General > General Technical Chat
a Used Bridgeport milling machine
beanflying:
If you watch enough Blondihacks videos (you should because overall they are great) you will know her older mill and even the newer one run into rigidity issues when she tries to push to hard.
This is the same issue the two in one Lathe/Mill combination units run into (actually worse in most cases) before you get to their other practical limits.
While high speed (10-20k toy/hobby) fixed ratio spindles might be great at screaming tiny carbide bits into material they are not remotely useful for material removal in metal and even plastics and timber will suffer needing far more passes (time) to even look at getting a job done. Add to this the lighter gantry or stand they are typically attached to and you are going to find using it above watchmaking/small stuff painful.
OP we do have a Mech and Automation Engineering section too so consider moving the topic maybe using the button bottom left of the page :-//
Smokey:
Knowing the capabilities of your machines and working within those capabilities is super important. With that said, unless you are running a production shop you can probably slow down and take a few more passes and get the same job done with a less powerful less rigid machine. Don't expect a bench top anything to perform like a 3000lb machine.
LaserSteve:
Realitive to my post above I'm going to define milling attachment. Milling attachment means a work holder that fits on the cross slide. It does not mean buying a lathe that is a two in one unit with a powered auxillary spindle
used to mill. I agree, do not even think about a two in one unit.
with very few exceptions that were made for military shipboard use, two in one's are never stiff enough and the work area is tiny.
if you do buy a lathe, don't get the hobby ones with the 13 or 25.5 mm bore in the spindle. If you buy a 7x10 or 7x14 they are great fun, but you. have to view them as a kit of parts and be prepared to have to learn to scrape the ways.
I love my two 7x10s, but when I took one to my machining mentor, he took a large piece of damaged
carbide rod stock, threw it on the floor , found a piece wider then the ways on the mini-lathe. He then brazed it to a piece of iron rod, and shaped it on precision diamond tool sharpener.
That was my scraping tool.
During summer break I spent three days bluing and scraping, again and again. When I was done and took it back to him to testing, on a one inch brass bar turned with live center, it held .001 or less over eight inches. Factory ways were uneven until scraped.
That made me happy, but the 7x10 is underpowered for prolonged working with steel. Great for plastics, brass, soft iron, and aluminum. He actually was happy with the parallelism and TIR after I was done. Then he had me run the same test on his Hardige. Lesson learned.
Mini-lathes, for the most part, trippled in price over the past three years. Then you end up replacing the plastic change gears with metal aftermarket kits.
One other thing. Have a clean dry place.
At work during an official "clean the lab day" demanded
from upon high, a secretary stripped a tabletop mill of all lubrication
and protective films. So proud of cleaning LaserSteves' filthy, evil, machine. I was off work that day
When I got done, she was transfered to a more suitable position. Rust had started immediately. Some machines use slloys that need a protective film at all times.
The environment matters.
Steve
EPAIII:
First, your price range does not sound impossible. But your location makes that a difficult statement for me to back up.
Without accessories no milling machine is of any use at all. Collets, milling vise, cutters, parallels, edge finders, clamp set, drill chucks, rotary table, more clamps, etc. You never have enough clamps. The list goes on and on. I bought my mill over ten years ago and am still buying accessories. It is a never ending parade. I am sure I have spent as much on accessories as on my milling machines themselves. Perhaps more.
A "Bridgeport" is kind of the "Scotch Tape" of the milling machine world. Everybody knows the word and it is almost synonymous with "milling machine". And there are many, many Bridgeport copies or clones. So it is a word that comes to the lips quickly when milling machine is mentioned. That does not mean it is by any means the best and I have seen people curse at them for years and cheer in the streets when they finally replace it with a better machine. But they are not the worse either and many find them significantly better than Chinese or other "import" machines.
You only say it would be for making small and accurate parts. One man's small is another's giant. And accuracy comes in many, many tolerance ranges. You may want to refine those concepts with more definite numbers before spending the money and going through all the trouble of finding a machine to buy. i will say this, almost any milling machine can hold an accuracy of +/-0.001" or +/-0.025mm. I have two milling machines: one has a work envelope of about 2" x 5" x 4" or 50 x 125 x 100 mm. The other, which is a Chinese made import and isn't particularly big either, has an envelope of about 18" x 7" x 10" or 450 x 175 x 250 mm. Both had to fit in my garage which has an 8 foot ceiling. A Bridgeport or at least most Bridgeports or clones would not. Of course, you may not have that problem.
As for buying a used machine, I would never do that if I could not inspect the machine before buying it. Used machine tools can be found in almost any condition from better than new down to only fit as a boat anchor and completely un-repairable for anything less than twice their original price. I am not exaggerating. It could be quite disappointing to spend thousands of dollars, spend more and wait weeks for shipment, and then find you have a worthless machine and no recourse.
I know nothing about buying a machine in your location. I can't speak to that. Nor do I know which sellers would be willing or able to arrange transportation there. Perhaps you can find someone local to talk to about those details. And there must be some local dealers who have either new or used machines that you can look at. Perhaps not in your city or town, but somewhere within driving distance.
I would suggest that better places to ask this question would be:
https://bbs.homeshopmachinist.net/forum/general
or
https://www.practicalmachinist.com/forum/categories/general.38/
Good luck!
--- Quote from: xzswq21 on October 12, 2023, 08:02:27 pm ---Hello
I wanted to buy a Taiwan-made milling machine such as PM-728 or PM-833 for cutting small and accurate pieces but I have seen most of the people recommended to buy a used Bridgeport milling machine. is there any chance to find a decent Bridgeport milling machine under $5000? (accessories are not necessary).
Country: United Arab Emirates
(The sea freight fee should be estimated later)
Thanks
--- End quote ---
LaserSteve:
For the OP, India does a lot of manufacturing on manual machines. There are some really interesting videos on YouTube, doing manual machining on small and large scales.
My point being there may be perfectly fine simple machines from from other nations closer to you. I have no idea who the manufacturers are, as those videos almost never show closeups on the
nameplates.
Critical post on my Geography skills coming in 4,3,2,1...
:)
Steve
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