Newbie - Looking for some guidance

[mctabish]

I have been browsing around for a few days and been taking a lot in.
I am getting ready to built a router table (still need to convince my wifie I have the "need")
I have a craftsman router for the mid 90s.

Purpose would mainly be wood and foam shaping, but would like to occasionally mill aluminum.

Eventual goals would be to handle full sheets

Immediate use would be to construct new drawers for our kitchen and RV with Baltic Birch. I would hope to use Dovetails (can CNC cut dovetails? I am presuming if I design the drawers that way)

I have had some experiance woodworking, worked (40 plus years ago) in a cabinet shop.
My access to tools is a little limited. I have a chop saw, table saw (small), saws all, sabre saw. Router, a few drills (no drill press). normal hand tools. Oxy-Acetylene torch (no Acetylene tank right now (30 plus years of lack of practice)
I DONT have a planer or joiner table (I do have hand held power plane)
So tool wise, I have enough to get going, but not quite as precise as I would like, so this likes like a case were I will build a CNC to build a better one. Seems this is a faily standard practice.

So far, it seems like I am leaning towards a rack and pinion setup. I have a few ideas I have NOT seen yet in this area. I was wondering how well it would work to drive the spur gear with a worm and worm gear instead of a belt? Also, I was thinking about an axel from the pinion across the x dim., driving a second r&p. This would seem to eliminate torque issues.

I would like to probably start with a 5 axis controller, adding the 4th drive and stepper later on, and even later on the 5th. I can definently envension their use! I dont want to re-buy the more expensive parts.

My first dimensions would probably be 3' x 6' with 12 inch z.

With that being said, I am looking for suggestions.
I would be wondering what steppers size recommendations. again, probably go with slightly larger ones so I dont have to re-buy, but I dont want to drop 600 on a set of three.

What are the thoughts about the R&P ideas I have
I would probably be building the first one outa birch ply.
What is the precision of R&P compared to ACME screws?

It seems that a supported linear bearing would be best. What designs are good, but economicail?

As for computer, I have a laptop w/o printer port. I recently got this one and I dropped a fair penny for it (FULLY loaded - except no printer port Well it DOES have one on the port replicator) so selling the gal of my life on a new one would be hard!

What design software is fairly easy to use (lots of computer experiance, not much in CAD.

From what I am understanding, as for the end results, the CAD software does not care if 3 axis, 4 axis or more. Is this correct?

What are my options for CAM software? Something that is Windows based (32 or 64 bit) and I guess USB. Would I need to move to new software for the 4th or 5th port? I would prefer public domain, or faily cheap.

Should I also go rack and pinion on the Y and or the Z axis?

Have people had good luck finding the metal goods from metal scrap yards?

How does bit changing effect the outcome, is there a way to "re callibrate" for the new bit? Example would be changing from straight bit to dovetail bit.

Is there a way to move the work peice to a different position once cutting has started, so that a 3 foot machine could actually cut 4 ft peices. If so, how would this be done?

Lots of questions...

I just want to start having fun, but need some education first!

Thanks VERY much in advance!

Mc

[ger21]

Lots of questions here.

Immediate use would be to construct new drawers for our kitchen and RV with Baltic Birch. I would hope to use Dovetails (can CNC cut dovetails? I am presuming if I design the drawers that way)

There are special bits for cutting "modified" dovetails. To cut regular routed dovetails, you're machine will need to be able to hold the boards on end.

Personally, I'd cut them on the table saw with a locking rabbet joint. Probably at least 10 times faster, and will outlast you if done properly.
Lock-Rabbet Drawer Joints

So far, it seems like I am leaning towards a rack and pinion setup. I have a few ideas I have NOT seen yet in this area. I was wondering how well it would work to drive the spur gear with a worm and worm gear instead of a belt? Also, I was thinking about an axel from the pinion across the x dim., driving a second r&p. This would seem to eliminate torque issues.

Don't try to reinvent the wheel. Worm gear will give you a lot of backlash, and is not very efficient.
The easiest and most common method is to use two motors, one on each side, and slave them in software.

What is the precision of R&P compared to ACME screws?

Generally, they are very similar. However, you can spend more money to buy higher precision items. But realistically, they'll be far more precise than the rest of the machine.

It seems that a supported linear bearing would be best. What designs are good, but economical?

Look at Dual V wheels and track. OR Look at the Mechmate forum to see how to grind you're own track from steel angle. MechMate CNC Router - Build your own with our detailed plans

As for computer, I have a laptop w/o printer port. I recently got this one and I dropped a fair penny for it (FULLY loaded - except no printer port Well it DOES have one on the port replicator) so selling the gal of my life on a new one would be hard!

What control software do you plan on using? In most cases, you're best bet is to buy a dedicated PC to use. You can get a decent one on Ebay for $100 or less.

What design software is fairly easy to use (lots of computer experiance, not much in CAD.

Extremely difficult question. What's easy for some is impossible for others. And what you want to make has a huge influence on this choice.

Generally, for router users, Vectric's packages are far and away the easiest programs to use. Vectric - CNC Software Solutions - Wood Carving - Engraving - Signmaking - Routing - Machining

For designing, look at either V-Carve Pro or Aspire. If you're doing more mechanical type parts, there may be other options.

From what I am understanding, as for the end results, the CAD software does not care if 3 axis, 4 axis or more. Is this correct?

CAD has nothing to do with cutting. CAD programs create 2D drawings or 3D models. It's the CAM software that creates code for the machine.

What are my options for CAM software? Something that is Windows based (32 or 64 bit) and I guess USB. Would I need to move to new software for the 4th or 5th port? I would prefer public domain, or faily cheap.

CAM doesn't control your machine, it takes CAD files and creates g-code files, which are run by the machine control software.

Vectric's programs are CAM programs. There are free CAM programs available as well.

For Machine control, you have a few options. Most use Mach3, which is $175. A lot use EMC, which runs on Linux, and is free. There are also some DOS programs if you want to go that route.
There are a few other more expensive options as well. FlashCUT, USBCNC, CNCUSB, WinCNC, ...

Should I also go rack and pinion on the Y and or the Z axis?

The answer would have a lot to do with the design of the machine, as well as performance requirements.

How does bit changing effect the outcome, is there a way to "re calibrate" for the new bit? Example would be changing from straight bit to dovetail bit.

You create your code for specific tools. The only thing you need to calibrate is to zero the Z axis. When you change tools, you need to set the Z zero position for the new tool.

Is there a way to move the work peice to a different position once cutting has started, so that a 3 foot machine could actually cut 4 ft peices. If so, how would this be done?

Usually called indexing. Probably the best way is to have the machine drill some locating holes, and use dowels to re align the part.

Honestly, it sounds like you need to do a lot more research before you spend any money. The more you know, the cheaper it'll be in the long run.