CNC Help Please

[pacific_v]

Well after having some minor hiccups with my manual Taig mill and also still relying on my drill-press to remove most of the material faster given I can only plunge at 1/8" at a time with my Taig mill, I have been looking for a benchtop CNC mill to help speed up the process of things, and also cause I've been dying to make some other nice things for my other hobby (R/C Cars & Trucks). Well the above being said I'm currently eye'n a A2Z Monster Mill and I was looking at some CamBam and Mach3 software to help get me going. And since I'm now currently in the market for a decent benchtop CNC setup I've asked a friend if they could assist me in creating me a CAD file for the fire control pocket milling for my remaining unfinished 80% AR lowers.

My question at the momment is what file type/extention should I ask that I'd like the CAD file to be in? whats a good type/extention that would work out with most any & all CAM software?

[ROOS_HAPPENS]

IGES is fairly universal. I personally don't like STL files. If I remember correctly, the excellent J.P. Longfellow Remington 700 files were in STL originally, before they were changed. If you greatly enlarged the bore, you could see that it was made of tiny triangles...not the best for extremely precise measurement, in my opinion.

I'd advise to just go with IGES.

[mrwetwork]

IGES is probably the closest thing to an industry standard you'd get.

[Lostsheep]

I prefer:

.iges
.stp (step files)
.x_t (parasolid)

[kcstott]

IGES is the only way to go. but ask your machinist if he wants a 2d wire frame or 3d wire frame. or can work with solids. Makes a difference when translating the iges.

[tortort]

I believe the most popular CAD\CAM software uses the parasolid kernel.
i.e. Mastercam,Surfcam,Solid Works.
Iges is neutral and should work with most software.

[pacific_v]

Thanks a ton guys, had them done in both IGES and also in DXF. I'm still currently mill shopping and I have looked at a few Grizzly's but then read some horror stories on the quality, fit and finish, as well as backlash issues on ones that were converted over to CNC. So my eye is still on an A2Z Monster Mill setup.

[VictorFranko]

IGES is the only way to go.

That explains why Boeing Satellite Systems still sends me .stp files

[xfer42]

To convert any of those Grizzlys, you will need to install ball screws. The backlash will be dependent on the ball nuts you go with.

[pacific_v]

To convert any of those Grizzlys, you will need to install ball screws. The backlash will be dependent on the ball nuts you go with.

Sounds like a big messy job for a chinese machine, then again its something I'd know much about given I've never messed with a grizzly machine.

[kcstott]

FYI on a dove tail way machine .125 depth of cut is a lot. These machines don't have the rigidity to handel a deeper depth of cut when you're taking a full cutter width pass.

Fixture rigidity, part rigidity, and finally machine rigidity all play into how much you can take and how fast you can take it.

[kcstott]

That explains why Boeing Satellite Systems still sends me .stp files

Most everyone I work with sends iges or if they are just doing 2D stuff a dxf file. I've never really had much experience wit sto files so I can't say much about them

[VictorFranko]

Most everyone I work with sends iges or if they are just doing 2D stuff a dxf file. I've never really had much experience wit sto files so I can't say much about them

Boeing (BSS) used to send ProE files exclusively, but with so many vendors, it was tough for everyone to keep current on the latest versions, so Boeing mandated that all drawings sent to vendors would be in a universal format, and the selected .IGS, that way no matter what version of ProE you were running, you could work with the drawings.
So, I get about 2/3 of the databases in .IGS, about 1/3 in .STP and a few in Creo, which is the up to date replacement for ProE.
They can not even follow their own mandate, LOL.

Boeing has sent all their old timers packing and replaced them with young, inexperienced, know nothing college kids. The place is a mess.

[pacific_v]

Could someone please educate me a little as to why larger mills even when converting them to ball screws still have a small bit of backlash compared to how a small Taig mill doesn't have any? is there a way to make a large mill not have ANY backlash at all like a small mill?

I was looking at something like this http://www.grizzly.com/products/Dril...ch-Table/G0705

and then doing something like this https://www.youtube.com/watch?v=gyaHoJc1I9s

[kcstott]

I do not believe for a minute that your Taig machine has no back lash.

The other issue is ball screws come in various grades and the precision ground screws are what is needed to produce a machine as close to a true CNC precision as possible. Lead screws are installed under tension with double roller or taper seat bearing for thrust load, so as to prevent screw whip under high feed rates and rapid traverse.

All these elements taken into consideration will add up to eliminate back lash.
but there will be a point at which you turn the handle and nothing moves, get that to be as little as possible and the back lash you do have will be unnoticible