Another newbie jumpin onto the CNC train :)

[SpyderHelix]

Howdy all,
A little about myself: I've been interested in machining (or at least, working with my hands) since I was a kid..always tinkering with things or having a hare-brained idea that I wanted to create..
Got laid off from a major cabinet manufacturing plant and as a result, was able to go back to school for a 2 year degree on a free ride - so I decided to become a machinist.
Fast forward 2 years and a graduation later, and here I be!
I work at a machinist shop here in town, and have always had a fascination with CNC machines so I have decided to throw myself into a new hobby and make a home CNC machine.
Bought some plans online, went through the parts list etc and thought it would make a good machine (although, made of hardwood) and I've been rethinking the machine and its assembly. A machine made of wood would be fine for wood cutting, but I want to build something that can cut wood, plastic, soft metals (brass, bronze etc) and some aluminum with light cuts and hold decent tolerances.

Now I'm at that dilemma where I'm not sure to continue with the plans that I've got (I've bought 1/2 the materials or so for it) or should I adapt the plans into something framed in aluminum instead?
I'm working on a budget of "work overtime pays for the materials" so I want to do this the right way the first time.

My idea is to use:
*3/8-8 4 start acme thread for all 3 axis
*a grizzly 3" rotary table for a 4th axis (Although I have found an interesting idea using a gear reducer and a smaller 3 jaw chuck..)
*as stated above, be able to use a 4th axis
*a large work envelope - I want to be able to make some things such as carved hope chests etc, so I want that large work envelope to make large carvings (the plans I bought have a 25x25 cutting area)

I have already picked up my controller/stepper set off of ebay: A 4 axis kit with 290oz steppers, power supply etc...and for giggles picked up a dual shaft nema 23 off of MPJ that was on sale for the 4th axis control. (I can save one of the nema's in the original set to replace a failed drive if it occurs)

As a beginner question - should I stick with the all wood machine, or try to adapt it to make the entire thing out of aluminum?
The dimensions are in standard wood sizes, and I think that the 8020 site might have some things that are close, but I'm unsure.
Just hoping to get a push/slap/kick/shove in the right direction that doesn't incur too much scrap
Thanks for any input, and I look forward to doing more than lurking in the future!

[louieatienza]

Howdy all,
A little about myself: I've been interested in machining (or at least, working with my hands) since I was a kid..always tinkering with things or having a hare-brained idea that I wanted to create..
Got laid off from a major cabinet manufacturing plant and as a result, was able to go back to school for a 2 year degree on a free ride - so I decided to become a machinist.
Fast forward 2 years and a graduation later, and here I be!
I work at a machinist shop here in town, and have always had a fascination with CNC machines so I have decided to throw myself into a new hobby and make a home CNC machine.
Bought some plans online, went through the parts list etc and thought it would make a good machine (although, made of hardwood) and I've been rethinking the machine and its assembly. A machine made of wood would be fine for wood cutting, but I want to build something that can cut wood, plastic, soft metals (brass, bronze etc) and some aluminum with light cuts and hold decent tolerances.

Now I'm at that dilemma where I'm not sure to continue with the plans that I've got (I've bought 1/2 the materials or so for it) or should I adapt the plans into something framed in aluminum instead?
I'm working on a budget of "work overtime pays for the materials" so I want to do this the right way the first time.

My idea is to use:
*3/8-8 4 start acme thread for all 3 axis
*a grizzly 3" rotary table for a 4th axis (Although I have found an interesting idea using a gear reducer and a smaller 3 jaw chuck..)
*as stated above, be able to use a 4th axis
*a large work envelope - I want to be able to make some things such as carved hope chests etc, so I want that large work envelope to make large carvings (the plans I bought have a 25x25 cutting area)

I have already picked up my controller/stepper set off of ebay: A 4 axis kit with 290oz steppers, power supply etc...and for giggles picked up a dual shaft nema 23 off of MPJ that was on sale for the 4th axis control. (I can save one of the nema's in the original set to replace a failed drive if it occurs)

As a beginner question - should I stick with the all wood machine, or try to adapt it to make the entire thing out of aluminum?
The dimensions are in standard wood sizes, and I think that the 8020 site might have some things that are close, but I'm unsure.
Just hoping to get a push/slap/kick/shove in the right direction that doesn't incur too much scrap
Thanks for any input, and I look forward to doing more than lurking in the future!

Could I ponder a guess that your plans are from Solsylva.com? You could use extrusion for some of the parts, but then you'll have to make modifications to the plans.

I built one, and with care, was able to cut aluminum with it. A couple others here too like Crane has cut aluminum with his. The nice thing is, once you have one built, you cna make better parts for your machine, using your machine!

I would stick to the plans. Once you build it and see what it can do and what its limitations are, you'll have a better idea of what you need to get to make your machine perform the way you need it. Heck make all the parts out of solid aluminum!

[adprinter]

I would recommend a steel framed system, with as rigid a design as you can possibly afford. The wood stuff may be fine, for the learning experience. But if you want to build right the first time, then a heavy-duty construction is the better way to go. Particularly if you want to machine metals. Have a look at my first build: MyCNCV1.PDF for some ideas. Although dimensions are not inlcuded in the file, since you are mechanically inclined- you should be able to scale it for your purposes. Another member posted a challenge about a month ago for plans to build a machine for under $1000. So, I researched what it would cost to duplicate my machine at today's prices and was shocked at the results! I estimate it would cost about $3500 at today's prices to build this machine. But it really depends on what materials you may already have available to use.

[ger21]

First, tell us what electronics you bought and what plans you have.

so I want to do this the right way the first time.

Which electronics did you buy? A lot of the Ebay options are very poor choices (imo).

If you're plans are for a Solsylva, you might want to reconsider. Almost all members here that have built them have goneon to build better machines. They are really better suited to light duty woodworking.

If you want to cut brass, bronze, and aluminum, you really should get a mill. Generally, as size goes up, rigidity goes down, and rigidity is extremely important when cutting metals. It's possible to build a large, rigid machine, but it will usually cost quite a bit more. But even with a rigid machine, you'll still probably need to take very light cuts, much lighter than with a mill.
If you really need to cut metals, I'd either use a design with some type of supported round linear rails, or CNCRouterParts carriages.

ALso, you'll want to use 1/2" acme, not 3/8". The 1/2" is much stronger and will be less prone to whipping.

[SpyderHelix]

The control set I bought is this one.. And yes, I bought the Sol Sylva plans (I was being vague, because I don't know what can and can't be discussed on the boards regarding plan builders)
I'm fine with taking .010 to .020 cuts, I don't have unreal expectations as far as trying to use the machine to hog material..that won't be feasible with a home machine.
I'm also trying to gather information as to which is "better", a fixed gantry or mobile one..I know more room is needed for the fixed gantry, but I also hear it's more stable and has better tolerances. I wanna try my hand at "high speed machining" on one of these puppies just for giggles, to see what I can make or break later down the line heh.

As far as a mill goes, I don't have the room for anything very large so a full sized mill is out the door - I live in an apartment and have a small breezeway for storage, so I have to put whatever I have there. Plus, no access to 220v: it's a 110 world here.

I chose the 3/8 acme thread because of the 4 start configuration - I've been told that with 4 starts, it wont turn as fast to move the table quickly so whipping would be a very minor problem if one at all.


The majority of work on the machine is going to be wood, plastic and clear poly..other than that, brass, aluminum, and bronze will be for ideas down the line using ultra light, fast cuts.
I guess I'm just looking for an idea of what plans are available that have a decent work envelope, that decent tolerances within .003 - .005" and are affordable to someone on a budget. I'm completely open to reconsidering my build options, but after that I'm not sure where to go. I've done many Google searches for plans and it's just a convoluted process that brings me back to what is popular..which isn't always the best choice.

Is it difficult to make your own from scratch if you haven't built one in the first place?
Should this be something I need to consider rather than going with someone else's plans?

Edit: Just to add, I don't *NEED* a huge work envelope, but larger is better..and as an addition to my question above - a fixed gantry would be best for a large table, correct?

[awerby]

The control set I bought is this one.. And yes, I bought the Sol Sylva plans (I was being vague, because I don't know what can and can't be discussed on the boards regarding plan builders)

[I think you can say anything you want here. But this doesn't sound like the kit that's suitable for a large router. Stick to 12" x 24 or so, and it might work okay for light materials.]

I'm fine with taking .010 to .020 cuts, I don't have unreal expectations as far as trying to use the machine to hog material..that won't be feasible with a home machine.
I'm also trying to gather information as to which is "better", a fixed gantry or mobile one..I know more room is needed for the fixed gantry, but I also hear it's more stable and has better tolerances.


[You've got it right. A fixed gantry (or "bridge") design is more stable, but also takes up more floorspace.]

I wanna try my hand at "high speed machining" on one of these puppies just for giggles, to see what I can make or break later down the line heh.

[You had that right too: "that won't be feasible with a home machine."]

As far as a mill goes, I don't have the room for anything very large so a full sized mill is out the door - I live in an apartment and have a small breezeway for storage, so I have to put whatever I have there. Plus, no access to 220v: it's a 110 world here.

[I hope you've got extremely tolerant neighbors. Cutting stuff with a router is loud...]

I chose the 3/8 acme thread because of the 4 start configuration - I've been told that with 4 starts, it wont turn as fast to move the table quickly so whipping would be a very minor problem if one at all.

[It will over long distances; that's why keeping this machine small is recommended.]


The majority of work on the machine is going to be wood, plastic and clear poly..other than that, brass, aluminum, and bronze will be for ideas down the line using ultra light, fast cuts.

[Good luck with that...]

Is it difficult to make your own from scratch if you haven't built one in the first place?

[Consider this an experiment. Yes, you do get better at it over time and multiple machines.]

Should this be something I need to consider rather than going with someone else's plans?

[Starting with a plan, where someone else has thought about the crucial details, can save a lot of agony...]

Edit: Just to add, I don't *NEED* a huge work envelope, but larger is better..and as an addition to my question above - a fixed gantry would be best for a large table, correct?

[Not necessarily - there's a trade-off between accuracy and size. With a fixed gantry, you've opted for accuracy, given a certain footprint.]

Andrew Werby
ComputerSculpture.com — Home Page for Discount Hardware & Software

[louieatienza]

It would be a myth or fallacy to say that high-speed or constant-engagement toolpaths wouldn't work on a home-made CNC. The reasoning is that if the tool engagement is controlled, there's always a constant load on the spindle and you can then take deeper cuts with lighter stepover and faster feedrate, which with the right settings can up your material removal rate (MRR) over a standard toolpath.

In fact this benefits less ridgid or less powerful machines because you can make them cut at a much faster rate than you could normally do with traditional toolpaths. Why? Because with high-speed toolpaths, the bit never takes a full width cut, and it never gets buried in a corner, where the tool engagement would increase. This may not be a big problem on a mill since they're ridgid enough, but it also means a mill could run much faster. These aren't cuts intended for finishing, they're intended for hogging out material, though they do leave a cool pattern on the pocket floor. The reason being higher speed and climb cutting tends to 'push' the bit away from the cut line; but a finish pass takes care of that.

In fact they're fast enough on aluminum on my machine, that I'll actually pocket out large holes than to try to do a profile cut.

High-speed toolpaths are not necessary on woods since even most DIY machines are ridgid enough to handle the increased tool engagement. I have experimented with then on woods and have been able to increase my DOC and feedrate..

Even with my Solsylva, I was able to do some light aluminum cutting. I won't be hired by an aerospace contractor, but with finish passes, I was able to hold .003" at least, and that's with thin wall aluminum tube and skate bearings. It's not ideal and the finish isn't as good as a mill (though pretty damn good compared to some other attempts I've seen). While I have built another machine to replace my Solsylva, I wouldn't trade the experience; very easy to build, and good accuracy for the price.

Though, as a machinist, you should be able to make something pretty darn good!

[ger21]

The control set I bought is this one.

If you do some research, there are tons of threads here with people trying to get those to work. They're cheap, but you definitely get what you pay for with those drives.

I chose the 3/8 acme thread because of the 4 start configuration - I've been told that with 4 starts, it wont turn as fast to move the table quickly so whipping would be a very minor problem if one at all.

You want 4 starts, but you want 1/2" 4 start. 3/8" is too small.

Im also trying to gather information as to which is "better", a fixed gantry or mobile one

It really depends on how it's built. You can build a moving gantry stronger than a fixed gantry. In general, though, it's easier to build a more rigid fixed gantry.
But the vast majority of people here are building moving gantry's, with no problems.

I guess I'm just looking for an idea of what plans are available that have a decent work envelope, that decent tolerances within .003 - .005" and are affordable to someone on a budget.

The best plans available for a wood construction machine imo are probably the Joe's 2006. The plans are free, too. But you'll need some woodworking skill and tools to build it. Not sure about building one in an apartment, as a lot of template routing is required, unless you buy the pre cut kit. Welcome to Joe'sCNC.com
Now, the Joes 2006 is probably not the best choice for doing any metal work, but I think it's the most rigid one out there.

[HorridHenry]

The control set I bought is this one..

This is a better option than your suggested kit,since you only need 3 drivers and steppers for your build....these steppers are more powerful than those you selected,better drivers and only $6 more.

3 axis Nema23 stepper motor 425oz-in& Drivers CNC controller kit Longs Motor | eBay

[louieatienza]

I'd be more inclined to buy a xylotex kit than the China stuff, if only for the better support. Plus no need to buy a power switch, BOB, connectors for the motors, wires, PSU; it's as plug-and-play as it gets... Only limiting factor is the 30V PSU limit...


Like Gerry said, you can get 1/2"-8, 4-start, and dumpsterCNC makes the AB nuts and couplers for them. Roton makes a 1/2"-6, 2-start (3TPI) but good luck getting an AB nut inexpensively. Kerk I believe even has a 2.5TPI screw.

[HorridHenry]

I'd be more inclined to buy a xylotex kit than the China stuff

So where do you think the motors,psu is made.

[louieatienza]

So where do you think the motors,psu is made.

That's not the point. Jeff at xylotex is easily accessible via email and phone, and there are a lot of successful users here on the CNC Zone including myself. They even have a group in Yahoo. Maybe you have a direct line to Mr. Longs Motor and can speak Mandarin? Or you can visit the Longs Motor user group? To save about $50?