CNC-ed Stools

Kenneth & Gabriel threaten to boycott me if they don't get a chair to seat on their next visit to my shop... :(

Buying chair for my shop use just isn't me... Too lazy to hand build some chairs... Procrastination sets in when it is a non-paying design job....

There must be plenty of free chair plans available in the net... so started strolling mindlessly across the WWW....

One will find when one seeks.
A nice stool design in the project page of 100kgarages. I like what I saw here and downloaded the free cad files immediately.

Unfortunately, I can't cut it as it was designed for 3/4 in thick Plywood but I only has 18mm thk MDF. Some customisation is require... but hey, having a free download already save me from loosing gallons of brain juice... can't complain over that...

Without further a do, open up the CAD file, changed the slot & finger joint size to suit the 18mm thk MDF I have, It is always a goof practice to double check the actual thickness for both plywood & MDF before working with it as they can very as much as 3mm... A good a verneer caliper reads 17.4mm averageof 5 readings...
To prevent any possible infringment of trademark of the Makers & the Shopbot, I  removeg their logo from the stool panels just in case & pop in some simple graphic pattern? The added bonus is reduction in weight :)

Then pop the modified CAD file into my CAM program, do some careful tool bit selection, tool feed rate, put in some tabs & G-code is ready for my Mighty Blue Beast.
Load up the MDF sheet, calibrate the positions, turn on the dust collector & I'm off for an extended coffee break.
The stool parts are completed & ready for assembly when I return...
As usual, everything snap-on perfectly.... ;)

This should make Kenneth & Gabriel happy on their next visit ;)...

Children Study Desk & Chair Set

Carving, Engraving & Profile Cutting is fun & the product are pleasant to the eye. BUT mostly useless... Very much like having sex...
This doesn't satisfy my natural crave to build something useful...
I've seen many furniture we made with CNC router... but can this really be done without any further human inteference?
It is unevitable that I set out to build a set of functional furniture... eventually... & that "eventually" came sooner then I could anticipated...
The choice of the month is a Children Desk & Chair set. Why Children furniture you may ask... They are no less difficult then any other furniture & they are smaller (that means less material to buy...) period...
Took some serious effort into research of suitable joineries... After over 2 weeks of toying with various design combination in my head... I conjure enough energy to keep myself nailed infront of the computer monitor for 2 full days to come up with the 1st version...

After a not-so-satisfied prototype & some alteration on the original version. This is my final results. A chair that is ergonimically correct, light-weight & assembled (easily) without glue straight out of the machine. AND (most importantly) they look right to my eye too...

"Flat-packe" profile cut

Now... How should I paint this thing...

MechMate Gantry & Y-Car Assembly

With the availability of CNC laser cut machine, fabricator's life gets a lot easier then it use to be. BUT that doesn't say one gets a free ride when fitting them accurately.`

Here are the laser cut profiled components. Most of them will be "Lego-ed" & weld into usable Monocoque Y-Car chassis & Box Beam Gantry

Level & alignment is of paramount important in this excercise. 

Hence, I build 2 adjustable trestle from C-Channel off cuts.drill & tap M12 holes for attaching adjustable leveler legs.

Setting up the box section beam on  the trestle.

• Using Spirit level to line them on horizontal plane. 

• Align the box section beam by measuring the parallel distance. Comparing diagonal distance to ensure they are square to each other.

• Clamp down to hold the position.

Rubber mallet for fine movement by tapping them lightly on the correct places without damaging the paint work. 

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When you are ready, spot weld to hold the assembly together & check for distortion.before doing the final welding.

Here are the Gantry & Y-car after welding & a coat of red oxide primer on the weld.

Closser view of the Y-car, The original paint was severy damaged by welding spatters....Shouldn't have painted...

.....Nothing I can't sort out with a coat of paint.

Re-Tinker CNC

A quick Google and we have more then a few pages on home build CNC machines of all sort...

There are 4 major components that make up a CNC machine
1) The tool head
2) The linear motion
3) The Motor drive
4) The controller

The tool head is what one decide to use the machine to achieve, be it lathe, milling, punching, grinding... etc. The criteria has not changed much since the industrial revolution and I do not foresee much changes in the near future. The new comers are water jet, plasma cutter, laser cutting, EDM or even 3D printing. These had revolutionized how many things are done and I will expect more to come.

Linear motion used to mean linear motion in X, Y and Z axis, but today, it does include rotational movements around the axis, which are called "DoF" Degree of Freedom. The design considerations involves size & material of work piece, speed, accuracy required, finishing requirements. is how the tool and work piece move with respect to each other.
Fix toolhead with moving work piece? Fixed workpiece with moving tool head? or move both partially?
Tranmission & motion conversion from rotation to linear motion,use mechanism such as lead screw & nut, belt & gear, rack & pinion, gear on chain...
Rail guides to ensure transverse in straight line using linear bearing on rod guide, roller on rail... etc

No drastic changes from what I learn in my school days...
I think I'm still pretty up-to-date in this area.

The greatest different were the controller and the motor driver development and availability.

The drive system, for stepper system, it consist of the stepper motor and driver; for the servo system, it consist of the servo motor, encoder and the motor driver.

Today, micro-stepping driver are available at an affortable price, I think this is the main reason for the CNC boom in recent year. Well within hobbyist pocket size.

Servo system too has become much more affortable, but still has room to go.

Only a few years ago, 'serious' CNC machine are built with a customized controller console with its own computing capacity and PC based controllers are in their infancy.

The controller takes in G-code, A.K.A. command list and send control signal to the driver which consequently operate the stepper motor.

What is G-Code? Its a code that the controller take in for processing and the code normally starts with 'G'. Serious... eg, G 00 means stop, G 19 is move to... etc

There are software that convert .dxf files from most CAD programs to G-code, or one can write the G-code manually. I'm still looking into such programs presently.

Currently, there are many affordable, pseudo-free & free PC based controller software, they all have active supporting forums, the two that cough my attention are Mach3 and EMC2.

Mach3 is a window based controller software, it is free until you decide to "go commercial" with it. USD150 will buy you a pop.

EMC2 is a Linux based open-source controller software under GNU license. This thing runs real time kernal, all the bells and whistle and more...

I think I've reach my typing limit for the day... blurry vision...tired finger joints...