idea for z axis improvement

[ve3sjk]

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.. .

[ve3sjk]

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.

[D-Byte]

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.

[ve3sjk]

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

[D-Byte]

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. If you have more wishes or ideas a bout the z-axis just put them here in this issue.

[ve3sjk]

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.

[ve3sjk]

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.

[ve3sjk]

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.

[D-Byte]

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.

[joco-nz]

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?

[D-Byte]

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.

[joco-nz]

@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.

[ve3sjk]

@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.

[ve3sjk]

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]

solid frame idea

[joco-nz]

@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.

[ve3sjk]

@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.

[joco-nz]

@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? Your clip approach would definitely fix it. Or we look to adjust the design of the x carriage slightly.

[joco-nz]

@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!).

[ve3sjk]

@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.

[ve3sjk]

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.

[CarlosGS]

It looks so amazing!! Thanks for sharing! :D On 14 Dec 2014 20:02, "ve3sjk" notifications@github.com wrote:

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.

[image: 2014-12-13 20 32 29] https://cloud.githubusercontent.com/assets/7632604/5428841/c0a50124-83a1-11e4-9d38-a08d57818fdb.jpg [image: 2014-12-14 14 52 03] https://cloud.githubusercontent.com/assets/7632604/5428842/c575a7ee-83a1-11e4-87aa-f985d666d88f.jpg [image: 2014-12-13 20 39 29] https://cloud.githubusercontent.com/assets/7632604/5428843/d22aaf2a-83a1-11e4-890f-9c1d5a3cda96.jpg [image: 2014-12-13 20 42 05] https://cloud.githubusercontent.com/assets/7632604/5428844/d490725e-83a1-11e4-8552-f79b74a3255c.jpg

Reply to this email directly or view it on GitHub https://github.com/carlosgs/Cyclone-PCB-Factory/issues/32#issuecomment-66927234 .

[joco-nz]

@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?

[D-Byte]

@ve3sjk and @joco-nz making the Z-nut captive is 10 minutes work ;-) after two weeks of trial and error in OpenSCAD. Just making the z-nut holder captive was not an option because the linear x axis bearing is behind it. So i made a option in my settings file where you can chose the alt_z_nut option. That place the z nut under the linear x axis bearing where there is more room. I don't know if the threaded z rod length allow this also there is the problem of the captive nut holder have some tolerance for printing and fitting the nut. I think this is not a good solution. Maybe you two have a solution for these problems in mind. I think glueing the z-nut or the solid frame is a better solution to this problem.

[joco-nz]

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.

[ve3sjk]

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.

[joco-nz]

I would suggest you look at the Marlin version that ships with Cyclone 2. It has the correct settings in it. These are relevant lines:

#define Cyclone_XY_Gear_Ratio 21.0/21.0 // Number of tooth (motor/rod)
#define Cyclone_Z_Gear_Ratio 8.0/15.0 // Number of tooth (motor/rod)
#define DEFAULT_AXIS_STEPS_PER_UNIT   {3200.0/(Cyclone_XY_Gear_Ratio*1.25),3200.0/(Cyclone_XY_Gear_Ratio*1.25),3200.0/(Cyclone_Z_Gear_Ratio*1.25),800}  // steps per unit for Cyclone

[ve3sjk]

@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.

[ve3sjk]

@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.

[ve3sjk]

i got it, sweat and simple a little plate with a slot in the front the size of the M8 threaded rod. Put the captive nut on the z axis in, then acetone the plate in not going to move after that. Just need to project that tab were the nut goes onto a flat surface and print it maybe 1mm thick.

[joco-nz]

@ve3sjk re probing. From what I can tell the probe function just uses the Z endstop. So if you can home Z correctly then the probe routine should see the Z endstop fine. The only other angle I can think of is that the Cyclone 2 Marlin has tweaked the the probe G-Code in some manner.

I'm using a mega 2560 with the Marlin V1 from the Cycline 2 repo and it "just works". The only tweaks I think I needed to do was on the endstop logic to get correct settings for NC and NO behaviour on the micro switches.

[ve3sjk]

@joco-nz i moved to the version in the cyclone v2 repo after tweaking the size of my machine i got probing to work, i think my version from the marlin current repo will work as well. The issue i think was i was homing the z axis to max not min value since i have installed all 4 limits. I put a piece of double sided FR-4 on the work bed using doubled sided tape and tried the auto level function again, when i hit raise probe it raises till it hits the z-max limit, then a zero probe took me to the surface of the copper clad. I have one probe on the copper and the other on the v-bit in the dremel. Looks great, now i really want to try a cut tomorrow. Here is the results of my probe, lol. I think i can see the edge of the tape under the board. I can see me engraving a Zippo at some point in future.

[joco-nz]

Nice. It's quite a buzz when you get things working.

Just a note on the FR4 board but I'm sure you are aware of this. Make sure you have a system to deal with the dust from this fibre glass based board. While from the reading I have done it doesn't appear to be cancer causing its probably not good for you. So a mask and suction would probably be a good move.

[ve3sjk]

i have an issue with the probing in this code. If i leave it as is in the repo then i set min z to zero and set define_min_software_endstops as false, the unit homes at zero which is on the board but does not allow it to move below zero. If i set the min z to -3 then it homes to -3 instead of zero which i am pretty sure is going to screw up the cut. Using the repo in the v2 files.

// ENDSTOP SETTINGS: // Sets direction of endstops when homing; 1=MAX, -1=MIN

define X_HOME_DIR -1

define Y_HOME_DIR -1

define Z_HOME_DIR -1

define min_software_endstops false // If true, axis won't move to coordinates less than HOME_POS.

define max_software_endstops true // If true, axis won't move to coordinates greater than the defined lengths below.

// Travel limits after homing

define X_MAX_POS 240

define X_MIN_POS 0

define Y_MAX_POS 205

define Y_MIN_POS 0

define Z_MAX_POS 50

define Z_MIN_POS -3

define X_MAX_LENGTH (X_MAX_POS - X_MIN_POS)

define Y_MAX_LENGTH (Y_MAX_POS - Y_MIN_POS)

define Z_MAX_LENGTH (Z_MAX_POS - Z_MIN_POS)

[CarlosGS]

Hi, the firmware should allow it to move below Z=0 without incorporating any changes. Make sure that the Z min endstop (the two electrodes) are disconnected and do not make contact during milling, as that would prevent movements below Z=0 On 18 Dec 2014 19:42, "ve3sjk" notifications@github.com wrote:

i have an issue with the probing in this code. If i leave it as is in the repo then i set min z to zero and set define_min_software_endstops as false, the unit homes at zero which is on the board but does not allow it to move below zero. If i set the min z to -3 then it homes to -3 instead of zero which i am pretty sure is going to screw up the cut. Using the repo in the v2 files.

// ENDSTOP SETTINGS: // Sets direction of endstops when homing; 1=MAX, -1=MIN

define X_HOME_DIR -1

define Y_HOME_DIR -1

define Z_HOME_DIR -1

define min_software_endstops false // If true, axis won't move to

coordinates less than HOME_POS.

define max_software_endstops true // If true, axis won't move to

coordinates greater than the defined lengths below.

// Travel limits after homing

define X_MAX_POS 240

define X_MIN_POS 0

define Y_MAX_POS 205

define Y_MIN_POS 0

define Z_MAX_POS 50

define Z_MIN_POS -3

define X_MAX_LENGTH (X_MAX_POS - X_MIN_POS)

define Y_MAX_LENGTH (Y_MAX_POS - Y_MIN_POS)

define Z_MAX_LENGTH (Z_MAX_POS - Z_MIN_POS)

Reply to this email directly or view it on GitHub https://github.com/carlosgs/Cyclone-PCB-Factory/issues/32#issuecomment-67544521 .

[ve3sjk]

@carlosgs i changed the homing back to zero and made both min and max endstop settings to false and it started working, i wonder if the two are not interchanged somewhere in the marlin code. If you make min software endstops false and not max it won't go below zero. I am using all the endstops on this unit.

[joco-nz]

@ve3sjk There could be a bug, i have a nagging feeling there might even have been mention of this on in the Marlin repo's discussions. I don't use the max endstops so I'm not able to easily test that. I can do a code review when I get home from work and see if there is anything obvious in the homing code. That will be ~6 hours away if you can wait that long. :-)

[ve3sjk]

@joco-nz I did get it working, i think the options are reversed somewhere for max and min software endstops. the min software were turned off originally but the max end stops were disabled completely. Once i turned off both of them it worked good. Not sure if this is expected behavior or a glitch in the settings.

[ve3sjk]

@carlosgs @joco-nz I was chasing a ghost on the whole below zero issues. My code had one warning and an important one. G00 X0 Y0 Z0..........this was resetting everything at the start so that it was not going below zero. I deleted the command in the code and now it cuts below zero.

Here is a novel solution to the captive nut on the x carriage, since i print my ABS in the replicator on a mirror plate, i use an ABS acetone slurry to put a thin layer of abs on the mirror before printing. with an acetone resistant oiling syringe and a good pull from the bottom of my slurry jar, that nut is not going anywhere..........the acetone evaporates so fast the the abs didn't even run down the sides.

[ve3sjk]

can i ask what is the correct procedure for cnc-gcode-controller, what are the right steps, i know if i home the machine x,y.z then go to autolevel it will drag the bit across the board, so i have to lift tool first. Do you zero tool before milling, or just hit milling once the auto-level is done, or do i auto level before even going to the milling tab. I know zero tool doesn't lift it after, so any moves after that will scratch the board unless you manual lift the tool. I think the auto level ends with the tool raised to a safe height.

[CarlosGS]

I home XY at a safe height once, then do autolevel (or zero tool). You shouldn't need to home Z manually. On 19 Dec 2014 20:03, "ve3sjk" notifications@github.com wrote:

can i ask what is the correct procedure for cnc-gcode-controller, what are the right steps, i know if i home the machine x,y.z then go to autolevel it will drag the bit across the board, so i have to lift tool first. Do you zero tool before milling, or just hit milling once the auto-level is done, or do i auto level before even going to the milling tab. I know zero tool doesn't lift it after, so any moves after that will scratch the board unless you manual lift the tool. I think the auto level ends with the tool raised to a safe height.

Reply to this email directly or view it on GitHub https://github.com/carlosgs/Cyclone-PCB-Factory/issues/32#issuecomment-67689651 .

[joco-nz]

Here are some of my learnings on this. I'm in the process of building a very detailed post for my build log on forums around gerber to flatcam to cnc-code-controller to milling so this will be a summary.

1. I home on x/y after making sure tool is about 15mm at the cutting tip above the work area. Push "get position" to ensure the controller is in synch with the firmware. I have noticed a few ad hoc situations where things did get out of synch. So now I am paranoid.
2. Move to a position where I want 0,0 to be and use set-position to make the x/y coord system be 0,0 at that location.
3. I tend to do a manual z home but as Carlos points out it isn't needed since the probing process does a z home to start with.
4. Milling - Carlos probably needs to set me straight on this but from what I can deduce milling and the probe map look to be pretty independent. You can mill away with no probe map in place, which I have done on mdf. i would guess that when doing a pcb doing an auto probe followed by cutting the isolation paths first. Then change bits and re zero z axis. Start the drilling. Change bits, re zero z and cut the board out. It might make sense to do the drilling first if there are very small traces.

Lol - so much for a short response. :-)

[ve3sjk]

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..........

[joco-nz]

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.

[CarlosGS]

Hi James, XZ was for sure the most complicated part of the design. Take a look at http://carlosgs.es/node/47 to see the previous iterations. I think the latest version is a fair trade-off between simplicity and robustness (seems to be working reasonably well). It also is quite easy to disassemble in order to transport the machine. So the main lines of the project will be kept as they are, until greater simplifications show to perform significantly better.

That said, please go ahead with your ideas, don't be reluctant to make branches of Cyclone (Martin's PortalCyclone is a good example of a parallel project that has been built by lots of people). Any new design will naturally have a number of "prototype" iterations before converging into a stable mechanism.

@Joco Thanks for sharing your work flow, it looks pretty reasonable! "from what I can deduce milling and the probe map look to be pretty independent." Yep, that's exactly right "It might make sense to do the drilling first if there are very small traces." That's very true as well, you get much better quality if making the drills first.

@ve3sjk Congrats on those first cuts!! Also neat solution to lock the nut in place with ABS slurry, it's definitely not going to move :P I admit that I don't see exactly how the rod distribution that you're proposing would work - as I said to James, you're more than welcome to try other solutions for the sake of robustness, speed, etc :)

On Sun, Dec 21, 2014 at 11:54 PM, James notifications@github.com wrote:

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 https://github.com/carlosgs , @D-Byte https://github.com/D-Byte are you able to give us some insight into the design decisions made in placing the rods in their current positioning?

Thanks.

Reply to this email directly or view it on GitHub https://github.com/carlosgs/Cyclone-PCB-Factory/issues/32#issuecomment-67790569 .

[ve3sjk]

@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.

[joco-nz]

@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 And if ir proves worthy/interesting @D-Byte can do the magic he does and fix my crap coding. :-p

[ve3sjk]

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.

[joco-nz]

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. This approach allows me to keep the the X carriage at the same width and so no change to the standard layout dimensions and work area. It is also sized based on the standard smooth rod lengths however if you could increase the potential Z travel significantly by setting an increased smooth rod length and resizing dimensions accordingly. Interested in views on alterations and improvements. I have a nasty feeling that parameterising this will be a real bugger since the curve is made of two bezier curves.

[ve3sjk]

@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.

[joco-nz]

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.