Retrofitting Jig Borer with CNC

I am wondering if anyone has pondered this conversion. I was thinking about using it for 3 axis milling, for prototyping models. I do not need the travel of a BP.

Bad idea? Good idea?

TIA

John

You do not mention the brand of jig borer you are looking at converting. However, from other posts, it seems many feel a jig borer is not really designed for milling.

I am open as to brand but need a machine smaller than the typical Moore 2, or BP knee mill. I realize that the jig borer is not as efficient as a real mill, but may have some precision advantages. They are way cheaper, however, which appeals greatly.

I believe in the moore book it said you could mill with their jig borer. Haven't seen that book in about 20 yrs and don't remember the title. Maybe someone does and can verify it? I think the real issue is if you were to use it for a lot of 3d work you would trash the screws, which are not ballscrews by the way.

I once owned a Moore no. 3 that had been retrofitted (by Moore) with stepper motors for NC control. It even had some contraption to automatically activate the quill feed mechanism. The special cast brackets that held the motors would have fit on a Moore no. 1 1/2 as well and would have been perfect for your project. It also had air cylinders pushed the table locks. Naturally all the NC stuff got thrown away after I converted it back to all manual use

ALL the NC stuff, even the steppers and the brackets? Oh well. I have seen some high-speed grinding heads for Moore jig bores. Do you happen to know if they will fit the 1 1/2?

John

Depends on what you mean by "high speed grinding head" as there are universal ones that fit most any milling machine or jig borer, and then there are the Moore heads made just for their jig ~grinders~...i.e. won't fit any jig ~borer~.

Pratt & Whitney, even on my 3B that weighs close to 15K, was careful to point out that only light milling was permitted if you cared about keeping the machine in shape for its designed purpose. Jig Bores are also way down on HP compared to mills, This 3B has a 1 1/2 HP motor.

John

and P & W 3B has 30 x 60 travels does it not? Not to mention you always have to drive the screws the same way for final positioning. I'd say its cheaper and easier to get get a 20 x 20 x 20 3 ax machining center from the early 90's than do what you want to do. Jig borers were meant for precision placement and alignment of holes. period. The ways as I understand it are not well suited to milling forces.

Dunno about P&W's but when I manufactured tapping machines, I didn't even own a manual milling machine (did have a Maho CNC mill however) Did all my manual milling on Moore no. 3 and 1 1/2 jig borers ! Worked fine as most of my work involved aluminum. In theory the table should jump as it sits on inverted V ways but I found in practice it never did. Took some relatively heavy cuts..similar to what one might max out a Brideport on...no problem.

In the used CNC realm, what models would get me started on my research?

Thanks

John

What's your budget, time frame requirements, and expertise (and patience) with building electronic-type stuff (i.e, are you an EE, or do you build electronics stuff out of parts as a hobby, or are you just comfortable with putting together your own PC, or none of the above)? Oh, and what's the material you want to machine, and at what productivity rates, and are you talking about 2.5-axis style work, or complex 3d ball-milling of compound curves? Also - do you need an automatic-tool-changer? The answers to these questions will determine which direction we suggest...

Nothing wrong with milling on a jig borer,light milling.
Is it worth all the time and expence doing a retro,when a cnc knee mill will almost mach a jig borer for position? i dont think so.

On the subject of milling on a jig borer.

When the early jig borers were made and in the USA where the jig borer got it's name (They are called co ordinate borerson the Continent) Milling was considered to always be heavy cutting with large cutters.

Milling was in those days done with a horizontal miller and if a vertical mill was used at all, it was a big, heavy one.

"Light milling" therefore is heavy cutting compared with the kind of milling that is done on a Bridgeport.

If you have ever done a considerably heavy boring cut on a Bridgeport, you will see that a boring operation, with it's constantly changing reaction to the cut, taxes a machine more than any reasinable milling cut will.

There are several PC based CNC conversion kits on the market, Centroid comes to mind, there are others of varying complexity and price range.

The mechanical lash up isn't bad but it might involve some creativity if the kit is applied to ome other machine besides the B'port type.

I have some experience with stepper motor drive conversions, they do all right with light machines. They are simple and cheap.

Make your attck on two fronts. Choose your conversion kit and the PC and software package. Then choose your machine. Again, if it is not a B'port type, then it is you who will have to do the systems integration.

Never under estimate the effect of spindle taper. If the jig borer is small then all the spindle tooling will be very small. Machines that weigh about the same as a B'port usually have No 1 or No.2 morse tapers. Moore's shank has a realtively smaller capacity than the R-8 shank.

I am a complete beginner to machine tools, as is most likely obvious from my questions. I am very familiar with basic woodworking machinery. I have pertty good computer skills but in no way am I an EE. Price is what I am solving for. I will be mostly doing 3-D prototype models, aluminum or resin. I can go slow, and I really don't need a toolchanger. 20 x 20 x 20 would be large enough. Ideally, I would like a smallish, simple, well-built machine with an interface which isn't too archaic. Does such a thing exist? What type of machine does this sort of work? VMC, machining center, ?

Thanks

John