[linkreincarnate]

I think I'm in way over my head here so I could use some help!

My idea is to build a cnc tool platform for various types of manufacturing and machining jobs.
I want to create a cnc router that can detach from a lower base and mill objects larger than the machine's footprint by simply moving the machine after each job. It would have a detatchable spoilboard and be able to reach below bottom of the upper frame for concrete milling etc.
I also want to use this same platform as a large scale 3d printer.
I have 1 meter ballscrews and fully supported 16mm linear rails and I am hoping to maximise build area using these parts.

I hope to be able to mill .5 inch aluminium plate. 7075 would be nice but I'll settle for 6063-4 (I forget which is which)

To top it off I have already run over my budget so I have to finish it on the cheap.

Yeah, I want it all, I know...

So far my idea is to build a full cnc machine that sits on top of a table with extended range on the z underneath the upper cnc machine. This would mainly be for z height when 3d printing but some of it could be used for milling things that don't fit in the upper part's z build height.

Here is my frame layout so far.https://drive.google.com/open?id=0B9...tnLUxacmM0Q2Y4

So, onto my many questions.

1. Is 20-4040 too flimsy or will the added rigidity of fully supported 16mm rails be ok for milling aluminum?
2. Will those aluminum joining plates do the trick?
3. Are there cnc transmission gearboxes for changing speeds?
4.Can I double up these stepper motors on one of these drivers AND use it with the smoothieboard?
5.That's not helpful Gerry...
6. Where can I get gantry plates cut that wont break the bank?
7. What thickness and material should I use for the gantry plates?
8. Should I scrap the oper box and replace it with welded steel s-3 i beam?
9. How much would it cost (ballpark) to get those ibeams welded into a frame and drilled so I can bolt everything to them?
10. Would that be enough?
11.What kind of speeds should I expect to be able to get out of this?
12, (I'm aiming for 200mm/s under no load for 3d printing applications) What do I need to change to get there?
13. Is there a swwet spot for motors that can run fast under little load but still provide enough torque for what I need to mill?
14. In the current frame design, where should I put all that extra 20-2020 and 20-2040 to stiffen up the frame the best?
16. Is that power supply enough?
17. I currently plan to use the linear rails on x and y axis and the openbuilds linear actuator in the bottom box (attatched to the crossbeams). Is that the best layout or should I consider something else?
18. Are there any other major parts that I need that I haven't already got? (Besides gantry plates)
19. Any parts I should return for something better? (I have about a week left in my return window)



I don't expect anyone to answer all of these questions but if any experienced people could pick one or two to answer that would make my day.

Thanks for any help you guys decide to give me.




My parts list so far.

Stepper Driver:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1


Stepper:
3 of Nema 23 CNC Stepper Motor 2.8A 178.5oz.in/1.26Nm CNC Stepping Motor DIY CNC Mill


NEMA 23 Stepper Motor - OpenBuilds Part Store


Spindle and Controller
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1


Spindle Power Supply
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1


Linear rails x 4
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1


Linear Bearings x 8
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1


Ballscrews x3
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1


Framing
14x 20-4040 2440mm
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1


6x 20-2040 2440mm
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1


6x 20-2020 2440mm
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1


Hardware:
L Joining Plate x 25
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1


T Joining Plate x 25
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1


Cross Joining plate x5
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1


Tnuts:
M4
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1


M5
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1


M5 Economy
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1


M5 Drop in
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1




M4 Bolts
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1


https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1


M5 Bolts
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1


https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1


https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1


https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1




Corner Brackets x 50
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1


Other Corner Brackets x 25
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1


Internal Channel Anchors x20
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1


Interface Board/ Controller Board
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1


GUI Control Panel
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1


Main power Supply
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1


Linear Actuator Bundle
http://openbuildspartstore.com/c-bea...tuator-bundle/




Frame Layout.


https://drive.google.com/open?id=0B9...tnLUxacmM0Q2Y4

Future Planned Addons
Vacuum Forming
4th axis and tailstock
Laser Cutter
3d printer.

[ger21]

[QUOTE]5. Is this just a pipedream?[/QUOTE

Yes. I stopped reading at this point.

[kdoney]

I assume you have SOME skill when it comes to fabrication since you are going to use the machine for fabricating. I would suggest you build your base out of tubular steel welded together. It is VERY much cheaper and much more vibration absorbing. The spindle you're thinking of is way too small and once again much more expensive than a simple router. Round linear rails are crap. They allow the system too much movement in critical axes. If you can't use recirculating square bearings

http://www.automationtechnologiesinc...inear-guideway

then I would suggest v bearings and rails. You can find the builds on cnczone.com

The ball screws are fine but I would try geared down rack and pinion first to see if you can save some money. If it doesn't work you can use the rack and pinions on something else later.

[linkreincarnate]

Do you think you could show me where my expectations are unrealistic? That response gives me nothing to work on.

[linkreincarnate]

Not really. I am a software developer by trade. I'm not dumb, but I really don't know what I am doing here.

Also I have no welding experience so that is why I chose 8020.

So the todo list is to scrap the spindle and linear rails.
Get a welded frame.
How much should I expect to pay for a box like the one I modeled up made out of suitable square tube steel?

[mactec54]

linkreincarnate

Your spindle and control is never going to cut aluminum very well, if at all, they are not a real spindle, but just a DC motor with a collet chuck on, a very poor choice 1.5Kw would be the minimum for your spindle

You would have to show how you plan to build the frame, where the rails are mounted Ballscrews Etc

Steel tube may make it to heavy to move like you plan, but 8020 would also have to be selected carefully as well, as not all works for these machines

[ger21]

A 3D printer and a machine for cutting metals are two VERY different machines. Attempting to build a machine that does both will not do either one very well.
Then you mention concrete milling???

A machine capable of cutting aluminum at a reasonable rate would need to be built from steel, or the biggest extrusions you can find. It would weight far too much to make it portable.

You could use a dremel as a spindle for what you're proposing, as it wouldn't be rigid enough to remove material much faster than a dremel.

I suggest looking through a lot of the threads here, to see what other machines look like. Look at machines from manufacturers.

It looks to me like you've been looking at 3D printers, and assuming it's a small step to go from a 3D printer to a mill. The reality is that a printer needs to be about 100x more rigid to be useful as a mill.

You mentioned 200mm/s, which is 12m/min. That would be 2400rpm. With good steppers, really good drives, and a high voltage power supply, you might get 1200rpm. At that speed, that ballscrew will be whipping like a rubber band.

I generally tell people looking to build a standard machine to spend a few months reading and learning. When you want to build something nobody else is doing, you need to add a lot of trial and error on top of the few months of reading.

[mactec54]

I assume you have SOME skill when it comes to fabrication since you are going to use the machine for fabricating. I would suggest you build your base out of tubular steel welded together. It is VERY much cheaper and much more vibration absorbing. The spindle you're thinking of is way too small and once again much more expensive than a simple router. Round linear rails are crap. They allow the system too much movement in critical axes. If you can't use recirculating square bearings

then I would suggest v bearings and rails. You can find the builds on cnczone.com

V bearings are a poor choice, what he had are much better, not the best, but better than any V bearing setup

[linkreincarnate]

Honestly I kinda suspected all that. I was getting the sinking feeling that I had just dropped too much money on the wrong parts. Oh well. I'll find an alternative use. Thanks for taking the time to point it out.



Is there any sort of build that would be suitable for the parts I have? I'd really like to be able to cut plates for gantries and such.d

[linkreincarnate]

A machine capable of cutting aluminum at a reasonable rate would need to be built from steel, or the biggest extrusions you can find. It would weight far too much to make it portable.

Even thinner softer aluminum? Ok, maybe I cant cut half in thick aircraft aluminum (that was kinda a joke anyway) but I cant manage 1/8 inch 2011 with this? Not even over a long jobtime? I've seen videos op people cutting aluminum with far less that what I have on the openbuilds forum. I'm not all that concerned about how long it takes as much as I am with accuracy (even there I onlly really want to get to .5 mm) I thought I was overbuilding compared to what they do.

You could use a dremel as a spindle for what you're proposing, as it wouldn't be rigid enough to remove material much faster than a dremel.

What if I threw a dewalt 618 on there and only used this spindle for fine detail work like engraving? Would that work?

It looks to me like you've been looking at 3D printers, and assuming it's a small step to go from a 3D printer to a mill. The reality is that a printer needs to be about 100x more rigid to be useful as a mill.

I did come from 3d printers.
I dont really want a mill so much as a light duty cnc router for wood plastic and aluminum. I thought aluminum may have been a stretch but from the sound of it all this could is is plastic.

I am aiming for a tier above ox builds or shapeoko and the like.
Did I at least hit that goal?

Are those hobby level cnc's that bad?

[zeeflyboy]

To me it all depends on expectations. There is a difference between being able to cut aluminium well with good surface finish and being able to cut aluminium in the most simple sense.

I have managed to cut alu on my first CNC which was small, mostly made of cheese and had nema17's and a proxxon router (dremel type thing) with acme screws and a fair bit of backlash... there are plenty of videos of shapeokos and the like cutting aluminium too.

Biggest issue with cutting alu is that it needs a fairly brisk feed rate, it's not a material that responds well to babying with slow feeds as it rubs, heats up and then welds itself to the cutter. With a machine that's lacking rigidity that pretty much means you end up with having to take a very shallow cut, which in turn wears out the bit more quickly as it is only using the very tip to cut across many passes.

The other thing that lack of rigidity will bring is a poor sidewall finish as the tool chatters against it (also again shortening tool life).

The smaller the machine, the easier it is to make it rigid. You need to weigh up what work size area you really need or want vs the extra weight and cost of bigger extrusions/steel to maintain rigidity. I would also say that if aluminium is even remotely on your to do list, save up a bit extra and go for proper HGR20 linear rails and carriages.

Your speed expectations are off imo. I have some leadshine easy servo nema 23's with 1605 ball screws and 6,000mm/min is comfortable enough. I would suggest to hit 12,000/min you would need 1610 ballscrews, but then you are losing precision and torque. Bear in mind acceleration of a big ball screw and gantry will be no where even close to what a proper dedicated 3D printer will achieve. Personally I'd probably forget the idea making it a dual purpose machine... if you build it as a semi-decent mill it will make a poor 3D printer and vice versa.


The spindle is also a bit crap. The chinese 1.5kw or 2.2kw are decent for the money imo with low runout and quiet operation with water-cooling. If noise isn't an issue then a Kress is a good alternative choice.

What parts have you already bought?

[linkreincarnate]

I have all of those parts currently. It's okay though because I really needed some building supplies to tinker with. What would you say I still need to buy to make this a useable machine for wood and .25 inch aluminum. (If that is still too much how about for 1/8th inch?)
I'm fine with dropping the 3d printing side. I can also buy a dewalt 618k. What layout should I go with if I really want to keep as much build area as possible and would like to make some of my own plates for other cnc/3d printer builds?

Is this spindle kit ok?

https://www.amazon.com/gp/product/B0...A16P4TUM521SQ8

Is 110v even nessesary? Is there a way to get a 220v spindle what it needs without rewiring my house? If not, have any links to something similar that is 2.2kw and uses 110v?

Also I really like the idea of an open bottom. Is that idea salvageable? Maybe I wont be doing concrete engraving with it but I'd still like the option to work on larger that my build area peices.

Can steel I beam be welded and drilled? Could I build this with 4 steel s3 3 inch Ibeams miter cut and welded together?

What effect does the spindle runoff have on the final part? What is considered a good runnoff for a spindle? Bad?

[zeeflyboy]

You can get that sort of spindle in 110v too - just have a search.

They are a bit high rpm for aluminium really (thus requiring a fairly brisk feed rate - back to the old rigidity conversation!), but with single or 2 flute cutters I've found they do a great job and they have nice high rpm for cutting FR4, CF and the like.

I don't really think the thickness of aluminium is particularly relevant other than how long it will take you to get through it and what length end mills you can fit. It's not like you are going to plough through at full depth on a machine like this so it just becomes a question of how many passes you'll have to do (and also consider that chip evacuation becomes progressively more difficult the deeper a slot gets - if you are limited to relatively narrow end mills due to having a weak machine you may need both multiple vertical AND lateral passes to avoid the slots becoming too deep in relation to their width...). In that sense depth of whatever material is more a time consideration than a hard limit until you start to struggle to get a long enough bit that can also keep it's rigidity (the longer the tool the higher the deflection)

I'm certainly not the best placed to offer you solid advice - there are guys much more experience than "amateur hour" me, but for what it's worth these are my thoughts:

You need a moving gantry design if you are going to have your hope of a pick up and drop machine with an open bottom. One issue is that I think you are planning a good span of 1 metre or more on the X-axis gantry so you might want to consider dual motor and screw design for the Y axis (or at least dual screw). Picking up and placing the machine will probably mess with the alignment... if you are okay with that then no problem. I would definitely want to add corner bracing to try and keep the thing at least roughly square though.

I don't really see any reason why you can't have a machine that can reach through the base to the bottom as long as you aren't after too large a clearance height on the gantry for the normal bed. For example my machine currently has a gantry clearance of roughly 150mm - it would be very simple to just shorten the arms and then have say a gantry clearance of 100mm and be able to place the spindle 50mm "beneath" the bed with an otherwise identical design. You will obviously need to give a little thought as to how you will secure the machine on the material though.

Anyway, you will definitely want more than a 40x40 beam for the gantry. Triple that and its more reasonable.

Really I think you just need to rough out an actual design idea and then ask for comments on it. Just showing a frame creates a lot of unknowns and leaves other people to essentially try and design your machine for you. At the end of the day I get the impression this is mostly a fun project for you, as mine are to me, and a good part of the fun is in the building of the machine itself as much as the using of it... in that sense I think just have a crack and see what you can come up with - since you already have a lot/all the parts you don't really have much to lose.

Once built you will quickly see the limitations and ways to improve upon the design.

[linkreincarnate]

Ok I am going to redesign a new cnc for 4x8 milling using a welded steel frame good bearings ect ect.

But until then I'd still like to assemble what I have here into a working cnc that can cut plywood. Is what I already have enough to cut plywood?

[jckstrthmghty]

Ok I am going to redesign a new cnc for 4x8 milling using a welded steel frame good bearings ect ect.

But until then I'd still like to assemble what I have here into a working cnc that can cut plywood. Is what I already have enough to cut plywood?

The short answer, yes. If you have done your homework you know many have built tables based on MDF and gas pipe with success. It would be an understatement that there is a lot to learn. Start smaller. 8x4 is not what you want as your learning build. My suggestion is to read many of the build threads here before you turn a bolt.

[wizard]

I think I'm in way over my head here so I could use some help!

My idea is to build a cnc tool platform for various types of manufacturing and machining jobs.

You can build a router, a lathe, mill or a 3D printer but one machine can't be all of them. At least it won't do all of the jobs very well.

I want to create a cnc router that can detach from a lower base and mill objects larger than the machine's footprint by simply moving the machine after each job. It would have a detatchable spoilboard and be able to reach below bottom of the upper frame for concrete milling etc.

You are way off course here. This especially if you don't have machine tool background.

I also want to use this same platform as a large scale 3d printer.

This isn't reasonable.

I have 1 meter ballscrews and fully supported 16mm linear rails and I am hoping to maximise build area using these parts.

I hope to be able to mill .5 inch aluminium plate. 7075 would be nice but I'll settle for 6063-4 (I forget which is which)

To top it off I have already run over my budget so I have to finish it on the cheap.

Realistically you have to start over. You need to confine yourself to one machine possibility at a time.

Yeah, I want it all, I know...

You won't get it.

So far my idea is to build a full cnc machine that sits on top of a table with extended range on the z underneath the upper cnc machine. This would mainly be for z height when 3d printing but some of it could be used for milling things that don't fit in the upper part's z build height.

Here is my frame layout so far.https://drive.google.com/open?id=0B9...tnLUxacmM0Q2Y4

So, onto my many questions.

1. Is 20-4040 too flimsy or will the added rigidity of fully supported 16mm rails be ok for milling aluminum?

For everything you want yes way to flimsy. Doable for a 3D printer though.

2. Will those aluminum joining plates do the trick?

Nope. Again of machining aluminum, at least to a degree i would find acceptable you need a much more robust frame.

3. Are there cnc transmission gearboxes for changing speeds?

You can find spindles with built in gearboxes. You won't like the prices though.

4.Can I double up these stepper motors on one of these drivers AND use it with the smoothieboard?

Nope.

5.That's not helpful Gerry...
6. Where can I get gantry plates cut that wont break the bank?

A machine shop. If not a machine shop your garage. Really it depends upon the plates you want to create. In most cases you are better off with box sections anyways.

7. What thickness and material should I use for the gantry plates?

It depends upon the overall design.

8. Should I scrap the oper box and replace it with welded steel s-3 i beam?

What in hell is an oper box. As for I-beams they are terrible solutions for structural components of a machine tool.

9. How much would it cost (ballpark) to get those ibeams welded into a frame and drilled so I can bolt everything to them?

If the welder has a boat payment coming due it might cost you a bit more than average. That being said you don't want to be using I-Beams for most parts of the machine.

10. Would that be enough?

Enough for what?

11.What kind of speeds should I expect to be able to get out of this?

You don't even have a mechanical design yet.

12, (I'm aiming for 200mm/s under no load for 3d printing applications) What do I need to change to get there?
13. Is there a swwet spot for motors that can run fast under little load but still provide enough torque for what I need to mill?

In general you can implement all sorts of drive systems to get you speeds that are blindingly fast. Those would not be economical

14. In the current frame design, where should I put all that extra 20-2020 and 20-2040 to stiffen up the frame the best?

You are spewing way under what I would consider to be minimal materials if I was to use T-Slotted aluminum. Given that I wouldn't recommend using T-Slotted aluminum at all, for a machine designed to machine aluminum. For one it is way to expensive and that is just for the extrusions. Second it isn't strong enough nor heavy enough. Third to hold tolerances suitable for machining aluminum you really should have machined mounting surfaces for your linear rails.

16. Is that power supply enough?

It is too early to worry about really.

17. I currently plan to use the linear rails on x and y axis and the openbuilds linear actuator in the bottom box (attatched to the crossbeams). Is that the best layout or should I consider something else?

It depends upon what those parts are. Most linear actuators are crap for use on a machine to mill or route other materials. I work extensively in automation and many of the actuators we use can be extremely accurate when run with in their design limits but they couldn't possibly hold up to real machining loads. I'm not even going to bother looking at the open builds actuator as most of the respectable actors out there suitable for this sort of use are rather expensive.

18. Are there any other major parts that I need that I haven't already got? (Besides gantry plates)

A panel box for the controls, a computer, software tooling and etc.

19. Any parts I should return for something better? (I have about a week left in my return window)



I don't expect anyone to answer all of these questions but if any experienced people could pick one or two to answer that would make my day.

Thanks for any help you guys decide to give me.




My parts list so far.

It is way to early to be thinking about parts.

Future Planned Addons
Vacuum Forming
4th axis and tailstock
Laser Cutter
3d printer.

[wizard]

Ok I am going to redesign a new cnc for 4x8 milling using a welded steel frame good bearings ect ect.

But until then I'd still like to assemble what I have here into a working cnc that can cut plywood. Is what I already have enough to cut plywood?

It really comes down to what you expect to of the machine. You might get good enough results for building a boat but maybe terrible results for fine cabinet making.

This might should like a cop out but expectations are a huge part of what makes a machine acceptable. It is no different in a modern machine shop where a owner will have dozens of milling machine to choose from. Buy the wrong machine, too little, for a job an you don't make money. Buy too much machine and you don't make money.

In all of your postings you really don't go into your expectation too deeply, I take it that this is due to your background and not really knowing what you want. We can help some here but if you really want to understand machining metals you should take a machine shop course if you can find one locally. In any event in all machining operations, even in wood routing, there is an advantage to rigidity in a machine. If you are a luthier working wood to one thousands of an inch you will need a more rigid and precise router than somebody spitting out trinkets. To be effective in aluminum you should look for ten times the rigidity that is acceptable in a wood router and that is a minimal standard.

As for the materials you got so far you might be better off focusing on a 3D printer or laser type machine. This is certainly a good way to get yourself started in machine tool building.

[linkreincarnate]

So I guess I should take some time to clarify. I understand that I came into this with unrealistic expectations of making a machine that does everything. I have decided to build a 4x8 machine as my second machine. This is the one that will cut aluminum. Those questions will come when I have bought enough steel beam to build a frame. What I am really asking about now is more like this; If I built as rigid a frame as I can out of the materials I listed earlier (Like an aluminum extrusion torsion box), would this be enough to do simple 3d carving and to create stuff with plywood? What if I used a fixed gantry design and accepted the smaller build area? What should I expect out of a cnc machine with the parts I have already? Would it be better than an x carve for example? Could it cut harder woods? I've got like 3 3d printers already, I'm not comfortable with a powerful laser in the house because I have a child. I'm really hopoing to make some stuff out of wood.



How rigid is rigid enough for woodworking?

For that matter how exactly do you measure rigidity?


Basically, if I build a machine using those parts, what could I reasonably expect to use it for?

[nummi]

4x8 machine is huge and needs to be very stiff and heavy for cutting aluminum. Don't buy steel before your design is finished.

Here is spreadsheet that I downloaded from some forum. Credit for who ever made it. You can compare different materials with different dimensions and their flex as gantry beam. Gantry is easily weakest link in many designs so it's good place to start comparing materials.

I recommend to take some design from this forum that is proven to be able to cut aluminum well enough. Then enter dimension to the spreadsheet and compare numbers to one you are planning. You can see quite clearly how much stronger peaces you have to use when scaling size even little bit bigger to maintain same stiffness.

[linkreincarnate]

This is perfect! Thanks a bunch.