Machining Discussion-Lathes, Mills, CNC.

[freakmech]

well actually, i have every intention of turning manually, but as an investment... CNC might be a nice feature which doesnt cost that much more for the simple Sherline package. I would not go into something like this without learning the true art of it. Besides i think you need to understand how machining works in order to write code for CNC. All these machines can be used manually and thats where i plan to start. But should i produce something good i would like to be able to produce it on a larger scale for all modellers to use.

[redstang423]

Originally Posted by p9o1r1sche

Maybe its just me, but the tone of this thread made it sound like one needs CNC controls. Well, however its made, the quality will show in the final product.
Mike, you do some great scratchbuilding - more than I'm motivated to do. From that perspective, the CNC probably does help alot. Keep going on your project!

You definately do NOT need CNC to build model car parts. Its just very very useful if you are going to do mass production, or if you are doing a very complicated part. There are also some parts that just can't be machined with any accuracy without using a CNC machine (ex, some wheels).

Freakmech, you are definately right - it really helps to know how to do the stuff manually when developing the code. Keep in mind though, you generally don't actually write the code - you tell the software what you want, and it turns that into the code. You really don't want to even try to learn how to write in the code though - it is scary to look at.

[mike@af]

Originally Posted by redstang423

Keep in mind though, you generally don't actually write the code - you tell the software what you want, and it turns that into the code. You really don't want to even try to learn how to write in the code though - it is scary to look at.

Im going to have to disagree here. You need to learn how to write the programs. Its not as difficult as it sounds, designing the toolpathing is harder than writing the program. Without knowing the program functions, you can be in for costly mishaps. Verification, or not, mishaps still happen. Knowing the functions is a key part of CNC programming. I dont trust computers 100%. I'll use them to write the basic toolpath, and thats about it. From there I insert all the G and M functions to be safe. Let me put it this way, your mind knows what the computer needs to do more than that the computer knows.

EDIT: Ken, thanks for the kind remarks. About the CNC being "neccesary" to model is a false accusation, however its just the direction the thread has taken. CNC is an aid, and I can machine in both manual and CNC. Each has there place. Thanks for the interest. I do think that manual machining is more rewarding in a lot of aspects!

[gionc]

Originally Posted by GTmike400

Im going to have to disagree here. You need to learn how to write the programs. Its not as difficult as it sounds, designing the toolpathing is harder than writing the program. Without knowing the program functions, you can be in for costly mishaps. Verification, or not, mishaps still happen. Knowing the functions is a key part of CNC programming. I dont trust computers 100%. I'll use them to write the basic toolpath, and thats about it. From there I insert all the G and M functions to be safe. Let me put it this way, your mind knows what the computer needs to do more than that the computer knows.

Well: I have to fully agree with that: learn the basics....

BUT: I think we need a distinction: prototyping machines and CNC machines, every a mill, different approach. What you said Mike is abslotutely necessary for a CNC, heplpful on a prototyping mach. but non necessary. The only difference is that, proto machine have an "interpreter" who pick your 3d data and convert in its toolpathing w/out any needed from you than desired dyrection and bit diam./passes (res. level).
Basically the machine is the same, a mill linked to a pc.
I said that only to avoid to descourage "CNC newbee" like me to try: you need only to well know some nurbs or poligonal software.

Something more: in prototyping milling work're dead. A couple of other tecs. are now used: stereolytographt and syntherization. I look forward to contribute to that great discussion whit something which is used only to form resin or plastic shells, but where really isn't a "toolpath": only a 3d model and a prototype.

[redstang423]

Originally Posted by GTmike400

Im going to have to disagree here. You need to learn how to write the programs. Its not as difficult as it sounds, designing the toolpathing is harder than writing the program. Without knowing the program functions, you can be in for costly mishaps. Verification, or not, mishaps still happen. Knowing the functions is a key part of CNC programming. I dont trust computers 100%. I'll use them to write the basic toolpath, and thats about it. From there I insert all the G and M functions to be safe. Let me put it this way, your mind knows what the computer needs to do more than that the computer knows.

This might be have been true several years ago, but with the programs available today - especially the one I'm familiar with (GibbsCAM), its actually easier to design the toolpath than create the actual drawing. We have several classes in the engineering cirriculum at my college about manufacturing and machining, and all the professors have told us its really no longer nessecary to program with the actual code, and those who used CNC in industry hadn't programed using the code since the software started becoming popular. In that way, I don't have any real experience with writing code, but I have had no problems or close calls strictly using the software. As far as not trusting the computer, modern software goes through soooo many checks - especially $10,000 software that controls a $50,000 machine - there will not be "bugs." The only mistakes the computer will make will be those from the person who inputs the information. I'd trust a computer much more than me to correctly input hundreds of lines of code. You are definately correct in that you know what you need better than the computer - that is where the computer has its disadvantages if you don't know exactly what you are doing when designing the toolpath on the software package.

The other thing is think of it this way - while this doesn't have much of a bearing in car modeling, in industry, engineers will be making $30-50/hr or more. Its much more cost effective for the company if the engineer spends an hour using the software to build the toolpath rather than spending 4-5 hours writing the code.

[redstang423]

For an example - try writing the code for this without software. It would be hell. Everything done on the CNC machine from a SQUARE block of aluminum. Even the letters were cut by the CNC machine.



Now please don't take my posts the wrong way, I'm not trying come off as trying to say you are wrong. As I said, my experience is somewhat limited in terms of CNC program writing, so I might just be blessed with working with the top of the line programs that increases the ease of CNC programming ten-fold.

[gionc]

Well, gentlemen: I guess the spirit of that thread is to be helpful..
Also Mike thanks a lot for the link, its really helpful, however I like to ask something in a more "familiar" room.

So I start to ask. As said I'm really a novice in milling and turning.

I start to use my new hobby lathe, I done some experiment and I take confidence with a dozen of cutting tools, by the start they looks the same, now I know a little more. Well I found out some bugs, before all some samples:


-nearest I try to copy the Acu-stion stuff: shocks for the enzo, brass
-2nd a west-gate for my '80 cont. Lancia: I made 4 but I destroy 3in the mill for a bad alignement on the rotating table, and, as a great end, I broken my 1mm diam tool during an alignement operation, so the 4th is safe, , alu
-3rd water reservoir (I guess) every for my L. montecarlo, alu


Well I have a lot of questions, but'll like to ask step by step:

1:I've problem turning less than 1mm diam. on alu, quetly better on brass. Itry also at low speed, low increment of cut, no way. I lost a lot of cm of my alu.

2: I haven't a way to read the longitudinal (height of the part) movements: only way it's the gauge

3: I guess Acu-Stion used steel? I want alu for my parts, but I'm a bit frustrated, its no easy to turn a really soft material. Could I purchase some better alloy's metal like ergal? I want to turn really small parts: I'm a modeller (well I hope to become) not a carpenter.

Well if you agree I glad to use this thread to post my questions and show my crap in search of advice. Thanks a lot

[mike@af]

Turning extremely small parts on a lathe of that style will be difficult as they have a good bit of runout on them, anywhere between .005"-.020" (.1-.5mm). Plus there is some slop in the tool cross-slide and carriage. Thats probably why you are having a difficult time turning a diameter less that 1mm.

What tools are you using? Can you get a picture. That may be your problem with turning aluminum. I turn mostly aluminum, and a few brass bits here and there. The Acu-Stion parts look to be aluminum, which is what most aftermarket accesories are.

EDIT: To fix the slop and runout read up on that site I linked you to. The lathe you purchased is one of many often reffered to as a kit lathe because they require a complete rebuild to be accurate.

[klutz_100]

Originally Posted by gionc

I'm a modeller.... not a carpenter.

They look like a good start to me!!!

[gionc]

Originally Posted by GTmike400

Turning extremely small parts on a lathe of that style will be difficult as they have a good bit of runout on them, anywhere between .005"-.020" (.1-.5mm). Plus there is some slop in the tool cross-slide and carriage. Thats probably why you are having a difficult time turning a diameter less that 1mm.

What tools are you using? Can you get a picture. That may be your problem with turning aluminum. I turn mostly aluminum, and a few brass bits here and there. The Acu-Stion parts look to be aluminum, which is what most aftermarket accesories are.

EDIT: To fix the slop and runout read up on that site I linked you to. The lathe you purchased is one of many often reffered to as a kit lathe because they require a complete rebuild to be accurate.

I guess I express bad my trouble (my english is a crap): I havent a "gap" or other kind of problems (well, apparently), I achieve less than 1mm gap turning on the brass, but everytime I try on alloy it collaps, letterally collaps. Well I have an hard working day in front, lately I'll post some pics and try to host somewhere a little movie concerning the trouble, anyway thanks a lot.

Steve: really the pics ir quetly blurried, from naked eye those ir just a crap, and took me a lot of time. Not just a promenade.

[gionc]

Originally Posted by GTmike400

EDIT: To fix the slop and runout read up on that site I linked you to. The lathe you purchased is one of many often reffered to as a kit lathe because they require a complete rebuild to be accurate.

Well my desire was just have a "tour" and trying my new tool: you know, new toy, little cild , well its time now to follow advices: I'll do it.

[cinqster]

Originally Posted by gionc

Well my desire was just have a "tour" and trying my new tool: you know, new toy, little cild , well its time now to follow advices: I'll do it.

gionc,

I don't know if this will help as I've only had two days practice on mine so far and I've not done any really thin pieces yet!


Have you got cutting tools that are designed specifically for alluminium? I've bought some TC tipped tools that are only just OK but really for alluminium there shoud be a notch behind the cutting tip - I think it's to stop the stuff gumming up the tip. High RPM's and a cutting fluid (parrafin) may also help.

I'm not sure where Mike sent you but this one is THE most useful website I've found for the 7x12's - loads of advice on setting the beast up properly:

www.minilathe.com

[89audiQT]

well, here's a little information from my end, so take it as you will.

being as young as i am, i've never stopped learning things i've ever had an interest in. machining hasn't been an option yet, but i had built a DIY 2-axis (just X and Y, Z was controlled manually) CNC mill while i was in college.

There are alot of very detailed guides around the 'net that show how to build one with a dremel or rotozip-like tool. because of the nature of the project (and my course being in electrical engineering) i merely scratch built the motor controllers for the project. the rest of the thing was made out of legos and old vcr/floppy drive parts. once completed, it was capable of etching/engraving just about anything.

granted, it's not the best way to go, but in alot of cases, it gets the job done fine for things like wheels, flat or near flat body panels, etc. small details were a pain though and not worth the effort. and i mean small details, like smaller than lugnut details on a rim.

there are numerous programs available from sourceforge and universities alike, for free, that can transform anything from ZModeler files and Solid Works CAM exports, into vertex/3D line drawings, that will then control your home-built mill.

there is time and money involved, but, as an avid hobbyist in many areas, i plan on building a more complex one this coming summer. my targeted range for paying for everything, is roughly going to be in the neighborhood of $200 (USD) and should be able to knock out rims, brake disks (vented, slotted, and drilled), and other things of that nature.

it's really not as difficult as it sounds, and everything is so cheap, that replacing parts would just mean a short trip to a garage sale or maybe even your own garage for some junk parts, which alot of people just have laying around without knowing it.

anyway, when i can dig up some pictures of it and the pieces i created, maybe someone will find interest in it (short of spending $3000 for a table-top lathe or mill).

[klutz_100]

Originally Posted by 89audiQT

i merely scratch built the motor controllers for the project. the rest of the thing was made out of legos and old vcr/floppy drive parts. once completed, it was capable of etching/engraving just about anything.....
anyway, when i can dig up some pictures of it and the pieces i created, maybe someone will find interest in it (short of spending $3000 for a table-top lathe or mill).

Just Kidding

I'd LOVE to see that!!! Also, a thread on how you build your new one - a great idea

[mike@af]

Giovanni, if you cannot illustrate your problems through words, how about a few pictures of the problem? There a phrase, a picture is worth a thousand words, and everyone can understand pictures no matter what language they speak.