[adt2]

Hello, all -

As you can see from my post count, I'm new around here. Looks like a huge trove of information if one can sift through it all to find the relevant nuggets. I'm looking forward to becoming a regular.

In the meantime, I need some advice. I recently purchased the plans for the 24x48 machine from Solsylva CNC Plans~ Home Page. I'd like to build it with a 24x96 table. For the time being, 100% of what I do with the completed machine will be to cut flat parts out of sheet stock (MDF and/or plywood), mostly to use as templates for parts being made in my workshop out of solid hardwood. I'm sure that as I get time under my belt with the machine, I'll come up with other uses for it, but for now, all I want is to be able to make through-cuts in sub-3/4" material.

It appears from reading the manual that leadscrews are the way to go (as opposed to belts, chains, or rack & pinion). The manual also mentions HobbyCNC and Xylotex, Mach3 and TurboCNC.

Before I go any farther (i.e. start cutting up lumber and visiting the hardware store), I just want to get a reality check from some of you guys that have already gone down this street. Are HobbyCNC and Xylotex the only ways to go? What about Mach3? I ruled out TurboCNC because it doesn't appear to have been updated in three years; I would like to know if there are other (better) alternatives to Mach3. It may be the bee's knees, but it looks like Ray Charles did it at night. I know the interface can be customized, but come on - I don't want to design software, I want to butcher wood.

That having been said, I'm a bit confused by the other software options out there. My workflow (for now) will be AutoCAD 2D drawing to CNC machine. In the future, I will surely add Rhino and/or SolidWorks to CNC machine. And it just occurred to me - does any of this software perform panel layout (i.e. sheet goods optimization)? If not, how are you handling that task?

Thanks in advance for your input. I'm sure the answers given will provide me with a whole new set of questions, but I've gotta start somewhere.

[ger21]

For an 8ft axis, rack and pinion would be the way to go. Most newer machines you see here are rack and pinion, using the parts from CNCRouterParts

Any axis over 4 ft will usually suffer from screw whip at higher speeds when using screws.

Are HobbyCNC and Xylotex the only ways to go?

5 years ago they were, but the preferred drive today is the Gecko G540. It can offer double the performance of the other drives in it's price range.

What about Mach3?

Most people are using Mach3, by a large margin. EMC on Linux is probably the second most popular.

There are lots of alternative Mach3 screens available, both free and for purchase.

My workflow (for now) will be AutoCAD 2D drawing to CNC machine.

There's usually a CAM program in between, that creates the g-code for Mach3 to run. The most popular for router users are made by Vectric. They're V-Carve Pro package does nesting at a reasonable price.
Most optimizers used in commercial shops tend to start at several thousand dollars and go up. But they're much more specialized.

I use a VBA macro in AutoCAD to create most of my g-code. You can get it at my website.

[Treischl]

Hello, all -

As you can see from my post count, I'm new around here. Looks like a huge trove of information if one can sift through it all to find the relevant nuggets. I'm looking forward to becoming a regular.

In the meantime, I need some advice. I recently purchased the plans for the 24x48 machine from Solsylva CNC Plans~ Home Page. I'd like to build it with a 24x96 table. For the time being, 100% of what I do with the completed machine will be to cut flat parts out of sheet stock (MDF and/or plywood), mostly to use as templates for parts being made in my workshop out of solid hardwood. I'm sure that as I get time under my belt with the machine, I'll come up with other uses for it, but for now, all I want is to be able to make through-cuts in sub-3/4" material.

It appears from reading the manual that leadscrews are the way to go (as opposed to belts, chains, or rack & pinion). The manual also mentions HobbyCNC and Xylotex, Mach3 and TurboCNC.

Before I go any farther (i.e. start cutting up lumber and visiting the hardware store), I just want to get a reality check from some of you guys that have already gone down this street. Are HobbyCNC and Xylotex the only ways to go? What about Mach3? I ruled out TurboCNC because it doesn't appear to have been updated in three years; I would like to know if there are other (better) alternatives to Mach3. It may be the bee's knees, but it looks like Ray Charles did it at night. I know the interface can be customized, but come on - I don't want to design software, I want to butcher wood.

That having been said, I'm a bit confused by the other software options out there. My workflow (for now) will be AutoCAD 2D drawing to CNC machine. In the future, I will surely add Rhino and/or SolidWorks to CNC machine. And it just occurred to me - does any of this software perform panel layout (i.e. sheet goods optimization)? If not, how are you handling that task?

Thanks in advance for your input. I'm sure the answers given will provide me with a whole new set of questions, but I've gotta start somewhere.

Just to get off on the right foot, your workflow will not be from AutoCad to the CNC machine. You will require what is known as a CAM program between the two. That will be something like Vectric VCarve or something similar. The CAM program reads the information that you created in AutoCad. It then converts it into G-Code with some in from you that Mach3 (or another machine control program) reads and uses to drive the machine.

Gerry is exactly right about not using screws on a 4X8 machine. Since you are new to this type of cutting, he did not bore you with the concept that you can cut large sheets of plywood and mdf at quite high feedrates which increases the life of your tool, not to mention saving you a lot of time in the process. Rack and pinion machines can easily achieve rapid traverse rates of 600-1200 IPM and feedrates that would boggle your mind. (I do sculpting work at 300 IPM)

One thing that I would like to add: Building an R&P machine these days is quite easy. You can get all the parts you need cut to length, off the shelf, and it is just a matter of buying nuts and bolts and assembling it.

My first machine was a homebrew, made of mdf, wood, acme screws,etc. It worked ok for 4 years. I typically could not run it above about 70 IPM. I recently built a new one from 8020 extrusions, CNC Router Parts R&P, Gecko 540 Drive package. WOW! It is a 3X4 machine that can rapid at 1200 IPM, I have cut at 400 IPM using a 1/2 cutter. If costs are an issue, I would just hold off a bit, save up a few more dollars and build it once. If you dig a few pages deep on this forum you will see my build log. I did not go crazy buying 8020 extrusion, mounted it all on a wooden table.

As for Mach3. I do not think you are going to find anything better. I would agree with you that whoever did the color scheme is not going to win any awards for artistic flair. But honestly? It works really well right out of the box. You have to set a few parameters because it controls just about any type of machine that exists, but you can get help with that on these forums. A company that has gone from being for the hobbyist to now being used by commercial companies says something about them. And like Gerry said, if you do not like their standard screen, you can download quite a few free screen designs that look a lot better. Me? I have gotten used to the weird colors.

[adt2]

For an 8ft axis, rack and pinion would be the way to go...
Any axis over 4 ft will usually suffer from screw whip at higher speeds when using screws...
5 years ago they were, but the preferred drive today is the Gecko G540...
There's usually a CAM program in between...the most popular for router users are made by Vectric...

Much obliged. The Solsylvan plans, while thorough, assume a certain amount of familiarity with the CNC world. My familiarity is limited to knowing what the machines can produce and not necessarily how the inner workings function. This is exactly the kind of advice I was searching for.

Follow-up question: Would you recommend R&P for all axes, or just the X-axis (~96")?

[adt2]

...you can cut large sheets of plywood and mdf at quite high feedrates which increases the life of your tool, not to mention saving you a lot of time in the process. Rack and pinion machines can easily achieve rapid traverse rates of 600-1200 IPM and feedrates that would boggle your mind...
As for Mach3. I do not think you are going to find anything better...

Again, much obliged. I'm interested in "the theory" of CNC work in addition to the nuts & bolts of building the machine.

Follow-up question: You have any familiarity with EMC2? I downloaded and burned the *.iso image last night, although I haven't had time to play with it. I like open-source stuff when I can find it.

[johnmac]

Use R&P on the X and Y, and an acme or ball screw on the Z. That way the Z will hold its position when the power is off.

John

[Treischl]

I am only familiar with EMC2 to the point that I looked at it when I built my new machine. It sounded like a lot of screwing around. Editing text files, HAL, ladder logic, etc. You made a statement in your original post about not wanting to design software? Hmmmm.

There are reasons that a product has a huge following. When it comes to a product like this, it is usually because it works well and doesn't drive people crazy.

[ger21]

Just to get off on the right foot, your workflow will not be from AutoCad to the CNC machine.

It is for about 90% of the parts that I make, using a macro to create my g-code in AutoCAD.
The CNC Woodworker

[adt2]

I'm giving some thought to the suggestion above to hold off a bit and build the machine "the right way" the first time. I've got a question about the 80/20-type aluminum extrusions.

I envision my machine's base being roughly 36" x 96", although I may decided to upsize to a base that'll handle a full sheet of plywood (I've got a 32' x 40' workshop, so space is not really an issue). What size extrusions would be appropriate to support the table top? I'm thinking something like two 8' rails along the X-axis, plus say 5 cross-beams along the Y-axis spaced 2' apart. Is 15-15 beefy enough?

I figure the heaviest thing I'm likely to put on the table is a full sheet of MDF, which weighs ~90 lbs, or roughly 3psf - which seems to be well under the limits of the 15-15 for a uniformly supported load.

[adt2]

Treischl -

After reviewing your new build post, I see that I am (once again) wrong about a number of things. Doesn't look like I need to build my table base out of 80/20; looks like that should be a wood structure with a torsion box top plus a sacrificial top on the box. It appears that the motion system (i.e. axis rails and what-not) are the parts utilizing 80/20 stuff.

Follow-up question: Are the "trucks" that your gantry rides on homebrew items, or did you source them somewhere? How do they interface with the 80/20 rails?

[samco]

It is not that bad.. there are wizards to help setup the machine. If you want to get into the nuts and bolts of emc - you can.

sam

I am only familiar with EMC2 to the point that I looked at it when I built my new machine. It sounded like a lot of screwing around. Editing text files, HAL, ladder logic, etc. You made a statement in your original post about not wanting to design software? Hmmmm.

There are reasons that a product has a huge following. When it comes to a product like this, it is usually because it works well and doesn't drive people crazy.

[Treischl]

It is for about 90% of the parts that I make, using a macro to create my g-code in AutoCAD.
The CNC Woodworker

AutoCad, out of the box does not produce G-Code, it requires macro programming. I know, I have been using it since about V 2.0

[Treischl]

It is not that bad.. there are wizards to help setup the machine. If you want to get into the nuts and bolts of emc - you can.

sam

Yup, "It is not that bad", and I am still waiting for Linux in one of the many variations to take over the computing world.

[adt2]

Just to get off on the right foot, your workflow will not be from AutoCad to the CNC machine...

No need to go off on a tangent here. What I was trying to say was that I do my design work in AutoCAD, and my intent is to draw in AutoCAD and then send to the CNC machine (as opposed to learning to design in some other piece of software). I understand that there is generally an interpretor between the two.

[adt2]

Yup, "It is not that bad", and I am still waiting for Linux in one of the many variations to take over the computing world.

I tend to agree. I downloaded the manual for EMC2, and they lost me on about page 2 where they start talking about gathering data for your parallel port pinout without a single mention of how to go about doing it. I'm a technical writer by trade, and it makes me crazy to see "instructional guides" that go from Step A to Step Z without so much as a summary of Steps B through Y.