[griffindodd]

Hi all,

As the title says I am looking to start into building my own CNC machine for hobby use but I keep getting overwhelmed by all the technical jargon and language that no-doubt seems basic to the initiated but scrambles my rather nooby brain.

I haven't done any machining in the past, I have a reasonably nice collection of hand/power tools from my hobby as an Arcade machine builder and designer but I dont have anything like a drill press or lathe. I'd like my CNC to be my primary tool in creating my arcade machines in the future.

I'd like to build a CNC machine that would compare to or better the accuracy of a blacktoe but with a cutting area of 48"x48". I'll need to be able to cut up to 3/4" MDF or particleboard and maybe some plastics and aluminum sheet up to 1/4" thick. Id would be nice to be able to do some relief carving in wood up to 5" deep, but not a must have.

My primary goal is to have a tool to build with, rather than spending too much time and money building the tool itself. That being said I do enjoy learning from new projects so if it makes financial sense to do a lot myself while learning then of course I don't mind putting in the time.

I know I could get into a fully functional Blackfoot with 4'x8' cutting for about $5,000 including spindle, dust extraction and table. So my question is, could I get into a 4x4 building it myself for around $1,500 for the rig with all electronics?

Just trying to work out if I would really benefit from building from scratch or not.

If so, I really need a good beginners design to start on, written for non-cnc folks using layman's terms and techniques.

Many thanks

[ger21]

So my question is, could I get into a 4x4 building it myself for around $1,500 for the rig with all electronics?

Probably not. Depends on the level of quality and performance you're looking for, but $1500 is tough, even at the low end of both.

I know I could get into a fully functional Blackfoot with 4'x8' cutting for about $5,000 including spindle, dust extraction and table.

Imo, a Blackfoot is incredibly overpriced for what it is.
There are far better alternatives, for much less money. I'd look at either a CNC Router Parts, or a rack and pinion Joes Hybrid. With very good electronics, and a decent VS router for the spindle, both can be built for around $3500 (+ software) and both will blow the Blackfoot away.
CRP4848 4' x 4' CNC Router Kit | CNCRouterParts

Kits & Plans

If you buy the kit from Joe, they both are basically bolt together machines.

[Walky]

I absolutely agree with Gerry. Anyway, if you want a production machine, your best bet is to spend extra and get a machine capable of continuous work such as those from CNCRP, with good support and a wide user base. Even if you were able to build a $1500 4"x4" machine, it might not be very reliable, and the build might end up being much more expensive (most first build budgets grow a lot, just ask anyone here how many unused expensive parts they left unused after each machine iteration/repair/improvement).

[griffindodd]

Thanks for the guidance guys. I font know that I would need production grade equipment but obviously I would like something reasonably reliable.

Could you help me understand the details of why a unit like the ones recommended here are better than something like a blackfoot ? Those are the types of details I really need to understand properly in this decision making process.

Sent from my pocket ZX81

[ger21]

All metal vs plywood. Blackfoot is very flimsy construction, especially in the spindle mount and gantry sides.
Rack and pinion vs chain drive. Chain drive is very low resolution, and isn't as smooth as rack and pinion. Chain needs to be very tight, which puts a lot of stress on the wood where the bearings and sprockets are mounted.
Much more rigid bearings. While the Joes uses V Bearings as well, the Blackfoot runs them on 1/8" aluminum, which is softer and more flexible than the steel the Joes uses. CNCRP uses 1/4" thick steel bar.
Performance. While the blackfoot claims high rapid speeds, they tend to have very low acceleration, which is very important. Also, if you read through their forum, you'll see that cutting speed is usually limited to about 100ipm due to the machine flexing at higher speeds. The other machines are far more rigid, and can cut at 400ipm or more.
Also, most Blackfoot users use cheaper chines drives, rather than the much better Geckos.

I'll go as far as to say that there isn't a single thing the Blackfoot does better than the other two I mentioned. When compared to them, the Blackfoot is slower, much less rigid, less precise, and more expensive.

[griffindodd]

Excellent. Thanks so much for taking the time to help me understand these fundamentals, I'm feeling smarter by the minute.

I saw at the CNCRP site there we two motor and driver packages for the CRP4848, the Nema 23 and Nema 34, quite a massive price difference between the two. What situations would call for the 34 over the 23?

Baring in mind what I have stated as my proposed use for my future CNC, would the 23 be adequate?

Also very random question, but when cutting reliefs as deep as 5" or so, do you have to use a bit that is 5"+ long? Trying to work out how you could get precise details in tight Z areas any other way - just a random thought.

Many thanks

Joel

[ger21]

The Nema 23 are more than adequate. You wouldn't need Nema 34's unless you planned to cut through 3/4" sheets in one pass at high speeds, which would also usually require a 4-5HP spindle.

As for your 5" deep relief. Realistically, it's not going to happen, unless you do it in layers, and glue the layers together after cutting. You just can't get tools that long, and even if you did, they'd be very fragile. Generally, 1-1/2"-2" is about all you can do, if the carving has steep vertical walls.

[roundrocktom]

just ask anyone here how many unused expensive parts they left unused after each machine iteration/repair/improvement).

At least my 1" rods and linear bearings made a nice panel saw!

Motor's -- get the Nema23 - they are fine and have more steps per revolution, so you can get finer detail. Nema34 would allow faster speeds, so if I was running a commercial sign shop I'd opt for those.

I bit the bullet and built a pretty heavy 48" x 48" machine - search for Kronos KRMx02. $4700 BOM total cost ($700 is an optional extruded aluminum table, I opted to use MDF for the time being). So $4000 for the machine (including a router and Mach3).

Joes Hybrid looks pretty interesting. Note sure what his pricing comes in, but I suspect maybe $2500?

Either way the biggest learning curve is the CAD-CAM-MACHINE. I'm using Vetric's Curve Pro for the first two, and MACH3 to run the machine.

[harryn]

It might be helpful to look for like minded cnc router people in your area, and see if you can team up with someone. While I am attempting to do the same as you (more of less only have room for one major stationary power tool), what would be nice is if I could share one with someone else.

Realistically, the operating time / utilization of even serious hobby routers is probably 5 %, at best. Of course there are some commercial / semi commercial users here, but for myself, I am estimating 1 - 3 % actual use time. This gives a lot of opportunity for sharing / paying for use time on a system.

The time to build one of these is actually pretty long. One of the fastest I have seen is jharvey and some drag out for years.

Consider to post what town or region you live in on cnczone to see if you are close to anyone. You might also find someone by posting your interest on craiglist and searching there for cnc. Cabinet makers and small / medium wood shops might be willing / able to cut your parts during less busy times for a reasonable price.

[Crevice Reamer]

I keep getting overwhelmed by all the technical jargon and language that no-doubt seems basic to the initiated....

Hi Griffin. Welcome to the Zone!

Click the link and scroll down on this page for some basic jargon explained:
Page 2

CR.