View Full Version : vertex rotary table

T-Slot

11-02-2001, 10:47 PM

Well, I bought a rotary table on ebay. 6" Vertex. Seems to be good unit. However manual that comes with it is next to useless. Don't understand how to read seconds on vernier scale. Scale has 3 lines either side of zero, the last is marked 60. Assumedly they are 20,40,60., but I can't figure out how to read them. Anybody shed some light on this for me?

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bdarin

11-03-2001, 12:18 AM

I have the same table you do...almost (mine measures 5" dia.) and you're right about the instructions: they suck. I called an OLD ex-machinist friend of mine, a guy named Chip who grew up with verniers and slide rules, and he couldn't make heads or tails of it. Well, hell, if HE can't figure out this vernier thingy, I sure can't. We pretty much gave up on the whole thing and I went out and got me a semi-universal dividing head. I know this hasn't helped or answered your question, but that's my story and I'm stickin' to it. Maybe someone else has an idea.

Thrud

11-03-2001, 12:24 AM

T-Slot;

Great manual, all 3 or 4 pages of it..

Ok. The handle wheel is divided into 4*. The markings go 0,1,2,3. The subdivisions between the (0,1,2,3) are the Minutes (0-60'). The seconds (20", 40", 60") are read as follows. One of the Minute lines will be lined up with one of the Seconds line - that is vernier function - read the seconds line. the Degrees and Minutes are read off of the vernier zero. Easy. Are you glad now they do not graduate them in Radians (2Pi =360*)!

(90:1 worm) 4 degrees per turn of the handle.

1 degree = 1/360 of the circle

1 minute = 1/60 of a degree = 1/21600 of a circle

1 second= 1/60 Minute = 1/1296000 of a circle.

Therefore you can divide a circle in 64,800 divisions (20" accuracy) with your table.

Have fun, measure twice / cut once, be safe.

Dave

T-Slot

11-03-2001, 08:41 AM

Ok, I know how to read vernier scales but these number divisions throw me. In between each minute the vernier lines up on 20,40,and 60 on the left side of zero and then 40,20,0 on the right. The 0 coincides with the next minute reading. That makes 6 divisions, the way I count, which would be 10 degrees each, regardless of what the numbers on the scale say. Does this sound right to anyone?

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Randy

11-03-2001, 10:34 AM

Most of us have been using calculators for 25 years or so, which don't readily work in */'/", so why don't tool manufacturers offer decimal dials? (Sorry, no help, just venting about a pet peeve.)

Thrud

11-03-2001, 11:01 PM

Randy:

Quit buying cheesy calculators! I have used Hewlett Packard RPN calculators since the first Moon shot by Apollo. The current top dog is the HP48GX. It can function completely in Symbolic mode or Numeric Evaluation Mode. This calculator can convert back and forth between different Base systems (binary, hex, decimal, octal) and has a nearly complete units conversion (length, volume, time, weight, blah, blah). It can be used to double check your Honours Math/Physics work (if so inclined).

Its faults? Eats AAA batteries, gets dirt on it. It operates in "Reverse Polish Notation" or "RPN" but can operate in algebraic mode for weinners unwilling to learn something better. RPN calculators execute equations in the same fashion as you would write down the problem and automatically follows agebraic execution syntax.

It gets correct answers where a algebraic calculator lies to you. Easier to use once you understand RPN.

I will get off of my calculator box now...

Dave

jkilroy

11-04-2001, 12:22 AM

Why don't ya'll check out this calulator program for your pc. It is totally free, supports 'as entered', algebraic, and RPN logic. Generally it kicks much butt.

http://www.calculator.org/

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James Kilroy

Randy

11-04-2001, 05:07 AM

Dave,

I absolutely agree with you about RPN. I got an HP-35 in 1975, and now have an HP-32S and an HP-48SX. I can barely operate an algebraic calculator. I even have an "ENTER>=" T-shirt, but I still prefer decimal angles to */'/" just as I prefer decimal distances to fractions. Hail Jan Lukasiewicz! RPN Rules!

T-Slot

11-04-2001, 06:54 AM

Anybody got anything to say about the rotary table topic?

I'm afraid my imagination is faulty -- I can't picture just what the setup is. A picture would help, but I guess there's no way to include images in these notes, is there?

If you can get a digital image of the dial, e-mail it to me. Not that I promise any results....

halfnut

11-04-2001, 11:42 AM

360 divided by 90 = 4 so 4 degrees per turn of handle

The handle dial will have the 4 degrees on it. The minutes are the divisions in between these degree marks. 4 x 60 = 240 , should be 240 marks on the dial.

60 seconds in a minute. The vernier splits each minute into 20 seconds, thirds. Don't need another 60, the zero will work again.

A little redundant having a vernier with only 3 divisions, its close enough. A person can split the lines without a vernier to a reasonable amount of accuracy, like taking a shot at tenths without a tenths vernier on a set of micrometers.

20 seconds on a 6" diameter circle is .00029 on the circumference. See it's close.

So back to your problem, zero lines up, bump handle till another line lines up with 20, thats another 20 seconds, tap a little more till the 40 lines up, tap a bit more and the zero will line up with next division on dial.

Simple, I think, I haven't seen the dial on this rotab but that is how a vernier on a dial works.

Remember 360 degree per rev, 60 minutes per degree, 60 seconds per minute, and your dial is one minute per mark. The vernier is for 1/3 minute or 20 seconds.

Hope this helps, good luck.

T-Slot

11-04-2001, 12:27 PM

I got it! Thanks you guys, I know how the vernier thing is supposed to work but when I bumped the dial around 20,40,60 seconds I was only halfway to the next division on the dial. It finally dawned on me that's because the marks on the dial are 2 minutes each, not one. And the 3 marks on the other side of 0 on the vernier scale get you to the next mark on the dial which is 2 minutes. Good thing Halfnut came along when he did cause I was in the middle of trying to send a picture to SGW that I drew in Paintbrush that would really have you scratching you head. Thanks again, all.

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Thrud

11-04-2001, 11:49 PM

T-Slot,

When I got my HV-6 I drank a 26 pounder of Barcardi 151% White rum and Coke. After half the bottle vanished the manual made perfect sense. And, no I do not drink and machine stuff - that is dangerous - I drink and watch www.wallyandmurk.com (http://www.wallyandmurk.com) and laugh, and laugh.

Jkilroy,

You can "pretend" to be an HP48GX all you want, put no stinkin' pentium can fake it and keep up with it in math prowess or accuracy unless you use mathCad, Maple, or Mathimatica . So there!! (I sure told you) ;-)

Randy,

I feels yer pain brother! I too - after decades of RPN - am unable to operate a non-RPN calculator. I guess you could say we are "equally impaired".

All I have to say is STACKS RULE, man!!!

Dave