The Sherline Miniature Machinist's Newsletter
Sherline Workshop Project of the Month
Building the worldís smallest steam engines/Iqbal Ahmed and Jerry Kieffer
Iqbal Ahmed of
Kieffer of DeForest,
The engine above could be called a ìMicro steam engine.î Also by Jerry Kieffer, this dual-flywheel miniature is about the size of the flywheel on Jerryís other engine. It comes with its own finger-jointed wooden box with a sliding lid and felt lining. When displayed, the engine and box sit atop a regular #2 pencil eraser. (No, thatís not a giant pencil in the photo.) It has a bore of .029" and a stroke of .032". Injecting air into the .008" intake port with a hypodermic needle will get the two little flywheels spinning away. Jerry says this project tested the limits of how small he could make a working mechanism at the time using standard Sherline tabletop machine tools. Jerry does use a stereo microscope mounted to his lathe and mill for some of these really tiny operations. The Sherline P/N 2125 and P/N 2127 microscope mounts for the lathe and mill were based on Jerryís designs.
Shop Tip of the month
Making and using broaches to make non-round holes/Rich Dean
Broaches are used when you need to make holes that are shapes other than round. A round pilot hole is first drilled, and then a broach of the desired shape is pressed through the hole to remove additional metal, leaving the desired shape. Square, hex, "D" and other shaped holes can be achieved in this manner. Broaches with multiple steps like the ones shown below take less force to use because only a portion of the shape is removed by each step as the broach goes through the hole. The first step is the size of the pilot hole and the last step is the size of the desired finished hole.
The broaches shown above are plain lathe turned, propane torch hardened and tempered in oil. You will have to decide the overall size, shank and dimensions to use for your particular project. Use W1, O1 or whatever drill rod (tool steel). No reason to be fussy. (For a larger, better quality photo see www.sherline.com/tip20.htm.)
MAKING THE BROACH--Turn or machine the profile required to full dimensions, full length. On one end, turn a pilot tip to fit the hole to be broached. If a full form cut is required, this will be the minimum diameter. Otherwise, make the hole oversize to broach only the corners out. That makes it easy on the broach. Next, cut chip slots which form the cutting edges a little smaller in diameter than the pilot diameter. The more edges you have, the less the chip load as the broach is cutting. Now set the lathe topslide (compound slide) to about a 3-5 degree angle to form the clearance angle behind each edge. The amount taken off of each edge is greatest at the pilot end and gets progressively less as you go toward the shank end. Divide 1/2 the diameter difference by the number of edges (minus 1) to find the amount of clearance to cut per edge. Leave the last edge for a full cut.
HARDENING--Using a propane torch, heat the working end to a cherry red in dim light and then dunk the heated part in oil. (An open gallon of motor oil is fine.) Polish a few spots to reveal clean metal and reheat slowly until you see the bright steel areas turn to a light straw color.
USING THE BROACH--To use, support the stock being broached close up to the hole, drop in the broach and push thru with an arbor press. Do not hammer or jam thru by hand. Any misalignment will snap it off. Always, even with brass, lube generously with oil. Also, on full cutting broaches, chip accumulation may jam it, so extract, clean out and push thru for the final cut.
This and more than 50 other helpful tips for Sherline machinists can be found at www.sherline.com/pages/tips.htm.
Books and Videos on Miniature Machining
Learning never ends. Whether you are new to machining or want to take your skills to the next level, there is a lot of good information available in the form of books and videos. Sherline offers a selection of some of the best for the home shop machinist.
P/N 5300, The Home Shop Machinists Handbook/Doug Briney: $25.00ósoftbound, 7.75 x 9.25î, softbound, black and white, 275 pages (Sherline specific)
P/N 5301, Tabletop Machining/Joe Martin: $40.00óthe ultimate book on miniature machining by Sherlineís owner. Softbound, 8.5 x 11î, color, 350 pages, 5th printing
P/N 5305, Machine Shop Essentials/Frank Marlow: $44.95óSoftbound, illustrated, 7 x 10, black and white, 518 pages (General machining subjectsñNot Sherline specific)
P/N 5306, Machine Shop Trade Secrets/James A. Harvey: $39.95óSoftbound, black and white photos and illustrations, 8.5 x 11, 312 pages (General machining subjectsñNot Sherline specific)
P/N 5307, Machine Shop Know-How/Frank Marlow: $49.97óSoftbound, illustrated, 7 x 10, black and white, 520 pages (General machining subjectsñNot Sherline specific)
P/N 5327, Sherline Accessories Shop Guide: $10.00óA collection of all the instructions for Sherline accessories and more. Softbound, 8.5 x 11, black and white, 221 pages
P/N 5328-DVD, Steam Engine Video and Plans/Rudy Kouhoupt: $72.95óDVD, 3 hours, includes plans and materials list to build a steam engine along with Rudy using a Sherline lathe and mill
P/N 5340, The Sherline CNC LatheñA beginnerís Guide/MakeCNC: $27.95óDVD, 44 min. (Basic setup and use of Sherline CNC Lathe)
P/N 5345, The Sherline CNC MillñA Beginnerís Guide/MakeCNC: $27.95óDVD, 53 min. (Basic setup and use of Sherline CNC Mill)
Did you know?
ï All of Sherlineís expertly written and illustrated accessory instructions are available on-line at www.sherline.com/accessor.htm. If you donít want to print them all out, you can always buy the Sherline Accessories Shop Guide. (See books above.)
ï Questions? Sherline has Frequently Asked Question (FAQ) pages that cover both manual and CNC machines. See www.sherline.com/FAQ.htm for basic machine use, accuracy and metalworking questions, or see www.sherline.com/CNCfaq.htm (or .pdf) for questions relating strictly to CNC.
ï If you are building up some production tooling and need small, accurate but inexpensive slides or spindles, Sherlineís Industrial Products Division offers versions of our mill base, spindles and other custom components that give you motion control at bargain prices. See www.SherlineIPD.com for manual and CNC single and multi-axis slides, various forms of spindles and accessories to go with them.
ï Sherlineís CNC cam grinder is now available for sale. See www.sherline.com/CamGrindFlyer1.pdf for details. Building a mechanical machine to grind cams is a complicated process that has stopped many hobbyists from building internal combustion engines in the past. Now the application of CNC to the process and a ready-to-use machine allow this task to be completed in hours instead of weeks or months. Itís great for serious engine builders, machining clubs or engineers designing small prototype machines that require cams.
Upcoming Model Engineering Shows
Estevan Model Engineering Showó
ï Cabin Fever Expoó
North American Model Engineering Society (NAMES) ExpoóApril 30-
Joe Martin Craftsmanship Foundation News
ï The latest addition to the on-line museum is diorama builder Ray Anderson. Ray has published a book on the subject and created some really inspiring and educational dioramas over the years.
ï On Saturday, October 9th we had a visit from the Bay City Rodders hotrod club. See the Group Visits page for photos of the group and their cars and other groups and clubs who have visited the museum in the past. The museum is open Saturdays for groups of 8 or more with at least a weekís notice. †
ï Construction continues on schedule on the interior of our new Foundation offices, shop and museum. The walls are now painted, tile is in and the drop ceiling is almost done. The expected move-in date is now some time in early December. The museum will be closed for a week or two for the move, so phone first before coming if you visit in late November or early December. After the move we hope to begin offering regular Saturday hours.