The Sherline Miniature Machinist's Newsletter

Number 29, May 21, 2010

http://www.sherline.com


Sherline Workshop Project of the Month

A nested cube machinists puzzle made using CNC/Tom Hubin

NOTE: This project can also be made using careful drilling and boring operations without using CNC. Machinists made these fun puzzles for years before CNC was available.

1.††††† 2.††††

3.†††† 4.

The photos above show various stages of the machining of the puzzle. It is simply a number of accurate boring jobs in a row.

This is a project done on my Sherline 5410 mill using TurboCnc 3.1a.

Directions for using g-code file 3cubes.cnc to machine 3 nested cubes. (File: 3cubes.txt copyright Tom Hubin, 26 November 2004

1. Start with a 2-inch cube of 6061 aluminum. This can be a 2 inch length cut from 2 inch square bar stock.

2. Mill or fly cut the outermost 1.950" cube from the 2 inch stock. Be sure to machine something from all six sides so that the finish is attractive.

3. Label the six sides as top, bottom, right, left, front, rear.

4. Drill 3/8" diameter center holes into top, front, and right surfaces to a depth of 1.5". These three holes will pass completely through the innermost cube. I used the 3/8" end mill holder with a machine screw length 3/8" diameter drill bit.

5. Drill 3/8" diameter center holes into bottom, rear, and left surfaces to a depth of 0.75". These three holes will not touch the inside of innermost cube. That way the 3/8" diameter center holes through the innermost cube will be seamless.

6. Secure the 1.950" cube in a vise and use an edge finder to accurately locate the rightmost surface and the rearmost surface so that the center of the topmost surface is at (X,Y)=(0,0).

7. Load a 3/8" diameter x 5/8" LOC aluminum roughing end mill. Move it over the topmost surface. Lower the bit until it just touches the topmost surface. I usually do this by loosening the bit so that it drops down and touches the topmost surface. Then tighten the bit just enough so that it won't fall out.

8. Run the program. You will be prompted to touch the surface with the end mill. You have already done this so continue.

9 The bit will be raised and you will be prompted to tighten the bit and start the spindle at 2800 RPM, which is max spindle speed on a Sherline mill. Tighten the bit securely then start the spindle.

10. Stay near the machine, lubricating and clearing chips as machining takes place.

Here are the CNC files in various formats. Right click on a file to save it to your computer or open it with the appropriate program.

3CUBES.CPP (3cubes.cpp is a plain text Borland c program to generate the gcode file.)

3CUBES.OBJ

3CUBES.PRJ

3CUBES.BAK

3CUBES.EXE

3CUBES.DSK

3CUBES.CNC (3cubes.cnc is plain text gcode for TurboCnc 4.01.)

(NOTE: If you cannot open these files, try downloading the ZIP file that contains all the original files. To do so, CLICK HERE.)

The remaining 3cubes.* files are binary files generated by the Borland C++ compiler but are not needed.
*.txt, *.cnc, and *.cpp are plain text files and can be read and modified with just about any DOS, Linux, or Windows text editor. DOS Edit command can be used. I use the shareware DOS text editor PcWrite. Microsoft Notepad, WordPad and Word are Windows text editors that can be used.

Here are some websites to help visualize the nested cubes:

http://www.dakeng.com/gallery.htmlóDan Statman's dime sized nested cubes. Small and very very classy.

http://www.grapevineglassworks.com/landscapes/cube.htmlóArtwork showing nested cubes with no hole through the center.

http://www.geocities.com/barxe/cubering.swfóAnimation showing something similar but here just for fun.

http://www.token.crwoodturner.com/magiccube/óShows inner cubes detached so as to tumble freely within outer cubes.

óTom Hubin
thubin@earthlink.net

See this and other CNC projects at http://www.sherline.com/CNCproj.htm.


Shop Tip of the month

Adding an electronic RPM readout to your lathe or mill/Normand Ouellette

By adding a Sherline DRO to your lathe or mill you get a readout of RPM in addition to the X, Y and Z position readouts. However, they cost $325 and $395 respectively. If you want just the RPM readout, here is a way to get it for less money. You also get the bonus of a readout of engine run time and a reminder of lubrication intervals. Normand Ouellette shows you how.

The readout unit is glued to the top of the headstock on the lathe. The second photo shows the sensor glued in place using epoxy. The last photo shows the readout box glued across the headstockso it reads properly on a mill.

ìI just finished installing anRPM/Hour meter on my new lathe and mill. I ordered the ìSenDECî RPM/ Hour meter. This will allow you to keep track of the oil interval on the lathe or mill and set the closest RPM needed. I ordered from SenDEC the unit that sells for about $70*, took it out of the wrap and glued it to the headstock with epoxy. Hereís how:

1. Glue the meter on top of the headstock with a dab of epoxy as seen in the first photo

2. Glue the magnet on the shaft with a drop of epoxy as seen on second photo

3. Glue the probe on the headstock out of the way with some epoxy as seen in the second photo

Thatís it. Installation took about 10 minutes.

The part number is Part#: SFT806-0222 hr and rpm meter. Here is the link: http://www.sendec-products.com/index.php?option=com_content&view=article&id=110&Itemid=136

It keeps track of RPM from 10 to 6000, total hours count of the unit is up to 10,000 hrs (then it needs replacement) and it in reminds you of a service interval every 4 hours of operation for lubrication.î

óNormand Ouellette, Laval, Quebec, Canada

*NOTE: Current price of the gauge on their web site is $89.95. It may be available from other sources if you do a search.

This and more than 50 other helpful tips for Sherline machinists can be found at www.sherline.com/pages/tips.htm.


Product Spotlight

Adjustable Tailstock Tool Holders

One of the advantages of the Sherline lathe is the ability to swing the headstock so that tapers can be cut without the use of a compound slide. The down side of this adjustability is that the lathe has moving parts instead of being machined in one piece or pinned for perfect alignment between headstock and tailstock. The normal alignment can be adjusted to within a few thousandths of an inch, which is all that is normally needed for most jobs; however, some jobs, particularly in watch making or when using tiny drills require near dead-on alignment. For those jobs, adjustable tool holders are available.

How they work

The #0 Morse taper of the back plate of each of these tools goes into the tailstock spindle. The front plate of each is held to the rear plate with two screws that go through slightly oversize holes. This allows some adjustment between the front and rear plates so that the tool held in the front plate can be adjusted until it is in perfect alignment with the drive spindle in the headstock. The various front plates hold a live center, a drill chuck, a threading die or various tools you can make yourself for special jobs. This is a good way to take full advantage of the versatility of your Sherline lathe without sacrificing absolutely perfect headstock-to-tailstock alignment when it is needed.

To read the instructions on how these tools are used CLICK HERE.

P/N 1201óAdjustable Tailstock Live Center ($65.00)

P/N 1202óAdjustable 1/4" or 3/8" Tailstock Chuck Arbor ($45.00) Thread on either a 1/4" or 3/8" Jacobs or Rohm drill chuck for perfect centering.

P/N 1203óAdjustable Tailstock Tool Holder ($45.00) Use a split collar you turn yourself to hold a variety of sizes of boring or other round shank tools of your choice. This holder is also designed to hold the P/N 2085 WW collet adapter or the P/N 2086 8mm collet adapter, allowing tools to be held in WW collets in the tailstock.

P/N 1204óAdjustable Tailstock 5/32" Chuck Arbor ($45.00) Instead of a thread, the front plate has a male #0 Jacobs taper to press on a 5/32" Jacobs chuck with the ability to hold very small drill bits.

P/N 1206óAdjustable Tailstock 1" Die Holder ($60.00) A ring is included so it can be used to hold 7/8" diameter threading dies as well.


Did you know?

ï Sherline attended the North American Model Engineering Society (NAMES) Expo in late April. See a few highlight photos from the show at http://www.sherline.com/names10.htm.

ï Sherlineís Home page has recently been redesigned to make navigation a little easier. The navigation bar at the top has white type on black for easier readability and there is a prominent link to our new Facebook page. Other items have been condensed or re-located so you get to the important partóthe main menuómuch quicker.

ï Find links to instructions for all of Sherlineís accessories at http://www.sherline.com/accessor.htm. This is a tremendous resource for the new machinist who hasnít yet purchased these accessories but wants to know how they are used.


Upcoming Shows

ï The next show Sherline will be attending is the Western Engine Model Exhibition in Vallejo, CA on July 10-11, 2010. Hosted by Model Engine Builder magazine and the Bay Area Engine Modelers club, you will get far more than your moneyís worth. The admission is only $7 for both days, and you will see a huge selection of steam and gas engine models. Where else are you going to get to hear a miniature Hemi V8 or supercharged Challenger V8 run?


Joe Martin Craftsmanship Foundation News

The Joe Martin Foundation recently closed escrow on a new $1.7 million, 16,500+ square foot building that will soon be the new home of the offices, machine shop and museum. Only Ω mile west of our present facility, it is actually located in the city of Carlsbad rather than Vista. Construction will soon begin on the inside of the building, and we hope to be moved in by early 2011.

ï Two new craftsmen have been added to the on-line museum. Roberto Heijmans of the Netherlands has constructed a huge all-wooden model railroad in 1/25 scale. Everything from the track to the engines and cars to the bridges and structures is made from wood. Also just added is Swiss auto model maker Roger Zimmermann who has made a couple of highly detailed models of some unusual 1960ís American cars.

ï Last week the museum was visited by over 30 members of the Temecula area Early Ford V8 club. CLICK HERE to see the ìClub and Group Visitsî page for some photos.

ï Michel Lefaivre barely beat the volcanic ash cloud out of Paris, France in late April and was able to fly to the NAMES show in Detroit to receive his award as Craftsman of the year. See coverage HERE and on his page.

ï Two significant items were added to the museum last week. Les Cade donated a º scale Rider-Ericson Sterling pump engine and Dandelyn OíConnor donated a model of a Greenland trawler called the Nordkamp built by her late husband Mike. They can be seen on the ìOther Projectsî page on the museum web site if you canít visit the museum in person.