The first wash is actually kind of exciting, it’s were you get to really see the fruits of your labor. All the creases and wear patterns really pop after the first wash. Yes you will lose some dye, yes the dye will set, yes the jeans will not fade as fast. But at some point you’ve just got to wash them and move on. Another benefit of washing is that it actually increases the lifespan of your jeans. Seriously, the dirt that gets worked into your jeans through daily use actually functions like an abrasive, wearing down the fibers in the denim and weakening them. Go long enough without a wash and you’re asking for pocket holes and a blown out crotch.

I’ve heard of some pretty strange washing method on the interwebs, including wearing your jeans into the ocean, buying special japanese laundry detergent, and soaking them in a tub with shampoo. Given that some people pay upwards of $500 on a pair of raw denim jeans, I guess I can understand where all the insanity comes from. The below method does not require a beach or japanese soaps, just a laundry machine and a store bought laundry detergent.

First a before shot:

Next turn them inside out:

Set your washing machine to a gentle or, preferably, a hand wash setting. The key here is a low or slow spin speed and cold water. The slow spin will reduce dye loss and the cold water will keep the denim from shrinking. Here’s what mine looks like:

Load up your washing machine with Woolite dark. This is available at most grocery stores.

You’ll want to wash the jeans by themselves as the jeans will give up a bit of dye during the wash.

When the cycle is done hang them to dry on a clothes line. Do not put them in the drier. This will cause them to shrink much more than if you air dry them.

Here’s the after:

I did not notice any shrinkage (in the waist or length) and they still look dark. Plus they no longer smell like a jock strap! My goal with this method was to not shrink them at all, as I liked the way they fit. If you are looking for some shrink, wash them in hotter water (maybe start out with warm) and use a drier.

Still many missing components and systems, most notably:  mold cooling system, pneumatics controls, part ejection cylinder, microcontroller, sensors, power supply,  mounting locations for most components, and many many more.

The pump that transfer the molten plastic is a simple piston pump using two check valves:

http://www.egr.msu.edu/~lira/supp/steam

In my first design I created my own check valves by integrating a ball bearing and spring into the actual pump body. While this made the pump more compact, it also added several machining steps which would have increase the price. So instead I’m using off the shelf check valves that screw into the pump body. Much cheaper, much simpler, and likely to work better.

In another bit of  ”don’t-redesign-the-wheel” thinking I’m using an electric deep fryer as the melting pot. Candles makers already are using this as a melting vessel. This already has a heating element and thermostat built-in, and it only costs ~$30. Compare that to several hundred dollars had I made my own vessel from stainless, used silicone band heaters, and made my own temperature regulation. The latter would have definitely been cooler looking, but for this project I’m trying to keep costs low.

Not as cool as stainless steel and band heaters.

I am at a bit of a crossroads design wise. I’m deciding between using pneumatics or electric actuators for motion control. Pneumatics are more impressive visually and give me a chance to learn about pneumatic systems (plus they make a neat pssst pssst sound), however they require an air compressor (loud) and are more expensive.  Using electric motors would make the system smaller, as I don’t need to house a compressor and air tank in the enclosure.

I’m leaning towards pneumatics provided I can find a quiet air compressor. I’ve read of people re-purposing a refrigerator compressor, but I’m concerned about their CFM rating and live span.

I’m also looking very seriously at buying a small mini mill. I should recover the cost of the machine and then some verses paying to have it done. Ideally I could find a small Chinese mini-mill on Craigslist, but I haven’t seen much out there. Maybe I’ll just break down and get this guy:

http://littlemachineshop.com/3900

Replacement parts are easy to come by. You’ll need part numbers 1K087-760 (the window) and 1K104-529 (the tape). The cheapest parts can be head directly from Nikon 1-310-414-8107. You don’t need to be an authorized dealer or repair shop, anyone can call and order parts from Nikon. They’ll even look up parts for you if you don’t know the part number.

Replacing the LCD window is easy enough. Start by removing the bottom cover. Keep track of the screws. There are a few near the batter compartment that are longer, and one hidden screw beneath a small flap also near the battery compartment. Also don’t forget the ones near the bottom of the lens mount.

The bottom cover should lift off, nothing else is attached to it. Next remove the rear cover. Its got screws on each side, near the eyepiece, and under the SD card door. Remove the SD card. The rear case will not come out with a card installed.

The rear case will be held on by one ribbon cable. Flip the latch up and slip out the ribbon cable.

Flip the case over and the remove the screws holding the metal backing plate to the rear case.

Getting the LCD cover out of the rear case can be tricky, the glue is very strong. I pushed the cover from the back and it cracked in two, then I removed the broken pieces.

Remove any of the doulbe sided tape that did nto come out with ehthe LCD cover.

Apply the new tape to the rear case keeping one side of the paper backing on, that way you can press down on the tape getting a good seal.

The new LCD cover should come with some protective film. Remove the film on the back and align one side to the rear case. Avoid touching the uncovered side of the LCD cover, finger prints will be stuck behind the cover FOREVER.

If the buttons fall out don’t worry, they are all keyed and will only go in one spot.

Now put it all back together!

I’m not sure why.

I wanted a sleeve that would enable me to recognize it amongst a pile of laptop cases.  Just about every sleeve follows the same formula as Incase: form-fitting neoprene and a zipper. One of the few manufacturers making something different is ColcaSac (formerly AppleSac). What they make is basically the opposite of the Incase sleeve: natural materials, velco flap, and not formfitting.

I got the Hanakapiai model. (note: I really don’t care for the name. It’s like when those Swedes at IKEA name all their furniture ridiculous sounding words no one likes having to pronounce, see: ”Blürg Vørsāts”). Fortunately the name is really the only thing I dislike about this sleeve.

The exterior fabric feels like a burlap sack, but a little softer, definitely not scratchy. While the interior is lined with a faux lamb/sheep fleece.

Genuine faux fleece

Unlike neoprene sleeves, the ColcaSac is not form-fitting. The initial fit is very tight, so tight that the velcro flap would hardly close all the way and I struggled to pull my laptop out of the sleeve. However after storing a laptop in it for a few weeks the fabric stretched out and now I can slide a laptop out fairly easily and close the flap over all the way. It still takes a bit of a pull to slide out my laptop. I think of this a positive as it keeps the laptop from slipping out, if, for example, you were running with your sleeve open and tripped.

One advantage of this style of sleeve is the increased corner protection. Neoprene sleeves offer little to no corner protection when dropped. The ColcaSac corners are squared off which results in extra material on the corners. While I doubt it would protect from a fall of say 6 or more feet. A short fall from a coffee table or counter should not turn your screen all sorts of pretty permanent colors.

Another feature I like is the integrated pouch for storing your AC adapter. Unfortunately you cannot store the adapter with the extension cable in place. You have to either remove it or use the small flip out plug.

The only issue I see with an adapter in the pocket is pressure being applied to the top of the screen. However after a few weeks of use I see no reason for concern. If you’re really paranoid you can always remember to put your laptop in with the screen side facing away from the  pocket.

Sleeves from ColcaSac are price similarly to Incase, that is, more than you would expect to pay for some fabric and velcro/zippers. If you can get used to the slightly larger bulk vs. neoprene, the ColcaSac is great. I highly recommend giving them a try as they appear to have a good return policy, in the event you find it’s not your bag (zing!)

Also, if I’m going to be doing more reviews I really need to develop some kind of rating system. Like stars, or wrenches, or lolcats.

I’d give this ColcaSac sleeve 4 out of 5 lolcats

BONUS PICTURES!

http://www.scribd.com/doc/37301298?secret_password=1ehb8rphnat7ykzt6zu3

MAR machines use a process called gas-assist injection molding, a hybrid process somewhere between blow molding and injection molding. In traditional injection molding, usually resulting in solid objects, a small amount of plastic is injected into a mold where it cools completely and then is ejected. In blow molding, resulting in hollow objects, a tube of semi-molten plastic is clamped between mold halves at which point air is used to push the plastic against the mold. I’ll go into detail on the method the MAR uses a little later. The designers probably used gas-assist as it speeds up the cooling time of the plastic ultimately reducing the cycle time to around a minute. If traditional methods had been used the figurine would have been very small (lame) or the cooling time very long (>5 min). Seeing as this was basically a kids attraction at museums, theme parks and zoos you’re going to have a hard time getting kids to wait around 5 minutes to get their toy.

The manual describes the components, layout, and operation of the major subsystems.

Mold-a-rama subsystems:

1. Hydraulics
   1. pump and motor
   2. reservoir
   3. lines
   4. rams
   5. valves
   6. hydraulic fluid (oil)
2. Pneumatics
   1. air compressor
   2. valves
   3. air tank
3. Cooling system
   1. refrigeration unit
   2. heat exchanger
   3. water pump
   4. water reservoir
4. Plastic system
   1. Melting pot
   2. pellet hopper
   3. injection ram
   4. air ram
   5. air/plastic valve
5. Electronics
   1. rotary actuator
   2. solenoids
   3. power supply

Missing from the service manual are descriptions of the actual injection molding components. This is the most important part of the system to understand if I am going to recreate the MAR. Fortunately I found the original patent, US3068518.

http://www.google.com/patents/about?id=R0hgAAAAEBAJ&dq=3068518

It’s written in typical patent verbiage, meaning you have to reread everything a few times to understand it. The relevent part to me are the drawings and specific descriptions.  The basic operation goes like this:

1. mold halves close
2. molten plastic is injected into the mold cavity.
3. air is blown into the mold to remove excess plastic
4. Cold water is circulated in the mold halves
5. mold halves open
6. ram ejects plastic figure.

The heart of the machine is the valve which controls the flow of plastic and air into the mold, lower right number 15 below.

Basically by using a sliding bar (17) that alternately blocks the plastic inlet (75) and the air inlet (81) The mold is filled then cleared.

Here’s how the valve works.

Rod 78 functions as both a pipe to transfer air to the mold and an actuator to move valve 17 to the first and second position. In position 1 the valve is pushed to the left, which allows plastic to flow into the mold. After the mold has been filled completely piston 84 and valve 17 move to the right, position 2, closing off the plastic fill port and opening port 81 which fills the mold cavity with air.

The next diagram illustrates the filling process.

In figure 6 you can see the two holes in the bottom surface of the mold that do the filling. 63 is the entrance and 64 is the exit. Plastic is pumped in to completely fill the mold, to the point that the excess flow out 63. During this time chilled ~40 degree water is pumped into the mold halves to cool a thin layer of plastic to the inside of the mold.   The cylindrical valve(17) then slides over covering the plastic fill port and revealing the air fill port, blowing air into the mold shooting the un-cooled plastic out the exit port (64).

If you look at the bottom of mold-a-rama figurines you can see the remains of the two ports.

Fill port top, exit port bottom.

Some general notes on the operation:

• The plastic/air control valve (15) is heated to prevent liquid plastic from cooling and jamming the moveable valve.
• A freon based refrigeration system is used to cool the water, via a heat exchanger, that goes to the mold halves. This is loud, expensive, and large. I will replace this with solid-state peltier cooling if possible.
• The mold-a-rama does not run on a continuous basis, like say an injection molding machine in a factory, rather is operates sporadically throughout the day, maybe 10 to 200 times a day, going minutes or even hours between cycles.  As a result this alters the way the plastic is melted. Rather than using a heated screw auger to melt the plastic and force it into the mold, the mold-a-rama uses a heated pot filled with molten plastic at all times. When the machine is run plastic is pumped from the pot into the mold. I’m debating where or not to use the MAR design in my implementation or the traditional screw auger setup as I dislike the idea of having to continually heat a pot of 250 degree plastic at all times. It would be nice if I could heat the plastic on demand, but that may increase the cycle time.
• The most common media is polyethylene pellets (Tm = 250F). I found that earlier machines use a different plastic that is more like a brittle wax, susceptible to melting if you left your toy in your car on a hot day. I may play with the idea of using paraffin wax (Tm = 120F) instead of plastic as a proof of concept. The much lower melting temperature and re-usability would be useful during the prototype phase.
• The patent shows a submersible motor and pump to transfer the molten plastic from the pot to the valve and eventually to the mold. It’s clear that the original manufacturer changed this for the production machines, probably realizing that motors and pumps sitting in a tub of 250 degree molten plastic is not great for pump/motor life. They appear to have switched from a motor and pump to using a hydraulic piston to transfer the plastic. This is still somewhat of an unknown, I need to research how you can use a piston to transfer the molten plastic from the pot to the valve.
• In the patent they show a large pot. I found that they switched to a smaller pot and a refill hopper for the final design. The small pot has a float that senses the level of the molten plastic. When the level gets too low a motor is activated that turns a screw auger to transfer pellets from the hopper to the pot. While the motor is turning the auger it also turns a paddle in the heated pot to ensure the pellet are incorporated into the molten plastic.
• The pot and valve are heated using electric heater elements, not the steam heater in the patent.
• Being designed in in the 50′s, the electronic control system is entirely analog. A slowly rotating motor turns a shaft with cams at different angles which in turn activate switches. This has got to be a pain to work with, so I’m going to replace it with a microcontroller.

]]> http://thingsimdoing.wordpress.com/2010/09/12/diy-mold-a-rama-how-it-works/feed/ 0 thingsimdoing Screen shot 2010-09-12 at Sep 12 6.15.10 PM Mold fill Screen shot 2010-09-12 at Sep 12 6.24.25 PM mold15 http://thingsimdoing.wordpress.com/2010/08/03/diy-mold-a-rama-an-introduction/ http://thingsimdoing.wordpress.com/2010/08/03/diy-mold-a-rama-an-introduction/#comments Wed, 04 Aug 2010 04:01:36 +0000 thingsimdoing http://thingsimdoing.wordpress.com/?p=276 ]]> About an hour ago I discovered an awesome machine from the 60′s called a Mold-A-Rama (MAR):

More info here: http://www.tampabay.com/features/humaninterest/article1015315.ece

Video of its operation here: http://www.youtube.com/watch?v=I_sJxxeB5Lo

The Mold-A-Rama is basically a small production injection molding machine, complete with metal water-cooled mold halves and an injection ram. It created small (<5″x5″x5″) plastic figurines, and was usually found in museums and zoos.

Here’s my plan:

1. Research
   • Find out as much as I can about how the original MAR works. I have already found a service manual, and there actually is an old (still working) MAR near me.
   • Establish the state of current DIY injection molding machine. From what I’ve seen so far, the hobbyist and DIY machines are more of a single shot system, taking a considerable amount of time to prepare the mold, fill, and then eject the part. The MAR is closer to a production injection molder, capable of reproducing parts rapidly.
   • Further research production injection molders. While I have a basic understanding of the process from my manufacturing engineering class as an undergrad, I need to dive deeper into the mechanics of these tools.
2. Design
   • Incorporate what I have learned from my research. The goal is not to build an exact replica of the MAR, but to take the idea and update it with modern technology. I plan to replace the electromechanical controller with an arduino, the freon based cooling system with a solid state cooler, and so on.
   • Create CAD model of design. Most likely the design will be modeled in Solidworks, however I may use this as an opportunity to learn Pro/E.
3. Source parts
   • I will have a limited budget for this, mainly because I’m not sure what I’ll do with it when I’m done. Most of the parts will likely come from industrial surplus suppliers and eBay.
4. Build
   • Use tools to make it? In my garage?
5. ?????
6. Profit

That’s it for now. Let the great experiment begin!

In a move of remarkable engineering Canon decided to make a critical high-stress pin out of plastic. Who would have guessed that a tiny plastic pin would break after being flexed 20,000 times? The only way to really fix the issue is to install a new metal pin, which Canon eventually did.

Cross section of Rebel mirror box

So, let’s get going! (Note: you need to say this like Brian Fellows)

There are plenty of guides out there on disassembling the Rebel, google is your friend here.

Once you have the front and rear covers removed, take off the top cover, but don’t remove the wiring for the flash.

To get to the sub-mirror pin out you need to remove the flash capacitor and PCB on the right side of the camera. Some places will tell you that you can twist the board out-of-the-way without removing the orange ribbon cable. This is ridiculous. It’s much easier to spend 60 seconds desoldering the orange melamine cable, than playing PCB contortionist for 10 minutes.

This is where the flex cable attaches to. Remove it and the single screw and the PCB will swing out nicely.

Now the pin is clearly visible.

Use a small screwdriver or metal pick to remove the broken pin, it’s glued in from the factory.

Based off the hole diameter and the width of the lever that slides on the pin, I machined a replacement from some brass stock. I still have the dimensioned drawing somewhere. I will add it to this post when I find it. Also you don’t really need to machine a new pin, I just happened to have access to a lathe. You can fashion one out of a paper clip if you want.

Slide the new pin in, make sure the sub-mirror lever (circled below) slides over the pin.

Cover the head of the new pin in epoxy. Avoid using cyanoacrylate (super glue) as the off gassing from it can fog the internal optics.Once the glue is dry test out your new repair. Lift the main mirror up, the sub-mirror should flip-up flush into the main mirror (as above) and the shutter should be completely visible.

Now just reinstall the flash PCB and assemble the rest of the camera.

Your Rebel should be back to normal.

Although at this point the Rebel is almost 7 years old. So this is likely just a sign you should buy a new a camera made in this decade.

The cause of this problem is that the USM ring motor (#4 below) is not applying enough pressure to the focus ring (5). Pressure is applied to the focus ring via a spacer (1), wave washer (2), and a felt ring(3). When you have this issue you can still hear the USM motor moving, but the focus ring does not move.

Photo credit: Piers Hendrie

Piers believes the issue is that the felt washer has worn and it now too thin. He solves this by adding additional shims, which fixes the issue for him.

I think the more likely cause is that the wave washer has relaxed and is no longer applying enough pressure. I verified this by increasing the height of the spring (dimension C in the below figure.)

Wave washer

I did this by  pinching each bend on either side with my thumb and forefinger and increasing the amount of bend in each of the waves of the washer. Doing this increases the height of the washer, and makes the diameter slightly smaller, so when you go to put it back on you kind of have to stretch it to get it on.

After reassembly the autofocus work great, and no additional shims were required.

]]> http://thingsimdoing.wordpress.com/2010/02/14/canon-ef-20-35mm-f3-5-4-5-usm-autofocus-repair/feed/ 1 thingsimdoing __IMG_6132 SpringWashers-dwgs-B http://thingsimdoing.wordpress.com/2010/02/10/bike-light-parts-arrive/ http://thingsimdoing.wordpress.com/2010/02/10/bike-light-parts-arrive/#comments Wed, 10 Feb 2010 05:52:14 +0000 thingsimdoing http://thingsimdoing.wordpress.com/?p=225 ]]>

All the parts for my mega P7 bike light have arrived. The driver from Kai Domain came relatively quickly, but the P7 LED emitter from Deal Extreme took forever to arrive. Of course the driver came without any sort of labels or instructions so I’m going to have to search the candlepower forums to figure out how to hook it up. Now that I have all the parts I am going to draw them in solidworks and start designing the housing around them. The reflector ended up being much larger than I had thought so I may not use it.