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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: Screw thread handbook
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of some of the oddball special purpose short series, plating allowances, washer sizes et al too although horribly out of date by now at least they give you some idea.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

Thread: Older Sievert Gas Torch Advice Needed
22/11/2012 15:10:53

Recently picked up a brace of older style Sievert gas torches with several burners in decent used condition and looking for advice on what I have, set-up, care and cleaning. A quick check following visual inspection shows no leaks, although the connecting hose is clearly towards the end of its life and will be replaced, and the burners do light up OK..

1) Nothing looks abused or overly used, the meshes at the screw end of the burners are clean but the flat sealing washers are grooved and look a somewhat old. Presumably replacing the seals would be advisable. If so where can I get them and is there anything else which should be done or changed?

2) Burner type numbers are old style 4 digits whilst current ones have 6. Several have numbers common to the current range and look the same:- 2941, 3537, 3939, 3941. Can I assume they are, for practical purposes, to the same specifications as the current types.

3) Three of the burners don't appear to have direct number read across to modern numbers:-

2940 which has a thick tube about 3/4 inch O-D and 1 1/4 inches long with a swaged in end fixed to the burner proper by a single side screw

2950 which looks to be a cyclone burner being a 5 inch or so long curved tube with air inlet at the base and burner at the top.

46573 which as a flattened end fishtil style tube held ahead of the burner by a single screw and a shroud over the air inlet holes at the base of the tube close to the torch fitting.

4) There are no numbers of the torches. The smaller one is a has a hard, glossy handle (bakelite?) with Sievert Original moulded in. Original in very cursive script. Control knob is brass. The larger one has a more modern style black plastic handle of matt appearance and plastic control knob with sheet aluminium insert for the on-off logo. Are these till safe to use if in apparently good condition after careful visual inspection? Are there any seals et al which should be changed?

5) The gas connector screws direct into the bottle with a rotatable connector assembly identified by a transfer carrying the number 3085 and instructions in Swedish (presumably) and English. English is "Push to Re-Open" so I assume this is a line rupture safety valve. Can I assume this is still fully functional?

6) There is no regulator with the set I have so is it OK to use direct off the bottle or should I obtain a regulator unit (with line rupture valve?) before putting into service? It appears that 2 bar is an appropriate pressure for all the burners that have modern equivalents. I've always felt that a system with a regulator is safer and more predictable in performance.

Thanks for any assistance.

Clive

Thread: Quorn or Vertex cutter grinder ?
05/11/2012 15:01:19

Chris

If you only need to do twist drills and the ends of end-mills and slot drills both are probably overkill. I believe the Vertex device you mention is a variant on the Deckel design and thus primarily laid out for engraving cutters although it does have lathe tool, drill and end-mill sharpening capability with the correct accessories. The Quorn is a do-almost-anything-that-can-be-mounted device designed to be within the construction capabilities of the skilled home worker. As with all versatile devices setting up and manipulation procedures need to be mastered before reliable results can be got. This can prove complex and, probably, regular practice is needed to keep your skills sharp. I suspect most Quorn kits are completed more as an apprentice piece to demonstrate that the builder is now a properly skilled worker than for a real need.

For more basic requirements the simple swing-across-a-wheel twist drill sharpeners, e.g. Picador et al, give very acceptable results once you have got your head around coping with the inevitable geometrical infelicities. Doesn't help that there are two distinct breeds with differing set-ups. Especially when some of the low end imports come with the wrong instructions! Things go much better using a narrow cup wheel rather than the side of a conventional wheel. The Atlas style which works off the face of the wheel is far superior, but was rather more expensive when on the market, and essentially never made it out of America. Despite being 'orribly plastic the one in the Plasplugs set works pretty well too. Martek, Drill-Doctor and the various poke-it-in-a-hole-at-an-angle-to-the-wheel types are notorious for some good / some bad results with no apparent rhyme or reason.

For sharpening end-mills devices working on the same principles as the Stevenson's ER 32 Sharpening Fixture sold by ArcEuroTrade http://www.arceurotrade.co.uk/Catalogue/Collets/ER-Collet-Fixtures should be adequate for most home users. That particular one requires a surface grinder but there have been various home user friendly designs published which use a standard grinder. The "Cannon" one published in either ME or MEW around 2000 (?) is probably the simplest and looked as if it should work.

If you fancy building a versatile device the Brooks (almost a Quorn Lite) design published way back in the early days of MEW looks to be a decent balance between function and build simplicity.

Regrettably the home worker is ill served by sharpening devices. Typically the choice is between too complex / too expensive / or too simple and needs too much practice. I feel that something combining TipLap style operation at a few fixed angles for lathe tools with Stevenson's style operation for 4 facet drill and end-mill sharpening would be more appropriate in function and cost. Interlocking finger Vee blocks are an entirely adequate alternative to collets for holding round shanks. Proper attention needs to be paid to repeatable tool positioning and projection via screws and stops. Setting to scales or card templates is not acceptable, nor is rotating the tool to the next flute, despite the prevalence of such methods in existing practice.

Clive

Thread: Design a covering mechanism
02/11/2012 23:32:55

On further consideration I'm no longer sure that the length wise roller blind style sheeting concept needs a bar at the free end. Given sufficient lift via the telescopic arms to cope with droop a cable should do just as well. Its not as if the load to be sheeted is anything like as high as curtain side or box trailer set-up so the lift is probably within reason.

With a cable defining the free end its probably workable to have fixed side to side ropes or webbing passing through loops on the surface of the sheet. These could be tensioned up over the load by some suitable inbuilt device like the common ratchet strap tensioner or simply exploiting the lorry drivers hitch to use up the slack. Not that I know owt about that sort of thing having completely failed to master the lorry drivers hitch despite being shown a dozen or more times!

Clive

02/11/2012 22:33:16

Putting the side to side suggestion from Clive H together with the front to back sheeting arrangements on tipper lorries how about having what amounts to a giant roller blind lying along and under one side of the trailer. Two power driven telescopic arms, one at each end of the trailer, pivoted on its centre line with a bar between to which the free end of the "blind" is attached could lift it over the load and down onto the other side whence the bar could be attached to the trailer. Rotating the roller would give basic tension supplemented by suitable fixed lashings to draw in the ends and pull down loose parts.

Obvious problems are needing a long, slender and therefore bendy bar to hold the free end of the sheet and arranging the lashings. Clearly some sort of loop or eye system would be needed to keep the lashings in place during deployment as clambering up to retrieve them would defeat the object. Likely to be heavy too.

Unlike Jeff I see nothing wrong with seeking information in a hobby forum. Its a good way of getting out of the box thoughts and ideas. The big gap between idea and device would naturally be filled by proper engineering. If there were an "in the box" concept floating around it would probably already be a commercial product.

Clive

Thread: Bridgeport Series 1 Varidisc Head Bushes/Bearings
27/09/2012 21:57:34

Paul

No problem to send the PDF drawing. Where do I send it?

Do remember to check it against your machine before following as its amended but untested. I corrected the errors in the original reverse engineered drawing to match what actually fitted but I haven't made another set to check. Making is a horrible job due to the thin wall and uncertainty as to how much the delrin will spring when you make them. Can't make turquoise style ones thick and bore out after fitting because they need to be very flexi to get in.

Pictures of the making process too if you want. Was going to write it up for MEW but first draft was so bad .....

Dunno what grade of loctite I used to stick them in with.  Probably one of the high strength ones (green?).

Clive

Edited By Clive Foster on 27/09/2012 22:00:59

27/09/2012 15:31:13

Paul

Dimensions vary according to motor power and year the head was made. I made a new set to replace the turquoise bushes in my mid 1970's head with 1.5 HP motor. If yours is same power and has same colour bushes I can send you a PDF of the drawings. Note that the turquoise bushes appear to have been moulded in place then bored as there is a retention ridge halfway along fitting into a mating recess in the pulley which makes life complicated when going for an exact fit. Mine fit and work fine using loctite to retain them but I suspect the ridge is a little undersize in its groove. Some guessing involved in reverse engineering as mine came out is several parts and I never did find them all.

Later ones than mine have simple plain bushes which are easily reverse engineered. These are the ones the US kits are for. Sorry I don't know what year the change occurred, i think it likely that you have plain bushes.

Clive

Thread: Tilting table.
23/09/2012 22:16:19

Tapping a grid of holes is tedious. Much easier to bolt on one of the breadboard systems used in optics lab s which come complete with a suitable grid. I've used the Thor Labs ones **LINK** with every satisfaction. £100 to £150 range for you I guess. I figured the cost was worth it compared to tapping all those holes. The anodised ally surface is very tough.

I'd put Tee slots in the table itself after considerable thought as to best size and spacing given what you intend to bolt on.

Clive

Thread: Replacement feed chart needed.
21/09/2012 21:58:24

Dave

Inkjet printer output laminated into those plastic sheet thingies makes a very effective label or chart. Plenty durable enough to fix to the machine.

Certainly good enough to be an improved replacement for the standard effort which, in comparison with the brass embossed (or even cast) and paint versions of yesteryear are pretty manky. Injet lets you use colour which ought to be a great help is seeing what's what. The laminators sold for, approximately, the modern equivalent of thruppence three farthing by Lidl, Aldi, Maplin et al are very effective and more than up for this kind of job.

Clive

Thread: cutting metric fine thread
16/09/2012 23:53:26

Garry

Thread depth for a given pitch is constant regardless of the diameter. So simply look up 4.5 x 0.75 mm in the Zeus book and read off the depth there. 0.4601.

Of course the actual cut depth depends on whether the insert is full or partial profile. Full profile just go to the book depth, partial needs to go a little deeper depending on the thread range covered. Partial profile specifications should be in the insert data book or you can figure it out from scratch starting with the thread range. A drawing helps.

Sometimes you can use a normal threading set-up gauge, usually only the smallest notch will go. Insert and holder data book should help you with alignment issues. Many are made so the thread form on the insert is parallel to the shank of the holder so its easy to align the holder. Aligning the holder is normal practice with the Johannson / SKF chasers I prefer. Unfortunately they are getting very hard to find.

Clive

Thread: Dial Gauge resolution?
31/08/2012 21:42:29

Neil

I guess its what you are used to. I've never considered a plunger that easy to set-up, not least because of the extra weight relative to the small Verdict. For me longest job is sweeping off the ferrous swarf so the mag base doesn't do a porcupine imitation.

Tip:- wrap the mag base in cling film or pop in a small plastic bag before approaching the machine so that any swarf that does get attracted can easily be peeled away with the bag / cling film before putting things away.

If you have a chuck guard of the type which pivots up on a rod sticking out pretty much parallel to but above and behind the bed its well worth making an adapter to fit the adjustable arm out of the mag base set to this rod. Maybe via an intermediate arm. Can make life very easy when the job or general stuff gets in the way of plonking the mag base on the cross or top slide. Not a universal solution because you don't have the fine, accurate, screw driven positioning capability you have when fitting to a slide but there are times when it makes life far easier.

Don't forget the short slide on a spigot type carriers which let you mount up a lever type in the tail stock chuck with a useful amount of slide to side adjustment. Mine gives a couple of inches I think. When you need it you need it, Often found for chump change on Evil-Bay with an "I dunno what this is but someone does" description.

Clive

(12 gauges at the last count, I think, not counting the Heidenhains)

Thread: Tap Chuck ?
31/08/2012 20:18:46

I have what looks to be the same device as that linked to on Amazon in both sizes. Bought a goodly few years back the innards of the larger one failed in fairly short order. Investigation revealed a less than stellar detail design and execution inside the attractive case. As I recall nothing that couldn't be rectified with patience and ingenuity but, in 20 odd years I've not been able to summon up the enthusiasm to either fix or throw! Not exceptionally concentric as I recall matters.

Probably the Sealey set lower down are better but I've got 2 or 3 different breeds of those Vee jaw or collapsing square type tap wrenches and none are truly concentric. Or for that matter terribly firm in the grip. Starting a tap square needs even more than the usual concentration. Certainly no good for power drive. I've no idea whether the relatively poor performance is concept limited or simply a result of compromise to meet the marketing constraints of cost that the customer will pay against performance he can live with.

The common battery drill works well up to 5 or 6 mm given regular reversals, with a suitable torque limit set on smaller sizes, before chuck slip becomes endemic. I've often wondered if a chuck could be reworked to include a square gripper drive behind for the larger taps just like my proper heads. May be a nice project to extract the torque limiting innards etc. for an inexpensive DIY tapping head.

Clive

31/08/2012 18:36:24

The device linked to by pcb1962 is essentially similar to those fitted to drive the square on my Archer and Pollard tapping heads. I imagine that, like those there is a certain amount of float to let the device auto centre.

Clive

Thread: Dial Gauge resolution?
31/08/2012 18:27:16

Geo. H.Thomas says " For setting up purposes I regard the plunger type indicator as little short of an abomination". He is kinder than I.

For setting concentricity of rotation the lever type Dial Indicator is the proper device to use. Ideally with the direction of surface movement parallel to the lever. Unfortunately only possible on outside surfaces.

The proper home of the usual type of Dial Test Indicator with its plunger poking out radially sideways is on some sort of solid test stand with a component carrier beneath indicating deviations of a pile of parts from the nominal size, hopefully all within tolerance. After using slips to calibrate the relevant range of course. It also suits similar applications where the movement is inherently parallel to the plunger. The geometrical and mechanical infelicities involved in scraping a rotating surface across a tiddly ball point don't bear thinking about. Hopeless in bores too. If you use a 4 way or similar shim to centre tool post and fit an elephants foot it would be ideal for measuring the tool tip height over base off the machine so you can simply select the shims needed.

If you really must have a dial for set-up then the short travel back plunger instrument is the one to use. I have a full Starrett "Last Word" kit based around this sort of device which includes a pivoted arm especially for reaching down into bores.

Although I have a good selection of all varieties of indicators, including a triplet of Heidenhain moire fringe based probes, the shop workhorse is a basic small dial ± 15 thou Verdict. I purchased the Verdict at the first Model Engineer Exhibition I visited when a special offer price proved just within reach if I ignored trivialities like buying lunch for the rest of the month! Frankly I could probably still get by with it alone but the other toys make life so much easier.

The common terminology for these devices always seems odd to me. I was taught that the lever type was called a Dial Indicator because the dial indicates deviations from concentricity and calibration beyond a basic functional check is not needed. The plunger type was said to be called a Dial Test Indicator because its proper use is to test a deviation from standard having previously been calibrated in situ to relate the dial indications to the job. The plunger type also finds its way into various other instruments (such as bore gauges) and, so I was told, can be called Dial Gauges in such applications with the proviso that the calibration marks may not be assumed congruent with the measurement made by the instrument so prior calibration is essential. Common use often seems to be opposite but even textbooks can't agree.

Clive

Thread: Tap Chuck ?
31/08/2012 17:21:37

Power tapping by holding and driving only by the square is can unsatisfactory due to alignment issues. There are good reasons why the professional devices, like my Archer and Pollard ones, include a three jaw to grip the shank for alignment. Interestingly the very simplest form of three jaw, as used on hand driven drills, is deemed sufficient. Presumably as there is no requirement to drive so only light jaw pressure is needed.

For geometrical reasons a self centring square is inherently unreliable at holding to close limits, especially with small components. Also, as has been previously mentioned, tap makers do not take special precautions to keep the square truly concentric to the shank and thread form. The way things are done pretty much ensures that the square will be close to concentric but how close is a bit of a lottery. The point is concentric. Examination of the blend from point cone to square gives a reasonable idea of how concentric the square really is.

Clive

Thread: motor wiring
29/08/2012 22:32:31

No capacitors needed with that motor, it has a simple start winding. Lower starting and run-up torque than the capacitor start versions but I can't see that mattering on a lathe where you are only spinning up the spindle, chuck etc not trying to drive up against a load.

The NVR Norman suggests is effective and good value for money. Easy to wire as well. Not as durable as a proper industrial rated contactor but I've used similar budget range devices for over a decade when fixing things for other people and have yet to have one come back.

If you decide to use your switches and buy a contactor, any of the lower end industrial devices from RS components et al will be just fine. But do buy a DIN rail mount and a short section of rail. Fitting is sooo much easier compared to the usual "screws carefully placed so you can't quite get on them" set-ups.

Like Norman I'd not want to run in reverse with a screw-on chuck but if you do decide to use a contactor and the lockable forward / reverse switch its best to get the official Brook connections. I have a PDF of the Brook Gryphon sheet covering the full small motor range somewhere if you want it.

Clive

Thread: Setting angles
27/08/2012 11:45:06

I set a true running bar up in the machine and measure off that. A taper fitting test bar is ideal although I usually just put a known straight rod up in a collet.

Precise adjustment is hardest thing using the usual push, tap, curse method. Best to make some sort of opposed push screw thingy to fix on the cross slide and give positive, controlled, movement both ways. Geo. H. Thomas recommended 2 BA screws for pusher duties. That or 10-32 UNF seem a good compromise between stout enough to push and fine threaded enough for accuracy. 4 mm is nearly double the pitch and a bit too coarse.

Its advisable to have a good scrub up and lubricate under the topslide before attempting precise setting. Swarf, bits and general grunge do tend to work in there and the shop gremlins will take great pleasure in nudging the contamination into just the right place to ensure that things shift a bit when you tighten down after getting the setting just so. Push from the side locking systems, such as the circular wedge and angled pusher used by Boxford, Southbend et al suffer more in this respect than the simple through bolt or Tee nut in slot variety.

Clive

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