I have been mulling over ideas on how to design this cnc. Mainly I have found 3 design plan sets which seem common online yet none of them meet my needs. Since I am incredibly picky about this sort of thing I figure the best thing to do is to take bits and pieces from different places and make something which is uniquely mine.

Joe’s CNC ( http://www.joescnc.com ) – He has 2 different designs. The first one was made in 2006 and is one of the standards that you see people on cnc forums talking about. His plans are free and it seems like a solid unit. The issue I have with it is that it is a full wrap carriage; meaning that the gantry travels under the work surface. This is bad for a number of reasons but mainly I got a super table to mount this on, namely the new Biesemeyer Extension table for the unisaw ( I wonder how I got that ) and that would prevent this design from going forward.  The second design from Joe is much better but I refuse to pay 100 bucks just for the plans for something I can design myself, I am not really into just building

The next set of plans is the JGRO Plans Like Joe’s plans it offers simple construction methods with MDF and some of the same features. If I was a betting man (which I am) i would say that one of these 2 sets of plans inspired the other. Full plans are available for this one for free, but I really dislike the way that he does linear motion. There is no way I can tell to hold reasonable accuracy with out really spending time tweaking the unit after assembly, something that I know is likely no matter which way I go.

The last type is from the site www.buildyourcnc.com  he has 2 different designs and the one I am going to make  most closely resembles his new machine the black toe while I don’t understand the name I really like the way his linear guides are done.

So the project starts, I purchased these v-bearings for a cheap price of 2.50 each and as I continue to spec my machine I will buy the parts which will help me create more cool projects in the future.

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1)  A simple mechanical drive where I power the rear wheels and have casters on the front. This use of differential steering will be sufficient for my needs, but it doesn’t have that flare which makes a project stand out. On the other hand doing something simple (KISS FTW) may take the time required to finish the project more achievable.

2) My next thought is a mechanically more sophisticated system of using mecanum wheels on the robot.  Mecanum wheels are ones that allow for holonomic movement(movement in any direction) You can read more about them here http://en.wikipedia.org/wiki/Mecanum_wheel   One of issues with mecanum wheels is that they need to ensure contact with the ground at all time to work, which is why they are traditionally used in systems which roll on flat floors such as forktrucks. In the uneven ground of a yard or offroad the robot would require a suspension system, which is where the complexity begins.  Normally suspensions are straight forward because their only requirement is to keep traction and keeping close to the ground is not a factor like it is when mowing the lawn.  In the research I have done so far I have yet to find any off-road mecanum robots, in fact the closest I found is a concept for a mars surface vehicle. If I do go this route I plan on using the mecanum wheels from Andymark, as they offer 6inch,  8inch, and 10inch options with different modular hubs, which will make the challenge the implementation of the system not re-inventing the wheel.

This is the first paint style sketch of what I am thinking about if I decide to go down the mecanum path. Obviously the largest challenge is to keep the blade at a constant height so that I still have a good cut quality in addition to a autonomous robot cutting it.

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Here are a beginning list of things I AM going to work on.

• Coaxial Swerve drive – my team wants to build one and convert the robot for IRI. I am waiting for the kids to start being proactive about this;as I am going to guide them, not design it for them.
• Robotic lawn mower – Last year my boss gave me a black & decker electric lawn mower. Cutting my lawn is up there as a thing I don’t want to do so it makes sense. I will design and build a chassis for it and start by converting it to RC then add sensors and other goodness as time goes on.
• CNC router – I have been interested in CNC for some time now and no matter how many times I have had things made for me I still don’t have much experience with it myself. So the net is filled with plans and ideas on DIY cnc stuff so building one for my garage would be fun, IMO.
• Underwater ROV – I have never done an underwater robot before and think it could be fun. We have this sketchy pond infront of work which seems prime to stick a robot in and explore. Also the cost factor with this one is low which makes it ideal for my garage.

I think that’s a good start. Also with these projects I am going to start developing the robot webcast show Botcentric I started on last year, these 3 things seems to be a good idea for a few episodes.  As always I am going to post project updates to this site, twitter, facebook, and any other tool a stalker could use to find out what I am doing. So if you don’t see updates poke me because that means I have either gotten lazy about the projects or am sucking at documentation.

Greg

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video on gizmodo.

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here is my new camera a canon HV-20. It shoots 1080i HD onto mini dv tapes and should make my videocast have really good quality

In other news my life has been on an even kilter for a while now which for me is a nice change. I have started to settle into my own skin a bit more and am now able to do the things I want to do.

I have also registered for a motorcycle class and will be getting my license this month. A motorcycle purchase is in my future.

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I will be doing these in instructables.com format as step by step instructions. Look for them soon. Some topics will include:

Effective use of CAD for robot design

How to decide which, and design your robot drive train

How to install xp over vista for OEM computers

etc….

There was also some talk a few months ago with some of the guys from www.thebluealliance.net about turning some of these into video tutorials. If that happens it won’t be till much later in the summer.

For now sitback and enjoy this dancing robo known as keepon.

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So in response to my twitter post I got many messages about why I will never buy from newegg.com again so here is my story.

I have been looking for the past month or so for a new desktop computer. I was looking for an inexpensive quad-core machine mainly for CAD, but more importantly to last for a while. I had been finding these refurbished computers which had really good specs and we inexpensive, but I still wasn’t sure yet. Well about a week ago my desktop decided to die which really forced the issue. I looked things over and decided on this system. http://www.newegg.com/Product/Product.aspx?Item=N82E16883113052 A few things that sucked for me was that I live in TN so I had to pay tax but I was still saving like $50+ from other vendors.

So I place the order and everything goes smooth I get the machine today. Well the first thing I did when I took it out of the box was do an inventory in order to be sure that everything was there. So I find that my windows media PC remote control and a s-video to composite adapter are missing. So I figure no big deal I will call newegg and they will take care of it. Now here is where the fun begins.

I get on the phone with a customer service representative named Marie and explain my problem to her. She then goes on to tell me that for refurbished products they don’t guarantee any of the accessories that may come with the machine. WHAT!? so basically newegg can advertise that you are going to get all these great things with the computer, but never actually deliver the product? This really gets me upset because in a machine which costs 700 a remote control (while not important to the function of the machine but a nice to have accessory) which would normally cost about 40 bucks factors into my value of the system I am purchasing. There were a bunch of other machines which were close in specs but this one added up to be the best value.

So we go back and forth about false advertising and how if it says something on their website in the product description that they should deliver. I mean how would you feel if you bought a car with a cd/mp3 player and then on delivery was told “sorry we don’t guarantee accessories so you don’t get any radio” ummm hello?! is anyone alive in Newegg thinking land, what the hell kind of policy is this. She even agreed with me that she would be upset if something she purchased was not as advertised. Anyway she offered me a $25 credit back on my account; which is a nice gesture but it still doesn’t address the real issue of their backwards policy and false advertising.

I ask for her manager at this point and get the response ” I will get the manager but he will need to know what you want as a result” hmmmmm…let me think I want what I paid for! come on woman use that muscle in between your ears. So she puts me on hold for 10 mins and when that time is up she picks up the phone again. Basically the manager won’t talk to me so she is going to relay information to me. Their compromise is one of the best parts of this story. Now on referb machines newegg has a no-refund policy (they have alot of these policy things) so they decided to “make an exception in this case and allow me to RMA the machine minus the restocking fee of 15%” Are they freaking serious? do they really think I am going to return this machine only to loose more value than the item I wanted replaced. What the hell are they smoking to come up with that as my exception.

At this point I have been on the phone for 45+ mins and I have just about had enough. With Marie on the phone I tell her I am going to do 3 things. 1) I want her name 2) I want the $25 credit and 3) I want her to check out blogs later because I am going to talk about my experience.

Basically for me this isn’t about the remote, but it is more of the principal of the thing. I know it seems like a whole lot of trouble for a minor thing, yet I am not happy with the outcome. It doesn’t seem right for one of the leading online retailers to put someone in a big fuss over a 40 product. Also as a responsible reseller when they put something on their site for sale it should be what customers get when they place an order. This kind of negligence is not forgivable in a marketplace where there is lots of competition and the main thing that separates stores is how they handle their customers.

I have a letter drafted that I am going to send to their CEO, to express my feelings as I have found that many times upper management at large companies are totally disconnected from the real issues at hand. If nothing else comes of this I just wanted people to know my feelings and as far as I am concerned I am not going to look to newegg for any future products, because hell who wants to take a gamble that they may or may not get what they purchase.

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