Member postings for Ajohnw

A few posts down below this one

**LINK**

John

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I think some of the metric mini lathes come with 2, Amadeal (harry something or the other on ebay or his web site) or a name something like that. It seems many don't come with one.

It's good to see a site that explains how they work. Another way of putting it is that the indicator marks give repeat distances of the lead screw that are exactly divisible by the pitch being cut.

John

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Edited By John W1 on 08/11/2015 23:42:40

So close that they may not come apart going on some of my chucks.

What I usually do is remove the jaws and flick the bits out with a brush and rotate the scroll and flick some more etc. It's usually possible to get all of the bits out that way with the chuck on it's edge.

That white stuff removed in the link is probably lithium grease. If it has been there from new it's probably best left in place or replaced. I've not needed to dismantle my grip trues but going on the link it looks to be relatively easy.

John

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Ours was built in 1911 and way too many draughts to even think about doing anything about it. Anyway a certain regular amount of fresh air is desirable in my view.

John

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This house is a "bit" bigger than a semi as it has 3 floors. The area of each floor is bigger than a typical semi. Some space is waisted by having a rather large hall. We just had the october to october gas figure £1300. A bit less than last year, maybe because I flushed the system backwards and did one or two other things. There are a number of reasons why few of the windows are double glaze, mainly stone mullions on the front. As I mention solid brick walls. Now we are retired the house has to be heated as required.

The first pump lasted a long long time, replacements didn't. The original make and type wasn't available any more when it went. From my experiences with them I would say that typical life time gets less and less as time goes on but the pump has a hard time heating the heat store so that's where problems show up as the flow rate drops off due to wear.

The systems I have seen that don't have a Y plan or what ever valve usually use convectional flow to heat the hot water and a pump to get water through the radiators so all the heating controls do is run the pump when central heating is needed.

John

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They upgraded the disk springs on the later machines Hopper. There is a fair stack of them so small changes in distances don't have much effect on the loading the springs give. I've wondered if I could graft something into my boxford but don't know how well it would work out on a more powerful machine and there isn't enough extra length on the spindle to do anything sensible anyway. I was on the yahoo unimat group for some time and no complaints about bearings there. Really when they are used like this there isn't much difference to angular contact other than contact angle. I've no idea about that aspect. Maybe they wont last so long, maybe they will. I do associated disc springs with relatively low power stuff though but that's gut feeling really.

I ran a used Toyota Celica for 12 months or so when people laughed at Japanese cars. One review I had seen in a fringe car tuning mag went through the model pretty thoroughly and were impressed. I had a Triumph Stag and strange engine noises so needed something quick. All in all it was a pretty impressive car and I ran it for longer than intended. Price wise it was pretty amazing. My wife to be turned up her nose but changed her mind after being run around in it as did several friends. Later as we ran a 4x4 I bought another one. Not with the 4 valve per cylinder high reving drop forged piston engine one of my cousins who worked at Holbay worked on but a more moderate version. An outstanding car, it drove and even sounded and felt just as Brit sports cars should. I later found out that they had been talking to Lotus. It did feel a bit like one, I have owned a couple and there is something distinctive about cars Chapman passed off. I changed the plugs on it. The engine ran a little rough while the electronics sorted itself out to match them. LOL People talk about .de attention to detail. At this time they started including goodies for free, some were gimmicks some not.

I have some "jap junk" microscopes. They knocked them out at around 1/2 the price of the west. Optics very similar some makes worse some better. They didn't last as long mechanically but in real terms lasted more than long enough.

I suspect this bloke had a lot to do with there success but there is a need to read up on his philosophy and also some examples of what it achieved in real world results - essentially a quality feel / look often at lower cost,

**LINK**

They also largely due to lack of space had some interesting ideas concerning running factories and supplies. Used the world over now. Other interesting aspects as well - what to do if production gets behind. The supplies keep coming so you stack them in the corridors or where ever as it encourages people to speed up. That one goes way back.

It's not QC Brian it's how they choose to make them. I suspect a lot of what Hopper found on the saddle fit was casting distortion following machining. I suppose they could leave the parts in the moulds longer to cool more slowly = more moulds needed and then leave them lying around for a couple of years before doing anything with them = a lot more unpaid for stock but once machined with a casting of that shape they would probably still need to machine them again to do anything about it. Start checking them = slow and many would be rejected. This is why they are so variable. People are well aware that they are buying unground parts that fit together and really should be ground but in real terms it isn't just as simple as that.

Company balance sheets are very much look after the pennies and the pounds look after themselves.

Cars - I tried a couple of Kia's before buying my current car. All I can say on that score is watch out manufacturers. Other make retailers though are still trying to treat them as disposable cars - worthless once they have had one owner. They never have been that bad really only a bit rustic, before Hyundai got hold of them.

Hyundai make lathes and all sorts of things but not much use to Brian. Me well I have been running Korean tyres for some time. Fitted as OE on some makes now.

John

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Edited By John W1 on 08/11/2015 16:08:41

There is a similar night storage system available in the UK Ian. This house had it in when we moved in. Gas worked out a lot cheaper when it was installed. Not sure how it compares now and the storage heater have improved as well. Some of the ones here were just a water tank but the electric people provided a cheap top up sometime around mid day. It was probably installed in the 60's maybe 70's.

I put the gas heating in about 20 years ago and at that time most people were installing 80 - 60C systems as mentioned in the link I posted. Microbore was having problems due to the people installing them hence having to do 10mm myself but with a length limit due to the size of the radiators needed for 60C running. The 80C types would only really be need to be run at that when it was very cold but that's when the heating spends a lot of time on. The last paragraph in the link explains the problem. Insulate the house so that the 80C rad temperature isn't needed at all and things get different. Change radiator sizes and different again. On new builds now it's all well sorted out. Live in a 3 story 5 bed solid wall house like I do and things aren't so easy but fortunately the radiators are big enough to make good use of a condensing boiler. No hot water tanks and a vented system to make replacement difficult. Solid floors and some odd pipe runs so a sealed system might have problems without some rather large expansion vessels. We use a heat store for hot water so there is no run up time as there is with combi's. The boiler hardly ever comes on to keep the store up to temperature so I'm not keen to change that aspect. We don't have any heating on the top floor. The roof is insulated and the lower floors keep it warm.

We ran it with no thermostat for a long time, unusual at the time and just used the radiator valves. Pump life suffers though so eventually I fitted a thermostat. Never been happy were it was really - in the room with the boiler uncontrolled over run radiator so just bought one with a radio link from the thermostat to the controller so I can move it around. Currently in the living room along with 2 rads with wax stats. This is a don't do but the results so far look like they will be of some benefit to the gas bill. The over run radiator is in one of the bathrooms so guess that might get a little bit warmer than needed - so what.

John

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Edited By John W1 on 08/11/2015 12:12:11

Perhaps you should phone up who ever makes Unimats and tell them to stop doing it then Ketan. Doubt if they will take much notice, owners or sellers of replacement bearing either. Oddly enough they are very precise lathes. Weird that isn't it.

Sorry but I get cheesed of by no you can't when you most definitely can people.

John

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That's what I was inferring earlier also that prices are artificially high because people are "saving money" or so they say which in many cases they wont be considering how long it takes to recoup the cost. It also gets less attractive as people age. There comes a point in life where people are unlikely to ever recoup the cost.

Condensing boilers don't work out too well when installed on older systems either as they generally don't have sufficient radiator area. To make best use of them systems need designing from scratch specifically to suit this style of boiler so that it can actually condense. There is a bit about that here

**LINK**

The problem is that prior to this style of boiler being used the design temperatures were too high and a lot more radiator area is needed to make good use of them.

John

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Martin I understand some without much space have gone for a bore hole but no idea how deep or costs.

They use solar water heating in Turkey, extensively. Just a barrel on the roof and pipes sized to allow convection to circulate the water.

John

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Ground source heating aught to be the cheapest option really. Bore hole / buried pipe networks and a freezer sort of arrangement which gives some idea what the gear would cost if some one really got down to making it in volume.

This touches on the problems with "green technologies". Subsidies aimed at helping with start up costs with larger items in real terms tends to attract people who say hey I can make some money with this and don't really do anything useful in terms of getting costs down and just moan when the subsidies go.

The other problem for consumers is pay back time. That can be rather surprising if some one takes the time to work it out. I looked at converting a car to lpg once. Bit of a joke cost wise but at the time that may have been down to every man and his dog becoming conversion specialists. People can also buy things for a few hundred quid that are pretty dubious. I was always fascinated by ebay sellers offering certain motors for home made wind "turbines". Even B&Q sold something that might keep a light on but not much else at that sort of price. Then there were people making and selling units which extracted heat from the outside air - heat pumps aka freezers again.

On the plus side though when central heating was installed in our house - it was on economy seven. I wasn't at all happy with the plumbers that came and looked so did the sums myself. Also had the gas people in and the surveyor happened to see my sums when he was looking around. He told me he had come up with the same numbers. Still not happy and had come across some flow rates and radiator heating information through 10mm pipes. For a certain size of radiator there is a max pipe length related to bore. No one would do this so did that myself. Plumbers came up with crazy boiler prices so went and bought one myself and then got some one in to finish off. Most of the info came from some one that was determined to get some science into central heating and they made some interesting claims about radiator valves so I fitted those when I installed the radiators. Radiators sized on the basis of efficiency from the science man, they run cooler than what was usual at that time. The boiler has an in built heat store. The idea being that a bath can be run, water will cool but not go cold and 4min later another bath can be run. It runs full whack to heat the water and around 1/2 power for heating. Sums suggested that heating would need to be turned up to near full whack. It never has been and we haven't been cold - thanks to simple wax stats on the radiators. The boiler will be replaced soon so has to be a condensing boiler. Thanks to the radiator sizing that will be far more beneficial to us than it will be to many people having them fitted as a replacement for an older boiler. Biggest problem is the heat store. The manufacturers tell me we want one that is truly very much larger than the one we have been using which means that it will take a lot lot longer to heat up if it cools. The house is generally considered to be too big for a combi. Hot water was supplied by 2 powerful gas instant water heaters when it was on economy seven.

Light bulbs - for much of the year in the UK filament bulbs produce useful heat when they are on a lot. The heat has to come from somewhere.

Street lighting - became a lot more widespread when electricity companies offered electricity for them cheaply as much of the time they are on during off peak periods. Some councils fit high cri led lighting. These are less efficient than low pressure sodium. When ever the lighting is changed it always provides higher light levels as well.

Green ? makes one wonder. More like an opportunity to rip the general public off.

John

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Emco have been using ordinary ball races in an angular contact fashion on unimats for donkeys years Hopper. They use disk springs to force the inners against the outers and if used for some time and the bearings are replaced the inners really are very loose in the outers. When I had one I replaced them. No need to really but the idea works well. The disk springs of course improve things further over a simple nut to set the preload. So the bearing man's idea does make sense - higher balls = bigger contact area. I was going to use the same idea on a toolpost grinder as it can work so well but for various reasons have decided plain bearings are a better option for what I want.

Seems it was pointless explaining why costs aren't so simple as people might think Brian but continue to believe what you believe if you want. Fact China has factories that can produce many things to what ever standard a customer wants - at a price just like any where else. Fact toolmaking a while ago now - China costs 7 1/2 % lower than the USA. To do that sort of thing they need the same level of equipment, skill etc as the west uses. I mean real toolmaking.

One of the what might seem odd aspects about manufacture is that profit margins are usually low so if the costs there go up by a few quid it will be a lot more by the time it gets to you. Actually I think you would be gob smacked by how much your lathe actually costed to make. A lot less than you might be inclined to think.

John

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It doesn't matter how big a persons kit is jacks are sometimes needed. It all depends on the part. Personally for support I'd like to see a lock nut nut but if I didn't happen to have one ......................

John

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It would be nice to hear truly unbiased facts about all energy sectors Chris. Unlikely to ever happen.

However I did hear one once idly watching the box. The 2 founders of Green Peace apologising for campaigning against nuclear early on. They reckoned an absolutely enormous amount of coal has been burnt as a result. They had finally realised that people need power so their is a need to be realistic. What ever is done has it's problems.

Another but from a newspaper so dubious as always. People being phoned up and asked to start generating electricity from north sea products. Don't worry about costs you'll get a cheap loan. My impression was from gas but may be oil or a mix. Rather a waste cost wise from the UK's populations point of view. It would be better used purely for what oil and gas are primarily used for in the UK to save on imports and keep costs down. Short termism instead. I actually tried to research this once but got no where. Paper - Sunday Times. We import gas now, it comes in via ships. Not sure how true this is but some one who was involved in the pipework needed reckoned it will last circa 30 years. No more Victorian engineering these days.

Many moons ago what was probably a truthful statement. If the UK doesn't build a nuclear power station now and again we will loose the skills. Also that they have to be replaced at some point.

Meanwhile while this has been going on Sweden circa 50% nuclear, France much much higher. Germany was similar to the UK, many protests about nuclear there. Sweden I understand is switching to biofuel but they have circa 50% hydro.

Maybe the UK should have gone very nuclear and later started phasing it out but in real terms given the amount of it that is about should it be totally phased out. Much of the reasons for doing that are mostly down to a few instances that in real terms are circumstantial. All we will get is the yah boo from the various sectors rather than facts.

John

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Rotate a boring tool so that it can go down a smaller hole with neg rake.

When tipped boring tool holders are bought the usually specify a min hole diameter that will be larger than the shank.Sometimes the difference is a lot, sometimes it's not eg

**LINK**

In fact the clearance needed on them over the bar size isn't all that great on any of the internal threading insert holders. Or the normal boring tool holders. They do it by having a larger diameter off set end to maintain strength.

Maybe get the end red hot and hit it with a hammer etc,

John

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There was some one on ebay selling those some time ago. I enquired about more pitches. None available. They said these are the iso standards ??????

John

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The sums are no different to cutting an ordinary gear but there is a catch I'll come to.

You can convert dp or mod to a circular pitch or the other way round. There are calculators about on the web so pick a worm pitch which I would suggest wants to be ideally bigger than 1/10" or 3mm especially for a rotary table convert to dp or mod and use the calculators to work out the OD etc. The gear pressure angle needs to match the "acme" angle of the worm as it's effectively behaving like a rack does and clearance as far as the gear is concerned might best be set to zero.

There is a chart in my album that converts between cp, dp and mod.

One catch that is sometimes mentioned is that the tooth count only matches the OD of the worm wheel when the "tap" that is used to make it is at full depth. So some suggest feeding it in as quickly as you can at each rev of the wheel.

Another is that the worm and wheel need to mate on the flanks so effectively the worm needs to be a some what smaller dia than the tap and be cut a little deeper to make sure that there is clearance and that they do just mesh on the flanks and that the tips and roots clear each other. It's probably easier to do it this way rather than mess with the cutting of the gear.

I'm not sure if making the rim of the worm wheel narrow helps cutting them or not. There's certainly less cutting required for for full depth teeth and having a bit more width with slowly vanishing depth wont increase the strength by much.

Cost. Fabricated way less than a kit or bought far eastern items. It might pay to remember that with a bit of care people have made things like this to the same sort of standards as items costing way way more than what model engineers generally buy.

There is one catch with putting the worm in a carrier like that rotary table. The dividing head uses one as well. The way it's done is to bore and ream always using the same reamer. Then fit a shaft by hand to carry it and pass through the bearings at each end of the carrier. It needs to be a firmish hand push fit. More or less zero clearance. On the kits the carrier would be cast iron which wont bind on a mild steel shaft. It might pay to make the carrier out of bronze instead or at least bush it. The shaft needs a centre hole in the end so that end play can be adjusted via a grub screw with a point on the end and a lock nut.

Too many ends.

Out of interest this is the dividing head with the 40T wheel on. Usual sector arms and plunger on the other side.

John

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Making the worm wheel seems to be a pretty straight forwards task providing it's gashed first. If not it's hard to guarantee the correct number of teeth come out. Some people have used an acme tap rather than 2 worms and gashing and hardening one of them. Other people's experience rather than mine.

My miller came with a dividing head with a couple of worm wheels that were home made. There is no back lash at all in it. One of the interesting aspect is that who ever made them kept the rim relatively narrow. The teeth are about 5mm wide tapering onto a rim round the wheel which is 7mm wide.The wheel is a 60T and the od 62.3mm. Not really big enough for a rotary table. I'd guess the cp is about 3mm probably 1/8". The worm is 15.9mm dia 5/8" dia. This isn't how most people make them. The rim of the wheel is usually a lot wider in relation to the worm dia. As the same thing has been done on the quill feed on the miller I wonder if this is the best way to go and easier to cut well with a tap. I think this head design was down to Dore or Westbury.

He also made a rotary table. On that the wheel rim is a lot thicker but also a lot bigger, the dia is something like 80mm. Pitch around 3/16". It's a 60T wheel. The arrangement on this one is interesting.

Zero shift table locking by using a cam to press the worm against the wheel. It's not something I have used much but it seems to work. The worm has to be supported a both.ends to do that. The worm is held in contact with the wheel by the spring so any slight run out is accounted for = zero backlash but I haven't checked that precisely. It aught to be because each time it's locked the worm is forced firmly into the wheel. I think this design is down to Dore Westbury as well. Could be either of them.

Come with a warning though. When I bought it the cam action wouldn't fully clear the worm from the wheel, It just touched. Not sure why. The casting might have distorted over time. So I removed the brass strap and worm plus carrier and milled a little bit more relief behind the cam bracket. 1/2 hr late the casting crack there. Most likely down to removing the strap. Just show's how much stress had been left in the casting by the supplier. This doesn't interfere with it in use. Many people reckoned that it was better to fabricate rather than buy castings especially for tooling as stress problems weren't that unusual.

It was made by Hugh Simmonds in 1988. There is a little brass plate. The same name and date is on the miller Nothing on the dividing head so I would guess the table was the first thing he made on the miller. All of the work is to a pretty high standard. That's what persuaded me to buy the miller. The "new" owner of that couldn't get on with it. Settings, crap vice and blunt cutters. Plus no clue at all I suspect.

John

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That's what I expected Phil but having looked at a number of them at the model engineering exhibition none would allow it to be fully taken out. Some sort of stop inside. Suggests that Neil's wind back 1/2 turn and then to the sector arm is a must.

There was model engineer design about that use a spring to tension the worm against the wheel. It also uses worm pressure via a cam to lock it. Not too keen on that but the spring idea seems sound.

John

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As the depth is correct on all it sounds like a back lash problem to me or the index fingers loosing their spacing if really bad.

I did look at various rotary thingies at the recent model engineering exhibition and wasn't impressed with degree of backlash on the ones that could be tried. In fact the adjustments were limited so that it was impossible to check if there were tight spots and how bad these might be.

I'm not at all sure how some one could check that the back lash is still taken up when the clamp is released ready to move to the next index so over to some one else.

John

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