Looking to build my own CNC router

[thebuggman]

Hi everyone,

It's been many years since I last used a CNC, but I would now like to build my own.

There's so much info here, that it will take me a while to sort through it all and I'm sure I'll have a ton of questions along the way.

Basically I want a typical 3 axis cnc, software to run the cnc as well as to create the designs & files needed, stepper motor controllers...

Not sure if I want to use the chain drive systems I've seen or go with screw drive & I'm just getting ideas for the bearing system & how I'd like to build everything.

I have a small shop (garage), but I'd like to build a good sized cnc to accommodate larger projects without the need to re-set or re-clamp the parts. I'm quite a good woodworker, so building everything from plywood, mdf, etc shouldn't be much trouble.

I'm thinking about making interchangeable router mounts so I can change routers if needed or switch to smaller or larger routers as needed.

Precision will be a big part of the parts I'll be making & I'd like to be able to use tiny bits all the way down to 1/16" if possible.


Any tips, suggestions or helpful info would be appreciated.

[CNC Lurker]

A few questions to consider, and budget is number one because it will affect and may limit everything else.

1. What is your budget?
2. What cutting area do you need? Remember, you may be locked on your Y-axis, but you can index your X-axis. In other words, on a 2ft x 3ft cutting area, you may be limited to 2ft wide, but you can cut a part 4ft long by using dowel pins or some other method to index it (cut then shift part over).
3. What will the machine be made of? MDF, plywood, structural c-channel, 80/20 extruded aluminum, etc.
4. What tools do you have access to? A welder, drill press, jig saw, table saw, etc.
4. ACME threaded rods work great, but once you get to 4ft or longer, you might want to consider something else, such as rack-and-pinion.

After you have the main frame and moving parts figured out, don't forget:
1. Steppers
2. Power Supply
3. Cables
4. Computer
5. Mach 3 or equivalent
6. Cut 2D or equivalent (convert to g-code)

Actually the site in the link has some great info, and here is a link to a budget file that can be opened in Excel:

CNC Router Budget LINK

[thebuggman]

Thanks for the info.

Budget will be the major factor, as with most people. If I can build a little now & expand to the other areas when funds are available.

I am well stocked with woodworking tools, table saw, jointer, planer, band saw, drill press, routers, etc. so I'm leaning towards a mdf or plywood design, but I'm also looking into 80/20 aluminum to see if it will save some work... although I'm sure it will be more expensive.
No access to a welder, so that will leave me bolting the parts together, but that may help make the design more flexible.

I have a couple extra PC's laying around that should have enough processing power to run the software necessary, but none have a parallel port... I've been using a USB to Parallel adapter for an old laser printer that works perfectly, so I may look into getting another one of those adapters if it will interface with the controllers.

I'd like to be able to scan in a design & convert into a usable cut program, but I'm not familiar with the different software programs required.

The stepper motors & controllers are something I don't have a lot of hands on experience with, but I'm starting to familiarize myself with the terminology.

[ger21]

How big of a machine are you looking for?

The Joe's 2006 machine is a solid wood machine. If you want something bigger you'll need to deign it yourself. Here's someone building a wooden based machine from LVL's.
http://www.cnczone.com/forums/diy-cn...teel_base.html

I've been using a USB to Parallel adapter for an old laser printer that works perfectly, so I may look into getting another one of those adapters if it will interface with the controllers

USB to parallel adapters won't work for CNC. But, you can always add a PCI parallel port card for $20-$30.

I'd stay far away from chain drive. Any time I've seen it attempted on a solid machine, it's the weakest link and is usually the first thing replaced. As was mentioned, Acme works very well for up to about 4 ft. Anything longer, and I'd recommend rack and pinion.

I'm thinking about making interchangeable router mounts so I can change routers if needed or switch to smaller or larger routers as needed.

Just start with the largest router you'll need. It should be able to handle all your needs. Don't bother with the added complexity of swappable mounts.

[thebuggman]

Ok, I've got a parallel port card coming so that's one small piece of the puzzle taken care of.

I'm thinking about making the usable table space about 3' wide by 4' long. That should be large enough for almost anything I'll need & if I need anything longer, I should be able to index the material on the table once I get familiar with the software... looks like Mach3 is very popular.

I've got some of my 1" black pipe for the rails & I'm looking to do something similar to Joe's 2006 & the jgro designs... with a few of my own ideas thrown in.

I'm going to start off with the 1/2" x 13 threaded rod, this way it won't be a huge deal to change it to some 1/2" acme threaded rod later on (when I make a few bucks from the cnc). I found some coupling nuts that I'm going to use for the carriage nuts. There's very little slack with them, unlike the shorter 1/2 x 13 nuts so I'm hoping I don't need any anti-backlash nut.

Not sure on the main material at this point, either 3/4" MDF or plywood or maybe a combination of both.

The table will probably be 2 layers glued & screwed of whichever material I pick with an additional layer of hardboard on top in case I happen to cut into the table top, I can easily change the hardboard to eliminate any gouges.
I'm still looking for ideas on clamping, maybe some T slots in the top, maybe bolt holes for hold downs.

For the gantry legs, I'm thinking about using 2 pieces of 3/4" material (glued & screwed together) to add more mass & lessen the chance of warping or flexing under heavy loads.

For motors, controllers & power supply... I have no idea right now & would appreciate any input or suggestions.

I've seen a few posts describing 200oz-in motors & some with 400oz-in motors. I want plenty of power to move what will likely be a heavy gantry/y/x axis as well as enough power to move a 1/2" straight bit through oak without taking 1/16" deep cuts.

As with most tools, I'm sure more power is better but I want to ensure I have the proper power supply & controllers for the proper size motors.
This is a step I don't want to skimp on, but I don't want to go way overboard if a moderate motor/power/controller package will be sufficient.

What are some reliable sources for parts, or even a package?

For routers, I've got a Freud 3 1/4hp plunge that I use in one of my router tables for raised panels. I have a Bosch 2 1/4hp that I use for hand held work due to the super soft start & variable speed. I've got a single speed PC690 1 1/2hp that I use in a smaller router table for most common jobs. I have a few dremel/rotary tools for small or detailed work.
I'm thinking about making interchangeable motor mounts so I can switch from a dremel (1/8" bits) to a router when I need to do more heavy duty work.

Thanks for the info so far & keep it coming

[ger21]

A Gecko G540 package with 380oz motors is the most powerful package for the money, and you won't need to upgrade letter when changing leadscrews.
If you can find the money, going with 2 or 5 start acme from the start will save you a lot of time later. It'll also give you at least 5 times more speed.

You can get 1/8" coillets for a Porter Cable from Precision solid carbide tools for woodworking and metal forming.

[louieatienza]

Ok, I've got a parallel port card coming so that's one small piece of the puzzle taken care of.

I'm thinking about making the usable table space about 3' wide by 4' long. That should be large enough for almost anything I'll need & if I need anything longer, I should be able to index the material on the table once I get familiar with the software... looks like Mach3 is very popular.

I've got some of my 1" black pipe for the rails & I'm looking to do something similar to Joe's 2006 & the jgro designs... with a few of my own ideas thrown in.

I'm going to start off with the 1/2" x 13 threaded rod, this way it won't be a huge deal to change it to some 1/2" acme threaded rod later on (when I make a few bucks from the cnc). I found some coupling nuts that I'm going to use for the carriage nuts. There's very little slack with them, unlike the shorter 1/2 x 13 nuts so I'm hoping I don't need any anti-backlash nut.

Not sure on the main material at this point, either 3/4" MDF or plywood or maybe a combination of both.

The table will probably be 2 layers glued & screwed of whichever material I pick with an additional layer of hardboard on top in case I happen to cut into the table top, I can easily change the hardboard to eliminate any gouges.
I'm still looking for ideas on clamping, maybe some T slots in the top, maybe bolt holes for hold downs.

For the gantry legs, I'm thinking about using 2 pieces of 3/4" material (glued & screwed together) to add more mass & lessen the chance of warping or flexing under heavy loads.

For motors, controllers & power supply... I have no idea right now & would appreciate any input or suggestions.

I've seen a few posts describing 200oz-in motors & some with 400oz-in motors. I want plenty of power to move what will likely be a heavy gantry/y/x axis as well as enough power to move a 1/2" straight bit through oak without taking 1/16" deep cuts.

As with most tools, I'm sure more power is better but I want to ensure I have the proper power supply & controllers for the proper size motors.
This is a step I don't want to skimp on, but I don't want to go way overboard if a moderate motor/power/controller package will be sufficient.

What are some reliable sources for parts, or even a package?

For routers, I've got a Freud 3 1/4hp plunge that I use in one of my router tables for raised panels. I have a Bosch 2 1/4hp that I use for hand held work due to the super soft start & variable speed. I've got a single speed PC690 1 1/2hp that I use in a smaller router table for most common jobs. I have a few dremel/rotary tools for small or detailed work.
I'm thinking about making interchangeable motor mounts so I can switch from a dremel (1/8" bits) to a router when I need to do more heavy duty work.

Thanks for the info so far & keep it coming

Likw Gerry mentioned you can get precision collets and bits from PreciseBits.com, and I believe they have them for the Bosch and PC routers. You definitely want variable speed for different materials/bits. If you use a plunge router as a spindle there are other considerations to consider concerning mounting. My smallest bit is .024" which I use for fretboard slotting.

The usual wisdom for steppers is that smaller motors work better with finer pitch screws and larger motors with coarser pitch screws. Rack and pinions setups can involve gear reduction. Also as Gerry mentioned, I'd go with multi-start leadscrews at least, so that you get good rapids speed. To me it's very hard to quantify how much "accuracy" one really practically can use especially when cutting wood, whose dimensions can grow an order of magnitude more than the resolution of the machine. I feel it's more important to remove as much backlash as possible; repeatability is key to successful machining. If you're on a leadscrew budget, Enco sells 1/2" Acme screw inexpensively, and with DumpsterCNC anti-backlash nuts that have built-in flanges, you'll get better performance and life expectancy. You'd have to spin that threaded rod pretty fast to get any kind of speed (and for cutting most woods, you need speed to keep the wood from burning), and steel-on-steel is going to wear fast without constant lubing. You might be able to get a block of Delrin or UHMW and make your own nuts however...

[thebuggman]

I've done a little searching for the 1/2x10 acme rods & I came across this LINK, but it doesn't indicate how many starts it is.
From the looks of the stock image, it appears to be a single start.

From ENCO, I found the 1/2x10 5 start thread HERE, but it's almost double the cost of McMaster Carr's #99030A704.

Speed isn't as important as accuracy to me. I know I need a certain feed rate to keep the bits from burning wood just like when using a hand held router or router table, but I believe I should be ok initially if I use 1/8" deep cuts in wood.... it will be super slow, but at least it will save my back bending over a router table for hours or using a hand held & straightedge.
I know after a while, I'll want to speed the process up, but right now it will break the budget to invest $200+ in lead screws, not to mention the collars, etc.
Since I decided to use 1/2" threaded rod now, at least I'll be able to re-use the bearings when I can afford some 5 start acme 1/2" rods.

I've got some small projects in mind that will require 1/16" or 1/8" bits and the tolerances will be within 1/32" or less. These will be 1/8" or less depth in 1/4" thick lexan.

I wasn't aware of the small vs large stepper motor theory either. Since I'll likely be using the 1/2x13 regular rod now & the 1/2x10 5start acme later on, it sounds like I'd be better off using the larger motor in the beginning so I'll have the extra torque needed later on.

My thoughts on the regular rods was to have them as enclosed as possible to prevent as much buildup of debris as possible & keep a nice coat of grease on them on a regular basis.

My design should have the x axis rod located under the table in the center, while the y axis either inside a boxed gantry or behind the gantry if I use a single 3/4" board to connect the top area. The z axis should be pretty well enclosed due to the limited space available.

For the table, I'm thinking of a 3/4" plywood sub base/torsion box with a 3/4" mdf top layer and possibly a sacrificial 1/4" top layer. I'll need the entire cnc to be portable in my small shop, so I'm looking to add legs & heavy duty locking casters. It would be nice to enclose the area under the table for storage of bits, etc. as well as have a safe location for the PC & electronics.

I'm trying to decide on a hold down method still... maybe T slots in the mdf, maybe several rows of screw holes with T nuts attached from underneath where I could drop a bolt through a clamp & tighten down wherever I need.

Appreciate all the helpful info guys!

[ger21]

Rather than 1/2-13, you should at least go with 1/2-10 single start acme. It'll probably give you 50% more speed than 1/2-13.
$14 for 6 ft at McMaster Carr, part # 98935A033

I've got some small projects in mind that will require 1/16" or 1/8" bits and the tolerances will be within 1/32" or less

As long as it's rigid, and square, even the most poorly built machine should be repeatable to about .005" or better

Accuracy should not be a problem at all.

[jeffreymatthias]

I've put a team together to create a plan for a complete CNC machine that is scaleable (all sizes use the same y and z axes) from 2'x4' to 4'x8' (6" depth). It uses rack and pinion drives and is fairly affordable. We've got a Kickstarter project going to raise the capital to finish all the details like limit switch placement, cable management and build documentation. One of our reasons for this was because we, too, had to drudge through all the info out on this site and there are so many ways to do it that it got overwhelming.

Check out our project at FurnLab - Home.

If the project isn't for you or you're in a hurry to put your machine together, we'd sure appreciate it if you could pass it along to someone who might be interested.

Cheers,

Jeffrey Matthias