$5000 machine build, need suggestions

Printable View

03-01-2014, 08:08 AM
cncmadness

$5000 machine build, need suggestions

I am looking at building myself a cnc machine and I have set a budget of about $5000. This will be my second build as I have already built a modified Momus machine. The reason I am wanting to upgrade to a new machine is that I have found that I have reached the limit of the machine and in order to be more productive I need faster feed rates or to be able to make deeper passes, which is not possible on the machine that I have. So I have been thinking a bit about the next build but would like to get some suggestion and input on which direction I should be going. For the machine I will be cutting lots of fiberglass sheet and aluminum. I am able to do the job now but it is slow.

So here is an idea of what I am thinking. Build my own frame or buy the 48"x48" kit from cncrouterparts. If I buy the kit, it would be easier to build but will I get as much out of the machine as I would by building my own.

Frame
Home built or purchase - I have built my last machine frame and am able to build the next but I have been wondering if it is worth it or just better to buy a frame.

Rails
Have considered two option. V-bearing or LINEAR MOTION RAIL GUIDES from THK - If I bought the kit it comes with the v-bearing, but if I build my own frame I could choose. Which will be better for what I am trying to do.

Motion
Rack & pinion or ball screw - I have read that the ball screw is slower but holds better and has zero backlash. Speed is not a big issue as is accuracy. The jobs that I am doing are small, just right now I am having to do 4-8 passes to complete the cut where as with a better machine I hope to do it in 2 - 3 passes which would speed everything up.

Z axis
Even if I build my own frame I have considered buying a z-axis that is already built and ready to go. I want something that will be up the task. So even if I build my own frame I was considering getting the z-axis from cncrouterparts. Will this z-axis be up to the job or is there another source in which I could get one that would work better.

As I said I have set a budget and that budget is what I need to buy the complete kit from cncrouterpart. But then I wonder if I would get more for my money if I build my own. Any suggestion on whether I buy or build would be great. And if I build which option should I consider to get the most for my money.

Thanks in advance for any help you can provide.
03-01-2014, 02:53 PM
ger21

If you have the equipment and skill to do it yourself, than the DIY route will definitely get you more for your money, provided you consider your time to be free, as you'll spend a lot more time.

THK rails are a huge step up in rigidity to V Rollers. But that comes at a huge cost increase, unless you find deals on Ebay. There are other brands that are quite a bit cheaper than THK, especially the chinese brands.

I'd probably go with Chinese 2525 ballscrews. Plenty of speed.
03-03-2014, 02:53 PM
wizard

Quote:

Originally Posted by cncmadness

I am looking at building myself a cnc machine and I have set a budget of about $5000. This will be my second build as I have already built a modified Momus machine. The reason I am wanting to upgrade to a new machine is that I have found that I have reached the limit of the machine and in order to be more productive I need faster feed rates or to be able to make deeper passes, which is not possible on the machine that I have. So I have been thinking a bit about the next build but would like to get some suggestion and input on which direction I should be going. For the machine I will be cutting lots of fiberglass sheet and aluminum. I am able to do the job now but it is slow.

This description tells me you need a far more ridge machine.

Quote:

So here is an idea of what I am thinking. Build my own frame or buy the 48"x48" kit from cncrouterparts. If I buy the kit, it would be easier to build but will I get as much out of the machine as I would by building my own.

Kits are nice but would you get a significantly better machine?

Quote:

Frame
Home built or purchase - I have built my last machine frame and am able to build the next but I have been wondering if it is worth it or just better to buy a frame.

That is really up to you. A well built frame won't be cheap though.

Quote:

Rails
Have considered two option. V-bearing or LINEAR MOTION RAIL GUIDES from THK - If I bought the kit it comes with the v-bearing, but if I build my own frame I could choose. Which will be better for what I am trying to do.

Linear profile rails would be a requirement in my mind to take you to the next level.

Quote:

Motion
Rack & pinion or ball screw - I have read that the ball screw is slower but holds better and has zero backlash. Speed is not a big issue as is accuracy. The jobs that I am doing are small, just right now I am having to do 4-8 passes to complete the cut where as with a better machine I hope to do it in 2 - 3 passes which would speed everything up.

The machine sizes you are looking at would be fine with ball screws.

Quote:

Z axis
Even if I build my own frame I have considered buying a z-axis that is already built and ready to go. I want something that will be up the task. So even if I build my own frame I was considering getting the z-axis from cncrouterparts. Will this z-axis be up to the job or is there another source in which I could get one that would work better.

Truly good engineered slides are no cheap at all.

Quote:

As I said I have set a budget and that budget is what I need to buy the complete kit from cncrouterpart. But then I wonder if I would get more for my money if I build my own. Any suggestion on whether I buy or build would be great. And if I build which option should I consider to get the most for my money.

An inventory of time and equipment would help with decision making here. If you don't have the time then the cost of kits isn't as big of a deal. As for equipment if you don't have the shop tools to do the job it can be very difficult to do a good build. Where you come up short equipment wise you can always find a machine shop but that does add to the cost. In the end only you can decide if buying or building is right.

Quote:

Thanks in advance for any help you can provide.

I suspect that you aren't thinking of a substantial upgrade that would be a worthwhile upgrade to your current machine. There are a couple of really good threads that go into building a properly stiff gantry beam, which I'd suggest reading before making any decisions. As such a significant upgrade to your current machine will likely involve a machine with a bigger beam than you are currently imagining.
03-03-2014, 07:19 PM
cncmadness

1 Attachment(s)

Thanks for the reply’s,

I do understand that this machine will be bigger and will require a bigger gantry. I have attached a picture of my first machine. As I have built it myself, I know that these things take time but for me that is half the fun. So I don't mind if my time is free. Here is a link of the machine at work. Its slow but does the job. I am now looking for faster. As mentioned my goal is to cut aluminum and I also cut a lot if fiberglass sheet.
Cutting an Anti Rotation - YouTube

Prototype Panzer A4 Quadcopter frame - YouTube

Some things that I have noticed and would like to upgrade with the current machine.

Bigger table - I was thinking of making it 48"x48" rather than the current 24"x24"

Movement - At the moment I am using belts and I can notice that by grabbing the gantry that I can move it and that it is nowhere stiff enough for the job. I have also seen this in some of the parts that I have cut. I have been slowed to about 3-4mm/sec and 1mm depth.

Movement #2 - I have noticed that a bunch of machines use a single motor on the y-axis which is placed under the table and connects to risers. Is this a better design? At the moment I like the frame that I have and was thinking of improving on it for the next frame. I like that the risers are built into the machine and that it simplifies it by not having the risers. I also believe this would make it stronger as my risers are 1.5x3 inch steel beams compared to having thinner aluminum or steel risers on the sides that move with the machine. Plus there is less material that the machine has to move around.

Movement #3 = On my current machine I am running 2 motors on the y-axis. I like this design but is it necessary. I have also found that over time the one side moves more/less than the other and I have to re-adjust to make it square again. Is there another option or am I best to keep the two motor.

I'm sure that I have decided to build my own machine rather then buy the kit. I have decided to go with the linear profile rails as suggested they would be a requirement for my goals and that they would be better then using the v-bearing. At the moment I am looking at upgrading the frame that I have to be bigger. The thought is to mount the rails right to the top of the frame and mount the y-axis from there.

As I have said I am open to options or change of thought on the ideas that I have mentioned. Please correct me if I am wrong and point me in the right direction.

Thanks