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  #11  
Old 03-02-2019, 04:37 PM
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LKeithR LKeithR is offline
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Once you spend a bit of time in a machine shop you will begin to see the difference in precision between wood and steel. Most woodworking projects are lucky if they're made to a 1/16" tolerance; high precision might be 1/32". The standard unit of measure for a machinist is .001"; many orders of magnitude smaller than even 1/32 of an inch.

Essentially that's just the way it is; the way that measuring machined parts has evolved over time. So many machined parts are designed to fit together with very close tolerances: pins in holes, pistons and rods in hydraulic cylinders, pistons in engines, crankshaft to bearing fits in compressors and motors. None of these parts would work if the closest a machinist could make the fit was 1/32 of an inch.

If you spend some time watching Youtube videos, reading and also talking to other people you'll soon begin to see the value--actually the need for tight tolerances. In any case that's the way it is and if you can't learn to comprehend the machinists way of doing things you'll never get a project like this off the ground. I have every confidence that you will but it's up to you to make the effort to learn and understand what you need to know.

The first thing I would do is buy a set of cheap 6" digital calipers. Learn to use them and start measuring things around you and you'll soon see the value of being able to measure in very small increments.

As to your question about the hardness of steel consider this. You're right in that all steel is 'hard' but there are varying levels of hardness. A piece of ordinary mild steel can easily be cut with even a cheap file but there are steels available that can be hardened to the point that the best of files will only skate across the surface when you try to file it.

Stay with it. You will learn. You'll learn a lot. You're young so you have a whole lifetime in which to figure this all out. Just remember that even us old farts who have been doing this for years still find ourselves learning new things on a regular basis. And the best part is that are many of us on this and other forums who would love to mentor someone like you. All you need to do is spend a lot of time listening and asking the right questions...
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  #12  
Old 03-02-2019, 04:48 PM
Scootered Scootered is offline
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Quote:
Originally Posted by LKeithR View Post
If you've modeled the parts as shown in your picture then you should have a supporting drawing that shows dimensions and details--most machine shops would need nothing more in order to make them. You really don't need to "describe" the parts unless you want to tell people what they will be used for.
I haven't really "modeled" anything. I just drew them in a graphics program. It's not a CAD thing or engineering thing at all.

And my use of the word "described" is really me not knowing the terminology you guys use. To me a "description" contains important details that might not be readily obvious on first inspection.

Quote:

It is the "use" more than anything else that will determine what material should be used. If you can't disclose that information because you're making something "secret" then it's going to be a lot more difficult to get others to help you determine the best material for the job. In the end, though, it should be possible to figure out what you need.
It isn't a "Secret" and it isn't a matter of me wanting to hide anything. Let me tell you a short story.

A couple of years ago, I went into a big-box hardware store, looking for some parts for a Halloween costume. I started out explaining exactly what I was doing, what the costume was, and I showed pictures to the guy in the store, and he told me they didn't have anything like what I wanted. So I went to two other stores trying to find the pieces I needed. What I was trying to do was attach one tube of fabric to another tube of fabric in a way that it could come off and snap back on. After a half-dozen explanations, I gave up trying to find what I wanted. A few days later, I was visiting a friend in another city, and tried the hardware stores there. Except this time, I wouldn't tell anyone what it was for. Just that I was trying to attach a glove to the sleeve of a big jacket where it could come off and be put back on. A plumbing guy showed me this 4" black corrugated drain pipe, and the fittings for matching downspouts, and those were the exact parts I needed. When he asked me afterward what I was doing, I told him they were for an astronaut costume, and I was attaching the glove to the suit. When I had told everyone up front what I was doing, they stopped thinking about what parts could work, and started focusing on real astronaut suits and how they worked. They quit thinking outside the box. When I told that last guy only the bit about how I was trying to attach one cloth tube to another, the snap fittings on the plastic drain pipe became evident to him. Ended up winning the costume contest.

So if I give too much detail, everyone will focus on the end thing, and not pay any attention to the two little pieces that will be doing the job.

Quote:

I suspect the "other" forum" you were talking about was Practical Machinist. Don't give up on them. They can be a bit harsh at times but collectively there is an absolutely huge pool of knowledge just waiting for you to tap into it. Some of the smartest professional machinists in the world hang out there.

If you want to visit PM--and you definitely should pose your questions over there--read and understand the rules and stick to them when posting. Most of the "newbies" who get burned on PM either don't read the rules or don't abide by them. They'll also tend to come across some times with a little too much swagger in their tone. Give them as much detail as you can in your first post including pictures and a description of what you're looking for. Be as clear and precise as possible and, above all, be patient and you'll find that you you'll get a lot in return...
To be honest, I don't remember what the name of the place was, but I do remember that everyone was just openly hateful. I also noticed that nobody really read what the original guy posted, but chimed in on what they thought he wanted, and reamed him a new one for being a "stupid newbie" The one thing I learned from that forum was that I needed a hobbyist machinist, not a professional. Hence, why I'm here.

Trust me, if I tell you what I'm going to end up making, everyone will worry about that, instead of just these two little bitty parts of it.
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  #13  
Old 03-02-2019, 04:52 PM
Scootered Scootered is offline
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Originally Posted by greywynd View Post
You’ve described and sketched it well. Is this something that you are looking for a set for yourself, or larger volumes to resell?

Are the ‘grooves’ a particular profile?

I can think of a few ways to make parts like in your picture, the methods would depend on whether I’m making a pair, or 200 pair of them.

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I'm just looking to figure out how to describe these things the right way so that if I actually took as drawing to a local machine shop, I could get them made pretty cheaply. No, the grooves aren't really anything special. The ones I made out of pallet wood just had a little triangular groove in them because I have a small router bit that did it like I wanted. The sketch I drew is pretty close to what it really looks like. I figured if I posted a picture of the wooden ones, it would cause more problems than it would solve.

I'll probably have to save up a good bit of money to pay for it, but I've got a friend who's dad is a welder, and so the welding part is already taken care of. Just need these two metal pieces to put on the pipe I've already got. This thing is a great idea, and I'm surprised I've never seen anything else like it. There's a story behind this, and its a good one.

I promise, once I get it finished, and if it works like I think it will, I'll come back and post pictures, or maybe a link to a video and show everyone.
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  #14  
Old 03-02-2019, 05:02 PM
Scootered Scootered is offline
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Originally Posted by Norm W View Post
Your post said, "Project Discussion." The drawings were great but without knowing what they are for, limits discussion of types of steel, possible improvements in design and machining methods. More information, would mean more discussion, which would mean more information for you.
Respectfully, my personal experience with many, many little tasks like this one is the exact opposite of what you've said. When I give people any more details than just the absolute barest minimum, they all stop thinking about what would work, and instead think of how to improve the overall final thing. I've seen the exact same thing happen over and over again. Even here, a couple of people stopped reading the entire post I wrote, and only responded to part of it, not answering what I asked, but what they thought I wanted.

All anyone needs to really know, is that I need two pieces of steel in the shape of the sketches I posted. Steel is steel. Unless it's some surgical-quality stainless stuff, or high-strength aerospace stuff, plain old regular steel will do the job. Heck, China even makes shovels out of plain steel sheets. There used to be a factory not far from where my grandfather lived that made hatchet heads for another company. They got steel rods by the truckload. I've even got a bunch of little pieces of it that my granddad picked up for free.

I'll give up one more bit of info about how it's going to be used. It will be clamped around a smallish (less than 1-1/2") piece of wood, and tightened down with a 3/8" bolt and wingnut on either side. So, a plain steel would be fine, as it isn't going to be used on anything but a little piece of wood.

If you'll forgive me for asking the obvious, how does any of that help me figure out how to put measurements on my drawing that make any sense to anyone other than me?
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  #15  
Old 03-02-2019, 05:14 PM
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Ironman Ironman is offline
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We can help here and one guy here does great things with smartdraw.
I think you will find people helpful but they like to be able to and with more info they can.
Like you just said
Quote:
It will be clamped around a smallish (less than 1-1/2") piece of wood, and tightened down with a 3/8" bolt and wingnut on either side. So, a plain steel would be fine, as it isn't going to be used on anything but a little piece of wood.
This tells me plain old mild steel will be fine. And now we know the curvature of the arc on one jaw. I'll call them jaws because they look like vise jaws.

So two of your answers are: it's called mild steel, and the curved surface will be expressed as degrees of arc of a circle sized X

Quote:
It will be clamped around a smallish (less than 1-1/2") piece of wood, and tightened down with a 3/8" bolt and wingnut on either side. So, a plain steel would be fine, as it isn't going to be used on anything but a little piece of wood.
There are many hardness and wear abilities in steel. 4140 steel is one, AR plate is another 50050 is ball bearing steel.
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  #16  
Old 03-02-2019, 05:33 PM
Scootered Scootered is offline
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Quote:
Originally Posted by Ironman View Post
We can help here and one guy here does great things with smartdraw.
I think you will find people helpful but they like to be able to and with more info they can.
Like you just said

This tells me plain old mild steel will be fine. And now we know the curvature of the arc on one jaw. I'll call them jaws because they look like vise jaws.

So two of your answers are: it's called mild steel, and the curved surface will be expressed as degrees of arc of a circle sized X


There are many hardness and wear abilities in steel. 4140 steel is one, AR plate is another 50050 is ball bearing steel.

Yippee! I feel like I'm getting somewhere!

I know there are as many alloys as there are products that use them, but it's just so confusing for a neophyte to try to figure all this out, especially in a vacuum.

Let me play around in Paint Shop Pro, and see what I can come up with based on the lessons I've already learned here.

Thank you!!
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  #17  
Old 03-02-2019, 05:55 PM
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midmosandblasting midmosandblasting is offline
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Look forward to you being around . I have done a lot ,worked as engineering tech several years . These guys on SFt have become friends.I learn a lot listening to their projects ,.When it comes picture time please post as a attachment not off sight host.
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  #18  
Old 03-02-2019, 06:07 PM
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Whitetrash Whitetrash is offline
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I'm just throwing this out for discussion. But, do these pieces have to be steel? You might be able to use aluminum and rough in the curved side with a router. Then finish it with a file and save the cost of machining.
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  #19  
Old 03-02-2019, 06:20 PM
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GWIZ GWIZ is offline
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Quote:
Originally Posted by Scootered View Post

Could I please start a discussion on how to describe these pieces in a way that they not only make sense to a machinist,
but are correctly and properly detailed so that someone could make them if they chose to? That would, ultimately, be the goal. Finding someone to make them for me!

Thanks!!
That is what I was doing.


Quote:
Originally Posted by GWIZ View Post
Say the face side has 60deg V grooves 1/16" deep (serration's) that are cut length wise.
A machinist needs that info.

Quote:
Originally Posted by Scootered View Post
Way too complicated. The way I drew them, I created a polyline at right angles, and extruded it. Then I cut off one edge and then mirrored the whole thing. And in the grand scheme of things, I really don't think it would matter whether there are "half points" or not. This is not rocket engine parts, and there is no need for NASA level precision.

:
A machinist needs information to find out if special cutters will be needed and purchased.

A serrated slab cutter can range two grand. and cut each plate in 10 minutes "not including setting up the machine".

in your case a machinist may grind a single point 60deg cutter and cut each groove one at a time. figure 3-4 hours for 4 plates.

With the more information that you posted, that radius would have set you back another 3-4hrs.
with your new information you don't need a radius, just weld the pipe onto the plate, or if you must. have a V groove cut in the back side it will be a lot faster and cheaper than cutting a radius. A slot would be cheaper yet.
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  #20  
Old 03-02-2019, 06:38 PM
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Originally Posted by Scootered View Post
China even makes shovels out of plain steel sheets.
Likely the crap ones.
If a steel shovel does not have a higher carbon level and "hardened" the shovel will fold up like a noodle the first time you tried to step on it to get it into the ground.
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