Machsupport Forum
General CNC Chat => Show"N"Tell ( Your Machines) => Topic started by: xtjoliverx on March 01, 2015, 11:44:47 PM
-
Hello, just thought Id show the community what brought me to this forum. Im currently working on my first CNC machine. Im building a CNC plasma table that I hope will also be able to mill aluminum and maybe even take some light cuts in steel. Instead of making twenty posts to show my build log, I will just post a link to my Facebook album that contains all of the pics.
https://www.facebook.com/media/set/?set=a.524830614326022.1073741829.100003972633149&type=3
-
If you try to view the link on your phone, after clicking the link hit your settings button and request the desktop site. Sorry I just now noticed it did that.
-
This is only my first machine, and although the first one isnt done yet I am open to any suggestions, improvements, crticism, etc. As soon as this one is up and running Im starting my next one. This being my first machine I knew going in that I would find improvements and different ways of doing things. Its already much different then the solidworks model I designed. Also, I will not be building any of my next machines from a pile of scrap. The owner of the place I work wanted to scrap it all. I was just showing him the value and use in it, and that it could be put to good use. So i offered to cut and clean it all up in my time for some of it. Thanks again for any suggestion and criticism ahead of time.
-
Good on you! I hate to waste stuff too. Not sure what your using as a motion device but electrical noise can be a huge problem with plasma cutters. I don't like to have 5v outside of the cabinet of any machine. Far less likely to have issues with 24v. Have a look at this topic and be sure to read all the manuals you can.
http://www.machsupport.com/forum/index.php/topic,25616.0.html
You have likely done most of this already but this is from our FAQs page. I think the whole page is well worth reading.
Where do I start? Are there steps?
Yes! For anybody just beginning with CNC, the following steps are absolutely essential. Even pros with many years of experience may be able to pick up a few pointers. All machine controls are different, and even a person who has run, worked on, built, or installed CNCs for many years using any particular control will experience a learning curve when using a different control. Mach3/Mach4 is quite capable of controlling a machine, but there will be differences between it and any other controller. Also, the hardware used in a CNC can have a dramatic effect on how the software and complete system operate. The bottom line: each system will behave slightly differently. The control (no matter whose) is not capable of understanding the operator; therefore the operator/designer must be capable of understanding the control and creating their system.
1) Read the manuals. Even the most seasoned pro will often reference the manuals when they have a question. Reading the “Mach3Mill Install and Config Guide” in its entirety, and making notes of any questions it may prompt, is a great first step. It is important to fully understand how the software operates to create and use the system that is created. The knowledge the manual provides can reduce the chance of expensive or time consuming rework.
2) Watch the tutorial videos. These are fairly short and loaded with information. They can be found on the Tutorial Videos page of the website.
3) Establish requirements and write them down. List the requirements the machine must achieve, such as the tolerance it must hold, repeatability, rapid speeds, feed rates, acceleration, coolant, power source, etc.
4) Gather information. Collecting any and all relevant documentation available from the outset of the project. This includes any manuals or data sheets for the machine and/or the components. Components or machines with poor documentation may require careful consideration.
5) Make an I/O map. Using a spreadsheet to list all of the I/O (inputs and outputs) and document which pin of which device they will be wired, can save effort with both configuring Mach3/Mach4 and troubleshooting any issues. This will likely be used for the life of the machine.
6) Draw diagrams. Diagrams for the electrical, pneumatic, hydraulic, coolant, etc. systems can be important when troubleshooting a machine. If the machine is a retrofit and did not come with any diagrams, it may be well worth the time to create them.
7) Generate a parts list. Document what parts are needed, where to acquire them, their cost, part numbers, etc.
8 ) Review, edit, and update. At this stage, there should be a solid understanding of what type of machine is desired, what parts are necessary to produce it, and a pretty good idea of how everything ties together. Chances are that along the way, required adjustments have been made, so now is the best time to update the documents accordingly to reflect these changes.
9) Gather components. It should now be possible to make educated decisions about the components required to build the machine and feel confident they will give the desired results. If this is not the case, it is time to backtrack as far as necessary in the process to reach that comfort level before actually ordering any parts.
10) Bench test. Once the components are gathered, it is time to assemble and test them. It is advisable to initially perform this process on a bench (desk, table, work shop bench). Testing before permanently installing the hardware and routing the wires in the machine will often save a lot of time, trouble, and frustration. It is not unusual for things to fail to work exactly as expected with a new setup.
11) Assemble and test. After the hardware has been bench tested, it is time to install it on the machine. It is the responsibility of the builder to make sure that assembly is done correctly in order for the machine to meet the specifications that were set. Care should be taken to ensure that everything is done properly the first time. If questions arise, they should be researched and addressed before continuing otherwise the machine may not perform as expected.
12) Purchase Mach3/Mach4 & Enjoy! If everything has been done correctly up to this point, the only thing left to do is purchase a license for the software. If everything has not been done correctly, the decision must be made as to whether or not the results are acceptable or if things need to be adjusted.
Brett
-
Yes your right, I have done all of this. But, I wish I would have found all this info in one place before I started this project. This is good info that should be stickied. I am worried about the noise though. Any recommendations?
-
Our FAQs page and the members docs boards are some of the best (but often overlooked) resources.
http://www.machsupport.com/help-learning/f-a-q/
http://www.machsupport.com/forum/index.php/board,78.0.html
Just read and follow the information at the link in my last reply. That should get you off on the right track and give you a fair chance at avoiding noise issues all together. You should probably browse the forum to see issues others have had and how they solved them.
Brett
-
Thanks for the info. I tried looking into the opto 22 converters but dont really know what Im lookjng for, think you ciuld give me a nudge in the right direction? Also, have you or anyone wlse ever used a wire mesh shielding sleeve with any success? According to wikipedia, this stuff should act just like a Faraday cage. From what I read in your links, grounding these sleeves should help even more. I have shielded wire i am going to use, but if that stuff is worth it ill use that as well, and maybe one of these optically isolated converters. Think that will be enough to eliminate noise?
-
I have used these http://www.opto22.com/site/pr_selector.aspx?cid=4&qs=1003 (http://www.opto22.com/site/pr_selector.aspx?cid=4&qs=1003) The G4 single channel has a big selection. They have all sorts of racks for them. The ones that have a separate terminal for each relay pin are the most versatile but require the most wiring. You will have to decide which modules and racks would suit you best.......... if you decide to go that route. Probably the easiest and cleanest way to get 24V IO would be to use an external motion device with the optos built in. CSLabs and Vital systems offer those. Either way (external motion device with 24V IO or optos of some kind) is going to cost more. Robust solutions almost always do though. The higher price of the external motion devices offering 24V IO is usually a wash when you consider the expense of rolling your own. I have gotten good results with both. Any time I didn't use one or the other I wished I had and made the necessary changes so I could.
Good shielded cable has the wire mesh sleeve under the outer sheath or at least somewhere that is covered (sometimes several layers deep)............... which is what you want. Heat shrinking the ends is a good idea too. You dont want to give the noise a way to easily follow your wires. You want to make the possibility of that as low as possible. Shielded cables give the best of the 2 features you want. Make it hard for noise to get to your control cables to begin with but give any that does get through the insulation (sheath) an easy path to ground. External braided shield would make more of an antenna (which is not what you want). It would give the noise an easy path to ground though but still best to avoid it I think. Igus makes great cables designed for all levels of noise immunity and they sell everything they offer by the foot if you want it that way. Again, it isn't cheap but it does work........................ if used/installed correctly. The used/installed correctly is the magic dust in the whole noise immunity recipe. You can take the best parts known to man and make a mess or the most inferior parts and make woks of art. Planing, planing and more planing should be the first line of defense. Good patrs is cheap insurance IMO.
Brett
-
Once again, thanks for the info. I have already decided to build my own enclosure. I already had the sheet metal ordered at work, and I think it will probably be delivered early this week. However, after reading the articles you suggested, looked at the products youve recommended, and considered your advice, I am going to rethink the design. Since I am the manufacturer, middleman, and customer I can build an enclosure that suits me while using better materials. Since I am the customer I am not worried about keeping costs down and will be using 14 gauge sheet metal. If youve seen the pictures you can probably tell I am not worried about keeping weight down, except when it comes to the gantry. What about putting that wire mesh sleeving over the plasma torch lead? You mentioned that stuff would work like an antennea? Think it would help to keep some noise from escaping the lead?
-
I am also look for criticism on the design. I would like other viewpoints on things people would change, etc. This is my first machine, but there will be more. I knew coming into this project that it would be a learning experience, and I plan to use the experience, and knowlege in future machines. If anyone of you were building this machine what would have have done differently, and why?
I probably should have mentioned some info you cant get from the pics before now oops:
Mach 3
Sheetcam
1232oz/in nema 34 motors (x axis is slaved there will be 2 motors moving that gantry)
proma THC
Hypertherm powermax 65 plasma
-
Several things come to mind IF you are building a plasma table.
1. You have severely overbuilt the gantry making it very heavy with lots of inertia weight. Plasma gantryies need to be as LIGHT/Stiff as possible as themachine needs to move at high velocity AND accelleration values .
2. I do not see any gear reduction on the table axis. To get the high acceleration values you NEED torque to get the gantry moving AND to stop the gantry without loss of steps.
3. The PromaTHC is NOT the best of solutions for a THC. You would want a system that CONTROLS the Z axis independantly from MACH3. Let Mach drive the XY and the THC drive the Z. Letting Mach3 control the THC is always a compromise at best.
Just a thought, (;-) TP
-
Hey, thanks for the input. And, those were exactly my worries as well. I know that gantry is heavy, and I am planning on redesigning it. I was thinking of maybe taking the back square tubes off and putting in a brace or two somehow. I also am toying with designs to cut out of the gantry side plates for weight reduction.i was also thinking about just cutting the square tubing in half and using that instead of the C channel. The tubing wall is only about 1/16" thick. The channel is much heavier. Actually I think thats what ill do, those couple things should make a huge difference. As for gear reduction, I have been worrying about that, but I hope with some redesigning I can shed enough weight to get away without it. That would be a pita. The proma thc is my mistake. I did research before I bought it. But, after buying it, thats when I started coming across all the people warning about it. There are success stories so Im hoping I can get it to work. If not then I have been looking at some options at a company called CANDCNC. Have you or anyone have any experience with them?
I guess it might be helpful if I let all of you know that i dont plan on cutting thin materials often. And when I do the thinnest I will ever need to cut will be 14 guage.
-
Ok, with the advice of BR549 and Chaoticone I fiund some areas that need addressed. First, is the noise. I have added some further protwction against that and will be implementing that when I get to that point in the build. I have to admit, I knew it was an issue, but chaoticone made it clear that its a bigger issue then I originally thought. He also stressed and restressed the importance of proper planning and research. I have been designing and researching for about two years before I started actually building. I am far from being a knowledgable source on the topic, but I think in that two years Ive learned enough to get my feet wet, and continue my learning experience hands on. BR549 opened my eyes to the weight of the gantry, which made me rethink the design on that. So far, I have taken( in design) the weight from about 200 lbs down to 120ish lbs. I am in the process of alternate gantry plates from thinner material. Those 3/8" plates weigh about 28lbs each. So that is definately another area I could shed some weight. As soon as I get time that is my next step in the build. Also pointed out was gear reduction, and have researched and calculated a 3:1 reduction would suit my needs. I have already started looking around for the 3" DP 20 Pa 20 pitch gears I will need. Does anyone know of a good source for these gears? All I can seem to find are very expensive prices for a simple little spur gear. And the THC, was also mentioned as a problem area. I am hoping it will suit my needs, I will be cutting thicker plate most of the time. According to Hypertherms tables the fastest I will ever need to cut at is 150ipm. Im hoping that proma can keep up. If not, then I will cross that bridge when I get there.
-
Sorry, I forgot to add at the end of the last post, asking if anyone has any other suggestions. I should have been asking this from the start. But, it will still be easier to address changes now, rather then wait until the end.
-
Gear reduction only increases torque if you're prepared/able to accept the proportional loss of speed. Even then, with steppers, I'd argue you get better acceleration with direct drive. All the (stepper) plasma tables I've built have been direct drive - never had an issue and run 15m/min at 0.5+G no probs.
What I WOULD do is consider nema23's rather than 34's - you'll likely get better performance.
-
Could you elaborate a little please? How would nema 23s give me better performance? And thanks alot for your input on the direct drive. What size gearing were you using? My gears are 20 pitch 20 pa and 1" pd.
-
Hi,
i put the "iknoweverythingbettermodusON"
How would nema 23s give me better performance? And thanks alot for your input on the direct drive. What size gearing were you using? My gears are
if you whant speed an torque there is now other way than to use servos.
ok "iknoweverythingbettermodusOFF"
Thomas
-
I did not use servos because of cost. I would rather have torque than speed. Like I mentioned in a previous post, the fastest I will ever have to cut is about 150 (ish)ipm. This machine is not going to be a full out production machine so I dont need the fastest rapids etc. But, when I am cutting and change direction at 150ipm I dont want to stall or lose steps. That is why i am totally starting from square one on the gantry. The motors are not in yet. But, I have them hooked up at home to get everything working. When I am jogging it with the pendant and change direction very quickly I can hear the motor losing steps. I dont think i will know until I get them mounted on the machine and try it with weight on them. I might even have the speeds and acceleration set wrong. My plans are to (re)build the gantry as light as possible. And hook everything up and see what happens. Does anyone have any suggestions other than what I just mentioned? Is there a way to measure or test tis before hand?
-
Torque is a means to an end. What you NEED is the torque that gives you the speed to match your cut charts and the torque that gives you the acceleration to maintain that speed as much as is possible.
23's vs 34's: Have a search around there's a lot been said on this but briefly - bigger is not always better.
Gearing: I used direct 15 tooth mod1.
Ian
-
So, I started the gantry weight reduction phase. Unfortunately I forgot to take some pics before I left. I'm going to be working on it some more on Sunday. Ill take some pics then. I should have more to show by then. I eliminated the two steel channels that the rails were mounted to. I drilled and bolted them to the square tubes that were that the rear part of the original design. I found some 3/16 plate I might be able to use for the gantry plates, instead of the current 3/8" plates as well. I think that might be enough. Any input on this from anyone? Think that will be light enough for two 1232 oz. In. Steppers to move around? Stirling, could you nudge me in the right direction with the 23 vs 34 topic? Ive searched but cant seem to find anything on this forum comparing the two.
-
Think that will be light enough for two 1232 oz. In. Steppers to move around? Stirling, could you nudge me in the right direction with the 23 vs 34 topic? Ive searched but cant seem to find anything on this forum comparing the two.
GENERALLY 34's have higher inductance. Therefore to realize their potential in a CNC environment you need BIG voltage drivers and power supplies. GENERALLY 34's have higher mass rotors meaning more power is used just to accelerate the motor's own rotor mass. Post your motor, drive and power supply specs and we can take a quick stab at it if you like. Curiously, I thought this was pretty well known, certainly amongst the regulars here. I'm a tad surprised no-one's stepped up.
-
Ok, and thank you for the help. Before I post the info, I just want to mention that I purchased them from Longs Motor off of ebay. It was a 4 axis Nema 34 kit including the motors, drivers, power supplies, and Breakout board. Also, note that the drawing of the motor has been converted to inches. I have a bigger version of this saved and will gladly send it to anyone that would like it. It was a big time saver when I was designing my machine.
Motor(s):
http://www.longs-motor.com/
Part No.: 34HS1456
Frame Size: NEMA34
Step Angle: 1.8 degree
Voltage: 3.08V
Current: 5.6A/phase
Resistance: 0.55 Ohm/phase
Inductance: 5.5 mH/phase
Holding torque: 8.4N.m 1232oz.in
Rotor inertia: 2700g-cm2
Number of wire leads: 4
Weight: 3.8 kg
Length: 118mm
The stepper motor is single shaft, the diameter of axle is 14mm,and the length of shaft is 37mm with 25mm length flat.
Drivers:
http://www.longs-motor.com/
DM860A
Details
Features:
l High performance, low price
l Average current control, 2-phase sinusoidal output current drive
l Supply voltage from 24VDC to 80VDC
l Opto-isolated signal I/O
l Overvoltage, under voltage, overcorrect, phase short circuit protection
l 14 channels subdivision and automatic idle-current reduction
l 8 channels output phase current setting
l Offline command input terminal
l Motor torque is related with speed, but not related with step/revolution
l High start speed
l High hording torque under high speed
Electrical specification:
Input voltage
24-80VDC
Input current
＜ 6A
Output current
2.8A～7.8A
Consumption
Consumption：80W； Internal Insurance：10A
Temperature
Working Temperature -10～45℃；
Stocking temperature -40℃～70℃
Humidity
Not condensation, no water droplets
gas
Prohibition of combustible gases and conductive dust
weight
500G
I have the dip switches set up as such:
Current: 5.7A peak 4A RMS
Pulses per Revolution: 2000
Power Supply:
The only info I could find is the power output is 350 Watts 60 volts/5.83A
-
Nema 34 motor size converted to inches.
-
Unusually for a kit, that looks to be not too badly matched so maybe you'll be fine - only one way to find out. Still think at the very least though they're massive overkill. I'll be interested to see when you're done, what accel and speeds you can get.
Ian
-
I was hoping that myself. I hope to also attach a spindle to this machine and route wood as well. That and I knew that my gantry was going to be heavier then most, judging by the materials I had available. Also, do you think I have the driver dip switches set properly? I think I do but, a little reassurance would help calm my nerves a little bit. Thanks again to everyone answering my new guy questions.
-
For sizing motors I have used tools (I think it was an actual program) similar to this before but can't remember the name. http://www.orientalmotor.com/support/motor-sizing.html (http://www.orientalmotor.com/support/motor-sizing.html) I would think the one at the link would be pretty good but I am guessing it will give a part number for motors they offer instead of specs. (which could vary a lot from others even if they are the same size, sometimes even from the same manufacturer). Each motor will have its own specs. (torque Vs speed curve, holding torque, etc.).
Brett
-
Also, do you think I have the driver dip switches set properly? I think I do but, a little reassurance would help calm my nerves a little bit.
That - as they say - is a good question. Depends on what you read and who you believe. This is MY understanding. Others may disagree.
Motors are usually spec'd in RMS. So in your case 5.6A. (if you can actually confirm that's RMS then that would be good).
IF you're FULL stepping then peak = RMS. But you're (quite rightly) microstepping so you're tending towards sinusoidal. A pure sine wave would mean to get 5.6A RMS you'd need to set 1.414*5.6 = 8 peak.
-
Chaoticone- That is an awesome calculator. I am definitely bookmarking that tool for future reference. Thanks alot. according to that tool I should be alright when it comes to the motors.
Stirling- I have emailed longs motor and asked about the rated current, and if it is RMS or peak current thats listed. My driver allows me to go up to 7.8A peak / 5.6A RMS. But, that would mean I would need bigger power supplies, as they are only rated at 5.6A. I emailed longs motors and asked about the specs on it. They do not have this model on their website.
-
Stirling- I have emailed longs motor and asked about the rated current, and if it is RMS or peak current thats listed. My driver allows me to go up to 7.8A peak / 5.6A RMS. But, that would mean I would need bigger power supplies, as they are only rated at 5.6A. I emailed longs motors and asked about the specs on it. They do not have this model on their website.
Leave your drives at 5.7A peak for now and see what happens with what you have. Your supplies should be fine because chopper drives will only draw 2/3 of the current from the supply that they're set to deliver to the motors.
-
Ok stirling, I will do that. I havnt had much time lately to work on it. Between a full time job, being a full time studenand house shopping with my wife, theres been little free time. But, I have the sheet metal for the enclosure, and the 3/16" plate for the new lighter gantry. I did find the time to start cutting it apart. This is why I only had everything tacked together. I eliminated the channels and now have the rails mounted to the much lighter square tubing. I figure changing the gantry plates from 3/8" to 3/16" will shed quite a bit as well. All the rest will be aluminum as far as the Y axis and z axis, so that shouldnt add too much weight. Im hoping to find some time throughout the week and this weekend to get some work done on it.
-
Just thought I would stop in and give an update. Ive uploaded more pictures to the build album. Ive got the gantry back together and am now going to start building the Y axis plate. I think I might be able to do that tonight. The house shopping is done, so Im trying to get as much done as I can before settlement and its time to move in. I cant wait to tinker around in the garage. I managed to find a house with a two car, 3 story garage. That should be enough room to house future projects.
-
Just wanted to give everyone an update. I am under power now and starting to test it out. I was messing with it a little bit last night and realized I didn't have something set right with the slaving of the A axis to the X axis. I'm sure its something simple, I just ran out of time. Its starting to get more exciting the closer it gets to being completed. I also have been thinking about an upgrade I might want to make down the road. Has anyone had any experience with the hybrid closed loop steppers that are on eBay? I'm confused as to how they communicate to mach 3. Or is it a self contained system outside of mach?