oky i did a test roadrunner with out routor on it seemed to run around in small erea but iam getting there and thanks jonny for heading me in right direction and putting up with my silly ? shure i.ll have more lol

 

no problem mate, glad i could help

 

oky update got thangs working had loses wheels on bottom checked every thang now it moves side to side forward and back wards up and down now to try to learn how zero my machine any help on this would be great .o and i had to tune x motor to 1800 it was 2000 steps

 

Hi all
I'm very impressed with this build. I'm thinking of getting back in to cnc routers after a gap of 27 years and it looks like things have moved on! What I would like know is what sort of power does this machine have in relation to driving a router cutter (1/2 inch) through mdf , to what depth, and what sort of feed rate. Picking up an earlier thread on the size limits ( the 8' x 4' question ) this wouldn't be practical on a belt system would it? Finally what would the maximum x y dimensions be I'm interested in cutting 18 mm mdf to form panels (trimming after rough cut would be fine)
Look forward to hearing
Thanks Martin

 

Hi Martin, welcome aboard and back to the hobby/profession/obsession.

The easiest answer is that it can be as big and powerful as you want it to be. Now, don't that sound like a dodge. I've built the belt driven machines that were as big a 1 meter by 1.5 meters. Then I realized that the mass of the router (old and heavy 3 1/2hp 1/2" Porter cable) was just too much if I tried moving the gantry very quickly. There was just too much give in the belts. Reducing it to 750mm wide and 1 meter long made the use with the router a viable and reliable machine.

Since this was too narrow for all my needs (which sound like yours) I decided to build a machine that was 36"x36" which gave me this;




3'x3' spoil board with 1.5kw 3ph water cooled spindle, acme 5 start screws driven by nema 23 425 ozin steppers for directional power and linear bearings and fully supported rails in each direction. The gantry is built up from 2 - 3"x3" series 15 8020 heavy extrusions and 1/2" side plates - it will handle any load I might ever hang on it. I can't even lift the gantry without the motor on it.

I could cut 1/2" mdf in one pass if there was ever a reason to do so - I'm not sure about feed rates to do it, but it would be possible.

As always YMMV.
Larry

 

Hi Martin, I think the use of belts should be no problem on 1 x 1.5 meter if you go for the double belt option, making a sort of rack and pinion out of them. It works great on my machine and some others are using it also (I believe with satisfaction but better check it with them). Martin Barfoed has an excellent video about how to do the double belts.
If you want to go bigger than 1 x 1.5 meter you more likely to run into other problems such as flex of the profiles and general stiffness of the build.

 

Can I add practicality is also an issue.

For instance I have an 8x4 machine that is ballscrew and rack and pinion and is capable of 6m/min Rapids in both x and y and 18mm doc @3m/min if I'm not looking for a finish.

Now i can point you to a file opensourcebeehives.net Barcelona ware hive under source files. This job takes just shy of 8 hours to cut to a 0.25mm tolerance with finished edges using a doc of 7mm @ 3.6m/min.

So would take considerably longer with a less capable machine.

Don't get me wrong the ox is excellent in smaller formats, I use mine for most of my small parts.

 

Martin - is there a reason you are looking at the Ox? If you need a 4x8 machine, I guess the answer would be no, don't go there, but there's at least one person I know well who that uses a 12' long belt drive machine (my wife's quilting machine. That moves a heavy head (+60lbs) and has no problem.

 

Hi all again
Thanks for all the responses. I'm looking to get into cnc and recognise that the ox seems simple and above all achievable. I will probably build this purely for learning and try a variety of control combinations. Before deciding what I truly want. I was asking about the power because I don't know what any stepper motor spec means or more precisely how it translates into the force at a cutting head, so was speculating if I made the ox to its largest size what it could actually cut. If it can't cut sheet material practicably then I think I will make the smallest version so I still would like to know what sort of cut can be made with the ox spec as constructed in the open build videos, can you stop it moving with your hand?. I also have an eye on the fact that the ox could perhaps make components for a larger machine.
Thanks
Martin
(V. Impressed with your build star geezer)

 

Thanks Martin. A couple notes about stepper motors might be a good start then. First of all you need to understand that stepper motors generate and are rated by their holding power, not the rotational power we think of with traditional motors. So when I state that my steppers are rated at 425 ozin, that is the force they will resist rotating when energized. CNC routers energize the steppers as soon as the power is turned on. When stepper motors begin to move they begin to act more like traditional motors except they can only be powered to rotate 1.8 degrees per signal or step from the controller and driver.

So when you ask if you can stop the gantry from moving with your hand, this was what I meant by "it depends". I can clearly state that a Ox with Nema 23 steppers, 180 ozin can be forced to rotate out of position by hand, but it requires a lot of force. If the gantry is being told to make a move and you try to stop it with your hands, you might do it, but brace yourself.

The bigger machine I showed is equipped with 425 ozin steppers driving 5 start screws - never try to stop a machine like this - it will break your arm.

Here's my Ox;



I can barely force the gantry out of a stopped position. When moving it is possible to make it skip.

I would avoid nema 17 steppers. they will work for a Ox, but they really can be pushed around very easily. Nema 34 steppers are over kill IMO until you start talking about that 4x8 table with big lead screws, 25mm (or bigger) linear rails and steel where a Ox is Aluminum. On the Ox shown above I'm using a mix of steppers. 23's on the x and y axis and a 17 on the z axis. that 17 is ok because it's driving a 8mm single thread screw and the power curve of the stepper is just right for this exact application - like the nema 23 425ozin steppers on my bigger machine are just right for that application. Steppers hooked to screws always have a huge mechanical advantage over belts.

I hope I answered some of your questions, if not I'll try to be more specific.

Larry

 

Excuse me if this was mentionned before, but the part list calls for a Z axis made of a 20x40 rail : "V-Slot 20x40mm (1500) Center Table support (710) Back Brace (500) Z axis (180)", while in pictures and videos it is a 20x60 rail.

Edit: Never mind, both are possible, just saw that part on the video.

 

oky iam back iam looking to get mach3 right now iam doing the free version to learn it .what do i need to start designing and than put it in g-code to use mach3

 

You are going to need a cad program for design and then a cam program to generate the g code. Mach 3 has Lazycam built into it. BUT sadly it's about the worse there is. I use Vectric Aspire for cam and also rudimentary cad. It's not cheap but it's easy to use. Sketchup is a free cad program many use and think highly of. There are currently several free cad packages out right now some simple and some you need to have a degree to understand. I use Corel Cad because I learned Autocad years ago and all the Autocad commands work with Corel Cad.

Just yell if you get lost in which is which. Believe it or not, now the learning curve gets really steep.

 

Then you could add gearing, I have two 3.1nm on planatary gearboxes outputting 48nm @20:1 reduction. Obviously your not likely to get that unless it's direct onto a lead/ball screw the same diameter of the shaft, so you going to be gearing it back up somewhat but these two are shifting 270 odd kg's at 6m/min so

Point being gearing can improve torque. 48nm with belts would most likely be counterproductive, you probably get stretch and vwheels pinging off. So it's finding a balance.

3nm is the limit with gt3 imo. But you could achieve this with nema 17's with a 5:1 - 10:1 reduction.

 

is this what i need for coral cad stargeezer http://www.ebay.com/itm/Brand-New-C...Auth-Dealer-/390762825645?hash=item5afb4787ad

 

Can I suggest trying onshape cad and using fusion360 for cam. All completely free.

 

I really wouldn't bother with Corel, everytime I come across Corel dxf files they are problematic

 

That is what I'm using, but I'm a dinosaur. If I were starting out fresh today, I'd learn the two Jonny recommended. It's great they are free and I have looked at them and the only reason I'm using Corel Cad is that it's command structure is so like the Autocad I learned back in the nineties.

 

Part of the problem most people have with it is not saving the files in true AutoCAD format. The save function goes to Corel's interpretation of a dxf file. This was largely fixed with the 2015 version, but some folks just hit save and don't look at what the screen says.

 

Could well be the issue. Mostly find broken vectors and overlapping duplicate lines over each other. Basically have to retrace them onto a new sketch to use them.

Though they may work with aspire or vcarve etc. that software is amazingly unfussy. Try to use them to create 3d parts in inventor or solidworks for hsm 3d strategies is a different story.

 

sure thang johnny will get them and thank s

 

Jonny - That sounds more like poor drawing skills to me. It's easy to get those in any CAD program, but a good draftsman keeps them cleaned up.

As for being "unfussy", that's what I like in software. Just do it and don't give me any grief. It does sound like your needs are far greater than mine. I was a old school manual draftsman who was working in the field through AutoCAD 12, at which time I started another path.

 

Lol yes drafting skill does help.

That join open vectors function is fantastic, it crazy I use solidcam and inventor, both are able to doctor sketches. But both not only being fussy take a while to complete, yes compared to vectric software it attempts to fix constraints and cleans redundant point amongst other things so ultimately makes for better drafted vectors which is why it takes longer. this is only really required if you wish to make changes to the sketch otherwise all your after for Cnc is closed vectors.

But they fail if they are unable to complete any part of this more refined process. Which seems to be 50% of the time.

If I'm just looking for unannotated closed vectors, instead of enduring the doctoring process, I now open in vcarve, close the vectors and export to inventor or solidworks instead.

So much quicker. And it seems to export the vectors without breaking them into both platforms more reliably than any of the pro platforms.

On occasion even vcarve fails. I'd say only 5-10% of drawings I received contain closed vectors.

Yet to understand why most Cnc routing companies insist on drawings.
Much quicker from 3d. Click a face and export as dxf if you need to. no need to proof the operations. The model doesn't lie

 

So, what do you do after spending hours/days/weeks on a design that is stored and made in the cloud and the cloud evaporates? You know, clouds can disappear in a blue sky? Or what do you do if the people of Onshape or Fusion360 decide to start charging you a considerable fee for the use of "their" cloud and without paying it, you will have no longer access to your work? Nothing is truly for free, read the little print.

If you know how to use it properly, SU is an excellent free 3D tool (with software and data stored on your own computer!) and in combination with Vectric Aspire or VCarve (also with software and data stored on your own computer!) very powerful in making anything you would like to. Aspire V8.0 etc. now also can import SU files and make them straight ready for cutting on the CNC.

I wouldn't waste my time on learning to work with software or "solutions" that can be gone like "phooooffff". And yes, in 5 years you may quote me.

 

Sketch up is gimic software, it generates the worst vectors of all cad programs, with not only broken vectors but dimensional errors also. I have had to redraft many all of which if I sent straight to cam would have either failed to produce toolpaths or simply not gone together. Maybe okay for making shapes once you have repaired the vectors but for stuff with tight tolerances your cutting that lovely expensive material you've purchased with something that is free because it is doesn't meet the standards of a paid piece of software.

Onshape does have a function to download your files and store locally which if you plan on importing them into 360 you need to do anyway. Onshape are obviously in tune to the fact that no buisness buys cad without a trial, so onshape simply allow a free trial account that enables you to save up to 5 projects free, any serious companies will require more and need to purchase a full account. There is no mention that a beta account will expire and it would be pretty bad publicity if they did, so get one while you can.

Auto desk who can afford expensive advertising and public relation campaigns has only recently added a basic hsm version to fusion 360 to support the non profit maker community. They are not likely to start charging for it anytime soon. Like onshape you can keep your files local if you wish. And is a pretty powerful piece of cad design software also.

Vectric software is Excellent and is needed or a similar alternative for all your 2d work. But standalone you will be only be creating 2d toolpaths. You ideally need a cam capable of 3d strategies along side it. But for learning cam best place to start is with 3d cam package that's going to give you the chip load, preloaded tools and a real time simulation so you can see where each variable makes changes. Once you have mastered 3d then something like vectric will have very little learning curve to it.

 

The nice thing about the "free" software packages is that they allow a total noob to get started without breaking the bank on something that might not even work for them. Heaven knows I've got a short stack of software that wasn't quite what I thought it was when I bought it and most anybody who's been messing with computers for the past 40 years does too.

I bought a couple low end CAM packages trying to find a cheap, easy to use software before I stumbled onto Vectric software. I really had not understood that you needed several different pieces just to make a machine move. I'm certainly not stupid, but the full understanding of what was required was not understood when I decided to add CNC's to my already well equipped woodshop. To add the price of multiple software packages to the price of the hardware was a tough swallow. It's not cheap. After the initial sticker shock I tried finding a less expensive route, but each one left something out I felt I needed or handled the workspace in a way that was not efficient for me. It was a big reason I purchased Vectric's low end package Cut2D first - and I bought it only because they had the upgrade policy that they offer. Which I took advantage of going to Aspire - the absolute best move I made. I've not yet found anything I needed to do that I could not with it.

I should add that this is all a retirement hobby for me. If I were trying to make a living with my woodworking I'd be in trouble.

 

It's a hard game Cnc, need to run them 8 hours a day 5 days a week to make money, and it can all go down the pan in a matter of a second.

 

well i was going to try to do fuison360 but its free for 30 days but now i thank iam going with sketchup make for cad and cambam for cam and than i can still use mach3 and i dont mind spending $100 to $200 .do to me still learning CNC. iam trying to start a guitar design now but thank i will have to get guitar templete to paste in sketchupmake cant seem to do it with the tools . i spent most of the day looking at programs and watched youtube videos. i will figure this out . and you guys in this forum are great help and thanks

 

You have to go through the education link unless you think you qualify as a profit organisation, personally I would say your learning and therefore a student.

http://www.autodesk.com/education/free-software/fusion-360

 

Oky nother ? i found some free fender DXF prints on line now when i click them they go to Adobe reader file and wont load in the sketchup make any help ?