Stepcraft 2: a milling, carving, cutting, engraving and 3d printing machine

I was surprised that I had not seen it here. I think it is a wonderful machine to have.

Quote from the Kickstarter page:
Stepcraft 2 is the world's first universal desktop CNC solution designed to turn your ideas into reality.  It is the only machine that can Mill, Carve, Engrave, 3D Print, Laser Engrave, work as a Vinyl/Craft Cutter, Plot and more...  Stepcraft 2 will be the ONLY desktop CNC system with an ATC (Automatic Tool Changer), making complex jobs even easier.
The Stepcraft is available in 3 sizes and plenty of pledges to choose from. The project has reached it's target on Kickstarter already (by 3 times). More at the Kickstarter project page: https://www.kickstarter.com/projects/224743317/stepcraft-2-universa...

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Comment by Gary McCray on April 10, 2015 at 12:11pm

Hi Rob,

I notice that BusyBee - Craftex is pretty much the same as Grizzly in the US (seems like the tools may even be made in the same plant).

I am a big fan of Grizzly, its always a bit rough, but a great value for the money.

Half my tools are Grizzly.

Best,

Gary


Developer
Comment by John Arne Birkeland on April 10, 2015 at 1:07pm

Rob, if you are skilled in tools and have a shop, then building a nice CNC is in many ways easier then designing and building an octo from scratch.

The keywords on ebay are "linear rails" and "backlash ballscrew" and "cnc spindle". Together with Nema stepper motors these things you get cheap from china. Then invest in a Gecko drive motor controller and run LinuxCNC on a computer, or go open hardware with the Smoothieboard controller and you are set.

The biggest advantage of DIY is that you can go for a large work size without having to mortgage your house. A common approach is to use a thick MDF plate as the base mount for your build. I am planning a rebuild of my 600x400mm CNC into a 1500x800 one, and should cost me less then $1000 in parts with new linear sliders and ballscrews.

Comment by Gary McCray on April 10, 2015 at 8:44pm

I have looked at the step craft Kickstarter offering and decided I ought to say something about the featured machine.

They claim that this is a rigid enough machine to mill aluminum

But there are two very significant items that severely compromise their machine in my estimation. 

They do not use linear ball bushings running on steel rails.

Iinstead they use opposed grooved ball bearings with steel exteriors running directly on a matched section of their aluminum extrusion.

That is how my radial arm saw works and it is OK for low side or angular force applications, but if side or angular force is applied, it depends on the tolerance of the bearings and the clearance (or lack thereof ) of the bearing shells and the aluminum extrusion for its clearance / tolerance and steel riding against aluminum is not a good wear material either (even my radial arm saw has steel rails).

The other thing is that they are using a plastic antibacklash screw instead of a ball screw, geve me a break, those have a limited life and have increasing backlash or clearance according to force applied.

In my opinion if you want a machine you can really use you need genuine ball bushings on steel rail and you need genuine ball screws.

They aren't cheap, but they are the foundation of these machines.

This is the style of linear bearing and rail I use and prefer because they are relatively inexpensive and very rigid and rugged:

My CNC macine originally had an MDF base, but I found a great place to inexpensively get the extrusions for a nice TSlot aluminum table and if anybody wants to know, just contact me through my CNC  Is Fun website and I will give you the information.

http://cncisfun.com/index.html

Basically, I do not think the featured CNC machine is a good investment even though it seems reasonably priced, the compromises are too severe.

Also Rob,

Skip getting the 3D printer and just get (or make) a good gantry mill with sufficient vertical clearance to permit you to achieve the height you want from a 3D printer nozzle.

The mill will work fine as a very large bed 3D printer simply by swapping out the spindle holding plate.

And you will also have a competent mill.

Cutting to any depth is really not a problem, on CNC you just keep repeating the cut incrementing the depth till you are done.

There are very nice high frequency air or water cooled synchronous spindle motors with rpm setting and maintaining controllers available from China (check Ebay).

You can even get them with four German or Japanese bearings (the important part).

Best regards,

Gary

Comment by JB on April 11, 2015 at 1:43am

Hi Rob

If you're interested in doing a DIY CNC on the cheap for low to medium duty work, and for larger work areas than Step Craft maybe check out the v-slot site for some designs here: http://openbuildspartstore.com/ and the plans for the OX here: http://www.openbuilds.com/builds/openbuilds-ox-cnc-machine.341/

I completely concur with the advice not to mix 3D printing with cnc machining. You're better off having a dedicated 3D printer, as print speeds with CNC based ones are typically so slow it becomes uninteresting to wait long for a big print anyway. Besides big prints are never as good, structurally sound or as fast as milling timber or aluminium. Also reprinting a big print because of a error in design or print is a long tedious process, so keeping 3D printed parts for complex small volume components is advisable overall. Breaking up the 3D components into smaller parts is also beneficial for doing repairs etc or incremental design changes. Also don't under estimate design times...a Grabcad type site for UAV/multi/heli type CAD files would be nice to have to cut down on design work and time, but sadly we haven't got one of those yet.

BTW I can highly recommend a Felix 3D printer for size, speed and upgradability price/performance for PLA printing. ABS printing is also possible but PLA is easier IMHO, especially when starting off.  

Regards

JB 

Comment by Rainer K. on April 11, 2015 at 1:52am

@ Rob

the machine is great.
a year without any problems.
production of the machine in iserlohn germany.
  very nice helpful people.
control over Estelcam.de with arduino very good

Comment by Rob_Lefebvre on April 11, 2015 at 8:21am

Hmmm... interesting.

JAB and Gary, you both know I'm perfectly capable of figuring out how to make a CNC machine.  My problem is just time.  I really don't have time to figure it out.  I need tools, not another hobby.  ;)  I'd be capable of assembling a kit.  And *maybe* following thorough DIY instructions with easy to source parts, and using a well figured-out electronic/software system.  But if there's any finagling involved, I just don't have time.

I take Gary's advice on the construction of the Stepcrafter very seriously.  On the other hand, Rainer says it works well.  And it is made in Germany which does carry a lot of weight for me.  Hmmm....  Gary, worst case scenario, if it's as bad as you suggest, you still think it would not be suitable for cutting out frame plates?  That's really what I want.  I tend to try to use as many OTS CNC cut helicopter parts as possible, as you simply cannot match the value of professionally designed and manufactured CNC parts.

For example, I really like these things, and at $36, there's now way I'd try to make something similar at home if I can just buy these.

http://www.helioption.com/store/index.php?main_page=product_info&am...

I'm pretty pragmatic about that stuff.

What I do need to make is custom frames.  I have thought about just doing it the slow way.  I can cut the hole pattern with the DRO on my mill, and then mark corner for cutout with holes, then just cut out the frame manually udiydrones.comkers.  But that's slow.  I'd really like to just design something, and have it cut.

For aluminum, I can have them cut cheaply locally at a waterjet place.  But not CF.  And I'm not super impressed with the finish on waterjet aluminum.

And yes Gary, my machine is the same as the Grizzly.  There's one overarching brand name that gets used for these machines, I forget what it is though.

Comment by Gary McCray on April 11, 2015 at 11:07am

Hi Rob,

I totally understand about not wanting yet another project, it took a long time and a lot of effort to put together my system with a fair number of false starts.

However, there are actually a bunch of systems available off the shelf that are readily usable for what you want to do.

I do agree that being made in Germany does lend some authority to the StepCraft machine, but the facts remain that they are using a plastic lead screw nut and are using a very questionable rail system methodology.

It might be OK for light occasional work, but I suspect it would seriously slow down any sort of extended or light production work to a crawl and it would almost certainly wear quickly.

They usually use acetal or delrin for the screw nuts and they do not like heavy loads or inappropriate lubricants.

And the grooved steel ball bearings running on an Aluminum extrusion (even hard anodized) is really not the ideal solution.

And it relies on pre-load for maintaining tolerance and reducing backlash.

That said, at the price asked it is probably a nice light duty hobby level tool if thats what you want.

Anything you want to actually use to produce significant output will cost at least $3000.00 or more likely $4000.00 as a ready to go thing.

I imagine like me most of what you want it for is contour routing and drilling 

There are several machines somewhat similar to this that can do that just fine for you:

http://www.woodcraft.com/Product/853520/General-15-x-20-i-Carver-CN...

One thing you should ensure is that any machine you get uses real full supported rails with linear ball bushings and that it uses real ball screws.

There are also a number of companies who sell them as ARF kits including all the mechanical parts and stepper motors, with or without stepper drivers, power supply, and G code driver program. Some even supply the computer.

Honestly you should not shy away from even a bare bones one of these kits including just the steppers, there are several perfectly excellent drivers available (Geckos are great), and a power supply is no problem.

There are two primary G code conversion programs the old standby is Mach 3 a DOS based program that works quite well and uses the old fashioned printer port control method through a driver board.

And the one that I am using which is a microcontroller based USB controller board from Planet CNC.

I am very happy with my system in this regard, I was using Mach 3 and converted to this. 

Many whole system manufacturers provide their own conversion program or have entire integrated CAM programs set up to operate them.

I am leery of these because many of them are not G-Code based or don't support a reasonable subset of the G-code library.

Generally you want a good G-Code interpreter / Manual control / virtual code execution program and a completely separate CAD/CAM program that you use to produce your G Code with.

In line with my KISS philosophy, I try to avoid getting locked into single manufacturer solutions.

Hope this helps,

Best,

Gary


Developer
Comment by John Arne Birkeland on April 11, 2015 at 12:58pm

I also want to inject that regardless of the route you go with either a complete kit or a more DIY oriented approach, it will regardless be a steep learning curve making 2d/3d drawings, generating g-code and operating the machine with correct bits, rpm and feed rates. I highly recommend looking at the http://www.vectric.com line of software, to make the process much more intuitive.

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