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Old 07-13-2004, 02:55 AM   #1 (permalink)
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What to look for when buying a bridgeport?

I was curious and hopped on ebay and noticed some mills are going for $5,000+ while others are around $100-$500. I know enough to operate it but im not sure of which options can be had with it and such and what to look for as far as wear and tear. Generally i would just use it for drilling and try to adapt it to notching tube and such. Thanks
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Old 07-13-2004, 03:08 AM   #2 (permalink)
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You will see price differences due to several things. Is the speed change step pulley or variable speed? Variable speed will cost you more. Digital readout and power feed(s) will cost you more. Also the brand name, obviously The Bridgeport name will cost you more than a Chinese made version. Is there any tooling included? Table size might might affect the price a bit, but probably not much on used.
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Old 07-13-2004, 03:11 AM   #3 (permalink)
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I've noticed that tooling, clamps, vises change the price dramatically.

I'd pay $5k for a setup Bridgeport with a good selection of tooling, before I'd drop $1k on a bare mill. Check out a tool catalog and see how much tooling costs So it's even more complex than what you think. I imagine when I get mine one day it will be through a machinist friend that knows what they're doing.
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Old 07-13-2004, 05:37 AM   #4 (permalink)
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Quote:
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I imagine when I get mine one day it will be through a machinist friend that knows what they're doing.
Bingo!!! I have a buddy who is an expert machininst/bargain hunter who will be going with me to get my lathe in the next couple months. We'll hit the various tool shops, and he'll advise me based on budget, space, and machine/tooling constraints... Get someone who knows what to look for in a machine and also what you'll "need". It's equally likely you could get something oversize as undersize, if this is for personal/garage use. If it's going in a big shop, then I guess it might not be as big an issue...
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Old 07-13-2004, 06:03 AM   #5 (permalink)
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Great trread TR

I would thin it would be worth your time to "hire" someone to advise you on buying one if you are new to it, assuming you don't happen to have a friend who is a machinist. I would think a nice crisp $100 bill would be fair to toss someone's way for some advice in buying second hand equipment like a mill or lathe. Probably be good to take them to lunch or dinner and pick their brain to soak up all the info you can too (you pay of course).
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Old 07-13-2004, 06:22 AM   #6 (permalink)
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Quote:
I'd pay $5k for a setup Bridgeport with a good selection of tooling, before I'd drop $1k on a bare mill. Check out a tool catalog and see how much tooling costs So it's even more complex than what you think. I imagine when I get mine one day it will be through a machinist friend that knows what they're doing.

Exactly. some things to consider


1. variable speed will bring the price up
2. power feed (avoid a bridgeport with the old gear style power feed as it tweaks and ruins the table over a short period of time)
3. Positive pressure oiling system (a small box mounted somewhere on the bridgeport which has a handle to prime the system with pressure (AVOID GREASE ZIRK FITTED BRIDGEPORTS...the soaping elements used in grease alone will cause innacuracies))
4. Bearings (a couple of drops of light spindle oil only every 8 hrs of use lube the spindle quill bearings)
5. DRO (digital read outs) AVOID sony readouts as these are absolutely junk and arent sold anymore, some snakey salesman will try to sell these or you may see a bridgeport on ebay with one...dont bother paying extra for a DRO if its a sony OR if it wasnt properly setup. It takes a extremely good machinist/millwright to setup a read out. General rule of thumb is .0005 over 18"s for dialing the readout in.
6. Way wear! You may find a bridgeport that has good looking ways and move the table to the limits only to find the majority of the wear has happened in teh middle of the ways and most of the work in the middle of the table causing longer pieces to be cut innaccurate. Most work on a bridgeport will most likely be done with a single vise in the middle of the axis's.
7. Table wear! The table on a bridgeport is a accurate surface, knicks dings and warpage from not leveling the bridgeport will cause it to be out. If the table is out you wont get a accurate part. We stone our tables and use a surface ground disk that slides all the way down the table checking of high spots. We have also seen a table warp because of the machine not being level and from a large bridgeport gear driven power feed on one side.
9. Air chucker, these are handy tool accessories that tighten your R8 collet with a push button (these are generally the spoils of a production shop)
10. Your quill/spindle This has a special spring in it that over time will snap. When this happens it takes alot of force to push that spindle in the up position (you wouldnt believe what they weigh)
11. A bridgeport is a 9 axis machine and each part must be in good condition/working order to make good parts. Mostly look for deep gouges-a high amout of wear on the mating surfaces.
12. When you get your bridgeport sweep in the head with a dial indicator and make sure you are purpedicular to the table with the spindle. Some novices also trust the hashmarks on the backside and think that because they set them at zero on teh degree markings that they are. I havent seen one bridgeport that was at zero on the hashmarks and was purpedicular to the table at the same time.
13. Spindle motors can be expensive, watch for a auction that states that it runs well and works well.
14.A pretty bridgeport doesnt mean a good or accurate one, its whats inside that counts. I have seen a extremely ugly bridgeport that was a rebuilt with hand scraped ways be much more accurate than one with a pretty paint job

Buying online tooling is a hit and miss but hopefully nobody here will get burned, Good luck!
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Old 07-13-2004, 06:26 AM   #7 (permalink)
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Quote:
Originally Posted by DRM
Great trread TR

I would thin it would be worth your time to "hire" someone to advise you on buying one if you are new to it, assuming you don't happen to have a friend who is a machinist. I would think a nice crisp $100 bill would be fair to toss someone's way for some advice in buying second hand equipment like a mill or lathe. Probably be good to take them to lunch or dinner and pick their brain to soak up all the info you can too (you pay of course).

I have done this for a few people and have found machines for people I never had a problem and didn't mind that someone would ask me for advice since I am a machinist. It is a wise choice to take someone along that knows what to look for for example on a bridgeport you need to look at.... Knee ways on the y axis table and sadle ways on the x axis, look at the quil and turn it on if possable? listen to the head, make sure low range and high range both work. Check the shives on the head for wear make sure both forward and reverse work on the head eletrical switch there is tons more to look at just bring a chinist with ya it will be worth every dollar you spend on him cause there is some real junk out there.
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Old 07-13-2004, 09:10 AM   #8 (permalink)
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sweet keep it comming
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Old 07-13-2004, 09:41 AM   #9 (permalink)
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For non-production shop work, I'm not frightened by the cost of tooling. Same holds true for the machine, if you're not making production runs of parts, you can live with some inaccuracy. Once you realize the inherent inaccuracies of your machines, you can learn to deal with them during setup, etc. Many stories out there of the old machinist who knew where the ways were worn and he'd tweak the carriage/table as it approached the rough spots. Nearly as many stories about the rusty old machine out back that was brought inside when needed and degreased and run and found to be acceptable.

A good vice might cost some $ (a Good vise as well), but if you're not making multiples of a part, nor are doing production work, you'll be amazed at what you can do with just a few cutters. A fly cutter and half a dozen HSS end mills and you'll be making chips fairly cheaply, maybe only a few hundred dollars.

Again, if you're only making one-off parts for your rig, the tooling requirements are likely to be modest at worst. I haven't spent more than $100 for lathe tooling in many years and the machine gets used so much I don't know how I got along without one. Amazing the tools you can make that you didn't know you even needed. When I worked as a machinist, I did the vast majority of my work with a 1/2" roughing cutter.

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