a Used Bridgeport milling machine - Page 1
Forum section: electronics / general

author: xzswq21
author_rank: Frequent Contributor
timestamp: October 12, 2023, 08:02:27 pm
content: HelloI 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

author: jpanhalt
author_rank: Super Contributor
timestamp: October 12, 2023, 08:20:12 pm
content: Bridgeport mills are quite heavy. My copy is 2300#, so shipping is an issue. However, assuming that is that a concern, there are several for $5000 or less o eBay:https://www.ebay.com/sch/i.html?_from=R40&_nkw=bridgeport+milling+machine&_sacat=0&Brand=Bridgeport&rt=nc&Spindle%2520Horsepower=2%2520hp%7C1%2520hp&_dcat=258084Be wary of getting one that is old but looks new. It might have had a very poor rebuild.EDIT: Machinery Trader and similar sites may operate within your country. eBay is usually my last option. It wasn't that way 10 years ago.

author: Someone
author_rank: Super Contributor
timestamp: October 12, 2023, 08:44:24 pm
content: Wants to buy large and heavy machinery, asking strangers for help in profiting, in unspecified location, for n number of non-specific currency units......

author: thm_w
author_rank: Super Contributor
timestamp: October 13, 2023, 12:39:26 am
content: If you want to cut small and accurate pieces, than a Bridgeport is not really ideal.Why not specify exactly what sizes and materials you are dealing with? CNC or manual control?

author: beanflying
author_rank: Super Contributor
timestamp: October 13, 2023, 12:56:36 am
content: Quote from: xzswq21 on October 12, 2023, 08:02:27 pmGo take a good look at Stefan's YouTube channel and in particularly his slightly older content using his Optimum MB4.https://www.youtube.com/@StefanGotteswinter/search?query=optimumhttps://gtwr.de/div/webold/shop/pro_optimum_mb4/index.htmlhttps://www.stuermer-machines.com/brands/optimum/category/product/optimum-milling-machines-conventional/optimill-mb-4-3338451/Used bridgeports/clones are a crapshoot unless you or someone who really knows what they are doing has inspected it properly. The main benefits would be a little more table size and any 'accuracy' vs new questionable to none.

author: Smokey
author_rank: Super Contributor
timestamp: October 13, 2023, 01:33:08 am
content: Unless you know how to evaluate the condition of a used machine (with actual measurements for wear, backlash, damage, etc) I would say don't go down that path. Machines like mills can have a hard life and if you don't know what to look for you might end up with a boat anchor that is essentially unrepairable and will never hold right tolerances without major work (which if you don't know how to spot up front you are also probably not ready to take on the repairs).Get the Taiwanese machine. PM is a good bet.

author: jonpaul
author_rank: Super Contributor
timestamp: October 13, 2023, 07:21:45 am
content: Besides Taiwan, South Korea is a posible supplier of machine tools.Buy A new one and get a warranty.Jon

author: xzswq21
author_rank: Frequent Contributor
timestamp: October 13, 2023, 07:29:53 am
content: Quote from: thm_w on October 13, 2023, 12:39:26 amThe dimensions of pieces are usually 1" and the material is usually Aluminum/Teflon but sometimes I need to work on the steel sheets withing 4" long. Actually I want to build sensors and a base for them. If you want to understand me more you can take a look inside the Measurement devices. In these days a manual mill is ideal for me.

author: Dan123456
author_rank: Regular Contributor
timestamp: October 13, 2023, 07:47:42 am
content: What kinda tolerances are you talking about when you say “accurate”?I just know what I consider “accurate” with my little hobby machines in my shed is definitely not close to “accurate” by industry standards so figured I’d check and that hopefully helps people steer you in the right direction

author: xzswq21
author_rank: Frequent Contributor
timestamp: October 13, 2023, 08:05:11 am
content: Quote from: Dan123456 on October 13, 2023, 07:47:42 amFor the small Teflon/Aluminum pieces the accuracy should be 0.001" (0.02mm) but for other pieces the accuracy is not tight.

author: jpanhalt
author_rank: Super Contributor
timestamp: October 13, 2023, 09:13:46 am
content: For pieces that small and with a budget, I second a new or good used smaller mill. Here is a thread I started on my shop:https://www.eevblog.com/forum/mechanical-engineering/my-new-shop/msg5106417/#msg5106417The first picture shows the mill (left tool, red) I used since 2003. It was less than $200 at Harbor Freight and many would call it junk. X and Y axis run reasonably true, but you can't trust the dials completely (leadscrew is inaccurate as are thrust bearings). Z axis is basically unusable. You can feed with it, but I adapted a dial indicator to show depth. I would not recommend it, but one can get thousandth accuracy on aluminum with a bit of effort. I made a motor mounts for models (attachment1) and a stencil printer with it. Something in the $500 to $1,000 category would probably be better. Maybe a Jet brand?Depending on the machine for accuracy is a fallacy. Your measuring tools and effort is what gives accuracy. One of the old sayings is that CNC doesn't make things more accurately. It achieves the same accuracy quicker.Bridgeports give greater capacity and more rigidity. New ones made by Hardinge, of course, are quite nice, accurate, and expensive.

author: MarkF
author_rank: Super Contributor
timestamp: October 13, 2023, 11:08:16 am
content: Also, checkout the 'Blondihacks' Youtube channel.Specifically a modification she made to her PM-728VT mill.Also.

author: LaserSteve
author_rank: Super Contributor
timestamp: October 13, 2023, 06:57:12 pm
content: The correct answer is your looking for a "Rebuilt" Bridgeport, and you need to be careful about the requirement for 3 phase power. While modern VFDs used as a phase converter are awesome, there can be issues with older motors. I have a used Bridgeport clone. Issues are, finding a location big enough with a strong enough floor. 10-20 thousandths of an inch slop in the X axis, finding parts, and the lack of a DRO, if you want to hit .001 Inch tolerances, you need a machine capable of .0001". I can get close with practice, even with the wear on the cross block, but I have to use a thick lubricant and a external dial indicator. Getting 2700 Lbs/ 1250 Kg into your home can be interesting. Also, choose your spindle wisely. R8 is a great size in the US for collets, but it might be probablematic getting "English" tooling in a metric world. Get a good vise with replaceable jaws. The quality of your Vise can make or break you.These days Semi-professional table top machines in the 2000-3000$ and up class are fine for most hobbyists. In your case a Lathe with a 4 jaw chuck and milling attachment might be far smaller and easier.Every country in the World except North Korea probably has at least a few used machines for sale at any time.Expect to pay 1/2 to 3x the value of the machine for tooling. I'd check out the Blondiehacks videos. For most projects , you can hit that .001 on a beaten, used machine with shear determination, and even better if you have the three axis DRO. The question is how much of the bed travel can you maintain .001 over, in my case, on a 40 year old machine, its about 10 cm.Also if overseas, check lead screw threads and what the manual dials are calibrated in.I'm not a fan of CNC for one off pieces. I am a fan of CNC at 4 or more identical pieces. A good belt sander is a great investment, and expect to need a good power band saw for any serious hobby work.X2 family is generally too small for real home projects if you want to machine "normally".Grab the table, pull on it very hard, if you can feel anything, don't buy the machine. Buy a good dial indicator and test the used machine before purchasing.Really, really check the spindle bearings and spindle runout over its whole travel. Dropping the spindle for bearing replacement in the home shop is my next task, and that is not going to be fun.Steve

author: Smokey
author_rank: Super Contributor
timestamp: October 13, 2023, 08:03:33 pm
content: Quote from: LaserSteve on October 13, 2023, 06:57:12 pmYes, I understand that lathes are the "mother machines", but please don't make your lathe your only mill. A completely worn out Bridgeport will be more useful than a lathe with a milling attachment.Milling on a lathe, in addition to having a tiny work envelope, is pretty terrible.

author: thm_w
author_rank: Super Contributor
timestamp: October 13, 2023, 09:59:36 pm
content: Quote from: MarkF on October 13, 2023, 11:08:16 amSomething of this size makes far more sense than a Bridgeport. But it is still a bit limited for very small parts at 4,000 rpm spindle speed. You often want more than that if using small endmills and drills (<1/8" or 3mm). Depends on the desired feature sizes.Sherline offers a 10,000 rpm spindle but the size of the machine might be too small and weak.

author: beanflying
author_rank: Super Contributor
timestamp: October 14, 2023, 12:56:49 am
content: 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

author: Smokey
author_rank: Super Contributor
timestamp: October 14, 2023, 03:41:41 am
content: 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.

author: LaserSteve
author_rank: Super Contributor
timestamp: October 14, 2023, 05:22:36 am
content: 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 spindleused 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 damagedcarbide 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" demandedfrom upon high, a secretary stripped a tabletop mill of all lubricationand protective films. So proud of cleaning LaserSteves' filthy, evil, machine. I was off work that dayWhen 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

author: EPAIII
author_rank: Super Contributor
timestamp: October 14, 2023, 07:49:01 am
content: 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/generalorhttps://www.practicalmachinist.com/forum/categories/general.38/Good luck!Quote from: xzswq21 on October 12, 2023, 08:02:27 pm

author: LaserSteve
author_rank: Super Contributor
timestamp: October 14, 2023, 10:15:49 am
content: 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 thenameplates.Critical post on my Geography skills coming in 4,3,2,1...Steve

author: jmelson
author_rank: Super Contributor
timestamp: October 15, 2023, 03:51:40 pm
content: I had an ancient round-ram manual Bridgeport mill that a friend and I bought in 1982. In 2007 I converted it to CNC, but it was quite a hack job. Last year, a friend had a Bridgeport R2E3 that needed a control retrofit that he let me have for scrap price. I did a control retrofit to LinuxCNC using AMC servo amps from eBay. The R2E3 was in WAAAY better shape than my old machine, which had quite measurable wear on the ways. But, I am a LinuxCNC developer, and make CNC retrofit equipment for this market. So, I can be considered an expert.Jon

author: thm_w
author_rank: Super Contributor
timestamp: October 16, 2023, 09:47:38 pm
content: Quote from: beanflying on October 14, 2023, 12:56:49 amYes but you are not "pushing hard" when you are working on a 1" part made of teflon or aluminum. Which is what the OP is intending on using it for.QuoteNo toy hobby spindles are not appropriate, but, 10-20krpm as a spindle top end is entirely appropriate for the small designs mentioned. Small stuff is the intended purpose.

author: beanflying
author_rank: Super Contributor
timestamp: October 17, 2023, 01:13:01 am
content: There is no right or wrong with spindle speeds and machine rigidity there just needs to be a basic idea of what the compromises are and some of the downside effects.The OP started off talking about a Bridgeport/clone then went on to explain 'a' current use. There is a vast gap between this one need and the capabilities but it is very reasonable to consider that most people with our sorts of toys and a vast arena of other interests that Steel and or larger projects might come up. Why else would you consider Freighting a monster when $1k and about 100kg of lightweight mill/drill would do?A geared spindle that can get into the area of 3-4k is still ok for smaller Carbide tools but also then gives you much heavier options including tapping all the way into tool steels because you can run it slow. While you can 'sort of' work in steel with tiny carbide at 5-20k+ driving one manually would send you nuts due to snail like pace of any real operations. While there are plenty of industrial solutions that get around some of this they are more like $50k++ and are way off scope for this topic (Go watch some Adam the Machinist videos for one of those optionshttps://www.youtube.com/@adamthemachinist/videos)

author: thm_w
author_rank: Super Contributor
timestamp: October 17, 2023, 09:53:43 pm
content: Quote from: beanflying on October 17, 2023, 01:13:01 amThey specifically said they work on sensors, small items.OP probably has no clue about other options.$1k would not really be enough here.

author: beanflying
author_rank: Super Contributor
timestamp: October 17, 2023, 11:41:44 pm
content: Even locally we have a plenty in just over and just under $1k. The BV20LV as an example is still a better buy over its little brother. Really not that rigid but it will do steel slowly. The table travel (220x160x210) on the sub $1k model is really limiting so not even close to a good idea unless you want to stay with tiny stuff only.https://www.machineryhouse.com.au/m650