I am and have been looking for a Bridgeport type knee mill, but I am so undecided on what to get.

The requirements are simple -

Simultaneous 3 axis contouring.
Programmable spindle speed.
Single phase would be nice (maybe by simply changing the VFD?)
At least a 30 taper.


My questions are just as simple -

What kind of controls are the most readily avaialble and have current support? (I REALLY like the centriod stuff and have been semi-looking for a machine with a retrofit in mind)

Some bonus features would be good conversational interfacing.

I see a lot of the "older" controls have RS232 interfacing, but what is required of the OS on the pc to interface with these older machines?

This machine will be going in a garage at a house, so it needs to be "bridgeport" sized - I think the ceiling is about 8' tall.

You are essentially describing a V2XT. IT is a full CNC, non-mechanical variant of the classic vertical mill.

If you find one with the DX-32/BMDC based, mid 90's controller (stay clear of the earlier FMDC unit) you can plug in a 4th axis (if you can find one used) and rock on.

Although V2XT does NOT have manual handles, I've seen DIY kits or plans for kits that guys used to craft up manual handles. The Eztrak and/or manual machine handles and stuff should interchange with a bit of adaptation.

There are some 3D ExTraks out there but they don't all have the "good" 3D adaptation. Some are actually 2.5D so BE CAREFUL.

Price wise, the V2XT's run anywhere from $10K to $16K, depending on condition.

THe iron is pretty much stuff you can service yourself. The BMDC is still fairly adequate PC DOS based control. However, only EMI does any "factory" servicing. THey are NOT necessarily inexpensive. Phone support is hot and cold, if you can get it and depends on who you can get to talk to.

There are other BPT's that use the same controller (Explorer, VMC, etc). Some folks swear buy them, some swear at them, especially in 3D mode.

As an asside, consider Haas and consider it strongly.

The Haas TM's come in a lot of variants. Big, small, ATC, no ATC. The TM is what the V2XT would/should have evolved into had BMI not gone belly up. It has the same contoller as their BIG VMC's and 4th axis are readily available - the 4th axis for BPT's are like hen's teeth. True 3D and 4D work is a snap if you buy the right options. Send a PM to GAR and ask for his advice as his son has 4 or 5 Haas's and they rock on effortlessly.

Cost wise, the mid 90's Extraks ran in the mid $20'.s Today, around half that and only used. V2XT's are bit more but they have both more and less features compared to EzTak.

Today, a semi-loaded Haas TM was last priced at $29K new, loaded they are in the $30's - haven't checked the used/refurb market but I suspect they are out there.

If I had it to do all over, especially after what I went thru to get my Trak to do what a Haas does out of the box, and the not readily available nature of 4th axis and other service items, especially for the PC/BMDC control, I'd think long and hard about EVER jumping on the legacy BPT CNC bandwagon again.

IT was the only decision I could make at the time. I wish I'd gone in a different direction. Today, I'd strongly advise about buying the best machine I could barely afford and, today, that would probably be the Haas.

Thanks for the more than informative reply, that helped alot and was exactly what I was looking for. I missed out on a deal not to long ago, a V2XT that was almost brand new with only 199 hours on it - it went for 4500$. :(

As far as the BPT's are concerned you like the Eztracks and V2XT's more than the others? I've noticed a ton of Boss BPT's - what are the drawbacks of those? (It seems the air actuated stuff gets in the way of an otherwise easy retrofit?)

I'll check out the Haas TM's as well.. Thanks again for the input!

The Extraks are effectively a CNC retrofit of a classic Bridgeport mill only done at/by the factory - and done quite well all things considered. 3D can be clunky (actually 2.5D) so be real careful when you consider them.

'Traks are NOT a true VMC whereas the V2XT is considered by BPT as a "mini VMC". It has/uses the same programming manual as the VMC's and uses some of the same auxilliary cards as the VMC.

The only detraction of the V2XT is that it is NOT a manual machine - no handles to operate on X, Y or Z. You could adabpt handles to X and Y but not Z. Otherwise, it takes up essentially the same footprint as a BPT mill.

Boss's are not something I'm personally familiar with. I'm pretty sure that they were factory fitted with steppers and they tend to be a bit bigger, heftier - the BMDC stuff is all later model true commercial servo based. The older you get with BPT's the more you'll have to rely on aftermarket and/or used parts to service the machines. Some of the older BPT's are still stepper techology.

Hardinge has epparenlty elected to NOT support the old Bridgeport iron when they took over the parts and service of the Bridgeport name after the bankruptcy.

I'm pretty sure they even off-loaded the servicing of the BMDC's to EMI. If you're expecting legacy service from the "factory" of anything made prior to mid/late 90's that says "bridgeport" on it, you could be disappointed.

This is not to say that you WILL be, just finding service by "calling the factory" won't necessarily get you going as fast as you might hope. YOu might have to shop around - there are guys out there sill servicing the legacy stuff but you'll have to look.

If you do consider a retrofit, you'll ultimately get what you pay for. Buy and go for a "science project", and you might be satisfied assuming you have the time and skill to sort out all the kinks. If you HAVE to make parts, you might be better off buying a ready to run machine or a high end kit.

Example: a turn key Centroid retrofit might run you $8K to $12K, plus the iron. Yet essentially ready to run V2XT's and/or Extraks run from $4.5K (you missed that deal) to $15K. Is it worth the grief to do the retrofit? Depends on your needs and intent.

Had i to do it over, instead of buying the V2XT, I'd take a different tact.

Instead of ending up with an Extrak, a V2XT (still needs 4th axis) and an Excello mill, I'd have sold the Excello (pristine) and spent the extra and bought the Haas TM (properly optioned). I could then buy a 4th axis off the shelf and have factory service but a phone call away. Perhaps pricey but much, much more timely and faster way to fly.

You have to weigh things out based on YOUR needs and budget. In my case, I'm running a business. Time is critical and I've used up my budget for science projects and equipment recycling/resurrecting. Now, I need/want simply to walk up to a machine, turn it on and have it run.

Now i still have to wonder "will it start?" and/or "how long will it run?" or "h9w much is the damn thing going to cost me to fix THIS time?". This can be a PITA and take the fun out of any business or project.

Shop wisely