Building a CNC router

[HomeCNC]

I had a very good weekend, I was able to get most of the frame finished. The detail work of fitting the ball screws and bearing will be coming soon. I wish Reid Tool would get my Ball screw and ball nuts off of backorder! It's been almost 3 weeks now.

[balsaman]

Great looking machine! Very nice. Keep the pictures coming.

Your shop is much too neat....could you mess it up a little before taking any more pictures...I am worried my wife might see it..

Eric

[E-Stop]

O.K. I'm jealous. I'm still at the beginning stages of putting everything into perspective. I might be analyzing things a bit too much. Or you just make it look simpler than it is.

[HomeCNC]

I’m also surprised about how easy it’s going together. So far I just been machining the bar stock to the proper length and then drilling the holes in the proper spot. (lots of tapping). It seems to be going together great! I did need to slot the mounting holes in the upper Y-axis rail to get it so the Z-axis plate was parallel to the gantry (I used my calipers to check the distance).

Balsaman – If you could only see what is behind the camera! I can’t back up any farther than where I took the picture, because of all the crap around me and on the floor.

[Zephrant]

Looks great- I have also been thinking about using a motor/spindle setup with R8 collets. Can you provide a little more detail there? Is the motor mounted to the movable potion of the Z axis? Will you be supporting reverse?

I was considering finding a used cheapo mill and taking the motor/geared-head assembly as well as the quill, and mounting it on the back side of my gantry. Then I could manually dial in the speed as needed, and use a quick-change R8 collet system to drill and tap as needed (I have a Tapmatic tapping head).

I was also considering using a stepper to drive the drill portion. Then I could create a tapping motion- Forward at a certain RPM, with a certain feed rate, then reverse and back out of the threads. A quick-change setup that replaces the router with this setup might be more feasible, but I'm concerned about the software control of the RPM. Anyone think I could use a 4-axis system to control the table + drill RPM?


Zeph

[balsaman]

I am wondering if a stepper has the speed/torque to do tapping.

Eric

[Zephrant]

Me too. I don't need high-speed tapping though, so 120 RPM would be plenty fast. I just can't see mounting a huge 2 HP AC motor (like what is on my Jett mill) on a CNC table. Too much mass to move around when the router head is being used.

Zeph

[HomeCNC]

This is the area of my design that I'm not sure about yet. My plan was to find a DC motor and run it with a SRC speed control. Use a 2:1 ratio to get around 5000 RPM. I have having trouble finding a DC motor that will not weigh so much and do 2500 RPM at 90 VDC. I will mount the motor and spindle to the Z-axis slide. My concern is weight.

I can always fall back on getting a standard router. I just wanted something that was not so loud.

[Zephrant]

Man, I hear you there... I'd like to be able to run the machine late at night when the wife is asleep, but between the router and the dust collector I'm afraid it will be too loud.

My Jet mill is so much quieter than the 2hp router. I would gladly sacrifice some cutting speed for a quieter machine though.

Zeph

[balsaman]

Use a flex shaft? Perhaps you could scrounge some parts off an old gas weedwacker....They have 1/4" flex shafts in them.

Eric

[Zephrant]

How about something like this:
Servo


800 oz-in of torque, 3000 rpm, 1.95 HP all for $50.

Hook that up to your x2 pulley system to get to 6k rpm, and you might be set. Or find a high-speed 1:2 gear box, and not deal with any belts.

Zeph

[HomeCNC]

What they don't tell you is it takes 230VAC to run that motor. Still could be an option.