Thinking of buying a Bridgeport questions...

I'm considering buying a Bridgeport rather than spend too much money on my Aciera F3.

Couple of questions for the cheaper ones for sale, around £1500-2000.

What is the height of them? They look tall!

What weight are they?

Wat are the power requirements? I have a 4KW rotary phase inverter.

What type of Bridgeport? a J head? they are the most popular.

Height around 7 foot, varies with motor type "pancake" motor being the shortest

Weight around a ton, varies with table size and or other bolt ons

Power between 1-1/2 to 2hp for a Varispeed.

"4KW rotary phase inverter" do you perhaps mean "Convertor"? if so that should be fine, you can use an Inverter but then as the BP has more than one three phase motor....

Try to get a step belt head machine they are less problematical than the Varispeed version and cheaper to repair, generally watch out for spindle noise and bearing play a set of Abec 7 bearings could cost you > £300

Then it's the usual things: wear on the ways leadscrew wear fine feed mechanism faults etc, the list goes on.

Skip across to the Bridgeport Forum on Practical Machinist lots of good info on what to look for when buying cheap BP's

Paul

Thanks for that. I may just put a bigger motor on mine and raise the head. I had assumed the Bridgeports were much more powerful.

What sort of power are the drive motors?

Edited By Chris Denton on 14/08/2014 20:38:19

The extra motors on a Bridgeport are no great problem when using inverter drive. Feed motor on anything late enough to be in the suggested price range is DC with electronic controller. Power comes from one phase of the three phase via a transformer in the big contra box on the side. No great problem to run it direct from a single phase supply. Coolant pump motor is a small three phase, 1/2 hp I think without looking it up, which runs fine from single phase using the basic capacitor trick. In the home shop coolant isn't the most wonderful of ideas. Unless you get pretty serious about guards and deflectors its incredibly messy. I use a Bjur mister system.

Condition is everything. For the sort of money you are talking about the beast should be in good, unabused, condition with everything working as it should. Downfeed gears are a bit fragile, that seems to apply to all turret mills, but breakage generally indicates lots of use or abuse. The overload clutch is effective. Power down feed is really intended for boring not serious drilling.

Despite the internet reputation the varispeed versions work fine and last well but when they give up they have to be fixed properly. Step pulley heads can be bodged up with string and sealing wax if you accept sort of nearly works as intended. That said a step pulley head with a compact VFD mounted up on the head using only the middle two belt steps for pretty much all work does make a nice machine. Otherwise a varispeed is better. Especially when you get the job that insists on chattering unless the speed is just so. As I did this afternoon.

Clive

Clive, try as I might with the fitted coolant pump in my BP (1/3 hp?) and no matter what capacitor configuration I attempt it just wont run, drive it from an inverter and off it will go, what kind of capacitor setup do you use to run yours?

I have a couple of these pumps and both have the same issue.

Paul

Chris,

When you have a chance; would you be so kind as to post some photos of your F3

Aciera machines are "objects of desire" for both their build-quality and their enormous versatility.

[anyone who does not understand why ... just look at the first picture on this page]

MichaelG.

Only my opinion but a Bridgeport is the machine to have. Mine is the varispeed head and I have had no issue. Usual things apply, keep it well maintained and it will perform faultlessly. A friend of mine has also got one and his was noisy compared to mine. There is a plastic/nylon bush that fits around the top part of the quill top that wears. He replaced it along with the bearing that it sits on for little money and now its silent. I spent a bit of money on my own replacing the handles and knobs etc along with nickel plating a number of external steel components. Partly because I'm completely OCD when it comes to this sort of thing but I wanted it to be perfect and now it is pretty much there. It's a great machine to use and it gets loads of use with all sorts of jobs. Like all these things you end up spending on all the extras. I bought a traming tool from Edge Technology to set the head perfectly and all sorts of bits. I'm going to buy a multi angle vice next for those occasions when you simply can't hold a job in a normal vice, but that's the fun of having a mill I guess. There is always something to buy or upgrade.

Shop around before committing to buy, there are some really keen deals to be had. I paid £2000 for mine and it's like new, no wear or damage.

Good luck, send us all some pictures of your purchase when you get one.

Paul

Sorry I can't help you directly with the static converter capacitor trick to run a Bridgeport coolant pump motor as I run my Bridgeport from a 10 hp "whole shop" plug and play inverter from Drives Direct. I don't use the coolant pump anyway as I'm not set-up to contain the mess. A Bjur spraymist system generally meets my needs although it has its tempermental moments whereupon semi-coherent fury is a mood understatement.

However I have converted a few tens of three phase motors to run from single phase using capacitors in the 35 or so years since I bought a "how its done" diagram from, I think, an ME advertiser. That diagram showed how to do the trick with a Y, 440 volt, connected motor provided you could get at the centre star point. Haven't seen it for years but I imagine its filed away somewhere. Subsequently I used the data in the book "Electric Motors" written by Jim Cox to create my own automatic start capacitor switching version for delta connected, 240 V, motors which worked well and made a bit of extra toy money. I don't recall any motors under 1 1/2 hp failing to work but 2 hp and up could be iffy and only attempted under serious persuasion. Certainly had coolant pumps through my hands but what the source machines were is beyond recall, assuming I ever knew. I don't do that sort of thing anymore but if you like I could have rustle through the paperwork and see if there is any information I have but you don't.

Cive

Clive thanks for the offer, I have been through both of the late Jim Cox's books and another from the Workshop Practice series by Graham Asterbury and I have scoured the web for a solution to these particular motors and also like yourself have purchased schematics/plans too.

I have converted quite a few motors from Star to Delta and even the more unusual 6 pole things dont pose as much of a problem as these fractional Bridgeport ones.

I can only surmise that they must be wound in some peculiar fashion as to not be suited to capacitor running.

Regards

Paul

Can't help with the sizing Chris as I didn't buy one in the end! I was offered one in good condition about twelve years ago for a really good price but it was just too big. It would have fitted in the workshop but would not have left much room around it. Moving a ton of machine was also going to be expensive. Can't remember the table size except it was big - exactly what I wanted at the time! If you need a large table then they're a good option if you have the room. As nice as they are though I'm not sure it's Aciera quality. These days if I had the money I'd get a late toolmakers mill if I could - a nice Aciera would suit me fine...

"I may just put a bigger motor on mine and raise the head. I had assumed the Bridgeports were much more powerful."

You may not benefit much from uprating the motor. They aren't rigid enough to be able to tolerate significantly higher loads, so the only way you'd get to use higher spindle power would be by increasing the spindle speed itself. However, although the bearings might tolerate that for a while, they're not designed as high speed machines (balance etc) and the std pulley ratios aren't conducive to achieving that either.

With a VFD you can operate a std motor at higher than standard speeds, albeit at lower power. However, you may struggle to get all that power through a small (= high speed) cutter anyway. High power will most likely be required for hogging (ie bigger cutters with lower speeds and higher loads), where rigidity will be the limitation.

There are quite a few BP-derived machines that are more rigid (larger!) and more powerful. However, you can achieve a pretty respectable metal removal rate with the right cutters, speeds and feeds on the std BP machine. Depends what you are trying to do.

Murray

I read through all the replies yesterday as I went to look at a Bridgeport.

Thanks.

It it was quite a cheap one and probably not for me.

In response to the post above, my Aceira only has the high speed head which has a tiny belt and it slips under load.

The only speeds it can do are: 1000, 2000, 4000, 6000. The purpose of upgrading it was to use a VFD so I could vary the speed more. But as the belt was the limiting factor it made sense to change to bigger pulleys and belt. Then it made sense to also change the motor as the 0.5hp one would have been underpowered for it (possibly).

Increasing the head height I believe is a very simple job. It would raise it by around 4" and only take a couple of hours work, without affecting the machine being used at the standard height. It would only take a few minutes to change between heights.

Still undecided!

Sorry, I misunderstood. I thought you were proposing to uprate the motor on a BP which sounded questionable.

Without seeing what your Aciera head looks like, I assume a vee or poly-vee belt would be more than man enough. I'm a VFD preacher myself and like you I'd take the chance to uprate the motor if you are going to the effort of changing belts and pulleys.

Murray