Sabretooth

Some photos taken during the shoot of Episode 112

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Plans from MakeCNC

Oxygen

Had a young fella visiting with his family today.  I know it was a waste of breath, but I had to ask him “Do you like dinosaurs?”

It’s like asking a human if they need oxygen to live.

So the answer was a given.  But he wasn’t expecting what came next.  I handed him a set of about a dozen different dinosaur plans, and suggested he choose one.  After a meticulous sort and selection (he’s all of about 4!), one was chosen – a triceratops.  Has big horns for hunting I think was the rationale.

No problem, let’s go make it.  So first, camped out on the lounge floor we loaded the plans into the computer, fitted them to the board size (nesting), and set the required tabs.

Then it was off to the shed, with a small entourage in tow.  While the kids watched, I set the CNC up for the job, explaining what I was doing each step.  There was a board placed on the ground a short distance from the work area, and strict instructions that only I could step over that board.  A small step ladder placed on the other side of the board was a very convenient lookout, and it was duly manned for pretty much the entire time.

As each board was completed (this particular pattern required three 900x600x6mm MDF boards) (and yes, dust extraction and air filtration were on), the entourage were involved in popping each piece loose, then each piece was duly handed to me one at a time so I could sand off the tabs on the disk sander.

The young fella was funny.  He couldn’t get over that we were making ‘his’ dinosaur.  Nor that it was going to be ‘big’.  After all, what does ‘big’ mean to a 4 year old?  A big toy is perhaps a foot long? Maybe?  You wonder what they expect, although they are already processing the concept of limiting their expectations so as not to be disappointed.  So ‘big’ is relative, especially when compared to all the other toys that receive the same description.  He kept asking what I was doing now (or more specifically, what the CNC machine was doing now).  He was confused that even after a number of parts were cut, we were still making components for his dinosaur.  Again, you could see it was already exceeding any preconceived notions of scale.

With the pieces cut out, we traipsed back into the house, where the dinosaur was assembled.

That is when eyes got really wide.  Followed closely by a most impressive grin!

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All up, took at most an hour and a few sheets of MDF, and that was about it.  Sure beats those tiny 6″ long models made in China that keep appearing in pop-up shops in the various malls.  Nothing is better than a ‘serious’ dinosaur.  Especially one that redefines the concept of “big”.  Better than oxygen.

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Plans from MakeCNC

Episode 112 Sabretooth

Plans from MakeCNC

Episode 111 Nova Infinity Chuck and Jaw upgrade

Swiss Cheese

Slowly perfecting my processes, in this case for what is called a profile cut, where the object’s outer border is defined and the CNC router cuts the shape out.

I’ve been using a 1/8″ upcut solid carbide router bit – the 46100 from Toolstoday.com for the job so far, but knowing that it is not the correct router bit for the job.  What I should be using is something like the 46184 1/8″ solid carbide compression bit, or the 46180. (46237 and 46227 are also interesting bits, being 1/16″ diameter, which would be needed if doing nested work in 3mm MDF.)

Few reasons.

1. An upcut bit produces a lot of tearout in MDF.  While I can easily fix this with a quick sand of the top surface before removing the sheet, it would be preferable to avoid that step.

2. The upcut bit, especially at speed and with a large depth of cut, tries to lift the material being cut.  MDF is not a stiff structure, especially in a nesting situation which really turns the board to Swiss cheese.  It becomes almost impossible to stop the board being lifted, so I had to increase the number of passes from 2 to 5, and even then had a few lifting problems.

Not a fault of the router bit, I’m just using it as I don’t have another one of that diameter (or smaller) to work with 6mm thick boards in a nested layout, especially where I need grooves cut in the workpiece that are 5.9mm wide so they can slot together.

I’m cutting at 80mm/sec, and with about a 2mm depth of cut (DOC).  I know the CNC machine and the router bit can easily handle a lot more DOC, but my holddowns cannot keep up.  If I had a vacuum table, or even used a fair amount of double sided tape, that would be much less of an issue.

To stop the individual pieces being cut loose and walking into the cutter, wrecking them, I added tabs to each piece generally 2-3 per piece, 4mm wide and 1mm deep.  These are easily cut and sanded away at the end of the job.

It is important to ensure the cut goes all the way through in that final pass.  I have been using 0.5mm, but am thinking 1mm would work better.  Certainly, that means the router bit is cutting all the way through and partially out the other side, but that is why the tabletop has a sacrificial layer added.

What I made this time is the tropical fish (Angel Fish)……..

CNC-1 CNC-2 CNC-3and a stegosaurus!

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It is very addictive!

And just for a sense of scale, here are both projects photographed alongside a bottle of wine (not so easy to see sorry!)

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Now I just have 148 designs to go!

Plans from MakeCNC

Video Test

A very quick test of the new camera setup for the Torque CNC.  The idea is to have the camera able to get a good look at the scene, without interfering with primary operations.

The mount is very simple, and can be removed in moments.  I need to do a little more to really lock it down, but it is already close to being a really functional design.

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It includes a zoomable light so the camera isn’t struggling, especially with the higher frame rate.  It isn’t designed for really high speed work, but it can still slow down a cut sufficiently to see the chips fly!

The Polaroid XS100 really looks the part too.  I decided it would look a lot better without the dust extraction mount, so will come up with an alternative collection at some stage.

This isn’t cutting any specific design – it was very much just a short test of the camera setup

Surfing the curve

There is so much to learn with this CNC thing. It’s very cool. So much potential. The machine itself, the software, and the entire genre.

Oh, and we have progress on the name, I am pretty confident it will be officially tagged the Torque CNC 9060. The 9060 is the model, and refers to the working dimensions: 900x600mm.

Today I wanted to ensure a perfect working surface, so set the CNC up with the Amana RC2251 2+2 Spoilboard bit from toolstoday.com

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This is quite an incredible bit. 2 1/2″ diameter, and the 2+2 design is due to the two replaceable cutters (RC) that are on the sides, and the other two located underneath the cutter, performing a shaving action.

See MDF has a bit of a problem- when it is made, it is done with a lot of compression, producing a really clean, smooth top and bottom surface. But if that surface is removed, it becomes quite furry, with the MDF fibres sticking up all over the place. These second shaving cutters do just that- they shave these fibres, leaving a “real smooth shave”.

The finish of the resulting surface is superb- perfect for CNC work. For those tables using a vacuum surface, some draw the vacuum directly through the MDF, and to achieve that, the hard original outer surface also has to be removed, and again the finish achieved by the spoilboard bit gives that.

I used the surfacing passes to also check the CNC router out. This is a big cutter, so a good load test. I ran the machine with a 40% stepover (this is the amount of cutter that is cutting into the virgin material, in this case 1″, which is significant. I was only running a 0.2mm depth of cut, because the idea is to minimise how much of the spoilboard is lost each time it is planed flat. I also ran the machine at 200mm/sec. 12metres/min, which is positively hurtling along.

With the surface flat, and importantly, parallel with the overhead gantry, time to try another capability of the machine. 3D routing.

I’m using Aspire to generate the code, which is the premium software from Vectric. They have some 3D samples, so as a first step, I used one of those. In this case, a maple leaf.

Using the Amana Tool ZrN 3D carving bits from toolstoday.com the result is rather impressive.

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