Yet Another 8020 CNC Build

[jsantos]

Hi All,

I've been lurking here for almost a month now trying to learn everything I can about building a CNC router. I'm a newbie and know very little about building a CNC. Everything I know about CNCs came from a couple of books, the threads in this form and from Ahren of cncrouterparts.com. Ahren has been very helpful in answering questions I have.

So now I'm ready to start building one. So here goes:

- 8' x 5' built mainly from 8020 aluminum
- Carriages & R&P from Ahren
- Rack from Moore Gear
- Rack clamps from Ahren
- Cold-rolled steel from McMaster
- GeckoDrive G540
- 380 oz-in from Ahren and Keling
- Power supply from Keling
- 8-inch z-axis from K2CNC
- Mach3 software
- Haven't decided on cad/cam yet

I've attached pictures of the plan. I tried to upload a sketchup file (2.3M) but I keep getting upload errors.

1.jpg - The whole thing.

2.jpg - I'm recycling the support and legs from my existing workbench. The CNC will also double as my workbench.

3.jpg - Frame. The overall frame will be 3030. 1515s will be ued to support the table top (mdf).

4.jpg - X-Axis Drive - Will use R&P from Ahren. Driven on both sides.

5.jpg - Gantry - The verticals supports are 1530. All the rest are 3030.

6.jpg - Y-Axis Drive. Will use R&P from Ahren. Not sure if I really need the carriages at the bottom.

7.jpg - The z-axis will be mounted on the stock aluminum shown.

8.jpg - Closer view of the overall CNC.


Now, if only the weather will cooperate and warm up a bit so I can start. :-(

Comments and suggestions are solicited and very welcome!

[ger21]

You'll need to support the sides somehow.
And try zipping the Sketchup file and upload that.

[jsantos]

You'll need to support the sides somehow.

I was afraid of that. Would putting support in the middle of the sides suffice?

And try zipping the Sketchup file and upload that.

I did zip the file. It was a 6.8M file and zipped down to just over 2M. I got the error (failed to upload) when I tried uploading the zip file.

Thanks!

[ahren]

Joe,

Looks like a really stout machine, although I'm not sure you need all of the framework you have constructed. I personally would use a piece of 3060, a 7" wide piece of steel on the front of it, and the R&P running along the top (turned sideways). This should be easier to construct and just as strong if not stronger. Plus, this will only require two extended carriages on the gantry.

Ahren
www.cncrouterparts.com

[jsantos]

Hi Ahren,

Is a 7" cold-rolled steel available? I checked with McMaster and Grainger and it looks like the widest they have is 6". But based on your suggestion, can I turn the rails vertical using 2 4" and 2 3030? Or would not pose a problem with possible unevenness?

[ahren]

Joe,
McMaster and Grainger have crummy selections on raw materials. I would personally order from an actual metal supplier. One suggestion is speedy metals (speedymetals.com). Here's the page with 7" CRS:

http://www.speedymetals.com/c-8213-1018.aspx?pagenum=4

Your other route might work too. Unevenness isn't really a problem. The only thing is you want a 1/2" overhang from the steel past the aluminum to set the spacing for the R&P correctly.

Ahren
www.cncrouterparts.com

[jsantos]

Hi Ahren,

Thanks for the link to speedymetal.

Revised gantry picture is attached. I'll look at using a 7" CRS but will use 2 3030 instead of a 3060 as I have the 3030s but not the 3060s. :-)

Couple of questions on using a vertical rail:

1. The racks will now be on top. Would that cause a problem with wood dust?

2. The two carriages are now held together by just the z-axis mounting plate. Will that be stable enough?

[ahren]

Looking good -- that's what I had in mind. If you are going with two pieces of 3030, however, I would get 8" wide steel and put a space between them. The faces on the extrusion are not exactly flat (they get flat once you fasten things onto them), and you need the 1/2" clearance on either side, and things are pretty tight at that. It would stink for a small twist in the extrusion to keep everything from going together nicely, so it will be nice to have a little adjustability.

As for the R&P on top, the dust shouldn't be a big problem, since the teeth of the rack are still oriented sideways.

For the Z axis, it will be stiff enough if:

1) You use a thicker plate

OR

2) You make it out of steel

Or both. This is going to be one nice beefy machine!

Ahren
www.cncrouterparts.com

[jsantos]

Hear you on using an 8" rail. Didn't think of the possible problems with 2 3030s.

So how thick a steel plate should I use for the z-axis? If I want to go aluminum, how thick should it be?

BTW, the motor, R&P and rack clamps arrived today priority mail. I didn't know priority mail delivered saturday. :-)

And I love that the motor already has the DB-9 with the current resistor set installed. Thanks!

[Senna]

The redesign of your gantry looks nice. It also eliminates a number of those expensive corner brackets... not to mention the hardware to attach them! Certainly a stiffness increase over what your first design had.

It's inspiring to see these new R&P designs unfold. The previous limitations of table size have been virtually eliminated without the attendant logarithmic increase in price one would see with other linear rail/ballscrew designs.

Looking good!

Senna

[jsantos]

Thanks Senna.

The R&P solution does look much lower, cost-wise, than other solutions. Hopefully, it will work just as well. :-)

I've taken apart my workbench and started building the CNC frame on top of it.

Unfortunately, it will be below 0 in the next couple of days, so no working in the garage for me. :=(

[jsantos]

The weather is warm enough now for me to work on the garage. Okay, it's still only 18F, but with an infrared heater and dressing up looking like a Michelin man, I can keep warm enough. :-)

The pictures show what I've done so far.

Ahren - How big are the holes that I should be drilling on the CRS rails? I was thinking of making them 3/8" instead of 5/16" to allow for adjustments I have to make them parallel to each other. Is 3/8" too big or too small?


Old workbench.jpg - This is what my workbench looked like before.

CNC Frame 1.jpg - I disassembled the workbench and lengthened its rails to 6 feet. The basic frame of the CNC is now put together. The 8020 sitting on top is not part of the frame. I was using that to make the rails of the frame parallel.

CNC Frame 2.jpg - The frame raised so I can tightened the bolts underneath.