Question for the No-DRO Crowd

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Harold_V
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Re: Question for the No-DRO Crowd

Post by Harold_V »

Edge finding on multiple sides can really complicate things because you may not be able to use the original data points as you pick up additional edges. That would certainly be true for using dials, although by recording each edge without changing the dial setting would work, but one must be quite comfortable with math to avoid making mistakes. One of the advantages of dial settings is that one typically zeros a dial, so readings relate to dimensions in a way that trigger a red flag when they don't add up.

The exact four corner dimensions are important if one hopes to make pockets without undercuts. I'm not suggesting multiple edge finding won't work, but it's much easier to make the typical edge find (top left corner for the typical manual mill setup) and work from there. That, of course, depends on where the print for the piece in question provides the required dimensions. Rarely will one find double dimensioned parts drawings, which is poor practice.

There are some serious advantages to working all features to tight tolerances, one of which is that if you must locate from a particular edge to accommodate a setup, multiple parts can be so machined without fear of making scrap. That's particularly true of cases where the body dimensions of a part may have a tolerance of ± 1/32" (or even ± 1/64"), but particular details may be held to less tolerance. That's very common in the industry.

The argument of holding tight tolerance is endless, with many suggesting that it's a waste of time, but the benefits often outweigh the cost in that once one learns to work to close tolerance, it takes very little time to do so and the small amount of time spent is often returned by the shorted time it takes for future operations. The real benefit is to the operator, who generally has increased machining skills due to the repeated training.

H
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rmac
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Re: Question for the No-DRO Crowd

Post by rmac »

Harold_V wrote: Edge finding on multiple sides can really complicate things because you may not be able to use the original data points as you pick up additional edges. That would certainly be true for using dials, although by recording each edge without changing the dial setting would work, but one must be quite comfortable with math to avoid making mistakes
Indeed. My lathe and mill both have 8 TPI lead screws, so while the conversion of a dimension from a given value to its "dial turns plus remainder" form isn't exactly higher math, it is tedious and prone to error. Starting with some non-zero dial setting and then trying to move backwards from there (turning the dials counterclocwise) would make it even more so.

-- Russell Mac
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tornitore45
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Re: Question for the No-DRO Crowd

Post by tornitore45 »

Talking about mental math. Since the early years in the lab it was a point of pride to beat the guy with the calculator.
Without feeling to brag I have exceptional mental arithmetic skill proven by comparison.
But in the shop is another story. There are too many things going on at the same time, to many distractions, to many factors competing for your
two-registers-brain and I do not trust the result to be committed to metal removal.
Out comes the calculator, I have two because one of the two is never to be found when needed.
Mauro Gaetano
in Austin TX
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rmac
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Re: Question for the No-DRO Crowd

Post by rmac »

Talking about calculators, I have an Amazon Echo in my shop, mostly for music. But I've found that Alexa also works as a great voice-activated calculator, even when the problem involves square roots or trig. I dunno how Siri compares, but I'd have to guess that it/she would also do the same sort of thing. Can somebody try it and report back?

-- Russell Mac
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tornitore45
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Re: Question for the No-DRO Crowd

Post by tornitore45 »

Siri, what is the cosine of 30 degrees? Answer 0.87 close enough
Siri, what is the square root of 4696? Answer Aprox 58.527
Mauro Gaetano
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Bill Shields
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Re: Question for the No-DRO Crowd

Post by Bill Shields »

Siri...how many people are listening to everything we say around the house?

123,456,789 too many
Too many things going on to bother listing them.
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liveaboard
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Re: Question for the No-DRO Crowd

Post by liveaboard »

Siri, how can I delete you from my computer?
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Steggy
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Re: Question for the No-DRO Crowd

Post by Steggy »

rmac wrote: Sat Jul 23, 2022 12:38 pmBut I've found that Alexa also works as a great voice-activated calculator...

She works even better as a snoop. You couldn't pay me to install one of those things anywhere in my home or shop. I value my privacy.
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Music isn’t at all difficult.  All you gotta do is play the right notes at the right time!  :D
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Steggy
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Re: Question for the No-DRO Crowd

Post by Steggy »

liveaboard wrote: Mon Jul 25, 2022 4:15 amSiri, how can I delete you from my computer?

All else fails, unplug it, take it out back and use your shotgun.
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Music isn’t at all difficult.  All you gotta do is play the right notes at the right time!  :D
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Bill Shields
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Re: Question for the No-DRO Crowd

Post by Bill Shields »

do you keep the voice activated remote for your Smart TV or cable box in a Faraday bag?

If not...it is still listening -> unless you plug the microphone with some super glue....
Too many things going on to bother listing them.
Rich_Carlstedt
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Re: Question for the No-DRO Crowd

Post by Rich_Carlstedt »

rmac wrote: Wed Jul 20, 2022 8:13 pm.....................This has to be something that was done millions of times before DROs came along. But how? Maybe with indicators mounted on the machine to eliminate the uncertainty due to backlash? Or maybe by setting stops to limit the table travel? Any hints? How would you "dials only" folks approach this? For the record, I'm also a "dials only" guy, but more due to circumstance than by choice.-- Russell Mac
Russell, I don't think anyone answered your question, at least this portion of it.
Maybe,my 65 years in shops can shed some light on Pre- DRO days
The "Primo" system to have ( which came out of WW II) was a "Optics system" and was available on Bridgeport's ( $$$$)
It came from use on Jig Borers and Jig Grinders and you had magnified boxes ( with light) on scales attached to the knee and table .
While accurate , It was a PITA in my opinion, and the last one I saw was scrapped in 1982 .
A more general application was to use multiple mag base dial Indicators (DI) , with strokes like 5 inches !
Using DI's has it issues, particularly if you accidentally move or hit one ---and lose the zero point
Another approach was to use Adjustable Parallel ( AP) gauges and hard stops .
You don't see folks using AP's much today, but they are wonderful tools as well as inspection gauges.
For instance, I have two sets, one top class for inspection and the other for tools and setting.
Here is an example , you drop a endmill or drill bit onto the work piece ( not turning) -clamp the quill
now you want to drill exactly . 666" deep..do you raise the knee ?, no you take your mike and set a AP to .666
then raise your Micrometer BP Quill Stop upward , but place the AP on the micrometer stop when it comes to the quill stop Knob .
Set the micrometer stop tight, and you now have a "certified" depth stop. You could count the turns and figure out how many
on the micrometer, but having a Mike set AP is far more accurate.. or I should say less error prone.
You also use AP between table stops for precise measurement

But here is something I never see guys do anymore - probably because of power-feeds which seems to be the detractor of precision
You eliminate backlash in the table feed Dials (!) by doing this
Use you left hand handle-wheel to only move the table from left to the right (!)
and the right hand side handle only moves table from right to left.
To remind you, take a magic marker and put a clockwise Arrow on the table endcap at both ends
now clamp the table lock and and turn the left handle clockwise (CW) until it stops (locks up) now "0" the dial
Repeat on the right side, turning CW until it stops, and set it 's dial to "0"
The difference in the dials is your backlash, but it is set by your dials
So say you drill a hole at 0 and the want to drill 2 more holes at 1.000" either side
Well to drill the right side hole , the right side handle ( moving table to the left ) is turned CW 5 times to '0"
And the to do the left side hole, the left side is turned 10 times CW and you bring it to "0" and you have exactly 3 holes at 1" spacing
and not backlash calculations

Oh, the old days

Rich
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Harold_V
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Re: Question for the No-DRO Crowd

Post by Harold_V »

Rich's comments for using both table dials was addressed by Gorton with their 9J mill by adding an additional handle on the face of the saddle which exited @ 45° on the right side. That made it a lot easier to use the second table handle, for mills with long tables made that rather uncomfortable due to the long distance between handles. The dual handle idea isn't very handy on long mill tables because you can't reach both dials comfortably.

I agree that working with long travel indicators on mills can be troublesome. The only time I did so was when I had to perform operations with taxing tolerances.

In retrospect, maybe that extra foot work on mills with long tables sans the angled handle was good exercise. :wink:

H
Wise people talk because they have something to say. Fools talk because they have to say something.
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