Bridgeport Mill

If one were "hypothetically" looking (thinking) about a used Bridgeport mill (Series I), two questions come to mind:
1. Is this too big for model engines?
2. What are the things to check while looking (i.e. how would one know if it's worth buying?) No, I'm not interested in rebuilding the top end, spindle, bottom end or any end. I'm not going to scrape the ways. A working mill, that will perform accurately is the criteria. If it were your money, what would you look for.
Thanks

Sshire said:

1. Is this too big for model engines?

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Stan,
This is one of those things that is "relative" . . . it Could be too big, depending upon the size of the work you have to do. A Bridgeport table is a fairly massive thing in comparison to a small part, and even under the very best conditions the table and advance mechanism can have a relatively large amount of friction, inertia, etc. So if you were milling a slot, with say a 1/16" end mill turning at a bazillion rpm, you probably wouldn't "feel" much of the cut, if any at all, and more importantly you probably wouldn't feel the moment when the cutter goes Snap! due to being accidentally over-fed. On a much smaller mill, with less moving mass and internal friction, you would be able to feel some of the cut and hopefully avoid that Snap! sound.

You can nearly always build small things on a big machine, the reverse is almost NEVER true.
...lew...

I must say I agree with Lew. I at one time had a Rusnok mill. very nice machine but to small for virtually any thing I did, and I might add its size didn't keep me from breaking two 1/16 end mills in the same cut. Depth of cut figures into that .05 was to much and probably would have been on any machine. My take would be if you have the room, can afford it, get a Bridgeport. Then it will be large enough for any conceivable project, the opposite is not true. That's my two cent's worth.
Art

Another vote for the Bridgeport. If you have room then get one. Unless you're hobby is repairing wristwatches!
If I had to lose mine and downsize to a smaller mill then I'd probably just give up and find another hobby.

I agree with Harry about the 'feel' with small cutters. I snapped a 1.5mm cutter last month.
But I also drilled some .010" holes in 1/8" dia. tubing ok.

Only thing I hate is cranking the knee up and down all the time. One day I'll make a Z axis motor for it.

Since I have had access to a full size mill at work I have not used my mini-mill in 2 years.

I would love to have a Bridgeport at home.

vascon2196 said:

Since I have had access to a full size mill at work I have not used my mini-mill in 2 years.

I would love to have a Bridgeport at home.

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I missed the Bridgeport Mills I had in Singapore Air Compressor Plant.The Okamoto Grinders.All the Ingersoll-Rand Air Power Tools.

2001 end June,Gus as retrenched and plant shut down with production moved to Nanjing,China.
Along with a full complimentary of machines tools went to the Rag n Bone Man by the kilogramme.
There were two Leblonde Precision Lathes,Vertical Slotter,Shaper,200 ton Deep Draw Press#,100 ton Air Bend Press,Bending Rolls and all the pressure vessel production equipment designed and built by Gus and his men.Well that is history made worse by bosses who believed in moving everything to China.
And the latest-------they are about to close down the China Plant.

Today I make do with Japanese Sakai mini lathe and vertical mill and a China Drill Press which I had to coax to drill properly and straight.With these machine tools,I built mini steam engines. It is true, you won't break 2mm
end mills on the Sakai Mill.

keith5700 said:

Unless you're hobby is repairing wristwatches!

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Exactly. I have nothing against Bridgeports, they are fine machines, but I do greatly disagree with the folks who always tell us we've got to have a workshop full of big industrial machines to do any model engineering worth doing. That's simply not true. I've had several opportunities to pick up Bridgeports (or good clones such as a Supermax) over the years and in each instance I took a hard look at what my now and future needs would be, and at the space I had available, and made a decision to pass them up. For me it was how often I would Have to have that much capacity and power vs. it's large footprint in a limited workshop space which needed to accommodate several other machine tools.

Since then I've paid attention to the jobs I've had to do on the mill I DID buy (7x30) and only once in 30+ years have I needed a longer table, to do a small 7.5"ga locomotive frame in one setup. I circumvented that problem by doing what any self-respecting model engineer worth his salt would do, I improvised and spent a little extra time to make the setup twice, to knick off that remaining 6", and it all came out just fine.

As I said in my first sentence, . . it's all RELATIVE to what job you expect to have to do. If you have the need, the space, and the means then by all means grab yourself a Bridgeport.

I would love to have a Bridgeport mill. Currently I have a LuxMill I acquired in 1985. This mill is still available under many OEM names such as the Grizzly G0730. I consider it just barely adequate in size. As a matter of fact I made a head spacer that increases the maximum distance between the spindle to table by 5 inches. This was the only solution that allowed full use of my 6" rotary table mounted to the Mill table and be able to use Jobber length drill bits in a Jacobs chuck mounted in the spindle. This would have never been a problem had I had a Bridgeport mill. If I had it to do over again I would have purchased a Bridgeport back in 1985.

I have a 40 year old BP and would only trade it for another with less wear. BP's are industrial machines and 99% are used as such> Mine had been set up CNC then stripped of CNC when sold, but the Ball screws were left in,and they are great. instead of 12" of Y axis I can use only 10, no loss really, X is also a little tight at the end range, so only about 22" of X. One thing about a BP with wear is you can still do tenths work as long as you learn the tricks to do it. a good DRO helps.

BPs come in two head styles, belt change or varispeed, known as 2J heads. Without a doubt the 2J is great in speed changing just crank the dial to the speed desired. They are also known to be noisy. If it rattles when you run at it, it needs the motor sheave and bushing and likely the sheave replaced, figure $300 for parts, the rattle shows up loudest at the 1000rpm area. A good BP will whir a very nice tone all the way to 4K rpm. If it doesn't rattle when you buy it, in home use it likely never will.

A BP has a 1:6 reduction gear, stick a 2" shell mill in there crank it down to 200RPM, and mill off a .5 x 1" in a single pass. The best thing about BP is they have been made forever, lots of parts new and used, many accessories, the best machine for a one mill shop.

Don't be confused about the High/Low switch on the motor, it is a one speed motor, low refers to low gear, and the motor needs to run reverse for the spindle to turn the Right direction. Also they run great off a VFD, which is how mine is setup.

Sshire,

Can't give you much advice as to what to look for due to my limited experience, but I do see this nice looking Bridgeport with recently scraped ways in your area: http://philadelphia.craigslist.org/tls/3809791160.html

There was a guy selling one in Consohocken a few weeks ago for $300 but I don't know what the condition is (poor, I’d bet) and I can't find the ad anymore. I see another one for sale for $2k but it starts off say it is "old" and has no DRO or power feed.

I'm in the midst of putting together a Republic Lagun 10x50 I bought a couple years ago (may start a thread about that). I've been looking at it recently wondering if it will be too big or unwieldy for model engine stuff... I guess I'll find out soon enough. I plan to do other stuff besides model engines however, so I know the size will come in handy for me. Worst case scenario is I buy a smaller milling machine to add to my repertoire.

I certainly don't "need" industrial machines, but holy cow, I love having them in my shop! I've come to the conclusion collecting quality used industrial equipment is one of my hobbies in and of itself!

This picture is awesome...it should be a T-shirt.

I have a Bridgeport head mounted on an old miniature horizontal mill ,I only have about 10" by 6 " usable travel but it is only the size of a bench drill press and I use it as one as well as a mill. If I need to mill something big I just go to my buddies place and use his full size one I wish I could send a picture of it but I am in Kuwait for a long stretch and the my workshop is in California.

motmaluk said:

I have a Bridgeport head mounted on an old miniature horizontal mill

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motmaluk,
Would that be a Burke #4 bench mill by any chance? I have a real nice Bridgeport M-head waiting to go on my Burke #4.

No it's not a Burke,it's an English make beginning with A maybe an Ajax? I got it 25 yrs ago along with a 356 Porsche and a shotgun for 1500 pounds. I only wanted the Porsche but the guy made me take everything! I am rather glad he did.

Harry, it's much more than just the capacity for me. It wouldn't really bother me if the table was half the size it is. I can't think of anything I've ever cut more than 12" in one go.
It's the quality, accuracy and rigidity which I wouldn't like to be without.
Everything I've done on my v8 I could have done on a miller half as big as a Bridgeport.
But it wouldn't look like it does now, wouldn't be as accurately made, and would have taken a lot longer, with more mistakes, frustration, etc.

I had the space available, and got a £10,000 quality machine for £500 plus £200 for new bearings and a bit of an overhaul.
I would concede that most hobbyists don't NEED a Bridgeport, in the same way that most people don't need a Porsche or a Brightling or a 42" plasma screen telly.
Cheers, Keith.

Thanks everyone. Keep the posts coming as everything has been VERY helpful and has given me a lot to think about. I'm going too a local machinery dealer who has 8 to look at. I've gotten the serial number list and they seem to range from late 1960's to early 1980's. Belt drive and vari-speed. Different table sizes. Some with Accurite or Newall DROs. I plan on removing the DRO from my BF20 so that is probably not an issue. I'm leaning towards a belt drive and using a VFD for 3 phase power.
I'll report on what I see (with pictures) so I can get more advice.
Then there's the issue of a rigger as everyone I know (except me) has back issues. But that's for later.

keith5700 said:

It's the quality, accuracy and rigidity which I wouldn't like to be without.

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Keith,
You won't get a word of argument on that from me, I agree completely. One of the things I have to contend with on my mill, which in most respects gets the job done, is lack of Bridgeport-level rigidity and repeatability, which I appreciate. A DRO solved the repeatability problem but when I take one of those occasional robust interrupted cuts you can tell that more metal in the castings and better fitting gibs would have helped. BTW my machine is a Taiwanese 1980s-vintage combination Horizontal/Vertical knee mill. There have been a few times I thought to myself I shoulda' bought a good vertical (I came VERY close to buying a Supermax, also Taiwan) but space was a big factor, and I wanted the combination Vert-Horiz mode. That has been extremely handy to have.

Don't rule out BP clones. There were a handful of clones built in the 80's that rival and arguably outperform a BP.

Something else to consider is tool speeds. If the majority of use will be smallish, you might want to look for something with faster spindle speed.

If you play with a speed/feed chart for a few minutes you'll quickly see optimum speed for common endmills are double what a BP spins at.

All that being said, I have an Alliant with most of a CNC conversion (no controller) wired with a VFD. I don't use it everyday, but I wouldn't trade it for the world. I know it's limitations though.......

Sshire,

I'm curious what dealer you are working with and what their prices are like. I may need to call them in the future for something.

Last time I talked to a Lagun engineer he said the vari speed mills don't like VFD's, but they are fine for the belt driven units. Mine is a vari-speed, so I'll be running it on my Arco rotary phase converter. My lathe is belt driven and I'll be using a VFD on it.