Member postings for Ajohnw

The reason for the belt drive being more powerful is because that style of speed reduction actually increases torque so apart from losses in the drive power remains the same. Electronic speed control on either type of motor doesn't do that. Torque tends to be constant so actual power is reduced as the speed is slowed down. Some ac inverter drives model the heating effects of the motor so may actually drop the troque. This happens because the motors have a max current rating and running them more slowly doesn't mean that they can pass more current - less in practice because at some point they will overheat as the usual cooling fan is also running at a lower speed. Actually in principle it's better to speed them up but at some point the armature will burst due to centrifugal forces.

As Ketan of Arceuro mentioned it's hard to be sure about what the actual output power of variable speed machine tools really is. The ones he sells are rated on output power. Some may be rated on input power. Either might have power stated for a certain time limit. Some AC motors state continuous some don't.

John

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Edited By Ajohnw on 03/02/2016 17:56:07

It's the last version of the VSL. Big bore and a neat variable speed. Some have hardened beds.

I'd loose 2 cupboards and 2 draws and have to move a sink.

Nothing to do with me by the way. Just noticed in passing.

John

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Actually I don't think that an AC motor will produce much torque at 1500, 3000 rpm as mentioned for 50Hz. That's why circa 1400 and 2,800 are more usual and 3000 rpm off hand grinders wild claims. There needs to be some slip in practice.

John

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This is the sort of sale I feel people should look for when buying a lathe. A little down this page

**LINK**

Boxford VSL.

Be interesting to see how long it takes to sell. Often if there is a lot of kit people are inclined to think the price is a too high. Much depends on wear. I would want to know some of it's history and try it but other than I have to have a bench lathe I would be in for a long drive.

John

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if you get to the bottom of this subject neglecting things like permanent magnet motors you'll find that the sizes of an AC and a DC motor will be very similar if they run at the same speed and provide the same output power.

Essentially DC and universal motors can run at higher speeds so can be smaller for the same horse power output.

John

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A number of people seem to spend a lot of time improving their printers, Some are for ever printing things with them. Some often print spare parts for their printer - using what seems to be a biodegradable plastic.

I have a number of things that aren't used that often - they are things for specifics not daily use. A 3D printer would just be another one. I suspect I will buy a kit that from reading comments on the web about some models looks like it has a rigid frame.

Can't be used without software though and that aspect has proved interesting. I had no idea what went on with them other than a 3D cad package was needed but a free ebook I found cleared that up.

At the cad end I have tried SketchUp. Mixed feelings and probably buggy but some of that might be down to running it on Linux. It has it's oddities - pointers for doing things often shouldn't be put at the point where they are needed, more waved around in the general area and it will latch onto cardinal points of nearby objects. The eraser is particularly interesting. In some cases it needs rubbing around something for many seconds until it finds it.

As a test I've been playing with this

The L was made with typed in line lengths and extruded - no means of typing a length in for the extruder unless I missed it so it has to be carefully adjusted with the mouse. The initial scale was more like a kilometer across the screen so I drew a 100mm line and then found it. I added the fillet and ran into grief with the projection looking odd so move the axis and did it again. Ok this time. This seems to be down to not holding a key down while it was drawn to force assumed axis. You'd think it should be the other way round - press a key to free the axis. Initially I drew slots on the face and extruded them through it. One came out slanted, need to hold a key again. The other refused to select to allow it to be extruded for no apparent reason. All were drawn on the face. When it worked this did create a slot. I then though try the union operators. as per the photo. This time it wont recognise the actual plate as a solid so I suppose I need to group the lot or make it into a component. In one case it does assume a solid and in another doesn't.

When I created the fillet, all with on face lines entering a measurement on some wasn't a problem. The one across the base came up with a ~ in front of them indicating approx. Later the measurement was entered 1mm more than I wanted no problem adding the dimension. Strange.

I could have added some edge rads before extruding but wanted to leave them for later for a tougher test. Trying to select the edges they should follow has proved to be impossible so far. Surfaces no problem but adding a rad round one of those left a discontinuity. Maybe grouping or making into a component might help. There isn't a truly optimal command for creating rads for this purpose which makes things awkward anyway.

At start up there is an option that starts with a plan and by the look of it 4 views. Perhaps it's unfinished from google code days. I think it's just for floor plans.

Many moons ago when people dialled up to bulletin boards, no web, I was offered a cheap copy of 3D studio from Autodesk and spent a lot of time with it. SketchUp to me seems to be still hung up some what in that sort of area rather than precise sizes and mostly just has weaker but similar facilities. One neat facility that it's easy to miss is that the centre mouse button allows the view to be swung round while another command is active. The up and left right mouse button lock to the axis. There will be others tucked away - a problem that sort of info should be grouped in one place that's easy to find. I had to use the web. A help screen pops up when each command is used but it indicates that there may be more options.

John

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I didn't come across the free license aspect but eventually came across the prices - pretty sure that involved going to the USA site. I've just managed to find the less than $100K part and renew as required.

John

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I've managed to get Sketchup running on Linux. This link helped

**LINK**

One problem so far. Window going black when the draw a box style selection is used. With plugins it's surprising what this package can do - not looked at adding those yet but some useful ones are free. The app may have web links built in to get them and those may not work. Google like to know what people are doing and that is where this app came from.

Initially it looked like it was possible to start in 2D with the usual projections, ideal for some things but it didn't work. Might be down to me or it wont actually do it. Dimensioning parts as they are made isn't obvious and it starts up at a massive scale. At screen dpi something 200mm long comes out at thousands and thousands of them. There doesn't seem to be a way of setting initial scale.

I also looked at what Cubify Invent ( circa £30) could do via tutorials. A lot actually but one important aspect wasn't mentioned and seem to be skipped - some fillets etc can only be run via a 3d view after parts have been joined. I'd guess it isn't available. The video's were based on an early version. Sketchup does seem to do that. Only problem is that pro is downloaded and remains active for 30 days and then becomes Make. That happens when Make is downloaded as well - stupid advertising really. As if people who down load Make will spend £300 plus. Having to wait for 30 days to see what's left is irritating but I have seen what people have done with it. Some one called Gina on stargazersloungs posts all sorts. Gears, ratchets and many other bits and pieces.

John

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I find a lot of these posts interesting. I reckon I became immune to adverts where ever they were when I was around 15. A few did have an effect. For years now no effect at all. I might notice yet another iPhone has come out but buy another make and model. I'd guess many people are the same but the add industry in all areas is a money go round that could mostly be replaced by a search engine and on line stores.

Some fools pay for space on this site and many others which allows them to exist. Lets hope they never realise that the adds as presented are a waste of money and screen space. They could be replaced by simple links plus a note of what they sell.

John

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Interesting statistic on TV. When video recorders were popular the largest uptake on a household basis was the UK by a large margin. Thought to be down to the fact that we "did" get TV worth recording. All thought to be down to the BBC.Others had to compete.

Having tried to watch Swedish free TV I can see why but then the BBC is cheap really rather than free.

Interesting comment from some American TV person. "Once Brit's went to the USA for ideas for cheap TV, now it's often the other way round"

John

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Their trucks do have a certain amount of presence.

I drove one of these several times around 15 or so years ago. Brand new and very similar. The only truck I have ever been in where the passenger seat seemed to be an extra. Some sort of steel box instead. It had the worst gear box I have ever used. Clutch travel was enormous too. All in all the only good thing was the air suspension and the looks but it still needed air suspended seats.

John

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I mentioned a type of square to Brian at some point. It and maybe a larger conventional engineers square is all that may be needed really plus a protractor. It looked like China had missed the squares as I could find them by a main manufacturer at a very steep price Chronos have had them though

**LINK**

Usually the only measuring blade is the narrow one.

Stock number SS125. Odd that there aren't many used ones about as they were very common in toolmakers chests. A bit of a must have.

John

You can more or less forget drilling it out Brian. A carbide drill might do it but would probably snap. You could try drilling down the flutes with something in a Dremel but if it tries to remove material from the tap you will probably finish up with something else stuck in it. The perfect answer is spark erosion.

Looking at the photo I would have thought a decent quality pair of 8 or 9" engineers pliers would get it out. Mole grips too as pgk suggested. Try and find a old major brand name.

Tapping M2 is not like M6. It needs more care, tap square and more frequent reversals to break the chip.

Usual reasons for breaks.

Tap not square to hole - I suggested that you should check to see how square your drilling machine is to the table and adjust if needed - a large 300mm adjustable spanner will undo the nut. They can usually be bought in sets of 3.

Not reversing often enough. People are inclined to never do that often enough and get away with it until the try very small sizes. It's obvious really. Think about the width of the flutes and how much of a turn is needed before the chip has to bend. The tap will bend the chip but it's easy to ask it to bend too much.

Wrong sized hole - check the sizes of drills. Don't assume that they will be correct at small sizes. Brass tends to cut very cleanly so this may well be your problem. Taps at this size shouldn't take much effort. If you measured a 1.7 rather than 1.6 you might find it's 1.65 so that would be the one to use unless the 1.6mm was definitely 1.6 dia or slightly larger. You'll probably find it's undersized. They usually are.

Here is a source of engineering tools for you

**LINK**

Those pliers are ajohn approved but sadly lack the notch in the side for cutting thick wire.

If you want to get some locking pliers the rs pro ones should be ok

**LINK**

Their adjustable spanners are a bit expensive. As a company they tend to sell high end and ok stuff and no junk. They did sell Chinese lathes at one point but dropped them - too many complaints.

I use a set of ones that are similar to these also the plain ones without plastic on the handle. The main thing is the material they are made of

**LINK**

John

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Fusion seems to be licensed on a by the month or for a month when needed basis. Perpetual licenses available for a short period that I think ends today.

Maybe I have missed something. It seems Sketchup can be free.

John

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Thanks Jason. Cubify looks promising - not too bad an expense for yet another toy. I might be able to run it on Linux too via wine as it will even run on Vista. Just might but it can be downloaded and tried first.

There is one called OpenSCAD. It's driven by words rather than by drawing on the screen.

I wonder what others there are.

John

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Edited By Ajohnw on 31/01/2016 20:22:16

I've wondered about buying a 3D printer but haven't had much luck finding out what cad software to use with it.

Ideally it needs to be able to do gears or what ever. Sketchup is used by one person I am aware of but the license cost is more than I am likely to spend on a machine. I've also seen comments that it's free but needs a plugin in order to produce the correct files for the printer.

So what is available and what can it do? Any one any ideas. The web seems to be thin on the ground on this subject. Cheap machines and expensive software. Some artist type software about but not for what might be called engineering. There also seems to be some rather torturous routes using software that was really intended for other purposes.

Oh - I'd like to run it all on Linux but could manage windows if I must.

John

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Edited By Ajohnw on 31/01/2016 18:40:53

I would suggest that you leave the head attached to the bed. If like the ones I have seen and owned there will also be some grub screws going in from the side - great fun to set so best left alone. I have had web conversations with people who reckon it's impossible to align the head again after it's removed. Also many that find it very difficult to reset the bearings. I usually suggest replacing the rear races with mixed feelings as it might not help them due to wear in the front cone. In some ways it might be better to leave well enough alone and only fix if it needs fixing. The 1st thing to try is bearing adjustment if that seems to be needed.

John

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I'd try a centre drill if I were you Brian. They are designed for the job and don't flex at all. They needn't be exactly on centre either as they are capable of cutting on one side which will generate a true start for the drill to centre on when it's used.

It is best to cut at least a slight cone but taking a No 4 the tip is only slightly over 3mm dia., a No 3 slightly less. Your unlikely to break either size. I use a No4 most of the time and a No2 if I need to for some reason. Both sizes are pretty robust. If some one's tail stock is well out they may have problems with a number 2. I don't feed these as quickly as a drill but they do need to cut and not just rub especially on aluminium.

If you buy more spotting drills look for HSE or M35. Frankly I can't see the point of them as wonderful as they are,

I also have some No1's or 0's. A bit fine for a boxford really as they would ideally need a higher speed than it can give but the correct feed rate will look after that.

John

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If it comes down to discussions about truth surely politicians take the biscuit for miss leading adverts and statements of one sort or another - yet no one prosecutes them. I'm sure if an add agency was miss leading to a similar degree they might get prosecuted but that gets less and less likely day by day.

John

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Many of the things mentioned are related to everything being dumbed down. I often wonder what IQ these people assume abounds in the general population. Clearly we all must be much thicker than a typical plank even an extremely strong one.

That's not being fair really. The fact is that stupid statements probably boost sales a little bit and that is all they care about really and don't care if it causes some people irritation. All they are really intended to do is to get people to look at what ever it is.

The UK's usual buy 2 get one free really means over priced or short dated / too much stock and not selling quickly enough. Our local co op has a new manager that has started doing that with all sorts of things.

I've found caller id is the best way to avoid answering nuisance phone calls. Near 100% of them come up out of area or with some none existent std codes. If we get it wrong there is an answer phone. I have been known to set that so that it answers after 2 rings in rather painful periods - claiming loan repayment insurance refunds hitting the heights for instance.

John

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Edited By Ajohnw on 31/01/2016 16:32:06