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Bridgeport Mill


Jim S

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I just bid on a Bridgeport Mill and my wife says that 15 seconds before the auction ends someone will outbid you. Perhaps but if they don't and I really own this thing, does anyone have some data on serial numbers and date of manufacture? Again, if, I'm looking at a variant of the collet size, not R8 but ER 32. Can anyone enlighten me as to the availability and purpose for this size collet which I am not familiar with?
Thanks,
Jim

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The date is usually part of the serial number, or stamped on the data plate.

Can you go look at the mill, or is it too far away? I ask this because some things are best determined with the mill in front of you. These type of mills get a lot of use in the middle, which wears the thread in a small area. When you run the table from end to end it will be loose in the middle, and tight at each end. With the table centered grab each end of the table, and push/pull back and forth alternately to see if the table wiggles. Sometimes a gib adjustment will fix that, sometimes not. How noisy is the head? How sloppy is the spindle? Variable speed, or step pulley? Does the vari speed work smooth?

Where are you located? Lots of these types of mills on the west coast. The mill weighs around 2,500# for a late model with a 9"x42" table, and varispeed head.Shipping can add up. You might also want to check with some used machinery dealers. I have seen nice mills with digital readouts for $2,500. I got mine at an auction for $1,800, and a used machinery dealer I know has picked them up for as little as $500 with all of the shops closing. Don't be shy about some of the Taiwanese imports. I use the Acra, more than the Bridgeport where I work.

BTW, some of the sniping software can outbid you with a couple of seconds left B)

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The date is usually part of the serial number, or stamped on the data plate.

Can you go look at the mill, or is it too far away? I ask this because some things are best determined with the mill in front of you. These type of mills get a lot of use in the middle, which wears the thread in a small area. When you run the table from end to end it will be loose in the middle, and tight at each end. With the table centered grab each end of the table, and push/pull back and forth alternately to see if the table wiggles. Sometimes a gib adjustment will fix that, sometimes not. How noisy is the head? How sloppy is the spindle? Variable speed, or step pulley? Does the vari speed work smooth?

Where are you located? Lots of these types of mills on the west coast. The mill weighs around 2,500# for a late model with a 9"x42" table, and varispeed head.Shipping can add up. You might also want to check with some used machinery dealers. I have seen nice mills with digital readouts for $2,500. I got mine at an auction for $1,800, and a used machinery dealer I know has picked them up for as little as $500 with all of the shops closing. Don't be shy about some of the Taiwanese imports. I use the Acra, more than the Bridgeport where I work.

BTW, some of the sniping software can outbid you with a couple of seconds left B)
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Gentlemen:
Well I just hit the wrong button and reprinted BigGunDoctor's reply. What I meant to do is to thank you both for the response and note that indeed I now own the mill if PayPal will ever communicate with my bank. Thus I have not touched the machine and may well have bought a pig in a poke, but for the amount I paid for it, I have less in it then my Harbor Freight mill-drill. The Bridgeport can't be worse than it. Well maybe it can.

The serial number is J225660. Does this mean it was made in 1960, 1066, or 1956? I understand that these machines can all be rebuilt assuming parts are broken or too worn for gib tightening to correct slop? I also wonder if manuals can be had for these machines and if so where one might look. I am wondering if the ER32 tool holder is just stuck in place as the seller notes that an R8 collet will not fit it and I thought all Bridgeports used an R8 system. I'm certain some manufacturers could order machines for whatever their needs might be and thus assumed ER32 meant whoever the original purchaser might have been had tooling of this size. A tool holder does make sense, but I can't seem to visualize why it was used unless there was not an R8 collet that could fit the particular tool or it is an emergency collet or what. Obviously I have much to learn about machining on a Bridgeport.

Thanks again for your replies and if you have additional insights, I'd like to hear from you.
Jim

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I have a step pulley made in 1962 and it is a great machine. The ways still have frosting from the scraping because the mill was in the maintenance shop of a production stamping shop so they only used it for repair. All the parts are available and they are relatively easy to repair. You can't take huge cuts with them but they are precise and plenty sturdy enough for the average HSM. I would like a DRO but get by with no problems using the original dials (which do actually register .001 per minute of revolution). Check your half-nuts and gibs for wear (both can be adjusted to a certain degree) and the spindle bearings for vertical slop.

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Thank you gentlemen. I hope you are right. I suspect I may become a pia fixture here as I try to make this thing go. Nakedanvil: I'm somewhat confused by your collet holder picture. Are you saying that the female part of the quill takes a collet of size ER32 or do you still maintain it's an R8? The current owner believes the machine came from Caterpillar and was designed for special collets. He seems to think they are available through ebay, and I have asked him if he has any way of ascertaining the correct collet size for the machine. Ebay is selling a set of ER32 collets so I'm not sure what this means.
Jim

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Nakedanvil:
OK so we're hopeful that the spindle taper on my J Head is R8 so that the collets I already own and are so readily available from Enco and the like can be used to hold what few end mills I own. The ER32 collet holder pictured in your email fits into an R8 spindle but why would one use it? I have ten R8 collets that handle quite a few different diameter end mills. What does your ER32 holder possess in tool holding capabilities that ten different center hole diameter R8 collets don't have? Sorry for so many questions, but I just don't get it.
Jim

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Nakedanvil:
Now I understand. I hope you are correct and that the spindle taper on my mill is R8. If not, you say "anything is possible", I may have some problem locating collets to fit. I thought last night that I could perhaps have the spindle taper reground or replaced. Those solutions sound expensive. At any rate, depending on the weather in the midwest, I may find out this weekend or early next week what I now own.
Again, thank you for your help.
Jim

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I bought a full set of collets and a holder for a Benchmaster mill I bought a while back and the whole thing with spanners and a wood box cost less than $200 for new equipment.The collets run from 1/8 to 1" by 32nds.The holder adapted the #2 Morse taper to the ER collets.They do seem to hold better than R8 collets and the head is no bigger than a medium sized boring head(3" tallX2-1/2" OD).
Unless you are planning to machine really tall work and need the extra 3" the head takes up then it`s no big deal.If it`s not something you want to spend the $200 on then knock the holder out and go with your R8 collets.
If you do decide to spend the money for the ER collets you might want to consider going with a morse taper holder(you alread have an R8 holder) with the set as I`ve found it handy to use my holder in my lathe for smaller precision work.

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We use quite a few ER, EX style of collets at work. The ones that we use have quite a bit larger gripping range(.040"+) than say an R8 does. With an R8, the farther that you squeeze it beyond the rated size, the greater the wall angles get,and less gripping power. With the double taper style of collets, the sides stay parallel as it is squeezed down providing more, and straighter gripping.

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Thanks guys for all of your supportive comments. It looks like Tuesday I'll take my F350 on a trip to pick up the Mill. The current owner said he would remove the head to make it less top heavy and put both the head and body on separate pallets. I thought I would bring ratcheting straps to secure it to the bed of my truck but then thought that maybe chains with ratcheting devices might be safer. I guess at first I was going to load it and drive home but maybe it would be dangerous even with the head off that way. Anyway, I'm going to have to find several ratcheting thing-a-ma-jigs to hook the chains to. Any thoughts to someone who has no experience with hauling heavy studd?
Jim

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Get a trailer, if you don't have one. Easier to unload from, lower center of gavity, and stronger places to strap it down to.

Loading a Bridgeport is usually done by putting the forks under the upper ram, be sure to use some wood between the ram, and forks to keep it from sliding.

Wrap a couple of chains, or straps, once around low on the base pulling in opposite directions, and one over the top that wraps around the ram once in front of the main frame.

Never put metal to metal, it will slide. Always slip a piece of wood between to keep it in place. It can be 2x4's, or even some thin plywood.

Wrapping the hold down around the item will keep the item from slipping under the hold down device.

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  • 1 month later...

I just bid on a Bridgeport Mill and my wife says that 15 seconds before the auction ends someone will outbid you. Perhaps but if they don't and I really own this thing, does anyone have some data on serial numbers and date of manufacture? Again, if, I'm looking at a variant of the collet size, not R8 but ER 32. Can anyone enlighten me as to the availability and purpose for this size collet which I am not familiar with?
Thanks,
Jim

Jim,
Congratulations on your new toy. You're going to love it. The Hardinge website has a list of the SN's made in each year. As far as I know, the Series I machines were consectutively numbered which makes the exact month and day total guesswork. Since Hardinge has taken over Bridgeport, their website will have a lot of info that you will find useful. I bought one last fall and have spent the winter restoring it.
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Thanks. I brought the mill home in the back of my truck without difficulty and unloaded it with the help of my neightbor's enloader. Currently I am rebuilding the head and it looks like I will need some parts. Essentially the fine wheel is missing and the reversing "switch" is broken. The spindle taper is NT 30 and I have begun purchasing collets. Have not found a "deal" on a whole set although Grizzly sells an NT 30 adaptor to R8 which would allow me to use my current collection of collets. I assume the draw bar on the adaptor goes through it and tightens on the threads of the R8 collets.

Aside from the table that has bee sorely abused and some broken parts, the machine looks intact. I will keep you informed as I progress in rebuilding the beast.
Jim


Jim,
Congratulations on your new toy. You're going to love it. The Hardinge website has a list of the SN's made in each year. As far as I know, the Series I machines were consectutively numbered which makes the exact month and day total guesswork. Since Hardinge has taken over Bridgeport, their website will have a lot of info that you will find useful. I bought one last fall and have spent the winter restoring it.
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NT30 is a big improvement over R-8. Much better support due to the longer taper and quicker tool change.

That makes sense. I suspect I will get the R-8 adaptor and some NT 30 collets. Right now I need to remove quill assembly as I suspect the bearings are toast. Maybe not, but something is locking up the spindle from turning. I suspect this thing has been outside or at least taken some water as there is an internal light coating of rust and water in the oil. On top of that there's enough xxxx and garbage to build an ark.

I can't seem to locate a setscrew in the quill to loosen and my efforts to remove the quill cap with a homemade spanner haven't accomplished anything. If anyone can enlighten me as to what I'm doing wrong in trying to remove the quill, I'd appreciate it. From what I've gotten off the net, one removes a set screw from the quill and unthreads the quill cap then the quill assembly can be driven out by tapping on the splined end of the shaft. Otherwise, I need to replace some parts in the safety clutch (plunger, spring and shims). Thanks.
Jim
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First thing to check is that it is in high, or low gear. There is a lever on the side, and a lever on the top that shift the gears. I routinely lock up the spindle by just shifting the side lever to do this, kind of like having the trans in forward, and reverse at the same time. I do this for some indicating , as well as some of the rework jobs I do where I need to keep the spindle aligned.

Also before you go ripping into the spindle I would suggest getting a manual. It is easy to get things all fouled up if done incorrectly. I believe that they use annular contact bearing in the spindle, probably class 7 for accuracy.

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Big Gun Doctor:
I fear that your recommendations will not work but I will recheck it this weekend. The notion of being able to lock up the spindle would prompt me to avoid further dismantlement of the head assembly if I could be certain that the bearings were not toast. I have a complete manual as well as a step-by-step procedure for taking apart the head which was done by a contributor to the web. What has concerned me is the "bearing preload" which I have little if any information about. So, your recommendation is well put. If I can get the spindle to turn without further disassemby, I will do so and see what happens when the machine is put under power. I do have some missing parts in the head as noted last night and I also have at least one missing part in the table mechanism which will have to be addressed before tackling the three phase motor issue. I'm not anticipating a proble mthere although I will have to procure another motor and wire things accordingly assuming my motor works.

Anyway my manual states that a set screw is removed from the quill an a pin wrench which I have made is used to unscrew the bottom of the quill. Nothing budges and I can't seem to locate a set screw. If I can free the spindle, I will clean what I have taken apart, repaint and reassembele moving on to the table and then the motor issue.

Thanks for your suggestions.
Jim

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Pay attention to what Bigun' said. I think you got your mind set on one thing and it's blinding you to other possibilities. Been there, done that. The bearings are the LAST thing you should be suspecting. They should be pretty weather tight and sometimes get noisy but rarely lock up. Gearbox, spindle lock, check everything.

If you have not found the setscrew, you should not be trying to unscrew the cover.

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