Collars

can you please specify how to connect the collar/nut and bearings to prevent the axial movement of lead screw. Do I have to put that next to the stepper motor /coupling assembling or on the other side where the lead screw comes out. Or is there any way I can make the flexible coupling rigid so it does not come out of the middle spider?

You would use a combination of bearings and collars to prevent your lead screw or rod from being able to move back and forth. Without it being able to move back and forth, you shouldn't have the couplings coming apart, because the motor is solidly mounted and unable to move as well. I will try to draw a picture using symbols, with a key to define what each part is. --CB|--------------|BC}{M - = Lead Screw or Rod C = Collar B = Bearing | = Wood, the frame of your machine }{ = Coupling M = Motor On the example above you could replace the collar on the motor side with one half of the coupling, putting it right upside of the bearing to hold it in place instead. Like this: --CB|--------------|B}{M You could also place the bearings on the inside as follows: ----|BC----------CB|--}{M

I am almost done with the book build Cnc machine, but when I run the motors from mach 3, the 1/2" coupling comes out of the middle spider (the joiner which connects 1/4 and 1/2" coupling. How do I prevent this?

The lead screw must be held in position axially. In other words, you don't want your lead screw to move back and forth at all. This is the only way the coupling hub that is attached to the end of the lead screw could be moving away from its coupling assembly. Depending on the lead screw that you are using, the combination of bearings and collars/nut keep the lead screw in place.

How do I secure the non-motor end of the lead screw for my 'Book' machine build? Does it just sit inside the bearing or do i use a nut to lock it in place? I did not see any instructions for this in the book.

Use a clamping collar (if you are using an ACME lead screw) or a couple of 1/2 nuts (if using an allthread) against the bearing to keep the bearing in place and make sure there is no axial play.

How do I keep the lead screw from moving back and forth?

The lead screw needs to be stabilized axially. The lead screw should turn, but not move any other way. The method to keep the lead screw stable is to use two bearings with ID (inside diameter) that match the diameter of the lead screw. The bearings are positioned before and after a stable structural part. A collar is positioned at one side of the bearing assembly and another collar, or end of a coupling is positioned at the other side of the bearing assembly. Additional Information: How many times do you need to turn the handle to move the lead screw 1 inch? Additional Information: For our 5 start 10 tpi, the lead nut will travel one inch with two turns of the lead screw.

Hey. I have noticed that you guys use roller chain to move x,y axis and a lead screw to move the z axis, can you please explain the motivation in short? Thank you.

Dealing with running our CNC machines with roller chain on the X/Y-axes and lead screw on the Z-axis, we chose this method due to functionality and cost effectiveness. We wanted to make the lowest cost CNC machine available for our customers without taking to much functionality and precision away from the machine. We wanted the accuracy and cost effectiveness to be surprisingly high, with our machines getting thousandths of an inch will be no issue, and having it at a decent price!