The Owad Laboratory

Sonar trumps eTape

I’ve given up on the Milone eTape entirely. I just couldn’t get it to work reliably. Instead, I decided to go with a RadioShack Ultrasonic Range Sensor as my backup method for detecting water. It’s mounted on the basement ceiling and will alarm when it detects an inch of water on the floor. The floor is sloped, so an inch isn’t nearly as bad as it sounds. It’s been working well. I’m leaning towards a pressure transducer for the main sensor.

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Calibrating Milone eTape

Milone's eTape is proving to be rather finicky. Per Milone's instructions, I have it installed in a 1" pipe, so that it can't stick to the sides. Readings fluctuate by up to 1/2", even with no change in water level. The eTape seems very sensitive to any sort of pressure. It needs to be suspended to give a proper reading. I neglected to suspend it during one test, and in an empty pipe, readings gradually reached 14", apparently just from the pressure on the bottom of the tape. Worse, according to this discussion, it appears that the eTape can be permanently damaged if it is submerged. That seems to contradict the Operating Instructions, which state:

The vent hole allows the eTape to equilibrate with atmospheric pressure and must not be submerged in the fluid to work properly. The vent hole is fitted with a hydrophobic filter membrane to prevent the eTape from being swamped if inadvertently submerged.

I've emailed Milone for clarification.


According to Chris at Milone, it's ok to submerge the vent hole, but submerging the connector tab will permanently damage the sensor - a detail I'd have thought would be worth mentioning in the Operating Instructions. The newer eTapes that come in tubes are sealed so that this isn't a problem. Chris says that bare eTape can be sealed by using RTV or Silicone II to completely cover the connector tab.

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Prototyping a Sump Pump Controller

Most mechanical relays and switches are rated for 1 million cycles or less. That sounds like a lot at first, but if you have a sump pump that runs every 30 seconds, that's less than a year. Lowes used to sell a sump pump with a lifetime warranty. Every year, the manufacturer would mail me a new switch, and about every three years, a new pump, until they finally insisted on refunding my money.

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Rebuilding a Porter Cable 18V battery

I have a large collection of 18V Porter Cable tools. The oldest are from 2010, and the batteries are starting to fail. I've heard that Harbor Freight's 18V battery uses the same cells. A new Porter Cable battery is about $40, whereas the Harbor Freight battery, with the ubiquitous 20% off coupon, is just $10.40.

Both batteries open by just removing a few screws. The Porter Cable battery is better packaged, but the layout of the cells is identical:

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Unboxing the Laser Cutter

The Chinese 40W laser cutter, sometimes called the K40, has been around several years now, and prices have finally dropped below $400. After waiting for discounts to line up, I was finally able to purchase one last week for about $360 shipped. How bad (or how good?) is a $360 laser cutter?

The unit is larger than I pictured it, given the cutting size. The box is 37"x25"x16". With its weight and bulk, it was too large for me to get my arms around, so I slid it in the front door and unboxed it.

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Raspberry Pi Zero and NTC CHIP size comparison

CHIP is on the left, Pi is on the right.

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CHIPbag - Customizable Case for NTC's C.H.I.P.

CHIPbag is a customizeable case for Next Thing Co's C.H.I.P..

Options in Customizer, or by downloading the attached OpenSCAD file, include:

Standard or Low-Profile design
Openings for headers
Opening for battery connector
Screw mounts added to sides
Bitbeam added to sides or back
Building bricks added to sides or back

I'm making a lot of tweaks yet, but wanted to share.

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C.H.I.P. is here!

My alpha version of Next Thing Co's new $9 computer, C.H.I.P. arrived today, straight from Hong Kong. The fun begins!

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Grizzly’s PA Moving Sale and New Benchtop Bandsaw for 2016

Grizzly announced this month that they’ll be closing their Muncy, PA showroom and warehouse at the end of October. I visited on Saturday, for what normally would have been the fall tent sale, but was a moving sale instead. As of this writing, all new in-stock merchandise is 10% off and floor models are 15% off. Demo Shop units are advertised as 25% off, but there’s essentially none left.

If you’re in driving distance of Muncy, it’s worth stopping in. For a $1,495 cabinet saw like the G0690, you’re not only saving $150 off the retail price, but you also avoid the $150 freight charge. A particularly good value is the G0771 hybrid saw. It’s currently on sale for $675, which, after the discount, brings the price to $607.50. When the sales are over, the price with shipping will be $895. (I use these examples because they’re the two saws I was torn between buying.)

Grizzly’s flier says that “all items must go”, but one employee told me that five tractor trailers of tools and equipment leave daily for Missouri. Granted, those tools are leaving, but if there’s something you need, I would suggest getting it now rather than hoping that the discount will eventually drop.

Grizzly has several tent sales each year, where they sell damaged and returned merchandise. There were tent sale items are for sale in the warehouse, but far fewer than at a typical Grizzly sale. There are no table saws left, and probably not enough woodworking equipment in general to warrant a trip, if tent sale tools is all you’re looking for. Metal working machines were more prolific, and there are quire a few small lathes left in particular.

I ended up purchasing a 7x14 Mini-Lathe and two cute little Shop Fox Micro Mills. The new lathe will hopefully replace my Shop Fox Micro Lathe from an earlier sale. It’s a brand new unit, but the control box was damaged in shipment. A new control box was included and it looks like all the parts are present. We’ll find out soon. As for the mills, one is missing the x-y table and the other is supposed to have a bad motor. (The bigger problem is that I don’t actually need another milling machine.)

The best deals at a Grizzly Tent Sale are in the first minutes after the doors open and a few hours later, when they’re ready to negotiate on price. I made all my purchases later on, so I had a good bit of time to wonder around and talk to people.

One person I was excited to get a chance to speak with was Shabir Balolia, Corporate Manager and son of founder Shiraz Balolia. We talked about the closing of the Muncy location, which he said essentially came down to two causes: First, the cost difference between shipping from the Missouri and Pennsylvania locations to the east coast is negligible, with Missouri sometimes even being cheaper. Second, visits to the showroom have declined significantly, while internet orders have skyrocketed. Speaking personally, I’ve often stopped at Grizzly’s immense showroom and been the only person there, so I can understand the reasoning.

Shabir also spoke with me about his plans for a new benchtop bandsaw. It will be the first benchtop bandsaw to feature a carry handle and upper/lower ball bearing blade guides, as well as other innovations. Shabir was excited to talk about it and clearly expects it to be the highest quality benchtop bandsaw on the market. Look for it in the 2016 catalog or on Grizzly’s website, come January. Shabir asked that I not share any other specifics, but definitely keep an eye on Grizzly if you’re planning a small home workshop.

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Setting up Cura and OctoPrint for the Mini Fabrikator (Tiny Boy)

I recently bought a Mini Fabrikator (TinyBoy) on the advice of Ex-parrot.

The instructions describe how to set the printer up with Repetier-Host. Ex-parrot uses Octoprint. Print time can take hours, so I decided to use Octoprint as well, installed on a Raspberry Pi, so that my MacBook won't be tied down while printing.

I'm using the latest version of Octoprint (1.2.5). I tried installing the latest version of Cura (15.06.03), but the option for non-Ultimaker printers seems to have been removed, so downgraded to 15.04.2, which is working well.

Below are screenshots of the settings which Ex-parrot recommended to me. I've done about a half dozen prints so far and haven't felt the need to make any changes. Comments with suggested tweaks are welcome.

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