??? Making Setups

[Richard Carlstedt]

Ken, I know you wish to learn and that was the reason for the question so let me add a little more to the above which maybe will help.
Most Home Shop guys clamp things in a vise and think they have control...Nope !
One jaw is a Plane.. and when you look at 6DOF , the other jaw is a plane, but you really want a point .
When you have two opposing jaws ( ie planes) ...ONLY one is the master
Let me show you with a simple casting in a Vise

Note both the V Block and part are cocked when the vise jaws are closed ( 2 opposing Planes )

So realizing a Point should oppose the Plane we add a Dowel pin to act as the single point on the casting

Now this simple change has stabilized the part -the single point on the casting is opposed to the Plane
And this is for only 2 degrees of the 6 DOF , but it will accurately locate the part in that direction
We would need to restrict the other DOF to be perfect ( The above could not take side forces ie)

Rich
By the way, this is a huge subject...some guys spend their life on it
Edit was spelling error

 

[Canyonman]

Hi Rich, and Thank You!
--------------------------
Holy S##T!!!! I just Googled 6-DOF. It's Mindboggling!!!!

 

[tornitore45]

Much about machining can not be learned from a book, that is the reason experience count.
One learn from his errors and reflection of why a certain procedure failed.
Some set up are easy, clamp it hard in the vise and hog the heck out of it.
The challenge is when a higher degree of precision is required or the clamping is not as strong as an ideal situation.
The part is tin, flimsy, it stick out too much.
Under those conditions it helps to analyze how the cutter motion meets the part. Is it pushing it away? Sucking in in?
Is the cutter whacking a tin sheet side to side? Sometime mowing the cutter and the engagement arc of the cutter relative to the part can cut down vibrations. Sometime one has to sandwich a part and sometime machine a cradle to clamp it is the shape does not lend to clamping.
In substance every case is different, you look at the part shape, look at you many method of holding it, analyze the cutting force direction and come up with the best approach. If it fails in some respect you pause and reflect on the root cause of failure and learn to neutralize, then store the learning. That is what experience is.
Failure does not always need to be catastrophic, usually the set up is screaming at you saying "I am not happy".
If you are tuned in you will detect the impending catastrophe and stop. As you gain experience the you will find in a "pickle" less and less often and detect the need to stop readily.
A mistake can be a valuable learning opportunity.

 

[Cogsy]

Assuming the site is correct, here's what they say:
Identifier jigsandfixtures00haasgoog
Identifier-ark ark:/13960/t8rb7239fLccn 38014454
Openlibrary_edition OL6370621M
Openlibrary_work OL191913W
Pages 185
Possible copyright status NOT_IN_COPYRIGHT
I'm not suggesting taking/stealing someone's work but while you have to be careful, not everything on the internet is wrong or stolen.

I wasn't suggesting the link to the specific publication was breaching copyright, simply that the site itself is jam-packed full of material which is covered by copyright. Simply viewing the posted link will present the user with other "you may also be interested in..." materials which, depending on your browser history/cookies, may well be propagated with copyrighted material. So we don't post links to a site that hosts pirated material in large quantities, even if the link is to a legal copy.

I guess you consider it complying with the spirit of the law rather than the letter.

 

[alanganes]

As you can appreciate this is extremely expensive for the poor copyright holders yet the internet archive has vast resources. So if you don't mind screwing over the little guy, have at it, but please don't promote the site on the forum - it's a respect thing...

I have no interest in screwing over anyone. I have had some small stuff published in the past and realize how much work writing even a short article can be. Again, this book was published over 100 years ago by two authors who have loads of similar work in the public domain. They died over 50 years ago. It is a public domain book. The whole point of copyrighted material passing into the public domain is so that information and knowledge can be shared and not lost, while still allowing time for the authors/publishers a window of time to profit from their labor of producing it.

So far as I know, the Internet archive never pushes back against anyone making notice that their copyright is being violated there, they just take the stuff down. They are not a business, they are a non-profit that functions as a library and any works that are not public domain are there by permission and available only on an electronic loan basis to one person at a time, just like a physical library. It is nothing at all like a few other online book sites (one in particular whose name starts with "S"...) that are pretty blatantly piracy sites.

In this case, the original scan was done by Google Books and includes a specific cover page stating that the book is in the public domain.

You moderate the site and I'm fine with that. But please don't suggest that I "don't mind screwing over little the little guy" or that I lack respect for anyone. I would not have posted that if I did not know it to be a public domain work, and in fact did not post links to a one other work on the topic I came across for precisely that reason.

 

[elcid]

The book Jigs and Fixtures by Colvin and Haas might be a good read. Out of print now, I think, but it should turn up on Ebay periodically. Carr-Lane used to publish a book/manual on jigs and fixtures in support of the related products that they sell and may still do so.

The book is online at Jigs And Fixtures : Haas Lucian L. : Free Download, Borrow, and Streaming : Internet Archive
But copyright can be a minefield especially in todays digital world. What does "out of Copyright" Mean? (with picture)

 

[elcid]

I have pdf files of books that were downloaded years ago all out of copyright and free, what has happened since I downloaded them is copyright laws were revised and internet giants like Google who had told the world that they were digitising books so that people could read them for free in the future opened up a lucrative trade in copyrighting out of copyright books. Amazon has an old copy of the book Jigs and Fixtures for sale at less than £10, but also a reprint for around £50+. Google told us to monetise everything, everythng has a value.

 

[Canyonman]

Guys, My search for information on making "set-ups" was never an attempt at causing a dispute over copyrights. I am just trying to learn more on a subject which has caused me grief.
Ken

 

[clockworkcheval]

In my humble opinion the earlier mentioned books on jig and fixture design are a total overkill. It is unavoidable that those books give snippets of good ideas. However the majority of the content deals with how to achieve set-up for repeatable mass production. And we mostly are aiming at a reliable solid one-off set-up. And every once in a while a high-precision set-up. Highschool physics, practice and experience mostly suffice. Joe Pieczynski and some others give helpful insights.

 

[Steamchick]

Ken, I know you wish to learn and that was the reason for the question so let me add a little more to the above which maybe will help.
Most Home Shop guys clamp things in a vise and think they have control...Nope !
One jaw is a Plane.. and when you look at 6DOF , the other jaw is a plane, but you really want a point .
When you have two opposing jaws ( ie planes) ...ONLY one is the master
Let me show you with a simple casting in a Vise
View attachment 120681
Note both the V Block and part are cocked when the vise jaws are closed ( 2 opposing Planes )

So realizing a Point should oppose the Plane we add a Dowel pin to act as the single point on the casting
View attachment 120682
Now this simple change has stabilized the part -the single point on the casting is opposed to the Plane
And this is for only 2 degrees of the 6 DOF , but it will accurately locate the part in that direction
We would need to restrict the other DOF to be perfect ( The above could not take side forces ie)

Rich
By the way, this is a huge subject...some guys spend their life on it
Edit was spelling error

So basically, you advocate the first rule of stability = the 3-legged stool - as the starting point for a good set-up - presumably to resist the Major force of machining...?
I agree. BUT Please correct me if I am wrong in my understanding?
(The 3-legged stool only works in 2 degrees of freedom, remove gravity and you can't sit on it! - Ask a diver?).
K2

 

[clockworkcheval]

In a set-up for machining the force to counteract is not gravity but the cutting force. So you first and foremost have to determine the direction and strength of the cutting force.

 

[Ron Lunsford]

If I may just add another perspective do this conundrum... Understanding the order of operations to produce the needed item is the most important process to achieve the accuracy one may want. Take the time to look at the item needed and try to understand what each feature is used for and how can you manufacture each process without jeopardizing the next step needed to make the next feature... Sounds so simple but after SO many years of doing these things you start to develop an eye for how things can be held and or fixtured to make the desired feature. There are a great deal of solid advise logged here.
Kind Regards
Ron

 

[Cogsy]

So far as I know, the Internet archive never pushes back against anyone making notice that their copyright is being violated there, they just take the stuff down.

The internet archive supposedly considers itself a library and it holds many physical copies of books, both in copyright and out of copyright, which it digitally 'lends' to users. The way these digital copies are provided to users has long been a point of contention with publishers and copyright holders and there is strong belief that this is not a legal practice. Further to this, since the pandemic hit, they have gone beyond even their dubious legal practices and now 'lend' out an unlimited amount of copies, in excess of the number of physical copies they hold. They are now being sued over this practice (LINK). They are a non-profit but they do have substantial resources just the same and they are defending against the lawsuit. And they have not ceased this policy despite legitimate copyright holders asking them to.

 

[goldstar31]

Moving away from the Legion of lost Causes( My view), I've been 'briefing' one of our younger on collets and collet holders. He wants to regrind worn end mills and slot drills and whilst I have several dividing heads which are suitable, he hasn't. So I have suggested nothing more elaborate than a set of square blocks with tools held by flush grub screws and simply rotating them to profuce the 90 and 180 degree angles. Then I mentioned the intriguing too from Australia's Eccentric Engineering. Then I gave him the hint that the Late John Stevenson MBE RIP had simple blocks which are still available at Arceurotrade.
I have yet to inculcate him into the noble art of the GlueGun and a bit of 2 x 2 " scrap timber. Simply a great invention!
Thought that I'd bring things into the 20th or is it the 21St Century and not involve copyright time wasting

Regards

Norman

 

[KellisRJ]

Removed by poster.