First Build 5 x 12 Steel Frame CNC router

[Scott Damman]

Some updates on the gantry

All of the bracing clamped in place ready for spot welding. The ballscrew is in place to set the distance between mounts.




Here is one of ballscrew mounts




this is the end of the gantry showing the space for the estop


This is one of the longer braces that connect to the ballscrew mount block




Here is the backside with all the bracing welded up


And the front side, notice I drilled some 1/2 in holes on the wrong side. My linear rails are threaded from the backside so I have to through drill from the back. The good news is I am welding on 3/8 plate (I drilled the holes to the correct spacing on the mill first and used the 3/8 plates as templates) on the front side where the linear rails are going to mount.

[sinnsvak]

Very impressed, with a lot of things. Very excited about your A-axis, sometimes one should just go to ahead and build it instead of pondering if it will work or not :D I have not attempted to build it yet, as I dont even have an idea of how I would use it. I really have no clue how one would incorporate 4 axis programming.

I would probably fit the widest possible belt there, if I were to use belt, you want the spindle to be rigid enough. What kind of bearings, if that is how you are pivoting the A-axis? Got any detailed view of it?

Nice work so far.

[Scott Damman]

What kind of bearings, if that is how you are pivoting the A-axis? Got any detailed view of it?

Nice work so far.

Thanks for the comments

Heres a view of the bottom of the Z axis and a section cut into it.




**sorry the drawings are upside down**


Here is the box tubing removed

The bearings are roller bearings that I can get from McMaster Carr easily. 1 1/4 diameter shaft. Bearings are designed to be held into aluminum housings bolted into the 3 x6 steel tubing. The shaft is a 6 inch threaded on both ends. Again something I can just order from McMaster. The bolts into the shaft allow me to put preload into the bearings. I was thinking of bolting the pulley hub (pulley is not pictured) to the spindle mount.

Open to thoughts on this design. I think it will work....

[Scott Damman]

A couple more updates sorry for the bad pictures
Drilled backside holes out to 1/2 inch to allow bolt and ratchet to be put through from the back. Im thinking I will just order a bunch of plastic plugs to put into these holes once I am done.



I threw a couple bolts into one of the linear rails just to see how things were coming together.



So far I am pretty happy with how the build is coming together. Time will tell if I have some precision/accuracy when im done...

Here is a ~bad video of me test running the used colombo 10hp ATC spindle that I got. Running it at ~18,000rpm after running at ~8,000rpm for 10 mins to get the grease moving in the bearings.

[Boyan Silyavski]

Very ambitious for a first build.

Some thoughts:

-the gantry legs dont seem adequate for the rest of the parts you will use on your machine

-the A may work for foam but i dont see it serious for anything more than wood

-the stepper motors , ok- the huge stepper motors, what drives will power them? 230VAC?

-that bracing may be was totally unnecessary. I dont see how that will strengthen anything. It could even make things worse, strengthening one point too much and not allowing the forces to spread uniformly and creating pressure points. So later all rings.


What will you be using this machine for? Remember- the weakest point is the criteria for how strong your machine would be. Again-the gantry legs.


PS:
That gantry legs will greatly benefit from bolting or welding on them 10mm steel plates in both directions, 2 per leg in total

[JAZZCNC]

Hi Scott,

This is how I see couple of not so little things.

Steppers:
Really Cannot comment if they will be good enough because you haven't said anything about what your using for linear motion on the X axis. I assume Rack n pinion but what ratio etc.? . . . But let me put it this way 550lbs or put anohter way 1/4 Ton is lot of Mass to Accel and stop so better get this correct or you'll seriously regret using steppers.


A Axis: You need to think again on this I'm afraid NO WAY will Stepper with such small ratio hold that Big spindle at angle without moving or vibrating.
Remember the Z axis is the MOST important area on machine so weaken this and all that OTT work you have done on the frame is pointless.

[Scott Damman]

Very ambitious for a first build.

Some thoughts:

-the gantry legs dont seem adequate for the rest of the parts you will use on your machine

-the A may work for foam but i dont see it serious for anything more than wood

-the stepper motors , ok- the huge stepper motors, what drives will power them? 230VAC?

-that bracing may be was totally unnecessary. I dont see how that will strengthen anything. It could even make things worse, strengthening one point too much and not allowing the forces to spread uniformly and creating pressure points. So later all rings.


What will you be using this machine for? Remember- the weakest point is the criteria for how strong your machine would be. Again-the gantry legs.


PS:
That gantry legs will greatly benefit from bolting or welding on them 10mm steel plates in both directions, 2 per leg in total

Hi Scott,

This is how I see couple of not so little things.

Steppers:
Really Cannot comment if they will be good enough because you haven't said anything about what your using for linear motion on the X axis. I assume Rack n pinion but what ratio etc.? . . . But let me put it this way 550lbs or put anohter way 1/4 Ton is lot of Mass to Accel and stop so better get this correct or you'll seriously regret using steppers.


A Axis: You need to think again on this I'm afraid NO WAY will Stepper with such small ratio hold that Big spindle at angle without moving or vibrating.
Remember the Z axis is the MOST important area on machine so weaken this and all that OTT work you have done on the frame is pointless.

I think you are talking something along these lines for the sides of the gantry legs? I was wanting to do FEA on these legs but never got around to it, I did however do calculations (free body diagram) to try to calculate total deflection based on 1000lb force at the bit and keeping the total deflection ~3 thou at full load.

I could go higher with the bracing as well this is just a quick drawing.


The thinking behind the bracing was to connect the upper and lower gantry beams. I used box tubing between the beams. Now the rear bracing, the thought there was to reduce the twist in the gantry. Hopefully it doesnt cause issues...

So the A axis, this is exactly what I am worried about, holding it in place when at angle and also moving it. The A axis would really only be used when machining foam blanks for paddle boards. However since I want to be able to machine wood, and aluminum as well then I really need to make sure this thing is right.

Couple things I am thinking thoughts are greatly appreciated.
- Eliminate A Axis...
- greatly increase the belt ratio
- keep A Axis but have an air operated taper pin that holds it at 0 when machining wood/alum
- look into a harmonic drive rather than belt drive

X drive
I was planning on using rack and pinion with a pinion of 1 inch I was going for 4:1 ratio to the pinion.
so 3.14 inches per revolution of the pinion, 0.785 inches per motor revolution, works out to 0.0039 inches per step. I was thinking of micro stepping them x10 = 0.000395inch per micro step.

I am brand new to this and trying to learn what feed and rapid movements I need to shoot for to cut wood/aluminum properly. I know it depends on the number of flutes on the bit etc. Am I crazy to think I should shoot for 1000ipm?

The motors I have are chinese 1841 oz/in with MA860H drivers along with 60V drives. Based on the questions it sounds like these are not adequate?

Servos
So if scrap the steppers for X axis then im looking at servos. Something I am even more NEW to than steppers. I need to do more learning on how to size them please correct where I have errors!

Things to keep in mind when sizing?
Gear ratio - want to keep the servo motor spinning at higher speed to stay in its power range - unlike steppers which have the most power at 0 speed
Load to motor inertia, this one I have seen 10:1 ratio but I dont really understand how to use that

One thing I dont understand, when X is not moving what is holding if from moving? I had assumed that the steppers hold the load from moving at 0 speed (is this the case with steppers?). If that is the case what is doing the holding when using servos?

Can my router have both steppers and servo motors? I think the stepper would still be adequate for the Y Axis and could use one for the Z axis (as Im sure I can not send them back)... I plan to use ethernet smooth stepper with mach4.

Got the X axis steel drilled these needed to be through drilled as well since the linear rails are bolted from the back. 244 holes!!!!



Any help with servos for this size of gantry is greatly appreciated.

[mekanik]

Hi Scott
I don't have any experience of the 4/5 axis machines but i would imagine that the "A" axis you are trying to emulate would be a wheel & pinion mechanism.
Regards
Mike

[Tom J]

I fully agree, legs has to be revised.
I make another desktop router with fixed gantry this time and see how I made it:

all made from rectangular profile 50x25x3
I weld everything with Tig this time will start new topic about my build
Good luck
Tom

[Scott Damman]

I have been MIA for a long period, normal life and other projects got in the way over summer. Finally back to working on the CNC.


Leveling the Y to Z plate for gantry foot epoxy pour

Pouring the gantry feet

Ballscrew to Z axis plate, made with steel I had on hand

Installing limit switches for Z

Z home Prox Switch

Finished underside of Z axis with dust shielding in place

Z axis installed onto Y axis/gantry

Lots more Z axis mockup

Building brackets for dust collection holding and pneumatic counter balance system

Machining and installing guides for dust shroud, shroud/brush will be on pneumatic cylinders so it can be pulled up when needed and also when I add the tool changer.

As it sits today, my plan is to work backward from the Z axis finishing each axis as I go. Sorry for the dump with little text but I wanted to update this with where things are. I can give any specific information as needed