Category Archives: Engineering

3D printing

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I’ve had 3D printing on the brain for the past few weeks for some reason. I’ve been thinking about putting together a kit 3d printer to get started. I was thinking how I would like a relatively large work area (not the small limited 6″ or 8″ cubed that a lot of the cheaper printers provide.

Then last evening it came to me. The light bulb came on.
Use the milling machine as the printer! Just get a print head, and control it from the existing software (Mach3). The work area is huge, and the cost should be quite reasonable since I only need the extruding head. Between a good quality plastruder, and a temperature control board, it should be about $250 ($170 for the plastruder, stepper motor driver and $60 or so for the temp control board)

Feed speeds of a makerbot are around 40mm/s (2400mm/min). Currently I can do about 1000mm/min on my milling machine (which is 1/2 of the makerbot speeds) but with a ballscrew upgrade I should be able to do about 5000mm/min feed speeds (83mm/sec).
I have read about some kit 3D printers (like the Ultimaker) that can do 200-300 mm/sec feeds (12,000-18,000mm/min). I know my mill will never go that fast.

Resources:

Mach3 as 3dprinter software (here)

Good info on whats required in order to use Mach3 as the river software (here)

Enclosure for CNC machine

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I’ve been spending some time thinking about a method to enclose my CNC machine.
There are lots of ideas… (pictures). (another link) (enclosure build log 01)

One key thing is that I want easy access to the CNC table so I can easily add heavy items like vices, rotary tables, etc. And the encluse needs to be somewhat modular so that I can take parts of it off in case I want to work on/service the cnc machine.
The three sides (left, right and back) will be plywood construction. That part was easy.

The chip/coolant tray was the second hardest part to figure out, but I think I have a design for that.

Thirdly is the front door to the enclosure.  Since I have walls on the left and right side, the width is set. My initial thought was to make side-to-side sliding doors using full extension kitchen drawer slides. Depending on how large I wanted the opening to be, I could use either one sliding pane (per side) or two nested panes (per side) to allow more of an opening. For a door system that uses two nested doors per side, I would need  4 pairs of slides. Each pane needs 2 slides; one for a bottom track, and one for a top track.
But then I came across these Over The Top Slides.  I can make the door as wide as I want, and flip it up and push it over the top in one motion. Or if one door gets too heavy, split the door into two. Only drawback is that the slider only comes in 14″ lengths, which means it can only accommodate for 14″ of travel. Continue reading →

Standing workshop bench

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In the new house, I’d like to move to a standing workbench, and computer desk and abolish sitting except at at the dinner table to eat. So in the basement, where the workshop will be, I want to build myself a workbench, and a computer desk that is both stylish and functional. The workshop space will be shared with a small theatre space, and I’d prefer to not have 2×4 work benches if I can get away with it.
Both computer desk and workbench will be 44″-47″ tall (haven’t decided yet on a final height).

UPDATE:
– Having used the workbench, it would be useful if I could adjust the height of the table a little. The current height of about 46″ is great for detail work, but working on larger components it’s a little high. It’s hard to lift heavy objects to this height, and applying lots of force is more difficult at this height.
– For the computer bench this should be no problem as not much force is applied at this height.
– Looking for a slick method to raise and lower the table surface. Since the counter is pretty heavy, I want a method to lock the height which is also rigid (and won’t create a wonky table surface). Maybe something based on a thread and a couple of stepper motors to raise and lower the work surface??
Continue reading →

Multiroom audio for retrofit home

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Looking into how I’m going to get audio into the different rooms of this house where there is no structured wiring in behind the walls to take advantage of.

http://www.avsforum.com/t/1341706/any-alternate-product-just-like-sonos

http://www.musicmultiroom.com/

UPDATE: pricing out some components, and I think I will go the DIY route with a squeezebox backbone. I have a squeezebox classic and radio already. In each room that I just want some music that doesn’t need to be played at loud volumes I can put a squeezebox radio (they go for about CND$100). In the living room I can use a squeezebox classic or squeezebox receiver with some quality speakers and a small class T amp to drive them. As a reference, the Sonos Play:5 is $450. For that kind of money I can put together much better components (speakers, amp) that will be much louder.

For compact class t amps, read this: http://madgoat.hubpages.com/hub/High-quality-inexpensive-mini-power-amplifiers

More on what small amp to use with a squeezebox: http://forums.slimdevices.com/showthread.php?91027-Stylish-tiny-amp-for-Touch/page1

100W Class T amp on ebay (w/ power supply): http://www.ebay.ca/itm/2-X-100W-Class-D-Audio-Amplifier-Combo-Kit-w-24V-350W-Power-Supply-TK2050-/350604100288?pt=US_Home_Audio_Amplifiers_Preamps&hash=item51a1a202c0#ht_4095wt_1080

A lot of the class D or class T amps seems to be based on the Tripath integrate amp chips. TA2020 is a 30W amp(@ 4 Ω), TK2050 is a 100W amp (@ 4 Ω) .

This also looks like an interesting option. In wall keypad to control with amp built in: http://www.pyleaudio.com/sku/PVC8U/In-Wall-Background-Music-Amplifier-with-USB-And-SD-Card-Player-With-35mm-Input-Jack-For-iPodiPohne-and-Volume-Control

AF Assistant IR-measuring

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Made some progress today.

Measured the wavelength of a couple of Canon AF assist lights.

AF assist light from a Canon 540EZ flash.
The wavelength is about 725nm.		 AF assist light from a Canon 550EX flash.
The wavelength is about 700-715nm.

Now to look for some LEDs in that wavelength.
The other requirement is that the light source needs to be able to handle several hundred mA. (so the 20mA regular LEDs are out of the question)
I did find a 1W 730nm IR emitter at DigiKey that may do the trick. I’ll have to order one and try it out.

Variable Pitch multi-rotor craft

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A post on RCGroups got updated last night. A new variable pitch multi-rotor craft got posted, and it looks very slick. This got me motivated again in continuing my work in this field.

While looking for the heli parts that were used in the above post, I came across this RC helicopter manuals collection of helis I never heard before. It’s good to know about it and see how other helis are designed and put together, for future ideas.

http://macgregor.co.uk/support/heli-manuals.htm

AF Assistant IR 1.0

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Work on the new AF Assistant has gotten to a point where I thought I would post some progress.

First off, the name is slightly changing. I am calling this one the AF Assistant IR. This will be version 1.x
As the name implies I am working on using an IR lightsource (well, near IR) from a Canon 550ex. I have mounted the LED module in a case which sits under the camera. It mounts to the 1/4-20 threaded hole on the bottom of the camera. The unit is still triggered by the remote shutter release port on the side of the camera just like the AF Assistant v3.1

Fig 1. Pattern at 3 ft.

I have chosen to align the light so that the projected pattern of the module is horizontal (as opposed to the vertical line the laser  AF Assistant put out). Due to the fact that the pattern is not just a line, and that the module is closer to the lens axis then a hotshoe mounted device, parallax errors in alignments are quite small. It seems that (in the first alignment of the LED module), the center focus point can pick up  on the projected pattern from 3ft to infinity. That’s more then enough for me. I can probably tweak it to get a closer distance, but I’ll play with that later.

Fig 2. Pattern at 30ft.

Several advantages are already apparent by using the LED module.

– The pattern that this puts out is quite wide. So wide in fact that with a 50mm lens on a full frame sensor (of a 5d mk2) the side (left or right) focusing points are able to use the pattern.
– The light the LED module puts out is quite dim. Figure 1 (at 3tf) was taken at ISO6400 , 1/30, f1.4. Figure 2 (at nearly 30ft) was taken at ISO25600, 1/13, f1.4. In a totally dark room, at 30ft, I can just barely see (with the naked eye) the pattern on the wall 30 ft away.

For both the 3ft test, and 30ft test I was focusing on a flat wall with no features (in full light, the camera can not focus on the wall, since there’s nothing there to focus on) and with the AF Assistant IR light, I can focus on the blank wall at 30ft away even with the side focusing points. Quite impressive.

Some internal details

Fig 3. LTC3490 LED driver in action

I have moved away from the 1 battery setup of the previous version. The LED is drawing up about 250mA (which is 10 times what the laser was using) so I figured I’d move up to 2 x AA cells.
I have also moved away from thru hole for most components. Surface mount technology is what I’ll be focusing on from now on.

The LED driver IC is a LTC3490. It can drive up to 350mA though  I cannot drive this LED that high. The LED module heats up too much for my comfort. At about 230-250mA it still gets warm but I can keep my finger on it indeterminately. Anything above that current and I can’t keep my finger on it for too long. There is a trimmer pot on the board so I can adjust the current to the LED but I may take it out in the production version.

So far all the tests are looking very positive. The other surface mount IC is a MAX4289 op-amp. It’s able to run on low voltage (down to 0.7V). Most other op-amps need at least 3 volts to run, which I may not have if I’m running two NiMH batteries at 1.2V a piece.

Fig 4. Fully populated board

I’ve only been playing with this setup for a couple of days, and will be testing it at music festival next weekend.

UPDATE:

I took some measurements of the wavelength of light from a couple of AF assist lights form Canon flashes. Read about them here.