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

[Latinrascalrg1]

I didnt read all the replies, kinda stuck to the OPs posts so sorry if this has already been said....

I Think the part of the equation you are missing is A factor called "Tool Run Out." I think if you do some reading on this you will have a better understanding why machinist look for that "53 decimal" tolerance spec you spoke of.

 

[Ulma Doctor]

some folks are deathly afraid to mess things up.
i don't like to mess up, but i'm not afraid.

2 things happen when you mess up
1, you learn what not to do (or learn don't do that again)
2, you gain skills by rectifying the mistake, whether it is by remaking the part, or, by repairing the mistake- you do get smarter.

start small, make something seemingly trivial for a first project- but make it to the very best of your ability
when you are done, keep the trinket in a highly visible space in your shop so you can see your progression.

some of my first projects were tools and welding jigs,
maybe you could start by reproducing a 90° 1" square block from 1-1/8" material- similar to what the USN machinists do in their training program.
they only use a file to achieve the end dimensions and are highly inspected and scrutinized for dimensional accuracy

if you could do that, you could do anything you set your mind to

 

[ThinWoodsman]

At the risk of appearing a grumpy old man I get the distinct impression the OP would rather talk than do. Everyone here has given many versions of help and suggestions and the response is usually a "yeah but", "gee that's complicated", "I don't know how".

Eh, he's a teen-ager, their perspective of time is different. A project that takes a month seems like an eternity, but after a few decades a month passes by before you know it. I personally enjoy making parts by filing, but twenty-year-old me would not have put up with it. Sounds like he has enough to keep him occupied and let's face it, machining takes some time to learn just so you don't destroy the tools.

If I were to advise the original poster, I'd say that machining uses a lot of the same tools as woodworking: mills are routers, grinders are sanders, drills and saws are the same. The material is more hard so the tools must be harder, sharper, run at a lower speed, and able to withstand more torque (usually through rigidity). When submitting a spec to a machinist, you need to have all measurements from a reference surface (diameter or a rod, one side of a square, etc) and include as many decimal places as you think are necessary (in this case only two, e.g. for .25). When talking to an acquaintance who knows machining and metalworking, you can be much more informal, and say "a sleeve of 1/4" thickness to enclose a 2" diameter pipe, a hole 1/2" from the end" or something. Talk to somebody who's taken the shop class (do they still have those?) and see what you can work out.

 

[bhigdog]

The point is the lack of initiative. Other than playing with a computer was any attempt made to actually DO something towards accomplishing a goal? Were some attempts made at fashioning a crude prototype? The OP says the grooves were only a gripping surface. So..... a hacksaw or file would do the job.
64 posts and counting and nothing has been accomplished or even attempted. I'd bet my wallet most any 16 year old farm kid, a junk pile and a few common tools would have had a working example long before now and never once said "I don't know how".
My impression is the OP is fishing for someone to offer to make them for him................Bob

 

[Scootered]

Regarding your drill bit... It does not make a 0.5" hole. It makes a hole that is close to the right size. All drill bits do. You don't have the tools to measure it, but it's still there. Perhaps you don't care about the difference, but a machinist does. There are no perfect parts or features. The very best machinist or even CNC machines will have some error. It might be extremely small, but it's there. Thus, we have tolerances.

Well, I respectfully disagree.

I went out this morning to measure my pipe so I could have accurate info when I dimension my drawing, and I decided to test the bit. I took four different scraps of wood. Pallet wood (probably some cheap poplar or something), pine, maple, and red oak. Drilled a hole in each one. Measured those holes with every measuring implement I have. Guess what? They're all 1/2" holes. If there are any differences between any of them, my eye isn't good enough to see it (and nobody else's is either) and therefore it is a non-difference. That's enough precision for me in this project. I also took a piece of hard maple, and ran it on my lathe until it was 1/2" in diameter according to my measuring implements. It fit just barely into the hole. Couldn't get a hair in between, but it fit. Again, that's all the precision I need. That Forstner bit cost me a couple extra lawns mowed, so if it says it cuts a half-inch hole, and the holes it cuts measure a half-inch, then it's a half-inch bit. If it doesn't require any more precision than that, why worry about it? Seems like a waste of effort to me. Maybe I'm just too stupid to see it.

 

[Scootered]

At the risk of appearing a grumpy old man I get the distinct impression the OP would rather talk than do. Everyone here has given many versions of help and suggestions and the response is usually a "yeah but", "gee that's complicated", "I don't know how".
When I was a kid we made what we needed and improvised as required. Scooters were made from a length of 2 X 4, the wheels from an old roller skate, a wooden crate, and all held together with whatever we could find in the old man's garage. No one said "gee that's too hard". We learned by doing and we didn't have the internet with it's unlimited knowledge at our finger tips.
Every question that been asked of us has the answers readily available. Every process required can be duplicated with simple tools and devices found in the most basic home shop. Every attempt at making the parts will advance ones knowledge and skill base far more than asking about it.
I'd be far more interested helping someone who actually tried and was unsuccessful than one who just wanted tell me why he can't even try.




Yes you do......................Bob

Yep, you do sound like a grumpy old man. Doesn't seem to me like there's much I can learn from you, you know so much. In my opinion, not too much better than the people on that other forum who just love treating newbies like crap. So, I'll kindly ask you if you'll stay out of my thread, please.

 

[Scootered]

Eh, he's a teen-ager, their perspective of time is different. A project that takes a month seems like an eternity, but after a few decades a month passes by before you know it. I personally enjoy making parts by filing, but twenty-year-old me would not have put up with it. Sounds like he has enough to keep him occupied and let's face it, machining takes some time to learn just so you don't destroy the tools.

If I were to advise the original poster, I'd say that machining uses a lot of the same tools as woodworking: mills are routers, grinders are sanders, drills and saws are the same. The material is more hard so the tools must be harder, sharper, run at a lower speed, and able to withstand more torque (usually through rigidity). When submitting a spec to a machinist, you need to have all measurements from a reference surface (diameter or a rod, one side of a square, etc) and include as many decimal places as you think are necessary (in this case only two, e.g. for .25). When talking to an acquaintance who knows machining and metalworking, you can be much more informal, and say "a sleeve of 1/4" thickness to enclose a 2" diameter pipe, a hole 1/2" from the end" or something. Talk to somebody who's taken the shop class (do they still have those?) and see what you can work out.

I might only be 15, but I'm not an idiot, and I really don't appreciate the way that guy talked to me. He wouldn't take it coming from me, so why should I have to take it coming from him? This isn't ancient Rome where everyone had to pay obeisance and admire the "Pater" father figure.

You've actually given a very good explanation between the woodworking tools and the machine ones. My school cut out both the metal and wood shop four or five years ago because of budget cuts. So there's that avenue gone. I'm actually trying to learn something here. Contrary to popular opinion, you can't just get everything out of a book, or off the web. I don't learn that way. I have to see it. I have to physically go through the motions of doing it. I have to watch technique, how people move, and what their machines actually do. Drives some of my friends nuts, but I just don't learn that way.

I think that if I can get a drawing done in a particular way, that gets the point across that all the super-fine precision just isn't necessary, and as long as the final produced part looks exactly like the measurements on the drawing, and looks like the drawing, then it will be just fine. No hullaballoo about carrying things out to 47 decimal places.

 

[hman]

I kinda think many of us should lighten up a little bit. Scootered said he was absolutely new to all of this: "Nothing. I have never even seen a machine shop. I have no idea about terminology, technique, or proper practices." Also recall that he said, "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."

So let's back up a step or two, try to put ourselves in his shoes, and do what we can from there.

Scootered -
OK, Paint Shop Pro isn't a CAD program by any means, but you do seem to have the basic shapes drawn up. Dimensioning will be necessary when you want to show this to a machinist, and it's probably impossible on Paint Shop. But here's a trick I've used a time or two, that may get you where you need to be.

(1) First, you print out your creation. The example I'm doing is a screen shot from your first post. The "perspective" views are good for the overall concept, but if at all possible, you should include "face on" images from the face and the end, maybe even the side.
(2) Pencil in the dimensions, with tolerances. I've added a few (guesses) that I think are consistent with your posts. You need to give enough information to the machinist so he can build it. Where is each feature (generally with respect to one corner/face or other known feature of the part)? How big is the feature? Etc. A basic mechanical drawing/drafting book might be of use. But don't be intimidated by all the persnickerty details in anything beyond the first chapter or two. Your part is pretty basic.
(3) Scan the marked-up drawing back into your computer. Then you can make as many copies as needed, and have a record of the original.
(4) Take this along when you talk to machinists. Decide ahead of time that the purpose of the first such visit will be more educational than anything else. Let them know that you're not using a real CAD program. Thenlisten to the suggestions that they make. Have a second copy of the drawing in your hand, and make notes on it. Thank them for their time.
(5) Correct your drawing, per the suggestion of the first visit. Then either return to the same machinist, or go to some others.

Having a dimensioned drawing is pretty much vital to the process. As some others have pointed out, the actual machining is not an interactive process. You give the drawing to the machinist, then go away and wait for him to let you know the part is ready.

Errors? If the part is not made per the drawing, you can ask for a correction or re-do. If it's per print, you own the result. And again (as we've all done time after time), learn from your mistakes.

Best wishes!

 

[MarkM]

I ll tell ya what. I like the fact you put yourself out there and want to learn. I guess I am half old grumpy maybe? Doesn t matter I want to help you and would like to encourage you. We are on your side. Maybe we or I need to step up as I am half old and grumpy. You have your life ahead of you and we all would like you to be successful so I thinks it s best to enc ourage you and throw everything out above and take it all with a grain of salt. I will help you! I ll donate some time and material. Now from you all I ask is to try. Forget cad/cam and your computer for this project. Learn the basic skills. It will make you better at cad/cam. It s much better to struggle to understand something then to just get the answer. When you troubleshoot those basic skills come to surface.
Let s pretend you walk in my shop tomorrow and would like me to (Remember It s a shop that put s food on the table) do some work for you. Don t touch your computer. Were doing this old school. Grab a pencil and a pc. Of paper and do your best to draw a top view and a side view. We ll go from there. I am a mile from the Maine border so no big deal to send it to you.
Put it on paper. Take a pic. And post. We could all help or if you d rather send me a private message but I may learn something too! so how do feel about putting the picture in the thread. You already showed you have courage!
.Here is some chicken scratch. A very rough scetch but just to give you an idea. Something like this I can go and cut my material. No math to work out for spacing and depth of cuts. Time cost money.

 

[FanMan]

Others have talked about needing drawings so I won't add to that except to agree that yes, you need a drawing if you want a machinist to talk to you about it.

Tolerances: Not something you worry about with woodworking, but with metalworking it's important. Your half inch hole: Most drills cut slightly oversize. If you use your Forstner bit to drill a half inch hole, it'll be a half inch plus a little. It's not your eyes that can't tell the difference, you probably don't have measuring tools accurate enough (most woodworkers don't). But because that half inch hole is probably a bit oversize, your half inch dowel will slip into it... though it may be a bit tight so you have to tap it in. But wood is forgiving.

Now take a half inch hole in metal. Say you dimension it as such, .500 diameter. Typical hole tolerances might be plus or minus five thousandths (±.005). Say your hole comes in undersize at .495 (.500-.005). You want to put a bolt into it that comes in a bit oversize at .505. No way it's gonna fit even with a BIG hammer. To avoid that, you dimension the hole a bit oversize, a typical drilled hole for a bolt will be 1/64-1/32 (.016-.031) oversize. That's what you need to specify on your drawing, not just 1/2". Going oversize on the holes also allows for the holes being slightly out of position, i.e. if they don't quite line up the bolt will still fit through the overlap area. On the other hand, if you make the holes too oversize, the fit may be too sloppy causing other problems. Since none of us here know what your final intended use is, there's no way we can advise you on what an appropriate fit or tolerance would be. But if you specify too-tight tolerances, it's going to cost you more.