# Hard aluminum Vs. mild steel?



## Twmaster

While reading a couple of threads here and elsewhere recently the comments were made about a good hard grade of aluminum being a suitable substitute for mild steel. The aluminum mentioned specifically in one post was 6061-T6.

I've made more than a few parts out of 1018 CRS and am now wondering if the 6061 I have in stock would indeed be suitable. Some of the parts I make are tool posts and holders for small benchtop lathes.

Some illumination would be great.

Thanks!


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## Lew_Merrick_PE

Twmaster  said:
			
		

> While reading a couple of threads here and elsewhere recently the comments were made about a good hard grade of aluminum being a suitable substitute for mild steel. The aluminum mentioned specifically in one post was 6061-T6.
> 
> I've made more than a few parts out of 1018 CRS and am now wondering if the 6061 I have in stock would indeed be suitable. Some of the parts I make are tool posts and holders for small benchtop lathes.



AL 6061-T6(xxx) and most low carbon merchant steels (C1015-C1020) will have very comparable yield and ultimate tensile strengths. If that is all you need to worry about, then weight and cost will be your deciding factors. However, steel has (roughly) 3X the tensile, shear, and tangent modulus of AL 6061-T6(xxx) aluminum. That means that, for any given cross-section of the part, steel with be 3X more rigid than aluminum. More importantly (at least from my knothole as a design and development engineer), steel will "fight deformation" 3X harder than aluminum when you cross over the yield point as it stretches towards ultimate failure.

Additionally, steel will have a significantly greater shear stress capability than aluminum. This means that you get nearly 5X as much carrying capacity in a given thread engagement in steel as you do aluminum. This is the difference between a body-centered cubic crystal structure (LC steel) and a close packed hexagonal structure (aluminum). Anodizing aluminum will bring their properties in this regard closer (about a 2.2:1 advantage to steel). Unscaled merchant steel will have (about) 4X the (resistance to penetration) surface hardness of (6061-T6(xxx)) non-anodized aluminum.

Although most people consider this counter-intuitive, aluminum will wear out (unhardened) steel in sliding wear. Bare aluminum oxidizes quite thoroughly. Aluminum oxide is one of the very common abrasives used. Anodizing will reduce this somewhat, but only somewhat. In most instances, a sulfuric anodize is really as good as a "hard (chromic) anodize." The hard chomic anodize will flake off with impacts whereas the sulfuric anodize will deform.

Weight is the final factor. 6061-T6(xxx) aluminum has a density of .098 lb/in³. Most low carbon steels have a density in the .282 to .285 lb/in³ range.

My designation "T6(xxx)" has to do with process specific treatments of aluminum. When it is solution heat treated to the T6 condition, most of your material properties are fully defined there. When given a stress-relief cycle after treating, it becomes "T651" temper. If you do a straightening process thereafter, it becomes a "T6511" temper. If you start with a "T6" bar or plate, it is generally worthwhile to heat it in an oven to (about) 450°F (20 minutes + 10 minutes/inch of thickness) and let it cool in the oven. Let it sit for at least 3 days before machining to allow the temper to fully reassert itself. You should not have to do this with either "T651" or "T6511" tempers unless you are trying to hold a parallelism value less than .0015 in/6 inches of length or width.

Does this help?


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## Tin Falcon

> I've made more than a few parts out of 1018 CRS and am now wondering if the 6061 I have in stock would indeed be suitable. Some of the parts I make are tool posts and holders for small benchtop lathes.


TW:
A2ZCNC http://www.a2zcnc.com/machinetools.asp produces commercial tool posts and holders for small bench lathes. They are a scaled down version of the Aloris. I copied the specs below . As you can see they use 6061 -T6. I have one of there tool holder sets and love it . I have made aluminum tool holders for it and plan on making more holders and tool posts like it, Out of aluminum . In my humble opinion use what you have and move forward . It is a proven design and a proven material. Anodizing would be a nice addition but not mandatory. 
Tin 


> # Quick Change Tool Post Two dovetails so you can switch from turning to boring/facing without any tools or changes to your setup
> # QCTP machined from billet 6061 T6 Aluminum
> # Hard Anodized for durability and appearance
> # No tools required to change bits
> # Versions to fit Sherline, Taig, Unimat, Atlas and 7x10-12, 9x20 and most small lathes
> # Additional tool holders available
> # Inline handle for added strength
> # Optional 1/2" boring holder available
> 
> Additional Holders & Accessories:
> Standard stick tool holder
> 3/8" boring bar holder
> 1/2" boring bar holder
> 1" x 1" silver blank holder
> cut off blade holder
> USA made .040 x 1/2" cut off blade
> See a review at www.Mini-Lathe.com


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## kf2qd

In my opinion - 6061 is rather soft - I would like to build a toolpost out of 7075.


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## doc1955

I beg to differ 1018 shear strength is not 3x 6061 t651

1018 = Tensile Strength, Yield 380 MPa 55100 psi 
6061 t651 = Tensile Strength, 324 MPa, 47000 psi
7075 t651 = Tensile Strength, 572 MPa, 83000 psi

3X ?


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## Deanofid

Mike, have a look at the Speedy Metals website. They have material properties charts for most 
everything they sell. 
For instance, 6061/T651 is shown at 45k (psi) tensile and 40k yield.
1018 CRS shows just about double on both those numbers. 
7075 shows numbers about equivalent to 1018, and has a similar Brinell hardness. That last
part may make a difference to you if surface deformations are an issue over much softer 6011
when choosing an aluminum alloy over steel for something like a tool post.

I know you have a market in mind for some of the things you make. Material may be a consideration
purely from a marketing viewpoint, all other things being equal, including end price. For instance,
I would buy a tool post made of steel before I would buy one made from aluminum. Even if the
seller put in goonball kickers like "aircraft aluminum" or the common "billet" misnomer. 
That's just me, of course.

Maybe trying a poll here would give you some good info from an actual market group. People 
here buy this kind of product. Asking "Would you rather have product X in steel or aluminum?"
may give you some insight for the buyer preference. 

I understand you want to use stock you have on hand. That makes sense. It would be prudent
to give it a good, hard workout if it's something like a tool post. Threaded holes in it are going to
see a lot of use, and tool slots take a lot of pressure. 

Dean


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## walnotr

I worked with aluminum aircraft for most of my adult life and have to say there are good things and bad things about 6061-T6. Very seldom will it be used for a structural part on an aircraft unless it must be welded or is used to carry fluids. It is not used for structural elements. There are many other alloys far superior. That said, I have been using quite a bit of it for my projects lately although nothing I do is industrial or life sustaining. All metals have good and bad properties and the best bet is to research and see which is the best match for the application at hand. You want large and light? Use aluminum. Building a steam locomotive? Steel would probably be my choice but you can bet every pound saved by using aluminum in non-critical areas would go a long way towards getting a ton of freight 450 miles on a gallon of fuel.  There is a reason aluminum is one of the most used metals on earth (and not just because of beer cans).

Bottom line, use what meets the needs of the design. My 2 cents.

Steve C.


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## Lew_Merrick_PE

doc1955  said:
			
		

> I beg to differ 1018 shear strength is not 3x 6061 t651
> 
> 1018 = Tensile Strength, Yield 380 MPa 55100 psi
> 6061 t651 = Tensile Strength, 324 MPa, 47000 psi
> 7075 t651 = Tensile Strength, 572 MPa, 83000 psi
> 
> 3X ?


Doc, you are citing *typical* Tensile Yield Stresses (engineers *must* design to *minimums*), *not* Allowable Shear Stresses. Aluminum has a more pronounced "grain" than steel and is more sensitive to cross-grain loads. This is especially true when it comes to inter-crystalline loading known as "shear." The question was posed as to the relative functionality of low carbon steel versus 6061-T6 aluminum. 7075-T6(xxx) and 2024-T4(xxx) aluminums have a modified close-packed hexagonal crystal structure that is closer to the body centered cubic structure of steel and, hence, have higher relative shear strength values.

Aerospace engineering manuals have good information, but the presentation assumes a rather broad background in metallurgy. The old American Society for Tooling and Manufacturing Engineering (ASTME -- the forerunner of the Society for Manufacturing Engineering -- SME) had really good explanations as to the different types of stress in their _Manual of Blanking and Forming Dies_. Finding a copy is hard (try used engineering book stores), but definitely worth the effort if this interests you.

One of my engineering professors used to say, "You need to go back to the beginning of a technology before the _priesthood_ was established as that was the time when people were *communicating* information rather than proving *why* their need to be priests." This is why the old texts tend to be so good.


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## Tin Falcon

Lew: while your dissertation here is informative lets not forget the original question can 6061 T-6 be used successfully for tool holders for a small bench lathe. The answer is yes. will other material be stronger and last longer again yes.
Here are a few I made the factory made one is in the middle. 





TW not building a space shuttle nor is he attempting to launch himself in a rocket from his Texas ranch. He just wants make a few tool holders for a hobby lathe. 
The old Chinese proverb comes to mind " Those who say it can not be done please do not disturb those who are doing it. 

Tin


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## doc1955

Tin Falcon  said:
			
		

> The old Chinese proverb comes to mind " Those who say it can not be done please do not disturb those who are doing it.



I like this and have to second it!


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## steamer

7075 T6 is what I made the con rods in my engine out of and it has held up fine.

I would think for home shop, any of the solution heat treated aluminums ( The "T" portion of the number) would work fine in a toolholder application....not so much from the strength perspective which is irrelevent here. But from the wear perspective.

A toolpost will fail from being not rigid enough to give a good finish, long before EVER reaching its tensile or yield strength. What may defeat these parts, long term, is wear.  In industry....absolutely, they'll wear out in short order.....in the home shop...not so much.....tools YOU make tend to get pampered more than others.....and the lathes that are in use are low power compared to industry.

Have at it...post pictures!

Dave


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## Lew_Merrick_PE

Tin Falcon  said:
			
		

> Lew: while your dissertation here is informative lets not forget the original question can 6061 T-6 be used successfully for tool holders for a small bench lathe. The answer is yes. will other material be stronger and last longer again yes.



Tin,

If you go back to my original posting, my statement was that, if ultimate and yield tensile strengths are your only criteria, then cost and weight are the factors determining which you use. However, aluminum and steel are *not* equal in all areas and there *are* real and valid differences between them. It is also important to consider the finish you are going to give them. It is important that those in the "trade" know more than merely the ultimate and yield tensile strengths (most of my metallurgy was learned as an apprentice machinist).

*My* "database entries" for metals include: minimum allowable ultimate and yield tensile stress, minimum allowable shear stress, tensile modulus, bulk modulus, shear modulus, tangent or secant modulus, elongation, impact strength, fatigue factors, coefficient of thermal expansion, density, and machinability. While the tensile or secant modulus rarely impact "home shop" types, they should be understood by all who work in the "trade." Knowledge and skill are what set us apart.


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## Cedge

Hey Lew....
I've been watching your comments to various threads and I'm curious. Do you now or have you ever worked for Microsoft's tech support? I ask because in each post you've furnished highly technical and excruciatingly correct information which contributes almost nothing to the original poster's questions. While expertise is to be valued, I've yet to see anything you've made with all that knowledge. 

This forum is of, by and for amateur hobby machinists who build small marvels with limited abilities, knowledge and unlimited determination. We most often get our mystery metals from scrap yards and lucky finds. In short, we work with what we have and do minor miracles with it. Show us your bona fides in some real work before you begin lording your superior knowledge over us lesser mortals. Whats in YOUR shop?....eh?

Steve


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## doc1955

Cedge  said:
			
		

> Hey Lew....
> I've been watching your comments to various threads and I'm curious. Do you now or have you ever worked for Microsoft's tech support? I ask because in each post you've furnished highly technical and excruciatingly correct information which contributes almost nothing to the original poster's questions. While expertise is to be valued, I've yet to see anything you've made with all that knowledge.
> 
> This forum is of, by and for amateur hobby machinists who build small marvels with limited abilities, knowledge and unlimited determination. We most often get our mystery metals from scrap yards and lucky finds. In short, we work with what we have and do minor miracles with it. Show us your bona fides in some real work before you begin lording your superior knowledge over us lesser mortals. Whats in YOUR shop?....eh?
> 
> Steve



I can't help but second this!


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## Lew_Merrick_PE

Cedge  said:
			
		

> Hey Lew....
> I've been watching your comments to various threads and I'm curious. Do you now or have you ever worked for Microsoft's tech support? I ask because in each post you've furnished highly technical and excruciatingly correct information which contributes almost nothing to the original poster's questions. While expertise is to be valued, I've yet to see anything you've made with all that knowledge.
> 
> This forum is of, by and for amateur hobby machinists who build small marvels with limited abilities, knowledge and unlimited determination. We most often get our mystery metals from scrap yards and lucky finds. In short, we work with what we have and do minor miracles with it. Show us your bona fides in some real work before you begin lording your superior knowledge over us lesser mortals. Whats in YOUR shop?....eh?
> 
> Steve



No, I've only worked for Microsoft doing mechanical and manufacturing design engineering.

Let's see, I started my apprenticeship as a tool & die maker in 1967. I hold my journeyman's rating through the German Machinist's Guild (passed it on my fifth try). I have worked on a contract basis most of my life and done work for more than 350 different companies and government agencies. If the schedule does not change, there's a Mars lander that will be launched in late-August or early-September which will be steered between here and Mars using a fuel pump system I designed and built back in 2006-2007. I did most of the hand work developing stratofied charge fuel systems while at the Vehicle Research Institute (DoT) back in the mid-1970's.

The question posed here was, "Is aluminum equivalent to steel property-wise." Too many answers focused solely on yield and ultimate tensile strength. This was something I thought needed clarification. I find it interesting that you claim I am "lording my superior knowledge over (you) lessor mortals." I think of more along the lines of *sharing* those things I have been lucky enough to find courtesy of those who shared their knowledge and skills with *me*.

A) I have not yet figured out (not really having the time) how to post pictures. It seems I need to post them someplace else and give a "link" to them. B) A significant portion of the work I do is either "proprietary" or "classified." I have posted a couple of (PDF) "project documents" and reference documents in the files section here. I try to be a "giving" member of the community. Among my recent projects are: designing and building automated and semi-automated tooling for the production of solar power cells; designing and building a laser scanning system for medical analysis; designing and building an alternative system for dialysis; and designing and building a tidal power generating system. That covers most of the past six months. If you would rather that I leave this forum, just say so.


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## dsquire

Lew

I would very much hope that you *do not* leave this forum or the HMEM group. I have learned so much from reading your posts and want to continue to read and learn.

If a person only wants a yes or no answer than they may not want to learn. If they do want to learn and that is why most people come to this forum then they will appreciate the detailed information that you have given.

I look forward to your continued participation in these forums. :bow: :bow:

cheers 

Don


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## cidrontmg

dsquire  said:
			
		

> Lew
> 
> I would very much hope that you *do not* leave this forum or the HMEM group. I have learned so much from reading your posts and want to continue to read and learn.
> 
> If a person only wants a yes or no answer than they may not want to learn. If they do want to learn and that is why most people come to this forum then they will appreciate the detailed information that you have given.
> 
> I look forward to your continued participation in these forums. :bow: :bow:
> 
> cheers
> 
> Don



I second that.


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## capjak

Hi Lew,

Please stay with us. A good number of your posts are way over my head but there is always some bit of information that I can use. If some people don't care to read your posts, all that they have to do is use the scroll wheel on the mouse or the back button in the upper left corner of the screen.

Jack


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## Tin Falcon

> If you would rather that I leave this forum, just say so.


Lew we are asking that you consider the audience and post in clear concise language. We want you to encourage the members in there endeavors. We want to see pictures of your home shop models and projects . we are not looking for you divulge trade secrets or jeopardize national security. Normally photos are posted to a hosting sight like photobucket then a link is posted in the thread on this forum. 
Tin


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## Cedge

Lew
Staying or leaving is a choice you'll have to make all by yourself. I'm sure you're quite knowledgeable, but the condescending tone is both abrasive and to some extent insulting to those of us who are building at the best of our ability. Take off the starched shirt and tie....get your hands dirty. It's about the only road to earning your chops with this group. 

I'm sure the projects were both impressive and important, but here it's model engineering, where the numbers get so small that the tables aren't a whole lot of help. The stresses are such that we can cheat the numbers and still come out on the winning sideof the event. Just unwind a bit and be "one of the guys" for god sake. We don't care what letters you string behind your name and titles are just in the way here.

Steve


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## Maryak

My 2 Bob's worth,

Lew,

You have beyond any shadow of doubt demonstrated an amazing grasp of a vast range of highly technical facts and figures. This has obviously impressed some of our members and not others.

Your climb from humble beginnings as an apprentice tool and die maker to the dizzy heights of aerospace engineering is to be admired.

Now really impress me by 1. learning how to post a picture
                  2. Making a model engine or showing me one you have made.

Best Regards
Bob


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## steamer

Lew,

One Engineer to another....and I've been doing it a long time... I do understand what your saying.  And at some level, your right, it all matters.

But give me a brief moment of professional courteously.......and hear me out.

( By the way, there are a LOT of Engineers who are members here)

As Steve said....just throttle back to a regular guy......we could use your experience here....it can't hurt and we'll ALL learn something.

Let me tell you about this place......as I'm neither a moderator nor a high achiever here. Perhaps you'll appreciate the perspective.

This place is a well mannered bunch who in general will open a personal vein to show how human we are. We LOVE to help each other with problems.  We're not one of those "other" sites that judges and grades, we like to have fun and be creative....and lord knows there is TONS of creativity and genius on this board. I'm befuddled daily with some othe creations that get posted!

I count these people as my friends....and I would like to think they think the same of me.

I have yet to meet anyone on this board who has not learned something from it. I* doubt I'll be proven otherwise.* Hang around and have a bit of fun.....I'd be glad you did. I think you would too.

There....and there ends my off topic commentary....steping carefully off the soap box.......OK!  anybody want to talk about aluminum? ;D


Sincerely,
Dave


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## Twmaster

Great googly moogly!

First, Um, wow. What a mess I've made. T'was not my intention.

I want to thank all of you for your input. Yup, even you Lew. Even though most of your comments went waaaay over my head I still appreciate that you took the time to reply.

I did see the answers I was hoping to see. Simple yes and no is not what I sought and I was not let down. There's more than enough info to keep me reading for quite a bit.

In summary, nope, not building any space hardware. Although if my efforts to rebuild my lathe encounter any more snags some parts might just make it into low earth orbit as I see just how far a huge angry man can toss said parts.

Basically I have an idea for a tool post. It's not something I currently make. (Yes Dean, those other parts will continue in 1018CRS)

I wish to prototype it is hard aluminum as that is what I have in stock and can afford to burn if when I screw something up.

I hope none of you have any sore feelings toward anybody. Life's too short for all that.


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## Deanofid

Not knowing exactly what you're making, Mike, I'd say just turn out a prototype with what you have
on hand and give it a workout. Practical engineering is a great teacher, and you can prove the end product
in your own shop. Most everyone here is a practical engineer, and for us, there's no other way to know
what will break until we break it.

I was originally _guessing_ that you may intend to change something you already make. The main thing I
thought about was customer complaints by way of component failure due to a change in your materials.

(If you're making something for the 618, send me one and I'll be glad to try to break it for you. Consider
me a no charge test lab..)  

Dean


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## Twmaster

Heh, OK Dean, I'll keep you in mind as a beta tester. While not specifically for the 618 I expect it to be compatible.


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## Artie

Im with Dean, I have heaps of "oops, that didnt work" prototypes laying around...each taught me something and many have been recycled over the years.... tis never time wasted.. although it may seem so at the time... ;D

Artie of the prototype pile :-\


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## steamer

Artie  said:
			
		

> Artie of the prototype pile :-\



Hey Artie....you have one of those piles too?  ;D

Dave


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## tel

Don't we all?


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## Artie

yes Dave I got a beauty... ;D

On this subject, on another thread I made comment on using brass for the low load tool holders (boring bars etc)... Im just gonna do it and report in when I have news.... gotta use that brass up somehow.....

Gday mountain man... cold up there tonight?

R


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## tel

Yeah, cold enough, but not as bad as it has been - bit of cloud keeping the frost off.


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## Stan

Mike: Several times I have posted replies and even pictures of the tool holders (not tool post) made out of 6061 T6. They have stood up well on a 10" Logan and being very much an amateur, they have have received a lot of abuse.

Separate from the aluminum question, I am surprised that you use 1018 CRS with all the machineability and warping problems people talk about.


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## Philjoe5

Ive been reading this thread with much interest. I've used 6061 and 7075 series aluminum alloys in model building and the 7075 I have is a joy to work with. It machines beautifully, is harder than 6061 and can be had for about the same price.

Now, as to making toolpost holders. Check out this set sold by a most reputable vendor in our hobby, Little Machine Shop.

http://www.littlemachineshop.com/products/product_view.php?view=classic&ProductID=2461

These are anodized for durability, but they are commercially available from 6061 T6 aluminum. Its been done

Cheers,
Phil


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## arc100

I saw a few posts by a guest called Lew_Merrick_PE. Does anyone know how I can email or get in contact with this guy?


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## dsquire

arc100 said:


> I saw a few posts by a guest called Lew_Merrick_PE. Does anyone know how I can email or get in contact with this guy?



Lew is a member of http://madmodder.net and can be found there.

Cheers 

Don


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## Entropy455

Several months ago I also received a personal message from aboard moderator asking me to &#8220;Please tone it down a little on the high tech jargon&#8221;

The topic of discussion was how to home stress-relieve a weldment. A recommendation was made to blast the part with a rose bud for a few minutes until it glows red, then let it cool. The problem is that stress relieving requires precise elevated temperature controls for many hours &#8211; as well as a controlled rate of cool down. I.E. blasting the part with a rose bud would likely introduce far more stress, then simply machining it in the as-welded condition.

Needless to say, my recommendation to &#8220;farm-out&#8221; the stress relieving process &#8211; while made with the best intentions - was not well received by at least one moderator on these boards.

I am a Mechanical Engineer, licensed in the state of Washington. My job is to help maintain propulsion systems on nuclear powered warships. Where I work, we have hundreds of machinists, and thousands of mechanics. It never ceases to amaze me at the amount of &#8220;bad blood&#8221; that exists between engineers and machinists. Engineers are viewed by machinists assmart-a$$ punks, who are overpaid, and don&#8217;t know anything. Machinists are viewed by engineers as grumpy mean guys who will not give anyone the time of day &#8211; and will get flat-out angry when you ask them a question.

Engineering school taught me a lot, however it did not teach me the tricks of the trade for operating a milling machine or a lathe. I&#8217;ve become good friends now with several of the machinists at work. All I did was ask them - what&#8217;s the best way to reduce chatter, or what&#8217;s the best way to get a better surface finish with this end-mill, or how do I get the cutting tool to do this . . . Point being, it was only after they realized that I was an engineer who was taking a personal interest in their trade, that I was treated with some level of respect.

When someone takes the time register a username and password on these boards, and makes a post that contains technical information &#8211; why not assume that it was done so with the best of intentions? Why must some folks on these boards immediately go on the offensive and challenge credentials, or ask to see pictures of a workshop? Why not simply ask for clarification on the posting, in lieu of going on the attack?

Here&#8217;s my two cents:

I would not use aluminum to construct a tool post holder. Justification: The Young&#8217;s Modulus for aluminum is about 1/3 that of steel. The Young&#8217;s Modulus is the &#8220;rubber-band-ness&#8221; of a metal. The lower the Young&#8217;s Modulus number, the more the metal will deflect with a given force. Thus a tool post holder made of steel (or cast iron) will deflect three times less than one made of aluminum. This means that steel will provide a more rigid foundation for the cutting tool - thus more consistent cuts under load. This is a big reason why metal working machines are usually made of cast iron, and not cast aluminum. . .

FWIW, Lew said the same exact thing in the third sentence of his original post to this thread (he just did so with less words, using more traditional engineering verbiage). He went on further to explain how steel has more distortion energy, and its grain structure gives it a greater resistance to shear. His post provided ALL required information needed to make an educated decision on whether or not to construct a tool post out of aluminum. I don'tbelieve he did a copy-and-paste from the internet, as Lew did not talk about the poor cyclical fatigue properties of aluminum with respect to the endurance limit. He specifically did not mention cyclical fatigue, because it&#8217;s not applicable in a tool post holder application.

Lew&#8217;s initial comments were not condescending. The way I see it, it was folks on these boards who put Lew on the defensive by challenged his credentials, asking to see pictures of his workshop, taunting him for not knowing how to post a picture, and implying that his post is somehow discredited if he can&#8217;t post a picture of a model engine that he&#8217;s already built.

Again - It never ceases to amaze me at the amount of &#8220;bad blood&#8221; that exists between engineers and machinists. . . . .


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## arc100

Entropy455 said:


> Several months ago I also received a personal message from aboard moderator asking me to Please tone it down a little on the high tech jargon
> 
> The topic of discussion was how to home stress-relieve a weldment. A recommendation was made to blast the part with a rose bud for a few minutes until it glows red, then let it cool. The problem is that stress relieving requires precise elevated temperature controls for many hours  as well as a controlled rate of cool down. I.E. blasting the part with a rose bud would likely introduce far more stress, then simply machining it in the as-welded condition.
> 
> Needless to say, my recommendation to farm-out the stress relieving process  while made with the best intentions - was not well received by at least one moderator on these boards.
> 
> I am a Mechanical Engineer, licensed in the state of Washington. My job is to help maintain propulsion systems on nuclear powered warships. Where I work, we have hundreds of machinists, and thousands of mechanics. It never ceases to amaze me at the amount of bad blood that exists between engineers and machinists. Engineers are viewed by machinists assmart-a$$ punks, who are overpaid, and dont know anything. Machinists are viewed by engineers as grumpy mean guys who will not give anyone the time of day  and will get flat-out angry when you ask them a question.
> 
> Engineering school taught me a lot, however it did not teach me the tricks of the trade for operating a milling machine or a lathe. Ive become good friends now with several of the machinists at work. All I did was ask them - whats the best way to reduce chatter, or whats the best way to get a better surface finish with this end-mill, or how do I get the cutting tool to do this . . . Point being, it was only after they realized that I was an engineer who was taking a personal interest in their trade, that I was treated with some level of respect.
> 
> When someone takes the time register a username and password on these boards, and makes a post that contains technical information  why not assume that it was done so with the best of intentions? Why must some folks on these boards immediately go on the offensive and challenge credentials, or ask to see pictures of a workshop? Why not simply ask for clarification on the posting, in lieu of going on the attack?
> 
> Heres my two cents:
> 
> I would not use aluminum to construct a tool post holder. Justification: The Youngs Modulus for aluminum is about 1/3 that of steel. The Youngs Modulus is the rubber-band-ness of a metal. The lower the Youngs Modulus number, the more the metal will deflect with a given force. Thus a tool post holder made of steel (or cast iron) will deflect three times less than one made of aluminum. This means that steel will provide a more rigid foundation for the cutting tool - thus more consistent cuts under load. This is a big reason why metal working machines are usually made of cast iron, and not cast aluminum. . .
> 
> FWIW, Lew said the same exact thing in the third sentence of his original post to this thread (he just did so with less words, using more traditional engineering verbiage). He went on further to explain how steel has more distortion energy, and its grain structure gives it a greater resistance to shear. His post provided ALL required information needed to make an educated decision on whether or not to construct a tool post out of aluminum. I don'tbelieve he did a copy-and-paste from the internet, as Lew did not talk about the poor cyclical fatigue properties of aluminum with respect to the endurance limit. He specifically did not mention cyclical fatigue, because its not applicable in a tool post holder application.
> 
> Lews initial comments were not condescending. The way I see it, it was folks on these boards who put Lew on the defensive by challenged his credentials, asking to see pictures of his workshop, taunting him for not knowing how to post a picture, and implying that his post is somehow discredited if he cant post a picture of a model engine that hes already built.
> 
> Again - It never ceases to amaze me at the amount of bad blood that exists between engineers and machinists. . . . .


 

I feel your fustrations. Probably not on the same tech level as you but same situation. I'm not a qualified mechanical engineer or machinist, however I do quiet well in my job and hobby involving both types of skills. I'm the only tech guy in the company so I have to build whatever I design. Most of my work is for basic automated filling machines, packaging machines and class 3 solvents. Some of the guys on the production floor seem to think I'm trying to belittle them when trying to ask questions about operations and techniques and problems that arise during machine operations. Some day I hope to buy my own 4-axis CNC mill. (VMC) 

I myself think of you guys in highest regard more so as generous people rather than for the tech skills you have. Simply because you guys are giving advice and your time on these forums for free. There seem to be a fair few people in this world that are highly educated in a field of expertise and I do notice a bit of arrogance among them as if they are a higher class of human being. Idk, maybe it's just people in general, everybody these days seems to have to be someone important in order to be worthy of breathing fresh air or something. I just like learning tech stuff as a hobby plus it helps me a lot at work as well as with my race karts.

Anyway, I got in touch with Lew and I will be in touch with you too. Lew is a great guy and a real life "rocket scientist". Which is a bit of buzz to speak to someone who works on space craft. Maybe it's common in the USA with such a big space program. But here in Australia not so much.

Regards
Mark.


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## Maryak

Hi Guys,

Just so you don't die wondering, the moderator concerned was me.

Having started life as a deck hand on a prawn trawler, I did end up with a degree in engineering having first worked my way up from the workshop floor as an apprentice fitter and turner; and I stand by my, what were until now, private comments, made at the time.

Best Regards
Bob


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## gus

Philjoe5 said:


> I&#8217;ve been reading this thread with much interest. I've used 6061 and 7075 series aluminum alloys in model building and the 7075 I have is a joy to work with. It machines beautifully, is harder than 6061 and can be had for about the same price.
> 
> Now, as to making toolpost holders. Check out this set sold by a most reputable vendor in our hobby, Little Machine Shop.
> 
> http://www.littlemachineshop.com/products/product_view.php?view=classic&ProductID=2461
> 
> These are anodized for durability, but they are commercially available from 6061 T6 aluminum. It&#8217;s been done
> 
> Cheers,
> Phil



I would have used aluminium if I could get the suitable grade.So I took a deep breathe and jumped in used ground M.S. bars. Using  dovetail miller cutter is something very new to me. Quick Change tool post can be very expensive.So I make mine for US$10 for tool post and 6 tool bit holders.Local bought Proxxon tool holders cost US$99.95 w/o freight cost and its made in PR CHINA!!!
Best to take heavier cuts with dovetail end mill to avoid rubbing instead of cutting. Fixed steady is also homemade. Bronze hollow disc was left-over from job making spoked fylwheels.
I am glad I chose steel which stood up very well .Parting tool holder also home made.However I did buy LMS holder on offer at US$19.95.

Gus.


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## Busydad

I have tool holders made of both mild steel and 6061t6 pieces. The only thing i have found is if the mounting hole is a close fit in an aluminum holder the top of the hole can be deformed over repeated use , i have fitted steel bushings with a large washer type top to spread the load ..  I am no machinist , a diesel mechanic for 11  years and for the last 16 a long haul truck driver..I appreciate any input with regards to materials and tool selection..I have many OOPs for lack of the proper information..Discussion both pro and con is one of the reasons that i enjoy these forums..The wealth of knowledge that the members here is great and always helpful...


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## gus

Busydad said:


> I have tool holders made of both mild steel and 6061t6 pieces. The only thing i have found is if the mounting hole is a close fit in an aluminum holder the top of the hole can be deformed over repeated use , i have fitted steel bushings with a large washer type top to spread the load ..  I am no machinist , a diesel mechanic for 11  years and for the last 16 a long haul truck driver..I appreciate any input with regards to materials and tool selection..I have many OOPs for lack of the proper information..Discussion both pro and con is one of the reasons that i enjoy these forums..The wealth of knowledge that the members here is great and always helpful...



Hi BusyDad,
While cutting dovetails for my very first QCTP,I was tempted to use hard aluminium which easier to cut but not as wear resistant as steel and went steel instead and very happy I made the right choice.
The fine dusty chips do get in but easliy brushed off and the steel tool holders
still in good shape after 12 months usage.
Upgraded with a better version DIY QCTP with six tool holders.See attached foto.


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