Bridgeport Mill

[albertorc19]

Really liked the cartoon, the moral is: "No machine is too big, no matter how small the model"

 

[Sshire]

Cook tool and machine in Sicklerville NJ. Family business.

I'm pretty much decided on limiting my selection to step pulley machines. I've read the same thing as Lagun said about Vari-speeds and VFDs.

 

[Wizard69]

The issue of capacity applies to a Bridgeport too, any mill really. It isn't uncommon to see a space under the turret on Bridgeport mills to give you a bit more clearance. That knee doesn't have infinite movement.

I had to comment on this because the argument that you can run into capacity problems can and does come up for any tool. Sometimes you just need to be creative.

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.

 

[Swifty]

Coming back to the original questions, I personally don't think that a Bridgeport is over kill for making models. I have a Bridgeport clone, a King Rich, just a little bit bigger than a Bridgeport. I have worked with Bridgeports for over 35 years doing all sizes of jobs. It's nice to have a good space under the spindle, and plenty of room to mount a 6" vice with space either side for tools etc. have occasionally had a vice and an 8" rotary set up at the same time.

As far as what to look out for, without having to do a complete rebuild, backlash in the axis nuts can be adjusted, (so long as the nuts are not worn completely) slop in the ways can be nipped up with the gibs (you will always find that the table slides are worn more in the middle than the ends). A variable speed head is great, but don't rule out a belt drive as there are plenty of speed choices. Broken clock springs on the quill handle are easy to replace, on older models the cutout on the auto quill feed may be sticking, just needs some oiling and adjustment on the cutout screw.

Offloaded one Bridgeport from a toolroom after 40 years of daily use and abuse, with a bit of tweaking it would have been great for a hobby machine, I'm sure that you will find one that is suitable for your use.

Paul.

 

[Wizard69]

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?

No it isn't too big! This is actually the easy question to answer.

2. What are the things to check while looking (i.e. how would one know if it's worth buying?)

This is the much much harder question to answer. However close visual inspection is a must. Obvious things like gouged or scored ways should set off alarms but you need to be able to judge this against normal wear. Frankly any mill that has been used a lot will have some signs of wear. If you haven't inspected a machine before purchase it might be helpful to enlist the aid of a local machinist or machine tool repairer to look it over.

No, I'm not interested in rebuilding the top end, spindle, bottom end or any end. I'm not going to scrape the ways.

It is almost impossible to buy used anything that doesn't require at least a little work.

A working mill, that will perform accurately is the criteria. If it were your money, what would you look for.
Thanks

If you want a guarantee buy a new mill! If not that then you need to inspect the machine very very closely to make sure it will meet your needs. Even so you should expect that a used mill will require some tinkering from time to time. As for what to look for, that is harder to describe, obvious wear on the Gibbs and ways should be easy to see. Many things should be measured, such as spindle runout, but that really requires test arbors to be done well. Look for missing parts and obvious damage. Listen too to bearings with the spindle running.

 

[moya034]

Just remembered an overlooked benefit to the large milling machines... even if you only use a fraction of the table length, the bigger the mill, the more cross feed travel you have.

 

[MachineTom]

I doubt that a DRO off a BF 20 will fit the travels of a BP, in addition does that DRO have the functions of a Newall or Accurite, bolt circle, arc, segment , tool offsets, angles. .0002 resolution A dro already mounted to a unit might add $4-600 to the price, worth every penny. Watch those long beds, I sometimes get stuck where the x-y handle separation exceeds my arm span. Although I do work from a wheelchair, which adds a bit more to the situation.

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.

 

[GWRdriver]

Really liked the cartoon, the moral is: "No machine is too big, no matter how small the model"

Albert,
The cartoon was drawn by B. Terry Aspin (now deceased) also well known by his pen name of "Chuck" Terry was the staff illustrator and frequent contributor of cartoons, illustrations, articles, and books for Model Engineer magazine from the late 1950s on. Three of his best-known books are on casting and foundrywork for the amateur. I don't recall where I found the cartoon, it was not attributed, but I recognized Terry's style immediately and thought it worth keeping.

 

[kf2qd]

We all have our prejudices, but a Bridgeport is a nice sized machine. I have a Hardinge UM and it is a bit smaller, but it is very solid. Most of them cost a lot more than I have invested. A Bridgy would look real nice sitting next to it though...

 

[Sshire]

Again, thanks guys. Report tomorrow.
Tom
Yes, I have ALL of those DRO functions.
The Y scale is 16" long. My X scale is 30 inches. Since I'm unlikely at this time to exceed that X travel, I'm planning on mounting it centered on the table. At some later point (when funds are replenished) I'll get the correct length.
Since the DRO was about $700 new, I can't see getting that much back. If the BP has a DRO, that would be very nice but I'd rather get a newer/better machine for the same $ and uses my DRO. All of this will make more sense after my look tomorrow. (or I'll be more confused)

 

[Sshire]

Spent the morning at Cook Machine and Tool. Like Toys 'r Us for older kids.
Jim Cook was very helpful. Based on my uses and the fact that I'm going to use a VFD for 3 phase power, we came up with this:
Step pulley machine (variable sped from VFD and WAY fewer parts to break.
Machine newer than mid 1960's (more VFD friendly motor and chrome ways)
36" table (much better fit in the shop and I doubt that I've ever used more than 8" of X axis travel)

He just shipped 12 step pulley machines to South America but always has them coming in.

In his experience, the "short" table Bridgeports were generally toolroom machines and had much less use than the 42 or 48" tables in production. I looked at one of two 36" machines that he had and both still had frosting toward the middle of the ways. Both were vari-speed so they'll stay there.

He will call as soon as he has a nice 36" step pulley machine in stock. He expects a few in the next month or so. He also has rooms full of Bridgeport parts (in addition to the two Monarch 10EE lathes that I was lusting after)

While we wait, here are some pictures from this morning's road trip

 

[moya034]

Thanks for taking pics. I will certainly have to take a stroll through that place some time! What kind of price was he talking?

 

[Sshire]

Depending on age, condition, DRO or not, power feed, vari-speed, etc, about $1800 and up. Mostly up.
I'm figuring for a clean, low mileage, non-variable speed,with good ways and screws around $2500. I've seen many of the Craigslist specials and most looked like they were run 26 hours a day, rarely maintained.
At least I'm dealing with someone who I can go back to with a problem and, given his parts supply, some help.

 

[moya034]

Sounds like a good deal to me.

 

[MachineTom]

I will suggest that you avoid the BP power feeds, it is near impossible to get parts for the type in the photo, the newer models that have a Servo label are better, but still expensive. The add on types chi-com and us brands are repairable and tossable.

 

[kvom]

My BP is a '62 step pulley machine with a VFD. I keep the pulley belt on the 2nd sheave and use the VFD for speed control. Has decent torque down to 500 rpm, and below that I switch to back gear rather than move the pulley.

Personally I would suggest the 42" table if you have room in the shop. The 20" X travel has been useful to me many times.

I have the 1HP pancake motor, but the larger motor is good if it's an available option.

 

[Sshire]

Tom
That was my thought also. Less stuff to break and a new power feed from Enco or the rest of the usual suspects seems like a better idea. After having one in my current mill (X axis) I'd hate to do without. The difference in finish from hand cranking is significant.

KVOM
What have you done with the larger table? I couldn't think of anything that I'd need it for but I may be missing something. The 42" would fit but would be tight.

 

[Sshire]

Just found this via Google

"the series I mills, with a J head were manufactured with table lengths of 32, 36, 42 and 48 inches with, respectively, 20, 24, 30, and 36 inches of longitudinal travel"
I read somewhere that the power feed cuts those numbers by 4" so it appears that a 36" table, with power feed would give me X axis travel of approx 20"

If this isn't right, please correct me.

 

[kvom]

The Y axis saddle is 18" wide, so your normal travel is table length -18. The power feed will reduce that somewhat depending on the model.

An advantage of a longer table is the ability to keep a vise and a rotary table mounted at the same time. Another advantage is that you can use the DRO to measure long parts precisely, even things that are not part of models.

I used the table to machine the frames of my locomotive; these are 36" long. The reality is that I use the vise 99% of the time, so that the table length is not an issue. But it's nice to have it

 

[Sshire]

Your numbers make sense, so how does BP's spec sheet have 36" travel with a 48" ( they say 49") table?
I'd love a 42 or even a 48" table. If I move the basement foundation wall...
Space is frequently the issue in a basement. Good thing the entrance is at ground level at the back of the house with double sliding glass doors or I wouldn't have even considered the BP. I've seen the YouTube videos where 8 guys are moving one down basement stairs. Not happening here.