Bridgeport

[Jo]

Having had a very nice Harrison Milling machine for a number of years I keep getting desires for a Bridgeport to go with it. They seem to be getting remarkably cheap at the moment......

So: Having never had experience in a machine shop is this the right milling machine to be looking to add to the workshop? Or is there something else I should be investing in?

Also does anyone know the dimensions of a Bridgeport? (and the wieght... do they split down for transporting?)

[3405jimmy]

Ideal if you’re building in 7.25 gauge or bigger. If you can think of it you can probably mill it on a Bridgeport. Always loads of spares, tooling and attachments turning up on eBay so lots to spend your hard earned on.

Although it’s a fair sized machine its more finesse than brute force so put the 6” mill away and forget the ½ deep cuts.
I brought mine in on a flat trailer lifted it off with one of them car engine lift cranes you can hire and rolled it into the workshop on some 1” gas pipe cut offs

jim

[Steve M. W]

Like 3405 I shipped mine on a trailer and lifted it off with a engine lift but had to let the tyres down to get it clear. You are lifting 1 ton so keep well out of the way mine is 3 phase running of a transwave converter, you can get some more information from www.lathes.co.uk or I have seen the manual on CD for sale on Ebay.

Steve

[chris vine]

I have used a little Harrison mill for some years and it is very good. However one of the best advantages of the bridgeport is that they have an R8 spindle taper, (the Harrison is int 30)

The good thing about the R8 is that you can get collets very reasonably which draw direct into the spindle nose. This means that you can hold all end mills up to a size, with almost no overhang at all and with very good concentricity.

I have an idea that some older bridgeports might have been made with a different taper?? Someone on the forum will know better than I. but think the R8 is probably best for our type of work...

Chris.

[roger]

I have to say it's the best purchase I made.

Roger

[3405jimmy]

Jo,

I was looking in my old Bridgeport manual which gives some size you may find helpful. You need a cube of space 2.235M wide X 1.6M deep X 2.145 high to fit the machine into. The actual floor space of the base is .932M X .610M. The weight as Steve said is about a ton. The 48”X 9” table machine has 36” of travel

My book gives specs for the BRJ, BR2J2 and the BRM models. If you want I could scan the pages and send them to you, just drop me a private e-mail of your address

Jim

[Jo]

I've just been out with a tape measure. Wow! that is a bit bigger than my old Harrison. But with a tweak and a shove, it will fit. And I can keep the Harrison or the shaper in the warmth.....hummmm..

Next question... Which one is which (cost effective/worth having)? G&M have currently got a 2(?)hp MK 1 Varispeed with a 42" table. But there has been a few foreign copies... Are they any good?

[3405jimmy]

Jo,

I know nothing about the foreign copies buy like everything I am sure there are good and bad. I would go for some version of the varispeed head which I believe all start 2J. I think the BRM heads are belt speed change jobs but I have never seen one.

In our game I think the 42 or 48 inch table should be fine, remembering if fitted with a Bridgeport auto feed you loose about 3” of travel.

On the subject of power feeds don’t worry if your chosen machine does not have one you can buy Align units on eBay for any axis at £210 which is a good price.

Some machines come with a one shot lubrication system to all slides. Which sound great and is nice to have but it’s hardly a hardship to use an oil can for lubrication. Some machines also have chrome slides I assume to reduce wear but I have never been able to see the difference.

Also worth considering is Terry Braithwaite can rebuild or repair anything on a Bridgeport so it’s not like your buying something without a safety net.

Make sure the head runs quietly and there is no bearing whine when you cycle the quill up and down. Try and get one with a table is reasonably free from drill holes cutter indents and general dings. Obviously backlash and slide wear are also worth considering but unless you get an out an out production machine. They are morel likely to be out of adjustment as opposed to worn out.

They are always coming up on eBay and I have seen some very nice examples go for not bad money. In ME they seem always to be in £1750 to £2750 range with the odd one over £3K. There are four on eBay this morning one of which does not look a bad punt and it has a DRO fitted.

Anyway just my opinion and always open to contradiction good luck
Jim

[davidimurray]

Hi

I've used a number of bridgeports of the past few years. The brilliant thing about them is their versatility - but this can also be a pain. Because the head can tilt in so many directions getting the spindle square to the table can take quite a bit of time with a clock. Of course if you never want to do this then you are better off with a conventional machine. A friend of mine uses an archdale for all his 'normal' milling but has a bridgeport hidden in the corner for those special jobs. For us ME types I would say that a bridgeport is an ideal machine.

Try and find a machine with a varispeed head - they save so much hassle! Also if you can try and find one with a variable speed power feed - these are very handly as they have a 'rapid' button. The alternative is a 12 (i think) speed mechanical (the speeds are set mechanically but it is still powered by a motor) power feed.

If you have the chance also consider trying to get one with a DRO!

You may also want to consider what accesories you may want. R8 collets, drill chucks, an autolock (R8 only goes upto 20mm/3/4", autolock holds 25mm/1") chuck. Slotting head, right angled head, universal head, column rising block, horizontal attachment etc.

With regards to moving them, if you can try and use the lifting eye (there is a hole for one on the 'overarm') it is so easy to move. I moved one last week using a forklift and it was extremely easy. Being so top heavy I suspect it might be quite easy to turn one over if moved from the bottom.

In terms of trying to get hold of one try your local university/school/college. I've heard of good machines going for £200 as these places tend to want to simply dispose of the machine as quickly as possible.

Let us know how you get on

Cheers

Dave

[Roger Mason]

Hi Dave,

I see that you recommend the varispeed head for a Bridgeport.

I am slowly installing a Bridgeport that I acquired a little while ago, which is fitted with a varispeed head. I don't know what the previous users had used the machine for - I suspect nothing for many years. I have had to spend sometime in getting the worm and wheel that alters the varispeed speed cleaned out. The grease that it had been packed with was the consistency of a hard wax mixed with hardened clay! It was almost impossible to turn the hand-wheel, and hence adjust the speed.

I have discovered that the hand-wheel has a friction clutch built in to it. I have got this functional, but now there isn't enough torque transmitted to actually adjust the speed. Is this a well known problem? Should I just adjust the grub screw until the clutch cannot slip?

Incidentally I have only just got the motor wired up and it makes quite a racket when running. Is this likely to be the motor bearings, or other bearings? It is unlikely to be the quill bearings because it makes the noise even when in neutral.

Any advice gladly received.


Cheers,


Roger Mason, in a murky St. Agnes.

[JohnP]

Roger,

There's a pdf of the Bridgeport manual lurking around on the net somewhere. I you can't find it I have a copy on my hard disk at work.

Let me know if you want it.

Regards,

JohnP

[davidimurray]

Hi Roger

Can't say i'm an expert on the innards, the only time I've had one apart was to fix the quill feed. A friend of mine replaced the quill bearings a while ago on his so I will ask him. Some of the boys in the workshop might also know so I will pop down at their tea break and have a chat.

Apologises if you know this already but are you aware that you should NOT turn the varispeed handle without the machine rotating.

Can you lift the motor out? With the machine in neutral I think it would still be spinning a layshaft.

Continue typing - part 2 - just been down to the workshop and had a look through some exploded drawings. In neutral, the layshaft should still spin. There are two bearings on this shaft.

With regard to the varispeed. It would seem to work as follows. The handle operates the worm and wheel. At the back of the wheel there should be a pin. This is connected to a plate that is pivoted at one side and sits above the split pulley on the shaft. The plate is then linked to the pin. As the handle is turned, the plate is pulled down, this squeezes the two half of the pulley together. This then pushes the belt further out. Having had a chat with a couple of guys in the workshop they suspected that bearings are the most likely suspect.

Removing the motor doesn't seem to be that easy. I would suggest that you try and get hold of a bridgeport manual. Alternatively I may be able to take some pics of the manual down in the workshop if it helps.

Let us know how you get on!

Cheers

Dave

[davidimurray]

Just had a chat with another friend of mine. Apparently the friction clutch is a safeguard to ensure that you cannot turn the handle while the machine is NOT running. Hence if the handle works perfectly when the quill is turning then you should be ok, else tighten the grub screw on the detent until it works.

Depending on the age of your bridgeport, what type of head do you have, the motor may or may not have oil cups for the bearings- earlier ones apparently have oil cups for the bearing. An alternative to check is that the quill feed is not partly engaged or been messed with. My friends bridgeport made an awful racket when he first got it. It turned out that the quill feed knob had been whacked, which had displaced the bearing inside. As a result the gears were in semi-mesh resulting in a horrible noise!

Cheers

Dave

[davidimurray]

Me yet again - I'm realising how little I know about these machines I use almost every day!

Of general interest to everyone mya be this site :-
frugalmachinist.com/bp1j.html

Note that below the pulleys the workings would appear to be the same.

Cheers

Dave

[Roger Mason]

Hi JohnP,

Yes, I have a pdf copy of a Bridgeport manual. Although it shows details of the varispeed device it is not quite the same as mine. I have a feeling that mine is an older version - it has the round, circular disk on the front to indicate the speed, whereas the one shown in the manual has two small cut-outs to allow the speed to show through.

Hi Dave,

You said: Apologises if you know this already but are you aware that you should NOT turn the varispeed handle without the machine rotating. Yes I had realised this. In fact before I had the motor wired up I had thought that the stiffness in the control knob was caused by the machine not running. This was not the case.

Removing the motor doesn't seem to be that easy. I agree. I haven't tried it yet. I would not be able to lift it out like the manual shows - not enough room to rig up any kind of lifting device and I certainly couldn't lift a motor of that size. I have ideas about turning the head upside down and dropping the motor out, carefully controlled by resting it on the table (suitably protected).

Apparently the friction clutch is a safeguard to ensure that you cannot turn the handle while the machine is NOT running. Hence if the handle works perfectly when the quill is turning then you should be ok, else tighten the grub screw on the detent until it works. Guess a bit more experimenting is called for.

the motor may or may not have oil cups for the bearings There doesn't seem to be any way of lubricating the motor bearings. The noise could well be coming from this source!

Note that below the pulleys the workings would appear to be the same. It is not clear to me, from the drawings, how the back gear is engaged. What is that is moved when the gear change lever is moved? The drawings also show some kind of helix on the main shaft where the bull wheel (can you use terms borrowed from a lathe?) sits, I have no idea what this is - any ideas?

To all of you who have answered my queries many thanks.


Cheers,


Roger Mason, in a bright, cold and sunny St. Agnes

[Jo]

Just thought I should bring you all up to date. Whilst I have not had to put my hand in my pocket (success!!!) I have acquired use of a very well equipped Bridgeport, as last friday my next door neighbor brought one off Ebay.

What are friends for, if not borrowing their milling machines?

[davidimurray]

Roger

Spent a bit of time looking at the manuals and pondering it over with a couple of friends and think we have figured it out.

The manual I have is marked Bridgeport Textron - a friend has an adcock and shipley one which shows some different drawings (I haven't seen them but they apparently show how the backgear works ). Note that the Bridgeport textron manual shows the change gear handle at 90 degrees to its actual position on the machine. The head I am looking at is the 2J2 head. Which is the slightly later head with the extra cover plate over the varispeed head with the two windows.

Now to how the backgear works - I will put the terms used in the manual in brackets. In the plain head, the small backgear pinion (bull gear pinion, 83) is lifted by a selector fork to change gear. However on the varispeed head this is completely different. Here the backgear pinion (bull gear pinion, 83) remains in the same position. The gear actuating arm (bull gear shift pinion, 59) has a gear cut on its end. This engages with a rack on the back of the 'spindle'. When you turn the backgear handle (hi-low shift crank 70), it lifts the whole spindle arrangement, resulting the the main gear (spindle bull gear 40) being lifted out of mesh with the small backgear pinion (bull gear pinion, 83), and then as it is lifted further, the dog clutch on the top (splined gear hub, 39) then engages with the main drive (spindle pulley hub, 37).

So when you are in 'high' speed the spindle will be lifted up, the dog clutch engaged and the main gear will be lifted clear of the pinion gear. the pinion gear is driven by a timing belt from the main drive so it will always be spinning.
Conversley, when in backgear, the dog clutch will be dropped down and the main gear will engage. In neutral neither will be engaged, but the backgear pinion will still be rotating.

The helix shown is for the quill feed drive.

Roger, what sort of noise is machine making ? Do you happen to have a stethoscope that you could use to listen to each part of the machine. I could possibly take a sound recording of one of our varispeed machines and email it to you if it is any use.

Cheers

Dave

[Roger Mason]

Hi Dave,

Many thanks for all the effort you have gone to on my behalf.

The manual I have is just called "Operation and Maintenance Manual (Including Spare Parts Catalogue". Judging from the spelling of that last word I guess it is an English manual (Adcock Shipley?).

I pretty much follow what you are saying, but I am a little confused between the quill which moves up and down as for drilling, etc. and the part No.39 which has the dog clutch on the top and moves up and down to engage the different speeds. You say the helix on part No. 39 is what the pinion on the drilling handle engages with to move the quill up and down, but wouldn't that move the dog clutch in and out of engagement?

what sort of noise is machine making ? To be honest I haven't got the machine wired up properly yet. I have run it a couple of times with a bit of a lash-up. The next project is to wire up the control unit for the inverter, then I can control the motor without standing on a stool and reaching rather dangerously over the mill. When I have got it working I will attempt to describe the noise from the unit. I think a lot of the noise is actually coming from the belts - they are possibly very dry and possibly very old. The pulleys look as though they might have some surface rust on them - could make for funny noises! I might try taking the spring pressure off the main belt by putting the two screws in the spring loaded pulley as described in the section of the manual dealing with removing the motor. That ought to tell me something about the noise if it is coming from the main belt.

Again many thanks for your assistance.

[Alan]

Hi.

Who is 'Terry Braithwaite' who can fix anything on a Bridgeport.

I am looking for help in the South East Enland area.
My autofeed needs looking at.

Alan

[lancelot]

Hello Alan,
contact details...
Terry Braithwaite...

www.braithwaiterebuild.co.uk
01262 606691
[e-mail]

All the best,
John.