Here is a list of all the postings Steve Pavey has made in our forums. Click on a thread name to jump to the thread.
|Thread: Calling all Apple Experts....|
I have also removed screens - it’s a bit daunting when the screen you are removing is perfect and you want to stick it back in place, but in this case as it is broken and you will already have the replacement ready to fit I don’t see the problem - as Circlip says, you will need a hot air gun and a few other tools (mainly plastic spudgers and/or old credit cards. I always use the iFixit site for repairing Apple stuff - the photos are clear and the instructions good.
|Thread: 6x4 bandsaw|
Dismantled the carrier for the top/front (idler) wheel - it slides between two plates which locate in grooves in the carrier. I filed the bolt holes so that the two plates can be pushed well home into the grooves - this reduced the play in the top wheel - some play is inevitable given the geometry of the whole arrangement. Then another realignment of the two wheels after reassembling. I rebuilt the saw completely when I got it a few years ago, with new bushes, spacers, washers etc, so there should be nothing that is overly worn in that time.
A test cut with 25x3 ms was more successful this time. I noticed that the blade slipped on the drive wheel a couple of times so added a bit more tension. As far as I can work out, this might have been the root cause of the problem - the blade may have been snagging slightly in the cut (the first blade always had a slight jiggle at the welded joint, and the second was obviously new and therefore had a good bite to it). I guess it was also slightly out of adjustment too, so the combined effect was to throw the blade off the wheels. A few more bits to cut this evening will show whether it is really sorted out.
Thanks for all the suggestions - always useful to hear of other folks experience.
|Thread: Rotary phase converter|
If you can get a clamp-style ammeter around the line or neutral of the supply to the converter that will tell you the current, then V x I x time/1000 to give you an idea of kWh. It would be interesting to see the difference between when the converter is idling and when the Boxford is running under a bit of load.
Edited By Steve Pavey on 25/08/2020 16:57:57
|Thread: 6x4 bandsaw|
@Simon - it was running fine the other day, then it shed the blade this morning cutting a piece of ms strip. Refitted, check it was ok by manually turning it and it was ok until I lowered the blade onto the work. That’s when I changed the blade for a new one. When it did exactly the same with the new blade I checked the alignment and cleaned the bearing guides.
i gave up in disgust (at myself for not being able to sort it out!) but just about to steel myself for a second go, following the procedure in the guide I linked above to the letter. If all else fails I’ll get the angle grinder out.
I should have mentioned in my post above that I’ve already changed the blade this morning - a new Starret from Tuffsaws. I also should have mentioned that I cleaned the wheels and I don’t use any sort of oil or cutting fluid.
I have a 6x4 bandsaw which has been cutting well for a long time, but has just started chucking the blade off within a couple of seconds of starting a cut. It tracks fine without a load on it. I have read the John Pitkin guide **LINK** , I’ve adjusted the tracking and the blade guides, cleaned the bearings on the guides, but no luck. I have no idea why it has suddenly started misbehaving with no apparent reason, so if anyone has any ideas perhaps you can make some suggestions.
If your suggestion is to buy a cut-off saw or a mechanical hacksaw, then you’ll be preaching to the converted, but I daren’t risk buying another workshop item for some time!
|Thread: Who trains these ideots?|
Someone who has never tried teaching, obviously.
|Thread: Social Distancing|
The woman doctor speaking in that video is Stella Emmanuel from Houston. Trump retweeted her video and it got taken down. She touts hydroxychloroquine as a cure, discounts masks in spite of the current evidence to the contrary, and as MickB1 says has some crazy notions about aliens and dna. She is part of a group of doctors known to be part of a very right wing group which backs Trump. In short, the whole video is a few credible but unproven claims backed up by unscientific and sometimes plainly wrong assertions, all of which have been comprehensively debunked by a number of more credible people.
yes, we should be open minded and look at all the possible means of transmission and infection, as well as all possible means of treatment and prevention. But we don’t have to be so open minded that our brains fall out. And is wearing a mask really that difficult? Even I can manage that.
Edited By Steve Pavey on 03/08/2020 12:08:33
|Thread: Music in the Workshop|
Pink Floyd. Not a fan of classical stuff (yes I know, philistine). Like Bob Stephenson, opera is banned, along with musicals. When Floyd has been exhausted then Genesis, Queen, the Stones, Stevie Ray Vaughn, John Mayer and a long list of similar - all on the iPod so no talk and no adverts. Very occasionally R4 gets an airing for programs such as More or Less.
|Thread: Cleaning emergency !|
Oxalic acid - obtainable as Y10 (a gel) from a marine chandlers, or as Bar Keepers Friend (a white powder, applied with a wet cloth) from a hardware store or ironmongers. It’s excelle all sorts of stains, nudging rust stains from Formica incidentally.
|Thread: cutting upholstery foam|
Hot wire stretched between two blocks?? Might be possible if you do it outside, as I expect the fumes are not all that pleasant.
I’m sure you’ve already discounted two other possiblities - a very big bandsaw and buying new 4” foam.
Edited By Steve Pavey on 31/07/2020 14:19:45
|Thread: Completing posts|
I think (and hope) I have always posted my thanks on here for help and advice I’ve received, but with one exception - a very helpful forum member loaned me an engine hoist to help with getting my mill from my van to standing vertically on terra firma. While I obviously thanked him in person both when I picked it up and when I returned it, I felt it may not be helpful to post my thanks publicly on here in case he was subsequently inundated with people asking for favours. I’m still not sure it was the correct thing to do! Not only did I get the loan of an engine crane, but also a guided tour of his workshop, an introduction to his friendly dog and an interesting chat.
She is clearly wearing some ppe. And she doesn’t look like a typical ‘model’, so while the picture may have been posed I don’t get the impression that it isn’t a typical working situation that has been photographed. To me it shows someone unplugging the test leads from some sort of engine test rig, so why would anyone need to worry about the long hair and necklace? There is a bloke in the background with a high viz jacket, so clearly he does a different job. The need for ppe is related to the job being done, which is probably why she isn’t wearing Kevlar chainsawing trousers and a life jacket.
|Thread: What did you do Today 2018|
The change to SI units came when I was struggling with thermodynamics and structural engineering at university. It made life so much easier for me. But like Neil, I have struggled with the cross slide on the metric lathe, so I have a little scribble written down on the headstock - 1 div = 0.04, 10 div = 0.4mm - and now life is easy! I don’t know why this particular thing has been a mental block.
On a related note, I watched a Lawrence Krauss video the other day, which demonstrates how convenient it is to work with metric units and exponents to get good approximations - https://youtu.be/h9FurAf4C4g
https://youtu.be/h9FurAf4C4g Sorry, trying to embed a YouTube video on an iPad seems to be an impossible feat for some reason.
Edited By Steve Pavey on 05/02/2018 09:35:47
|Thread: Bronze Alloy|
All the bronzes I’ve machined have been fine - some are surprisingly tough, all of them need very sharp cutters but rarely any problems (except sometimes when I’ve ignored my own advice and used a blunt twist drill on a very deep hole). I would say that 316 stainless is tougher to machine than any bronze I have experienced.
To be honest, since most of the machining I have done on marine work has been repairs and modifications to existing components, it is difficult to know exactly what type of bronzes that I’ve dealt with. I think silicone bronze is one of the tougher variants, and is used for machine screws, bolts and other fixings - I have machined lots of that with no problem. Some so-called bronzes are actually brass (copper/zinc alloy) - to be avoided at all costs because of dezincification (there are some exceptions to this, but not many).
Duplex stainless steels have a different alloy structure,and have better corrosion resistance. Personally, I don’t think this is all that important for a marine application - the difference might be apparent in high temperature applications or with food or brewing equipment, but 316 is perfectly adequate for marine work.
One of the bronze alloys might work as well, maybe silicone bronze for example, but would be more expensive and more difficult to source. 316 is very close to bronze and brass alloys on the electrolytic scale, so electrolytic corrosion is no reason to avoid stainless.
The only real problem with stainless in marine applications is crevice corrosion - caused by a lack of oxygen. It won’t be a problem with something like your rope stripper which is surrounded by a free flow of water. It is sometimes a problem with prop shafts, particularly on the taper where the prop is fitted, and manifests as what appear to be burrows or worm-holes. But even this is not enough to persuade boat builders and engine installers to use anything other than 316 for prop shafts - yes, some older boats have bronze shafts, but I bet 95% of boats have stainless shafts fitted.
|Thread: Meddings Driltrue blowing fuse?|
The Meddings Drilltru model shown on the lathes.co.uk site (a 15” capacity with a ½” chuck) has a 1/3hp motor, so in theory draws very little current when running, probably around 1-2 amps. I would have thought a 7 amp fuse would cope with even the starting current of such a small motor.
Since the fuse is blowing, rather than tripping an RCCD, that indicates there isn’t a fault to earth. That leaves either some sort of mechanical fault (seized or sticky bearings for example) or an electrical fault that is not due to earth leakage- faulty windings or a faulty capacitor or maybe a centrifugal switch that isn’t working correctly. Eliminate the mechanical faults by disconnecting the drive belt or removing the motor completely and running it on the bench - if it runs ok then check that the rest of the drive train spins freely. A bench test will also help to check the centrifugal switch (if there is one) as you should be able to hear it click off as the motor spins down to a stop. You could check the resistance of the start and run windings (the last 1 hp motor I checked had resistances of around 100 ohms on both the start and run windings). If you have a multimeter that can measure capacitance that would also be worth checking - they sometimes start to deteriorate and give strange symptoms before finally giving up the ghost.
A 13a fuse may work but if the problem is windings or a capacitor that are starting to fail it may just mask the real problem for a while. At the moment the 7a fuse is the weak link in the chain which is better than the start windings being that weak link.
|Thread: Am I doing this correctly?|
It spent last season immersed in salt water - a magnet test is really not necessary
As an alternative to Tufnol you could consider either acetal or Vesconite. I have made many cutless bearings and rudder bearings from Vesconite and it performs extremely well - a typical Vesconite cutless bearing for a 1”prop shaft will last for at least 5 years. **LINK**
Both acetal and Vesconite have very low moisture absorption and therefore little dimensional change, unlike just about every other engineering plastic.
Agree with what others have said re gauge plate in salt water - won’t last 5 minutes. 316 is ok to machine with low speeds and a decent feed rate, but will work harden if you let the cutter rub. I’m not sure the shape of the teeth are all that important - you could probably mill the overall shape out and then use an angle grinder to cut the teeth. If you make all the parts from 316 make sure that the blade which runs on the bush has a bit of clearance, as otherwise it will gall up and seize solid, which is not at all what you want to happen.
|Thread: What to buy at Ikea?|
Another vote for the Helmer drawer units - I have two pop-riveted together as a mobile base for my 6x4 bandsaw. Also the Bekvam step stool **LINK** is dirt cheap and very useful if you store stuff in the roof joists of your workshop, or if you want to sit down at the bench.
I’m sure there are many other small items like waste bins, stainless roasting tins etc that can be used for washing parts in paraffin or for general storage, digital scales for measuring out epoxy resin, soap dispensers for swarfega- the list is endless.
Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!
You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.
Click THIS LINK for full contact details.
For subscription issues please see THIS LINK.