Help Requested : New to CNC, need advice on Aluminum

X-Carve
1

Hey everyone,

Thanks ahead of time for taking a look at this. I’ve been browsing forums and looking at devices, but I don’t have a background in CNC. I’m a little familiar with CAD software, but that’s about it. I’m a programmer by trade, so I actually feel like the software side of things will be the easiest for me. I’m a hobby woodworker at home, so I have some familiarity with terminology, but not much machinist experience. Cutting to the chase, I have an idea for a product I’d like to market.
To create this product, I need to be able to create 72+ holes in aluminum (preferably), and they need to be at least 1/2-3/4" deep at about 10mm diameter (I know I just committed a crime by shifting from imperial to metric in one sentence, don’t kill me!). The tolerance on this project would be much aided by CNC. So I’ve been looking at CNC kits. From what I can tell, the x-carve, Shapeko, and similar products are not very well suited for aluminum, especially at the depth I’d like to cut. It doesn’t seem impossible, but even if I managed to rig up something that could do it, it seems that it’d be very slow with the spindle tool sizes allowable. By browsing these forums, I see some more expensive tools like the Tormach solutions that look like they could easily do what I need, but are a bit on the expensive side and ramp up the risk of my endeavor significantly.

Is what I’ve said here accurate? Are there any people out there with experience in this area that can make recommendations? I’d really appreciate any help I can get.

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I started working in my fathers machine shop in 1964 and became a CNC programmer in 1981. All my work has been high tolerance aerospace parts. Since you want to manufacture a product and don’t have the know how I suggest one of two things.

  1. Draw up your product in a cad program with dimensions and tolerances and request bids from local machine shops. Ask for bids on increasing quantities. i.e. 5, 10, 25, 100 and 1000 the bigger the order the cheaper the per-piece price.

2 Try it yourself on a prototype. 72 10mm holes at .5 to .75 depth is easier done by hand. get a center drill to spot the location on the cnc and finish up on a drill press. use an undersized drill to the proper depth and open up the hole with an endmill or flatbottom drill to make the bottom flat if needed. this is not needed for thru holes.

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First of all, thanks for the advice!

The first suggestion is likely a very wise one, I’m just the stubborn type that has to try my hand at automation before offloading it to a third party.

I’ve built a prototype out of wood by hand with a drill press using carbon paper copied over from a sketchup blueprint. It works, but I feel the QA would be a nightmare. I was hoping that a CNC would be more accurate! I could always build it in two pieces with a through-hole and a plate added to the bottom afterwards, but one piece would be most desirable. You really think a work-flow of cutting 72 holes would be faster by hand? In countless pieces? Ouch!

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it depends on the machine used. if you have to adjust the machine every third part yes, a drill press would be faster.

You did not say how big the material is so I don’t even know if it would fit on a drill press. Drilling requires less force than milling. spot drilling on the cnc will give better location accuracy. If the x-carve had a peck drilling cycle you might be better off. Milling holes produces lateral forces that can cause the aforementioned adjustments to be required more frequently.

If your going for “countless pieces” definitely get a quote from local shops. they are set up to do this kind of work very quickly and will more than likely save you more time for marketing your product and lots of money to boot.

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In my prototype the material extends just past the holes, so they are barely not through-holes. I want to prototype a couple of depths and material thicknesses just to get an idea of what would work the best.

“Countless pieces” would eventually depend on demand. Best case scenario would call for hundreds/thousands of units. I wouldn’t mind dropping 2-3k for a CNC to have for the first couple dozen units/prototypes, and then have as a toy for other projects. I’ve always wanted a CNC, and this seemed like an excuse to get into it. I could just never justify the cost! I will definitely look at what’s available from local shops though, as it would be foolish not to. Thank you.

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I think this is the best advice given. Doing yourself is not always the best option. A CNC at your mentioned price point is hardly a production machine

Right, I can see your point. My question is whether or not I could spit out prototypes and the first run of units effectively with a CNC in this price range. If so, does anyone have advice on the best setup/spindle, or would I really have to jump up to the 7k range to get it done effectively?

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he’s talking about 10mm holes (.393 in.) in aluminum.

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for the price of an industrial grade CNC mill he could pay to have 5,000 parts made. At 6in a minute a1/2" thru hole takes 5 seconds or 72 holes in 6 minutes. at a shop rate of $100/hr it figures out to about $10 a part.

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For the right person, buying or financing an industrial grade machine is a better option. My dad left $1.5 million to 5 kids after many years of a good living. He only had 1 cnc lathe and 1 cnc mill and a few manual machines. If I were a young man again and had a product that would sell many thousand parts I would have another CNC machine shop.

15

This kind of question comes up a lot and the answer is tricky, because there are a lot of variables to balance.
I love my XC, use it regularly and am constantly modifying and upgrading it. So much so that very little of the original machine remains.

As an introduction to CNC I think the XC is a excellent choice. It has good customer support with an active user community. Easily modifiable and upgradable to grow with your skill and interest.
It can do aluminum, and if properly upgraded can be used as a small scale production unit.

However, it is not a “production grade” machine. There is a reason why production grade machines usually start at around $4k. It took me over a year of experience with my XC and a few upgrades for me to even begin to understand those differences and why they might mater.
Keep in mind, for a learning machine, a cheaper, lower power approach is not a bad thing. If you screw up, a belt slips, or carve is trashed, but it is an easy and cheep fix. With a high power machine those same screw-ups could be more costly or much more dangerous.

When I was looking at getting a CNC I was trying to compare machines, but really had no idea how to evaluate them.

Resolution? - Higher resolution is better right? Turns out no so much, because the resolution specifications are usually base on “micro stepping”. (You want micro stepping, because it creates a smother movement, but don’t count on the “extra” resolution it creates when comparing machines.)

Carve Area? - Large is better right? Being able to do a full sheet (4’x8’) of plywood or MDF would be best?
In theory maybe. But being able to carve a full sheet of plywood means you have to be able to purchase and transport full sheets of plywood. Turns out this is not as easy as I thought it would be. They are heavy and a pain to carry in from the car. (and clamping it in place would be problematic as well)
I have upgraded my machine to carve longer, allowing me to carve on a 1/4 sheet (2’x4’) and I love it. I can purchase precut 1/4 sheets (2’x4’) from the hardware store, throw them on the XC and carve. So a slightly longer carve area is a real luxury. But unless I had a pressing need I would not consider anything larger. For doing aluminum specifically, you might want to look at a smaller machine. Shorter rails mean less flex under load.

It turns out almost all of the kits I have see use similar designs and materials which means that there resolution and performance will be similar. I think it really comes down to a few factors.
Belts vs Screws.
Belts are cheep, easily expandable (to make a longer axis) and in the case of an accident, probably slip before anything more expensive breaks or you crush a finger. However, they do stretch and flex and have a lower gearing ratio. All of which can effect carve quality.
Screws, offer a higher gearing ratio (finer resolution) and with a anti-backlash nut - less backlash / flex. But are more expensive and have a max length they can go.
Router vs Spindle.
A $120 router is cheep, easy to replace / repair but has a much higher RPM. Not too big of a deal when cutting wood or MDF, but can be an issue with metals.
A water cooled spindle is quiet, higher power and generally can do slower RPMS but is going to cost significantly more.

A lot really depends on what you want to get out of it. If you are looking for a learning machine that you can make some MDF prototypes to refine before out sourcing it for production then the XC is a good way to go. If you want a small scale production machine, then I recommend either being prepared to upgrade your XC as you learn more, or look at some additional CNC kits to see if they may fit your needs.

For additional CNC kit options I recommend you also take a look at:
cncrouterparts
openbuilds
smw3d

17

Hey Guys,

Thanks for all the great discussion. It’s pretty clear that for any kind of production these solutions are not the way to go. I’d still really like to get my feet wet with CNC, and think I can do prototype iterations in a hardwood instead of aluminum. I’m fine with a small investment for that purpose, while going to a shop to order any significant amount. After I get through the initial reading I’m doing on CNC, I’m just going to have to take the dive into ordering one. It makes me feel better knowing a machine like the X is easily upgraded.