[LeeWay]

I used 3060 80/20 as the backbone in my mill.
I had fully intended to fill them, but after initial testing and a few upgrades, it is still hollow.
Just didn't need filling. If it ain't broke.....

I used similar tramming aids as well. They work great.
Looking mighty fine.

[nateman_doo]

Granted its not broke, but do you get any resonance from the pieces? I already have the 4 vertical columns filled (the 45x90mm). I will work on assembling the gantry tonight. I have some 1/4" thick 2x2 hot rolled steel angle for the joints. I have lots of scrap pieces to aid in bracing. My bandsaw is going to be working overtime tonight.

[nateman_doo]

I was looking at your build. Its much nicer then my X2 build. You didn't have any resonance from the 2 80/20 sections? I am afraid because I am using much more 8020, and a considerably heavier spindle then the X2.

I will know more by the end of the day if I can finish a test setup of the gantry.

Edit: Still reading that thread. How the hell did you sheer a bearing in half?! I guess those gas shocks didn't work out too well? I use a counterbalance on my X2. I will do the same for this build. Have to find 200lbs of steel laying around and a place to suspend it.

[nateman_doo]

Just thought I would post the other thread that started with the table.

I started this build in SEPTEMBER 2011
http://www.cnczone.com/forums/bencht...ils_101_a.html

I couldn't believe I have been working on this machine for that long...

[nateman_doo]

I just found out the spindle head assembly is actually 120 lbs. Here I thought I was Hercules.
[ame=http://www.youtube.com/watch?v=_rXSjZChdm4]Introducing the Tormach PCNC 770 - YouTube[/ame]

[nateman_doo]

After a painful evening, here are the updates:

Used 2x4x6 blocks to true up all the extrude joints. Probably one of the best investments I have made, they have proved very valuable for so many aspects of this build

Cutting the extrudes:

Had to prop an extension to help hold up the long pieces.
2 more cuts to go...

Here is the outer frame of the gantry:



What is not pictured are the 2 additional extrudes that will go from left to right and the Z slab will then get bolted on, and the entire thing will get lots of reinforcements. I don't want to cut them until I ensure the frame is perfect. I can only cut those once They will be somewhere around 40" long, or just under that.

[nateman_doo]

After a painful evening, here are the updates:

Used 2x4x6 blocks to true up all the extrude joints. Probably one of the best investments I have made, they have proved very valuable for so many aspects of this build

Cutting the extrudes:

Had to prop an extension to help hold up the long pieces.
2 more cuts to go...

Here is the outer frame of the gantry:



What is not pictured are the 2 additional extrudes that will go from left to right and the Z slab will then get bolted on, and the entire thing will get lots of reinforcements. I don't want to cut them until I ensure the frame is perfect. I can only cut those once They will be somewhere around 40" long, or just under that.

[nateman_doo]

In my attempt to kill some time at work I started doing some calculations on the 1545 extrude. Using the formulas in the brochure, I used their worst case scenario calculations and got a deflection on edge of 0.005" with a 200 lbs load, and if I put the beams flat, a 0.042" deflection.

My math might not be what it used to be since college, but I plugged in the following numbers:

Moment of Inertia (given)- IX 5.6929 (beam standing up vs. IY=0.7097 laying flat)
Modulus of Elasticity (given) - 10,200,200 (lbs sq in)
Length - 42" beam
Weight - 200 (the load)

______ 42³ x 200_______ ... = ... __14817600__
48 x 10,200,000 x 5.6929 ..............2787243840

(not that scarey is it?) If you wanted to know a different beam length, you substitute the 42 for whatever length you want. For a different load, change the 200, and if you wanted to lay the beam down flat change the 5.6929 to 0.7097.

Now, that is a SINGLE beam at a WORST case pinpoint load dead center of the beam with ZERO support. I have 4 beams pictured above, and 2 (not pictured) perpendicular to those 4 holding the 200 lbs load. I still have a ton of bracing to cut. If that doesn't ease ones mind about this stuff, nothing will.


EDIT:
Using a different formula for even distribution of weight along an unsupported beam, I get 0.00287" deflection on a single 40" beam - one of the 2 actual beams (not pictured above) that the Z plate will bolt to. With 2 beams I estimate 0.00143" deflection without a single OUNCE of bracing.

So if I take the 0.005 deflection of a single beam and distribute it over 4 beams I get 0.00125 of deflection of those beams, add the 0.00143 of the 2 beams, and I get 0.00268" of deflection in all. I may or may not be doing that wrong, but again all worst cases without a single brace. Not bad right?

Just for S&G's I calculated a 3060 profile with a 200lbs dead center pinpoint load. That beast moves 0.0013" even over a 48" span.

[LeeWay]

I was looking at your build. Its much nicer then my X2 build. You didn't have any resonance from the 2 80/20 sections? I am afraid because I am using much more 8020, and a considerably heavier spindle then the X2.

I will know more by the end of the day if I can finish a test setup of the gantry.

Edit: Still reading that thread. How the hell did you sheer a bearing in half?! I guess those gas shocks didn't work out too well? I use a counterbalance on my X2. I will do the same for this build. Have to find 200lbs of steel laying around and a place to suspend it.

Are you talking about this thread?
http://www.cnczone.com/forums/vertic...ill_build.html

I don't get any resonance. If I had it to do again, I would fill them just because, but I don't see a reason to tear it back down to do it.


IO am not getting any emails from any threads at the Zone, so sorry for the late reply.

[nateman_doo]

Yup, that one. I just did a deflection calculation on your Z column. that stuff is insane. Just a hair over one thousandth of an inch deflection with 0 support over 48"

[LeeWay]

Yeah. For an aluminum spine, it is pretty good.

I am looking forward to your results as well. I am hoping you will be pleasantly surprised.

[nateman_doo]

I am very pleased. I hang on a single 45x90 extrusion thats in the front and I don't feel it move at all. I never did, even before I filled them all with concrete

I designed some angle braces that will mate the 4590 and the 1545. Also a gusset plate that will mate them to the pillars. Once I know I have those clamped in and dialed in properly, then I will start cutting the 2 beams that the actual Z plates will bolt on.

[LeeWay]

I'll tell you how you can test the deflection of an extrusion in the real world easy enough.
Support both ends close to the very ends.
Support a caliper underneath the center of the extrusion with the depth gauge extended and touching the bottom of the extrusion.
Zero it out there.
Start adding weight incrementally. I did this with mine and saw very little. Had 50 pounds of weights on it.
I don't recall the exact measurement, but it was less than the accuracy of the caliper.

[nateman_doo]

I put a machinist level on one of my extrudes, then I stood on it. The bubble didn't even register.

I spend all night marking, punching, and drilling almost 12 of these:

They mate a 4590 & a 1545 post. I have juuust enough hardware for them, but I will need a bit more for the 2 Z beams.

Speaking of levels:

yes, I leveled them. Why? Why not is the answer. Stepping on the beam didn't budge the level. Feels as stable as stepping on the ground.

[nateman_doo]

Side note... While I was doing the work to this machine I had my X2 cutting some stuff, and I realized why I was having problems with my machine. I was burning out the motors with a repetitive cycle that drive the motors back and forth for over an hour at 40ipm. The X & Z motors were SEARING hot. I tried placing a huge slab of copper on the X motor and that helped pull some heat off - but I had to keep switching copper plates. Then I just decided to turn the coolant on and put the nozzles on the motor. Think that did the most. My Z axis started acting up since it was the Z and X doing this rapid movements for an hour. The Z axis lasted longer because the head was counterbalanced perfectly (60 lbs head and 60 lbs weight), but the X axis had tighter gibs (another flaw with gibs in general) so it has to overcome that.

So what comes out of all this? I think I want to try to make a heatsink for the motors. Its an almost silly idea, but it would help the longevity of the motor to make the body of the motor from aluminum. Since thats not happening, at least a heatsink would pull heat off the body. Better then nothing.

[keebler303]

What drives are you using with your X2?

[LeeWay2]

Stepper motors can get hot with no trouble at all.
The temperature they actually are would be good to know. They can sit there idle and get hot as well.
The drives and how they manipulate the current has a lot to do with the temps too.

[nateman_doo]

hot enough that when I sprayed coolant on it, steam rose up. Couldn't touch them hot.
I will not allow them to get that hot again.

[LeeWay2]

That does sound a bit too hot.

[nateman_doo]

I love having a REAL computer in the basement. I can now do CAD, CAM, Music and all sorts of other stuff down here on top of CNC'ing

My goal today is to get a Z beam installed.