Question for you CNC guys: buy or build (might have some free linear bearings)

[BadMouth]

The cheap 3D printer thread has rekindled my interest in having a desktop CNC machine.

A friend of mine has some linear bearings gathering dust.
They are this type:


They are the type that only has one row of bearings that rides in a groove rather than two rows riding on the outsides of a rail.
(one row of bearings top and bottom, rather than 4 rows keeping everything centered)
They are a good bit beefier than the ones in the pic.  They are much wider and have two rows of mounting holes.

IIRC, I worked out that I could have something like a 12x18 work area with what was there.

I'd like something that could handle aluminum, wood, & pcbs with reasonably professional results.

Would this type of bearing be good enough for that?
Is it worth messing with these vs just buying something like a Shapeoko kit?

I'm assuming I'd end up with a more substantial machine if built myself, but the quality of my work is far FAR from machinist grade so I could just end up wasting a bunch of material.
I do know a machinist that would cut a piece or two for me for free, but I'd feel bad asking him to do more than that.
He works at a factory and typically doesn't take any outside work.

[Nephasth]

12"x18"? Why even bother if it's not at least 48"x96"?

[Howard_Casto]

planetjay and I have been researching this for the better part of a decade. 

There isn't an easy answer to your question.  Basically the more you spend, the less hassle you'll have up to a certain point and any spending beyond that doesn't make any sense unless you want to do industrial grade stuff. 

In terms of cost, typically your stepper motors are the biggest part of the cost, followed by rails/rods/bearings, your frame, and finally the controller, which will cost you practically nothing if you go with a simple avr and motor controller setup. 

Nema 17s are what they use on 3d printers but the weight/size usually needs to be beefed up a bit for cnc.  He should still have a youtube playlist out there somewhere with the dozens of builds we looked after. 

In terms of assembly, the kits are fairly easy to assemble, but of course cost will be at a premium.  By far the cheapest method is to build the frame yourself and collect bearings/rails/ect separately, but that will probably require a bit more skill. 

[Typefighter01]

Putting the question of building your own from scratch aside, if you were going to give the Shapeoko kit a serious look, I would suggest looking into the OpenBuilds OX kit first http://www.smw3d.com/ox-diy-cnc-kit/.

There is just a massive online community of people building and upgrading these and when you stack the Shapeoko's $1000 against the OX's $1000, your getting alot more for your money with the OX (Nema 23's vs Nema 17's [it does have a Nema 17 on the Z, but is upgrade-able at checkout], larger cutting area-13" x 21" vs 16" x 16" [also up-gradable to 22" x 30"], and it comes with a real spindle...where with the Shapeoko, you need to purchase the trim router on you own, so if you put the $100 cost for a router into the equation, it makes the upgrade to 22" x 30" even more feasible dollar per dollar.

There is also a few company's making upgrade parts to the OX that adds ballscrews and Hi-Win style linear railes to the basic kit, making it an even more capable CNC https://snbinc.ca/store/index.php?cPath=32&sid=7764984bc000af2cd417b075e9fd006b.

[BadMouth]

12"x18"? Why even bother if it's not at least 48"x96"?

Because ones that big cost a fortune, take up a lot of space, and most of the projects in my head could be done with a desktop sized one.
I'm going to be making pcbs, decorative doo dads, & small parts, not cabs and furniture.

Putting the question of building your own from scratch aside, if you were going to give the Shapeoko kit a serious look, I would suggest looking into the OpenBuilds OX kit first http://www.smw3d.com/ox-diy-cnc-kit/.

There is just a massive online community of people building and upgrading these and when you stack the Shapeoko's $1000 against the OX's $1000, your getting alot more for your money with the OX (Nema 23's vs Nema 17's [it does have a Nema 17 on the Z, but is upgrade-able at checkout], larger cutting area-13" x 21" vs 16" x 16" [also up-gradable to 22" x 30"], and it comes with a real spindle...where with the Shapeoko, you need to purchase the trim router on you own, so if you put the $100 cost for a router into the equation, it makes the upgrade to 22" x 30" even more feasible dollar per dollar.

There is also a few company's making upgrade parts to the OX that adds ballscrews and Hi-Win style linear railes to the basic kit, making it an even more capable CNC https://snbinc.ca/store/index.php?cPath=32&sid=7764984bc000af2cd417b075e9fd006b.

Thank you.  That's very useful info.

[Nephasth]

12"x18"? Why even bother if it's not at least 48"x96"?

Because ones that big cost a fortune, take up a lot of space, and most of the projects in my head could be done with a desktop sized one.
I'm going to be making pcbs, decorative doo dads, & small parts, not cabs and furniture.

Yeah... But they're practically a printing press for money...

[Nephasth]

Check this gadget out!
Shapertools.com

[Howard_Casto]

I saw that on Tested.  It's easily the coolest and most impressive tool I've seen in ages.  Makes way more sense than a large cnc.  Maybe in 5 years or so when the cost comes down.  *sigh*

[Nephasth]

$1500 seems extremely reasonable for its capabilities. But ---fudgesicle--- preordering ---steaming pile of meadow muffin--- anymore...

[Howard_Casto]

I don't think it's bad at all, but unless I'm going into the furniture business or something I can't justify that much for a single tool.  Tight budget and all of that.

[Nephasth]

Break it down in hobby terms... Buy it. Build 3 machines, keep 1, sell 2. Equals a free expensive tool and probably some extra cash in your pocket. From a business stand point though, $1500 is peanuts.

[Howard_Casto]

Maybe when my health improves.  I'm honestly not sure how well cabs would sell in this area....  the coal industry tanking is kind of hurting the community.  If I wanted to build one right and make any kind of a profit I would be looking at $1500+.  Wood is crazy expensive now for some reason.... not a big fan of mdf as anything I build needs to last forever. 

[Slippyblade]

I don't get that thing.  It's a router with a viewfinder.  You'd still need to have absolutely perfect eye and rock steady hands.  Seems ridiculously overpriced to me.

[Howard_Casto]

No it's nearly magical.  The two handles of the router can move and tilt independently and coupled with the natural torque of the bit it adjusts to more closely follow the line as you are cutting.  It can also turn itself off if you try to move too far away.  They say accuracy is improved to a few mms.