[Zygoat]

Hay guys!

this is my first post over here. i am in the early research stages, planning to build my own cnc. i am pretty excited about it. this is something i have always wanted to do. i am looking for all the help and knowledge i can get.

a little about me. i have some precision machining experience. (strong arm mill, lathe, turret lathe.) as well as some cad experience. i have been working with tools and computers all my life (i build computers as a hobby). i have been a tradesman for about a decade now. going to school for engineering. i am a certified electronic technician.


here is the basic plan i have cobbled together so far.

i was looking at a gantry type system. ( i am wondering why the metal working guys use more of a moving bed system?)

i originally was planning on building the structure using extrusions from 80/20. but the cost seems a little prohibitive. i have found some surplus stuff on e bay, and that may help bring the cost down a little. i would still REALLY like to build it this way, so if anybody has any other sources for parts or a place where i can get this kind of stuff cheap; please let me know.

here was the original design for the bed frame.



after i decided that the cost was probably too high for me with the 80/20 stuff. i re designed the cnc using mdf as the main structure.



keep in mind this is still a very early rough design.

the top layer of the bed is semi-transparent so that you can see the torsion box design inside. this is to keep the bed flat and sturdy.



the idea

another important aspect to me was the ability to have a relatively small foot print. i dont have a ton of left over room in my shop. but i also want to be able to attach an extension to the front of the machine and then be able to handle standard 4'X8' sheets. the table is wide enough to take a 4' sheet. but is only 2' deep in its normal state. but i should be able to design a extra bed that could bolt up to the machine that will extend it to the full 8' length. i know getting everything to be completely flat and level will be a challenge here. but i think with "screw type" adjustable feet for the extension it should be possible to make very fine adjustments. also i am considering the use of a probe to be placed in the collet to then measure the z axis all along the table and make adjustments accordingly.

my idea here is to use a chain drive for the (x?) axis. ( the long one). this way i can simply install a longer chain once the long bed is attached and be ready to go.

also even on the short bed, ball screws that have about a 20" of travel for the x and 48" of travel for the y are pretty expensive. so hopefully the chain drive will keep costs down. i do plan on using a ball screw for the z axis, but probably chain drives on the x and y.



what i want to do

i want to be able to make lots of one of parts. or maybe some very limited production runs. (10-20 parts.)

i do however want to work with a lot of different materials.

wood
plastic
foam
aluminum
maybe steel.


from what i understand i should be able to do the above, with the understanding that i will have to work the metals much slower, particularly the steel. i have no problem with that. if on the rare occasion i need to cut something out of steel and it takes me 20hrs. to cut then thats just how long it takes.

the remaining problems so far are as follows.

i am not entirely sure how i want to set up the track system. i have seen a lot of work with aluminum and steel angle. the seems like the route i want to go. anybody have links to a system they have seen that works well?

lastly i would like to be able to use coolant for when i am cutting metal. (this would be possible with the 80/20 structure.) if there are any other options that could accommodate this please let me know.


lastly cost is the major factor here. i would like to get the basic machine up and running for around $500. i can build everything my self, the computer side of thing is no problem. the electronics for the controllers i will probably have to buy. ( i could, and have built similar things, but the ready made ones, or the kits are about the same cost a building them from scratch.) also i am patient, so i have no problem waiting until i can find the parts i need for a steel of a price.


if you read all that THANK YOU! please let me know your thoughts, any help is good help.


Justin.

[DIYaholic]

Welcome Zygoat,

You have asked alot of questions. As a newbie myself ,there is no way I can answer all/any of them, (with any real level of expertise).
From what I understand, the moving table design lends itself to a more ridgid machine increasing cutting accuracy and surface finish quality when machining steel.
With an MDF bed structure, it will be a little tough to do any flood/wet cutting of steel. IMHO dry cutting or light mist lubrication may be possible for soft metals (aluminium, brass), steel could be iffy.
You can "index" large and full sheet goods (MDF, ply) and cut them with a table extension. (you would need to move the peice as sections are cut)
"Track System" will need to be steel or better (supported rails, linear slides) if you want to cut aluminium and steel with any accuracy. There are many DIY designs out there, also CNCRouterparts has premade bearing carriages that many use very effectively.

Hope I have been of some help. But as a newbie, my knowledge and experience is limited.:withstupi I'm sure the true "experts" here on the zone, will chime in and offer much better advice. Good luck with your research and future build. Remember to post lots of pictures of your build.:cheers:

Randy,

[Zygoat]

thanks. i did not go into full detail on everything. as i did not want to write a book.

if/ when i want to cut metal. i will either have a swappable bed or a fixture that will allow me to contain the fluid and metal shavings/chips.

i like the idea of changing the whole bed out the best.

for example if it built the frame out of the 80/20 extrusions i could then mount the mdf bed most of the time and have another bed built and swap that on to the frame for metal cutting.


thats my idea anyway.


couple more notes.

i plan on using stepper motors.

just a note about me. (so you guys can help recommend stuff for me.)

for me its all about marginal benefit. for example if part x is not as good as part y and part y is only $20 more, or maybe 10-15% more, then i will usually go with the better of the 2. also i am pretty good at knowing where money needs to be spent. for example the ball screws instead of normal threaded rods, but also where money can be saved. the router mount could be made of mdf or other in expensive material, as long as its well designed all it had to do is hold it in place.

[DIYaholic]

I think I know where you are coming from. I too, am in the research & design stage. I won't have a shop to build in (or put a machine in) until at least spring.:violin: Until then, I'm researching and designing my future build.
I like your idea of switching out the torsion box bed for the flood cutting bed (an idea I'm also considering). My design will incorporate a lot of stolen ideas.:devious: Heck, I don't know if I truely ever had an original idea.
I'm looking at designing/building a 3' X-axis X 4' Y-axis machine. I plan to use Rack & pinion for X and Y travel, this way I can either temorarily extend the 3' table and "index" large/sheet goods, or (when I have more room & money) permanently lengthen the table to 8' and reuse the Y-axis gantry. I am also considering a bed that raises and lowers so as to keep the z-axis travel as small/compact (hence more rigid) as possible. This will allow me to work larger pieces without loosing rigidity/accuracy. To make the initial build affordable, I will use 8020 extrusion for the Y gantry and MDF for the gantry uprights. I will upgrade the uprights to 1/2" aluminium plate when funds become available (I'll have the machine cut it's own upgrades).

You have come to the right/best place to research your build. The "experts" here at the Zone are eager to share their knowledge and help us newbies succeed.

Happy reading/researching.:cheers:

[YZF]

Hi Zygoat,

What's your budget? Do you have access to a machine shop?

I'm far from an expert on machining but as I understand it you'll need a very stiff machine to do any cutting of steel. There's only so far you can go trying to take lighter and lighter cuts, at some point the tool will just bounce of the surface of the metal and if/when it does cut it will chatter/go in and out of the workpiece.

If you're on a tight budget e-bay and patience are your two friends :-) Cast a wide net and then base your build on what you fish... Just don't steal the parts I need ;-)

[Jesse B]

I'm far from an expert on machining but as I understand it you'll need a very stiff machine to do any cutting of steel.

Yeah, to cut steel you'll need a very, very rigid machine. Even milling Aluminum requires an extensive amount of rigidity. You'll need to take fairly shallow passes as well.


- Jesse

[Zygoat]

alright thanks for the input guys.

i know i am pushing the limits of whats possible with so little money and what i want to achieve, but i think with a solid well thought out design it should be possible.

also i mentioned it in my first post but if you didnt read it i dont blame you. looking to spend around the $500 mark. like i said, the computer end of things is not a problem. and ill build it all my self.

still looking to learn so feel free to post.

[Jesse B]

alright thanks for the input guys.

i know i am pushing the limits of whats possible with so little money and what i want to achieve, but i think with a solid well thought out design it should be possible.

also i mentioned it in my first post but if you didnt read it i dont blame you. looking to spend around the $500 mark. like i said, the computer end of things is not a problem. and ill build it all my self.

still looking to learn so feel free to post.

Is that $500 including the electronics, or just the mechanical portion of the build?

(By electronics I mean Motors, Drivers, Power Supply, etc.)

[stangtjk]

I've just started collecting parts for my router build and I'm really doubtful that you'll be able to pull off a build that you'll be proud of for what you want to spend, especially at the size you're considering and for it to be able to mill aluminum or steel.

I know you can pick up some killer deals off ebay but even so it'll be hard to stretch that $500.

I'm not trying to discourage you, you may luck into better deals than I have but if you look at the list of parts you need you may rethink your budget.

PC
drivers
power supply
motors
linear bearings of some sort
the drive mechanism
materials for the machine itself
misc. wiring and hardware
shipping costs
etc...

I'm trying to build my machine on a tight budget as well but I've probably spent $100 or more just in shipping costs for the stuff I've purchased from ebay.

[YZF]

alright thanks for the input guys.

i know i am pushing the limits of whats possible with so little money and what i want to achieve, but i think with a solid well thought out design it should be possible.

also i mentioned it in my first post but if you didnt read it i dont blame you. looking to spend around the $500 mark. like i said, the computer end of things is not a problem. and ill build it all my self.

still looking to learn so feel free to post.

Oops. Missed your $500 number. Do you have access to a mill?

You'll need to be creative and minimize your spending on the different components. E.g. just looking on e-bay right now I see someone selling an IM483 stepper driver for $25 (used). You'd need 3. If you'd buy that new it's probably >$300 each. Now you'd need to hunt for a used stepper motor to go with that. Just a quick look found me a NEMA34 stepper motor that seems out of favor with buyers but may work great. You'll need to see what you can get out of a motor given the 48V/3A limit. Let's theorize you can get that for less than $10. Now you've steppers + drivers for about ~$100. If you're patient you can over time pick up used screws and linear rails (maybe buy rails and blocks separately) for very decent prices. Odd bits of various aluminum extrusions come up as well. Sometimes you can find a complete axis/stage with motor, screw and rails. Now it's not going to be a kit or anything and you'll probably need to get creative and make some of your own parts to put everything together but I think it can be done, i.e. a good machine for this budget. So the theme is buy used stuff that is more difficult to work with/"non standard" and you can get a lower price and end up with pretty decent performance if you can and are willing to do more work.

Just some thoughts...

[stangtjk]

YZF, I agree with a lot of what you said. Its pretty much exactly what I've done for the past 2 months collecting parts.
I picked up 4 IM483H and 3 IM805H drives for around $40 each after shipping, power supply was another $30.
My z axis is a used IAI linear actuator I snagged for about $30 after shipping. Spent about $150 on all the linear rails and another $140 on belts and pulleys to drive the X and Y.
$50 for a lot of 4 stepper motors.

There's more but that already ads up to $490 if you neglect the 4 extra drives I purchased.

I think I've found some pretty damn good deals myself and I'm already over that $500 mark so I'm a little skeptical.

[YZF]

Yeah - fair enough. Also the larger the machine the more difficult it becomes.
I'd prefer a screw drive to belt or chain myself. Just out of curiosity what sort of belt are you going to be using?

[Zygoat]

Oops. Missed your $500 number. Do you have access to a mill?

You'll need to be creative and minimize your spending on the different components. ...you'll probably need to get creative and make some of your own parts to put everything together but I think it can be done, i.e. a good machine for this budget. So the theme is buy used stuff that is more difficult to work with/"non standard" and you can get a lower price and end up with pretty decent performance if you can and are willing to do more work.

Just some thoughts...

exactly my thoughts. i have no problem waiting until a good deal comes up. (for an example) i am turbo charging my truck. (would have been nice to have a cnc!) and i spent over a year on research alone. i saved $$$ building a lot of the parts myself.

also like i said, i build computers. i dont know how much you guys know about them, but my current system is

amd phenom ll X4 965 (black edition)
8 GB of ram
2 TB of hard drive (in a raid 0 array)

i built that for around the $500 mark. not including the p/s optical drives and graphics card. (i had some that were still great. still better than the stuff that would come in a pre-built box).

if you priced out that system it would be at least around the $2k mark.

just giving an example.


do i have access to a mill.... kind of, i can use the stuff at school. i might have access to the cnc plasma cutter over the summer.

YZF, I agree with a lot of what you said. Its pretty much exactly what I've done for the past 2 months collecting parts.

There's more but that already ads up to $490 if you neglect the 4 extra drives I purchased.

I think I've found some pretty damn good deals myself and I'm already over that $500 mark so I'm a little skeptical.

i completely understand. it may end up being more. but for now at least that is my goal. i may be way off target since i am new to this, and dont know completely what everything costs. but i do have a habit of making thing for amounts of money people say is not possible.



i would love to see any threads, or information on what parts any of you guys would recommend for the motors, drivers ect.


i was looking at these


#23-305-DS8A (425oz-in bipolar rating, 305oz-unipolar rating) whatever bipolar is.
http://www.hobbycnc.com/products/stepper-motors/

let me know if they are junk or not.

[Zygoat]

i figured i should show you guys some of my work.

here is a clock i made in one of my machining classes.





i cut this base out of aluminum stock, using only a band saw and a ruler to within +.020" ( and i wanted it big, so i could finish it, read below).

i dont like to brag, and i dont think im the best machinist ever (or even really that good.) but i do think it is important, especially since i am new here, to show you guys that i can build good products, accurately using simple tools. i am 100% sure i could have achieved the same with a hack saw and a square. (tho admittedly less fun.)

the piece below was subsequently finished using a disk sander for the first rough sanding, and from there on COMPLETELY by hand, sanding up to 2000 grit, and then 3 stages of polishing compound. result was 8.000" ( and i got an A)




i think it came out pretty good, and just trying to let you guys know what i can build by "hand". and showing that with patience, it is possible to build precision pieces with nothing but simple tools.


plus i know you guys love to see shiny metal!

[stangtjk]

Yeah - fair enough. Also the larger the machine the more difficult it becomes.
I'd prefer a screw drive to belt or chain myself. Just out of curiosity what sort of belt are you going to be using?

It really came down to price for me, I found that I could do the belts cheaper than lead screws. I found some good deals on all the pulleys and belts I needed so that's what I went with. The belts are 3/4" wide L pitch. I don't want to hijack so here is my thread if you want to look or have questions.

I think using belts is probably a better option than chain however.

Zygoat, I know all about doing things for cheap when others say its not possible. I was told I couldn't drop in a 4.6 DOHC into my 68 mustang for cheap because most of the guys doing the modular conversions spent $10k or more on similar builds. I've only spent around $1K on the whole build not just the motor swap.


Those motors are probably fine, I've seen a lot of other builds on here using them but from what I've read the #23-205-DS8A may be a better choice because they spin faster. Really depends on the weight of your gantry and how fast you want your machine to go. I'd probably get your basic design worked out before picking out your electronics so you can be sure to get what you need.

[Zygoat]

well i did some more work on the overall design.

spent quite a bit of time on the torsion box. making everything lighter. i reduced the number of cross-braces significantly. the first one was just quick. this one is more like it will be built. i removed material inside the braces themselves to help reduce weight further. i also switched to 1/2" mdf instead of 3/4". also to save weight. i have designs in mind to strengthen the structure up. and plan on running stress simulations to verify my design before i build it.

result. 25lbs of weight saving.

it now weighs appox. 75 lbs. as pictured

[stangtjk]

This is going to be a moving gantry correct? If so is the weight of the table that much of a concern? I wouldn't want to have to cut out all of those pockets if it wasn't necessary.

[DIYaholic]

Zygoat,
I have to agree with stangtjk, reducing the weight of the base table is of less importance, unless you want it to be more portable. I may be wrong (someone correct me if I am :withstupi), but more mass in the base table may help to absorb vibrations, yeilding cleaner cuts. Also, you want the base table as rigid as possible, to decrease deflection from cutting forces.
Are you planning on doing a torsion box for the gantry? The gantry is where you may want to consider decreasing weight.
Just wanted to chime in with my $0.02 worth.
BTW, excellent work on the clock. YES, shiny metal is good!!! Obviously you are talented and very capable of building a quality machine.

Randy,

[Zygoat]

i think both of you are right. i was thinking about the gantry system, when i decided to save as much weight as i could. then i went a little crazy and applied it to the bed as well. i probably will pass on the pockets in the bed. they will be present in the gantry. thanks for keeping me honest.


i went on a little information gathering trip today, to the local home improvement store. just to price things out and get a feel for what i want to do.

maybe ill be able to get started on the bed sometime soon. we will see.

[DIYaholic]

Zygoat,
Don't forget to add sealer and/or paint to your budget and shopping list. Moisture/humidity & MDF don't play well together. I'm not sure what folks have used to seal their MDF machines, so I would search around the Zone to find out. IMHO the earlier you seal it the better.
FYI: I have also read where the use of "super glue" helps to reinforce bolt holes/threads.

Randy,