First CNC Build- Joe's

[Ohioflyer]

Hello All,

I thought I had better start posting as I am sure I will probably have lots of questions soon. Let me start off by saying that I have never done any CNC work before. I am a woodworker by trade and by hobby and have always wanted a CNC machine. I have also done quite a bit of electrical work, both AC and DC. The AC side is where I'm most confy, though I I have done electronics assembly as well so a soldering iron and small guages don't bother me. Really what I'm saying is that I hope these skills will get me up and running with my own CNC!
As per the title of this thread I'm building a Joe's 2006-R2. Right off the bat let me say Thanks Joe! Very generous of you to make your plans available. I had initially planned on building a JGRO, but Joe's seemed a bit more substantial. My Build does have some minor mods to it. I decided to make the cutting bed as long as possible. Also most of the assemblies I have dadoed together, to help all the pieces lock together, as well as increase the various gluing surfaces. So here's a quick breakdown:

-Joe's CNC:
-72" Cutting bed
-Acme leadscrew, 1/2" -8, 2 start
-Dumpster Cnc Anti-Backlash Nuts
-Keling 425 in/oz stepper kit w/ ps, drivers & breakout board

I think those are the pertinent facts. Most of the hardware is ordered and should be getting here soon. I have a stack of parts cut and hope to start assembling soon, as I'm building without a CNC most of my parts do not have all of the various holes cut, I plan on doing several alignment assemblies to get all the bearings and rails aligned so they don't bind at the end of travel. Thats pretty much it, I hope to be able to learn from anyone here willing to to advise. Let me also apologize if some of my questions are profoundly stupid, this is all new territory for me, that being said:

-My head spins when I try to learn about software, there seem to be a lot of options, I'm looking for something free, (don't know how many options that leaves me) I want to be able to cut archtop guitar bodies, guitar necks, ski cores, etc, things that require some relief cutting.

-I have read that resonance is an issue on some machines. I'm worries about this because of my longer X-axis. Have read about preloading the leadscrew, does this require a thrust bearing for long term wear? I've also read about putting another bearing on the carriage near the backlash nut. Should this be a nylon or delrin flange bearing? it seems to me another metal sealed bearing in a location like that would cause trouble?

-I'm planning on dedicating my old computer to drive my machine. AMD socket 939? 1.6ghz?, 4 GB ram. I'm comfortable that the hardware should run the software, should I go into the bios and turn off all but the most basic functions to improve latency?

-Limit switches. Initially I thought to wire two per axis in series. On further thought it seems to make sense to wire two per axis ALL in series, so all movement stops when a limit is reached? Is this to simplistic, will the driver board stop all movement from one input anyway? Is there I good thread on this I could check out, have not had much luck searching that speaks to my level (ignorance). Also home switches.

-I bought a drag chain to keep things clean, I think its like 1 1/2" x 1/2", Is shielding a big concern? It just seems that getting shielded wire bundled per motor will eat a lot of space quickly. Also should I rout the AC for the Spindle separately?

O.K sorry, too much I know, any help is greatly appreciated, I'll try to post some pics. Thanks in advance!

[ger21]

I can tell you that those screws will whip badly at that length, unless you can apply a lot of tension to them. To put them in tension, you'll need thrust bearings at both ends. Not plastic bearings.
I use the same screw, but 60" long, for 45" of travel, and the whipping limits my speeds to 150ipm, or about 600rpm.

Resonance isn't really related to the length of screw. It has more to due with the drives your using, and the particular machine. I don't think there's any way to determine if you'll see it until you start using the machine.

This is probably the best source of info if you're looking for free software.
cnc4free.org homepage

There's no need to shield the motor wires, but it can help with the wires for the limit switches.

[Ohioflyer]

Some Pics

[Ohioflyer]

Thanks Gerry, The plastic Bearing was an idea for a mid-thread bearing, one that travels with the carriage, very near the backlash nut, I don't think the plans have any, the reason for plastic is because it would need to slide along the length of the leadscrew. The end bearings would be rollerbearings of course, but now I'm thinking thrust bearings...

[louieatienza]

Hello All,

I thought I had better start posting as I am sure I will probably have lots of questions soon. Let me start off by saying that I have never done any CNC work before. I am a woodworker by trade and by hobby and have always wanted a CNC machine. I have also done quite a bit of electrical work, both AC and DC. The AC side is where I'm most confy, though I I have done electronics assembly as well so a soldering iron and small guages don't bother me. Really what I'm saying is that I hope these skills will get me up and running with my own CNC!
As per the title of this thread I'm building a Joe's 2006-R2. Right off the bat let me say Thanks Joe! Very generous of you to make your plans available. I had initially planned on building a JGRO, but Joe's seemed a bit more substantial. My Build does have some minor mods to it. I decided to make the cutting bed as long as possible. Also most of the assemblies I have dadoed together, to help all the pieces lock together, as well as increase the various gluing surfaces. So here's a quick breakdown:

-Joe's CNC:
-72" Cutting bed
-Acme leadscrew, 1/2" -8, 2 start
-Dumpster Cnc Anti-Backlash Nuts
-Keling 425 in/oz stepper kit w/ ps, drivers & breakout board

I think those are the pertinent facts. Most of the hardware is ordered and should be getting here soon. I have a stack of parts cut and hope to start assembling soon, as I'm building without a CNC most of my parts do not have all of the various holes cut, I plan on doing several alignment assemblies to get all the bearings and rails aligned so they don't bind at the end of travel. Thats pretty much it, I hope to be able to learn from anyone here willing to to advise. Let me also apologize if some of my questions are profoundly stupid, this is all new territory for me, that being said:

-My head spins when I try to learn about software, there seem to be a lot of options, I'm looking for something free, (don't know how many options that leaves me) I want to be able to cut archtop guitar bodies, guitar necks, ski cores, etc, things that require some relief cutting.

-I have read that resonance is an issue on some machines. I'm worries about this because of my longer X-axis. Have read about preloading the leadscrew, does this require a thrust bearing for long term wear? I've also read about putting another bearing on the carriage near the backlash nut. Should this be a nylon or delrin flange bearing? it seems to me another metal sealed bearing in a location like that would cause trouble?

-I'm planning on dedicating my old computer to drive my machine. AMD socket 939? 1.6ghz?, 4 GB ram. I'm comfortable that the hardware should run the software, should I go into the bios and turn off all but the most basic functions to improve latency?

-Limit switches. Initially I thought to wire two per axis in series. On further thought it seems to make sense to wire two per axis ALL in series, so all movement stops when a limit is reached? Is this to simplistic, will the driver board stop all movement from one input anyway? Is there I good thread on this I could check out, have not had much luck searching that speaks to my level (ignorance). Also home switches.

-I bought a drag chain to keep things clean, I think its like 1 1/2" x 1/2", Is shielding a big concern? It just seems that getting shielded wire bundled per motor will eat a lot of space quickly. Also should I rout the AC for the Spindle separately?

O.K sorry, too much I know, any help is greatly appreciated, I'll try to post some pics. Thanks in advance!

It will be tough to find CNC software that's free AND does 3D. FreeMill does it but it's very limited. CNC Toolkit is powerful, but there is a steep learning curve, and you need 3D Studio MAX (which is NOT free!) MeshCAM and CamBam are both pretty powerful for the price, though CamBam might be more versatile. HeeksCNC is free, though I've never tried it. This is probably one are where you get what you pay for.

Maybe not the length of your screw per se, but whipping from the screw could cause your motors to stall. You may need to add additional reinforcment to your frame to tension the screw. The thing is, the screw may heat up with long use, so much so that you may lose the tension you put on it. Maybe belleville washers or such could keep constant tension on the screw. There also is what is called mid band resonance. Maybe somewhere around the 300-500rpm range. You can overcome this with dampers, electronically (with a GeckoDrive); otherwise it will limit your rapids speed. A way around this would be to use a higher lead screw (5-start or even 8-start) so that you can gain speed without having the motor spin excessively. This might necessitate a slightly larger motor for the x, though I run 425in-oz steppers with only 24v power supply and I move my gantry with 8-start leadscrews, and my gantry weighs over 75 pounds.

I would check with the Mach site. Not sure if AMD is compatible?

[Ohioflyer]

Thanks for the reply Louie,

Have not heard of a bellville washer, but I can envision some sort of tension block to support a bearing to apply constant pressure.
Does anyone run Linux CNC? I've run Linux for years, the only thing is that my current uses are not that critical. If I'm watching my media center and there's a hiccup its not really a problem. I imagine if I was carving on an expesive piece of burl and that happened I would be a little upset.
I finally sat down and checked out the breadboard wiring diagram, limit switch questions answered. Sill would like to learn more about home switches, can anyone point me to a good thread?

[PaulRowntree]

Here is a good thread on switches.
Electronic home switches made easy!
Cheers!

[Deep Groove]

Thanks for the reply Louie,

Have not heard of a bellville washer, but I can envision some sort of tension block to support a bearing to apply constant pressure.
Does anyone run Linux CNC? I've run Linux for years, the only thing is that my current uses are not that critical. If I'm watching my media center and there's a hiccup its not really a problem. I imagine if I was carving on an expesive piece of burl and that happened I would be a little upset.
I finally sat down and checked out the breadboard wiring diagram, limit switch questions answered. Sill would like to learn more about home switches, can anyone point me to a good thread?

Check your distro - you probably already have EMC2 on hand. Probably the most-used linux CNC software.

[PaulRowntree]

Check your distro - you probably already have EMC2 on hand. Probably the most-used linux CNC software.

Yes, but I believe it needs the Real Time kernel modification. When in doubt, go to the source ...
Download Information
Cheers!

[CarveOne]

Go to LinuxCNC.org and download the EMC2/Ubuntu Linux ISO file from there. That version of Ubuntu has the realtime kernel modification and other changes specifically for EMC2. You can't run EMC2 from just any distro of Linux.

It will let you try it without installing it to test your computer hardware compatibility, then install it.

CarveOne

[roy_okc]

Does anyone run Linux CNC? I've run Linux for years, the only thing is that my current uses are not that critical.

(Also a long time Linux user) I've been using EMC2 since completing my build last summer. It took a bit to figure out a few things in the config files (dual X steppers, understanding and dialing in speed and acceleration, etc.), but once I got it set it has worked great for me. Due to a early P4 CPU, I'm limited to 100 IPM on Y and Z and 150 IPM on X; however that is plenty fast for the small projects I'm currently working on my mid-size build. I will likely upgrade my inside system later this spring and probably put the current MB, CPU (AMD 5000+), RAM on the CNC.

Good luck,
Roy

[CarveOne]

I ran my first CNC machine with EMC2 (and still have it) but the Ubuntu is the 8.04 LT release. Hopefully, they have made it easier to configure the slaving settings in the later releases. There was only spotty info about it a couple of years ago. I did figure it out eventually, and have a G540 configuration for EMC2 that does that.

CarveOne