Saturday, May 23, 2015

Redneck Lathe DRO

Having digital read outs (DROs) on my mill has spoiled me, so I've been wanting to add them to my lathe. One idea I've seen has been to adapt inexpensive digital tire depth gauges bought on eBay for under $10. I tried this out tonight. Here's my proof of concept redneck lathe DRO:

I setup the lathe with a 3/4" diameter aluminum rod in the chuck and the DRO affixed to the saddle and cross slide with magnets. My goal was to turn the rod down to 1/2", which would require advancing the tool 1/8". (When turning down stock in lathe, since you're cutting a rotating piece, you divide the amount you want to remove in half, then move the cutting tool that amount. E.g., 0.75" - 0.5" = 0.25" to remove, thus you move the cutter in 0.125", or 1/8".)

Unfortunately, it's not going to work, as it's not accurate enough. I turned the stock down until the DRO read that I'd moved the cutter in 0.125", but when I measured the rod, I got 0.490". It was off by 1/1000" over such a small distance, which in metalworking terms is too coarse.

I'm going to go ahead and try the iGaging DROs, which a lot of mini mill and mini lathe owners have had good results with. I'm planning to install one for the cross slide and another for the compound.

Wednesday, May 20, 2015

Cut My First Single Point Threads

I'll be adding info about this to my machining site, but thought it was worth posting here as well.

Tonight I cut my first single point threads on my mini lathe. One of the advantages that the Chinese-made mini lathes have over the American-made Sherlines and Taigs is that they can be used for thread cutting without any additional attachments. To setup the lathe to cut threads at the desired pitch, you change gears in the headstock. A good explanation of the procedure can be found in the Little Machine Shop Mini Lathe User's Guide (PDF).

After finding my change gears and the reading the threading section of the LMS guide, I was able to cut 1/2x28 threads on the end of this 1/2" 6061 aluminum rod:

1/2x28 is of course the standard thread used for muzzle devices on .22s and 5.56mm firearms. E.g., my Ruger 22/45 Lite's barrel is threaded 1/2x28.

The cutting tool I used was from a set that I got at Harbor Freight shortly after I bought the lathe, with 1/4" shanks. I used some Tap Magic as cutting fluid but I probably could have cut these threads dry. (I've used a lot of WD-40 as cutting fluid when working with aluminum since I got my lathe and mill in 2013.)

Since I'm just learning how to thread on the lathe and wanted to reduce the risk of crashing the tool into the chuck, I got a spindle hand crank from Little Machine Shop. It fits into the spindle the same way a bicycle handlebar stem goes into the head tube.

Aside from safety, the spindle hand crank gives you lots of low speed torque. However, if I ever want to thread a barrel I'll have to do it under power, because the hand crank blocks the spindle bore.

Also shown in the above pics is a chip tray that I fashioned from some sheet steel and attached to the cross slide using a couple existing holes. I ran across this mod on the web somewhere and thought it was a good idea. It should keep the ways a bit cleaner. Here's a better view:

If the chip tray gets in the way of a job it can be easily removed.

Thursday, May 14, 2015

External Battery Packs for Cell Phones, Tablets, Etc.

Most of us rely on cell phones, tablets, and maybe a GPS unit in our daily lives and out in the field. Smart phones are basically pocket computers and it's easy to become reliant on them to augment our own knowledge. Unfortunately, they eat electricity and many of the most popular models don't have replaceable batteries. That's where an external battery pack comes in.

External battery packs range in size from units the size of a lipstick to large blocks. Modern battery technology is allowing manufacturers to cram more amp hours into smaller units, but if you want more than one phone recharge, or need to recharge more than one device, you're going to have to buy one of the larger units.

Last Fall I picked up an EasyACC 15,000 mAh pack from Amazon, and used it on my Fall deer hunting trip. It's about at the limit of what I'd call pocket-sized. The two USB ports can theoretically be used to simultaneously charge two devices, although one port puts out 1.5A and the other puts out 2.1A. However, if one of your devices requires a 2A minimum input then you'll be limited to charging one device at a time.

Aside from the big pack, I also have a smaller unit from Duracell that I picked up when I bought my first iPhone. I carry this one in my EDC bag to and from work, just in case there's a foul up during my commute and I need to give my phone a boost.

Friday, May 08, 2015


Pi Finder

I'm putzing around with my Raspberry Pi again, and came across Ivan X's Raspberry Pi Party site. One of the utilities he has which you may find useful is Pi Finder, a program to find and connect via SSH to your Raspberry Pi running in headless mode, when you don't know its IP address. Pi Finder is an app that runs on Mac OS 10.5+.

If you need a similar app that can run on Windows or Linux (plus Mac OS X), check out Adafruit's Raspberry Pi Finder.

New Commo Blog

Another commo-related blog worth checking out:

Communications Tradecraft

Updates to my Machining Website

I made a couple updates to Dave Markowitz's Machine Shop:

Thursday, April 30, 2015

Redding #2 Powder Scale

After loading up some .308 on Tuesday I came to the conclusion that the Lee scale I've had for several years is a total POS. It's hard to zero, too light so that it moves if you look at it wrong, and just feels cheap. So,  I got a Redding #2 powder scale from Amazon to replace it. It's ~5x the price of the Lee but it's much nicer and easy to zero. Additionally, the Redding will measure up to 505 grains, vs. the 100 grain capacity of the Lee.

I also got a set of Lyman check weights, and according to them, the Redding scale is right on.

Note: A lot of reloading equipment is from Lee. E.g., Classic Turret Press, various sets of dies, hand priming tool, and a bullet sizing die. They work great and fantastic values, but their powder scale just isn't up to snuff, IMHO.

Tuesday, April 21, 2015

Barnett Recruit Recurve Crossbow

The Barnett Recruit Recurve crossbow that I ordered from Amazon came today. Intended quarry include deer, feral cats, and zombies.

Just kidding about the cats.

I went with a recurve crossbow because I wanted a simpler, more user-serviceable design.

The kit included the bow, 3 hex wrenches, red/green dot sight, quiver, 3 Easton XX75 bolts with 100 grain field points, a spare bolt retaining spring, and a tube of string wax the size of a Chapstick. I also ordered 2 x 5 packs of carbon bolts w/100 grain field tips, along with a rope cocking device (RCD) and extra string wax. The RCD and extra wax were shipped separately and got delayed. (I think they are using USPS for the second package. Grrrrr.)

The draw weight is 150 lbs. with a 12.5" power stroke and I'm just able to cock it without the RCD as long as I wear gloves, so I took 3 shots after I put it together. Point of aim was the bullseye on the deer's chest in the pic below. The trigger isn't bad; Barnett advertises it at 3.5 pounds. The distance to target was ~10 yards. I'll zero the sight after I get the RCD. There's a fair amount of vibration when it's shot so I'm glad that I used blue Loctite on the screws when I assembled it.

"Muzzle" velocity is supposed to be ~245 FPS. The minimum weight bolt you can shoot is 340 grains but Barnett recommends a 400 grain bolt (including the point). The fiberglass prod came strung, which greatly eased assembly. I need to pick up a stringer and a spare string.

The crossbow only weighs about 5 pounds as you see it above, a lot less than the compound xbows I've held. The width is around 27" so it doesn't feel cumbersome. It has studs for QD sling swivels and the LOP is adjustable. It has an "anti dryfire" safety. Unless there's a bolt loaded you cannot disengage the safety. I need to figure out a way to make the safety quieter because it's kind of screechy (metal rubbing on metal).

Barnett recommends that you wax the string serving and flight rails every 5 or 6 shots to reduce wear, and to wax the whole string when white fuzz appears.

My initial impressions of this crossbow are good. We'll really see how it shoots once I get the cocking device and get the chance to wring it out.

Edit 4/22/15 to add:

The package with my extra string wax and rope cocking device arrived this evening and I was able to take a few more shots with the crossbow. The RCD makes a huge difference in cocking the bow. I will probably shorten the RCD a little, to make it a little easier to use with this setup.

One more accessory I'm going to see if I can find is a small stock pack that I can strap to the buttstock. I'd use it to store the RCD, a tube of wax, and hex wrenches on the bow.

Thursday, April 09, 2015

New iPhone 6

Last night I went to the local Verizon Wireless store and upgraded my phone from an iPhone 5 to an iPhone 6. The 5 was about two years old and starting to get sluggish, plus the battery life was deteriorating.

Since I backup my phone to my laptop, I had to wait until I got home to restore from the backup, but before doing so had to upgraded iOS on the new phone. That went pretty smoothly, except that I had to delete and reinstall CloudMagic before it would let me setup my work Exchange account.

So far, what I like about the new phone is the greater capacity (64 Gb vs. 32 Gb), faster CPU, better call quality, and larger screen. I am not wild about the smooth rounded sides, which make it less secure when holding it. However, I have a Magpul case on order from Amazon which should arrive tomorrow to eliminate that concern.

I'm hoping that the iPhone 6 will have better battery life than the 5 but it's too early to tell. The camera should be better, based on the pictures I've seen taken with my wife's iPhone 6.