Have no idea what I'm doing, but want to learn!

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To preface: I have absolutely NO idea what I'm doing when it comes to machining. Nothing. I have never even seen a machine shop. I have no idea about terminology, technique, or proper practices.

What I do have is an interest in learning a little bit, and figuring out how to adequately describe what I hope to accomplish at the end of all of this. And since I'm a complete and total newbie, I ask for a tad bit of forbearance and gentleness. I was reading on another forum (apparently for professional machinists, and they utterly reamed a guy to pieces for asking a simple question, and sadistically enjoyed doing it. That's just wrong, meanspirited, and uncalled for. We all were at a place once where we knew nothing, so please remember what that was like and remember that I don't already know what I'm doing. Thanks!

Now on to the fun part!

I am looking to describe two metal parts that I'd eventually like to get made, for a project I've been working on for a long time. Before I go any further, the nature of the project isn't relevant, nor is the final purpose for the metal parts relevant. ;) The reason I state this up front is, I've found that every time I try to describe the end result I'm looking for, everyone always stops thinking outside the box, and tells me that they can't do it, it won't work, it isn't possible, or it doesn't exist. I have found that if I just describe a thing in terms of what it's generalities are, and only give specifics where needed, I always arrive at the exact result I'm looking for. Process isn't relevant. End results are. So, describing what it is, and what it's going to be used for will change the way everyone thinks, and will prevent finding an efficient and workable solution. I have a lifetime of experience watching this happen over and over, and can give real, specific examples if asked to.

If these two metal parts were to be made out of wood, plastic, or any other material other than metal, it would be a very simple matter to describe them in very simple terms, and an even more simple matter to produce them at home, in the sanctity of the garage. However, in my research on metalworking, I've discovered that there is a significantly-greater demand for near-inhuman levels of precision. A brief example: if someone were to say to me, "I need a 1/4" hole in this thing, right about there" I would go to my garage, get a 1/4" drill bit, and drill the hole. From what I've found in the machinist's world, the hole has to be described to 0.0001" of precision both in terms of center-position and diameter. (slight exaggeration of numbers, sorry!).

Let me state up front that this kind of precision simply is neither required, nor necessary. I'm not making rocket parts! In my world, and for the purposes of this project, 1/64" of an inch is close enough.

I have a need for two small pieces of flat steel bar. I know there are hundreds, if not thousands of different alloys of steel, so this is one complicating issue for me. I don't know enough about how to accurately and adequately describe all the alloys, what they do, their properties, or anything about them. What I would like is a cheap, regular, plain steel that anyone can pick up anywhere, can be welded to a section of steel pipe I already have, and wouldn't cost a great deal. It doesn't have to be high-quality, rare-alloy, super-duper steel, just regular, plain, run-of-the-mill steel. Sorry for my ignorance. That's why I am here.

These two pieces will end up being 3-1/2" long (remember that I'm not dealing with microscopic measurements here) and 1" wide. One of them will be 1/4" thick, with one flat side, and the other will be 3/8" thick, with a rounded "groove" on one side. On the reverse side of both pieces are lengthwise grooves. They both have a matching set of 1/2" holes in them. Again, microscopic measurements aren't required.

My concern is, I don't know, or understand metalworking/machining terminology well enough to even begin to describe or even draw these shapes in terms that a hobbyist or even a professional shop would understand, because NASA-level precision simply isn't required. I think in entirely different terms, and I'd like to learn enough to describe what I am looking for, in terms that are understandable in this world.

I have attached a very rough sketch of these shapes, which should make things much more simple, for the sake of discussion. There are no dimensions, or descriptions, just a drawing of the shapes. I hope this is an adequate starting point, for me to learn how to accurately describe them in terms understandable to a hobbyist.

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My ultimate goal is to find someone who would be willing to make them, without me having to mortgage my house or sell my car to pay for them. I'm not Bill Gates.

Could I please start a discussion on how to detail these sketches to make them into drawings that could be used to actually make these pieces?

Thanks!
 
I like your question. You need to decide what is important. This is an issue of tolerancing. I can post more later but you could do some reading on the issue.
 
I don't want to throw gas on your fire, but the last time I did a job like you want with someone that said " that's close enough" I ended up putting in over 35 hours on a job that should have been done in 4. It only ended after I had enough of his " close enough revisions", and told him to find someone else. Of course I didn't get paid if you're wondering. From that point on if there's no print or dimensioned sketch, there's not going to be any work done.
 
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Those could eisily be made on a mill with common tooling.
Are you trying to learn how ro make these parts yourself?
If you want a machinist to make them for you, you just supply a blueprint or a drawings with dementions on it and let the machinist do what he does.
 
Some things do matter to you; I’m guessing you care that the grooves mate. So for that you might dimension from one peak to the next and designate that as typical.

Also the holes seem likely to allow relative motion of some parts? Allowing for sufficient tolerance on diameter means the holes can be drilled instead of also reamed or bored. That makes a big difference. If the holes are, say +-0.010 then someone reading the drawing knows they may be drilled.

The radiused back running along one of the parts looks to be the most difficult feature. Knowing the tolerance on radius is important. You said it would be welded to a pipe. I would think that a c-channel or a rectilinear recess rather than the radius would be better because it facilitates line contact for welding. But you don’t want that. Are you okay with the radius being more than that of the pipe? The tolerance will be driven by the tolerance of the pipe and your design considerations.
 
Welcome. We're easy going around here, no worries about being new.

Sounds like you want a mild steel. 1018 or similar should work unless you have have high heat or other stress in the application.

Your picture looks simple enough. I would add a drawing generated from the same CAD model with dimensions. Don't worry about the precision you don't need. Give nominal dimensions like 1.5" and a note on the sheet stating the tolerance. +/-0.005 is pretty common. 1/64 is about 0.015. If the part needs to fit inside something else, you might want +0/-0.005. You also need to specify the radius of the curved part and the angle of the slots. The slots look like a typical 90 degree V, but if you want someone to build it, you need to tell them what it is.

A pro shop probably won't want the bother to set up for two single unit parts. So they give a high price. A hobbyist might be willing to make them for a reasonable price. It won't be free though. Saw that with some people thinking 3D printed parts should be super cheap.

I'm curious about how people would cut that radius. A fly cutter held at 90 degrees might work... A very large ball nose end mill..

4ssss makes a good point. Machinists work to the drawings. We aren't generally artists and revisions cost. For a hobby job I would require payment up front and make it clear that if the part meets the stated tolerance, that transaction is complete. If you want changes, that's a whole new conversation.
 
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Could I please start a discussion on how to detail these sketches to make them into drawings that could be used to actually make these pieces?

All you need to do is add dimensions and tolerances. If the drawings aren't clear the machinist will let you know what they are unclear on.

The drawings you've posted thus far have me totally wondering what size they are. Are they 1/4" long? 4" long? 4 feet long?

Without dimensions on the drawing I have no idea what size these parts might be or whether I could even make them. If they are 4" long (or in that ballpark) I might be able to deal with them. If they are 1/4" long I really don't have tiny precision machines to deal with parts that small. If they are 4 feet long, again, I don't have machines to handle work that large. So until I see dimensions I have no clue what your parts are even like.

Edited to add:

Ok, never mind, I see you did call out demensions in the text. So they are in the 4" ballpark. That's certainly an easy size to work with. Almost any hobbyist should be able to deal with a project that size. The next question is do the grooves need to mate?
 
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I get why you didn’t want to post the final use or intention for the parts, but I think it could be a help. With the final goal in mind, someone might be able to think more outside the box. They might have a better idea of tolerances required, or might have suggestions on changes that could make he parts easier (cheaper) to make and accomplish the same goal. For instance, if the curved piece is just to fit the radius of the pipe and be welded on, farm fit might be good enough. The curve could be cut in steps with a small end mill and be good enough.
 
For instance, if the curved piece is just to fit the radius of the pipe and be welded on, farm fit might be good enough. The curve could be cut in steps with a small end mill and be good enough.

I was thinking the same thing. In fact, if it's going to be welded onto the pipe a simple V-grove would be just fine. Setting up to cut a perfectly matched radius would be a total waste of time.

In fact, I would draw in a v-groove in place of the radius and just mark it V-groove clearance for 3/4" diameter pipe (or whatever size pipe it will be welded to). That way the machinist could know how steep the V-groove needs to be based on the pipe diameter for best fit.
 
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When making parts that will are designed to be welded to something else it is best to include clearance for a good weld.
 
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