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: SIP co2 disposable bottles|
When you sort out whats what properly best prices for 600 g ones seem to be around £20 - £21 and 390g around £13 - £14 (ish). Gas price is pretty much same at £ 3.50 (ish) per 100 g so it doesn't seem to matter much which you buy. That said you can pay nearly £20 for a 390 g one if you don't watch out.
Sealey do a 1 Kg re-fillable bottle. Retails around £10 to £15 empty and £80 - £90 odd full. Yikes thats over £7 for 100 g but re-fills (exhange) from local agents are said to be much less costly so "the investment is soon re-couped". Still a rip off deal to get a full one tho'. I have one and think re-fill price is now around £20 which is a bit better than disposables. 30 mile round trip either way so I've pretty much given up on MIG having a high end inverter stick welder that can go nearly as thin.
|Thread: Knurling question|
The pressure of the knurls extrudes material up from the original plain diameter. The material has to come from somewhere so the knurling wheel points sink below the original plain surface. Effectively the knurl pattern comes into balance with some above and some below the original surface. The process inherently has some leeway as to exactly what diameter the balance occurs at so the starting diameter doesn't have to be exact. In practice its rare to take a knurl right to sharp points so errors can be hidden in slightly sharper or slightly blunter points.
In practice for medium knurls on typical sizes of material, say half to one inch diameter, one more or one less knurl point translates to around 10 to 20 thou variation in stock diameter so extrusion variation can take up most errors. As its a symmetrical process which can go either up or down the actual range will be ±5 to ±10. If the workpiece is small or the knurl coarse you may get thin slivers of metal cut off the sides of the knurl points when the error is a bit excessive.
I rarely worry about stock diameter unless below 0.375". Just have at it until things look right works fine.
|Thread: MJ Morse taper|
Neil's supposition follows the standard explanation that the slight variation in the taper angle for different sizes of Morse Taper is due to errors in the master gauges. Plausible but I don't buy it. I think it deliberate policy.
Even in 1864, when the Morse Taper was invented, technology was well up to the task of producing accurately tapered master gauges. Albeit somewhat laboriously. Its setting the gauge plane that is difficult without accurate length measurement and adjustable standards. From a production viewpoint multiple tapers are a pain as needing separate masters and setting gear for each size. One size fits all, Jarno style, needs only one master calibration reference and one set up device.
The variations seem too large to be simple errors and the actual tapers per foot are extremely inconvenient dimensions. This suggests that the variation is deliberate. A plausible reason is that it would force firms wishing to make equipment to use Morse drills to buy gauging and maybe production equipment from Morse with obvious financial benefits. Single sourcing gauging equipment would also help maintain quality standards. Taper and similar self locking drill / tool holding systems had been introduced before and failed to become widely adopted due to machine to machine variations giving inconsistent performance. No proper drawing standards, or even drawings, in those days.
Another plausible reason for deliberate taper variation is to ensure that the system only works with the male taper fully inserted into the female one. Partial insertion of a too large male taper into a too small socket will not drive and is obviously wrong. Same taper throughout risked proliferation of odd sized and partial length variations. Probably accompanied by workers resorting to the BFH when things failed to behave. Still in the era of folk weighting down boiler safety valves!
Edited By Clive Foster on 20/05/2017 18:46:01
|Thread: Bridgeport (A&S) Manual 42" Power feed conversion?|
The Align and similar kits need the extension adapter shaft on a Bridgeport previously fitted with an electronic (6F, 8F) power feed. Standard screw is too short because it mates with the shaft inside the gearbox, dials et al are all carried on the gearbox so its a single unit fit. Agreed the official ones are stupid price for what they are but they will be the right size and everything will fit.
Looked into doing the Align replacement way back when it looked as if the 6F unit on the "new to me" Bridgeport was pemanently dead. DIY extension looked a useful saving but, after roughly drawing up, it looked too much faff to make. Not that complicated if you have an accurate drawing but everything has to be right. I figured measuring properly was going to be too hard with the gear I had then.
Hafta ask why you need to change the unit. Mine just needed new microswitches, a broken wire replaced, new motor brushes and loads of carbon cleaned out of the motor. Ten years down the line its still good. I understand that commercial repair of an Erskine power feed board is around £150. DIY for a reasonably skilled electronics person is practical but the pulse transformer specifications don't seem to be available so if thats gone you are stuck. Or a standard 90 V DC motor drive can be found for a similar price.
|Thread: Help from any Kennedy Hexacut Power Hacksaw owners out there?|
Chris / Michael
The automotive ribbed "serpentine" belts actually work better rib side down on flat belt pulleys rather than inverted. Ribs squidge a bit so there is some length tolerance.
The one we had at work used a Stephens Miraclo (spelling!) glass fibre backed leather belt which worked a treat for the 20 years i knew of it! Might have shut down by now tho'. Some of the plastic types may be OK but I know the yellow one supplied for my Clarkson grinder would be too stretchy.
Edited By Clive Foster on 15/05/2017 16:30:21
|Thread: Lumiweld alloy solder|
Was told that Lumiweld doesn't stick to stainless steel. Looks like it doesn't stick to steel either :- **LINK** .
With a thread I'd be happier if there were some sort of clean, low adhesion plating or coating on it to help stop the thread pulling out. Sooting really doesn't seem the thing when its universally agreed that the secrets to success is absolute cleanliness and scratching though the aluminium oxide layer so the Lumiweld can do its melting point reduction magic. Way back i recall seeing a steel bolt or shaft put into a solution of something in water and pulled out a few hours later with a thin, fairly easily scrubbed off, layer of copper on it. If memory is correct might be worth looking into.
Dunno how well the Lumiweld would follow the threads in the stud tho'. I'm considerably less than expert but my blobby bits didn't come out with a very good replica of the surfaces they fell on when examined after scraping off.
|Thread: 2 odd items?|
Another vote for loo or vehicle cab. Pretty sure an older aunt and uncle hung one in their outside loo during the winter but thats going back around 55 years to primary school days so both memory and appreciation of what I was seeing may be less than reliable.
The under car version dad had (maybe I still have) was much lower and larger diameter. Maybe 4 or 5 inches high and approaching a foot diameter.
|Thread: Canadian needs help with a Britannia|
Looks to be a later version of the second one illustrated on the Britannia home page at lathes.co.uk and in first set of photographs. No obvious evidence of significant modification.
Typically machines of that era used fairly standard change gear set-ups. I have listings for some leadscrew pitches / TPI. Easy enough to copy and E-mail if one matches yours.
The gear peeping out from under the end of the cross slide suggests it has power cross feed but where it picks the drive up from and how it's engaged is somewhat unclear. At a guess one or the other of the two round knob things" pulls out to engage the feed. Southbend et al used a keyway in the leadscrew but I suppose some form of gear engaging in the leadscrew rather after the fashion of a thread dial indicator is possible.
Irregularities at the back of the hole may well help stop rotation by engaging in the mushroomed bit. But an irregular hole, whether in bore or on surface, will interfere with the collapsing and grip behaviour in a manner reducing the frictional hold. If you gain more from grabbing the irregularities than you loose from imperfect collapse then the overall effect would be to increase maximum torque before rotation. Conversely if you loose more by imperfect collapse, clearly maximum frictional grip requires the collapse to be perfectly symmetrical, than you gain from physically engaging in irregularities the maximum torque will be lower. Completely unpredictable in practice which is why careless drillers get such variable results.
In the real world serrated and hex bodied versions use engineered irregularities to improve torque capability. Usually such need more ooph than a simple manual plier or, for larger ones, lazy tongs installer can apply. Pneumatic installers seem to be the professional weapon of choice. Usually with controls to set the installation force to what the insert maker decrees.
Seems to me that the screw driven opposed pair of sliding wedges style of installer would be effective for types that need higher forces. Pretty easy to make something that would work off a back of the envelope sketch. But it would be nice to have some idea of optimum wedge angle and how bolt torque translates into installation pull. If splashing out on good ones it seems sensible to fit them properly. After all higher end versions have rated torque capabilities significantly exceeding the shear level of ordinary bolts.
Huge variety of the things. Work really, really well if you choose the right one for the job and install it exactly as per specifications. Which, realistically, Home Shop types aren't going to be able to do. If nothing else most of the high performance ones can't be got in small numbers although some of the automotive ones can be found as manufacturers spare parts. At a couple of £ each if the ones I got for my P38 Range Rover are typical.
Plier tool kits tend to come with general purpose, light duty, types intended primarily for panel fixing and holding up fairly lightweight things with multiple fixings. Don't have to be that fanatical about the lightweight side of things, big panels can come out heavy, but I'd be chary about anything over one hand lift weight. The multiple fixing thing is essential tho'. You really don't want the rivnut twisting during installation or when whatever its holding get knocked as any shift seriously reduces its torque resistance and will almost certainly make the fixing irremovable without very serious attention. Important not to over torque the screw or bolt. Some determined nooging around the internet should unearth figures for ones similar to what you have. Way back I was told, possibly by a visiting rep from RS Component (remember them), that something around half maximum torque for that size brass fitting was an appropriate maximum for those they sold. Which, for small screws, isn't much.
You must have a clean hole neatly de-burred on the back. Ideally with a nice sharp corner. In my experience the de-burring and sharp corner bit is where folk get into trouble with blind holes. All seems very variable. Sometimes Mr "I'm in a hurry so its gotta do" can get away with absolute murder and sometimes Miss "usually very careful" gets bitten after what should to have been a quite adequate installation. Really don't want them to turn during installation which is why the bolt and nut trick can drop you right in the kitty litter as can trying to improve the grip by tweaking up the bolt a bit over tight. The grip comes from the collapsing part both mushrooming over the back of the hole and simultaneously expanding to wedge inside the hole. Indeed some types, intended for thicker materials, just wedge themselves in the hole without the mushroom over the back. The wedge in the hole effect is why you need to use the appropriate fastener for the panel thickness. Curious Clive tried a few wrong 'uns and was a bit surprised at how much difference it made.
I think it best to lubricate the fastener with coppaslip or similar. Other folk swear by sealing the threads with the lowest strength loctite. Been known to anoint the hole with supaglue for a bit of extra torque resistance, most likely the feel good factor vastly outweighed any real world gain.
Bottom line is that rivnuts are very forgiving if you don't push the envelope too far too often but that forgiveness means its easy to get in the habit of expecting too much too often. Bit like over torquing bolts. Usually you can go beyond the official limit but eventually you get bitten.
|Thread: Screwcutting Crashes -|
There are a number of less costly ways than a QC tool post of getting round this problem. Here are three examples:-
1) Revise the tool grind so that the tool post can be set square to the top slide. Essentially you move the tool shape round by 30° instead of the tool post. Disadvantage is that the tool post is no longer parallel to the lathe axis so the overhanging corner could come into contact with the job on longer threads.
2) Make an offset carrier for the threading tool. Basically a slotted block with a bar on the back to clamp in the tool post slot. Similar to the common carrier for insert parting tool blades.
3) Make a larger tool post with its base reaching out to the corner. This is the way I'd go having used a bunch of 4 way posts as a poor boys QC substitute in SouthBend driving days. Built up construction from two plates and a centre block glued'n screwed together is quite satisfactory so relatively simple to do using stock materials. Ideally you need something faster than the usual nut holding everything down. Especially if you find, as I did, that a fully loaded four way tends to have unacceptable vampire, or even carnivorous, inclinations so a two slot block is much safer.
There are several other perfectly acceptable methods but those are enough for a forum post. I started to do an article for Neil on various less costly and easily made methods of adding most of the virtues of a QC system to a basic top slide. Nearly all the concepts covered would have solved your problem. Unfortunately it got a bit out of hand. Maybe I'll finish it and do as serious edit this winter!
|Thread: Another grinding question.|
Not a myth that scraping produces a better bearing surface on cast iron than grinding. Low speed tribology is a complex subject but the oil retention effects of multiple scraping depressions are real. its been demonstrated with stick-slip measurement of the power needed to shift lathe and mill size slides from stationary up to normal travers speeds. Generally considered necessary that ground beds should be hardened to get a satisfactory life which further indicates lubrication issues. Interestingly many of the last generation manual "super-lathes" had hard tool steel inserts for the main bed guideways with scraped cast iron saddles running on them. Theory was the hard steel guides could be replaced when worn. In practice it was exceedingly rare for the machine to wear sufficiently for replacement to be needed. Allegedly adding matching hard steel insets to the saddles didn't work out too well and was never done.
Scraping V surface grinding really boils down to how good is good enough and how good a surface grinder do you have access to. Typically basic surfacing grinding flatness tolerances are in the region of ± 1 or 2 thou per foot. Which can be improved on with extra effort but it starts getting expensive fast once you go beyond a few simple passes. Considerable overlap with milling capabilities and its quite practical to produce milled surfaces as flat as basic ground ones. For relatively unsophisticated processes the big difference between milling and grinding is in surface finish.
This link gives a nice short overview of practical tolerances and surface finish for various processes :- **LINK** . Downloads a short pdf file with figures & text.
Scraping accuracy pretty much depends on how patient you are and how good your master(s) are. Allegedly any patient person willing to learn the technique can get to 50 millions of an inch per foot (0.000050, half a a tenth of a thou). If you really want to work at it an order of magnitude better is quite possible.
|Thread: What do you think of these lathes|
If you are able to spend around £4,000 to £7,000 on a machine from a reputable dealer limited knowledge is no handicap. Endless variations in that range over cosmetic condition, equipment with it, DRO or not etc, etc but you will be able to pick up a machine still tight and pleasant to use with more than enough accurate life left to suit the most industrious home workshop guy. Need to discuss your needs very carefully with the dealer and not get too ambitious in what you get for your money. Always better to pay a bit more for something nice than chance your arm on the scruffy but well equipped one in the corner with twenty years of oil encrustation, dark brown chucks and so on. Home and Workshop Machinery have a couple right now which are a pretty good illustration of about how far down in cosmetics and price its safe for someone in your position to go with DRO equipped machinery. Unless it's pretty modern a DRO isn't worth the mark up. Better things to do with the money when a satisfactory brand new system can be got for around £500.
When it comes to haggling probably better to negotiate on delivery or extra equipment rather than beat down the price. Big lump so best let the pros handle moving it and they can come expensive for a single move one off job. Best to get face-plate, steadies, 3 and 4 jaw chucks with the machine. And more QC tool post holders if there is only a basic set of 4 with the machine, * is minimum complement in my view. Skimp on the equipment list at purchase time and you could easily spend £1,000 to bring it up to the mark later.
Its the folk digging around the basement £2,000 or less machines who really need plenty of knowledge. £2,000 to maybe £4,500 is where the screaming deals and totally overpriced junk live. Almost invariably filthy and left exactly as it stopped at shift end 3 months or more back. No place for the inexperienced or unescorted.
Like the one you linked to. Looks smart, realistic price for a very good one from a known to be reliable supplier.
Compare to this one **LINK**. which would need a really serious crawl over to be sure it was up to the mark. Even then cosmetics would make me wonder. Somewhat overpriced methinks.
An Anijest unit is a quick threading device bypassing the manual half-nut letting you run at normal cutting speeds when screw cutting. Effective but expensive so machine has to do enough threading work to make it worthwhile. Odds are a lathe so fitted will have done a fair bit of work.
PS Muzzer types faster.
Edited By Clive Foster on 06/05/2017 14:14:25
Colchester Triumph 2000 but you must find a good one. Great help to identify where its spent most of its life.
For many years new price and capabilities was attractive enough to sell into manual lathe production shops, training schools, tool rooms, experimental /prototype and maintenance shops. The production ones will be all used up as being well worth destroying for the value of what they made. Toolroom ones will have been worked well but looked after, maintenance shop ones will usually have considerably lower hours but may have been abused. Training school ones probably lowest hours but almost certainly had oopsies. Experimental / prototype shop cast off are the ones to go for, relatively low hours and looked after. Colchesters are not, in practice, economically re-buildable / re-furbishable and generally repairs will only be squeezing out a bit more life from a machine well past its prime. Although not exactly in "wonderful one horse shay, that ran for a hundred years and a day" territory once one important part is worn out most of the rest isn't far behind. Fixing serious neglect or abuse, intentional or accident, being a different matter of course.
You have to think like a businessman with machines of this ilk. Will it do the job? How much capability for how much money for how long? Hobby guy, get it cheap and fix it up as I go thinking, may work for your Myford, Boxford, Drummond, SounthBend and Super Adepts but you will be in a world of hurt and serious trouble with the domestic authorities if you try that with a Triumph 2000. Can do very well by carefully purchasing one with a known fault if the price is right but ... you gotta be sure.
A good test for heavily used and / or unskilled finger-pokened machines is the run up time. Manual gives specifications for time to run up to speed with a chuck on. Any serious deviation means either worn or maladjusted clutch. Even if a lathe has clearly been well used a properly adjusted clutch suggests its been looked after. Adjustment isn't especially hard to do but has to be done by the book so if its wrong you have to wonder what else is lurking.
Check carefully if its obviously been used with coolant. Aprons do collect it and should be drained periodically when used wet. Quite possible to find one that has been run with an apron full of suds for years and still sort of working!
|Thread: Keyway cutting|
Dunno if you have the proper sizes to hand but working to a measured dimension is much easier than sneaking up by cut'n try.
This link gives imperial sizes :- **LINK**
and this one metric sizes :- **LINK**.
With a bit of care and accurate drilling you can arrange matters to leave very little metal in the hub to be filed or slotted out. A CAD program is a great help when sorting out exactly what size drill to use and where to put it. If you plan to file and have a suitable size piece of tool steel its worth arranging a single tooth fixed depth broach on a round bar made a nice sliding fit in the bore. Only good for a couple of thou each side but will clean up the slot really nicely.
Milling is by far the best way to put the slot in the shaft. Quite easy with the dimensions to hand.
|Thread: Murad Bormilathe|
A traditional way to provide repeatably fixed positions to decent accuracy is to use taper dowel pins in reamed holes through both components. Obviously destroys infinitely variable adjustment of the screw and slide system but for pure lathe use 3 or 4 centre heights should be more than enough in practice. Fixed heights makes it easy to sort the tool on centre line issue by simply making a set of spacers. One for each height setting. Means drilling holes and spoiling the originality of the machine. Would be somewhat unfortunate if a hole is misplaced too.
Pull the headstock pin when vertical milling traverse is needed.
An alternative that would probably work almost as well would be to clean up the bottom faces of the headstock and tailstock castings along the tops of the L shaped supports so that they are smooths and each pair mutually true. Spacers could be inserted and the head and tailstocks wound down into alignment. A magnet on the spacer seems a good way to keep it in place. Theoretically best practice is to either let a round bar in top and bottom of the spacers or to accurately chamfer them to narrow contact faces. Line or narrow edge contact onto a wider face being potentially more accurate than contact between two wide faces. Whether the difference is, in practice, of any import if the job is done carefully I know not. Maybe making the spacers in two pieces with provision for adjustment by inserting shims or sliding angled faces across like an adjustable parallel would be a better Home Workshop technique than trying to make everything dead accurate in the first place.
|Thread: Chester Super lux|
Obviously Y axis travels vary with breed and, maybe date of manufacture. The one you looked at clearly has more Y table travel than mine did. More usefully arranged too. As I recall things mine took the spindle centre line from just off the table on the column side to just past the middle Tee slot. My DRO scale was on the front. Although I bought mine from Chester it wasn't actually a Lux, same style, different breed.
A major gotcha with the Super Lux, and similar square column machines, is the limited Y axis coverage of the spindle. Typically the spindle centre line only goes to a bit beyond the middle of the table which can prove very restrictive if handling larger components. The usual general purpose position of the ram on Bridgeport machines lets the spindle centre cover pretty much the whole Y width of the table. A lot more coverage available if you actually move the ram and far more with a bit of creativity.
Another gotcha concerns the relatively large head which can seriously obstruct visibility with smaller work forcing you to peer round the side when you'd prefer to look as near as possible to straight down. A related issue is the limited space each side of the head for setting up. On a Bridgeport you can wind the table over far enough to get the vice, clamps or whatever well off to one side of the head giving excellent visibility for setting up. Heck if you really need room on a big job you can swivel the turret round for unobstructed access to the whole table. Never gone that far myself but been tempted.
This sort of thing, and especially the impact on what you do, doesn't show up on brochure analysis unless you really have your wits about you. I sold my Lux style machine after a couple or 3 years and went Bridgeport because the aforementioned limitations were driving me nuts. Truth to tell I very rarely do work which couldn't have been got onto the Lux, albeit often with considerable patience and creativity, but the Bridgeport is so much easier having the space to make most jobs simple walk up - fix - cut events. That said I remain impressed by the amount of work holding and cutting capability a Lux puts on your bench.
When contemplating any of the larger Home Shop mills I'm convinced that the correct procedure is to assess what capability you loose relative to a Bridgeport. Easy enough to compare basic work accommodation dimensions from the brochure but its where you run out of room that sets the limits and stretches vocabulary. For example drilling at an angle burns up space and smaller machines can be seriously limited in this respect. For something of Lux size maybe consider what you can do to a 6" cube beyond the straightforward vertical drilling and facing or side cuts.
Could be a useful article there for MEW Neil. Mostly drawings illustrating the geometry and space needed for more complex operations. Along with set-up suggestions to win back the 1/2" or 10 mm that makes enough difference to squeeze a job in.
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