Jun 2 2016

Aluminium Cutting and tips for cnc routers

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Aluminium Cutting and tips for cnc routers

Some hobbyists may ask if a CNC router can cut aluminum(Aluminium Cutting) since you most often see other users cutting wood or plastic. You can use your CNC router to cut aluminum if you know how to do it right. Aluminum (and other metals) are different to cut compared to wood or plastic. They have a smaller “sweet spot” for optimal cutting. If you leave the sweet spot your cutter will start breaking and wearing out faster and the surface finish will not be very good. Another thing to keep in mind is the “stickiness” factor (this applies to some other metals too). Aluminum wants to stick to your tool. It will do this to the point where it welds itself to your tool(tools). When sticky bits of aluminum have clung to your cutting edges your tool is not going to have much more life in it. Even though it is challenging you can cut aluminum on almost any CNC router. This article will give you a few tips to make sure you stay on track doing that job safe and proper.
While a CNC router can cut aluminum it is not the best tool for big parts, like vehicle parts. To cut successfully you need to do the job slowly. Just let your machine do its job and do not be in a rush. Cutting aluminum is not easy and will probably push your CNC router to its limits(Aluminium Cutting). Use a Feeds and Speeds calculator to optimize your settings so that you are not dodging the tip of your cutter that broke off and is flying across the room. Ideally you want to use a calculator that takes minimum RPM, CNC router cutter types, deflection, rubbing warning and chipping thinning into consideration. Your first problem will be recommended RPMs being too low. A CNC router cannot always go as slow as you want to go for cutting aluminum but there are ways to bump you’re the recommended RPM and fix this problem.

CNC router cutting aluminum ((Aluminium Cutting)

(Aluminium Cutting CNC router

The first tactic is to user cutters that are good at high speeds. The measurement to look for is Surface Speed which is high is carbide cutters. Cutters like HSS and Cobalt will be too slow so look for carbide TiAIN coated cutters. They cost a bit more but the improved results of your project will be worth it. Say you were using an HSS Endmill and the recommended RPM is 5877. Your CNC router’s spindle may have a minimum speed of 20,000 RPM (this is a very common minimum speed for routers). A TiAIN Carbide Endmill may have a recommended RPM of 16,897, putting it much closer to your machine’s minimum RPM. For aluminum try to get as close to 20,000 RPM as you can and you should be fine.
Another way to increase RPM is using small diameter cutters. The largest cutter you want to use should be ¼” but go smaller than that if you can. You will most rigid cutters to stop tool deflection from being a problem (this is where having tool deflection on your calculator becomes important). The smaller your cutter is the closer you can get it to 20,000 RPM. Be extra careful about clearing away chips. Recutting chips is an easy way to break a cutter. Be paranoid about this and do not just assume that your dust collection system is good enough without testing it for this first. It will be harder to get chips out as you cut deeper. Make more passes to cut down as far as you need to and you will open up shallower depths for better access. Lubricate your tools that that the chips will not stick to your cutting edges. The best way to do this is with a mister if you can set one up.
Now you need to think about avoiding tool rub. Going too slow with your federate can cause this to happen. Using your calculator should let you dodge this but be careful because the high speeds of your CNC router can result in tool rub happening easily. It can even start to happen while you are unaware that it is going on. If you cannot feed fast enough use fewer flutes. You should use a maximum of three flutes at once regardless. Using few flutes is good and is the reason 1 flute cutters are sold. There is a lot to remember when cutting aluminum but once you know what you are doing you should be able to use your CNC router for aluminum projects safely and accurately.


Mar 24 2016

CNC Routers vs CNC Milling

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CNC Routers vs CNC Milling

CNC Routers vs CNC Milling

CNC machines with a 3 Axis set-up are usually routers or mills. While both machines are similar in principle they are used for two very different purposes, resulting in them being constructed fairly differently. This article will give you a brief analysis on the difference between the two machines.

CNC Router vs CNC Milling

CNC Router and CNC milling

CNC routers are commonly used to cut soft materials like wood, foam and plastic. With the right know-how a CNC router can even cut aluminum and other soft metals. Because the materials being cut are soft CNC routers are built fairly lightly. A small CNC router can weigh several hundred pounds but that is very light compared to larger routers and mills. The soft materials cut on a CNC router tend to come in large sheets so CNC routers have big cutting surfaces but a small z-axis. Cut and jog rates tend to be high due to the large area that needs to be covered during the cutting process. For example, some routers are capable of jogging at 12 inches per second. On average a CNC router will cut four to eight times faster than a CNC mill. CNC routers can operate at 25,000 to 30,000 RPMs at high speed while a CNC mill will have a speed 3000 to 5000 RPMs when cutting quickly. The trade-off of a router is accuracy. Due to the high speeds a router cuts at there is not as much accuracy as you would get when using a mill. Usually soft materials do not need to be precisely cut to a 1/1000 of an inch so it should not raise any issues in most cases. CNC routers can be fit with a router or a spindle as a cutting tool.

CNC Routers vs CNC Milling

CNC router

CNC mills are beasts compared to routers. They are built to cut hard materials and that can mean anything from aluminum to titanium. CNC mills are often used to create (or mill) machine parts so they are incredibly accurate when cutting. The average mill is accurate down to 1/1000 of an inch, if not even more accurate than that. A CNC mill can cut with such accuracy because they are made with extremely hard materials, such as die cast iron, that will not flex under any load you put on them. This makes CNC mills many times heavier than CNC routers. A large CNC router can weigh upwards of 15,000 lbs. while a CNC mill that is just as big can weigh 90,000 lbs. Hard materials need to be cut at much slower speeds than soft materials so CNC mills do have a much slower jog speed than CNC routers. CNC mills use spindles like CNC routers can but they do not use routers since spindles work better than routers at lower RPMs. CNC mills can be used for routing but tend not to work as well as a dedicated CNC router. They also have a much larger z-axis than CNC routers because they are often used in conjunction with a rotary indexer. CNC mills are significantly more expensive than CNC routers of equal size and usually have a smaller cutting area than their similar sized CNC router counterparts as well. Any CNC mill with an area larger than 2×2 feet can easily cost tens of thousands of dollars. CNC mills can be built to handle different types of materials (horizontal, vertical, multi-axis, etc.) as opposed to a CNC router designed to handle sheet materials. CNC mill manufacturers often sell their machines with different spindle options depending on what kind of material you intend to mill.


Mar 17 2016

PCB Making with a Low End CNC Mill

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PCB Making with a Low End CNC Mill

Generally you have two options when you need to get your hands on a custom PCB. One is makes it yourself using etchant. This can be tricky to do since chemicals are messy, potentially toxic and can be difficult to acquire depending on where you live. Another is to pay a professional company to do the job for you. While this option is not terribly expensive it can take a few weeks for you PCB to get to you and no one wants to wait that long. Making the PCB yourself on a mill is a quick way to make the item yourself without messing with chemicals.

Making PCB with a CNC Mill

Making PCB with a CNC Mill

Like any special project, milling your own PCB has upsides and downsides. On the positive side of things this is a very fast project and you do not have to handle chemicals. The mill does the drilling so things should remain relatively error free and even if they do not all you have to buy are blank circuit boards, which are fairly cheap. Once you have your board made you can also make duplicates if you need more than one. However, you should also be aware of the project’s negative aspects before you decide to jump into it. The actual process of milling the board can take a while to complete, tying up your machine if you need it for other things. The project is also going to be very messy; expect to clean up a lot of pieces and copper clad fiberglass. Doing this work yourself will cause some wear to your bits and other tools and those things are expensive when they need replacing. Most of the negative aspects are things you would have to worry about anyway with any milling project so do not get too detracted by the potential downsides of this project.

Making PCBs with CNC Mill

Making PCBs with CNC Mill

This project will require you to have the same basic tools that you would use for a regular CNC milling project. A mill (obviously), CAD/CAM software and so on and so forth; additionally you will need the G-code for this particular project, a 30 degree V-shaped engraving bit and some carbide PCB drill bits (any random surplus bits should work fine). The V-shaped bit is going to be the trickiest thing that you are going to have to mess with. You are going to want very small and very clean lines to be etched while you are milling. A V-shaped bit is going to widen the cut it makes as you cut deeper. It may take a little trial and error before you find the ideal cutting depth to use with this project.
There are a few things that can go wrong while you work on this. If your V-shaped bit is too dull your cuts will be wider than you intended. You may also need to lower the Z height in order to cut at all with a dull bit. Using wide traces when designing your board can be a good safety net so that sloppy work does not result in too bad of a problem. Beyond that you just need to remember to follow basic rules of working with a CNC mill. Wear safety google or some other form of eye protection at all times, do not leave the room while the machine is running and all of that good stuff. This project is not terribly complicated compared to some of the other things you can do on a CNC mill so you should not run into too much difficulty.


Mar 10 2016

Cardboard Cutting with CNC machine

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Cardboard Cutting with CNC machine

At a glance you would not think that cutting cardboard would be a very challenging task. Cardboard is not a hard material like metal so how difficult can cutting it be, right? While cardboard is not the hardest material out there it is rigid and can be just as sturdy as any other man-made material. These days there are even companies that make furniture out of it. Now you could use a pair of scissors or a utility knife to cut the material but who wants to do manual work like that when there is a CNC machine option available. There are two major options for cutting it with a CNC machine, using a drag knife or a laser cutter.

CNC machine cardboard cutting

Cutting cardboard with cnc machine

Cardboard cuts differently from most other materials that you can work with on a CNC machine so average tools like bits do not get the job done. This is where the drag knife comes into play, being about to make the smooth cuts required to work with cardboard without wrecking the material. Before you do anything else, turn off the power to your spindle. You do not want your drag knife to spin; the knife must remain in a stationary position while it is making cuts (it is called a “drag” knife, not “spinning” knife, for a reason). Because the knife does not spin at all you will have to turn it yourself to realign the cutting edge when you want the cutter to move in a new direction. If you are used to working with bits or similar tools that can turn on their own be sure to remind yourself about the drag knifes limitations when you are programming your code. You are also going to need a way to hold the cardboard down very tightly but do not use a vacuum system. If a vacuum is used air will be pulled through the cardboard and the pressure will make cutting more difficult. Not every user will be adapting a CNC machine they already have for cutting cardboard, in which case you could purchase and use a paper cutter for this type of project. Most paper cutters are inexpensive but they tend to limit the size of cardboard you can work with and are often ineffective at cutting thicker cardboard.

CNC machine cardboard

Cutting Cardboard with cnc machine

Laser cutters are easier to cut cardboard with and are more effective than drag knives. Adjusting the cutting power on a laser is simple; all you have to do is change the power settings to alter the intensity of the laser whereas with drag knives you would have to buy multiple knives of various sizes or fine tune your machine to make small cuts very carefully. Laser cutters also leave a nice, crisp edge along the cuts they make. Additionally, since lasers do not put any physical pressure on your material you do not need the keep the material held down as tightly as you do when using a drag knife. While lasers perform much better the big downside is their cost. Be prepared for a hefty price tag; if you do not need a laser cutter long term or if you want to test one out to make sure you like the results try renting one before you commit to buying a pricey CNC machine.
There are other methods to cutting cardboard with CNC machine besides using a drag knife or laser cutter but many of the other methods do not work as well, are only suited for thin cardboard and are less common than using either of these techniques. While your budget may limit what method you can use for the job you should still be able to get your task accomplished as long as you know what you are doing and have a little creativity.


Mar 3 2016

Leather CNC and Rubber Cutting

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Leather CNC and Rubber Cutting

Many of the materials that you will find yourself working with on a CNC machine can be cut using standard techniques. When you boil it down to the basics cutting different materials like wood, metal and plastic all use techniques that are pretty similar during the cutting process. Some of the less common materials that you might work with have different properties from the more frequently used materials and therefore require you to do your work in less standardized ways. Two types of materials that you need to cut differently are leather and rubber.

CNC leather cutting

Leather cutting

Leather is difficult to work with because of how it cuts differently compared to more common materials; you cannot just lay the leather down and cut it with a bit or you will ruin the material and your project will not look presentable. Hobbyists who already have a CNC machine can equip it with a drag knife in order to cut leather but there are a few things to keep in mind while using a drag knife. When getting your machine ready turn off the power to your spindle or router. The drag knife should never spin while it is cutting. Because the drag knife does not spin at all on its own you will have to manually realign its cutting edge when you want it to move in a new direction. Keep in mind that it can only move in the direction that the cutting edge is facing when you are programming your tool paths. In addition to a more specialized tool you will also need a very strong way to hold the material down. Leather needs to be held down as tightly as you can manage when you cut it. When you are selecting a hold-down method you cannot choose a vacuum. If a vacuum is used the pressure from the suction will go through the leather, making it almost impossible to cut. While a drag knife does work it is more suited for working with thin leather but it is not your only option. For any leather (thick leather especially) a laser cutter works very well. Because the laser is not physically cutting through the material you do not have to worry about how the leather will cut. Additionally, there will be no frayed edges and the leather does not require as strong of a hold-down method since the laser does not put any physical pressure on the material. Overall a laser cutter is better for cutting leather but many hobbyists do not have access to a laser cutter.

leather cut cnc

Leather cut

Rubber is a bit more challenging than leather. While rubber can be cut there is not necessarily an “easy” way to do it. First off, do not even try to cut rubber if you are using a laser cutter or a plasma cutter. It will catch fire. When working with rubber you are going to have to mill it. The key to cutting rubber is to freeze it so that it become more solid and easy to work with. To what extent you want to freeze it can depend on the type of rubber you are working with. In most cases freezing it with dry ice will work (-80° C). You can also freeze it with liquid nitrogen (-320.8° C) but that might be overkill. Once the material is frozen you are going to have to machine it very quickly before it can heat back up (especially if you are using dry ice). You will also need a tool that is extremely sharp. This can be a challenging process so do not be surprised if you cannot do it perfectly the first time. Rubber can be cut just as easily as any other material with a water jet cutter but most people will not have access to one of those due to their price. You are more likely to go with the freezing-then-cutting method.