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CNC?

#1
I've built several kits so far and have gotten the itch to try some scratch building, namely hot wire foam cutting. My biggest concern was creating the cross sectional "tracers" for each section. My free hand cutting abilities are not quite to the point where I'd be satisfied with the accuracy of making the number and variety of "tracers"
(i can already feel the cramps)
I've always thought that CNC set-ups where well out of my budget but recently I came across kits for a CNC dremel(minus the dremel, which I already own) for around $200-300. I understand that you can build them for even cheaper if you do some part salvaging, such as getting stepper motors out of goodwill printers, etc. but was concerned with accuracy, and last I checked CNC laser set-ups where atleast twice that in cost. Do you guys have any recommendations for plans or kits for a CNC cutting set-up of some kind?

I am capable of reading and writing g-code due to my college courses and have some experience running CNC lathes, but was concerned in the axis control mechanism/software. That seemed to be one of the primary contributors to cost in any CNC rig.

I had planned on using thin(up to 1/4") balsa for the formers and eventually for other small projects here and there. Any advice would be appreciated. I am a recent graduate still on the hunt for a degree involved job so my budget is on the slim.
 
#3
My advice would be to wait a few more days: https://instagram.com/p/5a5rniimoX/
The Instructables X-Carve machine really is a pretty piece of equipment. It is quite reasonably priced as well, and I like that they let you configure it with as many or as little parts as you need. For example, if you already have steppers or a controller laying around you can use those and save some money.

CapnFailBoat:
It all depends on how skilled you are with setup and how much time you want to spend building it. If you can wait a month or so and you feel like experimenting, I'm working on a 3D printable CNC machine that can be scaled easily using different lengths of smooth rod like reprap. Should be significantly cheaper than the X-carve (though much less pretty)
 
#4
The instructable rigs look great but they're all well out of my price range.

I'm fine with any amount of set-up time, my biggest weakness is coding though, seeing all those arduino powered motion controllers got me real nervous during my search. The real reason behind this and the project planned that sparked the CNC cutter search was to keep my engineering skills sharp while I'm on the job hunt so the more set-up/experimentation the better. I'm just looking into a starting point really.

So far what i got is that i'll need
-a movement platform of somekind rails/belts for atleast 2 axis(with a fixed z axis plunge) prefferably 3 axis to include a variable plunge
-stepper motors
-a motion/axis controller
-a compiler of some kind or i'll be typing g-code by hand (had to do that for a project once, would rather not do it again)

The hang ups i'm having is that I have a pretty nill understanding on what i'd need out of a motion controller or the stepper motors or what i'd need to connect them all together. My major was in mechanical so i'm a bit vague on coding and even electronic components.
 
#5
The instructable rigs look great but they're all well out of my price range.

I'm fine with any amount of set-up time, my biggest weakness is coding though, seeing all those arduino powered motion controllers got me real nervous during my search. The real reason behind this and the project planned that sparked the CNC cutter search was to keep my engineering skills sharp while I'm on the job hunt so the more set-up/experimentation the better. I'm just looking into a starting point really.

So far what i got is that i'll need
-a movement platform of somekind rails/belts for atleast 2 axis(with a fixed z axis plunge) prefferably 3 axis to include a variable plunge
-stepper motors
-a motion/axis controller
-a compiler of some kind or i'll be typing g-code by hand (had to do that for a project once, would rather not do it again)

The hang ups i'm having is that I have a pretty nill understanding on what i'd need out of a motion controller or the stepper motors or what i'd need to connect them all together. My major was in mechanical so i'm a bit vague on coding and even electronic components.
Luckily the controller bits have been figured out already by open source projects. You can run the machine off of an arduino with some stepped drivers. You have to put a firmware like GRBL on the arduino and configure things like stepper configuration and end stops and stuff. G code is automatically generated by another open source program which is the. Loaded into another program that talks to the machine and tells it what to do.
 

pressalltheknobs

Posted a thousand or more times
#6
My advice.

Only build a CNC machine if you want to build a CNC machine. It's a fun and rewarding project if that is your passion. However a scratch built CNC machine is likely to be disappointing to start with and require a lot tweaking and cajoling to get it to produce reliable results which it may never do. And it will be much more expensive than you expect by the time you are done. Unless you are determined, most probably it will end up as a box of parts gathering dust.

... but...

if you want to build a hot wire cut foam plane either buy the guides or make them and just try it. Making a hot wire cutter is cheap and the foam is cheap, if you have a local build supply place that carries it. Getting the guides (formers) right is probably easier than you think, probably you don't need that many of them and they don't need to really super accurate or beautiful. They are just guides. Sandpaper and filler will compensate for any minor flaws.

Just a thought.
 
#7
I would agree with you if i knew that this one model would be all i used it for but when i had acess to a laser cutter i was using it several times a week just trying new things. I have a bit of a back log of ideas i want to try so it would stay active once it's up and running. As for difficulty/tinkering I'm all for it. As i said this whole project was meant to keep me technically engaged.
 

pressalltheknobs

Posted a thousand or more times
#9
I would agree with you if i knew that this one model would be all i used it for but when i had acess to a laser cutter i was using it several times a week just trying new things. I have a bit of a back log of ideas i want to try so it would stay active once it's up and running. As for difficulty/tinkering I'm all for it. As i said this whole project was meant to keep me technically engaged.

Well I think that qualifies and "wanting to build a CNC machine". Still, probably better to start with a kit than do a complete DIY if your goal is to have a working CNC machine in a reasonable amount of time.

This article looked interesting...

http://blog.ponoko.com/2011/07/15/pricing-guide-to-diy-cnc-mill-and-router-kits/
 
#12
Wow, thanks guys all those links look like a wealth of information. Those videos looks particularly interesting.

A big question I have now is that I keep seeing mach3 and GRBL and being called out. Am i under the correct understanding that mach3 is a hardware portion of the axis control and GRBL is a the software component?
 

jhitesma

Some guy in the desert
Mentor
#13
Mach3 and GRBL are both software components.

GRBL is what runs on the embedded system (arduino) that's part of the CNC machine itself. GRBL accepts Gcode as input and then actually talks to the motor controllers to make things move.

Mach3 is a CNC controller that runs on your PC - it feeds the Gcode to GRBL and allows you to do things like shuttle the carriages and control the machine without having to manually input Gcode commands.
 
#14
So Mach3 is more of a gcode generator and GRBL is the portion that recieves the resulting gcode and translates it into motion?

-edit- My previous experience with CNC has been either importing a draft file into SURFCam and then transfering the created gcode directly to the CNC lathe, or using Corel draw to create a file that was capable of being "printed" by the available CO2 laser cutter, it was litterally clicking the "print button" on the controlling computer.
 
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#15
So Mach3 is more of a gcode generator and GRBL is the portion that recieves the resulting gcode and translates it into motion?

-edit- My previous experience with CNC has been either importing a draft file into SURFCam and then transfering the created gcode directly to the CNC lathe, or using Corel draw to create a file that was capable of being "printed" by the available CO2 laser cutter, it was litterally clicking the "print button" on the controlling computer.
You're right about the GRBL, but Mach3 is more of a gcode transmitter than generator. I've never used Mach3, but if it is anything like pronterface on a 3d printer (which I believe it is), you use another program to actually generate the gcode from a 3d model. Correct me if I'm wrong.
 
#16
Ok just so i can get a clear idea on the process of cutting a design out, it goes something like

Create design in some kind of design/modeling software>Create g-code with somekind of interpreter> use software (universal g-code sender?) to send g-code to the physical grbl arduino shield which uses grbl software> arduino then tells the cutter how to move and cutting proccess begins

This video clarified a few things, was listed on the previous page i believe, https://www.youtube.com/watch?v=1ioctbN9JV8

I'm not familiar with the hex file type the video mentions when using the xloader software or entirely what the xloader software is doing.

I'm also a bit hung up when he uses a txt file to generate/send the g-code with the universal g-code sender software, i'm used to dealing with stl, dwg, and pdf file types when working on these type of machines
 
#17
The Shapeoko is popular.

But this one is the one I'm keeping my eye on.
It's built like a tank.
http://openbuildspartstore.com/c-beam-machine-mechanical-bundle/

20150709_101639__17004_1437062240_400_310.jpg

The "Openbuilds" and "Openbuildspartstore" sites are must reads for anyone contemplating a DIY CNC.

The Open Builds Website and Store was started by Mark and Trish Carew. They are a husband and wife team who set up a family business by offering a DIY foam cutting machine for fanfold foam called a PhlatPrinter. People bought PhlatPrinters for the express purpose of cutting out foamy RC Planes.

Now the Carew's have branched into CNC Parts with the creation of the OPEN BUILDS WEBSITE and PARTS STORE. The PARTS STORE sells linear drive systems which consists of custom aluminum extrusions, wheel systems, mounting plates, drive belts, linear drive screws(acme screws), stepper motors...and the list goes on.

The separate site called OPEN BUILDS is essentially a CNC Forum consisting of all sorts of projects using the aforementioned extruded rail and wheel systems.
http://www.openbuilds.com/

One of the interesting projects is the OX CNC MACHINE that can cut up to a 2'x4' footprint.
http://www.openbuilds.com/builds/openbuilds-ox-cnc-machine.341/.

341.jpg

Recently, some new extrusion, plates, and a bundled linear drive have been added to the store selection.

It would be neat if FliteTest could partner with the Carew's in the design of a new 2'x4' system using all the latest advances of available parts in the store.

The generalized requirement would be a tabletop machine with 2'x4' footprint that could cut "full sheets" of blue fan-fold foam, Model Plane Foam, Depron Foam, DollarTree Foam, Plywood, BassWood, Bulsa, Coraplast(Corrugated Plastic), F4, G10(QuadCopters), Carbon Sheet(Quads), Acrylic Sheet, and Lexan Sheet.

The Specific Offerings would be:
#1 - A Generalized 2'x4' Mechanical Kit where everything is included...no need to order parts individually.
#2 - A selection of Custom Holders for the various routers and/or spindles that can be driven.
#3 - A Stepper Motor Package of 3 Nema-23 Steppers.
#4 - A Controller Board.
#5 - A Power Supply.
#6 - A Leg Set and Shelf Package(to hold computer keyboard, laptop or tablet) constructed of extruded aluminum so that the machine could stand on it's own.

This machine would be more or less..."FliteTest Tested".
It would still be sold through the Open Builds Store.

Flite Test could add a specific category to the FliteTest Forums for all those who had purchased the machine.
Also, if a particular Controller Board and Software could be standardized...a library of free downloadable plans could be maintained on the FliteTest website.

If you could get a 2'x4' footprint DIY CNC Machine Kit, with the Mechanicals, Motors, Rotary Holder, Power Supply, Controller Board, free software, and an active forum of user support...all inclusive in the $1000-$1200 range...I think there may be some interest.
 
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#18
From everything I've been hearing and finding out it seems more and more like what I'm looking for is a basic kit that i can work my way to completion on. At the moment i can maybe spare $200 up front. I figure i can find some plans or a bare bones kit and get 1 or 2 components at a time
 
#20
I'm thinking a minimum work area of 6" x4" but of course bigger is better, but anything over 3' x 3' is pretty excessive for my current ideas.
 
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