CNC resumes!

Machine Move, Ballscrew setup

I'm back! I have been so busy with school, internships, work, that until now I've been full up to my ears with stuff! I'm interning for a major northwest manufacturer making metal parts.

Troy's brother has a great shop, and is kind enough to let us work there on our CNC project. I moved all the components out of my room to there! What a relief! My room no longer smells like gear grease!

So at this stage the controller board is working with the 3 stepper motors, and the computer. The same day that we moved the stuff there we bought some shelves and put them in place to keep all the equipment. We spent that time building installing the shelves.

Another week we came in and worked on assembling the ballscrews. They were a really tight fit, the ballscrews were purchased on ebay custom cut to our size. So we were saving money by doing this. Unfortunately, the ballscrew blocks, that hold the bearings were not sized perfectly, they were an interference fit. So we tried heating the blocks with a torch lightly. We found that didn't work that well at all. What did work was forcing them on with force, and properly aligned pressure. So that is what we did.

We had to bore out the insides of the motor mounts as they didn't quite fit on the s

haft, Troy was able to quickly take care of that on his harbor freight lathe. (Paying attention not to break a v-belt.)

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Motor Wiring

Today grant came to work on the machine with us too. He rewired the motors to utilize RJ-45 we have concerns that the wires are not thick enough to carry the current. We looked it up, they have a max spec based on 24AWG of 3.5 AMPS per individual strand. Our motors in unipolar mode will be running at 2 Amps. Our voltage is something like 24 volts? not sure, i'll have to check that later. I'm concerned

that the limiting factor is not just current but power over the line. So we will have to double check that

later.

Troy traded some equipment and acquired a ton of aluminum extrusion, that should work great for a frame. This means we will have to source some connector plates, and design them as well.

Troy quickly worked up a new control board mounting strategy with the motherboard mounting kit I found. He cut, and drill/tapped aluminum scrap to make the mounts. He also he-manned one of the brass screws, and broke it off in the hole, so he had to re-drill and tap to fix it.

If we are good we will need to:

* Purchase Female RJ45 connectors so we ca

n easily disconnect the motors from the control board. (If rj-45 is ok for our CNC motor power)

* Consider shielding options for the motor wires.

* Finish mounting the control board

* Model the frame again with the new extrusions troy got.

* Install limit switches

* Bring more RJ-45 cable for limit switches.

* Explore spindle options

These are the ends, that would be nice to have rj-45 connectors on them. It is easy to pull out a motor's wires at the control board. We also cut and drilled some simple aluminum angle iron to act as a heatsink on the drives. A quick run to the store and we had the right fasteners.

CNC Plasma, and potential laser cutting/plasma projects

Cool Stuff in Numerical Control Programming Class

I've been assigned to come up with some maintenance documentation for the Plasma CNC we have at our school. It is obvious that it isn't used much. The documentation for the torchmate 2 system is nicely done. I believe it was a previous senior project from a kit, and it's obvious the students did a wonderful job setting it up.

Today, I had the opportunity to start the machine up (after carefully reading the documentation) and jog the x and y axis around. I'd like to measure the kerf sometime soon to document that.

I eventually will need to come up with a sample part that my professor will be able to easily demo to prospective students. So i'm trying to come up with ideas for that. Here are some neat links with great ideas and source files:

http://www.cnczone.com/forums/showthread.php?t=5276

http://www.cnczone.com/forums/showthread.php?t=19346

In my research about the CNC plasma cutters I've stumbled across a wealth of resources that I wish I had time to dive into right now.
http://www.cncinformation.com/advanced-robotic-tech-cnc-plasma-cutter-videos/

which has a variety of videos talking about CNC plasma cutting.

I signed up for a yahoo group where I was able to find a majority of these resources from:
http://tech.groups.yahoo.com/group/plasmacutting/

Getting involved

Whether it is a detrimental thing or not I'm getting involved in two more clubs at my school.

• Mars Reach
• Society of Manufacturing Engineers

The mars reach club does high altitude balloons, rocketry, and a few other things. SME may let me do some community service with some of the engineering knowledge i'm learning at some local schools. Which actually sounds cool to me. I always loved teaching children at OMSI, and cybercamps.

I've been researching high altitude balloons for taking atmospheric pictures like the one below(100,000 feet.) I am very excited about it. I am timid to commit too much time though as I have plenty of schoolwork and other projects going on at the same time. I just made a personal decision not to let good opportunities pass me by. "Reach for the stars" so to speak.



Image from http://www.natrium42.com/halo/flight2/#hardware

Here is some of the fruits of my research:

1. http://vpizza.org/~jmeehan/balloon/
2. http://www.universetoday.com/2006/01/20/satellites-on-a-budget-high-altitude-balloons/
3. http://hackaday.com/2009/09/19/high-altitude-balloons/
4. http://www.natrium42.com/halo/flight2/#hardware
   
5. http://www.arhab.org/

On a seperate topic - i stumbled into this engineered nerf gun esque thing. http://boltsniper.com/BS-5/BS5.htm pretty slick. He calls it a FAST-ACTION RIFLE(FAR).

So for now I'm just going to try and stay on top of things, as they just keep piling up, and i keep knocking em down at about the same rate. Kind of a good and bad thing. *shrug* at least it's progress. Onward!

Schoolwork update

I've been busy with school specifically ethics and micro-economics as they have been assigning nearly daily assignments of varying difficulty. While this is all going on we did a neat lab in Numeric Control Programming a week or two ago. The pictures show what i was able to accomplish with hand coding some g-code. I was limited because of time, and I wanted to do a much more elegant part, but had to settle for this.

Troy sent me the spindle model. I've been working on a similar part for our numeric control programming class as well, which i finished coding today. It was much more involved that the previous as i had to code in the rough and finishing pass, there was a lot of math involved to ensure clearance distances for the part were appropriate. Either way the lab assignment will help fabricating the spindle for the CNC machine that much easier.

Here's what the CNC lathe simulation for my Lab looks like:

Research of various CNC machine/gantries

This guy has a similar build to ours. I'll be supplementing this list as i continue my research.

http://www.cnczone.com/forums/showthread.php?t=27527
What's interesting is he also is using 80/20 extrusion, ballscrews, and 425 oz-in steppers. His is a router build, so we have the complicating element of the head design. I don't know what i'm going to do about the Z-axis still. He also mentioned his z-axis having trouble lifting the 28 pounds, i'll have to look into that more, and consider it for our head design. Interestingly for a home switch, he uses a .25" thick piece of aluminum with current to arc current through and accurately determine if the head is @ zero.

More to come...

Spring Design

I recently have been discussing spring design with a fellow named Shredder. While I did this last year I was able to apply some of the concepts i've learned from Machine Design II.

http://www.airsoftretreat.com/forums/index.php?topic=82508.msg808447#msg808447

There are some screenshots of what i was able to do with the data. I'd like to verify the forces with weights to see what force the springs are generating so i can correlate it to the theoretical force generated based on the spring geometry. I'm sure it's off - i just don't know by how much.

Shredder wants to make a 1000 fps airsoft rifle. So naturally increasing spring force is a good place to start. I was inquirying how he made some of his springs and learned that i may be able to do it too!

Here's the reference information:
http://shredderscs.proboards.com/index.cgi?board=projects&action=display&thread=80&page=1
http://home.earthlink.net/~bazillion/tooling.html
http://home.earthlink.net/~bazillion/Coiler/index.html
http://home.earthlink.net/~bazillion/compression.html#tweaks

While researching spring mfg processes, I ran into this useful fellow who seems to be adept at metalworking. He also has some useful tube cutting techniques could be useful for HPV.
http://metalgeek.com/

Focus shifting back to the CNC

With daily homework from ethics and micro-econ keeping me at bay, I have little time to focus on the classes i really want to pour my heart into - CNC class and manufacturing planning.

I am shifting my extra-curricular focus back to completing the CNC machine. There are two major issues to tackle at this point:

-Research, and Redesign frame for rigidity (likely a Gantry setup build)
-Consider, select, and integrate head design (we don't know whether we will build troy's spindle or buy an aftermarket solution)

I previously was concerned with opto-isolation, but after this forum post on cnczone I'm not as concerned with it. I will do what is called common grounding/bonding which is as described in the thread involves using the same ground for both the computer and stepper powersupply circuit. It is rumored that this helps remove noise interference issues by making both the same potential. http://members.cox.net/pc-usa/station/ground3.htm


I'm doing research on the various gantry configurations others are using and considering ballscrew/rail placement. The technical difficulty i'm facing is that we selected such a large z-axis. This means it may look like a tower when it's done... Hmm more on this as i find things out.

http://8020cnc.com/cnc%20pics

Back to homework!

Another quick project

My professor was telling me how he needed to make a projector mount, so I decided to jump on the project. I must be getting more proficient at SW because here's what I got after about 2 hours of work. I put some gaps underneath to allow the projector to breath. The actuating device is simply two bolts, I didn't model them. Although, I hardly think that is necessary to convey the design concept. Some specifics aren't on the model, but can be easily added (the bolt pattern for the bottom of the projector.)

It was fun. Time for sleep.

Low cost Laser engraver

My friend bryan found this little gem.

http://www.instructables.com/id/60-Laser-Engraver--Cutter/

The guide shows how to make a pantograph; which is a device that lets you mimic hand movements in 2D exactly using a mechanical device. Kinda cool, i wonder what other applications they could have.

There is rumor that you could hook the laser up in place of the ink-cartridge, and turn a printer into a laser engraver/cutter. Frankly, I don't think it will be powerful enough for good work. I'd probably go with a 60 Watt CO2 laser if i was to build one myself.

Very cool nonetheless.

By the way nasa is cool :) Perhaps some future CNC projects...
http://www.nasa.gov/multimedia/3d_resources/3d-models-gallery.html

Waterproofing electronics

I was doing some research on solenoids for a new"ish" project, (more just exploring possible future projects) and I stumbled across a bit on waterproofing servos for robotics. Now this is marginally interesting except that I'm sure that the methods they are using would apply to other electronics.

http://www.societyofrobots.com/actuators_waterproof_servo.shtml

I'm thinking about waterproofing my ipod nano for swimming. Liquid Tape sounds like a possibility... Anyways, rest time.