Need Advice on First Bridgeport

[Tmate]

I have been using a 6" x 26" Enco bench knee mill for the past 35 years. I've decided to follow the advice of many on the forum and move up to a Bridgeport. There's a spot in my garage with 220 volt single phase power where it will fit, and I would probably use a VFD.

I have been holding off on my decision because of the bulk and weight of most of these machines. A local dealer now has a 9" x 32" Bridgeport with a 1/2 hp 3 phase motor. My import has a 1 hp motor, so this seems somewhat inadequate. Yet if it is inadequate, why would Bridgeport have used it? It also has a #7 Brown & Sharpe taper on the spindle.

I have been told that the M head machines, like this one, are less desirable than the later J heads. Also that the #7 B&S spindle tooling is hard to find. However, the mill only weighs 1,250 lbs, which is a big plus for me, as I could move it with an engine hoist and dolly if necessary.

I would welcome any advice, particularly on the hp and spindle taper. Thanks!

 

[Reddinr]

I believe it was davidpbest that made a good write-up on plusses/minuses of bench top vs. knee mills. The article discusses the types of heads as I recall. Also, search on "bench top vs knee mill" and the like. There are many threads on the subject. I'm still using a bench top mill (RF-45 type) and it still works for me but I'm looking for an excuse for a knee mill too and am researching too.

 

[markba633csi]

I believe the M head lacks the backgear found on the J heads? I like the short table machines however, if it's in good shape I'd buy it.
Larger work envelope than your Enco but other than that what is the advantage to you?
-Mark

 

[Dabbler]

For a hobby mill the M and the J heads will both work, but the M heads are a little more bothersome to align perfectly.

Your real concern is for the B&S taper. Unless you are getting a mill with a full set of collets, this should be a show stopper. THe B&S taper collets seem to be very hard to find, and the ones that are findable are from offshore, so perhaps suspect.

Without a full set of collets readily available, I'd pass on this mill - unless you know of an available BP mill head with an R8 or Cat40 taper.

 

[Tmate]

Larger work envelope than your Enco but other than that what is the advantage to you?

Advantages as I see it are spindle to table clearance and rigidity. I started to make a riser for the Enco, but I'm exploring other options first. Of course cost is always important, but not a major factor in my decision.

 

[dirty tools]

A few years ago I won a bid on a military Econo mill. my Shop has 220volt single Phase power I used a VDF. it does a great job
my shop is 10’ X 20’ a tight fit

 

[DavidR8]

My only comment is to heed @Dabbler advice.
My mill has an MT3 taper which makes tooling a bit of a trick.
Mostly I look for straight shanks that I can use in a MT3 collet. For example an face mill with an MT3 taper is near impossible to find but I did find a straight shank face mill holder.

Food for thought.

 

[projectnut]

It's a personal decision, but I would take a pass an an M head Bridgeport. As mentioned they are not nearly as powerful as the J heads, and most likely have A B&S #7 collet system. These collets are limited to1/2" tooling. In addition the M head is much harder to tram, and much easier to knock out of tram. The 32" table is the smallest available.

They are lighter in that they weigh in the neighborhood of 1,200 lbs. as opposed to 2,000 lbs. for a J model, and have a shorter quill stroke of 3 1/2" as opposed to 5" for the J head.

Here's a link to a Bridgeport brochure so you can compare the various models:

Bridgeport Machines Inc. - Publication Reprints - Series I Turret Millers, Attachments, Accessories - 1971 Catalog | VintageMachinery.org

 

[mmcmdl]

Tmate , plenty of BPs in the Baltimore area . I would pass on this being an M head and not an R8 spindle .

 

[itsme_Bernie]

The M-head Bridgeport will definitely be a step up in rigidity, and most likely a step up in work envelope. I’m not be sure if the machine is enough of a step up for you to bother moving it in and paying for it if you are keeping both machines.
If you didn’t already have a knee mill, but had something small, I would say it would be a huge step up no matter what.
The J-head Machines are heavier, and besides almost doubling the quill travel, there is power down feed!
It was a big plus for me moving from a milling head that did not have power down feed to having the power downfeed and backgeared lower spindle speeds.
R8 tooling is much more available everywhere, BS-7 is not as much.
The picture you posted is beautiful, it’s a beautiful sample. I would not turn you away from it. Just make sure it’s a big enough step up from what you already have.

Bernie