My very first build using mostly 80/20 extruded aluminum...

[gjhammer]

Hello everyone,

I am in the process of designing/building my very first CNC router that I plan on using mainly for woodworking. I have visited these forums many times and have found them invaluable but with no experience, have not contributed yet until now. I want my machine to be able route 2' x 4' sheets of wood with about 8" of Z axis travel.

Here is the core components of my machine so far:

Base assembly (X-axis):

• 2040 80/20 extruded aluminum frame
• 2 15mm Hiwin rails
• 4 15mm Hiwin blocks
• 1/2-10 60" single-start acme lead screw
• Delrin nut
• Nema 34 stepper motor (TBD)

Table assembly:

• 2020 80/20 extruded aluminum frame

Gantry Assembly (Y-axis)

• 2040 80/20 extruded aluminum frame
• 2 15mm Hiwin rails
• 2 15mm Hiwin blocks
• 1/2-10 48" aceme lead screw
• Delrin nut
• Nema 34 stepper motor (TBD)

Z-axis:
TBD

I obtained most of the extruded aluminum and Hiwin blocks/rails from:

http://www.automation-overstock.com/
http://www.automation4less.com/

I obtained most of the miscellaneous hardware from:

http://www.mcmaster.com/

I obtained the acme lead screw/nuts from:

http://www.precisiontechmachining.com/



Attached are pictures of my design so far. I will post pictures later of the progress building the machine later tonight.

[fortyonethirty]

Why did you choose to make the work table seperate from the rails that the gantry slides on?

[gjhammer]

First off, I am no expert as this is my first time building a machine.

I did the table separate from the base for several reasons:

• Keeps the sweep of the gantry contained with the base, no worry about outside objects interfering with the sweep.
• Just one of the designs for achieving a fully supported X axis (I referenced the web-site http://www.cncroutersource.com/build...nc-router.html)
• Allows me the flexibility of swapping out tables in the future, i.e. maybe a full t-slot table or other options

Just keep in mind though that the table will be fastened to the base. I'm always open to suggestions or pros/cons to my design.

[gjhammer]

Here are pictures of my build so far. The base is partially done, the gantry is partially done and mounted on the X-axis, and the table is done.

Note that not all the brackets for the gantry have all the screws in them to save time unscrewing them when I do some more work on the gantry.

[gjhammer]

I still need to do the following for the base assembly (X-axis):

1) Mount bearing blocks I am getting from http://www.precisiontechmachining.com/. I will provide radial support at one end and radial/thrust support at the other end where the motor will be mounted

2) Install acme delrin nut into bottom of gantry assembly

3) Install acme lead screw

4) Install motor mounts but I won't do this until I have the motors and couplings in hand. I probably won't do this until near the end of the build.

For the gantry (Y-axis) I still have ways to go.

[FandZ]

Hey man, glad to see your getting a machine together. Hopefully I can give you some good critiques. Inside tracks are generally avoided. With the tracks of your X axis on the inside there's a chance for some binding/chattering. With the linear components you plan on useing I doubt you'll have a problem with any racking but it won't be that hard to flex those X's side rails outwards. Also you can't use any cross supports. If you went for the outside you could use cross beams and really gain some anti racking strength.

Again if you went outside you could simplify the table top and stiffen up the machine. Having fixtures is great but you want to mount them on your table top. Once you get everything squared you don't want to risk ruining your alignment by remounting various table tops.

Other than that, the Y axis stepper mounts seem like a lot of effort and material. I'd try to simplify it but bringing in other materials.

[LEVONCNCDUDE18]

I've make my own stepper driver the interface is DB25 pin>> and my software is mach3..
any one try a usb converter ,do you think is it working ... What software can be converted to usb..

[gjhammer]

Hi LevonCNCDude18,

You might want to post your question to another forum. I am a newbie and I don't think I can answer your question.

[gjhammer]

Test

[gjhammer]

TIDBIT #1: For those people in the design process, you can get 3D models of most of the 80/20 profiles, parts, fasteners, joining plates, etc. at:

http://www.3dcontentcentral.com/3DContentCentral/

They can give you 3D models in many different formats so hopefully you can get them in a format your CAD system will support.

[gjhammer]

Hi FandZ,

Thank you for your critique! Anything I can do now to save myself problems down the road is great.

As far as deciding for an inside track versus an outside, can you help me understand why the outside track design leads to less binding/chattering. I'm not doubting you, just wondering for my own information. Is it because the inside track design would cause the Hiwin block to be pushed toward the rail while the outside track design would cause it to Hiwin block to be pulled away from the rail?

I did notice alot of the commercial CNC routers do have outside tracks or tracks mounted on top of the X-axis. So it is definitely something I will consider now before I progress any further.

As far as the Y-axis stepper mounts, I will definitely look at simplifying this part. Let me see if I can come up with some alternative designs.

[FandZ]

Hi FandZ,

Thank you for your critique! Anything I can do now to save myself problems down the road is great.

As far as deciding for an inside track versus an outside, can you help me understand why the outside track design leads to less binding/chattering. I'm not doubting you, just wondering for my own information. Is it because the inside track design would cause the Hiwin block to be pushed toward the rail while the outside track design would cause it to Hiwin block to be pulled away from the rail?

I did notice alot of the commercial CNC routers do have outside tracks or tracks mounted on top of the X-axis. So it is definitely something I will consider now before I progress any further.

As far as the Y-axis stepper mounts, I will definitely look at simplifying this part. Let me see if I can come up with some alternative designs.

In a nut shell it comes down to flex. When you spindle is machining on one side of your table, it'll act as a lever on the other side. Basically your whole gantry will be trying to twist out of it's railed confinement. That twisting action will cause a binding effect. The end result may mean you have to go slower on your cuts or else your X axis motor may loose a step, or it'll have a chatter effect, or worse may cause ribbed tool marks in your material.


By moving your rails to the top or outside, you free up the inside to run cross support beams. These cross support beams will also serve to support up your table top. So it's a win win situation.


I also saw you plan on using nema 32 steppers. I'd really recommend you look at nema 23 steppers and a gecko g540 driver. To make good use of a nema 32 motor costs a minimum of 2 to 3X more. You really are not going to be pushing around the kinds of weight where nema 32 is needed. Forgive me if you already have all that worked out.