Hello - first post here. Just discovered this site. I have been recently thinking about building a CNC router. Having never done it before it seems easier to go with a plan than thinking it out from scratch. I found the solsylva site and since coming here I see a few people using those plans.

Are there any other designs or plans worth looking at

I'm a newbie too, so please take my comments with a grain of salt.

I bought the solsylva plans. They are really nice, however do not talk about the electronics much at all, so there is much to learn there.

If you are planning to follow plans exactly, then get the plans.

If you are planning to make a modification of the plans, I found the plans almost useless.

I'm free styling my machine based on what I could obtain on e-bay. I'm sure it would have been easier and cheaper to follow plans exactly, however I am enjoying my build.

I'm using basically everything I have read on problems here and making a machine which tries to not recreate the previous screw ups. (Yet... making plenty of screw ups / workarounds myself.)

blue_can,

Three other popular designs are the Rockcliff, JGRO, and Joes CNC Model 2006 and you will find the info for them on CNCzone. There are others out on the internet.

Solsylva plans are intended for first time builders who don't have a lot of tools and the cost is kept low by using locally available parts as much as possible. The general machine designs are good, but the hardware can be improved on.

There are a lot of people who built machines from the Solsylva plans and made changes to the dimensions to allow use of larger and better leadscrews, anti-backlash nuts, larger bearings, and made the machine larger for their needs. The plans are very detailed. If you are going to deviate from the plans you will have to understand how the hole locations will need to be enlarged or moved in order to accomodate the larger or differently shaped parts. The 25x37 and the larger belt drive machine plans are very open to design improvements to make them much better than if built strictly by the plans. People are successfully using the 25x37 to make guitar bodies, R/C model kit parts, and 3D craft objects.

The first thing to change is the use of pine lumber. Use something more stable and harder. The second thing is don't use all-thread rods. They will work, but few people have been happy with them long term. All-thread rod is rough, inaccurate, generally not straight, and very slow when it does work without binding.

CarveOne

georgeburns (http://www.cnczone.com/forums/member.php?u=67701),

There is some useful information about the electronics on the Solsylva web site. The plans don't go into the electronics parts because those parts change too often as the technology evolves. PINMO's website is an excellent source for information also.

CarveOne

Here are my thoughts:
Like you, I have been looking into building my own CNC machine. I have not gotten as far as you in regards to the acquisition of the parts.
One of the issues that has been a priority for me is the one of accuracy, if you want to make accurate parts you should start with an accurate router/mill.
Most of the DIY plans out there start with flat parts as the body of the machine. And I am learning, the hard way, that when you cut a flat part (by hand since you do not have a router yet) it better be dead nuts. The other issue, quite critical, is the way the holes in the part are drilled.
Usually a hole in a DIY design will either serve as an attachment to the adjacent parts or more critically as a shaft support. The holes better be 100% perpendicular or else.
Drilling a hole on a plate is more complex than it seems since even when using a press there is no warranty that the bit will not snake (bend) all over.
I strongly recommend that if possible, have the critical parts laser cut out of steel (if needed these parts can be stacked in order to achieve the desired thickness.
Cutting the parts by laser does present a challenge: try to find a vendor that will cut the onsies and two sies and one that takes you seriously enough to even look at your drawings and return you the parts on a reasonable time and price. I do a lot of prototyping and this issue has become quite critical to me.
Maybe trough this forum somebody can suggest a good source for laser cutting. Sometimes I am tempted to to look for a good DIY plan to make a laser cutter instead.
Also, make sure that the router that you will use is reliable and powerful. For some reason Dremels are not as good as they used to (so far I have had two of them melt in my hand when cutting soft metal).
ED
Maybe trough this forum

Thanks for the replies everyone. I will take a look at the other plans mentioned. This site does have a lot of info – it’s just case of spending the time to go through a lot of the posts and stickies.

I did understand looking at the Sylsolva web site that the plans are really for the tables only and that learning about the electronics is additional. I was not that concerned about this being an electrical engineer myself. I have designed quite a lot of board level electronics in the past as well as software and mainly these days am involved with designing and developing integrated circuits. Having said that I have not done much work with stepper drives but it should be relatively easier than the stuff I design (audio, video, wireless and so on).

For the mechanical assembly I do have some limited metalworking capability including a 4X6 metal bandsaw which is quite good at cutting stock quite accurately.

My main motivation for being interested in designing and building a CNC is that I’ve got into stone fabrication as a hobby. Since I fabricate by hand I have started needing good templates to use as guides for the various cutouts. I’ve just had a shape (very simple) cut out at a local CNC place and based on the cost it does make sense to try and build my own CNC router – plus it would be a fun project.

http://www.buildyourcnc.com is a web site you might want to look at. There are detailed videos showing the entire build of an MDF machine. I am planning on building one based on his version 2.0, which looks very solid.

Here is a tip!
Save your Money and build a real Machine!

Blue can

Try searching the web for MechMate. It is a well designed work horse of a cnc router. The plans are free . And the other do-it-yourself's offer build support. Everything you need ,including the electronics, is explained. But, be prepared to read the plans thoroughly for all the build info. The guys on the site don't like to hand everything to you on a platter if the info can be found in the plans. Total cost varies but be prepared to spend as much as $6000.00 to build a 5'X10' router. The plans are scalable so the size is your choice. And you can spend the money over as long a period as you like. Some guys build theirs in months some take years. It's your choice.

Paul

If you're not into spending a whole of money for this and just like it as a small(ish) hobby, you could build your own machine for much less than $6000. Given, the $6000 will get you a much sturdier and faster machine, but with $500-800 you can build something that will still do a good bit. It'll just take some hobbyist ingenuity.

Hi Blue Can,

I would suggest taking a look at www.modularcnc.com. I sell cnc router components and 3-axis machines for the hobbyist and light industrial markets. Everything from simple motor mounts and single axis slides to 3 -axis aluminum machines. There are even some videos of my machinery cutting on the site as well. This is a great hobby to get into take your time with your machine designa dn learn as much as you can.

Andy

Great info. I will check out all the links provided.

Andy – I had a look at your site but I was hoping to build something larger and something capable of carrying a full size router – not a Dremel type tool. However, I do have a space constraint in my garage with all the other tools and projects going on. One idea I have is that I do have a steel table (5’ X 3’) which I built about a year or two ago. It weights about 250lbs so if I could make a study router that could be bolted onto the table that would form a good base for it. The table top is a steel plate which could be drilled and tapped.

I notice that many plans use Aluminum but since I do have the ability to cut steel, maybe using steel would provide a firmer design. As far as metal supplies – not sure about most here but I’ve found the best prices and selections at a steel yards rather than at home centers like Home Depot. Not only are the prices cheaper at steel yards but sometimes if I can use remnants they have pretty much given me the steel stock for free (depends how much they have and how much you want of course). Also the selection is huge.

My neighbor was recently getting rid of a desktop computer and ask me if I wanted it. I took it although I really had no idea what I could use it for. I think this is the ideal application for it – the controller for the CNC.

I looked at a couple of software packages about 2 days ago – Mach3 and KCAM4. I was a bit disappointed that both had difficulty displaying an ellipse that I had drawn using TurboCAD. The CNC place that routed the design for me was able to read it so maybe these software packages are not upto date or something.

I see there is a forums for this kind of question so maybe that is a better place to ask.

Great info. I will check out all the links provided.

Andy – I had a look at your site but I was hoping to build something larger and something capable of carrying a full size router – not a Dremel type tool. However, I do have a space constraint in my garage with all the other tools and projects going on. One idea I have is that I do have a steel table (5’ X 3’) which I built about a year or two ago. It weights about 250lbs so if I could make a study router that could be bolted onto the table that would form a good base for it. The table top is a steel plate which could be drilled and tapped.

I notice that many plans use Aluminum but since I do have the ability to cut steel, maybe using steel would provide a firmer design. As far as metal supplies – not sure about most here but I’ve found the best prices and selections at a steel yards rather than at home centers like Home Depot. Not only are the prices cheaper at steel yards but sometimes if I can use remnants they have pretty much given me the steel stock for free (depends how much they have and how much you want of course). Also the selection is huge.



Look at Ahren's router parts (cncrouterparts.com). These will probably suite your needs better for the larger table. If you bolt the steel rail in the proper orientation to the aluminum extrusion, you and quite a bit of strength. Also, even if you decide to just use steel for the frame, his parts could mount pretty easily to it.


My neighbor was recently getting rid of a desktop computer and ask me if I wanted it. I took it although I really had no idea what I could use it for. I think this is the ideal application for it – the controller for the CNC.

I looked at a couple of software packages about 2 days ago – Mach3 and KCAM4. I was a bit disappointed that both had difficulty displaying an ellipse that I had drawn using TurboCAD. The CNC place that routed the design for me was able to read it so maybe these software packages are not upto date or something.

I see there is a forums for this kind of question so maybe that is a better place to ask.

Make sure the computer is fast enough to run the software. I know several people on here had problems because the computer was so slow Mach couldn't pulse fast enough and they were losing steps.

As far as software, I use EMC instead of Mach. Very good program, very easy to install, requires less powerful hardware to run, and it completely free...Couple that with Vectrics V-Carve Pro and SolidWorks and you have a package that can do practically anything you can dream of. A note about TurboCAD though. Did you generate G-Code for the Ellipse or try to import the part directly?

Make sure the computer is fast enough to run the software. I know several people on here had problems because the computer was so slow Mach couldn't pulse fast enough and they were losing steps.To touch on that, as long as it's around 800MHz you're probably fine. 500MHz is where I've seen people having trouble.

Hi Blue Can,

Thanks for the feedback. I am working on a larger machine design but its hards to come up with something that will suit many needs, be sturday and rigid, and also capable of shipping easily.

My aluminum machine is actually capable of running a full size router. I have a video of it shown making 7/16" cuts through MDF without even blinking and that is with the Harbor Freight 1/4" Laminate trim router.

Steel is an ideal choice to build your machine from. It is strong, cheap, and absorbs alot of vibration which reduces chatter and improves finishes.

Andy

Look at Ahren's router parts (cncrouterparts.com). These will probably suite your needs better for the larger table. If you bolt the steel rail in the proper orientation to the aluminum extrusion, you and quite a bit of strength. Also, even if you decide to just use steel for the frame, his parts could mount pretty easily to it.



Make sure the computer is fast enough to run the software. I know several people on here had problems because the computer was so slow Mach couldn't pulse fast enough and they were losing steps.

As far as software, I use EMC instead of Mach. Very good program, very easy to install, requires less powerful hardware to run, and it completely free...Couple that with Vectrics V-Carve Pro and SolidWorks and you have a package that can do practically anything you can dream of. A note about TurboCAD though. Did you generate G-Code for the Ellipse or try to import the part directly?

I'm not sure exactly how old the computer is (I've not booted it up yet) but it is not too old. So I guess it should be fast enough for this application.

I will check out the EMC software. Got a link for that? I could not find it on the web. As for the ellipse - this was a design that I needed cut on a CNC and a local CNC place did that. I saved the file as a dxf. I tried to open the file in both the software packages - both were able to render the circles and the rectangle but not the ellipse. I think one of them (I think Mach3) gave out a message like "unrecognized command - ellipse" or something like that.

Not sure why this is - since an ellipse can be exactly defined by an equation - once you have the major and minor diameters - it should be able to calculate all the necessary points on the locus.

I created an ellipse in TCAD v12 and imported it into CamBam with the same results. An ellipse is a commonly used frame, or border, for rectangular signs. Don't have a clue as to why the gcode converter chokes on these shapes. It gives an "unhandled entity: ELLIPSE" error message. This was a variable ratio ellipse. I didn't try the fixed ratio type of ellipse, but I doubt that it would matter. If CamBam identifies it as an ellipse entity it probably knows that it can't calculate the coordinates of either type. At least not until the feature has been added. I used the trial version, so maybe the full version supports it.

EMC2 is at www.linuxcnc.org/ (Requires Ubuntu Linux operating system)

CamBam is at http://www.cambam.co.uk (Requires Windows operating system)


CarveOne

Thanks CarveOne. Since the computer probably has a lot of junk on it I guess this may be a good time to reformat the hard disk and install Linux.

Not sure why these packages have issues with an ellipse. If my meory serves me correctlly the equation for an ellipse is (x**2/a**2) + (y**2/b**2) = 1 (** 2 = squared a,b are the major and minor diameters). If you make a=b=1 you get the equation for a circle. I cannot understand why these packages should have difficulty implementing something like this.

I guess the EMC2 packages can do ellipses :)

blue_can,

As if by magic, I received an email notice from CamBam last evening with the following new feature in the latest beta release:

--------
DXF Ellipse support


<!--[if !supportLineBreakNewLine]-->CamBam should now be able to read ELLIPSE entities from DXF 2000 files. Currently these are converted to polylines with line segments with 120 segments for a full ellipse.

-----------

You can check it out here:
http://www.cambam.co.uk/download/latest/cambam-plus-beta-release-093.html

I'm sure they would appreciate you doing some tests of this feature for them if you don't mind using beta software. Just rename the file that CamBam creates with a .ngc filename extension and it will run in EMC2. The native CamBam output file should work with Mach3.

As I thought, the gcode generator is the software that has to understand how to handle the ellipse in a dxf file and create a tool path for it. I'm sure they would appreciate you doing some tests of this feature for them if you don't mind using beta software. Just rename the file that CamBam creates with a .ngc filename extension and it will run in EMC2. It works that way for the previous version that I have been using. The beta is limited to 30 uses.

CarveOne

Not sure why these packages have issues with an ellipse. If my meory serves me correctlly the equation for an ellipse is (x**2/a**2) + (y**2/b**2) = 1 (** 2 = squared a,b are the major and minor diameters). If you make a=b=1 you get the equation for a circle. I cannot understand why these packages should have difficulty implementing something like this.


Because there is no "standard" g-code to do an ellipse. Some CAD programs (AutoCAD I know can) can approximate an ellipse with a tangent arcs. While not a true ellipse, it is very close and should pass for most instances. See if TurboCAD can do this. You're other option is to break the ellipse into a serious of very short straight segments. Again, you'll need to see if your CAD program can do this. Or use a CAM program that can. This is probably what CAMBAM is doing.

Some more expensive controls do have proprietary g-codes for cutting ellipses, but unfortunately, Mach3 doesn't. But as I mentioned, there are a few simple workarounds that can get the job done for you. If you need an ellipse drawn with arcs, you can PM me and I'll send you one.

To be honest it is not that I have a big need for routing ellipses but since I happened to need it on this first design and I tried to open the dxf in all of these software packages and since none of them could draw it I wondered what other things were missing.

I guess don't know enough about g-code to understand why ellipse support has not been provided. If as you guys are saying that g-code cannot interpet an ellipse surely all that the software has to do it to take in the paramters from the ellipse, calculate the necessary points on the locus using the ellipse equation and then join them using a simple mechanisms. I presume given enough points you can even join them using straight lines from one to the next.

I will try out that version of Cambam and see if it works.

Of the CAD programs I've used (not many expensive ones) they all draw curves on-screen and on paper using line segments. The lower the screen resolution the longer each segment seems to be to the point of looking very jagged. It becomes more apparent as you zoom in on the curve when using higher resolution screen resolution. The jags don't show in the finished work unless using a very rigid machine and small engraving bits in something hard like aluminum, brass, and steel. Otherwise, the mechanics tend to average out the jags during the cuts.

Maybe the sheer number of calculations required for no jag ellipses would unacceptably bog down all but the most powerful computers. Maybe some trade off was necessary in the early days of CAD software and slow computers that continue today. (Just speculating based on no knowledge of the subject. :))

CarveOne

Of the CAD programs I've used (not many expensive ones) they all draw curves on-screen and on paper using line segments. The lower the screen resolution the longer each segment seems to be to the point of looking very jagged. It becomes more apparent as you zoom in on the curve when using higher resolution screen resolution. The jags don't show in the finished work unless using a very rigid machine and small engraving bits in something hard like aluminum, brass, and steel. Otherwise, the mechanics tend to average out the jags during the cuts.

Maybe the sheer number of calculations required for no jag ellipses would unacceptably bog down all but the most powerful computers. Maybe some trade off was necessary in the early days of CAD software and slow computers that continue today. (Just speculating based on no knowledge of the subject. Drawing perfect circles can become a very computationally intensive task. If you're using AutoCAD, there's a setting for how many lines to use to render circles. You can set this anywhere from 4 to several hundred thousand. Obviously, the higher you go the more refined the circle appears. However, onces you start making several dozen (or even hundreds) of circles, arcs, and ellipses, your computer will most assuredly start to slow down immensely.

The key understanding is that a computer doesn't understand circles and arcs. It understands lines. 3D graphics are generated from flat surfaces - polygons. The more polygons, the smoother it appears.

Well it depends how you look at it. It really depends on the software. Even for drawing lines, the computer needs to calculate the points on the line and then connect them to form the line. To draw a line all you need are 2 points on the line and then you can solve for the equation y = mx + c.

Similarly for any shape like circles, ellipses, parabolas and anything that can be represented by an equation. If you are drawing these shapes with lines the system will have to probably compute the points on the shape and then compute the points on the line joining each of those points which is probably why it becomes computationally intensive. Of course the more points you have the longer it takes to compute those coordinates in order to display and the more complex the equation the longer the computation will take. A line is a first order polynomial whereas circles and ellipses are second order.

But I agree with CarveOne that a shape that has a jagged edge on the screen will probably come out a lot smoother on the machine due to the inertia of the system – that should provide some form of low pass effect.

I'm thinking that the low pass filter effect that blue_can mentions will almost disappear if the router machine is nearly perfectly rigid and accurate. Conversely, a more marginal machine will lessen the appearance of the jaggies.

I think my own first build cnc machine will not have a problem with being too rigid or too accurate. I'm just hoping the first ellipse I cut doesn't have big irregular sine waves on the ellipse's cut line. :) :)

CarveOne

That's an interesting point. Bear with me as I'm new to this whole CNC thing but is it possible to build a CNC router with adjustable damping so that the filtering effect can be modified. Is that something that can be done on CNC machines. I can see it would be useful for smoothing out cuts in certain situations.

I'm not too sure that it would be of any benefit with steppers because they make incremental moves anyway.

What I'm getting at is that a "looser machine" will tend to smooth out the jags with mechanical errors due to flexing and loose fitting parts. I doubt that there is a good way to vary the filtering other than to do it with tensioning screws or rods. The Solsylva 25x37 I built has a couple of all-thread rods in the z axis for fine adjustments to the skate bearing contact with the pipe they roll against. They pull the side plates together to physically move the bearings a little.

A mechanically "perfect" machine will transfer to the cuts anything that the software and controller board throws at it. If the software shows jaggies on the screen but the electrical output to the controller board makes all the points in the ellipse in a single curved line then the cuts on the "perfect" machine will be a smooth cut if servos are used. What you see on the screen is not necessarily the same as the electrical output to the controller board. I suppose that some kind of adjustable electrical filtering circuit could be added to the controller board that might be used to smooth out anything in the electrical output. They may already be using it in servo controller boards.

CarveOne