[kn6za]

\r\n \r\n Sweet!
\n
\nAndrew\r\n \r\n

[pippin88]

\r\n \r\n Is that laser cut steel?
\n
\nLooks very nice so far\r\n \r\n

[stef110]

\r\n \r\n yes 8mm laser cutted steel, with 60x30mm steel bars on top. Everything now needs to be welded after that it will be stress relived and then all the mounting surfaces will be milled.
\n
\nstef\r\n \r\n

[NIC 77]

\r\n \r\n Your workmanship is top notch. Any factory would be proud of a product that looks like that.
\r\n
\r\nHave you already done all of the performance math for speed, acceleration, available cutting force?
\r\n
\r\nI\'m working on a spreadsheet for my own build. To try and determine the best pitch of ballscrew to use for the motors I have, and to account for possible future upgrades, including the effects of ballscrew and motor inertia. I\'ve already been playing with this for rack and pinion. I\'m curious if anyone else has done this that I can compare notes with.\r\n \r\n

[RotarySMP]

\r\n \r\n Great start to the show. Subscribed and getting popcorn
\nMark\r\n \r\n

[stef110]

\r\n \r\n Small update nothing big. Machined the steel strips that will hold the motor and end bearing. Also made two aloy strips that hold everything together so makes it easier to weld.
\r\nThere is no math behind this machine, just looking to other machines and looking what feels right. I am still thinking what to do with the motors, using closed loop steppers or using servo\'s.
\r\nI think closed loop steppers are good enough but with servo\'s i can get higher speeds if i want. How do you guys think about closed loop steppers vs servo\'s.
\r\n
\r\n
\r\nused a nema38 8nm closed loop stepper from my current cnc to test fit.
\r\n
\r\n
\r\n
\r\nStef\r\n \r\n

[NIC 77]

\r\n \r\n

\r\n

\r\n

\r\n

\r\n \r\n \r\n

I think closed loop steppers are good enough but with servo\'s i can get higher speeds if i want. How do you guys think about closed loop steppers vs servo\'s.

\r\n \r\n

\r\n

\r\n

It really depends on what you want to accomplish. You have fairly small travels, so what speeds do you want to achieve? You will be limited by the critical speed of your longest screw for maximum speed. It doesn\'t really matter what kind of motor you have beyond that. What speed do you want?
\r\n
\r\nAlso, acceleration is an issue that will affect your performance, and your machine does not look light. Do you want a speed demon, or what are you happy with? Are there two screws for the bottom tier? I see holes where two screws could go....but that would put those screws out in the open? And you have put alot of work into protecting the top screw from debris, so I don\'t know what you have planned.......
\r\n
\r\nWhat kind of HP will your spindle be capable of? For a machine like this, I assume it\'s a big one. And I assume that this is for metal work. Your cutting forces could be several hundred pounds if you have a huge spindle cutting metal, and that is not a trivial amount, as it can be for a home made wood router.
\r\n
\r\nFor my own build, I was a little bit surprised to see what kinds of differences there were between 5mm and 10mm pitch. It made a huge difference.
\r\n
\r\nTo answer your question, really, I\'d need to know the specifics, such as,
\r\n
\r\nWhat is the weight of that big piece you made, including the table, and including the largest work piece you might put on it, and including all of the bits, like the ballscrew and motor? Everything that would be moving back and forth.
\r\n
\r\nWhere is the torque graph for the stepper you want to use, using the appropriate power supply and microstepping? What is the motor inertia for the motor? What are the diameter (s) pitch and length of the screw that is not yet shown but will be used to move the big piece you have shown back and forth?
\r\n
\r\nWhat kind of servo are you thinking of, or are you looking for recommendations?
\r\n
\r\nWhat are your goals for acceleration (in G\'s) and top speed (in IPM)?
\r\n
\r\nWhat kind of HP spindle are you planning on? Do you know what the cutting forces might be? Easy enough to run some hypothetical numbers through a feeds and speeds calculator to see what the forces are if you know what kind of HP is available.\r\n \r\n

[stef110]

\r\n \r\n Thanks NIC for the help.
\r\n
\r\nHere is a picture off the current design base and column are still "subject to change".
\r\n
\r\n
\r\n
\r\nThe weight of the table will be 50Kg think that there will be a max of 100kg on the table so for the X axis there will be 150Kg load.
\r\nFor the Y axis there will be 260kg load when there is 100Kg on the table.
\r\n
\r\nThe x axis spindle is a 2005 and is 850mm long
\r\nY axis spindle will also be 2005 and is around 500mm long
\r\n
\r\nHere are the specs of the closed loop stepper i want to use right now:
\r\nhttp://www.leadshine.com/UploadFile/Down/ES-Md_V1.3.pdf I will use model ES-M23480
\r\n
\r\nWill supply them with 72v and the controllers on current machine are set to a micro step of 1600.
\r\n
\r\nI was also looking into these kind of servo\'s DMM | NEW DYN2 AC Servo Drive | AC SERVO DRIVE | AC SERVO MOTOR | ROTARY ENCODER and then the nema34 equivalent. So a 0.75Kw version.
\r\n
\r\nFor the spindle power i not yet decided, I am looking for a big servo motor because i need an indexer to led the spindel stop every time on the same spot because of the tool changer.
\r\nThinking somewhere around 3Kw will be fine. Right now i have a 1.1KW motor with a 2:1 acceleration on it to a chief 6000rpm with a 3000rpm ac motor. And for aluminium i have enough power.
\r\n
\r\nI don\'t have the idea of cutting steels with this new machine. I normally only work with alloy but if possible it will be a nice feature.
\r\nRight now i a chief speeds of 4000mm/m with nema24\'s 3nm and 1605 spindles faster would be nice but have no idea how fast it needs to be.
\r\n
\r\nsorry for the messy answer but i hope you right now have a feeling of what i am planning of.
\r\n
\r\nstef\r\n \r\n

[dbsharp]

\r\n \r\n I have purchased about 6 of these closed loop steppers (the ones from automation technologies inc, which are rebranded leadshines. I have had a lot of trouble with them. I\'ve gotten over current errors, they have lost position (encoder issue?), and I have even had them run away on me crashing my z axis into the table. I will admit I turned up the position following error to a pretty high number on the one that crashed, I have had another one run away that was all oem program and it didn\'t go far before it errored out. For wiring, I am very careful to use shielded and properly grounded cables and I separate out sensory from motor power wires where possible. They are generally very nice vs open loop steppers for higher performance, and I think they are very close to being fantastic. They just are not reliable enough for me to want to use them on anything other than a hobby router.
\r\n
\r\nOn my lathe conversion I bought DMM servos, they appear to be more advanced and have 8 bit security code in the encoder feedback. The safety and reliability to me justify the cost.
\r\n
\r\nPS Iove this build! I have started designing something similar a few times now, and have never really followed through. Mostly due to the cost, and backlog of projects on my list! I cant wait to see the ATC and this spindle in action.\r\n \r\n

[stef110]

\r\n \r\n I don\'t use steppers on my build, they are servo\'s from delta i know they look like big steppers but they are not!
\n
\nhttps://www.damencnc.com/nl/ac-servo...7rs/a815?c=120
\n
\nstef\r\n \r\n

[LazyMan]

\r\n \r\n Oh man that is a beast. No steppers for that thing...\r\n \r\n

[hanermo]

\r\n \r\n Nice start !
\n
\nMy advice is servos, absolutely, for the accuracy and acceleration, both very important.
\nFor any 3D milling work, mostly acceleration is the defining parameter, top speed is pretty unimportant.
\n
\nServos tend to accelerate and run real-world 3-5x faster than steppers, on complex work, ie other than box shapes.
\n
\nFwiw .. I never use the top speed of my servos, and limit the machine speed to about 20-40% of max.
\nAnd I use speed-rate override.
\nOn a lathe with 18 cm / 40 cm travels, position-to-crash is about 1 sec at top speed.
\n
\nMath:
\n10 ms to accelerate to top speed- 3000 rpm, = 60 revolutions/sec. (I also use much less than max accceleration. Too Jerky.)
\n1500 rpm at screw, 30 r/sec.
\nScrew = 4 mm /turn, 120 mm / sec.
\n1.5 secs end-end on x, typically about 0.75 secs.
\nAnd about 1 second on typical Z axis positioning, near the chuck.
\n
\nLathe is 12x24" light industrial.
\n
\nI suspect You will need\r\n \r\n

[hesham morsy]

\r\n \r\n Your workmanship is top notch. Any factory would be proud of a product that looks like that
\r\ni copied the quotation from NIC 77
\r\nalso for BF25 cnc mill conversion
\r\n:cheers:\r\n \r\n

[stef110]

\r\n \r\n last 2 days are spent on welding the frame, after some welding took a break to let the thing cool down a bit. Next step will be heat treading.
\n
\n
\n
\n
\n
\nstef\r\n \r\n

[NIC 77]

\r\n \r\n I\'m quite jealous of the awesome looking stuff you\'re making. Keep up the good work.\r\n \r\n

[stef110]

\r\n \r\n Not much progress to announce, frame is right now at the heat treading company and have to wait till i get it back.
\r\nMean while i received my delta servo motor and drive and it looks quite nice!
\r\n
\r\nThis weekend started a new awsome project i just wanted to share with you guys.
\r\nWe are building a 1.5kg combat robot. The main frame is milled out of a 3.5kg chunk of 7075 alloy. And milled down to a frame of 258 gram.
\r\nFrame is milled on my current g0704 mill and took about 12 to 14 hours including making cam, clamping and dialing in.
\r\n
\r\n
\r\n
\r\nMore pictures and updates on our facebook page : https://www.facebook.com/metalskullrobotics/
\r\n
\r\nStef\r\n \r\n

[Hezz]

\r\n \r\n

\r\n

\r\n

\r\n

\r\n \r\n \r\n

last 2 days are spent on welding the frame, after some welding took a break to let the thing cool down a bit. Next step will be heat treading.
\n
\n
\n
\n
\n
\nstef

\r\n \r\n

\r\n

\r\n

Great job Stef. I really like the way your doing your X axis. Looking forward to the rest of the build. Hope it didn\'t cost too much to heat treat it. Can I ask what the little unused cut out tabs are for.\r\n \r\n

[stef110]

\r\n \r\n @nic this robot will have a spinning drum on the frond with hardox teethes. It will spin around 12k rpm.
\n
\nThis is a render off what we are making.
\n
\n
\n
\n@hezz
\nThose cut outs are for tyraps to nicely order wires and oil lines.
\nHad a email from the treading company and it is done so now i can make an appointment with the guy, who will mill the frame.
\nBye the way the heat treading was free, the company was very helpful and found it such an awesome project that the wanted to help me with it.
\n
\nstef\r\n \r\n

[Zach_G]

\r\n \r\n Hey Stef, quite a few combat robot builders who took the plunge into DIY CNC here to feed the hobby. Love your bots and your mill build!
\n
\nZach\r\n \r\n

[eat5hams]

\r\n \r\n any updates on this great looking machine?\r\n \r\n

[stef110]

\r\n \r\n not yet, project is on a low pace right now due some other more important projects. Frame will be milled in the next few weeks after that i will do an update.
\n
\nstef\r\n \r\n

[NIC 77]

\r\n \r\n Are you still going to use concrete for the rest of it?
\r\n
\r\nI just love the way you\'ve made the steel work so far. I wonder what would happen if you continued in the same building style for the rest of it and made it out of steel?
\r\n
\r\nI\'m sure whatever you do will be fantastic.\r\n \r\n

[eat5hams]

\r\n \r\n Sounds great, keep us updated as you have time! Very intrigued by this machine. I have no idea what heat stress relieving costs, I guess I need to make some calls! Love the laser cut design. And I\'m also curious about the pros and cons of using concrete like you are planning and continuing with steel as Nic77 suggests. Anyways, looking forward to seeing your progress. Cheers\r\n \r\n

[stef110]

\r\n \r\n Time for an update, Steel have been milled down to size. Also the mounting block for the bed and linear rails is done. Putted everything to gather to see how it fits and i can tell you really nice
\nNext step will be making an nut bracket so i can test the servo motor and see how it moves.
\nEnjoy the pic\'s
\n
\nStef
\n
\n
\n
\n
\n
\n
\n
\n
\n
\n
\n
\n
\n
\n\r\n \r\n

[Chazaxl]

\r\n \r\n Nice. What are the bellows made from? Own design / build or something purchased?\r\n \r\n

[stef110]

\r\n \r\n They are bought, and made from stainless steel.
\n
\nhttps://nl.aliexpress.com/store/1202...591050600c0yhV
\nJust send them your shape and dimensions and the make it for you custom.
\n
\nstef\r\n \r\n

[pippin88]

\r\n \r\n Looking fantastic\r\n \r\n

[eat5hams]

\r\n \r\n Looks Fantastic!! Thanks for the update!! Excited to see the rest when you get to it!\r\n \r\n

[rocketflier]

\r\n \r\n Outstanding. Be interested in hearing your thoughts/ideas on the concrete, forms and rail attachments.\r\n \r\n

[stef110]

\r\n \r\n just a small update, if you can call it like that.. Project is currently on a dead page. haven\'t done anything on the design.
\nI do have a small movie of the first movemenst on the X axis this is at max rpm of the servo. So it should be around 15m/min.
\n
\nhttps://youtu.be/_V1ri2vpJgY
\n
\nstef\r\n \r\n

[CNCMachineplans]

\r\n \r\n Very nice. Can’t wait to see more.
\n
\n
\nSent from my iPhone using Tapatalk\r\n \r\n

[stef110]

\r\n \r\n I am struggling a bit how to make the connection between the column and the base. I will cast in steel plates so i can bolt the column down to the base. the surfaces of those plates will be machined after the casting but that will never be 100% right so i need to be able to tram the column.
\nwhat i am thinking about is put some big gub screws on each corner so i can adjust the gap between the plates to level it out. and after hat eject the gape between with some epoxy. when going for this option i think i don\'t need to machine those plates at all after casting.
\n
\nThose plates right now are 220x300mm each so they are really big.
\ni think i have to mill in an grove and put in a big rubber open o ring around the edge. and then inject the epoxy on one side until it is completely filed.
\n
\nHow do you guys think of this method?
\n
\nstef
\n
\n\r\n \r\n

[Hezz]

\r\n \r\n

\r\n

\r\n

\r\n

\r\n \r\n \r\n

I am struggling a bit how to make the connection between the column and the base. I will cast in steel plates so i can bolt the column down to the base. the surfaces of those plates will be machined after the casting but that will never be 100% right so i need to be able to tram the column.
\nwhat i am thinking about is put some big gub screws on each corner so i can adjust the gap between the plates to level it out. and after hat eject the gape between with some epoxy. when going for this option i think i don\'t need to machine those plates at all after casting.
\n
\nThose plates right now are 220x300mm each so they are really big.
\ni think i have to mill in an grove and put in a big rubber open o ring around the edge. and then inject the epoxy on one side until it is completely filed.
\n
\nHow do you guys think of this method?
\n
\nstef

\r\n \r\n

\r\n

\r\n

I think it\'s a good method. One thing that you could do is machine a shallow pocket in the plates to accept a filling of epoxy or maybe even a filling of squeezed in silicone glue to give some damping and some extra holding power. This way you might be able to take it apart if you ever needed to.
\n The areas of the plates around the bolts would be as flat as possible and then you would align the column using shim stock to get it dialed in and tightly bolted. Then fill the pocket with epoxy or some kind of adhesive damping material. Or this might not be necessary if there are enough bolts and the surface area under the bolt areas is sufficient for the stiffness required.\r\n \r\n

[Trotline]

\r\n \r\n I don\'t see why that wouldn\'t work.
\n
\n Do you plan on post-tensioning the column? It won\'t see huge loads, but the repetitive nature of what loads it does see could conceivably cause the column to crack. (I\'m just thinking out loud here, with no numbers to back me up, and I\'m certainly not criticizing your excellent build.)\r\n \r\n

[NIC 77]

\r\n \r\n It seems reasonable to me also. But I\'ve never done it.
\r\n
\r\nMy preference would be to use a big steel beam(s) structure, then fill that with epoxy granite or concrete when you\'re done.
\r\n
\r\nAn alternative method would be to use stainless steel shim tape for fitting adjustments. I have some of the stuff and I love it. Then you could put some mold release on one side and when you reassemble, the force of gravity would squish out any extra epoxy.
\r\n
\r\nBut like I said, what you are proposing sounds reasonable, and could would allow for a more precise adjustment than the alternative I suggested.\r\n \r\n

[RotarySMP]

\r\n \r\n Forger the o-ring. It is common in industry and also building to thread holes into the top matching plate, and use screws to get the gantry aligned and then inject an epoxy grout into the gap. Just seal the edges with silicon before injecting.
\nMark\r\n \r\n

[rocketflier]

\r\n \r\n I recall someone doing something like this, possibly in the huge thread. They cast tubes in so they could inject the epoxy from above. Wax 1 surface, square with the set screws and inject. I don\'t recall if he drilled for alignment pins after. That is if you ever plan to pull them apart, saves time for reassembly.\r\n \r\n

[rybov]

\r\n \r\n Here is a nice video showing using epoxy grout for aligning the column to the base.
\n
\nhttps://www.youtube.com/watch?v=URtU1XImjWE
\n
\nHe has a few other videos on building a concrete VMC.
\n
\nBest
\nJacob\r\n \r\n

[stef110]

Hello my name is Stef, I already make some posts on this forum. I have converted an bf25 (g0704) to cnc and used it now for about a year. Right now I want something bigger and more rigid.
http://www.cnczone.com/forums/bencht...22688-cnc.html

After a while of gathering parts and looking to different designs. I have start building yesterday right now the x axis is starting to get shape.
The x axis is made out of steel, the base and column will be made of concrete (uhpc) Travels will be X600 Y300 Z550. It will have an BT30 spindel with a 16 position tool changer on top.
I will use leadshine closed loop steppers to drive all the axis and use a USBCNC control board to control everything.











will keep you guys updated.

stef