat command.  Remove unneeded M2's and add T# and M6's as needed.

For illustration purposes STL files were created using Camotics.

Meshmixer was used to mate the 2 STL files.  The result was brought into QCad to add the dimensions.  If the result isn't exact to the decimal place blame the weird mix of software.  The gap is very close to the intended 0.0625".  This gap provides space for a saw blade between the 2 surfaces.  See why sanding away the pointy tops of the male part before clamping/gluing is a good idea ?

A small note on using F-engrave for inlays: the software calculations are based on a cutter with a true point.  If the cutter has any amount of flat on the end the tool height must be adjusted accordingly.  Even a flat of 0.030" can result in a failed inlay.  Other pit-falls are an off-center cutter point,  a spindle with run-out, and v-bits labelled with a  nominal (not exact) included angle

First Try at a Lithophane

 

The creator of the image above posted it to an internet forum.  I'm assuming it was provided for free use for non-commercial purposes.  This type of image is ideal for creating a lithophane.  Unlike like some of the finely detailed lithophanes posted elsewhere this image won't require micro sized cutting tools or endless hours of cutting.

Recently I've found a source of Corian cut-offs at near give away prices.  Corian is a brand name Solid Surface Material which has translucent properties if not infused with dark pigments.  The piece used in this post is some shade of white.

   To get the lithophane effect the Corian was first milled down to a thickness of 0.130".  As shown in the screenshot above the 1/8" ball end mill will be carving to a max depth of  -0.100 which means only 0.030" of material will remain at the deepest parts of the carving.  The settings shown in the image above are the exact settings used.  A roughing pass was also used but is not shown here.

Camotics was used to check the gcode before cutting.  Camotics can be a bit deceptive depending on how the image view is rotated.  The first image shows the features on the chin a forehead as depressions:

in fact they stand proud of the surface as shown from this angle:

Below is the finished item back lit with a florescent light which makes it appear quite yellow.  When illuminated by natural light, such as hung in a window,  it has a bluish-white hue which I find more attractive but more difficult to photograph.

More Wooden Toys

This post is a fan tribute of sorts.

I've built several projects based on files shared by trinityscsp (Juarez) via GrabCad.  A few are pictured below.  Juarez, if you ever stumble across this site, thank you for your generosity.

Farm Truck

https://grabcad.com/library/old-farm-truck-1

Speedster

This one is a work in progress.  Still looking for suitable material to make the fenders
https://grabcad.com/library/speedster-wooden-toy-1

Sports Car

https://grabcad.com/library/sports-car-wooden-toy-1

Buggies

https://grabcad.com/library/baja-buggy-wooden-toy-1

All together with the truck hauling a 2 litre bottle for a sense of scale.
The camera seems to be adding some amount of a distorted perspective to all of today's photos  but I've never claimed to be a photographer of any skill.

Easy Name Puzzle

If you have a CNC router this personalized gift is an easy make. This project uses maple for the letters and Baltic birch ply for the cat and base. The font used is 'Life is Goofy' downloaded from one of the popular free font websites. This font was chosen for ease of cutting and to my eye it looks like something that would feel good to a toddlers hands. The cat was a Jpeg named 'peeking cat' found with a Google image search.

Inkscape was used for most of the design work.  I'll assume if you want to duplicate this project you already know how Inkscape handles bitmaps and fonts. If that's assuming too much the internet has plenty of tutorials on those topics.

The puzzle pieces should be a slightly loose fit unless the toddler is being provided with a hammer 👶.  To achieve this fit Inkscape's Linked Offset feature was used along with Guidelines to measure the amount of offset.  The Offset in this case was actually an inset of approx 0.025".  For the puzzle pieces delete the original outline (aka path) and save the inset. Save the original outline (aka path) as a separate file for cutting the pockets. 

The work in Inkscape results in 4 svg files:
#1 cat svg non-offset for pocket
#2 letters svg non-offset for pockets
#3 cat svg offset (inset) for puzzle piece
#4 letters svg offset (inset) for puzzle pieces

These 4 svg files are imported into Fusion 360.

Create the plywood base in Fusion 360.  Import and align svg files #1 and #2.  These files are cut with a pocketing tool path.  Outside contour  the base to it's final shape.

Create another file in Fusion and import svg file #3.  Cut the cat with an outside contour tool path.  Follow the same procedure for svg file #4 to create the letters.

The puzzle pieces should protrude far enough above the base surface to allow grasping by little fingers.  Paint the puzzle pieces on the top side only.  This will reduce confusion with those letters which appear to be reversible.

Btw: Fusion 360 can occasionally be stubborn when trying to extrude imported svg files.  If this happens try converting the svg to dxf using QCad.
 

A Wooden Gear Clock

This is my take on Brian Law's Clock #1

https://www.woodenclocks.co.uk/clock-1/

I converted the free pdf linked above into 3D files using inkscape and Fusion 360.  For the amount of effort involved it would be sensible to pay the man.  What can I say ?  I'm cheap and enjoy a challenge.  Also I've paid for the clock #22 plans so it's not total freeloading ☺

All gears are birch ply cut with a downcut spiral to reduce tear out.  Maple was used for the escape wheel and pawl resulting in smoother sliding surfaces than possible with ply.  The frame is oak.  The drive weight was a rolling pin in a previous life.

A good running clock doesn't rely on tight tolerances, in fact a bit of slop is necessary.  The gears don't need to be tightly meshed because there is no change in the direction of rotation.  The shafts need a bit of a loose fit in the frame due to the 'living' nature of wood  and frame sag caused by the drive weight.  This is one of the reasons why my clock uses no bearings.  The only place I did consider bearings is on the shaft supporting the drive weight.  One  place precision does matter is the bore of the escapement wheel, this bore must be as close to centre as possible.  A off centre or out-of-round escapement wheel will not provide a regular tick-tock beat and may not run at all.

Friction is the enemy.  Clocks are gear-up drive trains where wheels (the larger gear in a pair) drive pinions (the smaller gear).  Following the gear train from the large wheel at the weight pulley to the escapement wheel speed is gained through each succession of gear pairings.  This increase in speed comes at the expense of torque.  My clock powered by a 5 lb weight  can be stopped by a feather at the escapement wheel ... literally.  Friction must be reduced where ever possible and this is especially true for the top shaft where minimal torque is available.  The shaft are highly polished where free rotation is needed and the non-fixed bores are lubricated by wax crayon shavings.  Gear teeth are sanded smooth.

My clock is slightly different than the original design.  The shaft sleeves were not used.  The gears are either interference fit to the shaft or free rotating.  I'll leave the reader to figure out which fit was used on any particular gear.  The pinion on the lowest shaft has been pinned in place.  Two threaded rods tie the frame together rather than the fussy pins+pegs seen on the original.  One weak part of the original design is the pawl on the winding ratchet.  This pawl needs to be heavier in cross-section or completely redesigned.  It's holding power is marginal at best and if it slips the drive weight will crash to the floor.
                                                                                                                                           

   Links of possible interest:

a good explanation of clockworks
https://www.finewoodworking.com/2009/01/07/designing-wooden-clockworks

Lots of general information
http://garysclocks.sawdustcorner.com/

A wealth of information if you dig deep enough
https://lisaboyer.com/Claytonsite/Claytonsite1.htm

Forgot to mention my clock runs 9 hrs before the weight touches the floor.  Accuracy is reasonable but for time keeping
I recommend  something from Walmart.

Son of Sisyphus

I've been a longtime admirer of Bruce Shapiro's kinetic art and his marble-in-sand machines in particular.  It's now possible to buy his creations from sisyphus-industries but this is a DIY blog.  Plus I'm cheap.

Electronics to drive small stepper motors can be had for very little money thanks in large part to the 3D printer revolution.  This build uses an Arduino Uno with a cnc shield and A4988 drives.  The 3 steppers are Nema 17 and the power supply is an old computer psu.  The software is grbl using bCNC as a sender.  Grbl has the ability to slave 2 motors to 1 axis which allowed a  build with very little mechanical rigidity.

A view from below

2 motors slaved as 1 axis

The construction is very simple. Gt2 belts and pulleys, Oilite bushings on hardware store grade cold rolled steel shafts, a coil spring and a magnet.
The top side of the table has a layer of baking soda and a 3/4" steel ball. A strip of LED lights add colour and shadow effect.

Compared to the commercial offering this one is much noisier and noticeably less smooth in it's motion.  On the other hand it's much less expensive and has all the same capabilities.

first test run

Senseless Fun with Probes

 A probe can be as simple as a nail, a spring and a length of copper wire.  I had some unused items in the shop which led to a bit of overkill.  The large metal thing in the photo is an old PC power supply.  Over to the left is a board to read pulses from a photo interrupter.  In the centre is a dial indicator with a metal tang screwed to the top of the plunger.  This tang breaks the beam of a photo interrupter whenever the plunger is forced upwards.  The dial indicator is handy for quickly finding high/low spots in a sheet of material.  For actual probing the nail and spring mentioned earlier would serve the same function.

 This is the bowed wood that was probed.  The shiny bit is a quarter to give a sense of scale.  A size for the engraving and a centre origin point were decided on at this time,  the origin point was marked with a felt pen.  The  reason for marking the origin will become clear in the next step.  To probe a grid of points smartprobe.ngc was used,  this is included with the Linuxcnc package.  The probe work piece coordinates were zeroed at the the centre of the material.  Z zero is set to the photo interrupter trigger position at this origin which is also the high point of the material. 

The text file created looks like this:
-3.000000 -2.750000 -0.404709
-2.800000 -2.750000 -0.346447
-2.600000 -2.750000 -0.292887
-2.400000 -2.750000 -0.244701
-2.200000 -2.750000 -0.201554
etc etc etc.  It's pretty dull reading but it can be put  to use or at least something resembling a use.  It's time to visit ScorchWorks.
http://www.scorchworks.com/
The 2 Scorch programs used in this post are F-engrave and G-Code-Ripper.

The smiley moon started as an SVG from OpenClipart.  F-engrave needed a DXF file so InkScape was used for the file conversion.  I won't go into how the g-code file was created in F-engrave except to say it's about as simple as this type of software gets.  The critical point is the origin and scale are the same as the grid probe file.

With a probe text file and an engraving g-code finished it's time for G-Code-Ripper.

A: open g-code file
B: open probe text file
C: save the adjusted file

That's it.







Remember the felt pen mark made earlier ?  That's where the cutter was touched off for the engraving work piece coordinates.  It was done this way because the probe wasn't in the spindle or even near it.

Anyone tempted to try this is advised to go to YouTube where there are several examples.  The software has a clever probe function which wasn't used in this post