New Machine Build- 1st CNC - an upsized "book" build

[TLARengineering]

I have recently started work on creating a modified "Book" CNC Router. The book, for those who don't know, refers to "

Build Your Own CNC Machine

Build Your Own CNC Machine

" by Patrick Hood-Daniel and James Floyd Kelly. You'll find their main site http://buildyourcnc.com/default.aspx.

My initial reasoning to modify the existing, proven design is to increase the work area from the current ~20"x~40" to at least a 24"x48". Do I have a specific project in mind with these dimensions? No, not yet. But I'd hate to go through all this effort and not be able to work a quarter sheet of MDF as is.

I am also concerned with the numerous mentions of the work surface sagging slightly in the X-axis. I had a few ideas, but believe I have settled on a torsion box table. I will have overhangs of 1.5" at the top and bottom of the Y-axis which leads me to the third table modification. Dual rails.

I will be placing a dual rail x-axis system onto the table. Here is my current design with the table top hidden.



My thoughts behind the dual rails are twofold. One, I will decrease the load being carried by the Y/Z axis gantry bearings by spreading it out over the two rails. This may also have a side benefit of decreased rail wear as some others have reported. Two, this could lead to increased lateral stability of the gantry. The major downfall of this design is the extreme need for accuracy and "parallel-ness". Also it will bump up the cost by ~$50. Then again, this brings me to one of my Core Values:

"Anything worth engineering, is worth overengineering."
-Chris S.

Okay, perhaps it's not a Core Value...but it is how I tend to do things. (Much to the dismay of my wife)

The Gantry is taking shape. Besides making it taller (Z-axis) and deeper (Y-axis), the Gantry will be made pretty much per the book. I am still considering some sort of reinforcement for the Gantry sides. Either I’ll double up the thickness or I’ll add an angle bolted onto the face. I have read some reports of instability/flexing in the Y-axis caused by movement of the router in the Y direction.



Here is the Y-Axis gantry being squared up (using 1/4" threaded rod for support) so I can measure the other gantry pieces:



I'll also being creating a "Blacktoe" kind of router mount and vacuum attachment. The router mount I'll hand make now and do the vacuum bit once I get the CNC operational.

Here is the stock Z-Axis assembly on the left and the upgraded design (incomplete as of the moment) on the right:



All for now. I hope I haven't gone down a road that just won't work, but I think I'll be okay.

Thoughts anybody?

Thanks,

-Chris

[GreyingJay]

Cool! I've just gotten into all this (e.g. I haven't built anything yet) but I started off by buying that book too. Having read up on the pros and cons of this design, I've opted to try a Solsylva 25"x25" as my first machine. I've even potentially got a great head start thanks to the generosity of a forum member who's offered to sell me some of his old parts.

I like the look of your bed and torsion box much more than the stock book design. I was especially nervous about how the end legs were bolted in only by the edges of the MDF -- edges are MDF's weakest point, no? Maybe I'm wrong but that design just didn't sit well with me. Yours seems to allow more space around the bolts which would make me think it would distribute the weight better.

Wishing you best of luck and hope to see more updates as you go! I will soon start posting my own adventures -- I hope!

[TLARengineering]

[QUOTE=GreyingJay;890112]I like the look of your bed and torsion box much more than the stock book design. I was especially nervous about how the end legs were bolted in only by the edges of the MDF -- QUOTE]

I was concerned about the legs too. I had a design that changed things a bit but decided to try the original way first. I was pleasently suprised at how stable it actaully was! And yes, the edges of the MDF are the most unstable, but since I'm not screwing directly into the edge, no worries. The cross dowels appear to create a really strong, stiff joint.

Good luck on your project too!

-Chris

[jcoats]

Looking forward to some updates. ... I am starting a book build ... need to get back to it.

I have some 'cheap' MDF furniture, and with the right connectors, it is surprisingly stable and durable.

Any mods from the book would be neat. Take 'lots of pictures'.

[rb765]

Ditto. I just bought the materials and will be making my first cuts in the morning. I still have not decided on what electronics to buy, but may just get Patrick's electronics package.

[Grunblau]

Good luck on your build! Your build dimensions/theory are very similar to my design. Check out my post history to see what I did or check out Grünblau Design Studio. I used the keling driver and motors and haven't had any issues. My next small build is going to try out the G-540. Also, if you seal the MDF with polyurethane your machine will get suprisingly rigid/durable.

Cheers!

[rb765]

Beautiful work. Thanks for sharing that site. I am often dumbstruck when I see some of the work that people on this site are producing. I would feel blessed to have one tenth of your talents. Thanks again for the words of encouragement.

[MachiningBob]

Originally Posted by TLARengineering My thoughts behind the dual rails are twofold. One, I will decrease the load being carried by the Y/Z axis gantry bearings by spreading it out over the two rails. This may also have a side benefit of decreased rail wear as some others have reported. Two, this could lead to increased lateral stability of the gantry. The major downfall of this design is the extreme need for accuracy and "parallel-ness". Also it will bump up the cost by ~$50. Then again, this brings me to one of my Core Values: "Anything worth engineering, is worth overengineering." -Chris S.

Very cool build, Chris! I too have just recently started and recently finished the book build. I did a straight book build myself and I've been making cuts and very thrilled that it works.

However, regarding the above comment. I too have noticed the need for "parallelness" however...doesn't the quad rail system require more "parallelness"? Not just lateral, but also vertical "parallelness" with each side's 2nd rail? I mean I can see the torsion box will give you your straightness so that may not be as big a problem as I'm thinking it will be, but I'm interested to hear how this worked out for you.

Also, the ability of the y-gantry to twist...is a bit annoying. Increasing the boxiness of it seems like it will help. I see you have made allowances for two screw holes for the y-axis rail support.

For the book build there is very strong jointing with the y-gantry bottom piece giving maximum surface area against the y-gantry sides to resist twisting, but the only surface area on the top of the y gantry sides is the y-axis rail support with a thin edge directly in the center.

I'm about to embark on upgrading the Y gantry sides, increasing the boxiness, and creating a way to make the BRAs adjustable against the x-axis rail, while also giving me more Y axis cutting area and if I can swing it a more gantry centered X axis cutting area.

If I can get to the point where I'm not tightening things all the time...I'll be happy. I'm also using birch plywood for the new pieces.

[dogtoes]

.

[TLARengineering]

As an update: The Machine lives!!! I applied power for the first time today. I will post pictures, and hopefully, a video link tomorrow. Still having major issues with limit switches not being recognized...but I'll start a whole new thread for that.

For the most part it looks just like my original design...had to change the Z-axis a bit. Anyways...pics "soon"!

-Chris

[TLARengineering]

Hooray! As promised, here are pictures and some YouTube links of my new rig in action.

Pics
CNC pictures by dogtoes93 - Photobucket

and here a video:

TLARengineering's Channel - YouTube

Now the easy part is over...now I gotta learn how to use it! LOL

Thanks,

-Chris

[TLARengineering]

So I have my limit switches working properly now thanks to these great forums...but now I'm having possible G Code issues?

I'm using Mach3 to control my machine by the way...

If I type code by hand (at the MDI screen), I can make a perfect 1.00" square (as seen in the upper right of this image)




But, in Aspire, I created three 2.00 inch squares (one outside, one inside, and one pocket) and then a couple of holes to drill/pocket. Using a .25" end mill in my router, I get the results as seen in the image. Note: visible are two attempts at running this...but left and right sides, as seen in the image, are the same.

here is my code...darn if I can tell what my deal is. I really hoping that those of you, who have been here before, can point me in the right direction.

Thanks in advance,

-Chris