An interesting article, particularly the difference in microscopic view of a piece of timber that is planed vs one that is sanded.
Here is my latest project, ready for the next edition of The Shed magazine.
It is a coin storage cabinet, with spaces for 1200 individual coins, stored in acrylic trays. It has a curved top (using kerfing) and tambour door. By replacing a 6mm thick tray with two sheets of 3mm clear acrylic, bank notes could also be stored and displayed.
Each tray has a tab with a descriptor of the tray engraved in it, such as “Australia 50c Commemorative”, and each coin slot is sized to the specific coin that it is to house.
When the edition of The Shed comes out (soon), the article goes into detail how it was made, using both CNC and non-CNC techniques.
I recently met with a new owner of the SawStop, and took them through some of the specifics of the machine, including some of the basics of safe operation of a tablesaw. As they were an experienced operator, the focus was certainly around the brake mechanism.
Six months later, and I get a call. Turns out the SawStop mechanism got tested for real. Scared the bejesus out of him – not only when it activated, but more fundamentally, that it happened at all. So we are going to have another session, and this time running through the A, B, Cs of tablesaw use.
Had my own experience last weekend. Not of the SawStop mechanism, but a reminder of basic safe operation.
I try to ensure that I am not standing directly in line with the blade when it is cutting. That isn’t always possible, but it is a good practice, and this time was no exception. I was standing to one side while ripping a piece of timber, and a piece of the offcut splintered from an unknown internal fault in the timber. It got spat out by the blade, and sailed right past my ear. Close enough for me to hear it pass by. Close enough that I felt it brush the ear.
Reinforces why I like standing to one side while cutting! Even if it had hit, it is unlikely to have done any damage, but it is a good reinforcement why we practice safe use. And why eye protection is mandatory.
I finished off the cut – nothing wrong there, so the technique was fine. It really came down to a weakness in the timber.
As much as I was out of the line of fire, it was a full-depth cut. And while having the riving knife fitted helps protect against kickback, having the full dust guard fitted when it was appropriate for it to be used would have prevented this happening at all, at least as far as having a small missile launched in my general direction goes.
I’ve been trying out some different materials on the CNC, using some of the other router bits in the Toolstoday.com Master Collection.
Using the 51411 “Spiral ‘O’ Flute” upcutting plastic cutting solid carbide bit, I tried a bit of polycarbonate. This is 3mm thick, which ideally suits the plans I currently have. I started with some clear, to try it out as much as anything. I slowed the feed rate down (given I am currently restricted to 12000RPM), then slowed it down further. I found it ran pretty smoothly at 10mm/sec. I plunged at the same speed, but for future reference, ramping the bit down should be a better approach. With a 1.5mm depth of cut, things worked pretty well.
My next endeavour will be to approach the same model again, but choose different materials for the different components. So far I have about 4 different polycarbonate colours (one being fluoro), some aluminium and brass in the design. Hopefully it will all work together and not look too mismatched.
Clear red poly for the flames, aluminium for the nostril smoke, and for the centreline of the body (up to and including the tail), brass for the small plates on the underbelly (like Smaug and his gold-encrusted hide), and a combination of solid green poly and fluoro green poly (for the scales, and head).
While I wanted to wait until the project was complete before showing it, I have just finished a mammoth step, so decided to share the progress.
Starting with a slab of American Walnut
Then, after 24 hours of solid routing on the Torque CNC
And a quick initial application of Danish Oil (as much to find where I need to do additional sanding), the result is starting to show some promise. (The gauges are only to test fit, they will not join the project until it is pretty much complete). The top station (the celtic design within a circle) is not just decoration, it will also be a clock. The gauges are all high quality German-made ones I bought from Carbatec.
Big push at the end coming – how unusual………
Using the same steps discussed in the last entry, I have taken a vector drawing of a Celtic Cross (created by “CarveOne” on the Vectric Forum), and produced a 3d rendering of the design.
This is the first time I have really tried using multiple paths on the same object.
The first pass was a roughing pass – used to remove as much of the unwanted timber as possible with a strong router bit, and higher feed rates to perform the task quickly.
For this I used the 46294 3D carving bit from Toolstoday.com It has a Zirconium Nitride (ZrN) ceramic coating, so this bit is also appropriate for routing in aluminium, brass, copper, cast iron and titanium alloy. It makes very short work of the camphor laurel!
The final design was then carved using the 46282 3D carving bit. This has a 1/16″ diameter tip, so can really get into the details. Even so, there is a bit that is even finer, if even more detail is required (with a 1/32″ round nose tip).
I was using these at around 80mm/sec.
Once the design was cut, I swapped over to a solid carbide 1/8″ upcut bit to first cut around where the gaps were meant to be inside the design, and then to cut around the outside, down to about 12mm deep.
For a sense of scale, the cross is about 300mm high, and 200mm wide. Straight off the router bits, there is no need for sanding where the carving bits have been. There is a bit of feathering on the outside of the cut out, but that is both a function of the timber, and insufficient router bit speed.
I deliberately didn’t cut all the way through the timber, so there was no need for tabs to hold the cut pieces in place.
To release the cross from the surrounding material, I turned the whole thing over, then ran a basic flattening profile on the back, taking off 2mm at a time with a surfacing cutter – using the RC2248 replaceable tip cutter.
Once this cut down to the required depth, the cross was released.
Each project presents different challenges, so I get to know more and more about how to use the CNC router effectively, and how to incorporate it as another workshop tool.
I had a look back at some tests I did on the CNC Shark using 3D carving bits – the finish I am achieving here is chalk and cheese compared to my early experiments. I don’t know if I can attribute it all to the platform, but having such a solid, heavy duty CNC router certainly is not harming the finish that I can now produce!