Looks like a valve build might be able to happen this weekend! We are pumped to get the Ion firing more effectively. As long as I can get to work on some design we should be able to turn it out this coming weekend!
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With our last build resulting in a gun that could be muzzle loaded to fire single shots, Brian was confident that we could attain semi-auto firing over the course of the coming weekend. The main problems and parts that needed to be addressed to get to that point were correcting the cycling issues in the bolt, rigging a sort of makeshift trigger system to fire the gun, and feeding paintballs into the system.
The issue that had to be solved first was the issue of cycling. After our second build, we found that the bolt was not being forced forward by the firing pressure when the control pressure was released. To fire the gun, we had to assist the bolt by pushing on the back of it with something. We expected that the primary cause of this problematic friction was the surface finish of our internal parts. This appeared to be an easy fix after some fine grit sanding on the lathe. Another way that we helped the movement of the bolt was by deepening the o-ring grooves to relieve a little pressure on the bolt.
After these two fixes, the bolt started to cycle the way it was intended. In order to achieve semi-automatic dryfiring, we had to rig up a hose system to imitate our future trigger. This is roughly what we came up with…
In this setup, pressure is supplied by separate hoses. The firing pressure is constant as it will be on the final version, and an air gun is used to dump pressure from the control chamber in place of a solenoid-actuated valve. We did have a problem off the start because the trigger pressure input was pumping air too fast for the air gun to dump it. this was causing the chamber to remain at too high a pressure for the bolt to cycle. to fix this, we basically jammed a plug into the input hose to slow the rate at which air could flow through it just enough to allow the bolt to cycle. With this setup, we achieved semiautomatic fire without ammunition.
At this point I am returning to this post after over a year of absence, so my recollection may be a bit fuzzy. I apologize for any inconvenience.
In order to feed paintballs into the gun, we decided to create a basic hopper feed system by boring a large hole in the top of the gun. We then threaded the hole and created another piece that fit tightly onto the neck of a hopper and threaded into place on the gun.
Since this was the first time we had to do anything on a different axis than the firing axis, it meant we got to use a new toy. Brian had recently bought a four jaw chuck that was useful for this type of operation. The mount for this job is pictured below. The hole was started using a wood bore bit, and the hole was widened using a boring bar.
After making both parts, we attached a hopper and voila! It is amazing how much that hopper makes it look like a gun.
We rigged up our makeshift trigger system (partially pictured above) and took it outside to try firing it a few times.
Now that the firing mechanism is operational, we need to set up a trigger mechanism. The primary phase of this process will be the design of the solenoid valve. A concept is shown below.
First: A cross-section of the valve Second: A full image of the valve hammer
This valve will be actuated like a solenoid. There will be a copper wire winding around the left end of the valve body which will pull the hammer back when charged.
In the rest state, pressure will be routed through the valve as such:
With the valve in its rest state, constant pressure is applied to both the control chamber and the firing chamber. Due to the pressure in the control chamber, the gun does not fire. Once the valve is actuated by an electric current through the solenoid, the air pressure will behave as such:
With the control pressure now dumped, the present firing pressure will be able to fire the weapon. After firing, the source pressure will return the hammer to its original position as soon as the solenoid is deactivated, allowing the recharge of the control chamber.
Hopefully with some refinements to this design, and a free weekend to build, Brian and I can get a real paintball gun together. We still have to deal with making the gun run on CO2, which brings in a whole host of regulation and expansion issues, but I think we are fairly close to a workable product.
I am sorry to anyone who was affected by my delay in posting this write-up, and I hope you enjoy its contents.
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I’m to the point where I feel like I’m ready to sell this mod to a few brave beta testers! The kit will include all of the components required to do the mod (custom PCB, programmed microcontroller, footswitch, resistors, etc.). You’ll need to be able to solder and connect wires to the DL4 PCB, as well as assemble the Smart Switch PCB.
Check out our shiny new website for more details.
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The most recent success in my ongoing RF-45 mill repair project is the fabrication of a new Y-Axis lead nut. The stock nut was apparently lost somewhere along the way during the attempted CNC conversion that I’m partially reversing, so I had to come up with a replacement.
My first thought at replacing the nut was to make a new one out of acetal plastic based on the method described at the Home Shop Machinist Forum. On second thought, I decided it would be much more practical to see if I could find a replacement part online. Like many of the chinese machine tools out there, this mill is one of many clones of an original design. In this case, the Rong-Fu 45 is the original, and my copy was produced by Penn Tools. Unfortunately, I was unable to find replacement parts through them, but Grizzly sells a similar mill along with replacement parts. I dug through the manual to find the part number, contacted Grizzly, and ordered the nut. Easy enough right?
Unfortunately, the importer of my mill chose to use 8 TPI leadscrews, while the Grizzly version uses 10 TPI leadscrews, so the nut didn’t work. I returned it to Grizzly, and set off on my original plan of making the nut from scratch.
I started by boring and splitting the acetal to fit the lead screw:
The RF-45 mill I purchased on craigslist a few months ago had some issues… In an attempt to convert the mill to CNC using an extremely oversized ballscrew, a previous owner had milled a pocket out of the bottom of the bed, leaving the material below the bottom of the center T slot uncomfortably thin. With the goal of restoring some of the bed’s original stiffness, I’ve fit a steel plate into the pocket. This post documents the process of machining the plate to fit the bed.
Here’s the bed as it stood before adding the plate:
The battery on my Nike Triax watch (WR0127-004) died a few months ago. I finally got around to fiddling with it, and was met with an unexpected lack of information online regarding the replacement procedure. Looking the watch over, it seemed fairly straightforward, just remove the four screws on the backplate and replace the battery.
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A few weeks ago, my Craigslist RSS feed returned a listing for a mill for $300 only a half hour from my house. It was an RF-45 clone that the seller described as a “project.” The RF-45 is a much more substantial mill than the X2 mini mill I currently have, so I was intrigued to say the least. After a bit of thought and contemplating if I had room in the garage, I decided to give it a shot and contact the seller to get some more info.
It turned out that the previous owner had begun a CNC conversion on it, and in the process had milled a large pocket under the table in an attempt to fit a much too large ballscrew on the X axis. The mill was disassembled, but all the stock leadscrews and handwheels were included, except for the Y axis acme nut. The seller had intended to finish the CNC conversion that the previous owner had so poorly started, but never got around to it since he already had another CNC set up in his garage. Fortunately, he held on to all the parts necessary to run the mill manually. I’m not quite ready to jump into the world of DIY CNC just yet :-).
All in all, it seemed like a pretty good deal, so I arranged to pick it up the next day. Now I had to figure out how to move it. 700 pounds of chinese cast iron doesn’t just jump in the back of a truck…
So almost a year ago now, my brother Brian and I decided to make a dotted eighth tap tempo feature available on a Line 6 DL4 that I use on my guitar rig. We used an Arduino platform to prototype the project. I have been successfully using the mod for about 8 months now. Check out these videos for more info:
Here’s the full source code for a standard Arduino or a standalone ATMega328 chip:
I noticed there was a bug in the original code I posted. I went through and parsed a lot of stuff down in my original source code but I apparently made some errors. This code is the original source code and it is fully functional! 🙂
(Read the rest of this post…)
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I’ve used the Zenith SL-5408 motion activated security light as a motion detector for my Bird Blaster. In version 1.0, I couldn’t get the detector to work off battery power, even though the whole circuit runs at 5V levels. Now that I’ve acquired a little more electronics equipment and knowledge, I thought I’d take another crack at powering the detector from a low voltage source.
I started this round of reverse engineering by drawing out the power supply circuit in Eagle, adding components until I had reached the point where regulated 5V was present in the circuit. At this point, I didn’t notice anything that I hadn’t noticed the last time around. It was fairly obvious where the 5V supply originated, and that the PIR and timing circuit only used the 5V supply. The schematic is shown below. The 22 pin connection shown on the right is the point where the chip on board processor (the brains of the motion detector) is soldered in at a right angle to the main circuit board.
I keep a pair of peafowl as pets. Peafowl (the male in particular) like to look at themselves in anything that’s reflective. They also like to eat potted plants. This leads to a lot of peacock poop and damaged plants on our porch, which leads to me being in trouble with my wife :). Being an engineer, I figured the only reasonable solution would be to make a motion activated sprinkler to discourage them from hanging out near the house.
This was my first real electronics project, starting in the fall of 2011. My plan was to use a motion activated security light, a sprinkler valve from an automatic watering system, and a custom circuit to connect the two.
After getting the simple 555 based MC-2100 driver circuit working, we moved on to a controller with more features. I’d been looking for an excuse to make an arduino-compatible board (here’s a description if you’re not familiar), and this seemed like the ticket.
The initial spec for the controller included the following functions:
- Read user input from potentiometer
- Send the 50ms period PWM signal to the MC-2100
- Sense the lathe’s spindle speed using a magnetic reed switch or equivalent
- Display the spindle speed on a 7 segment LED display
At this point, the controller meets the requirements laid out above. I’ll discuss the implementation of each feature into the controller in the order listed above.
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After discussion with Terry in the comments of previous posts, we came to the conclusion that the MC-2100 wasn’t expecting a full 5V signal at the control signal input (blue wire). As shown in the MC-2100 schematic, the optoisolator on the input (U1) has a 22ohm resistor (R2) in series with it. Applying 5V to the blue wire results in 170mA flowing through the optoisolator, higher than its 50mA rating.
This lead to the conclusion that there must be another resistor in the circuit at the dash panel end of the blue wire. Upon inspection, there is a 240ohm resistor in series with the control signal output on the treadmill’s dash panel PCB. With the series resistance at 262ohms, the current through U1 is now 15mA, a much better current level for reliable operation.
Taking things a step further, it’s possible for the circuit to operate on higher voltage if a larger series resistor is used. This allows us to eliminate the 5V regulator from the circuit, as well as the transistor from the output, which was mistakenly added to allow the higher output current the circuit required without the current limiting resistor.
Here’s the resulting circuit (keep reading, not done yet!):
As discussed in the comments of earlier MC-2100 related posts, Terry has been working in parallel to create a circuit capable of generating the variable duty cycle PWM signal that the MC-2100 requires to operate. He’s written up a very thorough summary of his design process (click for the PDF file).
Terry’s circuit uses two 555 timers (or a single 556), two potentiometers (one is a trimmer), and various capacitors and resistors. This is a great way to get the MC-2100 working without the dash panel if you don’t have a comparator on hand.
Following the first day of work, we had nearly completed both the bolt and the charge chamber, and had completed the boltstop. In this session we needed to finish up these parts and create the firing chamber. Brian and I had high hopes going in to this session. He was confident that we would at least fire a shot by the time I had to head home. I was somewhat skeptical! Although we were interrupted by some thermite and Doctor Mario, we were able to achieve this goal.
We did the usual shaping and machining to get the firing chamber roughed out and then got on to the fun stuff… threading. Three parts needed threads. The firing chamber and charge chamber had to thread together at the middle of the gun; and we had to thread the inside of the front end of the firing chamber in order to put one of our Spyder barrels into it. The charge/firing chamber threads would be somewhat simple, as they only have to match each other and require no standardized dimensions. The barrel, on the other hand, has its own thread type that we would have to match. Just to make things more fun, The threads were metric, (M22 x 1.5) and our thread turning gears were standard. Brian worked his magic and got something pretty close to the barrel (7/8 x 16) and we went with it.
External Firing Chamber Threads
Internal Barrel Threads
Whole Firing Chamber
And I have saved the internal threads from the charge chamber for last to present you with a conversation that took place just moments prior to the cutting of the first internal threads we had done.
Joe and I: “Brian are you sure you want to do this without a practice run or anything?”
Brian: “I know what I am doing.”
He apparently wanted our threads to look like the mouth of the Kraken, but as long as he knew what he was doing, who were we to question him! 🙂
The embedded video shows our first paintball break on target.
The graphic above shows the air system we had set up when we fired the gun. Constant pressure is supplied to the firing pressure input, where the pressurized air waits to be released and force the ball from the gun. The bolt is held back by air pressure from the trigger pressure input. Whenever the air gun valve is open, this pressure is supposed to be keeping the bolt to the rear and keeping the gun from firing. Whenever this pressure is released (the air gun is pulled away from the input) the firing pressure should cause the bolt to move forward and the gun should fire. This wasn’t happening for us due to what we speculate to be general surface finish and O-ring fitting issues. With some further work and refinement this should be fixable. We ended up poking the back end of the bolt with random stuff and that provided the motivation required to start the firing cycle.
I was helped out immensely by receiving a reverse engineered schematic of the MC-2100. That enabled me to examine and begin to understand how the hardware of the controller worked together to control the motor. However, it didn’t have much to say about the algorithms contained in the Cypress PSoC serving as the controller’s brain.
Throughout the process of developing a control circuit to drive the controller, I’ve learned quite a bit about the software in the PSoC, and I’d like to share the information. The best way I can think to accomplish that is to document the timeline of my testing, and comment on the results. There’s a lot to read here, but if you’re trying to figure this thing out, I think it will be helpful. Here goes!
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Now that I have an oscilloscope, I’ve been able to learn a lot more about the circuit I’ve been designing for the MC-2100, as well as the MC-2100 itself. However, a lot of people don’t have access to a scope (even one as old and crappy as mine :)). I’ve had an idea for a method of analyzing a PWM signal without a scope for a while now. Last night, I got some time to test my idea and it worked fairly well, so I figured I’d share it here.
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In response to Terry’s comment on my previous MC-2100 post, I got the breadboard circuit hooked back up for some testing. In doing so, I found a couple things missing in my previous schematic. I also may be backing off calling this version of the circuit done. It looks like there may still be a bit to learn :).
I had someone ask for a copy of the manual, so here it is:
With the goal of expanding our electronics tinkering/troubleshooting capabilities, I’ve had my eye out for a cheap oscilloscope on craigslist or eBay. The search paid off a couple months ago when I picked up two old analog Hitachi oscilloscopes, along with a square wave generator and a couple other vintage items.
The scopes in question are the Hitachi V-152F and V-134, seen below. I haven’t been able to locate any date of manufacture for these things, but they’re completely analog. The 134 even has an analog storage function, which is pretty cool.
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This is another quick update on the MC-2100 PWM controller project. I’ve tweaked the schematic a bit to put the 5v regulator at the beginning of the circuit, which I think is a better configuration. This circuit is currently on a breadboard, and worked great until the connections in the breadboard started wearing out (around a month of occasional use, including our paintball gun build day). Here’s the latest (and probably final) revision:
When I started this project, I wanted to get this circuit working without a microcontroller for the sake of education and simplicity. At this point, I’m comfortable with calling that goal achieved. Now it’s time to move on to more features, like a tachometer and possibly closed loop control!
My current direction with this project is to develop a combined tachometer/speed control for the MC-2100 and my lathe. I plan to use an arduino to measure speed, display the speed via 4 digit 7 Segment modules (salvaged from the treadmill control panel), and send the PWM signal to the MC-2100. At this point, Joe and I have a working version of the code put together, and the circuit prototyped on a breadboard. I’ll update with progress once we’ve got something more final.
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