General News and Events
The third meeting of the Home Shop Metal Club was held on July 20th. There was some confusion about the location of the meeting do to an error in the map. This has been fixed. The map on the back page is now accurate. We are still not sure if we want to get a DBA to operate are funding, but we should be able to get that worked out next meeting, on August 17th. We may have to vote on a change to the by-laws regarding the handling of Club funds. George Marsden suggested that we compile a list of videos related to machine work and investigate the posibility of renting or borrowing them for use by members. We are also looking for ways to help publicize the Club to help increase membership and participation. George Edwards dropped by my office the other day with a neat little brochure holder he purchased at Office Depot. Rutland has offered to place brochures on their counter for us. Don Foster brought a couple of neat little "Huff 'n Puff" engines that would operate off the pressure of a person's breath. Good work Don!
Of Special Interest
As always, we will be needing articles to publish in this Journal. If you would like to submit an article, idea, or photograph there are several ways this can be done. The best way to submit an article in machine readable form. A plain text file is the easiest to work with. It can be placed on a floppy and mailed to my home, or, attached to an Email and sent via the Internet. Articles and other ideas can also be faxed to my office at (713) 251-3860. This is a Spring number, and will be a toll call for most of you. If you have any photographs of projects, I would like to try to publish them here. If you have a scanner, send me the scanned image file in JPG or TIFF format over the Internet or via US mail. If you don't have a scanner, send the photo in the mail, or hand it to me at a meeting. I don't think the FAX will work well enough. Also, mechanical drawings in DXF, WMF, CGM, or AutoCAD DWG are easy to put into the newsletter.
Sources of Supply
Add these to your list:
REX Supply Corporation
General machine shop supplies and machines.
3715 Harrisburg, Houston, Ph 222-2251
Lathop Jeweler's Supply
Jeweler's supplies, small tools, etc.
6704 Ferris St., Bellaire, Ph 665-0614
I used to go to a jeweler's supply in Sharp's town and they had a very good supply of small precision tools, furnaces and chemicals for plating and treating metal. I don't think they are there anymore, but Lathop probably has the same stuff.
John's "Poor Man's" Clamp
Clamps are so frequently used but sometimes there are not enough on hand or not of the right type. For those who get enjoyment from making their tools or fixtures, the drawing shows an inexpensive adjustable clamp that is easy to make. A small clamp is shown and made from a piece of 2" schedule 40(std. wt.) or heavier pipe that is 1 1/2" long and cut into quarters. Weld or braze a one half section of 3/4" pipe onto 2" pipe for purpose of forming a rounded surface for a center of rotation. This piece is drilled with an elongated hole for a stud. A spacer piece is cut from bar stock and shaped on one end to fit curvature of 3/4" pipe and drilled for the stud. Larger clamps are made using larger sizes of pipe; remember that the smaller attached pipe forms a curved surface for seating the stud.
Tech Topics - 2 and 4 Flute End-Mills
Information presented here is based on the experience of the writer. Opinions are invited. The question of two flute verses four flute end-mills comes up from time to time. I hope this information will help clarify the use of these tools.
Two Flute Endmills.
Four Flute Endmills.
An interesting thing about the two types of end-mills is when they are used for slotting. A four flute end mill, although it is more rigid than a two flute, will tend make a rougher finish than a two flute will. This is because there is two edges cutting at the same time. If you can imagine cutting a slot from right to left ( table moving toward right) on a work piece. The flute that is at the 9:00 position will be cutting and the torque will be forcing the bit toward 6:00. The flute at 6:00 will be shoved into the work, causing it to grab and cause torque the bends the bit toward 3:00. This relieves the cutting force on the 9:00 flute, and the cycle begins again. This causes a lot of chatter. A two flute end mill only has one flute cutting at a time, therefore the chatter is much less.
If you are machining the edge of a work piece, the story is quite different. Imagine squaring the end of a piece of bar-stock. It is in the vise with the edge to be squared to the right. The table will be moved toward the operator (normal milling, not climb cutting). The flute at 9:00 will be doing the cutting. It will be causing torque that is forcing the mill toward 6:00. On a four flute mill the flute at 6:00 does a very good job of resisting the bending force, and hence, less chatter and a better finish.
Hints and Kinks
To quickly mount work-pieces square to the table on my milling machine, I have two 1/4" holes drilled and reamed near the back edge of the table. They are about 10" apart and were both done while the cross-feed was securely locked. Use a center drill to start the hole, and this will help assure accurate positioning. Drop a couple of pins made from drill rod into the holes, shove the work-piece against the pins and clamp it down. The pins can be pulled, if necessary, before the piece is machined.
The last Hints and Kinks talked about using Toner Transfer System available at EPO. They have been out of it for some time now, sorry. Another source is Techniks, Inc. Ph (908) 788-8349. Ask for Press and Peel Wet.