2 or 3 axis Brideport

[slowbob]

Hi,

My cousin is looking for a CNC mill to replace his aging brideport with a CNC. Because I own a couple Emco F1’s I was his first stop on getting some information.

One of the things that came up is 2 or 3 axis? My F1’s are 3 and 4 axis machines. I'm self taught on CNC and don't have any real machine shop experience. For the life of me other than for plasma I can’t think why one would want a 2 axis CNC mill. Do you wait for the mill to complete a circuit and manually lower the quill?

Also, maybe I should post this part of the question to the software forum, but he has found one with Prototrak control/sw. I do my work in GMAX or AutoCAD and create my toolpaths with Meshcam, Cnctoolkit or CamBam. If I need a conversational program I use New Fangled Wizard add on for Mach3. I see there are translation programs to convert DWG or DXF’s to Prototrak is this expensive and or difficult to learn?


Thanks in advance,
Bob

[TOTALLYRC]

I used a 2 axis mill to just drill repetive holes in part to be fixtured up in the big machining center. It is good for slotting and other 2 axis profiling, you just have to move the quill by hand. Don't know on the other part of your question.

If you cut it twice and it is still too short, what are you waiting for. cut it again, you are bound to get it right eventually.LOL

[MrWild]

Long time ago computers and controls were silly expensive compared to the iron. We were slowly going away from manual mills and into the age of CNC. Some people were quite happy using 2D. It accomplishes a LOT when you compare it to the old way of multiple set ups and hand blending.

One of the food companies found out inthe 50s that too complete of a package was shunned. They found that if they included egg powder in their pancake mixes, housewives didn't buy it. By including the housewife with a silly duty like cracking an egg into the mix, the pancake mixes took off.

I think two axis mills are from this same type of thinking, or the need for full three axis just isn't there in the eye of the purchaser. Memory was also expensive and if you could save memory by doing the Z, you could write larger 2D programs. I'd go with a full three axes mill. With large memories, and the ability to 3D profile, a full three axis just makes the most sense.

Your cousin may think all he needs is a two axis because until this time, all he has done are two axis moves with his manual mill and is thinking in mount plates and other two axis stuff. After he learns more he will want the third axis, so he might as well jump with both feet from the get go.

[slowbob]

Thanks to both of you for your replies.

You have answered the 2 or 3 axis question.

CNC Zone is great!

Thanks again!
Bob

[NC Cams]

The classic Bridgeport mill is pretty easy to make 3 axis CNC capable. A current running thread "Vinces CNC Retrofit" is a good page by page conversion tutorial. You can literally buy a number of 2D bolt on servo or stepper setups. For the Z, the neatest most direct way is the use of the Elrod Machine setup - bolts to the face and the servo literally bolts up. For that matter, you can buy a 3D Extrak and have most of the drive stuff already engineered for you.

All it takes is money and to decide if you want to plug and play or wade thru a science project..

Bridgeport used a sloppy, sort of kluged up cantilever setup that bolted to the side of the head on the initial 3 axis ExTrak. Supposedly, customers complained so much about the 3D sloppiness that they retrofitted them to something else. The nice part about the cantilever deal was that it retained all of the normal manual head drive features - bad side was that it put in a lot of hysterisis that the 3D had problems dealing with.

IN transportation terms, 2D is to a buggy whip/horse as 3D is to nitrous oxide/IC engine.The more you spend on software and mechanisms to get hysterisis free stuff, the better you'll be able to do TRUE mold quality work. Simultaneous moves do pose a challenge. Sort of like rubbing tummy and head and hopping/skipping at the same time. Takes a dedicated mind to do all that at once - 3D cnc is no exception.