Here is a list of all the postings Rick Sparber has made in our forums. Click on a thread name to jump to the thread.
|Thread: New Kid on the Block|
Thanks for the very kind words. I typically write one article a day and post them on my web site. Just now I posted one on getting a better longitudinal cut on a cylinder using a horizontal/verical bandsaw without measuring. I used the "twang" of the blade to tell me what to do. If you are interested, please see http://rick.sparber.org/cibc.pdf
As for going to the UK - I have been twice. Once on my honeymoon and once with my two daughters. It is like Mecca as far as I'm concerned. There is no better place to go to see examples of machining history. If MEW wanted to pay my way, I'd be there! By the way, after my older daughter went to the Kew Steam Trust, she was hooked. She eventually earned a Masters in Mechanical Engineering and helps design jet engines (proud papa...).
First, let me say that I greatly appreciate you telling me that the article was unclear. Only with such feedback can I hope to improve my writing style. I hope you will keep asking questions until you understand what I was trying to say. Through your questions I will learn what to improve.
Let me first address your question and then try to clarify the article.
A finger Dial Test Indicator really measures the angular movement of the finger. If you secure it to a stand and put something under it, you can zero the dial. If you put something else under it and again read zero, you know that the two things are at the same height. This is the only case where a finger DTI is accurate. If it reads a non-zero value, the error in the reading is a function of how far the finger rotated. So for maximum accuracy, you can only trust a finger DTI when it reads the same value as it read when it was touching a reference surface.
In the article, I am using the finger DTI to tell me when I am on the surface of my precision slope. Using a DTI this way is more accurate than just chucking up a rod and banging it down on the surface.
The precision slope lets me greatly magnify vertical motion along a horizontal axis. Say the slope is 1:100. Then for a 100 mm movement along the X axis I will get a 1 mm vertical movement. Conversely, if I move 1 mm on the X axis, I will see 1/100th of a mm movement on the Z axis. This extremely fine control of movement combined with the repeatability of sensing a surface with a finger DTI, lets me set my end mill precisely.
How much of this precsion a given machine can give depends on the condition of the machine. If, for example, the quill was loose, then the end mill might bounce up and down 0.5 mm. This limits the machine's accuracy to no better than 0.5 mm.
Have I made matters better or worse with this explaination?
I think you have chosen a very worthwhile project. Many people do the same function by just moving the apron on their lathe back and forth with the motor off.
Is your goal to have this machine or the journey involved in making it? If you just want to have one, then maybe you can find a junk machine that can be modified. If it is the journey, which is usually my case, then maybe you would be interested in casting the parts yourself. You would need scrap aluminum, sand, clay, charcoal, and time. That is how I made my drill press:
It is great to "see" so many old faces! It is warming up here too. Will be above 115F in no time
I am very active on a few Yahoo forums and never stopped writing.
IMHO, the DRO350 is a very good machine but does have a few minor problems both in the electronics and software. I tried my hand at improving the Human/Machine Interface and was very happy with the results. But without the ability to change the firmware, it was purely an academic effort.
If you do own a 350 or 550, here is a fix that might improve the stability: put a 450 ohm resistor across power and ground of each slider. Early testing shows it helps with power up and noise immunity. YMMV.
Even though my machine is very small and manually powered, I have already had a mold leak. After the first small burn, I've learned to stay away. Of course, I always wear eye protection.
Guilty as charged.
Thanks for the warm welcome. I too have not received issue 188 but hope the publisher will send me a complementary copy. My local bookseller does not carry it.
Although I find stationary steam engines amazing, most of my effort is similar to yours. I like solving problems I find in the shop. My last entirely new area is injection molding of plastic. Great fun! I can make a finished part in under 2 minutes and a very low cost. The machine is based on the one designed by Dave Gingery.
My name is Rick Sparber of Phoenix, Arizona, USA. The April 2012 issue of MEW contains my first article in this magazine. Most of my articles end up at my web site, rick.sparber.org but a few are published in Home Shop Machinist and Machinist Workshop.
It was difficult for me to write the MEW article because I do not have a sense of who my readers are except for "Alan" who encouraged me to approach MEW. Thanks Alan!
So my initial goal here is to learn who you are, what interests you, and how well you tolerate my rather strange writing style.
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