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Member postings for Paul Kemp

Here is a list of all the postings Paul Kemp has made in our forums. Click on a thread name to jump to the thread.

Thread: Opinion on using blue Loctite (thread locker) on clocks?
27/01/2020 00:59:00

To take SOD's I think excellent post a little further, compare loctite to CNC machines. Both are relatively new developments in 'engineering' and both have a justifiable argument for use. Loctite used in the correct way is an excellent medium to assist in production, assembly and longevity of the product. It can reduce the need for close precision for press fits to a wider tolerance band making production cheaper, it can make products easier to assemble not requiring press tools or heated shrink fits it can also replace traditional locking mediums such as spring or serrated washers again cutting weight and also assembly costs.

CNC machining is an excellent development making components easier to machine, machining items that previously could not be or would be very difficult to produce and once correctly programmed and set are capable of churning out parts to close tolerance with minimal human intervention (which is expensive) so parts can be made quicker and cheaper increasing profits or cutting cost to the end user.

So for both there are good convincing arguments based on economics and performance why CNC machines and Loctite are part of modern production.

Again considering SOD's points, clocks have been hand made very successfully for 100 years plus before loctite was invented. One would assume (and I have little idea about clocks and watches apart from they are too small and fiddly for me to be attracted too) that if screw threads coming loose was a major problem then Loctite would have been something like the holy grail to the industry and every watch and clock now made would be assembled with the stuff and any old pre loctite clock or watch you find would have a bunch of loose screws laying in the bottom?

I think the answer to the question is if it makes you feel good, slap it on but in essence if it ain't broke, don't fix it!

When working on old stuff, particularly vintage engineering stuff using modern materials and methods to bring about perceived improvements is often frowned on when purists are examining the provenance of the article. Keeping to the traditional skills and materials is deemed very important and even old clumsy historical repairs are considered part of the articles life story (like the bent nail in the weight - sure it wasn't made that way but because the nail was put in the clock survived being scrapped because it was put back to work). If you want to develop a reputation as a skilled restorer and craftsman Loctite is best left on the shelf.

Paul.

Thread: Silver soldering 19mm steel.
25/01/2020 00:11:06

As Hopper, nozzle too small, look for the 1" plus one that came with the torch and screw the regulator in to get a decent flame. Looks like it took too long to get the job up to temp and your flux was burned / beads indicate temp not high enough probably the rod melted by the torch rather than by heat of the job so it didn't flow. Make sure your home made fire bricks are not absorbing heat but are reflecting it back to the job.

If you can find a commercial lagging company see if you can bag some off cuts of the white mineral high temp insulation mat (various trade names). You need a company that insulates steam pipes, exhaust pipes etc. Stuff comes on a roll in boxes about an inch thick, quite expensive to buy but on lagging jobs there are always trimmings of reasonable sizes. Price of a pint to the lads will get you plenty. Lasts well and it's really effective.

Paul.

Thread: What geen grinding wheels for tools
24/01/2020 23:42:03

First answer from Brian is good advice especially not going too fine on the grit. Just stick one on one end of your existing grinder. If the work is that fine you need to hone the tool there are plenty of diamond slips for small money. I use a single diamond on a stick to dress my wheels and don't find it particularly hard to get them flat. If it's a problem make a collar with a grub screw to fit the stick and use it against the back of the rest, rolling it across the wheel.

There is loads of flashy stuff you can get but you can get plenty good enough results with the basics.

Paul.

Thread: scam alert
24/01/2020 23:28:43
Posted by Windy on 24/01/2020 14:03:40:

It's not that easy at times what you think might be a scam sometimes is genuine.

I got one on a survey of my bank so did a face to face check with the bank concerned before I opened it.

A genuine survey and they did not need personal or financial details.

Banks etc.I physically check with them I do not use the phone or email to talk to them.

If only we still had a bank you can visit! My local branch which was 5 minutes walk away closed a couple of years back, now the only option is to drive 10miles, use the park and ride for £5 to get into town as there is no parking close by. Could catch a bus, that costs just under £10 return. You can write off half a day at the same time. Such is progress, we will all be stuffed if tinternet goes down!

Paul.

Thread: Only for Myford lathes
22/01/2020 23:13:21

Inserts don't tend to like interrupted cuts, you might have got away with it but you might have used the same number of inserts as you sharpened your HSS. I suggest your brazed carbide tool wasn't sharpened correctly and had not enough if any at all clearance on it. Many brazed carbide tools are supplied as a blank canvas and are not sharp at all, relying on the user to add the correct angles prior to use. Did you sharpen it and try again? You really need a green grit wheel to sharpen them. A carbide tool will cut anything an HSS tool will. I suspect if they were through hardened they were a higher carbon steel than mild but they couldn't have been that hard or your HSS wouldn't have touched it.

Paul.

Thread: Hall Class Display Model
22/01/2020 22:58:55

Looks good, nice to see something different. Are the wheels laminated to form the flange?

Paul.

Thread: Gipsy manifold material
21/01/2020 00:45:41
Posted by Tim Stevens on 20/01/2020 18:19:24:

Brass has an expansion coefficient very close to that for Al alloys. The value for Steel is rather less. I suspect this might have been one factor in the mind of the bloke what made it.

Cheers, Tim

Not sure I follow your thinking there? Steel top, brass bottom, sounds like a recipe for a banana to me? As it's the inlet manifold would it actually get hot enough over its length to make any appreciable difference? If it were the exhaust a different story maybe. If you are suggesting coef of ex to match the aluminium crankcase then that only holds good if the whole thing is brass?

Paul.

Thread: Compressors
20/01/2020 22:43:43

Not sure what pressure they attain? That have a reasonable volume but pressure would drop off quickly so personally I doubt it but prepared to be proved wrong!

Paul.

Thread: Can we have a really clear distinction between Silver Soldering and Brazing
20/01/2020 22:22:40

Silver solder contains a proportion of, wait for it, silver? Brazing filler rod is mainly brass. Silver solder has a low viscosity when fluid and flows easily into small gaps - essential property that is always laboured. Braze has a higher viscosity when fluid and likes bigger gaps. Main differential between basically the same process is the temperature it becomes fluid at. Silver solder more suited to smaller sections and potentially lower melting temp parent metal and whilst fillets can be formed they are relatively small. Braze better suited to bigger sections and higher melting temp parent metal and capable of forming larger fillets.

Paul.

Thread: Centec 2a Gear Box Oil
20/01/2020 22:13:19

Smith and Allan will have something suitable.

Paul.

Thread: Silver Soldering Brass
20/01/2020 22:08:46

Bexley Heath, Hempstead Heath, too large?

Paul.

Thread: How to soften steel
19/01/2020 14:22:57

Good spot Jason. Revolving centre that revolves should have still gone round though despite being up against a hard edge? Maybe excessive pressure from the tailstock too? Maybe as Journeyman suggested it wasn't the revolving centre in the picture he was using, that would do it. No sign of grease or tallow though if it was.

Paul.

19/01/2020 12:56:00

Picture looks to show a rotating centre if that is the one being referred too. Appears to have a couple of round holes in a retaining ring holding bearings for a peg spanner? You need to be doing something wrong to screw the point on a rotating centre if the bearings are ok!

Given we now have a catch plate on the back of a chuck, reduced thickness slide to take a monster tool post, desire to use oversized tools and a knackered centre, this journey isn't going particularly well. I think the OP would do well to take SOD advice and slow down a bit.

Paul.

Thread: Compressors
19/01/2020 12:42:30

David,

Good advice from Paul. It's a bit of a minefield as compressor sellers often exaggerate their claims! Short answer is get one as big as you have room for and with a motor that can be supported by the power supply you have available, pretty well all hobby machines start on load so starting current is the limiting factor.

I think if you want to try to calculate it, work out the displacement of your engine cylinder (bore X stroke), double it (because it's double acting) and multiply by the maximum speed (rpm) you want to run the engine at (say 30?). That will give you a volume per minute at atmospheric pressure. Your compressor then needs to deliver more than this to maintain any pressure in the reservoir. A larger tank will give you a greater buffer.

Paul.

Thread: Why is my silver steel undersize
18/01/2020 18:21:11

That's a little more than a thou. What are you measuring it with? I have just measured a piece of 3/8" with a Starret 0-1 mic and its bob on 0.375. As you say all the bits you have you have measured are undersize maybe it's your instrument?

Paul.

Thread: Silver Soldering Brass
18/01/2020 18:03:57

Not sure about 'dials' with a 3.5 bar range if you are looking for less than 5 psi. 3.5 bar is around 50 psi so using a gauge to measure 1/10th of its range is not going to be terribly accurate? I know nothing of the Smiths torch or the bottles it will be combined with but usually oxygen and acetylene regulators have a gauge on either side, inlet will be high reading showing cylinder pressure and giving an idea of contents, outlet will be line pressure to the torch. Also be sure to understand you generally screw regulator control in to increase pressure and out to reduce.

Paul.

Thread: Myford super 7
18/01/2020 00:45:50

0.004" is in finishing cut territory, it's a mere kiss. In fact a cut that small is not great generally with anything carbide unless using one of the polished aluminium style tips. If you have taken a cut of that size and the tool is sharp it shouldn't cut anything bar maybe rubbing moving back. With everything set right you should be able to take a 0.050" cut without too much stress for roughing if you have a bit of free cutting stuff. When roughing out I generally take as big a cut as the job / machine will stand and approaching size decrease the size of cut to end up with a finishing pass between say 5 and 10 thou dependant on tool and material. On the myford the lead screw is generally left set up at 0.004" per rev (because I don't have a quick change box on it and I am lazy swapping change wheels!). Depends on the material and tool but usually roughing I just wind the saddle back to the start and put on the next cut, final pass I note the reading and back it off before winding the saddle back. Hope that helps. You will develop a feel for what's right and what works in time.

Too fine a wheel will load easilly and require regular dressing, I have a "medium"' standard wheel one end of my grinder and a green grit the other which covers all my off hand grinding needs for HSS lathe tools and drills and brazed carbide lathe tools.

Paul.

Thread: Ally Pally Exhibition
17/01/2020 23:41:31

Well I went today. I wouldn't say it was any better or any worse than last year, it wasn't bad but it wasn't great!

There were a lot of good models to look at, the detail on some of the motorcycles on the stand along the back wall was very impressive. Some nice boats too. I would say the balance in model types generally continues to move away from the 'engineering' base towards boats, planes and trucks. Not necessarily a critiscm as I appreciate the different fields and skills involved even if they don't really totally grab my interest. I find the radio control trucks and diggers fascinating to watch but it's not something I ever see myself getting into. Was impressed by the large planes. Was also nice to see some of the 'ordinary' models that obviously have done and still do a days work on the track. Loco's that are not polished to perfection, have the odd brush mark in the paint, file marks on the rods etc. These are more likely to inspire people to have a go I think than the traditional gold medal winning, flawless exhibits. Not decrying perfection before anybody rips my throat out, I just observe it as perhaps intimidating to the ordinary bloke in his shed just starting in the hobby! Full marks to the two bigger club stands, Chelmsford? (Sorry not good with names and places) where I watched a couple of people have a go at firing on the simulator, water on, pressure dropping and the wheels slowing down, coal on to try and bring it back, what a great way to demonstrate boiler management! Also the repair shed, well deserving of their prize. The fellow on the mini lathe on the SMEE stand facing a bit of aluminium worried me when he adjusted the tool post with the chuck spinning. Ornamental turners were amazing, again not something I could see myself doing but very clever stuff!

Traders; well done RDG, with Warco gone they obviously had the edge on engineering tooling, also good to see Tracey tools still supporting the event. Home and Workshop machinery still I see maintaining their gold standard pricing, indicative maybe of the costs that have to be covered by the traders? Metal prices seemed to vary widely, I bought a lump of bronze from Polly Models which College seemed to be selling for twice the price?

I usually travel up with 4 or 5 other club members, this year I was on my own, one having just had an operation, one dog sitting, one not wanting to make the journey, not sure on the others. Usually I meet at least half a dozen people I know, today only one. When I arrived about 11.00 there was a healthy queue still for tickets but inside it didn't seem terribly busy. Buying a coffee at the pizza outlet just inside the door about 14.00 I was the only customer and with the price less than £2 that couldn't have been the reason! I spent about £80 between various traders, a rake of tips from JB Tools, a length of stainless bar, aforementioned bit of bronze, an ER 25 ball bearing nut from RDG and a few other knick knacks to stock up so I didn't make anyone rich! Other than RDG I didn't have to wait to get to the stock for the crowds in front to disperse it was a case of walking straight up to the stands and making the purchase.

Will I go again next year? Probably but because it's what I usually do (and as another said because that's what I did with my dad going back to the Seymour Hall days, then Wembley) rather than because it was a great inspiration and uplifting experience! However if the traders dwindle further I think I will seriously question if the 2 odd hours each way and the cost of travel plus the entrance fee is really worth it! I can't put my finger on why I wasn't feeling it was a really great day out on the way home, I just didn't think it was! It wasn't a bad day out it was just OK.

Paul.

Thread: Myford super 7
15/01/2020 23:32:59

When I did my apprenticeship all the lathes had 3 jaw chucks, somewhere, mostly unused. 3 jaw chucks were considered poor on holding power and little if ever fitted, even frowned on unless you were holding hex bar. 4 jaw was the order of the day. 4 jaw is so much more versatile for odd shapes, off centre work, no problem with special reverse jaws, you just turn em round, you can even have some one way and some t'other. In terms of running true, they can be bang on, every time. It's hardly a problem to dial a job in and if it takes 5 mins in a hobby setting no real problem. If you want true in a production setting collets are the answer. I can't see 2 1/2 thou runout on a 3 jaw as a problem.

Paul.

Thread: VFD Question
15/01/2020 23:08:03

You might find 12rpm quite a comfortable speed for cutting say a 4tpi square thread or even a multi start thread

Paul.

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