Steve Bush January 27, 2021
Not long ago, I bought myself a small "1810 pro" cnc router to make pcb.
This machine is fun to assemble-like a 3D printer kit-and it can indeed cut single-sided PCBs. If you can accept wires instead of plated through holes, you can also use a double-sided PCB.
In addition, the decorative parts can be easily made of wood or plastic, up to a thickness of up to 45 mm (one shallow cut at a time).
Providing accuracy is not essential. Simple functional items such as boxes can be manufactured by cutting wood and plastic parts and then assembling them.
Due to slack, insufficient rigidity and low spindle power, the production of precise functional parts and cutting aluminum is beyond its scope.
However, like many people before, I would like to try to modify the small cnc to reduce the slack, increase the stiffness and increase the power to reach the level of cutting aluminum, and may have an accuracy of 0.2 mm and a softer material.
A short note about aluminum-the standard 1050 material is very sticky during processing and can easily clog the tool. I found that 6082 aluminum is only slightly more expensive and much less viscous.
After reviewing a few options, I outlined this (left) idea in Design Spark Mechanical to improve the x-axis (lateral movement) and z-axis (up and down) and drill holes using standard parts and hand-cut 5 mm flat aluminum plates , May provide 3D printing support for the stepper motor driving the z-axis (the top cube in the figure).
It reduces bouncing and bending by replacing the unsupported guide rods with supported guide rails, instead of rectangular (MGNxx) rails and trucks mounted on a single 80x20mm aluminum extrusion, to replace the two 20 x in the original design. 20mm parts.
Supported cylindrical (SBR10 or SBR12) guide rods will be cheaper and may be just as good, but they are bulky and can be installed without further cantilever spindle motors. If this design can be made to work, it will be about 10 mm less than the standard cantilever, and if a small anti-backlash nut can be found, the cantilever will be lowered further.
There will definitely be some slack, because it currently comes from two places-between the cheep-n-cheerful LMxxUU bearing and the cylindrical guide rod, and the outside of the bearing between them and their plastic housing. Both clearances are designed, and fingers are crossed, the cheap MGN type support slider will have less slack than the very cheap LMxxUU bearing and its rod.
Now that I understand some knowledge about cutting, I realized that the softness of pushing the tool into the material is limited, because under a certain force, the edge of the tool no longer cuts, but rubs without cutting (this is obviously Will quickly dull the tool) also).
The existing NEMA 17-axis drive stepper motors are still in use, as are the T8x4 lead screws. Although this limits the available force to push the tool in any particular direction, many people seem to be taking advantage of this standard setting.
The spindle motor is attracting attention.
Installed is a typical 24V 6,000rpm brushed DC "775" size motor, which consumes about 4A under load (~100W, curse no suppression components).
This is 42 mm in diameter, and many people replace them with 55 mm (or similar) diameter 300, 400, or 500W motors-increasing the motor mass to about 1 kg and extending the terrible cantilever by 6.5 mm. No wonder the x-axis stiffness becomes an issue. The brushed version with speed control power supply only costs about £80, and many will reach 12,000 rpm. More cash will give you a brushless one.
Just recently, Sainsmart launched a higher current 20,000rpm 24V 775 for only about 30 pounds-very cost-effective. However, reading reviews has some luck factors-as with all 775s-whether yours will vibrate. I have to say that most of the comments are positive.
I chose a different option: Longdaio produces the LD42WS-250W, which is a 42mm diameter 250W 24V 12,000rpm three-phase brushless spindle motor-so it can be replaced without an additional cantilever. It's more expensive-80 pounds for the motor alone-but it looks more like a professional router spindle, and has a stiffer 8mm spindle instead of the 5mm or ~55mm type in the 775 motor 1/ 4 inches. Please note that in an earlier version of this blog, I wrote that the ER11 chuck housing was machined to the end of the motor, but now that I have it, it seems to be pressed on the 8mm shaft. The motor weight is 683 grams, if you choose to use it, the aluminum bracket (with 57 grams bolts) will add 417 grams to 1.1 kg – well, the bracket is so thick, I want to know that it uses the same as a 55 mm motor Extrusion, but a smaller hole was drilled in it?
Browsing through various parts of the Internet, this motor seems to be the most popular with Russian manufacturers, but not in Europe or the United States.
Overall, the budget is still low, but there is still some room for expenditure, because a machine can make light cuts from aluminum, ready to use out of the box, with any dignity (except maybe 1310, see Part 2), It will cost more than a thousand pounds. This situation is different from a 3D printer. In this case, a machine like Ender 3 will provide you with 95% of the quality and capabilities of a £1,000 machine at a price of 230 pounds, and you can get a score for less than 400 pounds. Prusa Mini is 99%.
For more information on the different low-end cnc options, see Part 2 (tomorrow).
At the same time, there are many excellent videos about small cncs on YouTube. I especially recommend Minh’s man Cave, a person who started using cheap cnc about a year ago, used it to improve it himself, and then used the improved one to build a bigger and better cnc, and then used it to improve himself, etc. Wait-all of these require only basic additional tools. He finally got a machine that could easily cut aluminum and pierce steel.
Tagged as: 3D printing computer controlled machinery
"My advice to YouTube Engineering Entertainment is the post-apocalyptic inventor and his maintenance marathon,"
Surprisingly, I watched his channel but was not attracted to watch it. Too many mechanical things? Not enough creative curses, like AvE? 😉 Between EEVblog, Great Scott, Andreas Spiess and some ElectroBoom (I like his series on spark gap high voltage oscillators), I seem to spend a lot of time on youtube. Join some general science channels, such as being smarter every day, I need to consider which channels I want to quit. To be honest, most of them did a good job, and if I didn't look at them, I would feel sad.
ps I am replying to a blog and not a specific post because the "reply" button is missing from your post. Software failure? I am using Firefox.
In the morning, Mr. Kurt, maybe I committed a crime against the Internet and deleted the reply button permission? I also like the great Scott, if it's just or neatly handwritten 🙂 Have you seen the channel represented by Marco. He repaired old precision instruments-he collected a series of advanced voltage references. (But note that he also built a milling machine-but accurate to micrometers). This guy really knows the source of his errors, including mechanical and electrical. I'm trying to control my YouTube habits-it's easy to indulge in it when locked, and find that the second half of each night disappears...
I'm pretty sure I've watched Marco Reps' video... German accent? I do remember some work on large CNC machine tools. It's nice to see someone considering design issues such as error sources (this is an old aerospace simulator). Some youtubers are good at trying to cover a topic, but tend to obscure all the ways you might get into trouble. It seems to be a way to get people enthusiastic, but when they encounter unexpected obstacles, they end up feeling frustrated. Although I do spend more time on youtube, I spend less time on TV. ...However, it can't completely make up for YouTube's time! 🙂
Wow... a 250W motor? ! As someone who knows nothing about these things, this seems to be enough to get the job done quickly or cause a lot of trouble. Maybe both? ? 🙂
Good morning Mr. Kurt, very happy to hear from you. Such a small thing does seem to be a lot, but from another perspective, the 250W domestic wired electric drill is already history, and now it is generally between 550-800W. In addition, 250W is transmitted at high speed on the cnc, so the torque, I guess, is the torque that transmits force to the machine, which is lower than that of a low-speed motor. – Now, I can’t think of how high speed can be transformed into mechanical force – Any ideas?
"How does speed translate into force?".. Hmm...For the tool, higher speed means you can remove material faster, so it might mean more force? I think it depends on the feed rate. Of course, I only know what I learned from youtube, so don't believe me! Speaking of which... this old Tony just put a long video on his cobblestone CNC machine! ! 🙂
Snap-I saw this old Tony's newest Mr. Coulter this morning. He did everything he did very well, plus a little wit. I believe you introduced his YouTube channel to me first-thank you. In terms of tools, I am in a similar position to you, because almost all the work I have done so far is sculpting-only one terrible wiring session-no tool damage 🙂 My simple understanding is that in a limited spindle Torque and the need for each passing blade to cut at least the minimum horizontal depth to avoid friction, the only other variable is to limit the vertical depth of the horizontal slices that are removed. Then the power of the stepper motor will be, I guess, related to how many cuts are made in a given time-I also guess that the material where the response to speed is non-linear to push a given blade into it. Oops, this is a whole new world, and I hope to stand on the shoulders of giants again. Do some interesting things during the lockdown! !
Besides enjoying This Old Tony, I also waste time watching youtuber AvE. He started making videos on Arduinos, but then turned to tool reviews and processing (and other manufacturing topics) videos. He has a video about processing copper hammerheads, which illustrates some of the problems encountered in processing this soft, malleable material. Just search for "making a copper swing press" on YouTube. fwiw, get ready for some "rich and colorful" languages! That is, language is more suitable for workshops than classrooms.
Good morning, Mr. Kurt. I also watch AvE, although I don't like the gimmick of opening a package with a chainsaw-I think sometimes this behavior is blurred by men. But it's good, obviously knowledgeable. I have never seen a copper hammer, and I can search. My suggestion for youtube engineering entertainment is Post Apocalyptic Inventor and his maintenance marathon. In addition, he also created some interesting power electronic devices.
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