# CAD for simple 3-D metal & wood projects?

On 11/25/2013 12:52 PM, Leon wrote:

Like this:
;)
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On 11/25/2013 1:00 PM, Swingman wrote:

No, can you think/tell me what that converts to as a fraction off the top of your head? LOL My calculated industries calculator can't either. ;~)
I like to see fractions, on my drawings, that I can actually come close to reproducing. ;~)
A bit off topic, I checked the outside temp a few minutes ago, 42.51232367 degrees F.
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The measurements may be, but climatologists know the rate of global warming to a tenth of a degree.
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On 11/25/2013 5:59 PM, Jim Wilkins wrote:

Makes for much more sensationalism when graphing and discussing rates of change, akin to measuring crude oil spills in gallons, instead of the standard unit of barrels.
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On 11/25/2013 6:07 PM, Swingman wrote:

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Bzzzzt ... Gotta be teacups, or the granularity is off. LOL
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On 11/25/2013 5:59 PM, Jim Wilkins wrote:

ROTFLMAO!
No kidding I just read, and it has to be true cuz i read it on the internet, that scientist have decided that we in north America and in Europe we are headed doe a mini ice age. Apparently the SUN, that's right THE SUN has been causing the earth to get warm! Well apparently the sun has been falling down on the jolately, maybe the people working for Al Gore gave up. The sun has had much fewer than expected sun spots and as a result we are going to experience colder weather. I always called the global warming thing summer.
Anyway how are we going to be able to afford changing things here on earth so that the sun is not affected, which in turn keeps us from turning into an ice cube???
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On 11/25/2013 6:33 PM, Leon wrote:

Sorry. Old news.
Ol' Sol caught up with the curve last week.
<http://blogs.discovermagazine.com/imageo/2013/11/08/gargantuan-explosion-sun-rips-open-canyon-fire/#more-5329
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wrote:

Indeed. How is the government going to justify raising taxes because of global COOLING?

Fire the astronomers. They're ruining the scam!
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On 11/25/2013 7:25 PM, snipped-for-privacy@attt.bizz wrote:

Same folks that are running obamacare.
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1. Build a giant funnel
2. Attach servo motors so it can track the sun
3. Place over Congress
4. Hot air rises...
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Leon wrote:

Traceable to NIT?
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That is a difference in measurement techniques and machine design. Most machine tools have dials which read on 0.001" (or finer for some machines), but in decimal format anyway.
Way back when, machinists worked to 1/128" at best (the Vernier calipers would measure to that, while scales were marked to 1/64" at best. But then, to make a running fit in a bearing, they would use inside calipers and outside calipers to transfer measurements from one to the other. Bore the bearing hole, take the measurement with an inside caliper, transfer that measurement to an outside caliper (by closing one onto the other by feel -- these had and have no markings) and then machine the shaft to fit the bearing by slowly removing metal until the outside calipers just slide over it with the right "feel". (the calipers will spring a bit, so you need to learn what the right feel is.)
These days, you purchase the shaft, measure it with a micrometer to be sure that it is what it is claimed to be, (in decimal fractions of an inch), make a trial bore with the cross-feed dial on the lathe zeroed, measure the bore it produced, subtract that from the desired size, divide by two (since most machine's cross-feeds are calibrated in radius, not diameter) amd for rough work, just set it and bore. If you need more precision, you approach the final cut in finer cuts, so set that your last cut will be the same depth as the others, measure as you approach it to be sure.
And (on a regular lathe, if you want even finer precision, you set up a toolpost grinder, set the compound at an angle which gives you 1/10th the measurement infeed (5.7392 degrees, but you are likely to only set it near to 5.75 degrees given the accuracy of the compound's built-in protractor, and sneak up on the final dimensions. At last with surface grinding, you don't have the degree of spring that you do with normal turning.
And -- if you need even more precision, you bore and grind to just under size, and then use a roller burnishing tool to mash the surface down to a smoother finish at the desired measurement.
Or -- you use lapping to get that final finish and dimension.
The above is how *I* would approach greater and greater precision on my machines.
This is how it could be done on a manual machine -- especially one in a home hobby workshop (such as mine). CNC changes the game somewhat. But -- the whole time you are working with tools and instruments which read and are set in decimal factions of an inch, so there is never a need to convert something like your 144.531250" to 144 & 17/32", and you never *think* in fractional inches. If you did, you would be reaching for a calculator all the time. Maybe you buy your shafting in fractional sizes, such as 0.500" or 0.375" or 0.125". Yes, these are fractional sizes, but you *think* of them in decimal inches.
BTW    The conversion with my scientific calculator (HP 15C) is done     with no problems -- discard the integer inch part, multiply the     decimal faction by the largest likely denominator (64), see that     it reads an even number, so multiply by two (converting to 32nds     instead of 64ths and get an odd precise integer number, so you     are there. Then add back the integer part of the overall     dimension once you have your fractional part right.
There are *some* digital calipers which will read in both decimal factions of an inch, and in the nearest fractional inch size -- but you are unlikely to find a machinist using one of these for the fractional readings -- which are, after all, just a "nearest fractional size", not a "true reading", or you would wind up needing it to display at least down to 1/1024th of an inch (to be close to the metalworking basic of 1/1000" -- in some fields called a "mil" -- such as in the pin layout dimensions for integrated circuits in electronics -- useful for designing printed circuit boards. Some few of us got into metalworking from the electronics field (as did I), but we seldom mention "mils" as it confuses those measuring in mm (Millimeters -- a very different unit.
I've seen these "fractional reading" digital calipers, but never been tempted to buy them. I just don't *think* in fractional inches most of the time. Some few places, it is convenient. 16 Ga steel is very close to 1/16", so I can convert that to 0.0625" and be close enough to tell 16 ga from other sizes. (And no, that does not work anywhere else, as the larger the gauge number, the thinner the metal. This is related to how it is formed, progressively rolled thinner and thinner, so it is just a lucky crossover point -- and where the limits of my sheet metal brake and shear happen to be, so it is easy to check whether I should try the sheet metal in those tools or not.
Enjoy,         DoN.
P.S.    Not sure why I am bothering to post in this cross-posted     argument, but at least it is metalworking related, not     political. :-)
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Very good description!
I've memorized the decimals down to 16ths but the simple approach is to hang a decimal equivalents chart near the machine, as it also gives the nearest fractional or metric collet size to your workpiece diameter and shows english-metric equivalents.
http://cdn.mscdirect.com/global/images/ProductImages/0651680A-11.jpg
jsw
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On 11/25/2013 1:00 PM, Swingman wrote:

No, can you think/tell me what that converts to as a fraction off the top of your head? LOL My calculated industries calculator can't either. ;~)
I like to see fractions, on my drawings, that I can actually come close to reproducing. ;~)
A bit off topic, I checked the outside temp a few minutes ago, 42.51232367 degrees F.
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On 11/25/2013 1:27 PM, Leon wrote:

ROTFLMAO
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Leon wrote:

Yes. I said you can do it if you want to, but the program is obviously targeted at people who want to use the mouse for input.

It looks like it can take much more precise input than that. There is a setting in the units dialog box. And you don't have to work in fractions. You can switch to decimals and input numbers down to a millionth of a mm. Internally, the data is even more precise than that.
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On 11/25/2013 11:23 AM, jim wrote:

Snip

What gives you that thought. I mostly use the mouse simply to start a line and to give that line a direction to move relative to the starting point. It is keyboard input from there. For that matter you can mostly use a mouse with AutoCAD.
And, if one prefers to use a mouse or a mouse and a 3D input device what difference does it make which program you use as long as the program is capable of getting the job done.
Am I detecting a bit of snobbery here? ;~)
I thought the same about Sketchup when I was using AutoCAD, In fact I had installed and uninstalled 3 different versions of Sketchup before it dawned on me that Sketchup was way better for woodworking than AutoCAD.

That is correct. I tend to input/draw in decimals, much faster than inputting fractions, but work in fractions in the shop so the drawings are also in fractions.
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Leon wrote:

I looked at their promotional videos. I didn't see anything showing off its abilities to make numerically driven models. It looks like it may be okay for cabinet work, but what about something like making the scroll on a violin?
http://www.gussetviolins.com/untitled-1.jpg
http://t1.gstatic.com/images?q=tbn:ANd9GcQKPv8gAgVzHKvZYp10WE4HY1GyHkmZsqZOTP-UKN7lYyduBV9mZg
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On 11/25/2013 1:33 PM, jim wrote:

Should not be a problem. Actually I just down loaded one from the 3D warehouse, rather the whole violin.
http://www.flickr.com/photos/lcb11211/11054578036/
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