Member postings for Ajohnw

Air quenching is mentioned for M42 in the link I posted. That's 10% cobalt. 5% and M2 / plain HSS is available and all will be different. The link also mentions 2ndry hardening and shows what happens with double long term annealing. It's weird stuff.

This shows the hardening problem, it's for steel but HSS is likely to be similar in relation to burning

HSS is heated to 1280C for hardening so my recollection of using 1300C in a muffle looks to be correct. 100C higher and probably oh dear.

If some one has a bent end all round boring bar they might find that only the tip is actually HSS and the bend is actually in the shank that holds it. A test with a file will soon show if that is the case. I have one like this that I bought of Reeves a long time ago. It's a pretty hefty one. Some where I do have small bar that I am pretty sure is all HSS with a daft amount of bend on the end for the size of the bar - eclipse I think, probably sub 1/4" dia bar.

John

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I posted a link similar to this one once - it illustrates the problems well

**LINK**

Part of the problem with hardening is if the temperature gets too high it will burn = nvg.

John

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There are basically several grades for specific purposes, Thread lock - if you ever want to undo it good luck. Another thread lock intended to be undone with hand tools if needed. Then comes retainers. These tend to be for situations with less clearance than threads typically have. Loctite don't appear to offer one but there are grades intended to work in much the same way as nyloc nuts do. I recently noticed a grade suitable for propane fittings in a video.

I generally buy out of date Loctite from a local bearing supplier. It's much cheaper and from my experience is still fine. I used some recently that was out of date when some one gave it to me that must be 15 years old now. Might even be more. It still works but might not have the locking capabilities it initially had. I'd expect to have considerable difficulty undoing it with hand tools. The main aspect with that really is no grease or oil on the parts but I have often used it without going over the top with that and it still works.

Using it is a bit like super glue but not so bad. It's a similar technology which is why there is always air in the bottle. Typically people squeeze a drop out and then loosen their grip while the nozzle is still pointing downwards. It's best to do that nozzle up especially with super glue as it will suck the excess back in. I'm sick to death of telling my son to do that with super glue as I usually have a rather expensive bottle about. He's now banned from using that and I leave some cheap stuff around for him. There are different grades of super glue too.

The Loctite web site used to be very informative but some years ago the company was taken over and last time I looked it was useless. That was some time ago now. Suppliers sometimes have a small booklet around, or they did.

John

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Wh nds vwls. Myb th bst plc t pt ths thrd s dwn a tltt. Crsly mst ppl wll dd th mssng vwls tmtclly bt nt f t strts wth n.

John

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I don't know what the 6mm sq bar is for Brian but the fact that 1/4" sq is 0.014" / 0.35mm bigger might not matter at all. I have a very good none ferrous supplier not far from me and the bulk of their stock is imperial. Over the past 5 years or so they have added some metric stock but only where some one wants significant amounts of it or on certain materials where it is only supplied that way now. The only one I can think of off hand is oddly cast iron. They keep a limited amount of that.

This area is a problem you might often come across so the easiest answer is to consider what are the important aspects of a design. As far as engines go that is the fits of certain parts and timing associated parts.

John

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I buy my rules via ebay.com. Part of the reason is that I use imperial ones but I suspect much better metric ones will be available from the USA as well. Cromwell might carry some in the UK.

To get round Neil's short one I have rigid one with graduations across the ends as well. Also 2 styles of narrow flexible ones.

I usually buy Starrett. Satin chrome if I can. There are usually plenty of types on the site so easy to find.

John

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You could neglect the tempering. I did forge some and harden it during training heating it in a gas muffle. It was quenched in oil - a huge bath of it with plenty of moving it around. I can't remember the initial hardening temperature but it will be about on the web, 1300C rings a slight bell but pass really. The tempering is tricky - holding a precise temperature for some time to let it soak through. I didn't do that and would guess that the job was a foreigner for one of the instructors. A google of heat treating high speed steel will bring up info but there are various grades and that is likely to matter. Cobalt content for one.

Edit - take up the practice of frequently sharpening with a slip stone rather than regrinding. HSS tools last something like for ever if that is done.

John

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Edited By John W1 on 19/12/2015 16:20:35

You can tell the jaw order by looking at the back of the jaws. If that is out they will be all over the place. I understand that the zero mark usually indicates the position for jaw one - that jaw is the one that can be pushed in least before it's scrolls meet the scrolls in the chuck itself. Jaw 2 goes in further and so on. The scroll in the chuck needs to be wound round so that it's start is just before the 1st slot then each jaw is inserted in turn while pushing on them and closing the chuck.

Just hope I have the position of the scrolls on the back of the jaws the right way round. I do it without even thinking about it or look at the numbers on them. Where the marks are absent the usual trick is to mark them with a centre punch. One dot for one, 2 for two and so on.

You could try rotating the bar just as the jaws close on it - hard to explain and there is a bit of a knack to it. It needs to be rotated when all of the jaws are touching the bar. It probably will help once you have the technique correct.

John

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Interesting question. It seems to be an acid based process so if these are still about water will probably do it. Might be a good idea to use distilled water. Severely de ionised water might have a strange effect. It turns acidic as soon as it's exposed to air (CO2) were as distilled is stable.

There is some info about on the web about how it works and what form of coating it gives. Use selenium in the search.

John

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I've decided to follow John Snow (C4 news) and eat porridge every day. Statin's aren't on for me, joint problems that haven't totally gone away also weakness partly fixed now apart from a torn muscle that may well relate. Also a certain level of short term memory problem that has thankfully gone. My brother had the same thing happen. Might be because neither of us eat much fat anyway.

Toad in the hole might crop up 4 or 5 times a year often less. Making lardy cakes might not be a good idea but occasionally why not.

John

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You can always add sealed ball bearings. They don't need to be big ones, they will only be taking side loads. I keep telling myself to get round to doing it to my boxford steady every time I use it especially on aluminium. Often it's just a case of drilling and reaming fixing holes in the fingers and making the "studs" to support them. The bearing size is set by where the fixing holes need to be in order to make the set up strong. I have used a steady on a very large lathe where this had been done with much smaller bearings than I would be inclined to use. The finger ends were well tapered to allow low diameters to be gripped. As small as they were the bearings still increased the minimum size that could be gripped.

Some people modify the fingers so that they can take various tips - some plastics are favourite. I am not so keen on that method as it wont be as rigid as bearings.

John

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Personally I wouldn't use a self centring 4 jaw for holding round work. They aren't meant to be used for that. Round stock generally wont be perfectly round and 4 jaws can't grip it evenly as a result. A 3 jaw chuck can grip slightly out of round work with an even pressure on all jaws providing the work is set in it correctly but even with these a ham fisted approach can result in 2 of the jaws gripping more firmly than the other one and that will result in more run out than the chuck is actually capable of.

4 jaws just make that aspect worse. You could try rotating the bar just at the point when the jaws are closing on it to help them seat evenly but .you are still likely to have problems. People often do even when using 3 jaw chucks.

John

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I see them as more for facing shoulders in bores Jason not facing the bottom of blind holes. However on a shallow one such as you show there would be little overhang and not much chance of the tool deflecting.

I can think of a number of occasions when I have had to set a tool significantly over centre just due to the size of cut being taken and the size of the bar that has to be used so even the term SLIGHTLY needs qualifying. I would generally see it as meaning thou's when boring or during straight turning. When boring deflection can introduce chatter but often the best solution is to turn the speed right down.

All messed up when deliberately turning well above centre using tools with excessive amounts of clearance but that is a rather specialised subject and needs a pretty rigid set up. That is the other aspect of tool setting. Below centre reduces the clearance angle when boring. Above centre reduces it when turning. This can be pretty critical on low diameter parts

John

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I'll second starrett. I'm ok at the moment. Some on in a builders merchants in Pembrokeshire needed some decent ones and bought a load that were made in France. I bough several after trying one so still have a few left. They may not have any more now. They are on the road out of Milford heading towards Dale in case some one is in that area.

John

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The greens make the meal more healthy. Sometimes runner beans with a bit of butter on them or a stir fry mix of veg. I might try adding onion gravy but feel it doesn't really need it.

I more or less follow the recipe in the free BeRo booklet. As we use skimmed milk I add butter to the batter. Part cook the chopped up sausages in the pizza pan which collects some sausage fat so that stops in. Pour in some of batter so the the heat in the pan part cooks it then add the rest and back into the oven.

Me mom used the BeRo book so it proved useful after I married. I keep meaning to try making lardy cakes.

John

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The tips should be a SLIGHTLY above centre so that if the bar bends it doesn't dig further into the work making it bend more and dig in even further etc. This is the opposite of turning outside diameters where if the tool bends at all it takes less material providing it's exactly on or a little below centre. Here it's more a case of setting slightly below centre to be more sure that it isn't above. Just good practice in other words unless some one wants to deliberately turn with the tool above centre.

Boring bars are far more likely to bend so are more critical in this respect. The amount needed depends on the bar and on the size of the cut.

John

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I prefer to just eat toad in the hole with some veg rather than with a jacket potato etc. The problem with the usual pizza pans is that divided into 3 which includes a smaller portion for my wife it isn't as filling as both of us would like. I also have to give my son the biggest, just, portion. The 13" dish provides 39.7% extra over our so called 12" pizza dishes that are around 11" at the base. Round, well combi ovens rotate the food while it's being cooked. It tends to provide more consistent results than our main oven.

I could get the 14" dish in the main oven.

John

PS There are some stirling engines about that are based around borosilicate test tubes.

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They would be pretty good for rather large round shortbread biscuits Norman - well spotted. They could be mounted on a rotary table and the segments milled out - of the biscuits of course.

John

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I did think about posting something short and sweet on the end of the get this "ambiuous" posts thread but then thought this might be of use to more people.

I'm rather fond of toad in the hole. It's not that easy to find something suitable to cook it in especially in a combi oven. I started looking at pizza pans but couldn't find anything reasonably priced and over 12" dia. Some are often too shallow. I've also found the 12" pans are usually smaller and don't really contain enough for 3 generous portions. The coatings wear off rapidly too..

After several hours of web searching I came across a company called Ace Pans. Made in the UK. Given the prices I was a little dubious but ordered several anyway. They are available in either "iron" or aluminium so went for the later. These are far more substantial than I expected. The sizes also relate to the minimum diameter at the base. The sloping sides increase this by around 1". They are spun and they even have a rolled edge.

I ordered a 9", 13" and a 14". Unfortunately the 14" wont fit in the combi. They aren't coated. A plus as I see it. My mother used several similar but smaller pans for years and years without problem. They were probably bought pre WWII and were still in use a few years ago.

The 9" is destined to be fitted to a bird feeder to catch discarded seed. We have recently had problems with the mess pigeons leave while pecking up the bits that fall onto the patio. We had been feeding small birds via a feeder for a long long time. No problems with pigeons until a pair recently found the fallout to be an easy source of food.

The 9" size is deeper than the others. I suspect I will order a couple more. They should make a great pie dish.

John

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Thanks for that link. The COS sheet clears something up for me. That rigidisers are colloidal silica I had seen a comment that ceramic board lasts longer if treated with colloidal silica and wasn't sure if this was the same thing as the rigidisers.

John

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