My New 24x24 V-Groove Router Design Log

[BobWarfield]

Great series of log pictures, Widgit!

Lots to learn about building "larger than the mill" with the right fixtures and techniques.

May favorite thing that I missed until I started looking carefully is your "Giant Indicol of Doom". That thing made me chuckle!

It's going to be really exciting to see this mill in action. I like the big NEMA boxes like what you've got there. Maybe you'll want to build a table for the router that has the box integrated.

Knowing the Widgitmaster's proclivity to precision, I could see the table top being a 24" x 24" surface plate.

Cheers,

BW

[widgitmaster]

This afternoon I worked on the Y-Axis side plates, 1st I clamped both plates to the mill's table, and cut the long sides to a width of 12". Next I repositioned the vise at 90°. Then I used long soft jaws to hold the plate perpendicular to the mill's axis, and cut both plates to length. With the same setup, I drilled & c-bored six holes for 1/4" SHCS along with the two 3/16" reamed dowel pin holes.

Now it's time to spray some blue ink all over the plates, so that I can accurately scribe lines with my height gage. Next I pushed the plates through the band saw, removing the bulk of excess material.

After looking at the plates, I decided not to make any more fixtures! Instead I put my big angle plate on the mill, and dialed it in. When placing the angle on the mill, I made sure it was as far back as possible, allowing room for the plates and my height gage. Now I prefer to do setups like this, its fun to go back to basics!

When I milled the straight cuts in the plate, I used a 1/2" dia endmill. So by placing a .500 pin in the fillet radius, I can set my height gage to zero knowing my mark is .500 down. Then I mover to the other end of the plates, and adjusted the jack screw until the scribe line was inline with the height gage's scribe. Then I double checked it, clamped everything tight and used my small face mill to finish the blended surface. Then I flipped the parts and repeated the process.

After the parts were deburred, and the ink was removed, I used my little V-Block and a punch to align the dowel pin at 90°, then tapped them in slightly. Then I used my Mill's table as a solid surface for hammering the pins to depth.

Wow, after 11-hours of working in the shop, my new router is starting to take shape!

Widgit

[ClaudioG]

Looks like a pimped out Midi on steroids!

Coming along nicely.

Cheers,

Claudio

[FrankM]

Fantastic work
That Electronics box is not worthy of this machine .

Thanks for the inspiration Eric.

[widgitmaster]

Thanks Frank!


Now, I have a question to all regarding Stepper Motor Sizing!
The largest NEMA-34 stepper I have seen so far is 2550 Oz In.
Because of the massive weight of the Y-Z Axis gantry, I'm concerned about inertia causing the stepper to loose / jump steps!
What is the formula required to calculate the appropriate size motor for a machine like this?
All the sites I have looked at only confuse me even more!
As soon as all the parts are finished, and the motors are attached, I can get the total combined weight!

Widgit

I found this with Google:
http://www.controleng.ca/inertia-mass-calculator.htm
http://www.baldormotion.com/pdf/Line...ng%20Sheet.pdf
http://www.monachos.gr/eng/calculators/motor_sizing.htm
http://zone.ni.com/devzone/cda/ph/p/id/223

[FrankM]

I'm no expert but
2550 in OZ sounds like overkill

I made a machine 1ft square cutting area (for the most part inspired by your threads I only wish I could be 1/2 the craftsman ) , I'm using nema23 320in oz. 1/2-10 acme , Delrin nuts from you and I have not had any isuues with loosing steps .

[BobWarfield]

Widgit, Mariss Friemaniss (Mr. Gecko!) has a great and simple write up on motor sizing in the Gecko FAQ:

http://f1.grp.yahoofs.com/v1/IHfVR4h...ecko%20FAQ.doc

Sorry for that long ugly link. It's in the files section of the Gecko board on Yahoo:

http://finance.groups.yahoo.com/group/geckodrive/

You want the question on whether to use a stepper or servo.

His basic rule of thumb is:

Multiply the weight you are moving by the speed to get watts. A 40lb plasma gantry times 1000 inches per minute = 40,000. Now divide that by the "magic number" 531 and you get 75 watts. Mariss says anything under 200 watts can be a stepper. Anything over must be a servo or it won't perform.

You can look at your step motor's rating to see how it fares. He also describes how to get to oz-in of torque.

One thing about the monster big steppers (over 1000 oz in)--they don't perform all that well. They're limited to pretty low rpms. I can't imagine your machine needs such a big stepper though.

For example, Tormach's design document says they use 640 oz in NEMA34 steppers on their mill. I'll bet your router takes even less, but you could do a lot worse than to just bolt on some 640's.

Cheers,

BW

[widgitmaster]

Nice machine Frank!

Well Bob. I guess I should have asked this question prior to ordering them big stepper motors! Hopefully, I'll be able to exchange them!

I was really concerned about the massive weight that will become the Y-Z axis, but I'm willing to try some smaller steppers first!

Thanks for everything Bob!

Widgit

[widgitmaster]

This afternoon I worked on the two rail supports for the Y-Axis. While spin-polishing them in the lathe, I noticed there was a little bounce to them. So I decided to setup the lathe to turn them from on end to the other.
To do this, I had to remove my 8-station turret from the cross slide, and put the Compound slide with the Alaoris tool holder on instead. Next I put a small pin with a 60° point in the 3-jaw chuck, and a ball bearing center in the tail stock. Now it's been a long time since I've use the tail stock, so it needed to be adjusted before I start turning the two shafts.

The way I set the tail stock is to mount the shaft between the two points, driving one end with clamp-on drive dog. Then I took a light cut on one end about 1/2" long and set my DRO to zero. Then I took another cut on the opposite end at the same zero. After measuring the two ends with a micrometer, i could see that the tail stock was out .006"

So I placed a magnetic base on the ways, and put the indicator on the turned diameter near the tail stock. Then I set the indicator to zero, and used a hex key to move the tail stock .003" Then I repeated the process of taking small cuts on each end until both diameters were within .0003"

After taking a cut nearly the full length, it was necessary to remove the shaft, and flip it end for end. Then I finished the area that was under the drive dog, and polished the shaft with Scotchbrite and oil!

Now both rail support shafts are perfectly straight, and true to the dowel pin holes in the ends. This will ensure the Y-Axis travels perfectly straight & parallel to the rest of the machine.

Widgit

[widgitmaster]

Good News!
After sending an email to the people at HOMESHOPCNC, they agreed to ship three 600 oz/in NEMA-34 stepper motors and refund the difference!
Good people to deal with!
Widgit

[widgitmaster]

Another busy day in the shop!
Today I setup the mill to cut the long tracks on the Y-Axis rail supports.
First I decided to raise the assembly up off the table so I could get a micrometer under the rail, this was easy as I have several blocks nicely squared up for situations like this. After putting the T-nut and stud thru the end plates, I spent several hours just dialing everything in! It is necessary to do this, so the V-Tracks run parallel and perpendicular to the top plate. After everything was successfully dialed in, I took a nice 9/16" dia 2-flute end mill, and stoned a nice .015 radius on the points. This leaves a much better finish, and the fillet radius in the corner also looks better.
Then I dialed the center of the rails to the center of the spindle, and zeroed my DRO, now I can move from one rail to the other by selecting the tool # in my DRO.

Next I calculated the offsets, and set my depth. now I just watched as the table moved slowly from one end to the other. It was necessary for me to put my hand under the rails when the cutter was in the middle, just to absorb some of the vibrations. This worked out fine, and now the rails are finished!

Then I put the vise back, and started the setup for the side plates. The part-zero was way off location from where the mounting holes go for the two rails. So I had to slide the vise over, setup a stop, and extend the Ram just enough to reach the datum corner.

The mounting holes went in quickly, as did the dowel pin holes. However, the ball screws are not ready yet, so I don't know what diameters will be needed in the side plates. So I simply bored a .3000" dia hole on location. This will allow me to dial in the precision hole for later setups.

Everything that has pins in it went together really easily, and now this router is looking even better!

Widgit.

[.xXACEXx.]

lookin good widgitmaster! last pic looks a lil like ...a dad and son sitting , telling stories of when he used to be a production router in a great machine shop! ive saw some people write "build in alot of adjustment" but looks like every thing you have pinned in location is working well together also..i was just wondering why so much travel on "Z" ? ,i too am wanting alot of "Z" travel ,but alot of people say to only build what ya need,since i dont "need" a machine at all , i was wondering are ya going to use 9 inches for any particular job?.. or just the old "build it bigger" approach ? sorta like having a 6 inch long #3 centerdrill ..but needing one that is 7 inches long..lol