[ryzaa]

Hi,

I am looking for a kit, or plans for a DIY CNC project, however there are many out there and I am wondering what peoples experiences are like for a few of them.
I am also in Australia, so often shipping on kits from OS will kill the price on a lot of parts that I can buy.

Minimum Requirements:
-1200mmx2400mm [4'x8'] X by Y
-150mm of Z travel [6'']

The machine will be used for wood cutting for the most part, with maybe some plexi and aluminium cutting/engraving.

Budget:
I am a student, and on a budget, so ideally I would like to go about it as cheaply as possible. I can get parts machined locally if that helps with the overall cost of things.

-$3000 is the amount that I would like to keep it under.

Other Considerations:
-The ability to add a 4th axis later down the track would be excellent, but isn't necessary. If it were possible to add on later, my z travel would have to be much larger.
I would probably need at least a part of 500mm [5/3'] diameter to be able to fit.
How feasible is this, and will I lose precision by having a larger z travel? How much of an issue will this be?

I know there are a few kits that are made from CNC cut ply board. I am concerned slightly that such designs over time will begin to warp/lose accuracy. Is this a possibility, or should I not worry about it?


Dust extraction and the like is not to come under the budget. Only things directly integrated into the router are to be taken as a part of it [ie stepper motors, spindle, bits, suction area to hold work down, etc]

If there are any other bits of information that people need to know, feel free to ask.

Thanks,

Ryan

[awerby]

Hi,

I am looking for a kit, or plans for a DIY CNC project, however there are many out there and I am wondering what peoples experiences are like for a few of them.
I am also in Australia, so often shipping on kits from OS will kill the price on a lot of parts that I can buy.

Minimum Requirements:
-1200mmx2400mm [4'x8'] X by Y
-150mm of Z travel [6'']

The machine will be used for wood cutting for the most part, with maybe some plexi and aluminium cutting/engraving.

[Have you looked at the Mechmate plans? MechMate CNC Router - Build your own with our detailed plans That seems like a sturdier machine than most, although I'm not sure it has that much Z travel.]

Budget:
I am a student, and on a budget, so ideally I would like to go about it as cheaply as possible. I can get parts machined locally if that helps with the overall cost of things.

[It's hard to see how it would; custom machining is not usually cheap, unless you've got a machinist pal who works for beer.]

-$3000 is the amount that I would like to keep it under.

[That's going to be difficult, especially if you're buying a kit. Your best bet might to start scrounging around for used machines to cannibalize, and work out a plan around what you manage to find.]

Other Considerations:
-The ability to add a 4th axis later down the track would be excellent, but isn't necessary. If it were possible to add on later, my z travel would have to be much larger.
I would probably need at least a part of 500mm [5/3'] diameter to be able to fit.
How feasible is this, and will I lose precision by having a larger z travel? How much of an issue will this be?

[Adding length to your Z axis will decrease the rigidity of your machine, all things being equal. But if you go with a sunken rotary axis, where the center of the A axis is at the height of your bed, then you can add it without raising Z. That's part of the advantage to designing a machine yourself - you can accommodate things like this.]

I know there are a few kits that are made from CNC cut ply board. I am concerned slightly that such designs over time will begin to warp/lose accuracy. Is this a possibility, or should I not worry about it?

[Yes, it is a possibility. A metal structure would be better; plywood designs are just easier for most people to build. If you are going to use plywood, use a good grade of it, like the kind used for marine applications (lots of layers, no voids). Think in terms of torsion boxes, rather than depending on single sheets for stiffness.]


Dust extraction and the like is not to come under the budget. Only things directly integrated into the router are to be taken as a part of it [ie stepper motors, spindle, bits, suction area to hold work down, etc]

[You'd be doing well to just get the router done within your budget. Things like tooling and vacuum hold-downs are extra costs to deal with after it's complete.]


Ryan

Andrew Werby
www.computersculpture.com

[ryzaa]

[Have you looked at the Mechmate plans? MechMate CNC Router - Build your own with our detailed plans That seems like a sturdier machine than most, although I'm not sure it has that much Z travel.]

I have had a look at the Mechmate plans. It is hard to gauge what it would cost to build from a plan though. I am looking to see what people have built and how much it has cost them, and how they find their kit.

[It's hard to see how it would; custom machining is not usually cheap, unless you've got a machinist pal who works for beer.]

I have a friend with a CNC machine who makes kitchens who does jobs for me pretty cheaply. But obviously he only cuts wood on that.
I also have another friend who has helped with some bits and pieces in the past who owns a steel pressing plant. Cutting plate, buying metals, etc would be done through him. So there are a few options there in the way of custom work on the cheap.

[That's going to be difficult, especially if you're buying a kit. Your best bet might to start scrounging around for used machines to cannibalize, and work out a plan around what you manage to find.]

I forgot to mention that I already have a box of 50 or so assorted stepper motors, so that won't be an issue. Mostly from industrial printers and the like, but there are plenty of the common motors that I see offered in various kits.

[Adding length to your Z axis will decrease the rigidity of your machine, all things being equal. But if you go with a sunken rotary axis, where the center of the A axis is at the height of your bed, then you can add it without raising Z. That's part of the advantage to designing a machine yourself - you can accommodate things like this.]

How would I go about designing something like this? I have had a bit of a search, but cannot find anything that explains this.

[Yes, it is a possibility. A metal structure would be better; plywood designs are just easier for most people to build. If you are going to use plywood, use a good grade of it, like the kind used for marine applications (lots of layers, no voids). Think in terms of torsion boxes, rather than depending on single sheets for stiffness.]

I also have a friend who runs the local hardware store, so marine ply would be cheaper than for the average person for me. Cheapest Marine grade around here is about $130 a sheet normally. If I did build it up out of wood, should I build all of my parts like torsion boxes?

[You'd be doing well to just get the router done within your budget. Things like tooling and vacuum hold-downs are extra costs to deal with after it's complete.]

Like I said, there are a lot of parts that I already have, so hopefully that will aid me. Computer and stepper motors I already have. I also have a dremel, but I would prefer to not base my machine on that, as I don't think it would be ideal for a cutting machine.

Thanks Andrew,

Ryan

[awerby]

It sounds like you're off to a good start, what with all those stepper motors and useful friends. The thing I like most about the Mechmate design is that the gantry rides on sturdy walls attached to the table, not on wobbly supports that it has to drag around. Lowering the rotary axis center to the height of the bed is pretty simple; just leave a big gap for now (you can bridge it with a removable panel), along with a way to attach the 4th axis assembly underneath. You'll need to fabricate a substructure at some point that will hold the rotary table and tailstock, and allows the tailstock to slide back and forth to accommodate stock of different lengths.

Yes, use torsion boxes whenever possible. They're a lot stiffer than individual sheets. And keep the Dremel for occasional light hand work; it's pretty useless as a CNC spindle. A wood router, while not ideal, will work a lot better.

Andrew Werby
www.computersculpture.com

[pippin88]

There are a couple of Australian sellers of stepper drivers and steppers

Homanndesigns.com
Ausxmods.com.au

500mm is absolutely massive z travel and will be bloody difficult to achieve while napping a decent machine

[ryzaa]

Hi,

Sorry I was never notified of a response.
Thanks for those links, I shall investigate them further when I decide on what I want to build. A friend and I are pooling resources on one now, so the budget may be able to stretch a tad more.

500mm of Z travel is not a necessity. The machine will mainly be used for straight through wood sheet cutting, with the largest pieces being about 150mm high.
I have another place that does my current 4 axis stuff for a pretty reasonable price. It would just be nice to be able to prototype a bit more by having my own, however I can continue what I am doing, and try and save some money by doing the odd job here and there on my own.

Andrew,
I like your idea of an adjustable work height, as obviously the Z travel will be most accurate up closer to the top. I may try and incorporate such a design into whatever it is I end up deciding on.

I haven't had much chance of late to look at any kits, end of semester assignments, and now exams and exam study have taken up too much of my already limited spare time unfortunately.

Thanks,

Ryan

[ger21]

It would be virtually impossible to build a 4x8 machine for $3000 in the US. From what I understand, it would cost considerably more in Australia.

There are many Australian members at the Mechmate forum. I'd ask them what it costs to get one up and running. Probably $5000-$7000.

A CNC Routerparts Kit is probably the closest thing to what your looking for, but again. it's over your budget, and shipping will add considerably more to the cost.

A few other things.

A dremel is insufficient for even the smallest machines. Plan on spending at least $500-$700 for a suitable spindle for a 4x8 machine.

It's unlikely that stepper motors from printers will be adequate.

Bottom line, is that I think you have unrealistic expectations for your budget.

Even building a machine from wood will exceed your budget. More importantly, you won't find any plans for a 4x8 wooden built machine. I've seen several attempts over the years, but no complete running machines that size. Here's the closest that I've seen. Brian Oltrogge | Grünblau Design Studio | MDF3790