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: Threading Problems on Colchester Student|
+1 to what Dave Wootten said. Both his Kerry and your Colchester have single sided half nuts so its easier for the nut to be driven out of engagement from the leadscrew than more conventional double sided "clasp" designs.
Both breeds also have a known history of design revisions in this area suggesting that the system, as originally conceived, was less than ideal.
Half half-nut systems are more common than folk might think. Although they can work well and were attractive to machine builders due considerable cost savings in construction as the actuating and guide set-up can be much simpler the detail design aspects needed to get a system that works well for many years can be subtle.
I once knew a highly skilled machinist with a Kerry in respectable condition who considered verifying full half nut engagement before each threading pass part of the normal operating procedure. As far as I know he never had an issue but he felt it essential to make sure there wasn't going to be one. Not gonna argue with a man who considered cutting an acme screw and nut pair with about a tenth thou backlash routine.
Edited By Clive Foster on 17/06/2019 13:21:08
Edited By Clive Foster on 17/06/2019 13:21:43
|Thread: Dro scale positioning|
The main problem with mounting the scale, particularly glass scales, on the front of the table is clearance for the Y-Axis feed handle.
When I fitted the scale to the front of the table on my old Chester Lux / Rong Fu style square column bench mill I was able to find a suitable handle with a long centre spigot giving sufficient clearance for the scale. This was a disk wheel with folding handle style which actually stuck out less than the originals when the handle was folded in giving more room to move past without being tagged!
Alternatively you could simply replace the standard dials with a suitable hollow spigot having an extended end to take the handle thus moving it further back. With a functioning DRO system there seems little point in retaining the dials. If it does break you can always go back to standard.
I mounted my scale on standoffs leaving a slot to get at the stops behind the scale. It worked adequately but, in retrospect, Johns system with a bar in front would have been well worth the extra effort to make.
|Thread: Worx 20V drill issue|
Throw it back and pay the Makita (or other decent brand) brushless drill tax. Twice the price but considerably smoother all round and longer battery life. Looks like the steam is running out of the buy a cheap one and use it till it breaks idea. The good brands have got much better without being significantly more expensive.
I've been happy with Makita for years and found the switch from NiCad to Li-ion a big jump in performance. Being able to use the same batteries on several tools is big attraction. My 18 V Makita has almost scary torque levels. I got my Makita stuff from Fastfix who do decent prices and fast service. There are other good outlets. Biggest problem with Makita is the huge number of model type numbers. Need bit of analysis to be sure that what you get is what you expect. Screwfix offers can be good but essential to check the numbers as you rarely get a good price on the real beasts. If you do swop for Makita make sure its LXT batteries.
OT but the Makita dual battery hedge trimmers and streamers are total beasts!
Definitely turning into a cord cutter. Only planer and circular saw are still wired and that will almost certainly change next time I have a proper project.
|Thread: Noise Cameras|
Accurate to few inches single box camera mike can certainly be made. Probably at reasonable cost too these days. To my certain knowledge several potential technologies were investigated by MoD for other duties during my time at RARDE / DERA / DRA / QinetiQ and potentially practical techniques identified. A couple or three passed more or less my way with enquiries along the lines of "could something like this be built" and go a "yes but it will cost" answer. No doubt that if someone wanted it badly enough it would be made to work. £500 a box at China Inc costs for the innards plus the fleece the taxpayer surcharge.
Far as I'm aware the proposals fell down on tactical doctrine, deployment, and cost benefit issues. Acoustic gunfire location is, of course, an established and readily deployed technology but that is simply bearing and, usually, limited range data.
Whole idea is stupid over-complication anyway. Sound source tracking and analysis along a road is pretty easy.
|Thread: Chinese speed controller|
Sounds like you only need a fixed low speed for checking things not a full range variable speed system. If so its probably better to investigate some form of mechanical speed reduction. Using poly-Vee belts a two stage "back belt" style system can be made very compact with a dog clutch to change from normal to low speeds. There are a couple or three designs floating around. But that assumes you have appropriate Model Engineer to Home Workshop metal bashing facilities.
If you've not got metalwork facilities maybe look into the imported sewing machine motor and controller units which are generally said to have a speed range from 500 to 4000 rpm. Claimed maximum power is usually round 500 W, 2/3 rd HP which should be plenty.
Just arrange mounting and swap pulleys. Easy enough on a bench mount but a Mardrive cabinet may be harder.
Typically in the £80 to £100 region. Less costly than a 3 phase motor and proper VFD set-up. Supplied as a complete unit so it ought to just work. Made by the million for commercial sewing machines so ought not to have quality worries. The Tag, Sherline and other mini-machine communities generally speak well of the devices.
|Thread: Should I have 3 phase supplied to my house?|
If my experience is anything to go by getting a sensible all inclusive quote for 3 phase being laid on isn't easy. And having been quoted how do you know if the figures you got are reasonably sensible or not without comparison to what other folks got it for.
Really when initially thinking about something like that well outside your experience its good idea to ask around and find out what folk actually paid when all was done and dusted.
Certainly in my case there were big differences in what I got and what it ended up costing between initial enquires and firming up for the work. Even then the bill was perhaps 20 % more. Fair few hidden extras I found. The original basically covered opening the "road" and making standard joint and laying the cable up my trench in the drive. Plus trenching the "road', plus signing, plus covers, plus remedial works on the main cable, plus connection after the cables were in. I had to pay for the cabling too of course. Bit annoying to find that I had to pay to have the original incomer connection removed and re-jointed after it was condemned as dangerous. I got off lightly on the road side of things as the electricity folk accepted that the lane I live in was technically what I was told is called a "Public Street" essentially owned by nobody yet freely accessible by folk at their own risk. So not even considered a footpath so no permissions needed for work outside my frontage.
I lay serious odds that an experienced contractor would have got things much cheaper.
Of course the ever falling price of VFD boxes has made the whole thing something of a white elephant. Although some of the prices on HASS TM1 and the like relative to what can be got for a good Bridgeport with all the trimmings are attractive!
Hafta say I spent a lot more than that getting the supply in, cable laid to the workshop and everything ready to hook up. Then couldn't find anyone willing to do the actual connection and commissioning work for me. Gave up after 4 "yeah I can do that" followed by no shows and/or silly quotes just to lay wires in the workshop leaving me to arrange all the safety and commissioning details.
Utility backroom folk were quite helpful as to what procedures needed to be followed but clearly proper signing off would be needed and that i could not find.
So if planning such work I'd say first catch your electrician and verify that he / she is actually up for the job.
Dunno what happens with new domestic three phase connections in these solar panel, smart meter and supplier switching days.
At least I got the single phase incomer modernised and made relaible. I knew the old one was um "iffy" around end of garden / road area but whata ctually came up was something of a shock to boith me and the electricity folk. Usual four guys on the job. Two to work, two to watch plus an inspector calling at second tea break!
Nice job. Done quickly too.
Way covers are great but one piece ones can be restrictive.
I made mine as 4" (approximately) fold up sections from offcuts of the plastic shower wall / ceiling panels sold by the likes of IPSL et at. Simple tape hinges. Loads of stock so throwaway when they get tatty (must do some more!).
But I have two vices and often work direct off the table so a bit of flexibility in the cover system saves a lot of cleaning down.
Re the shower wall / ceiling panels. Ace in the kitchen as they are wipe clean, I like them everywhere else in the house but the finish and patterns might not be to everyones taste. Great cover-uppers for a "getting old, needs to come down ceiling". Saw to length, hook the tongue in the groove and bang-bang-bang with the staple gun beats the heck out of mega-mess from pulling a 70 year old ceiling down! Stained wood moulding glued round the edge finishes the joint to the wall nicely.
|Thread: Hexagonal Socket Drive|
Its not point contact but the load area can be pretty small. Essentially hex and spanner distort until there is enough contact area and shear line area back to the main body of the head to carry the load.
Depends on the way the head is made where the shear happens. Ordinary homogeneous hexes usually swell as part of the shear process giving more contact area often enough to get it off one last time if galled or corroded on.
Those modern hard faced due to cold forming thingies don't deform much. usually just wipe the whole corner off. The cheapie integrated washer and tapered hex ones being the worst. I want a quiet work with the guy (or gal) who thought they were a good idea!
As for figuring out whats going on thats a job for hybrid analogue - digital computer. Digital to set the basic parameters. Analogue to run the graphs out just like that and ensure you don't hit garbage in garbage out.
interesting analysis but the resistance to rounding off issue has more to do with goodness of fit between the nut and spanner than raw geometry. Obviously the spanner has to have a certain clearance between itself and the nut so it can be put on. Once the clearance is taken up the force will be concentrated on a relatively small bearing area close to the tip. The slacker the spanner the smaller the bearing area and the more readily the nut will round off.
Nightmare calculation especially when considering 12 point ring on a hex head. Presumably a graph of slackness v strength could be plotted but you'd need to take into account the actual material properties as the shear line will be on some sort of diagonal below the corner. Classic example of that are the modern bolts with surface hardened heads due to the cold forming process. Very strong if the hex is undamaged but far weaker if its anything more than little imperfect.
Flank drive was developed as a response to that problem. Theoretically pushing onto the flanks gives a lot more metal to resist torque as the loads aren't concentrated at the tips of the hex or square.
In a practical world both hex and square can be made strong enough but hex is better for access as giving 6 bites per turn rather than 4. More with correctly offset spanner heads. 12 point ring for same more bites reason as offset open ended spanners. 12 point carried over into socket but not so needful if you have a strong ratchet. Still handy with a breaker bar tho'.
|Thread: Coolant Flow Rates|
Further to my previous post FogBuster effect is what you need in the home shop. See **LINK** for nice pictures of the difference between mist and entrained droplets.
A bit of googling will turn up quite a bit of information on mist coolant and microdrop lubrication / coolant systems.
Good picture of the basic operation principle here :- **LINK**
Cooling is by evaporation of the water in the coolant mix not, as in flood systems, by washing. Probably less effective in the limit but much less messy if you can stop the mist going everywhere. The amount of oil needed to to lubricate the tool and promote smooth escape of chips is tiny. Hence micro drop systems. If you can get a narrow stream pointed down drill hole they are pretty good when drilling too. Not in the same class as pukka systems but chips come out much better and the cutting edge stays clean. Even with super gum alloys.
Mine are Bijur Spraymist units as per picture here :- **LINK** . Basically a cast aluminium tank to hold the coolant mix with built in air pressure regulator and solenoid switch to control the low. Valve body with coolant and air inputs with needle valve to adjust how much coolant is delivered. Also usually fitted with non return check valve on the coolant input to stop it draining back when the air is off. Takes a while to fill the delivery tube otherwise. The silver swan-neck coming out of the valve has a coolant pipe down the middle running to a concentric jet at the end. Inner jettakes the coolant, outer part takes air. Airflow picks up the coolant coming out of the jet turning it into a mist which then sprays onto the work.
All very professional. Spendy too. Used units are usually gummed up to the wazoo and caked whit 'orris so budget for serious cleaning.
Import version for around £10 are like this :- **LINK** in many variations. Bring your own reservoir and air. Most have a simple tap rather than a solenoid.
Main issue in practice is too much mist in the air producing an unpleasant fog. Not nice to work in. Mostly due mishandling but, if my Bijur systems are anything to go by, basic air delivery rate is too high and output nozzle too small. Lots of word all over the internet about how to reduce fog but to my mind main issue is to reduce airflow and enlarge the nozzle to produce drops rather than a mist. Lower airflow reduces cooling effects and chip blowing but stops bounce back of coolant mist. As per previous post it seems to have worked.
Ha! I tamed the Bijur Spraymist.
Decent size alloy job up on the Bridgeport, nice finish needed on something not flycutter friendly. Groaned and set the spraymist up. As expected it very much wasn't playing ball or reliably spraying coolant.
So I went all Taz on it and shoved a number 60 drill up the nozzle. Result. At around 15 psi droplets on the work, pretty much no bounce back mist and still enough air oomph to shift the swarf.
So I suspect that one of the inexpensive import mister / mixers would work pretty well at around 15 or less psi if you run the coolant container at the same pressure as the air. Narrower airstream than the Bijur gives would probably be better. Maybe an annular shroud open both ends so some air is drawn from the rear to restrict the dispersion of the air and entrained coolant droplets would work.
|Thread: Newnes publications|
Not sure about booklet or magazine (with binding service) format but certainly similar were produced in the post war book format. As was Practical Electrical Engineering.
Unfortunately Newnes, unlike Caxton, didn't list all the other series then available on the flyleaf.
Complete Lathework in two volumes with datasheets along with the wartime predecessor Lathework in a single, slim, volume.
Complete Gas and Arc welder also in two volumes.
Complete Engineer in four volumes with data sheets.
General Engineering Workshop Practice in five volumes with datasheets.
Also the aforementioned Practical Electrical Engineering again in five volumes with datasheets.
And the related Newnes Engineers Manual data handbook.
Pretty sure there are others too but how many engineering related I don't know. One on plumbing for sure that i didn't buy.
The Caxtons equivalent series covers more titles and subjects but that is a list for another (long) post!
Edited By Clive Foster on 07/06/2019 18:33:55
Edited By Clive Foster on 07/06/2019 18:57:54
|Thread: Difference in spindle sizes|
Atlas nose thread is always American 60° form. Original, flat belt driven Boxfords were the same but it was changed to Whitworth 55° form later. I think at the same time as Ver belt drive was introduced.
Have heard suggestions that it went back to 60° form at some time but the three I've handled were all Whitworth.
Parallel register sizes do vary a bit. Nominally the same but "it" might not screw on or it might be a bit loose. Thou or three variation. Depends o the actual machine(s).
|Thread: Hexagonal Socket Drive|
Slight topic drift but reading through Robetts Snap On link I saw :-
"The Weidenhoff Corporation of Algona, IA was acquired in 1956. This brought the manufacture of automotive test equipment into the Snap-on line. Voltmeters, Ammeters, Distributor and Alternator Testers and the Anal-O-Scope"
?? For cars!! ??
The last being somewhat unfortunate branding. Even by American standards where insertion of -O- in the middle or i on the front seems to be an irremovable national trait.
Apparently over 1/4 million in the largest collection.
First reaction is "How the beep do you end up with 1/4 million, presumably, unique designs?". Even if a lot are variations on the themes of "Fred Bloggs' Superstrong Cheese".
Second reaction is "How the beep does anyone find the time to locate, collect and catalogue 1/2 million labels." At 12 hours a day thats around one a minute for a year. Um "Does not compute!"
|Thread: Coolant Flow Rates|
Dave and Andrew have it nailed.
For typical home shop cutting rates the amount of cooling and lubrication needed is very small. I have ex-professional Bijur Spraymist systems on my machines. The big issue is getting reliable lubricant delivery at sufficiently low rates. Unless you are cutting hard, which should be in an enclosed machine, there shouldn't be enough oil in the air to cause a problem. Bad atmosphere means far too much lube and too high delivery pressure. True mist rather than droplets, lots of bounce back and stuff flying everywhere. No doubt that lubrication makes for more reliable working, better finish and longer tool life without having to work at it.
Decent air blast is handy when milling to clear chips but the oil delivery should be even smaller. My considered opinion is that the Bjur systems don't, and can't work, as they are supposed to. Massive over delivery of lubricant seems designed in. Mine can approach being OK but need careful tuning along with careful aim of the blast. The swan neck tube isn't very good at precise positioning.
A one day some day maybe (if I live long enough) project is to investigate home brew microdrop systems. Import mist delivery systems are around a tenner from the usual auction site so thats the basic hardware sorted. My Bijur reservoir units are fine and dandy so really for me its a matter of figuring out how to drip tiny drops of lubricant into the airstream without driving it into mist. Maybe jiggering around with the innards of a fuel injector off a car would work. Or maybe something could be done with an ex printer inkjet nozzle and driver. Certainly an inkjet nozzle or two looks to in the right volume region. Probably need drilling out tho'.
For air supply on a full DIY build perhaps one of the cheap, low pressure high volume paint / fence protection sprayer pump units would be a good starting point as they are supposed to run happily for long periods. I think modern units run at around 10 to 15 psi. Fine for lubricant delivery as you just want the drops to flop onto the tool and job with no bounce back but maybe not enough for milling. Ideal would be the old Binks-Bullows Hydrovane type units. About 45 psi max and, apparently, built to run for ever. I hook mine up to the Bijur systems when I can't be bothered to run the big shop compressor. Air blast alone is sufficient to clear chips at my milling rate. Trouble is the are getting a bit of cult status. Over £100 being asked on E-Bay. Mine was "dunno what it is mate but I'll take a fiver" at a boot fair.
The 1024VSL has flood coolant which tends to get used about every second blue moon on obdurate materials, usually when threading. Seriously messy and getting the stuff out from under the saddle inspires "creative" commentary.
Bottom line is that I still work dry most of the time.
Edited By Clive Foster on 07/06/2019 11:51:30
Edited By Clive Foster on 07/06/2019 11:52:16
|Thread: Connecting a pair of motor controllers.|
Given that many, even low priced, controllers will take a speed reference input its worth looking at the cost of providing effective output speed detection for the motors and using that to control them via single reference.
The continuing march off China Inc and the ever decreasing costs of electronics has made many "best solutions" that used to be considered far too expensive affordable. Indeed its often more expensive to do things the old, simple way, than the modern complicated, integrated electronics way.
|Thread: before superglue|
Although the nominal joint strengths are very similar one important difference between adhesive bonding and soldering is peel strength. Adhesives are generally much weaker than solders in peel because very high stress concentrations can be developed at the separation point between the bonded surfaces. Sufficient to tear the bonding material apart or pull it off the surface if initial preparation was inadequate. A little bit of additional mechanical locking at the ends of adhesive joints is often appropriate.
Oversimplifying adhesives rely on surface wetting to generate the bond strength whilst properly applied solders have a degree of inter metallic penetration which is inherently far more resistant to localised joint line stresses. Its not actually that much stronger. You just can't build up the localised stress. Peel is good test for improperly tinned and improperly heated soft solder joints. The joint may look fine but if it hasn't taken properly it will peel quite easily. One of my mentors showed me that many years ago. Much to my surprise as I thought I'd made a nice neat joint. Big electric soldering irons aren't quite as easy to use as I'd thought.
Adhesive joints can be amazingly strong as its relatively easy to cover quite large areas. The achilles heel in the home shop is surface preparation and environmental factors. Usually temperature. Its hard to achieve and maintain optimum conditions in the home shop.
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