Mike's CNC Router Adventure

[mikes]

I have been wanting to start this build log for some time. I have gotten good info from members of the forum, so I hope my contribution will be helpful to others. Below is my CNC router project log. I'll try updating it as it progresses. This is my first foray into the world of CNC. I entered from my experience with building a 3D printer. I guess you could say I caught the builder bug. This is totally a design of my own. I have tried to do the needed analysis for the goals of the machine, but ME I am not. I am machining all the custom parts. I will try to provide drawings for the parts I designed.

Of course, I selected the Acorn for the heart of the control system. This was something I probably over analysed. After looking at the alternatives, it was clear that the CNC12 software was above and beyond the competition. I very much wanted an Open Hardware/Software solution, but I also wanted something that was going to work, and provide the potential for professional results.

For now, I will not get into budget. I learned the hard way that building a CNC cannot be done on the cheap. What I mean by this is that things need to be sized correctly if you are going to meet your goals. Of course, I had a steady stream of packages from China, but even so, I have blown the budget. May be I will circle back to this later in the log.

Thus far, It has been a very enjoyable adventure, and thoroughly believe the journey is half the fun. I will try to document what I have done with lots of pictures. Please feel free to offer thoughts, advice or suggestions. They are all welcome.

Goals:
I am an ameture woodworker, and want to use the router for building lots of things with wood, but I also want the ability to machine aluminum, so the design goals are with these two mediums in mind. I want something close to 4ft x 4ft, and at least 6in of Z-axis.

To give you an idea of the direction I headed, I'll jump ahead for the first picture and show a later snap of the unit. I'll go back in future posts and start from the beginning with parts selection and the build process. Its very much a build in progress, so I hope you stay tuned...



You can see aluminum is the primary material for the design, with the exception of the table, which I will describe in my next post.

[cnckeith]

wow, super nice, thanks for posting looking forward to more photos of the project!

[martyscncgarage]

Mike, looks good. You give good advice about costs.
Look forward to your build.
Marty

[mikes]

Starting from the beginning, I'll go back now and give some detail to the design I came up with. There is nothing particularly special about it. I borrowed elements from here and there, and came up with the rest. It uses a basic gantry design, supported by two linear rails. Before I jump to far into the design, how about a snap?



This is the CNC table support. It's still in the "paint booth". It was built from 1 1/4in square stock, and was my first welding project. I picked up a Lincoln Electric MIG welder at Home Depot. It was on the discount rack. I wasn't in the market for a welder, but it had always been on my list of cool things to have one day. Well, it somehow jumped into my cart, and so began my new adventure learning to weld. The first thing I learned, was that the welder is just the beginning of what is needed to competently weld steel. After a trip to a "real" welding supply house, and more $$, I was on my way to becoming a MIG welder. Thank you YouTube, Lincoln Electric, and all the other online "learn to weld" resources on the web. After about two days of playing around and making practice welds, I felt confident enough to start on the table. The vertical bar stock in the middle will be used to mount the control cabinet and VFD. You can't see from the picture, but I welded nuts to 1 1/4in square plates, and then welded the plates to the bottom of the feet. They well be used to attach wheels.

Ok, back to the design. I'll start with the linear modules I created for the left and right X-axis. These are what the gantry rides on. The structural element is a 30-6060mm extruded aluminum profile. Oh, I should just mention up front that this design in in metric units. It's just easier, and most of the stuff from China is also sized in metric units. Such a mistake our government made not adopting the same standard as the rest of the world. Well I guess its good for the tool makers of the world. Us Americans get to spend money on both. Enough of that rant. Regarding the 30-6060, if you have ever worked with 202Omm aluminum profiles, you will recognize this stuff, it's just bigger. The nice part about the 30, which is the spacing (mm) between the attachment rails, is that the mounting holes for the selected linear rails(SRB20 x 1200mm), match the 30mm. Below is a drawing of the right side profile.

You can see the 1605 ball screw sits to the side of the 6060 and the linear rail on top. At the other end of the ballscrew is a right angle bracket that holds the FF12 ball screw mount (the floating side of the ball screw). Below is a picture of the right linear modules.



Shout out to the aluminum profile manufacturer, 8020 Inc. They are great to work with for the makers of the world. It's not inexpensive, but you get what you pay for in quality and service. Below are some close up pictures from various angles. Next post, I will describe the gantry design and provide some more snaps. Thanks for reading...

[cnckeith]

sweet! nice work.. keep it coming.

[Rosmadi]

Nice

[mikes]

In today's instalment, I'll try to present the gantry design. As a cnc router, the gantry is a key element of the design. It must support the motor, Z-axis linear module, and be rigid enough to prevent flexing given the goals of the design. As I stated in an earlier post, I selected 30-6060mm aluminum extrusions for the structural component for the X-axis linear modules . I did the same for the gantry (Y-axis). I also selected SBR20 linear rails and a 1605 ball screw (Y-axis motion). I originally was going to go lighter and use 20-4040 aluminum and SBR16 linear rails, but after calculating the deflection limits of the 20-4040, I went with the larger extrusion.

The 8020 Inc website has a very nice set of tools, one of which is a deflation calculator. The SBR20 linear rail will add additional stiffness to better handle the X-axis horizontal forces. Now that I have it all fabricated, I love the rigidity I was able to achieve. I think the steppers will stall long before dieflection will be an issue. That covers horizontal forces, what about vertical. Most of that should be static, with the weight of the gantry and motor providing the force needed for plunging into material, but that weight still needs to be supported. To add some additional load bearing and rigidity, I included some aluminum cross members between the upper and lower 30-6060 supports. This is where a picture is worth a thousand words, so let's jump to some snaps. The first is a cross sectional drawing of the gantry supports. These were fabricated out of 1/4 and 1/2in.aluminum. The drawing also shows (to the right) a top view of a support as it would sit on the linear rails of the X-axis.



Now for some pictures of the gantry in various stages of fabrication.

[mikes]

Some more pictures of the gantry, with the first one showing the cross members on the back:

[martyscncgarage]

Looks nice Mike.
Did you do all the cuts of the extrusion yourself? If so, rough cut and mill ends to ensure squareness?
I see you are using closed loop hybrid axis motors. Which ones are you using?
You went with round linear rails instead of profile linear rails and trucks. Why did you choose that? Cost?
I see you are using an 80mm motor. Water cooled? I'm not a huge fan of having to deal with water so am curious.

Machine looks well thought out and engineered. I'm looking forward to the results of your efforts.
I would like to eventually build a 2'x4' machine. 12" of Z. (I already have the slide assembly) I would really like to have the ability to do both routing and plasma cutting by sliding a water table on the machine. They say such combiniations are mediocre at best but I can't justify both and don't have the room for both.

How much do you think you will have in the machine when you are done (or so far?)

Good stuff, thank you for posting.
Marty

[mikes]

Marty, you ask good Qs. I'll try to answer them as I add to this log. I'll start with the stepper motors and drivers I selected.

I went with a set of three LiCHURN LCDA357H drivers and matching three phase NEMA23, LC57H380 1.2 degree 2N.m stepper motors. I have no prior experience with these, but I have read a positive review. They look reasonably well made. I purchased them on Aliexpress. I was interested to see what chip is being used to drive the motors, but that would have required a level of disassembly, I wasn't comfortable with. It looks to be using a variant of a TI TMS320 DSP. Below is a snap of the driver with the cover off.