Nuts; I'm thinking about my nuts

[Stevie]

Hi guys; had a wierd idea today while my lathe was running (strange how a mind can wander at work; heheh)

My crazy idea is to make the ball screw static; and make the ball nut spin inside 2 support brgs; I can drive the set-up with a timing belt; this will give a nice reduction and increase the step accuracy; I was thinking about it because I want to remove that lump (stepper motor) sticking out on the end of the table (X axis); I have already designed the Y axis stepper inside the main back support of the vertical slide (Z axis); now if the X axis stepper could be installed in the middle of the cross slide block; the machine would have a nice clean look

Any ideas on this you design guys

[balsaman]

That idea is also great for reducing shaft whip for high speed applications. That is why it is usually implemented.

E

[Stevie]

Yeah i guess so; i just found the thread about this very thing; so i guess strange thinking is common here

[h3ndrix]

Hey stevie,

Hey, I can gurantee that that idea WILL work. How do I know, well, the Bridgeport Interact 1 CNC we have here has the timing belt on the Nut of the ballscrew. The ballscrew shaft is stationary and its hollow. Its about 2.5" in diameter and the spindle shaft runs through it. So, the machine moves the Z-axis by turning the nut, instead of the ballscrew. How about that

Good luck,

h3ndriX

[Stevie]

what a great idea; running the ball screw shaft around the spindle; "spacesaver design"

[limbo]

If your main goal is just to have the X-stepper inside the machine you can mount it "inside out", next to the screw to the end panel, and use a timing belt and pulleys. This also serves as the flex coupler. Several machines here have this setup, including mine.

John

[Stevie]

Think Bridgeport style; kinda tough to hid a NEMA34 inside the table end; I was thinking more to enlarge the space under the X slide by moving the base and the Y down; as I'm still in the design stage it will be easy (till I start to weld a structure up)

[limbo]

Now I see what you mean At first I hadn't noticed that your post was in the Metalworking Machines section. Probably a tough job to free up space between X and Y and still keep everything rigid. Curious to see how you are going to approach it.

John

[Stevie]

Here is a screen shot of my revision in surfcam; I've punched a hole through the cross slide and moved the stepper into the space below the cross slide; the bracket to hold the stepper is not drawn yet; nore the pulleys etc; the gray round bar is the ball screw; the red bars support the NSK rails (light blue) the green is the cross sldie; and rearmost green is the rear support of the vertical spindle head; purple is the base block; I'm sure you can figure out the steppers; I'm sure as I had to just hollow out the cross slide and move the cross slide nut/ball screw only 30mm to the right; the metal version will be easy too

The only concern now is the small clearance from the stepper to the base block; I've only got 2mm; I'll just have to make sure no chips get in there

[Mr.Chips]

I really like the idea of not spinning the ball screw, solves a lot of problems such as whip.
Hager

[Stevie]

I just updated the image to include the moved Z axis stepper motor; I've decided to move them both; I'll mount the stepper on a removable plate set into the side frame of the back support
for the image I've deleted one surface to show the stepper in the new position

[Stevie]

I'm going to up-date the other thread about the mill project; I feel this one has run its course; as I found out its semi normal to rotate the nuts

please use this thread to reply http://cnczone.com/showthread.php?s=...4222#post24222