For everyone out there that is using sketchup to design, what is your workflow to go from a design in sketchup to cutting on the ox?

 

Sketchup -> SketchUcam -> Mach3

 

Thanks I hadn't looked at SketchUcam yet, will check it out!

 

I just found a skp to dxf free converter that seems to work with the free version of sketchup...

http://sketchupplugins.com/plugins/convert-sketchup-skp-files-to-dxf-or-stl/

To install it, you need to open Sketchup, click Window/Preferences/Install Extrension then browse to your download folder and click the skp_to_dxf.rbz file.

To use: click File/Export to DXF or STL

Dimensions seem correct after export, unlike other exporters we have tried.

Chris

 

Hello All! This is my first post here. I was searching for a CNC router and I was prepared to spend a small fortune untill I found Openbuild OX. I have a simple question...Which axis is X? Is it between the gantry plates or along the main rails? Reason I ask is to help me understand the OX BoM spreadsheet. Thanks

 

I think typically people refer to the side to side between the plates as the X axis, front to back as the Y and up and down Z of course.

 

I got the same message sometime even if the port was well configured (on WIN7 ).
What I found is that connecting the USB to the xPro BEFORE switching on the PSU, makes the trick.
The test bench is based on a 24V PSU, CNC xPRO, 3 NEMA23, and a dedicated controller for a small brushless motor to simulate a BL 700KV spindle.
The process I'm following is: 1) PC on, 2) usb connection, 3) GRBL controller on and connected, 4) PSU on.
It connects every time. May be worth to try it.

Still in the process of building the OX, so I don't know what will happen when everything will be connected instead of being on my desk, though.

 

Just got my shipment of remaining parts from the Openbuilds parts store. I have to commend the guys there for their meticulous packaging every time to ensure that our parts go unharmed during shipping. Thanks for everything!

 

Thank You guys for helping with the info. I already purchased my plates and will be ordering machine parts soon, CAN'T WAIT!

 

I've been lurking here a while, even before signing up for the forum... I was considering buying a Shapeoko 2, then I considered buying a cheap Chinese CNC to learn on... Eventually I decided that it would be better to build the Ox and learn about the CNC machine inside out, have a larger cutting area, etc. I'm getting ready to buy all the parts in the build list, but I have two questions:

1) In the build/parts list, "Ox Plates" are listed twice. Do I need two sets of plates, is this a typo, or are there two different sets of Ox Plates needed for this build?

2) Is there a router mount made for a DeWalt or some similar tool?

Thanks in advance, can't wait to order the parts and get this thing put together...

Jason

 

Nevermind on the second question... The same guy making the Ox Plates and selling them on eBay, Chris Laidlaw, also makes router mounts for it...

 

I am struggling with the electronics, settings, and calibration. I have to clear an alarm every time I plug it in. then it moves okay but the alarm is there every time I bring it back online. I also have to set a feed rate (I just put in F100). Thoughts?

My main concern is when I did the calculations for my CNC parts (used everything listed in the build parts list) I am getting values that are not producing reality dimensions.

Example. When I design a 1" x 1" square it doesn't come out one inch. It is undersized. I can adjust my # steps/mm but then it throws off my machine numbers in GRBL Controller.

Also the accuracy of cut is poor. I have not yet squared up my spindle to the table yet. Any links on proper steps to increase the accuracy of the machine?

 

i can confirm the same. all the holes on the plates needed adjustments. and i was actually missing the Z axis slide :-D

anyway, it was sorted out, i just had to wait 1.5 months for the missing stuff to arrive.

i had no issues with the eccentric spacers, but i received ordinary washers instead of shims. to move forward faster i bought some from fabory (european fastener wholesale). then i had to re cut the v-slot slides as there were differences up to 0.8mm in length, and the cutting angle was not 90 degree. fortunatelly i found a local guy with a pretty decent "homebuilt" cnc and he adjusted them for me for just 4$ worth of local currency.

but after all i'm still happy.

so, lessons learnt: order the kit minus the plates. get a local cnc guy to cut the plates. ask him to adjust the slides as well. btw, meanwhile i found some eBay sellers to sell the ox plates on a very reasonable price.

 

Meanwhile I have received everything that I missed. Reading the previous message I realized that I probably also got plain washers instead of shims, but I think the accuracy is only _really_ relevant inside the wheels, and there I have shims.

Anyway, new question: I have started wiring all the electronics and now it is time to get the two nema's 23 that share one axis to work together. From the net I found that I have to wire a nema23 black-green-blue-red but if I do that with both motors, they will rotate the same direction and since they are in opposite direction mounted, they are each going in a different direction. I figured that if I swap the connections at each coil (so: green-black-red-blue) it would reverse, but it won't work properly. Actually I am not entirely sure that the motors are each going in one direction, as it does move, but with hiccups. I would almost think there is another reason the two motors do not want to cooperate nicely. Anyone some thoughts on this?

 

Hck, Iwas thinking about the same issue with running the 2 motors on the same driver in opposite directions. I run our plasma table at the school I teach at, but it doesen't run on Mach3, it is a Dynatorch plasma table. I was poking arround in the setup screen and I found one item that states " opposite y = slave" I'm not sure if this means anything in your setup, but i thought i would throw in my 2 cents.

 

[/QUOTE]Anyway, new question: I have started wiring all the electronics and now it is time to get the two nema's 23 that share one axis to work together. From the net I found that I have to wire a nema23 black-green-blue-red but if I do that with both motors, they will rotate the same direction and since they are in opposite direction mounted, they are each going in a different direction. I figured that if I swap the connections at each coil (so: green-black-red-blue) it would reverse, but it won't work properly. Actually I am not entirely sure that the motors are each going in one direction, as it does move, but with hiccups. I would almost think there is another reason the two motors do not want to cooperate nicely. Anyone some thoughts on this?[/QUOTE]


it is only necessary to reverse one pair of wires. so in the above example of black-green-blue-red, the opposing motor should be wired black-green-red-blue. Its in the build video's I think its the second one.

 

@hck,
I'm still building up mine, so please take what I'm saying as "to be verified".
What I understood is that to reverse the motor direction, we should swap JUST ONE of the coil, so I would check a connection like green-black-blue-red.

EDIT: David beat me by few seconds

 

Am I reading this right that the CNC xPRO CONTROLLER STEPPER DRIVER http://openbuildspartstore.com/cnc-xpro-controller-stepper-driver/ drives the motors and controls the cnc. Im new to this and from the video it seemed that you needed two boards? HELP im a noobie

Also can you use Mach3 with the driver instead of grbl

 

You can use the cnc xpro, or tinyg, or grblshield, or gecko drivers, or many of the other stepper motor drivers out there. To my knowledge, Mach3 only works with printer port based drivers.

 

well, not really. on the x axis you have double shims between the wheels to keep them parallel and to have them both running in the v-slot groove. this was the point i realised that the washers are not precise enough.

regarding the steppers: i was all the time concerned about running 2 2.8A stepper from the same pololu driver, so i decided to have properly sized drivers for the nema23s, so i bought a TB6560 based stepper driver board. yes, the red chinese monster. first i thought a 3 axis version will be ok. then i realised, that i need another axis for the Z, as 2 steppers are running on Y. so i bought a single axis stepper (green) driver also from eBay. first i tried to run them from an ancient pc using PP. then i flashed grill 0.9 into an arduino nano, connected the io pins to the stepper driver board's parallel port, and it is running pretty good.
i just had to fork the y axis dir/step signal pins coming from the arduino to the 2 axis of the stepper board.
of course i can't mount this setup on the X beam anymore, so i added two drag chains to keep the wires organised,
and have the stepper controller/arduino/powersupply/vfd/whatever housed safely under the OX.

 

Got my gantry plates, computer and motion control. I will be placing my order for the remaining components from the store on the first of March. I'm going to build it 1000 mm x and 1500mm y. Man I'm excited!

 

So I have my ox up and running, still have a few things to get in order before I consider it "done".

I would like to ask those that have completed their builds how does your backlash look? I am having an issue and I'm not sure if it is backlash in the typical sense or another issue altogether. I setup a dial indicator and when changing directions it looks like there is on average about 10 thou of backlash. I'm not sure if it is purely mechanical or if there is something stepper/controller related as I found this after a brief google search and it is very similar to my issue: https://www.synthetos.com/topics/weird-inaccurate-first-move-after-homing/ I did update to the most current "tinyg-edge-438.02.hex" firmware as my tinyg was on "tinyg-master-380.08.hex" firmware version in hopes that this would fix the issue but it remains.

The reason I even looked at this, was because I thought I had my machine pretty well setup and ready to go, it appeared to be very accurate when using a ruler. I test cut a 5mm hole in aluminum and the hole turned out terrible, about a .5mm undersize and oval.

 

Regarding the last post, it *just* occurred to me that I should double check my pulleys on the stepper motor shafts. I may need to tighten them as I was being very cautious with them since they are so tiny and I'd hate to strip them out. I will check into it today.

 

How do most people use this machine? I'm curious to know what I can do with it besides cutting signs and flat plates plates. Can this be used as a milling machine to make aluminum parts like a mold for casting plastic resin parts or aluminum parts for a motorcycle? I know it would probably have to run pretty slow but that wouldn't really matter if you had a full time job and left it running while you are at the office.

 

Looks like my pulleys came loose. I'm happy to know that is the problem and not something more abstract. Going to file the side where the second set screw sits flats so it has a good bite and loctite the screws so they don't back out again.

Hopefully my OX will be super accurate now!

 

Couple of issues.

1. I still don't have accurate steps/inch to get reality measurements. What are peoples settings?
2. I have been dinking around with the steps/mm/inch settings and it started to lock up when I would power on the machine.
3. During the same time as problem two, when I enter a command. Example, jog it ten steps (10 inches) to the right it will move but cnc quits at like 5 inches and the GRBL controller still moves to 10"

Is the Xpro going bad? is that a thing? I am 100% new to this so please chime in. I am getting very frustrated with this build.