CAD for simple 3-D metal & wood projects?

Bob's right about that being interesting, but it might not be clear to the wood butchers here that it's actually possible to turn out more accurate work than the machine on which you're doing it.

It's necessary to tweak a few things, like spindle runout and angular alignment between bed and spindle centerline. The first is done by measuring bearings from a large stock of them made to lower specs until you find some that are round within your desired tolerances. The latter is an adjustment any knowledgable machinists is capable of.

BTW... that selection of parts thing is how some manufacturers 'manufacture' super-precision parts of the same design as their 'regular' parts. Then they just supply different drawings. A Poisson distribution of parts says that if they're centered about the spec, some known amount will be of a better spec, in a narrower slice of that curve. After knowing and doing all that, with careful work and a knowlege of how the work, tools, and machine itself flex and change with temperature, you can make a part MORE accurate than the machine.

So... you 'bootstrap' yourself up. Make more accurate machines progressively until you're at the limit of the materials (thermal, mechanical flex, etc).

Because there was a time when all woodworking tools were hand-forged, the woodworking guys forget that without metal machinists, their endeavor wouldn't be as accurate or easy as it is now.

Having spent around 20 years working woods with traditional tools, I very much appreciate modern power woodworking equipment.

Lloyd

Reply to
Lloyd E. Sponenburgh
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Yes Lloyd keeping on painting with that brush. You get into many "discussions" that carry on and on?

Reply to
Markem

Try this:

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jsw

Reply to
Jim Wilkins

Markem fired this volley in news: snipped-for-privacy@4ax.com:

You bitch about the color I'm using, but you don't even pay attention to what it IS.

I said, "The guys who are harping on (it)"... Not ALL woodworkers, and not everyone else; just the guys who are denying.

If you paid closer attention, you might actually not hate the 'decor'.

I'm kind of strident about 'good work' because I design machines to manufacture explosives. You don't get many 'second tries' in that endeavor.

Lloyd

Reply to
Lloyd E. Sponenburgh

Social Equality requires that no one should be allowed to challenge their fragile self-esteem by displaying more knowledge or possessions.

The fundamental difference between right and left is that seeing innate differences prompts the right to improve themselves, the left to tear the others down and demand political cures for their psychiatric deficiencies.

jsw

Reply to
Jim Wilkins

Most have not denied it just asking question to understand the jargon that does not jibe with they're own experience. Your reading of text only gives you 7% of communication at best, might want to keep that in mind.

I have been paying attention nor have I bitched, just posted an observation.

Mark

Reply to
Markem

In the Automated Test Equipment industry we needed to buy electronic components at least 10X more precise that the ones our machines tested. Close-tolerance resistors came either from early in the run before the equipment drifted off setting, or were custom spiral-ground to a measured value with a narrow diamond wheel. The process was autometed enough that they made a profit grinding custom orders to

0.1% precision for $5 apiece.

Analog Devices supplied us with hand-selected op amps which I think came from near the center of the wafer where diffusion was more uniform than around the edges.

jsw

Reply to
Jim Wilkins

First of all most of the examples of precision that have been given involve no 3d modeling at all. And the rest appear to be at best 2d modeling (e.g.. a lathe profile).

I'm saying that any CAD system can produce geometry that is far more accurate than any manufacturing process. If a 3d computer model has dimensions that are different than what you like them to be, it is because of the input the software was given, not because the software is sloppy.

A program like Sketchup caters to people who want to model something that looks good without paying much attention precise numbers. But that doesn't mean it is sloppy. It just means it is not as easy to hit the exact numbers you may want as in other programs that cater to people who want models driven by precise numerical inputs instead of mouse actions.

Reply to
jim

Huh? I guess you didn't check out my offerings?

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Lofted to .01 inch, since traditional nail in the floor lofting considered 1/8th inch superb fairing.

Reply to
Richard

jim fired this volley in news:dZCdnTMPefxT9g7PnZ2dnUVZ snipped-for-privacy@bright.net:

You hit it right on the head. That's why it's not suitable as CAD, even though it's an extremely useful system for visual presentation.

And although I might not have made it clear... that was my whole point on base-1.

Lloyd

Reply to
Lloyd E. Sponenburgh

"jim" wrote in his blissful ignorance

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"The axis position feedback system uses a 0.5-nanometer scale to reliably track axis motion commands programmable in steps as small as

10 nanometers."

I've watched a large aspherical Germanium infrared camera lens being diamond-turned to a mirror-like submicron finish on a CNC lathe.

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All you demonstrate is that YOU don't know how to do this.

jsw

Reply to
Jim Wilkins

I did look. And its nice work. But you aren't claiming that you took a 3d model and produced a part held to tenth accuracy. If you can achieve .01" accuracy in manufacturing that hull to match the 3d model, that would be extraordinary accuracy.

Reply to
jim

Except that what you quoted as justification for your "whole point" is incorrect, therefore you're still wrong.

With SketchUp, "precise numerical inputs" can be input to the same precision as AutoCAD, by simply using the keyboard.

Try again ...

Reply to
Swingman

I'm going to take exception to your wording in your last paragraph. Maybe I misunderstood.

I was an AutoCAD user for about 8 years, other CAD programs since 1986.

Anyway I am a furniture designer and builder. I have completely converted over to Sketchup.

Now where I might be confused with your wording is that if I draw something that is 4" long it is precisely 4" If I draw 4.015625, I get a line that is 4 1/64" long, precisely.

Now if you are talking about a higher degree of resolution, I would a agree that Sketchup begins to round after the fourth digit right of the point. .0001

In woodworking drawings it it is typically not necessary to measure in increments that are smaller than 32ths of an inch.".

While that is true, Sketchup can still very accurately draw in increments that are 1/64" or greater. Anything with in that resolution works out just fine.

And for what it is worth, You can type in precise distances just like with a CAD program with in the resolution that Sketchup operates.

After drawing a complex piece of furniture with Sketchup, sometimes with hundreds of separate components I use a plug in program that takes the exact over all dimensions of every component and imports that data, accurately, into an optimization program that has my inventory of materials. I cut the components overall sizes using the optimization program with no reference to the Sketchup drawings of the actual project.

I will reference the drawings for specific details for each component that may need to have tenons, dado's, slots, mortices, ect.

Reply to
Leon

Lloyd, you simply do not know how to use Sketchup to its extents. Your comments show your ignorance about Sketchup. I'm not trying to belittle you but most every thing you have mentioned about Sketchup is inaccurate.

Again, I switched from AutoCAD to Sketchup about 6~8 years ago because I get the same needed resolution and accuracy.

I am a woodworker and routinely work with pieces that measure in 1/8" resolution however the program is quite capable of accurately and quite quickly drawing a box that is 4 1/16 x 5 3/64 x 9 19/32.

don't knock the program until you actually learn how to use it, not just play around with it.

I would be more than willing to show you some detailed drawing that I have done with Sketchup.

Reply to
Leon

Only for presentation, and depending upon the resolution you have set.

For dimensional computations, SketchUp still uses its internal accuracy, the same as AutoCAD.

Reply to
Swingman

Speaking of which, I have a plug in for chaining the units, precision of the units, type of units, etc with out having to open up the Sketchup Dialog box.

Reply to
Leon

Yes that machine should be able to cut 3d parts so they match the 3d computer geometry to within a tenth. However, the CAD model of the part can be made a million times more accurate than even that machine can manufacture.

I didn't say there were no way to produce complicated 3d parts that are within a tenth of the 3d CAD model. I said that I doubt anyone reading this was doing that. You still haven't changed my mind.

Turning something on a lathe doesn't need a 3d model. That is not 3d machining.

And watching someone else do it doesn't count as doing.

Reply to
jim

Here, do this:

Open SU, go to Go to Window|Model Info|Units|Fractional and choose 1/64" or whatever Format you desire .

Now, draw a rectangle of any size using the rectangle tool

Select the rectangle and right click Area|Selection

You will see a number representing the area of the rectangle you selected to .000000 precision.

Reply to
Swingman

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.

Reply to
jim

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