saying hello with a couple of questions

[JonC]

Hey guys.. I have spent the beter part of two weeks reading here.. ALOT of information for sure.. way to much for a newbie to absorb.. I have a couple of questions.. Hope some will take the time to point a guy in the right direction..

One of my hobbies is building custom computers.. I have spent a ton of money on "custom cut" pieces in lexan, acrylic and aluminum..

Finally I started looking around at prices for a "cheap" cnc router.. then....I stumbled onto this site.. after reading and reading.. I am ready to attempt to build my own CNC router..

I have never seen one.. muchless used one.. I want something that I can custom cut lexan, acrylic and aluminum.. actually I can see a entire new hobby starting here.. lol


I have looked at all of the great projects here.. and believe that I have come up with the beginings of a design..


I do have a couple of questions..


where can I buy the high molecular plastic ( sorry .. do not know the real name for it ) .. from what I have read .. it is very strong.. and has less give than aluminum..


I see that alot of people choose a "rail" system verses the "t-bar" system.. is there a reason for this.. cost.. strength... ?


I am a little bit mixed up about the software that I will need..

I have read alot about some software named mach2 or 3..

I guess I dont understand the process.. I design something in Mach2.. then what..? I am clueless..

please help...

[JonC]

I am looking to build a "modified" version of this machine..

[Al_The_Man]

Originally Posted by JonC where can I buy the high molecular plastic ( sorry .. do not know the real name for it ) .. from what I have read .. it is very strong.. and has less give than aluminum.. ..

Did you want this to machine or to make a machine from?
There is one I use quite a bit that has several usefull properties. Including very nice to machine. = Phenolic.
This is one write up on it.

PROPERTIES
Excellent dielectric strength
Good machinability
Light weight
Heat and wear resistant
Resists corrosion and chemicals
Good mechanical strength & dimensional stability
Low moisture absorption

APPLICATIONS
Terminal boards
Switches
Bearings
Gears
Wear strips
Gaskets
Washers
Transformers
Machining components
Industrial laminates

Phenolic sheet is a hard, dense material made by applying heat and pressure to layers of paper or glass cloth impregnated with synthetic resin. These layers of laminations are usually of cellulose paper, cotton fabrics, synthetic yarn fabrics, glass fabrics or unwoven fabrics. When heat and pressure are applied to the layers, a chemical reaction (polymerization) transforms the layers into a high-pressure thermosetting industrial laminated plastic.
Al.

[JonC]

I was thinking of making the machine from this material..

[Al_The_Man]

Probabally be ideal, but expensive?
Al.

[JonC]

I havent been able to find this material anywhere..

My initial thoughts are to build the majority of it using 1" material.. is that enough..? or overkill..

being very new to this.. I am eager to build my own machine.. and learn how to use it.. but a couple of the decisions in the begining are crutual..
thank you for taking the time to help

[Al_The_Man]

If you live in or near a large town, look in the yellow pages for Plastics suppliers, They can show you all kinds of plastic products and give you the qualities etc.
Most large towns have them.
1" would be considered very heavy duty for Phenolic.
Al.

[ger21]

UHMW plastic (ultra high molecular weight) is nowhere near as stiff as aluminum. As Al said, about the stiffest plastic is phenolic, and it probably costs more than aluminum.
If you want to cut aluminum thicker than 1/8", you'll need a pretty solid machine, unless you want to take a lot of very light passes.

Mach3 is a machine controller. You need a CAD program to design your parts. Mach3 comes with a simple CAM program, LazyCAM, to convert your designs to g-code that Mach3 will read. For more complex parts you may need a more advanced CAM program.
www.artofcnc.ca

[JonC]

I appreciate the replies..
Thanks to your help.. I believe I have found a vendor to buy the product from..



I am going to take the advise of many here.. and start small.. I plan on my first table to have a operating surface of 12" x 24 "..



I was thinking of utilizing a dual t-bar set up for all axis'

is there any advantage or disadvantage of t-bar verses a rail system..

[ger21]

What do you mean by T-bar?

[wizard]

Originally Posted by JonC Hey guys.. I have spent the beter part of two weeks reading here.. ALOT of information for sure.. way to much for a newbie to absorb.. I have a couple of questions.. Hope some will take the time to point a guy in the right direction..

We will point you but only you can determine the right direction!

One of my hobbies is building custom computers.. I have spent a ton of money on "custom cut" pieces in lexan, acrylic and aluminum.. Finally I started looking around at prices for a "cheap" cnc router.. then....I stumbled onto this site.. after reading and reading.. I am ready to attempt to build my own CNC router..

Several things happen once you consider machining metals like aluminum. One is coolant usage, maybe you will maybe you won't but coolant can impact many materials used to make simple routers. Once you consider machining metal you might as well consider making the machine out of metal.

I have never seen one.. muchless used one.. I want something that I can custom cut lexan, acrylic and aluminum.. actually I can see a entire new hobby starting here.. lol

Yep and a whole new path for your money to leave your hands.

I have looked at all of the great projects here.. and believe that I have come up with the beginings of a design..

Due to time and other issues I think about designs alot. Actually implementing them is another issue.

If you have never done machine tool builds before there is a learning curve. Don't let that stop you though, just don't go overboard on the machine that you first learn to do all of this stuff. That is seriously consider making one cheaper limited capability machine first, to get a handle on building and the mechanics behind these things.

If you do have tool building experience or machine shop experience then you may want to plunge ahead.

I do have a couple of questions..

By the time you are done you will have had hundreds so this is a good start.

where can I buy the high molecular plastic ( sorry .. do not know the real name for it ) .. from what I have read .. it is very strong.. and has less give than aluminum..

From a plastics store. Seriously most larger cities have a supplier of plastics just like they have a steel supplier. That is one avenue, try to become familiar with some of the suppliers below:
McMaster-Carr
MSC
Travers
Enco

None of the above are cheap but they catalog just about everything. It also surprised me to no end how fast they can get the oddest order to you, especially McMaster and MSC. There are other suppliers that cover the US, I've worked iwth McMaster and to a lesser extent with MSC for a very long time.

Do consider local tooling and machining supply houses. These would be more regional or possibly single site operations. Especially consider local suppliers for raw materials, such as steel, plastic and bearings.

Then there is E-Bay, used equipment dealers and auctions.

I see that alot of people choose a "rail" system verses the "t-bar" system.. is there a reason for this.. cost.. strength... ?

Sadly I'm lsot as to what you are talking about. The only T-Bars I know about are at the beach.

So we need to work on this a bit. I'm thinking you are talking about linear bearings. But then agian it might be the table.

I am a little bit mixed up about the software that I will need..

To run the machine you will need software to interpet the NC code and drive the machine. One common platform for this is EMC. EMC runs on a variant of Linux and is a open platform. The best approach to installing EMC is to get the BDI (Brain Dead Install) distribution. This pust a copy of EMC and Linux onto your computer.

I have read alot about some software named mach2 or 3..

This is another platform for executing NC code. Some people like it?
[/quote]
I guess I dont understand the process.. I design something in Mach2.. then what..? I am clueless..
[/quote]
Not at all like that Mach or EMC execute a computer program written in NC code (commonly called G-Code) to move the axis to make the parts. By the way Mach and EMC aren't the only players for low cost NC control, just wanted to point that out before you come to the wrong conclusion.

In any event to generate a part you need the G-code program that provides information for movement of machine axis. There are a number of ways to generate this code.
1.
Do it by hand. Not impossible and if the NC controll is used for odd things the only practicle approach. However for the machining of simple parts it is not reccomended. Atleast not until after you learn some basics of G-Code.

2.
Generate a CAD file describing the parts and then generate a G-code file from that CAD file. This often requires a CAD program and a progrma to translate the CAD file into a G-CODE file that will produce the part.

3.
Use a programming lanquage/translator like APT to generate G-code from a text description of the part.

4.
Use a program that generates G-Code from an image file such as a bit map or JPEG. This approach is often used by people that like to engrave immages into wood.

5.
Write a program of you own that calculates the tool path for odd geometries. This requires experience in one or more programming languages and G-Code. An approach like this is prety advance but does have applications for the hobbiest. In industry such programs are often used with the metrology system so that elements of the programm can be tweaked based on the results of critical parameter measurement. Usefull when simple tool offsets are not usable. Maybe a little much for the hobbiest.

please help...

Well if no one has scared you off there certainly are enough people here to help. I would reccomend though getting a book that covers CNC and maybe one that covers machining and machine shop practice. If you get into this deeply you will need reference material.

Since it sounds like you have limited exposure to machine tools I'd suggest that you consider a small to very small router first to get up to speed on the technolgy and the basics of machining. I wouldn't even think aobut metal at this point. If that goes well then you can move on to a bigger machine.

Related to the exposure issue I'd suggest taking in a model engineering show or two. This to look at the end results and also if you are lucky to get input about machine tools. Also considering the items that you described that you want to make it may be beneficial to think seriously aobut buying an imported minimill and converting it to CNC. It maight actually be cheaper and will likely be the easy path to machining Aluminum well. There are a number of web resources with respect to the conversion of imported Mills. I'd still make a cheap and small CNC router first for the learning experience. After that you should have a good idea about which machine would fullfill your needs best, a large router or a NC conversion of a imported Mill. I bring the imported mill up because of your interest in doing Aluminum, as this is the easy path to a simple and rigid CNC machine.

Thanks
Dave

[ViperTX]

Personally....unless you have a bunch of time and enjoy designing and building stuff....I would recommend that you purchase a pre-built unit. Buying is the quickest way to get some return on your investment.