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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: Has anyone tried the 0um ER Adjusters?
23/03/2013 20:11:15

Ahem! ER collets don't hit the specified run out until they are torqued up properly. Which is a lot. 70 ft lb or so I think for ER-25. Nipping up by hand as shown won't do it. Nor will it hold the tool or whatever properly. That skinny ring and adjuster screws will do sweet FA if the thing is tightened up. As shown all its going to do is push the cap around so that the slack collet is square in the taper before you lean on the spanner. Very theoretically it might encourage things to settle squarer than they would if left to their own devices but in a practical world just pulling up tight does just fine unless there is a fault in collet or holder.

ER collets are, by design, aligned by the rear taper so there is sufficient clearance in the cap threads et al to allow front to follow back. Which it will do just fine provided the component being held is rigid enough not to crush and inserted far enough to fully support the fingers.

Clive

Thread: Drummond loop type pitman
23/03/2013 16:44:11

Very long time since I looked at anything like that but my recollection is that the pin was a nice sliding fit in and just a touch longer than the thickness of the pitman link. Large washer under the head of the bolt stopped things falling off but the difference between pin length and pitman thickness presumably stopped things binding up. So far as I know it all worked but my involvement was simply rooting through stores to find a suitable bolt and washer to replace the originals which had gone AWOL.

To save trying to thin the pitman down I guess a stepped, double diameter, washer could be made with the inner part a bit under pin diameter and deep enough to create clearance between the larger, retaining, part and the link. That would not to interfere with sliding.

Clive

Thread: CNC Router
22/02/2013 11:07:37

Now that relatively affordable bench top CNC routers are readily available and modern end mill cutter capability extends to warp speed and light cuts making reasonable metal removal rates are potentially possible on moderately stiff machines I wonder if its time to re-think the standard approach to model engineering machinery. Currently we go for the" tool-room but lots smaller" way which means a lot of gear and problems with stiffness / size / work envelope of machines (especially small mills). Imaginative, rather than industrial made small style, use of modern PC and instrumentation capability is also conspicuous by its absence.

Standard small CNC router moving gantry layout is fine for woodworking and co-ordinate drilling but stiffness limitations mean that its never going to be very good with metal. Once upon a time small, usually hand operated, planers were common and considered effective metal removing devices. So consider using CNC router components with a fixed gantry and moving bed planer style. Should be stiff enough for metal working. The CNC end won't care if the bed or gantry moves but probably needs servo rather than stepper drive to shift the table at adequate speed. Three heads high speed spindle for milling, drilling head and planer tool carrier. Drilling and planer heads do the rough work of getting close to size, milling spindle gets it right. Warp speed capable cutters are relatively expensive for home shop use so its silly to use them to excess.

Expanding on the concept consider a fifth axis, with tail stock if need be, to do lathe type work. With modern probes we don't need sub tenth thou removal and re-fit capability. So long as its close the machine can figure its actual position and work from there. For most ME stuff I suspect a vertical lathe arrangement would be appropriate anyway. Long stock? Hole in the middle of bed'n bench for up to inch is diameter should suit.

Makes a big investment seem bigger as its a one-time hit but could well be cheaper overall once the cost of piecemeal assembly of a full shop is added up. I refuse to add up what I've spent over the years!

Clive

Thread: Poor quality finish
18/02/2013 18:55:13

By far the best source of basic information on tool shapes and cutting speeds is section 5 of Model Engineers Handbook by Tubal Cain. Seven pages, seven effective tool shapes, good listing of angle variations for different materials and accessible speed'n feed information. You can go a long way before you need more. Copy, enlarge for easy reading, print and pop in a suitable transparent pocket book to keep in the workshop.

OK feed and cut data given is based on a Myford, relatively wimpy compared to your machine, but there is no shame in walking at Myford cut rates whilst you have the training wheels on. Easy enough to uprate the cuts to mach your lathe strength once you have got the hang of things. Naturally assuming the work piece is strong enough to take a heavier cut. Heavier cuts mean greater quantities of hotter swarf coming at you too! My work rate is set more by the amount, and heat, of swarf than by what the lathe can do.

Getting the cutting edge on centre height is very important. Some sort of gauge being essential. Quick and easy way is to fit a suitable piece of flat stock on a base of some description, stand it on the cross slide, and scribe a line across it using a sharp centre in (preferably) the head stock although tail stock will do. Heck if push comes to shove simply eying up against the tail stock centre will get you close for now.

I don't wish to decry the efforts of the many able contributors to the model engineering press and publications but, objectively, the tool grinding equipment, advice and techniques available to the lone hand novice is very poor. Most being cut down industrial practice which pretty much assumes the user has been taught. Way I see it a novice needs simple and reliable ways to consistently reproduce a few effective tool shapes and angles along with the requisite tip radius. Given the importance of tip radius and angle on cutting performance it really doesn't help progress if every re-grind produces a slightly different shape. I know of no published designs for easily producing different tip radii or of any method other than scales and temples for getting angles right. I have my own ideas on an effective system but, unfortunately, am completely incapable of writing them up for general publication. Too many scientific & engineering reports.

Clive

Thread: Cutting a non linear spiral thread
16/02/2013 18:28:13

Yup US National Bureau of Standards developed an attachment for 9" SouthBend lathes under contract to the Navy Aeronautics Bureau. Drawings can be found at **LINK** along with a lot of other SouthBend related information. Presumably to expand production of such components to meet wartime needs by exploiting the large number of SouthBend and similar machines in schools and training establishments.

Specialist machines do it differently. One way is by chasing using a non linear master. Another is to fit a matching feed screw to the slide of a standard precision bench lathe driving in the usual manner through a shaft from a gear train. Far as I know the mould makers lathes with sliding lead screws can only do linear pitch changes .

Clive

Edited By Wolfie on 17/02/2013 13:35:21

Thread: Building an engine bigger than designed
15/02/2013 21:25:33

Usually not a functional issue when scaling up but its wise to keep an eye on the strength / stiffness aspects of components. At smaller sizes components often have to be thicker or of larger than "scale" size to ensure that they are not too floppy to function well. The fixings and screw sizes used are often relatively oversize too so that ordinary range threads etc. can be used rather than the super weeny watchmakers versions.

By reason of familiarity such relative over-sizes can be seen as perfectly acceptable on a very small model but if carried over onto something rather larger ( i.e small model) the effect can be jarringly wrong. I've no idea where the line between very small and small falls but I'm sure we have all seen examples of nice work being wasted because such things ensure that it will never look right.

Clive

 

PS Neil types faster!

Edited By Clive Foster on 15/02/2013 21:26:26

Thread: Bandsaw Problem
14/02/2013 14:16:51

My Alpine H/V bandsaw suffers similar start problems on a pretty regular basis. Certainly centrifugal switch in this case. Done the strip'n clean fix a few times but it never lasts more than a year to 18 months so I now just whack the thing when it hums jarring the switch into working. Not exactly inspector meticulous engineering but its been successful for getting on for 30 years now! If the motor does go pop I've have a decent quality replacement in stock for 20 odd years. (Or I may just junk the saw now I have a Rapidor and proper Startrite vertical about the place. Alpine is rubbish now, was rubbish when new but it works well enough to be just about tolerable.)

Clive

Thread: Running small stationary steam engines
14/02/2013 14:03:45

Another one to look out for is the baby Hydrovane device made for Binks Bullows (?) as part of a portable paint spraying set-up. Curvy finned bottom bit, sort of sphere with bits chopped off at top and bottom shape, about a foot across with three legs barely long enough to keep it off the deck . Driven by an old style 1 hp or so single phase motor sat on top with the shaft vertical. Couple or three cubic ft per minute at 40 psi I think. I've heard noisier electric motors running on their own. Heavy for its size being, apparently, built to run for about half an hour shy of forever! Mine cost me £5 at a boot fair. Seller didn't have a clue what it was, neither did I but at the price .... E-Bay varies from near enough nowt to just plain silly. Also found with a Vincent Firefly(?) two stroke engine but that won't be quiet, even if it runs.

Clive

Thread: moving a mill
04/02/2013 19:01:43

Cheap castors won't hack it for a Bridgeport. Rule of thumb is that you have to start calculating at anything much over 100 lb. / 50 kg per castor. Things run a lot easier if you can keep within shouting distance of half the rated load. My heavy duty dolly has four castors with wheels about 2 or 3 inch diameter and 3 or 4 inches long rated at around 1,000 lb. each. Bridgeport and Smart & Brown 1024 lathe roll around the shop very nicely on that. Wide wheels instead of the usual skinny ones make a big difference. I have some jack-up castors with 8 inch diameter 1 and a bit inch wide wheels of similar, maybe greater, rating which don't roll anything like as well when similarly loaded.

If you have distance to go pneumatic tyre wheels roll best but note that E-Bay seller ratings for inexpensive units can be way optimistic. A set I got for a one time job were claimed to be 4 x the actual tyre rating! They should have gone back but supplier simply gave me a refund. Loaned out and used close to rating one wheel bent!

Clive

04/02/2013 17:15:08

Good points one and all. However if its a nice solid pallet and you have the headroom why not just leave it on the pallet, even if it means a few drinking vouchers to the delivery driver. If it comes out a bit tall, making a duck-board or operators step is a lot less scary than knife'n fork methods of moving it off the pallet without proper gear. Makes any future shifting a lot easier.

Remembering the first 3 rules of Bridgeport shifting 1) Its top heavy and tippy, 2) It's really tippy, 3) It's really, really tippy I'd advise some timber framing fixed under the table arranged to ride close to the ground. Use the knee adjuster to set the ground clearance to as much under an inch as is practical and lock the knee. Don't forget to provide feed screw clearance when fitting. That way if it does tilt or slide everything comes to rest before disaster giving you time to figure out what to do next. Pallet trucks are a lot less stable than you might think with a tall load. Especially if you try for too tight a turn. I've seen a Bridgeport take one over easy as winking. Very impressive bang!

For lifting mine if re-arranging the workshop I made special bars and brackets which locate in the bolt down holes using expanding anchor bolts. These bolt in turn to four scissors jacks ( ex SAAB) allowing me to inch it up enough to sit on slide bars, rollers or skates as need be. Lots of packing during the process so its never up more than about 3/8 each corner.

Clive

Edited By Clive Foster on 04/02/2013 17:17:45

Thread: Bench for SX3 milling machine
03/02/2013 22:25:56

Kitchen worktop is, in my view, a more suitable material than ply for making a raised plinth under a machine. Much less crushable, dimensionally more stable and pretty much impervious to oil. Affordable modern ply is pretty rubbish stuff anyway. The quality material is really too expensive for bench tops. The green waterproof chipboard underfloor material makes excellent bench tops (and workshop floors) being tough, pretty much oil proof and with a slightly rough surface that helps retard small components making a bid for freedom without being so rough as to stop you sliding heavier items. Check before buying tho' as my local supplies have both the green coloured version and a slightly less expensive natural colour version with a much looser surface which is dusty as heck and quite unsuitable.

Whilst you are at it put some thought into arranging a chip tray and suitable shields to stop chips getting everywhere. Reaching round the back with a brush etc gets old fast. Jason has a neat set-up but I'd be inclined to add some sheet shielding. Doesn't have to be permanent. Hinged L or similar shapes either self standing or on weighted bases work fine and take up little storage space when folded. Off-cuts of the plastic shower wall stuff hinged with duct tape do very nicely both for there and as covers for the unused parts of the mill table. Digging chips out of the Tee slots gets old too. The covers I use on my Bridgeport are 3 inch wide sections, 2 sets of 6 duct tape hinged together.

Clive

Thread: Bridgeport values/costs/servicing
31/01/2013 15:17:14

Darn. Should have picked up that TOS around the turn of the year then you could have had mine!

My 1976 Varispeed with 6F powerfeed and defunct Newall DRO cost around £660 (plus a days money to a friend for hauling'n installing help) back in 2007. Accidental purchase as I didn't really want a metric machine but won it with a minimum bid on E-Bay figuring that £300 or so under the going rate would compensate for wrong language. Dealer purchase. Basically sound with good screws and ways but filthy and priced to move 'cos it wasn't worth their while to clean. Turned out to have a siezed spindle. Left out in the rain by previous owner. Found there was still water in the head on stripping. So I had to go right through it, fixing a few other things on the way. Dealer got the parts for me at near enough cost price so I wasn't too unhappy. Bottom line is I have around £1,800 in it after fixing, fitting 3 axis glass scale DRO, pull wire quill travel sensor and Bjur spraymist box. Not counting tooling ( getting on for £1,000 maybe!) and proceeds from selling the 2 axis Newall Digipac 5 DRO that was on it. In car terms I guess condition is decent 50,000 - 70,000 miler if you see what I mean. Not perfect but does a good job and I know it inside out. Not too shabby a deal all in all, there is a Y-axis power feed to go on once I've tracked down the slector relay board circuits.

Forget the "Varispeed is crap" crap. As ever its all about condition, condition, condition. Step pulley versions have their own issues. Big difference is that a step pulley can be patched up but a varispeed needs to be fixed properly but when its done its done. I guess a varispeed lasts a couple of decades or so if not abused. The heavy motor keyway wear illustrated by John S in a previous post is not normal. Mine still had the original formed in place turquoise bushes on the varispeed disks. Well past their sell by date and seriously broken up with bits of bush and most of the keys gone AWOL. Some very minor filing got the keyways straight and a quick touch in the lathe bought the shaft true. Delrin bushes and keys made to fit, probably 10 thou oversize on the key, 10 thou under on the bushes and it will probably see me out. The original parts had sailed though a machine rebuild by InterCity Machine tools back in the day. Bridegport opinions are distorted because there are probably more of them about than all the other variants put together so absolute numbers of poor condition machines are greater even if the overall percentage is no different. Being common also makes developing a fix for wear related problems worth it so as the fix can be got its worth being fixed if you see what I mean. I've seen dealers take Bridgeports in worse condtion than Beavers which were subsequently scrapped. A Bridgeport can be shifted by knife'n fork methods and sild under an 8 ft ceiling easily enough. Bit different for a Beaver or TOS.

6F factory power feed used a high quality industrial DC motor and meaty metal gears. Vastly better than the Servo style aftermarkets. Mine was full to the gills with carbon dust but a good scrub, new brushes and replacement microswitches on the box sorted things for chump change.

Prices look to have hardened recently I guess my deal would come around £2,200 these days. But you should aim to start out better. If you can wait for the deal, finger in the wind says around £1,600 to go straight into service with a 2 axis DRO on board. (But you can get lucky. OK its a lathe but last year a sweet Hardinge clone with DRO went for £400 from just round the corner. I run a Smart & Brown 1024 VSL so of less than zero interest to me.)

Clive

Thread: Domestic bridgeport
26/01/2013 22:13:56

From the home shop / ME point of view there are two big wins when going for a Bridgeport as opposed to a smaller, hobby market machine.

Firstly the price - performance compromise in engineering is comfortably above anything we'd need to do. Industrial users expect what they buy to do what it says on the box. Hobby types have to persuade what they can afford to cope with what they want to do.

Secondly the space for setting up jobs. With smaller machines it can be a right faff getting room to fix, align and measure a job. On a Bridgeport just winding the handles will win enough access to set-up pretty much anything you can handle on your own. I had one of the big dovetail column bench-top mills with R8 spindle before and there is no comparison in ease of set-up. How you chaps with the smaller machines manage I shall never know.

Big disadvantage is that it gets much harder to turn down 12" to the foot "please fixit" jobs 'cos you don't have the easy "my machine is too small" excuse.

Major warning. The head is heavy and seriously unbalanced when rotated about the horizontal axis via the worm drive. That drive isn't exactly over-engineered so wear or abuse can soon erode the safety factor. I'd not attempt to rotate the head solo before inspecting the worm drive and worm wheel to verify that all is in good condition. Mine had a well worn wheel with one bolt missing and a sloppy key. If you do need to rotate it (eg when inverting for transport) get assistance to hold the head and a spanner on one of the lock bolts to snug up if it tries to escape. When rotating on your own do make sure the pull out stop pin is in place. I'd not go past the pin without a helper around, if you are on your own do rig up a safety strap. If pulling off the head fix a strong vertical post to the table, grab it with a collet and stabilise the head with suitable wood blocks or other devices. Now you can use the screw feeds to draw it off or align for re-fitting.

Clive

Thread: Plating solid lubricants on highly stressed parts
19/01/2013 12:44:06

Oerlikon Balzers do a wide range of vacuum applied coatings for high stress situations. Website is **LINK** for the UK division. Helpful even for the one off customer but not cheap. Around £400 to get all the innards of my Norton Commander gearbox done. The Triumph based 5 speeder being somewhat overloaded by 90 odd rotary horses and even Castrol R was only able to keep things spinning for 90,000 or so miles before gear damage started to appear. Post coating the gear change is much, much easier so I figure the claims for reduced friction are very valid.

Clive

Thread: Handwheel Driven Leadscrew
26/12/2012 22:50:38

I never found the reversed motion of a directly fitted lead-screw hand wheel any great problem. One tends to adapt quite easily. I'd agree with Jason that such handles are rarely used for turning. Once I got a graduated ring fitted mine was mostly used to help set up rods on a 6 position turret type bed stop. Very handy when a job had steps of various diameters. In my view a multi-position bedstop is an essential accessory.

A calibrated leadscrew handle is, of course, pretty much essential if you wish to get much use out of a vertical milling attachment.

Clive

Thread: Screw thread handbook
15/12/2012 15:47:49

Terryd

Decimals get misplaced or taken to excessive extremes whatever the system. Problem with metric is that its seamless nature and limited unit set make it very easy to follow a logical path from sensible to just plain silly. With imperial there are plenty of potential "hang on a sec" break points and different ways of setting up the problem making it easier to see when the line is being crossed. Inappropriate units is always a good indicator that someone has crossed the line or is trying to pull the wool.

Good point about engineering being in decimals but this not so much intrinsic as due to the fact that most of the time clearances or fits are what matters. If you need a ten thou clearance on diameter between shaft and hole then obviously you must work in thous (decimals) as this is an appropriate unit for clearance but for fundamental engineering it (usually) matters not a jot whether the shaft is 0.500" and the hole 0.510" or the shaft 0.490" and the hole 0.500". Fact is no one would be surprised if the whole kit and caboodle would engineer to work just fine with a 3/8 or 5/8 shaft. Of course if you see a call out of 0.5118" you know there is a metric conversion from 13 mm going on but when you see things like 0.5256" its fairly obvious that its time to check the maths and drawings. 13.35 mm is just as potentially silly but it doesn't stand out as much.

My wage slavery was as a scientist / R&D engineer and I saw plenty of occasions when people (including me) went seriously awry due to following the numbers and loosing track of what they meant. Once had to teach half the attendees of one meeting imperial and fractions from scratch to blast them out of a rut of vastly excessive performance expectation due to chasing the metric numbers. (Self protection as I was gonna have to build something to demonstrate what was decided upon! ± 10 nm range-finding at 10 km, get real guys!!).

Clive

15/12/2012 11:39:25

Agreed John comprehensive is indeed probably an impossible dream. Especially if you consider the OEM specials used by, for example, instrument makers (Hi Mr Starrett), carburettor companies et al. So we are stuck with multiple sources. Short series listings where a few threads have been pretty much agreed on by industry for specific applications can be a great help as knowing what its for cuts through the "which form is it / nearly the same metric or imperial" confusion which can be a major pain. Most specials seem to be itsy bitsy tiny or / and very short which doesn't play well with 58 year old eyes.

I do wonder what some of the standards committees were smoking and drinking at decision time tho'. BA threads no 20 and below vary in diameter by around a couple or three thou and pitch increments are around 3 to 5 tenths of a thou! Leaving aside the practical difficulty of separating t'other from which when identifying a replacement and whether or not producing threading tooling to the necessary precision was actually industrially realistic at the time the standards were defined you have to ask just what difference such small variations make in engineering terms. Probably yet another demonstration of the ease with which complete disconnection from reality occurs when using the all too often obnoxious metric system. So easy to drop another decimal place without thinking it through. Seamless progression through many orders of magnitude can be great when doing science but, cumbersome though they are, fractions have something going for them when interpreting engineering.

Clive

15/12/2012 00:01:28

Sorry John Guide to World Screw Threads may be the ultimate book but its still not comprehensive, I've hit a few that weren't in there. Newnes Engineers Manual and Caxtons Engineering Workshop Data fill in some of the gaps. Especially with handy dandy listings of some of the oddball special purpose short series, plating allowances, washer sizes et al too although horribly out of date by now at least they give you some idea. (Nice to discover that that box of high quality but way out of spec bolts I found were actually made to size for thick chrome plate!)

Not a handbook but really helpful when a "Can you fix this?" job comes out all obscure is the listing of of a wide range of threads in ascending size order originally due to Andy Pugh and extended / reformatted by other workers. The original is at :- **LINK** Two other sources are **LINK** and **LINK** . The last is probably nicest formatted version.  I now use an Excel format version but I don't know where that came from.

Clive

Edited By Clive Foster on 15/12/2012 00:04:21

Thread: Unusual thread
14/12/2012 23:31:41

16-18 ASME is 18 tpi 0.268" diameter so probably close enuf. ASME is (I think) American Society of Motor Engineers and are basically to American National standard form but covering a fair number of oddball sizes and pitches for automotive applications. Usually finer than AN versions, altho' not in this case.

So far as I'm aware the systems heyday was in the First World War and early post war period slowly petering out between the wars and in the post Second World War period save for a few examples which were kept in step with AN / UN thread size, form and specification evolution.

Newnes Engineers manual is the only UK book I'm aware of with a full ASME thread listing. Size designations are strange by modern standards as the number-thread system is used extending up to 30 which is 0.45" diameter. ANF / ANC number sizes are a subset of the ASME list which usually offers several choices of pitch for each size rather than the familiar coarse / fine pair. No 4 and No 8 have four choices each! Surprisingly not in Machinery's Handbook or World Screw Threads Guide.

Clive

Thread: Swarf vaccum cleaner
03/12/2012 22:20:25

And one more thing!

Coopers of Stortford are doing two varieties of ash vacs mail order. £40 for a self contained one with its own motor and £15 for a can, hose and filter unit which gets its suction via your own vacuum cleaner. Second option might be well worth considering if you like to separate out your swarf where two or three cans could be handy. As Terryd says its not that difficult to make your own auxiliary collector can but there is the usual time, aggravation, cost balance to consider especially if you haven't got everything to hand.

I brush'n shovel to get most of the swarf out an use one of the older metal bodied "Henry-like" Numatics to get the bits I missed. I do separate out the brushed'n shoveled stuff, yellow metals especially, but the vacuumed up stuff ends up in one bag.

Clive

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