A new hope: Epoxy granite and steel.

[jarjar]

I do not, all I have is a hand drill and a dremel, I'm outsourcing it. The sheet metal cutting and welding. It's not more complex then a straight or a C plate. It's just a square steel tubing in the end. I've actually received a quote for the whole piece from the local shop EUR600 total for the thing.

What about the pretty much mandatory stress-relieving after welding, the precision milling/grinding for the rails, boring for the spindle body, milling for the spindle flange?

[hardenum]

What about the pretty much mandatory stress-relieving after welding, the precision milling/grinding for the rails

stress-relieving is in the quote. No under-rail machining, epoxy leveling them. If I were to have them machine all the required surfaces on it, might as well find a different hobby. Machining prices in germany are off the charts. One time I wanted to bring my 300x200mm aluminum heatsink for a shop to mill 3x 10mm wide 200mm long cannals on the underside for heat pipes, the quote was EUR2000.

boring for the spindle body, milling for the spindle flange?

You mean the cartridge? I'm not doing it from scratch. I'll be (or rather the shop will be) making a different drawbar for one of these https://ae01.alicdn.com/kf/H06429625...c015c524f3.jpg, and slightly modifying the spinning part on their lathe. You are right though, that is not a part of the quote above.

[jarjar]

Steel-filled epoxy molding against a surface plate, yes, that can work. But not epoxy leveling.

I meant the bore to fit the spindle and milling the mounting surface flat and perpendicular to the rails where the spindle flange will be bolted.

[hardenum]

I meant the bore to fit the spindle and milling the mounting surface flat and perpendicular to the rails where the spindle flange will be bolted.

This sounds overcomplicating? The mounting surface that will be touching the cartridge will be cut with a saw so pretty straight to me if you ask. I mean I'm not making swiss watches, I don't need that kind of precision.

Maybe also consider simplifying the shape of the columns, but in the end you'll be the one to build the molds.

A smart man once said "people should put more work into molds".

[pippin88]

It's a gantry style with a lifting z axis, no way to do belt drive the traditional way.



There are dedicated direct drive cartridges that have a hydraulic thing that moves the drawbar like these:
https://sc02.alicdn.com/kf/HTB1l9RHX...XXaC.jpg_.webp

The thought of modifying a $500 belt drive cartridge into a direct drive with a hydraulic drawbar fills me with excitement.

I don't understand why you cant have a belt driven spindle. Just put the motor beside or in front of the spindle instead of behind.

I'm not saying direct drive is a bad idea. I just suspect it will be difficult dealing with drawbar issues etc

[hardenum]

Steel-filled epoxy molding against a surface plate, yes, that can work.

This, thanks for this, another piece of puzzle for my project. Really cool idea, having a hardness gradient on the cast piece.

[JAZZCNC]

Jar Jar and Pippin are making some very valid points and If you are not careful you are going to waste a lot of euros.

You are over complicating the design around the spindle and underestimating the importance of precision required in surfaces, etc. The fact you haven't even considered or looked into Fixed gantry design or even understand how it works tells me that you haven't done enough research into what is required for the machine you require.

I suggest you STOP and go take a look at fixed gantry designs because it's the BEST design for the size of the machine you are planning to build.

[hardenum]

Jar Jar and Pippin are making some very valid points and If you are not careful you are going to waste a lot of euros.

You are over complicating the design around the spindle and underestimating the importance of precision required in surfaces, etc. The fact you haven't even considered or looked into Fixed gantry design or even understand how it works tells me that you haven't done enough research into what is required for the machine you require.

I suggest you STOP and go take a look at fixed gantry designs because it's the BEST design for the size of the machine you are planning to build.

I cannot build a fixed gantry, there is no way for me to mount the workpiece vertically if I went with a moving table. There would be no point in building any cnc if I can't mill all 6 sides of the work piece.

I have looked over hundreds of designs over the past half a year and only a moving gantry with a fixed bed with a cutout ala Datron allows me to mount the workpiece in all orientations.

There is another design, a horizontal cnc mill, that would allow me to mount the workpiece so that I can mill all 6 surfaces. But to be honest it looks quite daunting to go down that route.

The spindle choice is pretty easy though. One day your bank account is full, the next day it's empty. If I went with a motorized spindle, I'd be screwed if either of the components broke. Cartridge + motor is far safer if something were to brake and needs replacing.

I'm happy to be proved wrong though.

I was thinking of having the front mold piece machined instead of plates that are cast into the casting. Cast it after having everything aligned to the machined front mold piece. There is no way for me to transport the casting to a shop for machining after it's been cast.

By the way, I'm months, if not years, away from actually starting doing any of this work, so I really appreciate any and all insights!

[JAZZCNC]

I cannot build a fixed gantry, there is no way for me to mount the workpiece vertically if I went with a moving table. There would be no point in building any cnc if I can't mill all 6 sides of the work piece.

I have looked over hundreds of designs over the past half a year and only a moving gantry with a fixed bed with a cutout ala Datron allows me to mount the workpiece in all orientations.

Only a 5 Axis machine can allow you to cut on all 6 sides in one operation. If your meaning to re-fixture and cut the other 2 sides then that's easily fixed, it's called an Angle plate bolted to the bed. Because that's all the Datron is providing with it's cut out, it's just an inverted angle plate built onto the end of the bed.

Other than that there is no difference between Fixed or Moving gantry other than Strength and size, Both have their own strengths and weakness but in your working envelope then the Fixed gantry wins hands down if you are wanting a strong machine.

If you want to work on 5 sides in one operation then Bolt a 4th axis to the table, again this would work on both designs but the Fixed gantry will do it better because it's stronger.

The spindle choice is pretty easy though. One day your bank account is full, the next day it's empty. If I went with a motorized spindle, I'd be screwed if either of the components broke. Cartridge + motor is far safer if something were to brake and needs replacing.

I'm happy to be proved wrong though.

I wasn't meaning the choice of separate Spindle + motor, that works good, but more your implementation of it is too complicated. Also, the Z-axis design is narrow and weak which will make all the trouble you'll be going to a pointless exercise.
There are plenty of examples of ATC spindle setups, just about every Milling machine with ATC uses the same setup. You just need the same setup and just rotate it 90deg so it's at the side if you don't have the room behind the spindle.

Also, I'm not sure your choice of Servo motor is correct as it looks just like an axis Servo rather than a Servo spindle motor.?

These are just some of the things I'm meaning when I say you are going to waste lots of Euros because none of them is cheap and easily done wrong if you haven't thought about and planned every last detail.

Theory and Cad are great, however, Reality is a Mother - F@~ing -Bitch just waiting to slap your face and kick you in the Nuts who never plays by theory's rules and changes them to suit Her whenever she wants.

[jarjar]

If your meaning to re-fixture and cut the other 2 sides then that's easily fixed, it's called an Angle plate bolted to the bed. Because that's all the Datron is providing with it's cut out, it's just an inverted angle plate built onto the end of the bed.

I can see how this would be problematic if you want to mill on the side of long pieces that won't fit under the gantry. With a fixed bed the cutout allows the work piece to extend below the bed. If OP wants to do a lot of those pieces then the moving gantry seems indeed the way to go.

About the sawn surface to bolt the spindle on, I think this is a big no-no. I'm not talking about precision watch making, just basic good practice for mating surfaces. If the contact area is bad, you will lose most of the stiffness and also distort the spindle housing, possibly damaging the bearings very quickly.