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Member postings for Clive Foster

Here is a list of all the postings Clive Foster has made in our forums. Click on a thread name to jump to the thread.

Thread: Bridgeport Series 1 Mill Feed Box
21/11/2017 23:47:38

This appears to be the same as the picture in the parts section of the 1966 manual that I have :-

**LINK**

This seems to be about the only potentially useful discussion that comes up on a Google search :-

**LINK**

Couple of pictures of the innards can be found on line.

Clive.

21/11/2017 22:32:05

George

I have a pdf copy of the 1966 Bridgeport manual which has internal details of the feed box in the parts list section. Not as clear as the later parts book pictures due to the original being excessively reduced but, I think adequately readable if printed to A3 size rather than A4. PM me and I'll shoot the file over.

I also have a brand spanking new X axis feed screw for the gearbox power feed model. Possibly the last new one in captivity, on this side of the Atlantic at least. I can make some measurements for you to confirm sizes before you make your own or we could do a deal for £ very reasonable. Obtained over 15 years back for a mate who changed his mind when he realised that I seriously wanted him to pay for it!

There is probably some useful information on the Yahoo Bridgeport Mill Group. As Moderator I ought to know but I've never delved that far into the older conversations. Nothing obviously useful in the files section. Probably worth joining up and asking if anyone knows.

Clive.

Thread: Phase convertor problems
21/11/2017 17:41:34

John

Short answer is I don't know. No experience of a system with one motor so close to the nominal maximum of the converter output. Really has to be try before you buy.

Fundamental limitation is how much current the step up transformer can supply. The transformer is considerably over-rated for load current because its supposed to supply the start up current surge without too much voltage drop so there should be ample headroom to supply the pilot motor. A 2.5 or 3 HP pilot will want around half a horsepowers worth of current. Its said that for best performance the pilot motor should be as large as, or larger than, the biggest motor but even a 2.5 or 3 hp one will give a very useful boost to the third phase of the lathe motor on start up.

The pilot motor ensures that there is properly synchronised 3 phase power on the generated leg even at start up so its much less current hungry than a static converter. More than enough saving to supply the pilot motor. Not only does a static converter effectively have to get going on only two phases it also has to fight the capacitor bank to some degree as it runs up as the third phase generated with the help of the capacitors is seriously out o sync relative to where it should be.

Clive.

21/11/2017 14:54:42

I'm impressed that Nathan is able to get a static converter running well on both speeds. Ones I've run into usually won't play ball. Either can get one speed going decently and the second one either not working at all / barely limping along or both clearly unhappy and not giving full power.

Got a 4 HP max MotorRun static way back when I first installed my Bridgeport from a guy who was selling it because it wouldn't run the two speed motor on his new-to-him lathe. Colchester I think.

Adding a pilot motor to make a static converter into a crypto rotary has always worked well for me when arm twisted into sorting problems for other folk. The old MotorRun ran my Bridgeport OK but never seemed very happy and changing settings was sometimes desirable when using larger cutters. Had a 5 (or maybe 3) HP motor about the place which I connected as a permanently running pilot. Transformed performance. Much happier running and a clearly faster, better, start. Sold by it mail order complete with pilot motor to a bloke who rang me up later to say how pleased he was with how well it ran the two speed motor on his Colchester lathe. Which was nice but, frankly, I'd have not risked selling it to him if I'd known it was going on a two speed motor.

Connection dance still happens even with a factory rotary. My mate Mike the Pilot has a Bridgeport on a Transwave rotary which will only run properly on one specific arrangement of connections. I'm pretty sure we tried the lot. Both motor and control gear. More than once. On wrong ones it either wouldn't go at all or stopped after a random few minutes. Even sensitive to which side was live and which neutral relative to the converter input. Which is seriously odd. Been working fine for getting on for pushing 20 years since we fixed it! So I guess its sorted well enough.

Clive.

Thread: Myford Correct Oils
21/11/2017 14:22:10

Although the ISO 32 / ISO 68 equivalent pairing was made 70 odd years ago its still perfectly relevant today. Viscosity, and its variation with temperature, essentially defines all the major parameters of oil behaviour. If something was designed and made to work correctly with ISO32 70 years ago then ISO 32 is what it needs today. That pair was, and is, a very common choice for machine tools. Development over the years has considerably improved the efficiency of lubrication in the machine tool environment and correspondingly reduced wear but if the machine still works best with the viscosity it was designed for. Not something probably inappropriate chosen just because one aspect of its behaviour looks good or is considered sexy by the puditaria.

If you seriously want to change the oil you also need to re-work the design to make best use of the properties of the new oil. Which may not be easy. In particular the effects of oil film thickness and shear rate on drag and lubrication / wear properties need to be quantified if any real benefit is to result. Modern car engines are an excellent example of the problems involved. These days oils are almost specific spare parts for each model. Heck even the same engine from the same factory may have different oils specified for different vehicles. Upside is extended oil change intervals and 200,000 mile plus engine life. Downside is serious wear if the wrong oil is used.

The main reason for oil all over the place on a machine tool is over-lubrication. At times I'm as guilty as anyone. Geo. H. Thomas who remarked on this concerning folks complaining about handing dirty, oily change wheels saying:-

"The amount of sliding movement of one tooth on the next is very small indeed and the duty light so so there is no need to smother them in grease or bathe them in oil. .... will leave you with hands like the village blacksmith. My gears ... they have only a thin oily film on them which is perfectly adequate for the duty performed and seems to stay there almost indefinitely." (ref "Dividing & Graduating, 1989 reprint, p23)

The stringing of ISO 68 between gears is merely observational proof of transfer down the gear train. Drip a little on the top gear and what it stringing down to the lowest one. Maybe little fling off into the tray if the drips were more splot but you will be good for the next year or so.

Similarly with headstock bearings. The SouthBend 9" is justly renowned for the long life of its simple direct in the casting headstock bearings yet these are simply fed by a wick wiper from small reservoirs. Actual oil consumption is tiny, mine used to see an oil can about once every 6 months.

One place where over-lubrication is probably beneficial is on the bed. I periodically squirt clean oil on, rub with a clean rag or pair towel and wipe off to remove any residues long before they have got to the gone off varnish stage. Do a similar wipe off before lubricating the cross and top slide ways. Tailstock too.

Clive.

{Poxy spell un-corrector!}

Edited By Clive Foster on 21/11/2017 14:23:31

Edited By Clive Foster on 21/11/2017 14:24:17

Edited By Clive Foster on 21/11/2017 14:26:03

21/11/2017 10:30:59

ISO 68 oils do vary in stickyness but my experience is that there is little, if any, difference in the ease with which well adjusted sideways move between a well chosen ISO 68 and ISO 32. Set-up and adjustment of sideways seem to be much more important. Its well worth taking few hours to get sideways and gibs properly clean and adjusted just so. In particular the varnish like deposit from oil , gone off, oil promotes stiction and upsets the clearances. Total PIA to shift. Especially if engine oil has been used. I think things react.

My Smart & Brown 1024 uses ISO 32 (Castrol Hyspin AWS32) for bed lubrication via a pump in the apron driven from the saddle longitudinal drive. So ISO 32 is clearly up for the job on a full size lathe as well as a model makers one. However it uses, relatively speaking, a lot of oil so refilling the apron is a regular chore.

Its also noticeable that the ISO 32 oil film dries out quite quickly. After a few hours of non use, certainly overnight, the saddle is clearly less free moving until its been wound back and forth a couple or four times to get some oil up. If I've not used it for a couple of days or more I anoint the bed with ISO 68 (Castrol Magna BD68) both sides of the saddle and along the bed where the hold down bearings run. Once the saddle has moved enough to get fully over the oiled section it seems just as easy to move as when relying on the ISO 32 from the pump. My P&B model B doesn't have an oil pump so bed lubrication is by manual anointing. Can't feel any difference between ISO 32 and ISO 68 as way lubricant but the ISO 32 needs more frequent application. The saddle clamp system on the P&W is a bit worn and doesn't quite come up properly tight. Its noticeably more grippy with ISO 32 than ISO 68.

One impressive property of ISO 68 is the way it strings between the backgears. They run quieter to than with ISO 32.

AS ever YMMD.

Clive.

Thread: Phase convertor problems
20/11/2017 11:17:36

Presumably its a rotary phase converter with a step-up transformer to give 440 volts and the contractor coils are correctly connected across the transformer outlets.

If so its under-rated for the job. Those two speed motors are notorious current hogs on start-up and if the transformer cannot supply the full current needs the voltage drops enough to let the contractors pull out. As soon as the contractors pull out full voltage is restored so they pull back in. Effect on motor is sort of like getting a dead car rolling by rocking it back and forth. After three or for chatters (rocks) the thing gets moving on the the current the transformer can supply.

Electrically savvy folk with appropriate knowledge, experience, understanding and instrumentation can sort such problems. Usually doesn't take a lot to go from almost works properly to does work properly, albeit with perhaps less safety margin than you'd ideally want. If you know what you are doing.

For ordinary guy in the shop best solution is brute force with a bigger converter. On home built converters enlarging the rotary element / pilot motor can fix the problem. Were I to do a home brew (which I never shall again) I'd probably use a 7.5 HP pilot and a theoretically oversize transformer.

Commercial manufacturers have to hit a sensible price / performance ratio so sometimes a device that works perfectly well for all normal use will fail for the edge cases.

If its a static converter basically fergedditt. Generally running such motors is beyond their pay grade.

Clive.

.

Thread: Myford Correct Oils
19/11/2017 18:34:17

Halfords won't have anything suitable.

ISO 32 hydraulic oil with anti-wear additives for everything except the slideways. Thats a basic hydraulic oil readily available mail order or from specialists. I use Castrol Hyspin AWS 32 in my (not Myford) lathe 'cos its what I can get easily and its done me fine for over 25 years but there are many equivalents from other brands. No need to pay extra for the fancy high temperature, anti-foam et al properties.

ISO 68 dual rated slideway / bearing oil for the ways and backgear train. Pukka way oil is too sticky for small lathes. Many brands but I use Castrol Magna BD 68. Excellent in the oil can for hinges and the "Honey Do" jobs too. Thin enough to flow (slowly) but stick enough to stay put for a year or more. But not in locks!

Clive.

Edited By Clive Foster on 19/11/2017 18:35:35

Edited By Clive Foster on 19/11/2017 18:36:06

Thread: Lever/Rack tailstock preferences
19/11/2017 18:22:52

Choice is six of one half a dozen of the other really. Lever is arguably better for small drills due to direct connection which is said to give better feel. Rack is arguably better for larger ones as it is said to give more thrust for the same force. As Richard says in practice either will do fine.

When using big drills you may well prefer to change back to the screw feed.

Clive.

Thread: Topslide setting jig
19/11/2017 14:14:53

Neat idea Larry.

Agreed that lathe designer rule 1 seems to be make the topside angle scale hard to read. All the ones I've encountered have been, ahem, "less than ideal" although usable enough if you make the effort.

Sidestepped that issue years ago by switching to the zero-to-zero threading method and never bother with setting an exact angle. Anything a bit under the proper angle will do as the lathe keeps track of all the pesky feed distance and thread depth calculations whilst the tool ensures the form is right by taking an appropriate skim off the almost non cutting side.

Actually my topside lives at 25° angle off which does for both 55° and 60° threads. Also keeps the cross and topside handles out of each others way an stiffens things up a bit on heavy cuts as some of the feed load goes through the topside dovetail. Win x4.

Clive.

Thread: Cheap Indexable End-Mill
18/11/2017 20:55:54
Posted by JasonB on 16/11/2017 07:25:15:
as do the 1" dia "Little Hoggers" also with triangular inserts but held to give negative rake.

#2 on the Little Hoggers. Noisy but work well on my Bridgeport and, previously, my Chester Lux style square column mill. Pity there still appears to be no proper advice on speeds, feeds & depth of cut beyond 5 X HSS and around 12" per minute. Fine on my Bridgeport but I suspect smaller machines will be struggling. As is so common with carbide slowing down for an easier life is counter-productive.

Old penguins like me can soon sort out what works and what doesn't but carbide first timers could do with a bit more help.

Clive.

Thread: Acetylene regulator / propane
17/11/2017 18:38:34

Hi Nick

Difference between should be and are.

I know for an absolute fact that the high pressure regulators on the white-spot nitrogen bottles I used at RARDE / DERA / DRA / QinetiQ were not changed in 20 years. Not new when I took the lab on and still there when I left. Pretty sure that the regulators on the welding bottles in the section workshop and those on the various gases the chemists used went lots longer than five years too. Not sufficiently intimately involved to be certain but pretty sure I'd have heard if they were. I do know of hoses being changed due to developing leaks from age but regulators left untouched!

Government (MoD) research establishment with theoretically hot safety department generating reams of paper , procedures and multiple inspections. All trivial and total waste of my time. Flag up anything serious and "no budget to fix" followed by "just get on and do the job from line management".

Research use is bit different from factory being mostly occasional short bursts rather than all the time so presumably an easier life for regulators.

Clive.

17/11/2017 17:28:28

A major concern when following "used it for decades with no problems" advice with modern components is that modern equipment tends to be much more specifically engineered than "good old stuff". Its frequently safe to assume that the lower end, economy range components will have given up and been dumped years ago so survivors tend to be of good quality. Production issues back in the old days may well have meant minimum changes to a standard design to cover a range of gases and applications was better than trying to make regulators specifically designed for each application. If this is the case the old design will be able to handle worst case, highest pressures, so the only issue will be whether the adjustment range gives sufficient controllability when fitted with springs for a different application.

More modern equipment is almost certainly engineered for its specific application so going outside what was intended is probably risky. Especially as the likes of us will probably be purchasing economy range components which perform well enough when doing what they were designed to do but don't have the safety margins to handle a different job. Economy gear is intended too be bought, used and thrown away after what might be considered a relatively short life so the engineering is appropriate for that.

Clive.

Thread: Sketch/Drawing holder
16/11/2017 20:47:59

#2 for the magnets and whiteboard suggested by Michael G. Whiteboard is handy for scribbled notes about things like cuts, co-ordiantes, calculations and other things I need to keep track of during the job.

Simple quick'n dirty stuff just gets ruff (very ruff) sketched and dimensioned on the whiteboard.

One whiteboard by side of the mill and one at the tailstock end of the lathe. After completion own design jobs stay in the wallets for filing in an A4 lever arch file after annotating for errors / changes which are subsequently copied back to the original CAD files.

Previously I hung drawings on the splash back like George. I found they needed an alloy sheet weight / stiffener in the wallet behind the drawings to keep them flat and stop them flapping. Bit far away for easy reading too when I moved up to larger machines.

I use a lot of those wallets. Just printed out my own personal copy of the Range Rover P38 RAVE electronic manual. No full spectrum printed manuals about and its so nice to have greasy finger proof versions. About a 3 ft shelf full of binders. Working on the parts book now.

Clive.

Edited By Clive Foster on 16/11/2017 20:48:13

Thread: Twisted lathe bed - Portass Model S
16/11/2017 20:31:02

Hi Steve

Just the removing the spindle will do. Essential as the test bar has to slide through the bearings as you move down the bed. Important that there is negligible play or shake.

The nice thing about this particular method is that it gives you the error between spindle axis and tailstock axis directly. Obviously if the tailstock axis and spindle axis are in line then the bed is true, assuming that the tailstock belongs to that particular lathe.

There are numerous ways of measuring the relative offset. If you have a decently sharp tailstock centre you could do a quick and dirty first run through using that and an a finely graduated rule to measure how far out things are. If your eyes are good or you have a magnifier you can probably estimate to better than a 1/2 mm (about 20 thou), maybe even 1/4 mm.

Clive

15/11/2017 19:49:57

Steve

Don't know of any references but, bearing in mind I've never done the job myself, a couple or three methods spring to mind.

You do need a accurate bar long enough to reach the end of the bed mounted up in the headstock bearings.

1) Probably the officially correct way is to clamp the headstock end to a surface plate with the tailstock feet (just) clear of the table. Fit a guide to the surface plate so you can slide the dial indicator mount along parallel to the test bar. Find a block close to the centre height of the lathe plus half the bar diameter to sit the indicator base on when measuring off the bar. Record the height of the test bar at suitable intervals whilst sliding the indicator mount along the guide. Repeat on both sides of the bed after removing the block. Lot easier to make the measurements on the bar if you have an elephants foot on the indicator, a disk maybe 1/2" to 3/4" diameter, instead of the usual ball tip. With a ball tip you need to go straight down the middle of the bar so the guide has to be just right. Elephants foot sits on the centre even if you are bit out. Difference in readings for both sides will give you the twist.

2) Clamp the lathe down on a bench by the headstock end so the tailstock feet are clear of the surface. Lightly pack the tailstock feet for stability. Put the indicator in an L shape carrier so that its tip is above the bar centre line when the upright is against the bar. Arrange suitable base so it can be sat on the cross slide and held down with the upright touching the side of the bar. Slide along and record measurements at suitable intervals. Repeat for other side. This way will also give you a good indication of any sideways bend in the bed.

3) Probably the way I'd do it. Arrange the bar so it can be slid though the headstock bearings. May need a bush for the front one if its smaller than the back. Fit the tailstock and measure the relative offsets of the tailstock quill and the test bar are suitable intervals along the bed. Obviously the test bar is slid though the headstock to meet the tailstock. Lots of ways of measuring the offset. Quick'n dirty is to butt the bar up against the end of the tailstock quill and hold a vernier or digital calliper at a shallow angle so it spans the gap. Better is to sort out some sort of overlapping tongue or a pair of pins in suitable clamps.

Method 3 can be lightly modified to give an excellent test for straightness by making a sleeve with different size bores each end one side a sliding fit on the test bar, the other a sliding fit on the tailstock quill. If you can engage the sleeve on both and slide it back and forth things are probably close to right. This is an exceedingly exacting test. Sliding with thou oversize bores at bot ends would probably be better than new.

Clive.

Thread: Article Suggestion "White Elephant & Why"
15/11/2017 15:30:35
Posted by Chris Trice on 15/11/2017 15:12:31:
This thread could also include simple accessories that punch above their weight i.e. that turned out really useful and get used a lot.

Good idea Chris but probably better covered separately in its own thread "Unexpected Angels" perhaps.

Your mention of DRO's is yet another side to the same sort of question, "Cost a Fortune but Worth It" maybe.

Really its all about getting the information together so that folk can make an informed choice about what is best for them given that what we do, what machines we have and how much money we can spend varies so much. My weakness is a tendency to lock on to particular solution or set of solutions and darn well make it work. Then practice my workshop esperanto when a much easier / better / cheaper / more versatile way is pointed out.

Clive

Thread: Twisted lathe bed - Portass Model S
15/11/2017 14:15:18

Steve

You have to map relative to the lathe spindle centre line. Fundamentally all the matters is that the bed is parallel to the spindle in all planes and that the tailstock taper is concentric with the spindle centre at all positions along the bed. Within appropriate tolerances and limits of course as perfection is impossible (unless you are dead lucky).

Everything else is pretty much in the wind and can be shimmed. packed or machined as desired so the beast sits properly on the bench.

Clive.

Thread: Article Suggestion "White Elephant & Why"
15/11/2017 14:04:58

There are plenty of ways in which a Model Engineer or Home Workshop person can waste money on things that look to be good idea but end up as a pretty much unused White Elephants or Cupboard Queens. For example late in the Lawerence Sparey thread the subject of tailstock turrets arose. The small one I have could fairly be considered a white elephant whilst the larger one is perhaps more very light grey or, at least, grubby white.

Leaving aside things that flat out don't work the reasons for white elephant status include :-

1) Doesn't actually do what I thought it would.

2) Don't actually need to do what it does

3) Can't accommodate it on my machine

4) Doesn't suit the way I work

5) Needs a bunch of other (expensive?) stuff to be really useful

I figure that a decent bit of forum discussion along the "My X is a white elephant" - "No I use X all the time with ... to do ..." could be distilled into a very useful article helping folk to decide where best to spend money on their particular needs. In particular the change in the price / performance / availability equation since I got my first lathe around 1973 means that I'd not advise somebody starting out now to do things the way I have. Equally I'm unlikely to change because I have all the stuff to do whatever my way and changing to now more appropriate approach isn't worth it.

Number 5 is the catch 22 for someone just starting out or with limited tooling with big potential gains if you plump hard for one way and set-up to use it properly. Like the aforementioned tailstock turret. But shades of the January Gym Membership purchase that mostly gets wasted because regular attendance can't be fitted in. Folk with large machine experience can get bitten by number 3. My solution was to buy full size machines!

Clive.

Thread: Twisted lathe bed - Portass Model S
15/11/2017 12:11:51

The main issue with simply bolting to s strong flat base to pull things straight again is that the amount of rectification twist applied along the bed will be inversely proportional to its stiffness. The basic structure is an I beam of varying section so the untwist will run along the neutral axis. Need to consider the leverage effects of applying force via the feet too. The weakest point is in the gap where the thinner centre section of the beam is relatively deep. The bed proper is of varying depth and of asymmetric section due to the wider shears so the neutral axis will be at an angle. The various asymmetries mean that the bed will want to shuffle sideways and upwards a bit too. Not much but significant in machine tool terms.

If the original cause was simply due to bolting down to a very stiff, relative to the lathe bed, flat bench with a twist in it then simply pulling things down to a strong flat plate should, eventually, reverse the effect. During the process the bed will of course be unnaturally stressed but thats hardly likely to affect its function on such a small machine. I think it unlikely that the original bench was simply twisted. Probably some flatness and tilt errors too so its anyones guess whether you can simply reverse the effect.

If its age distortion of an un-stabilised casting then reverse twisting probably won't correct the effect as the mechanism is different and where the error lies has more to do with mass distribution rather than stiffness. Probably need to do as Murray suggests and use a bonfire to remove most of the residual stresses before re-machining.

Proper procedure is to fit a long straight bar in place of the spindle, clamp the the headstock down securely to your surface plate and map out the bed bend both vertically and horizontally relative to the spindle centre-line. Preferably use a thick wall tube rather than a solid bar to minimise droop. Once you have a map you can decide what to do. If it is ageing twist you may be able to correct it on the main bed by clamping two heavy section bars to the ways at headstock and tailstock end and twisting.

Were I to attempt the job I'd simply replace the main bed with a heavy, bevelled edge, plate Hardinge style. Starting by machine the tailstock feet flat and fitting appropriate spacers before doing the main milling job. I'd probably not bother trying to de-stress or straighten first, figuring that its stable how it is, but would check for truth after milling and make appropriate adjustments to the tailstock end feed before a final skim.

More work than simply re-twisting but guaranteed to work and far less futzing about if a simple re-twist doesn't go right first time.

Clive.

Edited By Clive Foster on 15/11/2017 12:19:38

Edited By Clive Foster on 15/11/2017 12:21:27

Edited By Clive Foster on 15/11/2017 13:12:30

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