Member postings for Ajohnw

That's a thought. I have found another company that just sells air fittings. I don't think that there will be any problem using them but if there is I could use those people but not that pleasant a drive to them.

The problem I have with the fittings on the few air tools I have is that some one makes a coupling that will work with all of the variations. Or should but a better option seems to be to switch to one where all makes seem to be interchangeable. I would probably picked euro but can't see a 1/8 bsp fitting for it. I need that to make changing the welder over from air for plasma to argon for tig easy. All I need do is saw some of the pipe tail end on it off as it leaves plenty of 1/8 bsp thread for an adapter.

They hold the internal gas valve in place with the tail end plus a lock nut. The tail end is a bit of a let down compared with the rest of it - it needs clips to hold the pipe on. They provide a couple.

John

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I think the drive wheels are a little too close together for it's capacity and it's important to tension the blade enough to make sure it's vertical to the cut.

Would I be happy if I had bought a Femi - no because I have used it to cut material that the femi wont take several times. In fact I have had to turn bar over to cut completely through it at times.

Personally if some one is thinking about buying one and the size isn't a problem I would think long and hard about that aspect.

On price didn't Neil mention that the cheaper version of the Machine Mart and probably the Axminster one is more flimsy ?

The biggest problem with them as I see it is the size of the chunk of material needed in the vice. That could be a useful mod.

John

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Edited By Ajohnw on 04/01/2017 23:54:04

What I noticed on mine is that the blade wandered and then tended to come off because it was cutting at an unnatural angle. So I just tightened the blade. Some time later it did the same thing again as it was wandering about again. I suspect much of this was down initially to the leverage being a bit on the low side - needs a bigger handle and blade stretch later.

It also pays to set the guide sensibly. No need to have them wide open unless the stock needs it. I'd say where I usually have those would  take 3" dia stock. Maybe 4.

The wheels are still on mine but it doesn't get moved very often. If I was doing the sort of thing Ian does with his I'd buy some adjustable height rollers to take the weight. For my usual 2ft max lengths the legs have been find and anything else such as angle iron which has been longer I find something to support the stock or just hold it square to the machine while I'm closing the vice. I set that up square to the blade.

John

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Edited By Ajohnw on 04/01/2017 20:19:43

It's possible to buy tail ends for flexible pipe for a variety of bore tubing and bsp fittings. Then there are several types of clip to hold the pipe on the tail end.

When I've looked at flexible pipe the bore size has always been clearly stated as that's what matters for flow. The compressor line I've bought said 8mm so expected 8mm bore. It's 8mm od. The end fittings are 1/4 bsp but several sizes can be used there for pipe in this size range.

I went for 6mm flexible as argon will be at around 7l/min. Air about 100l/m but only for maybe 2ft. The airline to the compressor is 5m long. I doubt if this will mater but I'm dam sure it wouldn't if it had an 8mm bore.

John

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I just read the details of the air needed from a similar dedicated plasma cutting machine. This one for instance which is a 30amp unit. The one I looked at was 25amps max. There isn't much difference.

**LINK**

It's turned out to be an expensive add on (for my wife) for what I want which was just tig and stick. Being fair about that though buying Xmas presents for me is always a problem and if needed I'm pretty sure I can boost it up by fitting something like a Clarke 2hp twin cylinder pump head. These go on Clarke's industrial blue range.

As some one mentioned in the 3in1 thread it's duty cycle isn't terribly good but I will probably set it up with the regulator on the compressor set at 5 or 6 bar and the one on the unit at circa 50psi. The compressor cuts back in at 8 bar. Might be ok. Depends on how long the torch needs to be on.

It's a hell of a spec for this type of compressor - this one is similar

**LINK**

I spent some time on that site looking to see what could be expected from different sizes of compressor. There are various versions of the one I bought though and numbers differ. Einhill do give a number which is unusual so decided to give it a go,

Use - I might do an engine Jason style some day and being able to profile plate would be useful. Also other things. The idea of clean cut is immediately suitable for welding. The deeper figure they give isn't. It seems that the way to use them is to move the torch at a rate that causes narrow angle sparks to come out of the back. Too slow and the angle will widen. Add the torch needing to be about 1mm from the work I wonder why they don't all come with a guide to space the torch off the work. I'm thinking about something based on a pipe clip. Simple as making anything at the moment is a bit difficult.

John

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Edited By Ajohnw on 04/01/2017 19:40:03

And Neil still hasn't put a huge link up that explains what levelling means in lathe terms.

I just don't mount them firmly just finger tight and set the jack screws by hand so I can be pretty sure that all 4 are just supporting the bed. I've added rubber washers on some lathes - no point. All the fixing need do is prevent the lathe from tipping over and also from vibrating too much.

Most lathes could be changed to 3 point mounting. Couple of spacers the same thickness as a plate to fix to the feet with a hole to provide the 3rd point.

John

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I'm not so sure as neither lathe I have had with this style of bed has had this problem. The raglan wasn't that sensitive to to gib adjustment. The ML7 was. Tightening everything up for some drag improved it a lot. No repetitive rings on either.

I've since found that slideway oil can help as well. It probably helps reduce clearances and also tends to hang around for some time.

Interesting to here mention of Atlas. Not popular for some reason so often cheap. An owner of a 10" described it as a Myford on steroids and the bearings can be changed. Not sure if that is true on all of them but he did get excellent work out of it.

John

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My small one came from B&Q years ago. The Einhell has a 50L tank but it stands on end. Part of the attraction as it takes up less floor space.

This page shows them all

**LINK**

This the one I just bought - or my wife did for xmas.

**LINK**

Looking at what some other plasma cutters need that one might do it. I don't think my small one would produce anywhere near enough air. 100l/min at 4 bar may be a touch too much but hardly any margin at all.

What I don't know yet is if it will actually do it or how long it will last etc. As wife bought it for me I'll have to sort it out if it falls short. I've never bought this brand name before but have noticed that some of the larger sellers have offered it in the past. Screwfix and Toolstation and others I think.

John

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A photo would help. Best lit with some reflection to give some idea of the degree.

The fact that they match the leadscrew pitch is rather unusual - in my view. It suggests movement on each revolution of the leadscrew. Larger work may provide more load and prevent it from happening. It really and truly isn't unusual for machines to produce different results due to cutting loads.

I think I would be inclined to look at the saddle fit as well. Also check somehow that the leadscrew isn't angled to the bed. It could be running true but if the bearings are miss positioned it wont be true to the bed. A tighter saddle fit might mask that problem. If it's a severe problem with the leadscrew you might be able to detect it by using the handle with the drive to the leadscrew disengaged.

From my memory the spindle pulley set up on a Myford is cast iron. Vibrations there could cause problems but not ones that match the leadscrew. I can't see how they could anyway.

If the work is bending running the same cut again usually shows that is happening but make sure that there is sufficient feed on before it takes the 2nd cut. Saddle fit can make the tool move away from the work when the saddle is wound back.

A travelling steady set perfectly more or less takes the rest of the lathe out of the equation. A principle much used on production capstan and auto lathes. Everything on them can move all over the place on these when the work gets into the cutter box and they still produce perfect results - usually with a rather heavy cut. I was gob smacked when I saw just how bad the rest of the machine could be.

John

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Super 7's have been know to produce immaculate finishes Michael. Truly amazing ones. The better it gets the more apparent very minor defects can be.

I've also got a shot of the same piece of silver steel turned without giving the bearings chance to warm up. It just about shows some rings down to the bearings and material / feed variations but most likely material.

The pattern isn't so marked and the light reflections show that the finish is worse. Increasing the feed rate may have given a better finish.

I did this following buying some of those finishing tips I have mentioned. Oil would probably help with the marginal tearing.

Suppose I should mention something about me. I have used machines that can produce perfect results with a sensible tool on them on any material within reason. Trouble is when new they probably costed more than many people houses. Having used them I want my machine at home to do the same. Next escapade for me is hss grinding as a careful look tells me that for some reason they are not as sharp as the ones I ground at work.

And so it goes on. Sort of challenge really.

John

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Edited By Ajohnw on 04/01/2017 12:31:36

I have an example of what vibration can do. This is what happens when my boxford bearings have warmed up.

It's silver steel and no doubt some will think what a crap finish but it isn't. It feels like glass and the shot is larger than life size.

There is a vague repeat pattern. I reckon it's caused by a wobble on my countershaft pulley. It's a pretty big one on an ME10 and it has about 1/16" + wobble. The same cut was run twice to get this but all the 2nd cut did was take a tiny amount of the end and make the pattern a little clearer. The cut was also pretty light. The effect on the end is probably down to the feed rate changing a touch as play is taken up.

What's being seen in the shot is features that probably aren't even 1 um deep. The same sort of thing can happen due to changes in the hardness of the material that is being turned. That usually produces rings that are obvious and spaced further apart and usually down to headstock bearings being past their ultimate best.Heavier cuts or a faster feed usually get rid of those.

The problem really apart from wear is that the tiniest deflection of the work or the tool can show. This is why on some lathes heavier cuts can help. The cutting forces produce enough deflection to make any other causes too small to show so well.

John

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As Michael points out that could be important.

John

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Adding to Michael's question - what depth of cut when this happens ?

First thing I would wonder about is if it disappears on deeper cuts or moderately faster feed rates.

One obvious thing to check is a warped leadscrew but I'd expect that to only cause problems on shallow cuts with a rather fine feed.

John

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I looked around at compressors before buying the Einhell one and asked why 2,800rpm motors. Not sure he said but think it's due to the stop start running. I wonder if it was just cost. Seems not.

If I do finish up putting another pump on the Einhell I would have been inclined to fit 4 pole.

John

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I've never looked at single phase motor specs before. Turns out to be interesting. Have to compare 2hp motors as there are footnotes on the 4 pole 3hp one. These are for capacitor start, capacitor run

Full load running current 9 amps and 8.7 amps ---- that's 2 pole then 4 pole rest will be too

Full load torque 5.01nm and 10nm ----- so about what would be expected

Starting torque ratio 2.5 and 2 ------ that's times the full load torque

Starting current ratio 5.75 and 5.1 ----- that's times the full load running current.

Efficiency 78 to 79.5% and 76 to 80% ---- They quote power factor figures against these the 4 pole low figure is better.

So it looks like 2 pole win out on stall torque to me. 25% increase for bit more than a 10% increase in current. Both 2hp ones seem to use size 90 frames. At 3HP the 4 pole switches to a 100 but the 2 pole is still in a 90. The running current of the 4 pole is 15 amps though rather than 13.2 for the 3HP 2 pole one. The 2 pole is also more efficient in 3HP.

Wow. I bet your all wanted to know this.

John

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That;s what struck me about 3hp bodge, A lot used to reckon that a 3hp lathe motor couldn't be run on a 3 pin plug. I did have one. Some one had fitted a 3hp to it so that he could turn certain tool steels. It was a Viceroy. I'd guess that the belt drive just wouldn't transmit that much really. It didn't blow fuses though even though the full load current draw is usually about 13 amps so start up could be a lot higher.

There used to be a 110v plug used in factories. The earth prong on the usual 3 pin was turned through 90 degrees. I understand some people used the 15amp fuse from those.

It was mostly many of the oil free that looked disgusting. They probably work because the air pressure tends to keep the piston square in the bore. The ones with oil vary.

I do wonder if one of 2 pole or 4 pole is more efficient or a different starting torque characteristic etc. I suspect it's just min cost. Many have a large pulley on the pump. Why not make it smaller as it would be cheaper. Leaving it the same size and increasing the other would cost more. The size of the big pulley might be needed to give the power transmission that's needed.

John

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I'd forgot the unloader Jason. Even the Einhell has one. Doesn't have much to do with 2 or 4 pole though. The unloader means that there must be some rotation before it sees any load.

Don't think Neil's reason is on either. They rate motors for a given temperature range which really means temperature rise when in use so probably less copper in the 2,800 rpm ones. Cost again.

No Nick if needed I'll change the pump head - also depending on replacement cost when and if the pump head wears out. A look round youtube shows just how disgusting the innards of some compressors are.

If it's not done for cost reasons then it needs to be electrical.

John

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That's what crops up on the web a lot. It doesn't really matter on the face of it when the final speed is much lower than both and the power at that speed the same.

John

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Not sure why I started nosing around on this subject but it probably relates to buying a compressor and looking at what is sold. In some ways use on compressors is most interesting as the motor starts on a high load not far off it's max. Other things are also regarded as having a high start up torque requirement but these must be one of the worst.

Most of them seem to be fitted with 2,800rpm cap start, cap run. Leaves me wondering if this is just due to cost difference over 1400 rpm. As they are speed reduced by a belt drive the motor could be either type even with the rather large pulley that goes on the pump. That may be there on some to serve as a flywheel and also a fan in some cases.

However there may be other reasons. 3HP seems to be a popular motor size. I would have thought this would stand a fair chance of blowing a 13 amp fuse in a 3 pin plug on start up but maybe the 2 pole motors help but I would have thought 4 pole would be better in all respects.

Most info on the web gets wrapped up in torque differences when what actually matters is motor power and that can be exactly the same. Also size but as far as I am aware there is little difference.

It's left me wondering if other than cost one type has other advantages over the other.

Anyone know ?

Normally I would avoid 2 pole motors like the plague if given a choice but maybe that is the wrong attitude to them.

John

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I'm pretty sure mine is powered by a 1400rpm cap start motor as I can hear the click. Low torque start so maybe no run capacitor.

It has proved to be an excellent purchase. Bought not long after they appeared from Grahame Engineering in West Brom.

Mods? I suppose I could investigate why it cuts a little out of square. Personally I feel a lot of mods for all sorts of things like this are done 'cause some one has nothing to do / that's the hobby. Bit like me playing around with old lathes now and again.

Mine has the simple lever switch cut out. I lift it up and the saw knocks it off when finished. It's one of the switches with an elongated tear drop shaped metal lever. Nice and simple. No NVR to go wrong.

Tried looking for Mike Cox web pages. Not sure if I found the right one - big wheels, quieter ? etc . Not sure if I trust Stubmandrel. I think he abuses small lathes and peers through telescopes.

One thing I should do to mine is paint over some of the rust.

John

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