Newbie- New Mill build log, and looking for help

[hedgehog23]

hello everyone. this will be my build log , and from time to time ill look upon you guys for help and suggestions.


the mill will be built from steel. thk linear ways and ground ball screws (all from ebay)

iv started on the Y axis. thk 25 linear rails , and a ground ball screw 14-5 pitch

here are a few pictures.






the base has been machined all around and will be flat ground when i get it over to my friends grinder. one side of the base has a ridge/rail machined into it and will become the master ala 5 bears


for steppers i was thinking direct drive from

http://kelinginc.net/CNCNEMA23G540Package.html

G540 3 axis package (One G540 + Three
KL23H284-35-4B (1/4” Dual shaft with a flat) 387 oz-in + one KL-350-
48 48V/7.3A 115V /230V power supply: $494.95


please feel free to add comments or suggestions

[hesham morsy]

happy hunting for the rest of your part

[hedgehog23]

oh and for travel im hoping for

x = 15"
y = 8"
z = 15"

[hedgehog23]

i was hoping someone would chime in on my stepper choice. all my ball screws should be around the same size and pitch, and all with be ground.

is direct drive the way to go? I was hoping so to simplify the build and keep the cost down.

Enough torque? Options?

Thanks

[muddobber76]

What type of spindle do you plan on using? I am slowly doing a mill build myself. Depending on your setup, 380oz stepper may be lacking in torque for the z axis. The z axis column will get heavy very quickly, wich is good for rigidity but a strain on undersize motors. My build will be similar to yours in travel and I am going to incorporate both steel and aluminum to combat this. I am using 640oz for the z. Keep posting and we can work together. Good Luck.

[muddobber76]

Here is the spindle and housing I built. The housing is made from 7075 alum. and the collet is an ER32 design. It will be belt driven.

[jalessi]

Hedgehog23,

What is the TPI of your ballscrew?

By looking at the picture of your ballscrew some sort of reduction will be necessary.

Pulleys and belts are very inexpensive.

Add an additional 20-30 dollars per axis will be money well spent.

Bigger motors = bigger stepper drives.

Jeff...

[hedgehog23]

5mm lead

and im not sure about the spindle. i was thinking of making it removable so i could use a router and a mill head from a mini mill. but i like the looks of the homemade job.

[hedgehog23]

Originally Posted by muddobber76 What type of spindle do you plan on using? I am slowly doing a mill build myself. Depending on your setup, 380oz stepper may be lacking in torque for the z axis. The z axis column will get heavy very quickly, wich is good for rigidity but a strain on undersize motors. My build will be similar to yours in travel and I am going to incorporate both steel and aluminum to combat this. I am using 640oz for the z. Keep posting and we can work together. Good Luck.

i plain on using aluminum as much as possible. where ever i wont need to grind. iv also read that others have used larger motors on the z axis

Thanks

[hedgehog23]

5bears went direct drive, any reason why i cant?

[jalessi]

Hedgehog23,

5Bears used really high end servo motors.

There is a big difference between a servo and a stepper.

Stepper motor torque falls off fast as the rpm increases.

You may get away with direct drive with light cuts, and small tooling.

The weight of your Z axis may also become a issue.

Jeff...

[hedgehog23]

are the timming belts zero backlash? i would think some backlash would be interduced with the belt.

what would be the minimum stepper size you would recommend for direct drive?

arie kabaalstra also used direct drive for his machine, although he did say small he would be machining small things, small cuts