RabidRepublican
07-19-2006, 08:21 PM
I have lathe experience but little milling experience but I have a knack for the trade so I am buying a lathe and mill for home use. After deciding on a pair of Taiwan made Birmingham machines, I've come to realize that the Bridgeport is the original and all others seem to be copies. The market is flooded with used Bridgeports spanning half a century and I need someone to steer me in the right direction. This is a link to the machine that got me thinking:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ih=003&item=130007948343&rd=1&sspagename=STRK%3AMEWA%3AIT&rd=1
Everyone probably knows that ebay is saturated with Bridgeports. I know that no one can speculate about the condition of a piece of equipment on ebay but I'm sure that someone can educate me on the preferred Bridgeport components. For instance, what is a J-head, is it a quality component, or is it something I should throw rocks at?
The bottom line is I would rather have used quality than new junk.
HEP ME PLEEEZE
Qbranch
07-19-2006, 08:47 PM
Ok first of all a J head is just the style of the head, you can make the J out in the spindle package from the side.... its a good thing.. not something you should throw rocks at ;)
About the one you are looking at:
I wouldn't buy a used mill, especially from eBay, unless i could take my runout guage there and check the spindle. This machine looks very good, and probably is, but it takes just one big screw up to deform the bearing race in the spindle, making it essentially worthless if you need any kind of precision.
Also, I prefer a Variable Speed Belt Transmission with high and low ranges, unlike this gears-only machine, which locks you in to 8 spindle speeds.
It appears that the knee handwheel has been taken off this mill, but that can be replaced for just a few tens of dollars.
There is no DRO on this mill, but that can be installed by you if you so desire, and costs a few hundred dollars for the complete kit. I really find a DRO to be an essential tool for quickly making high precision parts and not having to keep track of how many spins you have on your handwheel.
There was a power feed on the X axis which was removed. X axis power feeds are very handy for making a nice surface finish on a milled part (especially when rounding, chamfering, or peripheral milling). These also cost around 200-300 dollars depending on who makes it and what axis its for.
So Long as you don't mill much hot rolled steel or Inconel, the 1HP spindle motor should be fine for you.
It looks like this mill also has a Bijur-type spraymist coolant system. I really don't suggest you use it, as spraymist can cause lung problems. The semi-auto pump oiler looks good and seems to not leak.
Ok..... that should get you started. Private Message me if you have more questions, i probably will forget to check this thread.
-Alex
NC Cams
07-19-2006, 10:12 PM
A turn key Bridgeport CNC mill was sold by the firm as their EzTrak. A decent one (one with a PC based control aka DX32) would easily handle your milling needs. Besides, it will also give you a factory built CNC that will run G code in concert with lots of canned functions that come in real handy - built in DRO too.
Bit more pricey but a nice investment. Some guys swear at them (especially the old timers who are NOT computer literate). I swear by mine. Anyone with computer literacy, especially when they see G code operation capability and the PC based control, will drool at the opportunites it offers.
I lucked into mine, paid too much for it and it will be one of the last things I ever let go of....
The rest of the machine is CLASSIC Bridgeport iron, only spit shined with a 2 or 2.5 axis PC based, servo driven CNC.