My New Gantry mill project

[KTP]

Dang Stevie, that is one huge slab of aluminum!

What do you do for thrust bearings on your ballscrew? (sorry if I missed a post on this earlier in the thread)

I want to make a large gantry mill soon (so my wife will not keep trying to cut large sheets of plywood on my Shizouka bedmill) and am not sure what lengths to go to on the ballscrew mounts. My mill will be designed around scavenged parts. I got lucky with a 2 inch diameter 9 foot long ground ballscrew and nut, brand new for $125 and 6 sets of 9 foot long 2 inch wide THK rails with 2 carriages per rail, brand new for $50 each...monster rails...they weigh like 100+lbs each....really too big, but oh well.

Anyway, following your design with interest!

[Stevie]

Hi Rick

Well there are angular brgs for all the ball screws; plus i have 2 reg rsr brgs on the none drive end
The ball screw is 10mm pitch for X and 20mm pitch for the Y-Z so 2-1 ratio on X and 4-1 on Y-Z
I want a 5mm advance for 1 rev of the stepper

The Slab is the first part I have had to buy as far as materials goes that was cut for me and not scrap (I do pay for the scrap) the slab was $400

[JavaDog]

Wow Stevie, this thing is going to be a monster when you get it finished.

That's pretty interesting about the wrap angle increaser, haven't seen that before - going to have to remember that when I order all my pulleys/belts for my machine. How did you plan/measure for the extra length?

[Stevie]

trial and error
I just hung the motor down on the belt i had and sorta guessed at the lenght of the plate

[JavaDog]

Originally Posted by Stevie trial and error I just hung the motor down on the belt i had and sorta guessed at the lenght of the plate

Ah, you got the belt first! Makes sense...

[Stevie]

The Z drive stepper and mount
This time I have to get the belt after the mounting; the wrap angle increaser is also a tensioner this time

another view
The actual ball screw bearing mount also is the hard stop for Z down; upper most stepper 5mm mounting screw is also doing 2 jobs; screwed into the 1/2" plate and sticking through for the tensioner/wrap angle

3 screws hold the mount to the ball screw bearing block; the 1" thick brg block is screwed with 2 x 3/8" cap heads to the Z slide; another 5/8" thick block supports the other end of the Z axis ball screw
The screw is 20mm pitch; so 4-1 drive for 5mm advance per rev of the stepper; which is 650oz/in hold

note; I cut quite a bit out of the 72 XL pulley both sides; helps increase the accel rate

[TimKoene]

Wow, I must say, this is going to be a great machine. You could mill anything with that! Great job!

[Stevie]

Thanks
I did get most of the Y axis drive done yesterday; new pics tonight

[Deviant]

fyi, I think Stevie needs to expand his house.

So that we can all come live with him.

*grins*

G'job on the machine.

Looking forward to additional pictures.

[Stevie]

Drive side; still needs the small pulley

Other side
The track for the Argus chain is now on
Stepper is mounted 1-2-3 blocks holding the Z up; belt is ordered

[Stevie]

Small update

Ok the spindle from a Dodge Dakota hlaf shaft; hows it going?
Well this is one tough mother of a shaft; the shaft has to be 55 rockwell and is tough on tools; it bends after every cutting; as the stresses come out
I machine a bit every couple of days; after now getting close to the 35mm for the main brgs and 30 for the offend; it has stopped moving; it's about 0.01 up for grinding
There will be 3 or 4 35mm 6007 brgs for the collet/fixed lenght tooling end
The 2 x 6006 will take care of the other end and take the drive loads

The Y axis drive is almost there too; I'll post pics tonight

[KTP]

Hi Stevie,

Not to hijack your thread, but how would you recommend going about making a small spindle for someone without access to a grinder (but I have a dv-59 lathe and a fairly large cnc vmc)? I want to make either an ER-16, ER-32 or maybe even a 5C type spindle for a small table top mill (I want a portable mill I can take places for demos, but larger than a sherline, and with ballscrews, etc.)

I was thinking about starting with a ER-32 extension collet with a 1 inch shaft (something like what they sell in Enco...they are about 7 inches long).