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Thread: Fixed Gantry Steel, wadeodesign

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    Default Fixed Gantry Steel, wadeodesign

    Hello. I'd like to share my first build with you all. I've documented this build on my website http://www.wadeodesign.com/cnc-router-build.html with pages devoted to an image gallery, description of design details, and a documentation page. I'll attach a couple pics to this post for a glimpse of the design but will not duplicate stuff from the site.

    The design is a fixed gantry steel construction using thk linear guides, ball screws, and overall goals of stiffness and simplicity. I tried to avoid fabrication methods (ie welding) in favor of purchase and machine parts.

    At the time of this post I've made a few 'first cuts' and now focused on installing switches, tweaking performance, & learning CAM prior to any real work. Still have much to do and will be leaning on all the great knowledge in this forum to help me put the finishing touches together.

    Hope you find something interesting on the site.
    Cheers

    Some basic stats..
    Mass: ~ 900 lb.
    Cutting area: X=30" Y=24" Z=6"
    Linear Guides: THK Linear Bearings X=HSR30 Y=HSR25 Z=HSR20
    Linear Motion: NSK 14-04 Rolled Ball Screws for X & Y with Lead Screw 12-02 for Z
    Stepper Motors: Schneider MDrive Plus Nema 23 with build in driver
    Spindle: TeknoMotor C41/47, 2.0 KW, 24000 RPM, ER25 with Delta 022E21A VFD (220v, 3 phase)
    Other: Mach4 software, Ethernet SmoothStepper

    Similar Threads:
    Attached Thumbnails Attached Thumbnails Fixed Gantry Steel, wadeodesign-img_20150822_190804373-2-jpg   Fixed Gantry Steel, wadeodesign-1443387695-png  


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    Default Re: Fixed Gantry Steel, wadeodesign

    Great build, looks like you'd be able to machine aluminium easily on that!

    cheers, Ian

    It's a state of mind!


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    Default Re: Fixed Gantry Steel, wadeodesign

    I hope we see some feedback on how some of those components are working for you. Especially the steepers with built in drives.

    Also that table everything sits on looks nice, kinda like some of the machine bases at work. Is that base a purchased item?



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    Default Re: Fixed Gantry Steel, wadeodesign

    Quote Originally Posted by wizard View Post
    Is that base a purchased item?
    The website referenced in the original post describes it as a Brute Machine Base, a purchased item.
    The table's top is 1" Blanchard ground steel so will weigh around 400 lbs by itself. Brute seems as good a description as any.

    Anyone who says "It only goes together one way" has no imagination.


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    Default Re: Fixed Gantry Steel, wadeodesign

    @aarggh – Thanks. Cutting aluminum is my primary objective with this build.

    @wizard – I’ll likely do a separate post on the Schneider MDrive steppers – still too early to pass judgement at this time but so far so good. As for the machine base, like cyclestart mentions above, it’s a Brute Machine Base and Inter-Lakes also makes a similar product. Both companies were nice to deal with and do custom stuff outside the standard ‘catalog’ products but expect to pay a high premium as these companies are not cutting any corners. I ended up purchasing used and the table was still ~$600. The big benefit of this base aside from pure mass is the blanchard ground surface which creates a nice flat reference for mounting the table rails and gantry uprights.



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    Default Re: Fixed Gantry Steel, wadeodesign

    Hello Wado
    Nice website, very generous of you to provide all the details. By DIY standards this has prefab features, someone with a large mill could have a little
    side-industry machining gantry tubes, such a pain to do on a small mill.
    You bought a lathe to machine the ball screws ? You wanted one anyway,,,, we're all tool junkies here, we understand.

    Anyone who says "It only goes together one way" has no imagination.


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    Default Re: Fixed Gantry Steel, wadeodesign

    If your cutting aluminium mainly, your table would lend itself nicely to build a containing wall around the outside so you could use flood coolant. This would maximise cutter life as well as clear the swarf so less re-cutting.

    That's what I'm planning for the machine I'll be building down the track, cleaning up after aluminium cutting on the wood CNC machine is a PITA.

    cheers, Ian

    It's a state of mind!


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    Default Re: Fixed Gantry Steel, wadeodesign

    Quote Originally Posted by cyclestart View Post
    Hello Wado
    Nice website, very generous of you to provide all the details. By DIY standards this has prefab features, someone with a large mill could have a little
    side-industry machining gantry tubes, such a pain to do on a small mill.
    You bought a lathe to machine the ball screws ? You wanted one anyway,,,, we're all tool junkies here, we understand.
    As for the providing the details... the documentation is still 'as is' build and depending on interest I may create a final build documentation package which generalizes the design and substitutes my ebay driven purchases with more standard component choices. I'm hesitant to put any time into that effort as I doubt too many people would want to replicate this build. So the documentation is posted for inspiration - I've also got all the pricing and web links in the parts list download so diy'ers can evaluate using some of the ideas in there build.

    You are correct that the gantry could be prefab'd without adding much cost to the gantry tube. You would really only need to have 2 sides of the tube machined flat and perpendicular and then drill your own holes. I highly suggest using this approach over an aluminum profile if building a fixed gantry. The benefits of mass, size options, improved stiffness, and even cost outweigh the fab aspects which as you indicate is not too bad. This 9"x7"x3/8", 36" long tube cost me $120 and although this was an off size and needed to be ordered via post, the standard sizes (ie - 8"x6") are typically available at your local metal suppliers for pickup. Compare this to the largest available size of alum profile from misumi of 200x100mm at a cost of $302. Another 'hidden' benefit of using rectangular tube is that I was able to tuck the y-axis motor, limit switches, and cable routing from the z-axis inside the tube which makes for a clean look on the gantry.

    Bought a lathe, ya..., along with EVERYTHING else in my new shop. I started with a drill press, looked around the basement filled mostly with storage boxes and thought, "Gee, I could build something down here". This router project was simply a reason to buy new toys



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    Default Re: Fixed Gantry Steel, wadeodesign

    This is a great resource for the DIY community! Thank you soo much for taking time to carefully catalog your build and sharing your experiences along the way! Very helpful for those in the planning phase as to what to expect to pay for parts and timelines.

    How did you go about sizing the gantry beam? Was this a case of 'feel' that it would be strong enough or was there some data/calculations behind your sizing? I guess bigger is better!

    Any videos of it cutting aluminum yet?

    I could see the design scaled to a larger size fairly easily, did you think about going larger? I am looking to build something with 48x48" cutting area. Hadn't really considered a fixed gantry build but the 'simplicity' of this one has me considering it.



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    Quote Originally Posted by CanonGuy View Post
    This is a great resource for the DIY community! Thank you soo much for taking time to carefully catalog your build and sharing your experiences along the way! Very helpful for those in the planning phase as to what to expect to pay for parts and timelines.

    How did you go about sizing the gantry beam? Was this a case of 'feel' that it would be strong enough or was there some data/calculations behind your sizing? I guess bigger is better!

    Any videos of it cutting aluminum yet?

    I could see the design scaled to a larger size fairly easily, did you think about going larger? I am looking to build something with 48x48" cutting area. Hadn't really considered a fixed gantry build but the 'simplicity' of this one has me considering it.
    Thanks - glad it's helpful... wish I took more pics and some video... Maybe the next build.
    The main driver for the gantry beam size was the linear rail spacing which I wanted to maximize. After that it was based on perspective to the other components. The radii of the tube is quite large so I only got about 7.8" flat machined area from the 9" height of the tube. I did compare the moment of inertia of this beam to aluminum profiles and was surprised to see that the geometry as it relates to stiffness was nearly identical when comparing same outer size... Then of course you get 3x improvement when moving to steel. I'd only be concerned with strength if the machine fell off a truck on the highway... It's beefy.
    Cutting Alum - Well yes, but my stupidity resulted in two broken bits as I tried to helical mill with too large diameter mill .... I'm finishing up the limit/home switch assy this week and the next project is to machine all the holes in the alum fixture plate and get it hard anodized. I'll do this directly on the router so will take a video then and post (about 2 wks or so)
    48x48? - that's a big area. The gantry is no problem and I wish my basement door was larger which was my limiting factor. The table gets challenging as for every inch travel you'll nearly double the base length. My 48" base allows 30" travel (I cheat a bit by overhanging the table off the base at max stroke), so increasing to 48 travel requires a base about 80"! (With some more cheating). That's a lot of waisted base material. Ball screw size will also be a factor as wip / critical speed will drive larger diameter screw and hardware, then more space between interfaces of linear rails.... And in the end may make this design the wrong approach and start sacrificing the simplicity of it.
    My gut feel is this design can go about 36 x 36 without too much modification, but price will jump.

    Cheers

    Last edited by wado1971; 12-07-2015 at 08:41 PM.


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    Default

    Quote Originally Posted by aarggh View Post
    If your cutting aluminium mainly, your table would lend itself nicely to build a containing wall around the outside so you could use flood coolant. This would maximise cutter life as well as clear the swarf so less re-cutting.

    That's what I'm planning for the machine I'll be building down the track, cleaning up after aluminium cutting on the wood CNC machine is a PITA.

    cheers, Ian
    Well I haven't considered flood but do realize after some first cuts that I must address cleanup asap. You've got me thinking now. Do you have any examples you can point me to? Does anyone use a dust shoe successfully with alum either dry or with mist?



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    Default Re: Fixed Gantry Steel, wadeodesign

    You could probably forget using a dust shoe if it's Aussie aluminium, most is quite gummy as has been pointed out, and I can tell you it aint fun cleaning oily swarf off the dust shoe!

    The other thing to consider is the high risk of explosion if your machining aluminium dry, and using some form of dust extraction, EXTREMELY good earthing and anti-static ducting is mandatory.

    Look up thermite!



    I'll simply be building a 100mm or so high barrier around the outside of the frame, with drainage holes going to the pump reservoir, doesn't need to be anything fancy, just high enough to catch all the spray, and a decent filtration system so you catch all the swarf but the liquid drains out. If it was a mill, I'd build a screw into a sloping base to actually move all the swarf out to a bucket, with the liquid draining off prior.

    Either way, the novelty of cleaning up after alu wears off quick. So in my book, an easier more workable solution is the way to go.

    cheers, Ian

    It's a state of mind!


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    Default

    @aarggh - thanks for the info. I'll likely add interfaces for flood to the fixture plate.



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    Default Re: Fixed Gantry Steel, wadeodesign

    Great build thread and thanks for sharing! That's a great table as a base, I'll have to look into that.

    I'm a big fan of the Schneider/IMS Mdrives having used them in a professional setting. They are a super high quality drive; we run them at 80% of their rated torque curve and none of them have stalled out. Typically you want 100% oversizing to your application.

    Are you running the mdrive plus2's with the serviceable driver boards? If so, I would open one of them up and inspect the fretting compound that contacts the 4 frets of the actual stepper rotor to the circuit board - make sure that is on there thick. At near 100% holding torque you run a risk of arcing and burning out that circuit board. We went back and forth with schneider on this - they finally just made us a custom part number with a soldered fret. If you're not running near 100% capacities, this may not be an issue.

    They make an external encoder option -EE that allows for correction using an external linear encoder. It's not real time correction, but I wonder if that would work for a milling application - or if that correction might throw something off during milling. I wonder if you could use a linear encoder with an index instead of a homing switch as well. We used this option along with a magnetorestrictive absolute encoder to acquire position on startup. Worked very well.

    Are you wiring your limit switches to the mdrive directly or to the BOB? (I guess this depends on the I/O of your stepper as well).

    Again, great thread!



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    Default Re: Fixed Gantry Steel, wadeodesign

    Quote Originally Posted by UA_Iron View Post
    Great build thread and thanks for sharing! That's a great table as a base, I'll have to look into that.

    I'm a big fan of the Schneider/IMS Mdrives having used them in a professional setting. They are a super high quality drive; we run them at 80% of their rated torque curve and none of them have stalled out. Typically you want 100% oversizing to your application.

    Are you running the mdrive plus2's with the serviceable driver boards? If so, I would open one of them up and inspect the fretting compound that contacts the 4 frets of the actual stepper rotor to the circuit board - make sure that is on there thick. At near 100% holding torque you run a risk of arcing and burning out that circuit board. We went back and forth with schneider on this - they finally just made us a custom part number with a soldered fret. If you're not running near 100% capacities, this may not be an issue.

    They make an external encoder option -EE that allows for correction using an external linear encoder. It's not real time correction, but I wonder if that would work for a milling application - or if that correction might throw something off during milling. I wonder if you could use a linear encoder with an index instead of a homing switch as well. We used this option along with a magnetorestrictive absolute encoder to acquire position on startup. Worked very well.

    Are you wiring your limit switches to the mdrive directly or to the BOB? (I guess this depends on the I/O of your stepper as well).

    Again, great thread!
    Thanks for the post... it was the motivation I needed to get going on motor tuning which I started this weekend. I'm using the MDrive Plus (not plus2) MDM1CSZ23C7 Nema 23 triple length stepper without encoder option. I got these guys used on ebay because at the time wasn't sure if I'd go servo or stepper so thought these would give me a good intro without the investment in separate drivers. At 35 bucks each it was a deal but had to purchase the Schneider comm cable for $125 to change settings. They are used... so I'm a bit nervous they won't perform once I get them going - we'll see. Edit: had a distributor quote this exact model stepper .. $282 (and adding encoder was $383).

    I'm running them at 1800 RPM, 2 microstep and this gives me 190 IPM on my X and Y axis which are running nice and smooth. I've got the run current (MRC) set at 90% and hold current (MHC) at 60% - no idea if these values are ok. I simply set the hold current so that I cannot manually turn the ballscrew by hand and can't see any performance difference when changing the run current so figured 90% was ok. No idea what hold current delay time (HCDT) is for but have it at 500 ms. Good to hear they're good quality but one major drawback to this brand is the lack of hobbyist and forum info so I'm running a bit blind in the setup - any input in my setup would be great but you'll need to dumb it down for this mechanical guy.

    The Z axis is a different story and I can't seem to increase above 40 IPM without inducing resonance and missed steps. The spindle is heavy and although a spring load for antibacklash helped a bit I'm considering offloading the mass with either an external spring or air cylinders. Not sure if I'll need > 40 IPM on z but it seems way too slow.

    I've just finished wiring the limit/home switches and have them to the BOB at this time. Is going to the stepper directly a better approach? And as for adding external encoder.... sounds interesting but at this time I'm just happy the electronics are working and I'm still alive - I will NOT be posting a picture of my electronics - lots to learn on this front.

    Cheers and thanks for the info

    Last edited by wado1971; 12-15-2015 at 08:21 AM.


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    Default Re: Fixed Gantry Steel, wadeodesign

    Quote Originally Posted by wado1971 View Post
    Thanks for the post... it was the motivation I needed to get going on motor tuning which I started this weekend. I'm using the MDrive Plus (not plus2) MDM1CSZ23C7 Nema 23 triple length stepper without encoder option. I got these guys used on ebay because at the time wasn't sure if I'd go servo or stepper so thought these would give me a good intro without the investment in separate drivers. At 15 bucks each it was a deal but had to purchase the Schneider comm cable for $125 to change settings. They are used... so I'm a bit nervous they won't perform once I get them going - we'll see.
    $15 a pop is a bargain for these motors - even used. I found a few of the cables laying around my work and grabbed them so I have a few at home. There are even different series of cables that are compatible with different motors (ugh). As far as life expectancy goes, I have only failures on these motors due to the fretting issue I spoke about in the previous post. Schneider eventually agreed to change their application process of the fretting compound. We ran an extensive reliability program on these assemblies and drove them hard.

    For most people, this is not an issue though. If you are interested in checking this feature, I can open up a motor for you and snap some pictures of the locations I am talking about. I used the Mdrive plus2 series, so the configuration may be different. I think you probably have a reliable system either way - and at $15/pop pick up a couple spares?


    Quote Originally Posted by wado1971 View Post
    I'm running them at 1800 RPM, 2 microstep and this gives me 190 IPM on my X and Y axis which are running nice and smooth.
    1800RPM is very fast. The torque drops off considerable at this RPM (see picture).


    How about gearing it up 1:2 and running at 900RPM and getting at least 2X the torque? Your lead screw of 12-02 - that's 2mm/rotation? That's killing your rapid movements. You could even gear it up 4:1 or 5:1 to be honest.

    I would approach this by gearing up, and setting microstep resolution to some integer value corresponding with your lead. 2mm/rotation and 4mm/rotation correspond well with your 1/2 microstepping, but 1/2 microstepping leaves you subject to resonance points within the 0-1800 RPM range, and I imagine that at some point you will experience these resonance point.

    I suggest an alternative approach: set microstepping resolution to as high as your BOB can tolerate on the output side. The literature states that the following resolutions are settable:
    200, 400, 800, 1000, 1600, 2000, 3200, 5000, 6400, 10000, 12800, 20000, 25000, 25600, 40000,
    50000, 51200, 36000 (0.01 deg/μstep), 21600 (1 arc minute/μstep), 25400 (0.001 mm/μstep)

    We ran our Z-axis at 51200 μstep/revolution on a 20mm diameter ballscrew with 20mm/rotation pitch driving 30lbs against gravity at 14in/sec or 840IPM. We were able to resolve position within ~3μstep or our intended position. I wouldn't worry about losing resolution gearing up or losing torque microstepping so aggressively. These motors do not deviate from the torque curve with higher microstepping settings - why? Because they have an awesome driver in them. Our repeatability for the 20mm rolled ball screw was within ±5um - the motors are super repeatable.

    Quote Originally Posted by wado1971 View Post
    I've got the run current (MRC) set at 90% and hold current (MHC) at 60% - no idea if these values are ok. I simply set the hold current so that I cannot manually turn the ballscrew by hand and can't see any performance difference when changing the run current so figured 90% was ok. No idea what hold current delay time (HCDT) is for but have it at 500 ms. Good to hear they're good quality but one major drawback to this brand is the lack of hobbyist and forum info so I'm running a bit blind in the setup - any input in my setup would be great but you'll need to dumb it down for this mechanical guy.
    Run current and hold current look great - even the way you set hold current is appropriate - you just want it to not move while other operations are happening (and it is always configurable if you find it doesn't work later). 60% is a good number, best to keep hold current as low as possible to keep motor temperature down, and also increasing the life of the fretting compound. HCDT I believe is the transition time from run current to hold current - I'll have to reference the programmers guide to confirm.


    Quote Originally Posted by wado1971 View Post
    The Z axis is a different story and I can't seem to increase above 40 IPM without inducing resonance and missed steps. The spindle is heavy and although a spring load for antibacklash helped a bit I'm considering offloading the mass with either an external spring or air cylinders. Not sure if I'll need > 40 IPM on z but it seems way too slow.

    I've just finished wiring the limit/home switches and have them to the BOB at this time. Is going to the stepper directly a better approach? And as for adding external encoder.... sounds interesting but at this time I'm just happy the electronics are working and I'm still alive - I will NOT be posting a picture of my electronics - lots to learn on this front.

    Cheers and thanks for the info
    The Z-axis has a couple things going against it - mainly gravity [hah] and the pitch of the ballscrew. This is why I suggest gearing up if possible.

    You are right to wire the limits/home switches to the BOB. If you didn't, then you'd want to run an output from the mdrive I/O to the BOB if the limit was triggered, and you'd have to go into the Mcode and write the functionality for what happens when you hit a limit switch.

    If you ever are interested in using an external encoder, I will gladly send you an Mdrive with the -EE option free of charge. Unfortunately, they are the RS422 communication ones MDI model and not the MDM model. You couldn't use it for coordinated motion. A lot of the Parker stages equipped with Mdrives use the external encoder option, in fact, there's a lot on ebay:
    12" Parker 404XR Linear Actuator XY Stage IMS MDRIVE17 Stepper Motors CNC DIY | eBay



    It's awesome that you went the mdrive route and tackled the whole mcode functionality yourself! They are stout motors with great accuracy and repeatability! You are correct in that there is a not a forum/DIY following for the motors. I think the initial learning curve of the Mcode and programmable motion is steep for people. Switches that control parameters are easier, learning an extremely simple pseudo-code in a text file format is more challenging for sure. Support for the motors is largely on the resellers of the Mdrives too - though I have called schneider/IMS motion and spoke with their application engineers regarding applications.

    Maybe this would be a good thread to post Mcode text files if you're willing to share. I would love to look over what you have. A disclaimer, I never actually wrote the Mcode functionality, I am a mechanical guy like yourself and worked with software engineers to program the code, and have poked around in the Mcode, but never did a full execution myself.

    Attached Thumbnails Attached Thumbnails Fixed Gantry Steel, wadeodesign-triplestack-png  


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    Default Re: Fixed Gantry Steel, wadeodesign

    Well I haven't considered flood but do realize after some first cuts that I must address cleanup asap. You've got me thinking now. Do you have any examples you can point me to? Does anyone use a dust shoe successfully with alum either dry or with mist?
    I use a fog buster for aluminum cutting with kool mist coolant. It works pretty well and beats standing there with a WD-40 can and air blowing the machine every 10 seconds.. Flood works better on drill holes or deep narrow pockets but a flood system with decent pressure is going to be way to messy without full enclosure.



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    Default Re: Fixed Gantry Steel, wadeodesign

    Quote Originally Posted by UA_Iron View Post
    1800RPM is very fast. The torque drops off considerable at this RPM ..... I suggest an alternative approach: set microstepping resolution to as high as your BOB can tolerate on the output side.... I wouldn't worry about losing resolution gearing up or losing torque microstepping so aggressively. These motors do not deviate from the torque curve with higher microstepping settings - why? Because they have an awesome driver in them...
    Thanks for the suggestions UA_Iron... Here's a partial reply... I'm starting to get a feel for tuning these things and will likely wrap it up this weekend.

    I played around with the z axis this week. Borrowed some extension springs from work and rigged up an adjustable connection to offload some of the #20 of the spindle. See pic... and yes that's a luggage scale - very professional
    To clarify things my z axis has a 2mm pitch leadscrew driven with the Nema 23 239 oz_in stepper thru a 22:26 pulley ratio. The highest speed before stall without spring was 45 IPM which I then reduced to 36 IPM (always go 80% from stall speed).
    By adding the springs to offload ~#10 I was able to squeeze 65 IPM out of her... And then by increasing microsteps to 16 (was 2), as UA_Iron suggested, in combination with spring I was able to get 100 IPM. Reducing this to 80% (80 IPM) for rapids will now fall in line with my expectations for the z axis. I was real nervous to increase microstepping as I read a lot of literature stating torque falls off drastically but you were absolutely correct about these motors and a short conversation with Schneider confirmed your statement that these guys don't fall off the curve. The z axis is running great without any hint of resonance now.

    So now I'll move onto the x,y axis and increase microstepping and see if some improvement can be had. In doing this should I be attaching a simulated load to the axis representing the maximum cutting force I expect to encounter and then tune the motors?

    As for gearing up. I currently have a 24:36 ratio on x,y with the 4mm lead. The 190 IPM on the x and y axis is rapids only, also 80% of max before stall (240 IPM is max), and I'll be targeting about 1350 RPM or 143 IPM for max cutting feed as that looks to be a drop point in the torque speed graph for this motor. This seems to be within the ranges output by gwizard for feeds when cutting aluminum with my spindle speeds - keep in mind this build was primarily for aluminum. For wood I could certainly feed faster and if doing lots of jobs in this medium I may consider swapping pulley ratio as u suggested to up my max feed rates but I'll soon reach my ball screw critical speed limit of ~2200 RPM so this machine will max at ~350 IPM without a change in ball screw diameter. I'll re-evaluate the gearing once I get a feel for performance of current setup while cutting.

    Quote Originally Posted by UA_Iron View Post
    If you ever are interested in using an external encoder.... It's awesome that you went the mdrive route and tackled the whole mcode functionality yourself! ...
    Thanks for the offer and I may take you up on this in the future but for now I want to get this machine cutting - and if you ever need an MDM cable you know were to look. As for the mcode - I didn't actually take this route as schneider provides a nice GUI for setting perimeters with the supplied comm cable which makes setup quick and easy.

    Cheers - wado .... will likely give a final update with more details with a blog post on the website - will link in this thread when complete.

    Attached Thumbnails Attached Thumbnails Fixed Gantry Steel, wadeodesign-img_20151215_200729368-jpg  


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    Default Re: Fixed Gantry Steel, wadeodesign

    I found a z-axis motor that would work well for you

    IMS Schneider MDM1MSZ42B2 EX MDRIVE42AC Plus Microstepping | eBay



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    @ gilmax... Thanks for the tip. I do have a mist unit kicking around so will give that a try.

    @ UA-Iron... Well that would certainly move the axis... Probably straight thru the table if it passed the limit... It's enormous at 11" long and 9kg. I'll stick to my little 23 for the moment. Cheers.



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