Considerations for building a CNC.

[Anthon]

Making a CNC has been on my wishlist for some time now.
I make fender-tweed-style guitar amp cabinets (and finished amplifiers) and sell them online.  Currently, I do it old fashioned way, by using regular tools in my workshop, but it's just too time consuming.
Also, it would be nice if I could make aluminum engraved plates, enclosure and other stuff for DIY.

I wondered what would be a good design for carving multiple medium sized pieces of wood simultaneously  and precision milling and engraving of aluminum. So it must be big enough for woodwork, yet rigid and precise enough to make fine engravings on aluminum.
The machine has to have at least 150cm x 90cm working surface, perhaps more - as long as it doesn't compromise the precision.

I did some research, and I was thinking about ripping off Probotix Nebula. It seems like a pretty straightforward design with minimum of custom parts.  (which I could make out of thick plywood for the prototype, and then machine them out of aluminum once the machine is finished  ;D ).
It uses ballscrews and supported rails for maximum rigidity.

I could spend 1.5-2k euro on parts, considering I already have a ton of 4x8cm aluminum extrusions, and some smaller ones (also not including spindle,PC, dust extraction).

Any other suggestions?

 

[totoxraymond]

Hi Anthon,

Take a look at the open maker machine. These are sold in kits by a fablab in France. Open source and very diy friendly. Theu have different versions and I think it's easily customisable.

http://www.mon-fablab.fr/openmakermachinepro/

In fact, it's based on the reprap project, so the custom parts can be made by the machine itself.

Cheers,

Thomas

 

[Anthon]

I considered buying a full kit, but I have enough 4x8cm aluminum extrusions laying  around to build 2-3 machines (the same kind used in the Probotix Nebula), so I would save a lot of money if I would build one from scratch.

I do want to buy a 4 axis Nema 23 kit, with all motors, drivers, PSU's etc
Then I would need some supported rails and ballscrews.

 

[gyraf]

With the current prices of ready-built chinese cnc machines, I don't think it's such a good idea to try to re-invent the wheel by designing your own. Designing for stability is not easy and takes more than just buying decent hardware.. Been there, tried that.

Jakob E.

 

[Anthon]

With the current prices of ready-built chinese cnc machines, I don't think it's such a good idea to try to re-invent the wheel by designing your own. Designing for stability is not easy and takes more than just buying decent hardware.. Been there, tried that.

Jakob E.

It's not like I'm designing my own thing... just ripping of an already existing design  ;D

It seems a lot of people who buy these cheap machines, have to mod them for better stability anyway. I haven't seen 'cheap' machines for the applications I'm after.
Even a flimsy bare bones  X-carve 1x1m runs at 1400 euro, which is not suitable for real woodwork, doesn't contain all necessary parts to make it work and is not big enough.
Or maybe I missed something.

Besides, if the effort spent would be a deciding factor, then we all would have to quit DIY.
The way I see it, time is not as issue for DIY projects.

 

[totoxraymond]

I considered buying a full kit, but I have enough 4x8cm aluminum extrusions laying  around to build 2-3 machines (the same kind used in the Probotix Nebula), so I would save a lot of money if I would build one from scratch.

I do want to buy a 4 axis Nema 23 kit, with all motors, drivers, PSU's etc
Then I would need some supported rails and ballscrews.

The nice thing about the open maker machine is you don't have to buy a full kit, they also offer to buy just the custom pieces, or even just the piece that are not generic and/or machinable/printable. (Motors, electronics...) With the plans and everything.

And they have different models for different prices, precision, reliabilty.

Thomas

 

[dirtyhanfri]

My experience:

I've using a small Chinese CNC for two years, then I needed something bigger.

I have a mechanical engineer friend and also a profesional machinist, I managed to seduce both to help me designing and building my machine.

After looking zillions of construction logs, tons of hardware vendor's web, hours of pre design, I decided to spend 1500€ in a bigger chinese machine, stronger and with better spindle than the old one. Bought as a Kit I saved like 500€ for way less than 50 work hours.

One month after it crossed the world, waited for me a few days for me and today did it's first (amazing) run.

If I took the other way today I would spent way more money and have a way less functional machine.

If you're gonna enjoy the time, go for it and build the machine. If you need it for work, buy a made (or semi made like I did) machine.

Just my 2cents.

 

[ruairioflaherty]

After looking zillions of construction logs, tons of hardware vendor's web, hours of pre design, I decided to spend 1500€ in a bigger chinese machine, stronger and with better spindle than the old one. Bought as a Kit I saved like 500€ for way less than 50 work hours.

Which one did you buy?

 

[dirtyhanfri]

A Chinese 6040 with 1,5kw spindle

 

[Anthon]

6040 is 600x400mm...

I really do need at least 4 times bigger (1500x900) - because I want to do small production batches of guitar cabinets,10 cabs simultaneously - currently I do 6 manually.
6040 would fit only 1 or 2 parts of the cabinet at once -  and you need 7 parts for each cab. So 70 parts for a batch of 10.
Loading and pre-cutting the materials each time would be PITA. I could do it faster manually, using templates for my hand router.

With 1500x900 I could fit up to 9 parts (dozens of smaller parts, like rear panels), very little pre-cutting would be needed.

About enjoying the time vs work: it's a bit of both. On one hand I'm interested into building my own CNC, but on the other hand I really need one for work also.  I'm currently in a 'semi-pro state' - so it is still a hobby, but I do earn money with building stuff also.
If I could buy a large and sturdy machine for 1500 euro, I would probably buy it. But a machine with supported rails, ballscrews etc with the size I need would cost me at least 4-5k euro.

 

[Timothytitus88]

Hey Anthon,

A few things to consider...

Firstly, you are talking two machines in one, and that's not really a good idea,  particularly on a DIY budget. The rigidity and precision required for doing the precision aluminium machining and engraving will be very difficult to achieve on a machine with the dimensions you describe. For example, when I am machining a 19" panel, 0.05mm variation in depth of cut can make a difference. That variance would not  even be noticeable when woodworking. A carefully designed and assembled machine can manage those kinds of small dimensions over a travel of (say) 500mm. but 1500mm is another thing altogether.

That said....  I am in the middle of building a new machine that will have a cutting area of 900 x 600mm and I'm hoping it works as nicely as my current machine (oh and note my current machine has a fixed gantry)

Another consideration is mixing the materials on the same machine. For aluminium you will quickly realise that you need cutting lubricants. The machine has to deal with that, and all the muck the goes with it. The last thing you will be wanting to do is mix saw dust with it...

If I was you I would go ahead and build a big machine, but be designing it as a woodworking machine. You will learn a lot from doing that and have a pretty good chance of success because of the slightly relaxed tolerances required for the build (but sure throw some ali on to see how it goes)

Cheers,

Tim

 

[Anthon]

Hey Anthon,

A few things to consider...

Firstly, you are talking two machines in one, and that's not really a good idea,  particularly on a DIY budget. The rigidity and precision required for doing the precision aluminium machining and engraving will be very difficult to achieve on a machine with the dimensions you describe. For example, when I am machining a 19" panel, 0.05mm variation in depth of cut can make a difference. That variance would not  even be noticeable when woodworking. A carefully designed and assembled machine can manage those kinds of small dimensions over a travel of (say) 500mm. but 1500mm is another thing altogether.

That said....  I am in the middle of building a new machine that will have a cutting area of 900 x 600mm and I'm hoping it works as nicely as my current machine (oh and note my current machine has a fixed gantry)

Another consideration is mixing the materials on the same machine. For aluminium you will quickly realise that you need cutting lubricants. The machine has to deal with that, and all the muck the goes with it. The last thing you will be wanting to do is mix saw dust with it...

If I was you I would go ahead and build a big machine, but be designing it as a woodworking machine. You will learn a lot from doing that and have a pretty good chance of success because of the slightly relaxed tolerances required for the build (but sure throw some ali on to see how it goes)

Cheers,

Tim

I thought about it also.
Yes, mixing sawdust and liquids would be terrible.  :

Maybe I could buy a small machine for engravings and aluminum work first, like other people have suggested, and make a DIY machine specifically for woodwork, which doesn't require high precision. Also, I could make custom parts using this small machine for my bigger CNC  ;D
Then I would probably go for rack and pinion, and build a 2600x1500 working surface, because then I could load the materials without any pre-cutting, and make big amount of parts in 1 go.
I have aluminum extrusions up to 3m in length, and I have plenty of them.

6040 would be good for small work.
Any other machines to consider?

Edit: after some thinking, I think I'll go for a big CNC first.
Because a woodworking CNC is what I really need now. A precision CNC for aluminum can wait.

 

[totoxraymond]

Hi,

I just reminded about an interesting project that might fit your needs if you just want wood routing:

http://www.maslowcnc.com

 

[Jarno]

Edit: after some thinking, I think I'll go for a big CNC first.
Because a woodworking CNC is what I really need now. A precision CNC for aluminum can wait.

But, you are thinking of making guitar cabinets, right? You need a good table saw, not a router. They are all straight pieces? It takes a lot longer to do even if it is a CNC machine. Obviously, if it is curved pieces etc, a router will be helpful, but most pieces on a regular guitar cabinet have straight cuts.

 

[grievousangel]

OK, I'm sold!

Where can I buy a affordable CNC XYZ Table Kit suitable engraving 19 to 24" panels? Vacuum hold downs?

Where for a larger, stronger XYZ CNC Table Kit for up to 1/4" aluminum and 2" thick hardwood (Guitars)? How large of a table? Is it practical to consider flipping the aluminum to reduce the OAL of the required table? Hold down technology? Clamps or vacuum?

Approx cost of kit(s)? Manufacturer suggestions? Chinese is good right?

Cheers,

Grievous Angel Production

Billy

 

[metalb00b00]

But, you are thinking of making guitar cabinets, right? You need a good table saw, not a router. They are all straight pieces? It takes a lot longer to do even if it is a CNC machine. Obviously, if it is curved pieces etc, a router will be helpful, but most pieces on a regular guitar cabinet have straight cuts.

You are correct, but repeatedly drilling accurate positioned screw holes and cutting speaker holes is a tedious process. But with a CNC router machine, you only need a template to make multiple exact copies. Cutting speed don't really matter anymore.

 

[benb]

There's a big discussion board with probably people who have used whatever you're thinking of getting at cnczone.com.

 

[john.dever21]

Hi Anthon,
I really don't recommend doing it. DIY with an old-fashioned way of designing it and reinventing it and plus your budget it's too risky. In the end, you might end up throwing tools away. haha. this might help you if you still continue building CNC
http://www.powerjackmotion.com/.

John

 

[Eliani]

I've started building my own CNC machine over three times and although perfectly do-able I ended up failing to do so every single time! I failed not because I'm stupid or have two left hands (sometimes questionable), but because I wanted the best money could buy, and wanting to much all at once!

The easiest way to build a cnc is when you have a cnc and can make parts for it! A lot of first time builder buy a cheap kit and cut parts for their new and improved machine... and probably twice more, until thay have a machine that can do what they need it for!

I ended up buying an expensive BZT PFE 1000px, only 15 years after my first DIY attempt!
Ok, so my accountant told me to invest my hard earned money in something otherwise I would have to pay taxes, and I hate throwing away money! So I bought the machine and two ATI Paragon 2 consoles! (sorry had to throw that in)

- 1150mmx720mm workable surface
- full steel construction
- 4.2A motors
- edingcnc CPU5a controller
- tool length measuring device

and a lot more, but having bought this, included warranty, on site support and the guys phone number just in case I break something and he can mend it!

I've recently added a big vacuum holding setup making this a super-machine, costing me around €7500 not including VAT... yep, way more then I ever thought I would spend on a machine like this. But dude is this great! I've collected over the years so many applications I thought damn... what if I had a CNC machine!

 

[Anthon]

But, you are thinking of making guitar cabinets, right? You need a good table saw, not a router. They are all straight pieces? It takes a lot longer to do even if it is a CNC machine. Obviously, if it is curved pieces etc, a router will be helpful, but most pieces on a regular guitar cabinet have straight cuts.

I have table saw and a router.

This is example of my work, that I currently do with regular tools

This is a Fender 5e3 replica cab. I've made a dozen of them last year.

As you can see, plenty of curves, and other shapes. Also, things have to be precise to 1mm - like mounting holes etc.
It might seem like building a cab is just 4 straight pieces of wood put together, but it's just more complicated than that. There are numerous of tiny things that make fabrication of these cabs a pita, especially if you start making custom ones - for standard cabs, I can at least use templates I made, but for a new cab I have to cut everything by hand, which takes forever.

I've spent half a day of cutting 6 sets of these back panels only. I bet a CNC router could do the same work 10 times faster, with very little of my effort. The same for speaker baffles.

I'm in a process of building a small business, selling audio related stuff - making cabinets is a good start (I can sell empty cabs, kits, finished amps), but CNC machines will be useful for other things as well.