Anthon

Considerations for building a CNC.
« on: September 01, 2017, 06:55:59 PM »
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

Re: Considerations for building a CNC.
« Reply #1 on: September 03, 2017, 02:17:31 AM »
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

Re: Considerations for building a CNC.
« Reply #2 on: September 03, 2017, 07:22:46 AM »
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

Re: Considerations for building a CNC.
« Reply #3 on: September 03, 2017, 09:40:16 AM »
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.
..note to self: don't let Harman run your company..

Anthon

Re: Considerations for building a CNC.
« Reply #4 on: September 03, 2017, 10:13:02 AM »
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.
« Last Edit: September 03, 2017, 02:30:01 PM by Anthon »

totoxraymond

Re: Considerations for building a CNC.
« Reply #5 on: September 03, 2017, 04:04:33 PM »
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

Re: Considerations for building a CNC.
« Reply #6 on: September 03, 2017, 06:00:11 PM »
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.
Working on it...

ruairioflaherty

Re: Considerations for building a CNC.
« Reply #7 on: September 03, 2017, 08:31:57 PM »
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

Re: Considerations for building a CNC.
« Reply #8 on: September 04, 2017, 02:14:37 AM »
A Chinese 6040 with 1,5kw spindle
Working on it...

Anthon

Re: Considerations for building a CNC.
« Reply #9 on: September 04, 2017, 06:39:15 AM »
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.
« Last Edit: September 04, 2017, 07:40:59 PM by Anthon »


Timothytitus88

Re: Considerations for building a CNC.
« Reply #10 on: September 04, 2017, 09:32:10 AM »

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

Re: Considerations for building a CNC.
« Reply #11 on: September 04, 2017, 04:58:47 PM »
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.

« Last Edit: September 04, 2017, 08:19:13 PM by Anthon »

totoxraymond

Re: Considerations for building a CNC.
« Reply #12 on: September 07, 2017, 06:54:07 AM »
Hi,

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

http://www.maslowcnc.com

Jarno

Re: Considerations for building a CNC.
« Reply #13 on: September 22, 2017, 07:24:25 AM »
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.