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idea for z axis improvement #32
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I am finished the basic build now, i have modified it slightly by using 2 more y-smooth rod holders at the back and cutting out the holders that are part of the side frames, it was pretty easy to do. I have centered the tool point at the center of the y-axis distance. Haven't put a work bed on it yet, This give me 13.5 inches of total length on the y-axis and 12 inches on the x-axis. i would say it took me approximately 25 hours to print everything and about 4 hours to lay it all out too this point. Next thing i think is to extend the y threaded rod, i didn't have a piece long enough but my thought is to bring it flush with the front y smooth rod holders. |
Hi @ve3sjk i think this is what you want als a top for the z-axis. Its a fixed top in the x-carriage the nut need to be removed and there need to come a place for a radial bearing. And a new z-carriage need to be designed. |
pretty close i would have the bearings on the outside, excuse my handwriting maybe this might help you visualize it. this would be a side view from the left side, the upper bearing would have a nut on the inside to prevent it from slipping down, so it would be nut, bearing, nut the a new z carriage would look something like this, with just a mounting plate facing the front of the machine you could incorporate backlash if you wanted not sure its needed on Z. i know i have seen backlash nuts before there as well |
You are right, there is still a lot to do :-) . I think i will try work on the files around Christmas when i have a little more time. But i like the idea that the threaded rod stay in place and not move up or down. |
thank your for working on it, i am good with the idea but bad with open scad, lol. but i am learning fast. On my machine i have offset the x axis to -180 since i have 330mm smooth rods, Its a bit more plastic and it going to need some work, i am printing this part right now, One thing i am having trouble with is where in the code is that Y-smooth rod holder that is attached to the x-frame being built. I built the machine with two extra y-smooth rod holders in the back cutting off the ones that where there, but i like the structure of this frame, i had to offset the bottom back mounting hole in the back of it, as the smooth rod holder just rendered on top of it. This puts the spindle tool tip dead center of the y axis. Still working out how to calculate the new workbed size to max out the working area. |
one other thing i have modified is i took the end stop assembly out of the standard parts file and made it standalone, added the parameters for it to the configuration files. I going to use highly VS-15 roller switches instead, this way i can modify the file for different kinds of switches. I am thinking and option in the config file to choose which one you want. Still want to get all 4 endstops on the machine, i think one can be added to the front Y frame for sure then its a matter of getting on on the right X frame. |
i noticed you created a v2.1 branch in your repo. Is that for the new version release. I am wondering how i keep my repo up to date with your changes. I forked from yours. |
Yes the v2.1 branch is for the new release. Carlosgs released v2 last weekend. I think you need to create a new branch in your repo and than pull my branch in it that way you have my new branch and than you can update that again. |
as described in CarlosGS#32 (comment)
I like the ideas on the revised Z-Axis part. It looks to have similar concepts per the portalcyclone project? Is there value in looking at how that project does this part? From what I can see it seems to be pretty sturdy. @ve3sjk re the the overall adjustments you are making. I was wondering what length you were using on your X and Y smooth rods? Are you experiencing any "sag" over the longer lengths or did you use 10mm or 12mm diameter rods to counter that possible issue? |
Hi @joco-nz thanks for pointing out the portalcyclone. That z-carriage looks very sturdy and i think something like that will make a perfect fit for this project. I will look at it when i have some more time because it need to be configurable for rod diameter and length and bolt size and other parameters. |
@D-Byte Agreed - you won't be able to just take it as it is as I think only the STL is published. So you are still going to have to code things up. However having a target shape instead of a blank sheet of paper always helps. |
@joco-nz I am using 330mm M8 rods, i don't see any sag that would cause an issue but if it becomes on i will switch to a bigger smooth rod. As a quick test i placed a temp work bed on the system centered on the y-axis. I put two old ide hard drive on it weighing 2.2 lbs. I can't measure any deflection with a micrometer with that on it. |
is the captive nut for the z axis that is held in the space on the x carriage supposed to be glued in, from what i can see if it isn't then as soon as the tool pushes down on the circuit board, the z axis threaded rod just lifts out of place at that point making downward pressure unobtainable. Maybe i missed something on assembly |
@ve3sjk re the captive nut on the z axis, I don't believe it needs to be glued based on the loads intended for this design, ie PCB milling. With the weight of the spindle/Dremel there should be enough pressure to have a high speed rotating bit cut into a PCB copper layer and substrate with no issues. I have been doing milling tests on mdf with no issues. Milling something harder like aluminium might present more of a challenge but I hope to be in a position in a few more weeks to report on my findings in that space with the v2 design. |
@joco-nz I don't think i have ever seen a cnc where the z-axis does that, seems like it would be a better idea instead of having the nut drop in the way it does would to have a slot there to captivate it fully. I understand the concept but in my thoughts, the amount of downward pressure is very dependent on what spindle you use, if the spindle is very light, then its not going to get much downward cutting force. Maybe i can figure out a little clip that pushed onto the tab where the nut goes now to lock it into place. |
@ve3sjk Agree hence why I framed my response with reference to the design parameters of the V2 cyclone. i.e. Dremel Spindle. I'm looking into a light weight air powered spindle which will have exactly the issue you have identified due to negligible weight. So we will need to find some form of solution. :-) I have this nagging feeling that you could probably added a spring/nut backlash system in the hexagonal hole where the threaded rod pass through under where the existing nut sits. I'm at work so I can't test the fit to see if that is viable. But such an approach would at least off some extra pressure while also allow some give if there was an error and too much downward force was being applied? |
@ve3sjk sorry another thought. Of course the whole nut issue would appear to go away once we sort a more solid Z axis design akin to your hand drawings above (good ideas by the way!). |
@joco-nz I don't think a spring would do it as the rod needs to thread down in the design so you would need to captive both nuts that way. A full frame would solve it in a new design, in the current design i suppose it just a matter of relocating the nut. Wish i was better at openscad, i think it would be a matter of selecting that front face and putting slot in it the thickness of the nut after removing it from the top. |
Pretty well ready to wire it now, variant Cyclone PCB Factory, work bed size is 300mm x 210 mm. X x y axis 330mm rods. Tool holder is a work in progress, i have modified the top plate to fit a Dremel XPR 400 and used two top plates to get it mounted. In the process of modifying the vacuum cleaner attachment to also fix the XPR-400, and getting the wrench slot to render properly. Since the work bed is 12mm thick i have room to mill it smooth when every think is running, although i am pondering the idea of milling some T-slots into it instead. |
It looks so amazing!! Thanks for sharing! :D
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@ve3sjk Awesome build! And I love the increased size. You have inspired me to look at how I would "upsize" my build over the summer holidays (winter for you northern hemisphere folk). On the z-frame front. I'm not a bad hand at OpenSCAD so might have a crack at that improved frame. It won't be a flash a bit of coding as what @D-Byte will crank out but I have time on the train each day to work on it so if nothing else it might serve as a raw base for others to work with. @ve3sjk do you have any views on the vertical dimensions of the solid z-mount? |
@ve3sjk and @joco-nz making the Z-nut captive is 10 minutes work ;-) after two weeks of trial and error in OpenSCAD. |
Can be enabled in the Default_config.h by settings alt_Z_nut = true
This or a spring based system which I proved tonight and which can be setup with no reprint needed will stop the threaded rod nut from moving out of its trap. BUT it will not solve the fundamental issue. If you lower the Z axis faster than the rate of cutting into the milling target, as based on the weight of the spindle, said spindle will get left behind as the threaded rod and associated bearing lowers faster than it does until the rod gear is no longer engaged with the motor gear. Until we move to a setup where the Z carriage has a similar captive nut model as used in the X and Y axis along with a similar fixed position to anchor the motor and gearing off this issue will remain. At least that is how it seems to me after moving stuff about and pretending to have just this failed cutting situation and seeing what parts moved and what didn't. |
I am trying to figure out the settings for Marlin for the axis steps per mm, If i put 2560 on line 495 of configuration.h it shows a 256.01 on the screen, If i tell it to move 10 mm it moves 1 mm, and if i tell it to move 100 mm i get 10 mm. I am working from a new fork of the latest version of marlin. |
I would suggest you look at the Marlin version that ships with Cyclone 2. It has the correct settings in it.
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@joco-nz thanks that did it, just dropped those lines into my fork and it changes to 560 i think in the lcd display, 10 mm is 10 mm now. |
@D-Byte I think i am just going to glue mine in for now, i don't really like this way of mounting the dremel i will move to an actual spindle motor as soon as i can. The real solution is solid frame, that way the z-threaded rod is held in solidly held in place between two bearings. The sled that moves inside it can be pretty simple after that, it just needs smooth rod holders and a fully captive nut, i don't think backlash is needed on this axis. I still think a flat surface facing front on the sled with just mounting holes so one could can the tool head easily. I can see my m8 threaded rods are to be desired, lol. Going to have to source some straighter ones. I am thinking m10 sounds much better for those and maybe even the smooth rods. My machine has come to life, all 4 limits are in, and my x and y are moving now. I can even get it to follow a board i made some time ago in Cnc-Gcode-Controller after figuring out the proper output from eagle and pcb2gcode. Perfect output no errors or warnings in cnc-gcode. Need to get the z-axis moving as is for now, wanna see it cut something now that its homing x and y perfectly for a final cutting dimension of 240 x 200, preliminary test make me thing the pin definition for the probe maybe wrong for my build. I think it was 27 in the defines added to the pin.h file, i am wondering if that is something different for the mega 2560. i can trigger my z-min with a ground but i don't think the probe is seeing it. |
After some thought i am not sure a full frame z carriage will work with the current layout of the x gantry smooth rods, from observation of my current build. I have some pretty bad threaded rods although i have been able to etch with the unit. I see that almost all the wobble or error in the threaded rods is translated to the z carriage and the tool tip. Its almost amplified really the longer the z threaded rod gets. A full frame in my mind would only benefit if the x smooth rods were parallel with each other so that the full frame z carriage can ride between them instead of on top of them. If you made the opening solid where the aligator clips are on the x frames and oriented front lower smooth rod to be below the threaded rod and in the same plane as it and the upper smooth rod, then a z carriage could ride between them. this of course causes height problems and potentially issues with build volume when printing. I am curious in modifying it in such a way. If i can get the current y-frames to line up that way. Since i elongated my build originally by simply adding 2 extra y-smooth rod holders in the rear of the unit and cutting out the y-smooth rod holder that were part of the y-frame. I can see no issue with creating a raised platform to mount the y-frames higher and independent to y axis. Its just a matter of squaring the axis to each other at build stage. In this was my workable height can change based on how much more i raise the different y frames above the x-axis. the higher the smooth rod separation the more z travel you would get in this scenario. A z carraige or tool holder in this case would kind of look if you took the worked and snapped it facing front on z axis frame. some initial cuts to try the system out, not really that bad considering my threaded rods are really warped and my z xis has a lot of movement in it with the xpr-400 Dremel. Oh yea, and of course the signs of forgetting to raise the tool after zeroing it.......... |
I had come up with an idea to support a more solid design on the X/Z Carriage but it was a compromise based on keeping the smooth/threaded rods in their current position and working with the carriage width as it currently is. If we are prepared to really redesign things by moving the placement of these items around then there are more options available to us. I have noticed that majority of designs on CNC machines that I can find have the smooth rod equivalents in the vertical plan, so I assume there is a reason for this other than "it's easiest"? @CarlosGS , @D-Byte are you able to give us some insight into the design decisions made in placing the rods in their current positioning? Thanks. |
Hi James, XZ was for sure the most complicated part of the design. Take a That said, please go ahead with your ideas, don't be reluctant to make @JoCo Thanks for sharing your work flow, it looks pretty reasonable! @ve3sjk Congrats on those first cuts!! Also neat solution to lock the nut On Sun, Dec 21, 2014 at 11:54 PM, James [email protected] wrote:
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@CarlosGS This is the gantry i had on another CNC i assembled a couple of years ago. It has the smooth rod oriented vertical. It was moving gantry but the x axis is pretty well what i am thinking. |
@CarlosGS thanks for pointing to the history post. I think I will work on a variation to the existing X Carriage which will support the type of fixed Z rod position that @ve3sjk has been talking about with the moving Z mounting plate. I think this would be more an evolutionary approach than revolutionary and could be more easily incorporated as build variation at a detail level instead of material design branch since it will use the same rod positioning as exists today. If nothing else it gives me something to tinker with in OpenSCAD. :-D |
I am certainly not looking for making design changes to the main design, just tinkering and trying things with it as i go. I suppose i have more experience with the type of x carriage i have been thinking it needs for my purposes. Of course i am looking to do more than just pcb's with it, lithophane, light milling, wax molds, and if possible even 3d print as well. @joco-nz i am game for printing anything you design, i have a few pounds of abs and lots of time. After some initial testing i have decided to make some changes, just mock up till tomorrow when i will make a couple of raised towers for the x carriage, as it is in the pictures it would give just about 5 inches of space below the x gantry, plenty of build volume for 3d printings as well as doing circuit boards, I have another 5 full size butcher blocks left, so i am sure i can get something done pretty fast. The large box above electronics is made so an atx power supply will fit int the back, the front face plate just behind the lcd will have vent holes drawing air over the ramps board as long as the power supply is on. @CarlosGS something has certainly changed in the current repo for marlin, i am working great on the version in v2 repo, i can get everything working but the z-probe in the latest marlin. It will zero the tool fine but it stops right after the first probe. Just can't figure out what changed. |
This is my concept hack to date. I still need to work through the motor mounting and obviously far to much plastic in use in this but hopefully you get the idea. |
@joco-nz I think the large curved area might be a breaking point after printing unless you printed with a very large infill or even solid. I find it the same weak point on the y-smooth rod holders as well. I am back from my tangent and the new machine has a much larger z clearance now, just about 125 mm from bed to the bottom edge of the x-carriage. The frame ended up far more solid than i could hope for as well. |
Wow - BIG AIR! :-D Sounds like you are looking for something to do double duty as a 3D printer system as well? Otherwise I am intrigued to understand what you plan to use that extra clearance for. Re the "big curve", yes it has a potential for a week spot but I'm not sure how much load it will actually be under. Given things pretty much work today with no top support and we are investigating a way to have a (ideally) more stable setup to support a fixed Z axis instead of a floating one. Anyways I'll keep plugging away and refine things to the point it could be mounted and tested. I have found that the 3d honeycomb pattern from Slic3r 1.2 produces quite strong parts that are efficient on plastic. |
@joco-nz for a couple of reasons, 3d printing for sure i think it would make a great PLA printer. There is a way of carving lithophanes using a rotary axis on a cylinder, i am aiming to add that axis at some point although that may be when i move it to gecko drives and a real breakout board, I believe Mach 3 was developing a plugin for 3d printing. I am not sure if Marlin can do rotary axis although i suppose that is or could just be a extruder motor drive. With z axis front bracket shaped like an L upside down i should be able to reach the bed no problem and keep the working travel on the z threaded pretty low. I am using 3dSimplify Software with a rectangular infill at 22.5 -22.5 so i get a tight x pattern inside, the small angle makes sure it stays x pattern in spaces that are narrow. I used the honeycomb in Makerware, 3d simplify doesn't have that infill pattern yet. I am pretty sure i will find a load of uses for this machine once its completed. Hell i started working on vacuum tubes, lol. Now i can print my own gears........and do fast turn around prototyping on the fly. And i don't need and acoustic coupler to posta message. 3d Printing and CNC are going to make my metal nippers form radio shack obsolete. I have to figure out a good spindle, any suggestions or are you going the Dremel way, i always thought the run out in the rotary tools was too high for pcb work plus its a lot easier to build a solid mount for a cylinder that is all one size. I do have an MBE extruder sitting on the bench so a mount for that is on the list. |
@joco-nz looks pretty good, i sometime put mineral oil or turbine oil on the board when it cuts so its cutting in a puddle of it, cleans up the edges a bit. The burring i think is feed rate, moving the cutter faster than it can cut. If you watch the bit when it is cutting isolation if its bouncing around before catching the board when plunging, the z feed rate is too fast. My first test were around 20 - 50 on x,y,z. Then tweak up from there. Looks like a v-groove bit maybe 60 degree. Adjusting the speed of the dremel as well, i think v-grooves like around 15k on the spindle. Be a good feature to get it to remove the unwanted copper in the islands like around the pad that is isolated by the letter D looking shape. |
@ve3sjk Your build looks impressive! Congrats! @joco-nz Nice! Please find my answer in the Google Groups thread On Tue, Dec 23, 2014 at 10:47 AM, James [email protected] wrote:
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@D-Byte i was look over the alt z axis files in the repo i wonder if it would be possible to do this with it. I would love to print it that way to test since. I think in the end it would end up being the sled that moves inside a fix z axis frame, for now i think i can make it work in my enlarged build if it slide on the smooth rods. What are people getting for feed rates maximums i know i can move the x and y axis at 500 mm/min but i am sure cutting is going to be far slower. @CarlosGS your are right i think it works out to around 8 mm/sec at the most based on real test. Pretty sure i will abandon it as a printer, i guess the threaded rods are what slow it down. I wonder what would happen with acme screws instead. Or is it motor size and torque. A hot wire foam cutter is a easy possibility for the extended height and i can still use the space for a rotary axis under z. The just slide jigs under it for pcb work. |
Had some time to figure out a z-aixs for the extended z height. Since i am a real beginner in openscad i decided to start with @D-Byte 's alternate z axis and import it to sketchup to make some changes. Here is what i have so far. Still needs some work, like getting the lm8uu bearings fully into the slot. The bottom dremel mount needs adjusting since the dremel is not the same dimensions through it's length, I did add an L bracket to the inside square. I think i need to round all the edges for extra strength, these prints are not full infill but everything seem pretty stable. Only place i see movement is in the smooth rods above the lm8uu bearings which i think once the bearings reach the top of the slot will be taken care of..... |
@ve3sjk that's an awesome mod! How are you finding it performance wise compared to the original shape? I'm still tinkering away at the X/Z Carriage variation. Looks like this at the moment. Clearly still WIP and not ready for printing yet. |
@ve3sjk Your build looks pretty awesome, you should get some long endmills to make large format parts :) @joco-nz Your approach also looks very sturdy, my only advice is to take in account the presence of the X motor (as on that picture you would loose some X travel). It is definitely a more sturdy design for the Z axis. |
@CarlosGS the clearance is an issue with the current motor mount. I do think there is enough room but to do it and maintain a strong back arch I believe I may need to re-engineer the approach to holding the top linear bearing in place. But at the moment I'm just tinkering with ideas. :-) |
I know what code to comment out to remove the hole and alligator clips for the y-frames. i am experimenting a bit and wondering if someone can point me in the right direction. I want to move the bottom x smooth rod to be below and lined up vertically with the top smooth rod and threaded rod. Same spacing as from top smooth to threaded rods are spaced now. |
Here is a modification i have made to the z=axis using the original drive system, my ultimate goal is to make this just the z-axis sled riding in a full frame z-carriage. As it is the mount will hold an XPR-400 series Dremel tool. I started with the alt_z axis files and modified the motor block to be basically square, since i don't know open scad that well i imported that into sketch up and started getting a design together. The mount is 220mm from top to bottom and prints in three peaces, i used m8 threaded rod to clamp it all together and have three point mounts on the Dremel. the bottom plate should make it easy to add dust collection later. I had previously raised my x axis and with this design i now have 6 inches of travel height on Z. By adding washes between the motor mount and the second face plate i can shim the unit to square it up. Everything is extremely solid. Things to do yet, need a little more material on the left and right side of the motor block where the linear bearings go in, there are 4 lm8uu inside the motor block, round out the corners and adjust a bit on the tolerances. |
Looking pretty cool. Getting inspired to continue hacking my alternative mount. But been a bit distracted designing my 2'x4' CNC router. Sent from mobile device.
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It is indeed a very clever multi-part assembly. How does it behave? Can't wait to see it at work! :D |
@CarlosGS It seems really solid so far, i have not cut anything with it yet but its far better than my earlier tinkering. I did have to make a big change to the motor block part, kind of forgot to hold the whole assembly captive since i want be able to plunge into other materials. i have redesigned it again to put the z threaded between two 608 bearings withing the block. Things are tight and there is now extra movement in the z axis now, with the z captive nut abs slurry holding strong. Some pictures of the new motor block part, and some of the 2 piece Dremel XPR-400 mount. I do think i will move the Dremel further back on the mount as it stands out as is, i think i can trim that space by at least 20 mm. I do have to change the middle piece i call the motor block coupler i am really aiming towards a system that allow different tools heads assemblies to be mounted. As a bonus the new motor block being flat on the bottom gained me about 20 mm of depth on the z axis. |
Final dimensions work out to X240, Y230, Z107 mm. I took a parametrized T-Slot table design from thingiverse into Sketchup and was able to create a nice t-slop top for the work bed, since it's larger than what my Replicator 2x will print i cut it into 4 sections. Looks like it will work out well, need to tweak some of the screw holes but otherwise i am pretty happy with the outcome. PCB holder is next, the old one i printed will mount either across the x axis or across the y axis for different board sizes. |
That generic base looks really handy! What a CNC you're building :)
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@CarlosGS The T-base is working out great, i am redesigning it a bit with a better cut out so the pieces fit together better, plus the holes need to be sized up for M4. I made a test cut on the unit with a calibration file i found somewhere, lol. and since i had an old security camera around so i made a mount for it to give me some vision on tool head. yea, i often get off track as I design. I am porting a copy of the latest version of GRBL over to work on the Ramps 1.4 board I am using just seems to me i need more functionality as a cnc machine rather than it being a printer, I found a bunch of branches with auto level and probing upgrades for it. Did anyone ever look at that as an alternate control setup. I will post all my files on the my repo branch as soon as things are stable. I am working off version 8c of the grbl repo but i may start over with the latest which i think is 9g. I am designing a 4th axis 8c in the box puts this as T on A in my case for a rotary lathe axis. I am not sure if the marlin configuration would ever allow for the machining on a rotary axis. my test results very preliminary 60 degree V-bit, Depth 0.035, xy Feedrate 80, z feedrate 100, autoleveled machine vision, lol |
Forgot to comment, sorry. Looks awesome with the camera! |
Hi, I like your T-Slot table, do you want to share the cadfiles or just STL file? I would be very happy for them. |
Hi all, And if you want look the result (and my test) you can look this I do a TTrack remix here |
That's super neat and tidy! Thanks for sharing!! :-D |
I had tried to describe an idea earlier here are some pictures
I took the top plate of the tool holder, reversed it and placed it at the top of the axis, added a nut then the bearing then a nut then the gear.
the lm8uu are only to line things up, the smooth rods should butt into place instead, like they do on the x axis carriage so the top plate would be smooth above the rods, Won't need anything to the right of the black line
Side views, can make a raised platform section with an open slot from the back to all the stepper and gear to slip in
at the bottom its a matter of removing the gear, and moving that bearing somehow to the space below the black arrow, or it could go right through to the bottom of the x axis carriage
i think this creates a good solid frame that you could then put a z carriage in with backlash nuts like the other axis..
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