my first CNC Router - log

[E.C]

Hi all,
I've decided to build a CNC as well, I'll talk more in pictures than in writing
because my English isn't that good. so, sorry for my english
I'm not starting with the electronics and the motors yet, right now I'm just working on the mechanics
I made the bearing trucks from Iron, I haven't decided yet from what material the rest of the machine will be made.

A sketch of the bearing trucks


I'm not sure about Z, it looks too heavy to me.

A sketch with the lagers.


Iron



What should i use as the rods on which the bearing trucks will move ?
A profile, a square, or a cylinder ?



That's it for now, it'll take time until the next update as I'm going thru school now.

[damae]

EC, Fantastic job getting started! Your English is better than some here who speak it natively, so no need to be shy about writing.

What CAD software are you using? Is it Rhino perhaps? Your images are rendered in perspective mode, which makes me think it's not a natively CAD program. Don't get me wrong -- the perspective rendered images look great! I'm just curious, that's all.

Originally Posted by E.C What should i use as the rods on which the hinges will move ? A profile, a square, or a cylinder ?

It seems to me that you need to use the cylindrical tubing. In your current configuration, it looks like the square and angle tubing would run into your bearing mount in the corner.

What are your expectations for this machine? How big do you want the cutting area? What materials do you want to cut? How fast? If you figure out your requirements, we can help with feedback on that Z axis.

My opinion is it's not too heavy if you hope to cut some light aluminum. If all you want to cut is foam, then you might have more strength than needed. But as long as your motors can lift the axis, more strength is usually only good. =)

Keep us posted!

[E.C]

damae, its not me that wrote this
a friend of mine translate my hebrew to english
now you are going to read my english

i'm using SketchUp to sketch the parts.
i think that profile will work better, because it harder

picture's i take



of course i'll use iron and not aluminum

my cutting area probably will be 60*60 ~ cm
my expectations are - aluminum,copper(?) and Perspex
i dont care so much about the speed

my budget is low, real low. so minimum mony and maximum performance

[ViperTX]

Depending on the weight that will be supported....you may be better off with the steel square tubing, if you can get tubing that has a thick wall 3 mm or thicker.

[damae]

Originally Posted by E.C i'm using SketchUp to sketch the parts. i think that profile will work better, because it harder

I took a look at SketchUp. Very interesting software! I might try out the demo version.

I can see from your pictures that the square profile does fit without interference in the corners. If you use square tubes, however, you will have to mount them carefully to make sure they are rotated at exactly 45 degrees. That's a problem you don't need to worry about with a round tube.

Originally Posted by E.C my budget is low, real low. so minimum mony and maximum performance

Well, you've come to the right place then! This forum is full of people trying to do big things with very little money. They're also good at encouraging you to keep building.

[E.C]

i forgot to ask, do i need a special "screw" to move the hinges?
i mean stainless steel? zinc?
zinc will do the job?
like this (my old design, aluminum. garbage )

[chuckknigh]

Any screw will work, but there are thread profiles which are designed for this type of application.

What we call allthread is what you seem to have used. Standard hardware-store threaded rod, which has a triangular thread profile. This is adequate, but is the least desirable of the 3 designs. It is not designed for precision or efficient power transfer, but it has the major benefit of being cheap and commonly available.

The second type of screw is called ACME thread. If you have a vise (maul) you can look at its screw -- its threads will be kind of square. That's ACME thread. This type of threaded rod is made to a higher standard of precision, and the thread itself is designed to transmit power more efficiently. It's relatively inexpensive here in the USA...no idea how much it would be in Israel.

The last type of screw is one that uses ball bearings to reduce the friction. It's called a ballscrew and is a helical ball bearing on a precision rod. needless to say, it's pretty expensive, and is overkill for most of the routers on this site. Its primary benefits include greatly reduced friction and high power transfer efficiency. In other words, you need a smaller motor to do the same work.

Its other major benefit is that it is available in a level of precision that is unthinkable for the other types of threads. Here comes the down side...it's EXPENSIVE. It's worth the cost, if you need it...but be forewarned about the cost.

If I were you I'd start with the hardware store allthread, and plan ahead for an upgrade to ACME thread if you need it. It's amazing how well it works, even with the cheap stuff.

-- Chuck Knight

P.S. What shape is the profile on the side of those bearings? If it's round or a vee shape, then you might just run a single bearing along the edge of the angle iron...the groove will make sure it stays in place. If you wish, put a "stabilizing" bearing at right angles.

Might simplify your build.

[ViperTX]

E.C......could you change the terminology.....from hinges to bearing trucks, thanks.

[E.C]

chuckknigh, thanks. i'll use the "hardware-store threaded rod"
What shape is the profile on the side of those bearings?
i dont know yet, soon..

ViperTX, done