Blimmin' 'eck! (Bridgeport milling machine)

[AdeV73]

After this weekend's coppery adventures, today my "new" Bridgeport mill arrived 

They're a bit bloomin' heavy, aren't they? Thought the fork-lift (that I'd borrowed) was going to blow a gasket moving it around. Still, it's there now... so time to get milling Hmm, after I've sorted out the power... and some tooling... Doh.

Happy days 

[panaceabeachbum]

congratulations,  Bridgeports (and clones) are the single most versatile machine you can own . I dont use mine alot but when I do nothing can compare for the huge number of setup options avail.   About 20 years ago I watched a fellow set up a small block ford engine on a bridgeport , he decked the bloc, bored the bank of cylinders , rotated it and machined the other side . Then using angle plates he hung the block off the side of the table, swung the head around and bored the cam bearings . I have had a 4' long cannon barrel hanging of the table of mine.  You can also see the 2" brit mortar bbl hanging off the table in my "heat engine " thread


Keep us posted

[AdeV73]

I'm right at the front end of a reaaal steep learning curve, I think. Thanks to GuyFawkes, I've watched some very informative "How to Mill" videos, which have given me loads of information to start off with; and I'm slowly buying measuring tools (we've got a semi-permanant postal strike on at the moment, it's causing havoc with my dial gauge deliverys...

A couple of Q's to those with - or who know - Bridgeports... (it's a 16-speed belt-change BJ2 head with 42x9 table)

1) I measured the "T" slot (narrow bit) to .610" - does that mean I should buy a 5/8" clamping set? I've got 2 t-nuts that came with the machine (supposedly holding the vice on, but only one actually has a stud & bolt to go with it...) which also measure ~.610". In French, that's 15.5mm; which seems to be a suspiciously round number; wheras .610 is a full .015" away from being 5/8". Worst case scenario, I can always machine down an over-sized T-nut I guess.

2) The blasted thing is in French (i.e. mm measurements, not inches). I'd hoped it was going to be Imperial, but clearly it's too new for that. I'm guessing that converting it to inches will involve new dials & leadscrews all round, plus a new dial/screw for the quill stop? That's not necessarily a disaster for me, as there's a fair amount of backlash (1/2 handwheel turn on the X-axis) - so this is clearly a machine that's been worked hard, and replacing the leadscrews with un-worn examples would be a nice thing to do anyway.  Meantime, I can use the DRO in inches, except on the Z-axis of course. I guess I will have to learn maths.

3) It has a coolant system   Presumably any water-based coolant will work with this; although initially I'll probably just use my spraycan of red cutting fluid. Would this cause contamination in a water-based setup, if some did get into the sump?

I'm sure there'll be many more questions in due course. I'd probably be best joining a machinist forum - any suggestions from the panel?

[panaceabeachbum]

Yep 5/8 tnuts would be correct , use-enco.com often has the sets around $40 and quite often has free shipping  . A little oil in the sump wont hurt anything , It floats and you can skim it out thru the access cover in the back of the machine. 

As far as backlash if you pull one of the handwheels and dials off you should see a pair of spanner nuts that are used to preload the thrust bearings and take some of the backlash out.  Also move the table al the way to one side and shine a flash light in the saddle, some machines use a split nut that has a flat head screw that can be adjusted to eliminate some of the back lash at the nut .  My machine also has adjustable gibbs so I can tighten things up.

Unsure on the dials. You might take a dial indicator and after turning a couple of revolutions to get the back lash out measure exactly how far the table travels for one revolution of the handwheel.   Mine travels .200" per revolution . I know dials are avail , the centroid company that does cnc retrofitts used to sell new pull off dial sets cheap on ebay

[panaceabeachbum]

cnczone.com has lots of useful info, as does practicalmachinist

 The water soluble oils give some really nice surface finish on the alum parts I make but they do breed bacteria like mad  and have to be changed regularly, about every 3 months here in FL . I like oakfflo dss70 , its a synthetic and I havent had any odor problems in the 1.5 years since I made the switch , I have not had to change it like I did with the oil based, just keep topping it off with water to replace what evaporates and add more concentrate as needed.

Jens is right it wont be long until you start thinking cnc or at least a nice dro and forget the handwheels all together.

The Mach software is great pc based cnc software and can be configured for just about any machine , I currently use it on all three of my lathe, the bridgeport and a 5x10 plasma table, really good help forum also

[AdeV73]

Thanks again guys, for the great info. It's much appreciated 

I think I may ignore the flood coolant system for the moment; I've got some oil in a can for steel, and WD40-a-plenty for ali.

I'll go looking for backlash adjustments tomorrow, if I get time. I can't do much more until I the machine wired up to some power; end of the week I'm hoping.

One of the dials (Y-axis) just spins uselessly - it looks like there's supposed to be a "biscuit" or gib key in there, but it's missing, so the dial has nothing to hold it's centre in relation to the lead screw. Does anyone have any idea what size & shape this thing should be, or should I just find a Bridgeport dealer & buy a new one?

WRT CNC/DRO: I have the Heidenhain DRO (seems to be a standard Bridgeport fitment, at least here in the UK, as it's mentioned in the manual) on the X & Y axes, but nothing on Z. It would appear, however, that the machine has mainly been used for plunge milling/drilling, as the Z-axis appears to be pretty tight with very little backlash - the quill, however, falls of its own accord if not braked (grr - any way to fix that without expensive surgery?) I've yet to test out for movement in the quill & other issues, as I don't have a suitable mount for my (only - so far) dial indicator. Mind you, I've three more dial indicators in the post, and none of them come with quill mounts or bases... I don't seem to have a collet small enough to hold the one indicator I do have. More curses....

I'm definitely considering CNC'ing it, but I'm going to need to reduce the backlash & other slop before I tackle that project for real.

[AdeV73]

I plan to add some of these to my machine:

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=350225588332&ssPageName=STRK:MEWAX:IT



I'm guessing that the best way to fit them would be to make up a fitment which clamps to the end of the dovetail on each slide, then screw the swarf cover into that; rather than making & tapping holes in the machine itself... any thoughts much appreciated.

[compig]

They're a bit bloomin' heavy, aren't they? Thought the fork-lift (that I'd borrowed) was going to blow a gasket moving it around.
Happy days 

You have a CS and are surprised how heavy a Bridgeport is ??!!

[xyzer]

One of the dials (Y-axis) just spins uselessly - it looks like there's supposed to be a "biscuit" or gib key in there, but it's missing, so the dial has nothing to hold it's centre in relation to the lead screw. Does anyone have any idea what size & shape this thing should be, or should I just find a Bridgeport dealer & buy a new one?

If you can make one why call a dealer. There should be a nut on the end of the handle and the handle is keyed to the screw. Pull the handle off and see if the dial is missing its key. Just in case you don't know the dial can be locked in different position to change your zero setting. If they arn't locked they can spin like you describe. They usually have a jamb nut in front of the dial so you can lock it at a new zero. As far as metric screws go I would live by my dro. If they are metric screws you could make new dials that would give you the proper divisions in inches. It may have inch screws and all you need are dials in inches. X 1 turn=.200" Y 1 turn=.200" Z 1 turn=.100". If your quill drops or does not return there is a flat spring on the oposite side of the quill handle under the cover that may need adjustment or replaced.
Dave

[AdeV73]

If you can make one why call a dealer. There should be a nut on the end of the handle and the handle is keyed to the screw. Pull the handle off and see if the dial is missing its key. Just in case you don't know the dial can be locked in different position to change your zero setting. If they arn't locked they can spin like you describe. They usually have a jamb nut in front of the dial so you can lock it at a new zero. As far as metric screws go I would live by my dro. If they are metric screws you could make new dials that would give you the proper divisions in inches. It may have inch screws and all you need are dials in inches. X 1 turn=.200" Y 1 turn=.200" Z 1 turn=.100". If your quill drops or does not return there is a flat spring on the oposite side of the quill handle under the cover that may need adjustment or replaced.

Hi Dave,

I can't make one until I know how big it's supposed to be - and if it's only a couple of quid from a Bridegport stockist, then it would make sense to just buy it...

I'm aware that the dial can be locked (thanks to Darrell Holland's "Vertical Mill" videos), what happens with mine is, if I undo the nut & take the handle off, I can then spin the entire dial assembly including the hub. If I withdraw the hub, it's obvious there's supposed to be a key in there to stop that hub assy from rotating.

Ta for the quill info - I'm not sure which cover you're referring to: Left or right side of the head? If the left side, I can't see any cover there, except the quill feed speed adjuster & the feed engage clutch cover, and I can't imaging popping either of those off will give ready access to the quill spring... Worst case scenario, I could always CNC'ify the quill, so it'd hold on the stepper motor.

My guess, as this is an British machine (destined for Britain, rather than made in Britain, I suspect) from the mid '80s, that it's all metric underneath. The X & Y dials are calibrated from 0 to 5.0 in 0.2 steps (5mm, I assume, i.e. .197" - that's pretty close to the standard .200", but not close enough). The Z is simply numbered 0 to 99 in steps of 10; I'm guessing that's 100ths of a millimetre, rather than thous., but I could be wrong.

[AdeV73]

Hmm, I actually have a plain "J" head (belt change), not the "2J2" which seems to be the varispeed, according to the book... Dunno if that makes a difference to the quill feed?

[xyzer]

Ta for the quill info - I'm not sure which cover you're referring to: Left or right side of the head? If the left side, I can't see any cover there, except the quill feed speed adjuster & the feed engage clutch cover, and I can't imaging popping either of those off will give ready access to the quill spring... Worst case scenario, I could always CNC'ify the quill, so it'd hold on the stepper motor.

I went out and looked....The spring is in the assembly on the right side! Inside of the flange with the shaft coming out of it with the screws top and bottom.
Sorry bout that!
Dave

[AdeV73]

Ta for the quill info - I'm not sure which cover you're referring to: Left or right side of the head? If the left side, I can't see any cover there, except the quill feed speed adjuster & the feed engage clutch cover, and I can't imaging popping either of those off will give ready access to the quill spring... Worst case scenario, I could always CNC'ify the quill, so it'd hold on the stepper motor.

I went out and looked....The spring is in the assembly on the right side! Inside of the flange with the shaft coming out of it with the screws top and bottom.
Sorry bout that!
Dave

No prob, & thanks for looking. As it happens, I just found the relevant bit in the manual! So, I shall try adding an extra 1/3rd turn of tension, if possible, and if that doesn't fix it, I'll have to buy a new spring.

Thanks again!

[AdeV73]

OK... that explains it. The whole spring housing & the spring itself are both missing! Oh well, at least I know what to buy now!