Well, It’s been three years at Rejent (plus a week). Since I haven’t updated in a while I figured I’d go through some of my Solidworks files and post a few of the things I’ve worked on during my time here. After looking through the files I am quite amazed at how freakin’ many parts I’ve worked on over the time I’ve been here. Hundreds of different things!
Anyways, here are some pics of a few things I’ve worked on during my time here, albeit a very limited selection of them.
That was just a few of them that I randomly found, nothing too crazy since some of I couldn’t really show. Well, let’s see what the next few years brings.
I have just finished the project that has taken up the last 3 months. Delivered to the customer and they are very happy with it.
I’m so glad to be done this project. While it wasn’t a terribly long project, I’m glad it all went off without any real problems. It measures better than they’d hoped and it’s a pretty attractive little package, for what it is. Next iterations will be significantly smaller and I will look at new encoders to use.
Also, as an aside I have set up my new office. It’s nice to get out of the basement. I now have a lot of free room now so it’s nice to spread out and be able to sort through all my shit and set it up as efficiently (for me) as possible.
This device is almost complete. Yes, It’s missing its buttons but the device seems to work well and nice and smooth. The real anvils are almost done and the device will ship to our customer fairly soon and I’m glad to see these guys be done!
There are still some tweaks to make especially in the realm of overall rigidity but overall it’ll be a neat device to attempt to bring to market in different ways.
Well, it’s coming along with some speed. I am now going to build the final version complete with internal battery charging, better logic and a severe reduction in mass. Hopefully this will go down well with the customer.
Anyways, this post was for posterity. As always I hope it turns out well. 🙂
Something I haven’t worked on in a while but is coming up is my new electrolytic deburring machine. I figured I’d post a couple of pictures for posterity.
In it’s current state, it does work to a degree. I need to work on the chemistry of the fluid. Right now it seems to just pit the material. Perhaps the voltage is too low or too high but I suspect it’s purely a lack of conductivity or the incorrect chemistry for this type application.
Eventually we should be able to deburr cutters and various other items. Just thought I’d share.
It’s been a while since I’ve posted and that’s primarily because I’ve been working on a project. I have to keep some of the details to myself but I will show some pictures of the prototype that has taken me a couple of weeks to design and build.
The device uses the AT715 from Mitutoyo and what an interesting device it is. With a resolution of .0005mm and an RS485 interface, it is an ideal device for measurement and for use on machines. The device, which uses magnetic induction, uses 30ma whereas a lot of other glass scales use up to 250ma @ 5v. This is a pretty cool device.
Well, I can’t get into a great deal of detail because the product I have in mind may compete with other gaging companies like Gagemaker with a universal, handheld, high precision, digital gage that has active, rugged and dynamic probes. The images shown are that of a rough prototype, I’m not normally secretive but once one is built in a few weeks I can post some images of the more refined version.
Having needed an adjustable power supply with a bit more current, I decided to buy this guy for about $140 off Ebay. I’ve played around with it a bit and I decided to review it because I’m sure there are a lot of people like me who buy cheap test equipment. You don’t pay much and you can’t expect much, but you can just hope it does the job.
I performed a few tests that you can see below:
So, if you looked at the values shown, you’ll see it works OK. Anyways, here are some pros and cons to this device.
Knobs and switched feel good
Nice high current for a unit like this
Nice grill effect over the LED’s make it look like a dot matrix LED
Standard size case
LOUD LOUD LOUD! Not quite vacuum cleaner loud but louder than anything else in my office.
Front power connectors are kind of flimsy and cheap
Displayed and measured values do not quite jive
Does not have a handle on the top, it’s nice to have a handle on test equipment
Otherwise, the unit works as expected and I’ll write the LED flicker off as a coincedence. It’s too bad that it’s so loud, they could’ve used a different fan or something, becomes a real distraction. If you need something like this that produces 30V at 10A, this may be good purchase.
A few weeks back I got my Mercury FPGA unit and what a nice little unit it is. The device plugs directly into a breadboard and could potentially be used as a drop-in for through hole PCB projects. When I got the unit I was impressed with it’s overall appearance, they sure packed this guy tight.
Having played with this a bit I can see the usefulness of this device. Here are some of the features.
A Xilinx XC3S200A-4VQG100C running with a 50Mhz oscillator
Complete with proper voltage regulation @ 1.2v and 3.3v
Some 5V tolerant IO pins
A USB port for direct programming and power from the USB port
A separate ADC with 8 channels linked to the FPGA
A couple of switches and a few indicator LED’s
You can program through the JTAG interface
You can use the Xilinx ISE design tool to synthesize the project and you can use the Mercury software to upload it to the unit. Just based on the little bit I played with it, it seems to be a very useful unit. It’s great for learning (like I am to a degree) and is well designed and labeled on the PCB. There aren’t a lot of bad things I can say about this device except a couple of minor issues.
Issue one would be the sheer size of it. The unit fits on the bread board but with only one spot left on each side to connect things. This is a very minor issue and they did a good job making it as small as it is with as many pins and size of chips it does have, but having only one remaining pin could be an issue.
Issue two is its price. At $65 USD it’s a but more expensive than some other units out there. That said, they are unique in their pcb profile and the developers have to get paid for their time. My serial number was 147 so with such small batches, it’d be difficult to lower the price point. Hopefully it becomes wildly popular and the price can come down to a point where it can be considered a consumable of sorts.
Anyways, aside from my very minor complaints, this device is pretty cool. I can see all kinds of projects benefiting from a DIP style FPGA unit unlike the others which seem to have an arduino style PCB that makes it difficult to include in a project. I recommend that anyone who is going to learn FPGA’s give the Mercury a shot.
I decided to try out my new Hantek DS1060 and get some waveforms from the head of the EDM (Electrical Discharge Machine). The probe was hooked to the head of the machine and the ground was connected to the frame. I only took a few measurements but it may be interesting to some to see what the pulses look like when it’s cutting. This cut was burning at 75us on and 37us off.
You can see that the voltage doesn’t drop to zero, and there seems to be a dropoff after the ionization path has started to cut the material. These dropoffs after the spike seems to indicate that the path is ionized and current control has kicked in, providing 8 amps. Once the time is up, the current shuts off and then there is a ringing spike, perhaps due to inductance. From there the voltage doesn’t reach zero but probably sits at a continuity testing voltage for a little under the 37us. From what I can tell, 75us is started from when the ionization path is established, and 37us is the time it cuts off the current, event though there is still voltage (and maybe a bit of capacitiance).
The measurements seem to correlate to the settings a bit. The EDM itself is set for a 240V cutting voltage so the VMax of 181V is pretty close. I think those values are a quite flexible, I know that before it cuts at all, the voltage is at approximately 240VDC.
Anyways, I thought this would be interesting to post since some people are into EDM machines. I may take some waveforms from the wire EDM and two more different EDM’s. Here’s a final image of a zoomed in view of the peak.
I was thinking about cockroaches after seeing some sort of program on the subject. It brought me on to thinking about insect locomotion and the way complex moves are carried out by creatures without a central nervous system. It then started to occur to me that the reason that these creatures (or any other for that matter) function is that there are a great deal of stimuli. An insect’s leg, for instance, has thousands of sensory organs to determine touch, temperature an various other external events that aren’t processed anywhere centrally. The thought the occurred to me about the notion of how a nervous system might work. Hence my latest, yet ugly, creation. The Roboto v2.
I had a frame for a robot I had already assembled and really didn’t get anywhere with it until I had this idea. Basically the idea is to have a matrix of variables, in this case a 10×10 struct array. Sensors are ‘bound’ to certain segments of the matrix. The matrix elements also communicate with the adjacent nodes to relay positive or negative stimuli. These stimuli make their way to the motor controls which are bound to other matrix nodes, in my case, elements several nodes away on opposite sides of the grid. The values expressed in the node are translated into motor movement.
What I have right now is functioning better than I hoped. I made close proximity ‘painful’ and moving forward ‘pleasurable’. A close proximity on the side will cause pain on the same side. Currently the robot seems to find open areas but doesn’t stay in them. I did fudge some things which are.
Output to the motors is kind of jury-rigged to disallow stopping by ensuring that at least one wheel is at maximum motion based on a weighted average.
the sensory input is weighted at the nodes. This was needed simply to make it function correctly.
I have a constant ‘pleasure’ value plugged in to make the robot strive to move forward. otherwise it would probably just stay in one place.
Here’s a video of it in action, doesn’t do a lot but I think it’s neat because I can’t predict it’s reaction despite the fact that it’s perfectly logical.
Well, I’m going to try some other things and add more stimuli like IR sensors, compass, accelerometer and a gyro. We’ll see if I can get something interesting out of it. An in case anyone is wondering about the build here’s a point by point list of what I used.
A robot chassis that I bought off EBay. It’s not bad.
Built the motor driver board myself with an SN75441one and a 5A linear LDO reg.
7.4v LiPo battery, 850mah for direct drive to the motors
A little cheap bread board
and LED-KEY module, based off the TM1638, very handy modules