Member postings for Ajohnw

Before getting excited they come with a health warning. Only really suitable for light work. A problem in that area is that they will take substantial cuts with a decent tool but the head may distort spoiling the initial accuracy which is surprisingly good. They claim that to be better than 0.0005in all round. It was on mine, easily. By that they mean taper and roundness of work. It also pays to watch out for swarf getting on the rack and keeping it clean while working. Also to have plenty of stub drills about above a certain size due to the limited centre distance. A stub drill be the way is one that has been reground so many times it's a lot shorter than it was.

Talking this area in general I advised a friend not to buy a baby lathe but to go for the mini. Completely ignored but several months after buying one he wished he had listened. The main reason he didn't buy the mini was weight. Odd really as they aren't very heavy at all. People get concerned about shed floors and all sorts of things. Might pay to bear in mind that a typical shed floor will stand some one weighing well over 100kgs standing on it. The thicker kitchen work surfaces ( about 30mm thick) make decent benches and with a bit of sensible support can even take a vice and have stuff hammered to death in it. My boxford mostly rests on a really old ply kitchen unit. Draws and doors still open perfectly and for it's size that is a very heavy lathe. My miller sits on top of some office type steel draws, the type that come in two forms shallow or deep draws. The miller weighs over 100kg. actually that is part supported by the kitchen unit as well. I packed up some 3/4 ply so that it rests on both the kitchen unit and the steel draws, had to as the draws are only about 300mm wide.

John

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Hollow ground screwdriver blades don't jump out of the slot. That's the whole idea of them. Instead of thickening from the tip they narrow slightly and actually dig in so little downward force is needed as well, just a sensible amount. They still need to be kept square. The pressures are so high that they will literally dig in hence the need for heat treatment to cutting tool levels.

Mine was stolen along with a number of tools from the boot of a car I was working on otherwise I would be able to be sure of a blade thickness. One thing I had noticed is that if the screw was of a suitable size for the width of the head or the screw head was larger it fitted well which suggests that there was some sort of convention in this area.

A method I used to remove a gearbox oil filler plug with a stupidly thin hex head that some one had rounded trying to get it out was to drill 2 holes across the diameter and tap in silver steel pins, carefully tightened an adjustable spanner of the King Dick type on them. Then found I needed 2ft of leverage to even loosen it. I suppose an alternative would be to make a spanner with pins on it instead but it that case I would most definitely taper and harden them. The trouble with the knocked in pins is that if the spanner isn't hard up against the surface being rotated they will probably just pop out and leave a bit of a mess behind them.

John

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Edited By John W1 on 10/07/2015 23:22:03

Can't agree Muzzer. Brian already makes longer one and has a die so the problem is holding an end that has been threaded while he does the other end on rather short ones..

If he taps a hole in something to take the threaded end he has done he can handle shorter lengths. It will probably make it easier to do longer ones as well. He may have to buy an NPT tap or may already have one. Personally to be sure of being able to easily remove the part I would drill right through what ever he chooses to tap and open out most of it to a size to suite some suitable screw and tap that section for this screw, the rest for the part. This way he can lightly screw the part he is making in it's end and then hold it firmly firmly in place with the screw - sort of lock screw arrangement using the same principle as lock nuts.

Michael touches on an interesting point. I sometimes use a drill chuck to hold things for hand work. He might find it will bruise the thread that he has done when it's tightened sufficiently to hold the part while the other end has the die run down it. A bit of suitable rubber tube or a couple of wraps with masking tape might help with that.

As to how THEY make them. A cnc machine could make them in one go. If they used capstan type techniques, one threaded end while on the tube, part of and place in a fixture and thread the other end. The fixture might be a collet or something along the lines of what I described above or earlier. If they make millions it can be very surprising how well parts can be orientated and placed in machines automatically. In that case one machine would thread one end and part it off, then on to another machine to thread the other end. All sorts of things are possible even automatic transfer of the part from one machining operation to another on the same or another machine. I get the impression that some brass fittings are initially cast so I'd guess the industry has this sort of thing well sorted out using special purpose machinery some of which might have more than one spindle.

John

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In return Michael might I mention that from the look of the plug the blade I described would fit it perfectly but each may do what ever they wish. Real coin slots are few and far between but if they are in this case the slot would need to be rather large to get a sensible sized coin in it. Some how I can't imagine a garage mechanic reaching into their pocket for one.

John

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Different make but looks the same style of motor to me due to the external capacitor.

He isn't far from me so I have visited him a couple of times but not for a long time. I sold my Peatol a couple of years ago but kept a few of the bits which will probably find there way onto my Pultra. I'm hoping to machine the 4 jaw I have to fit directly on the spindle nose to avoid overhang and get the 3 jaw and do the same but will need to do some size checks for that. The 3 jaw can be persuaded to grip as true as any collet if it's on a lathe that can turn very round and parallel. Just machine the faces while the chuck is closed on a washer pulled back into a small register at the back. Remove the washer and clean up the slight lip that's left. Grip - I've held sharp 3/8 end mills in it and cut straight through 3/8 mild steel. Also a 1/8 in woodruff cutter probably a bit over 1in dia to its' full depth. (Making a router fence.)

John

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Another option is to make a proper screw driver as they can't be bought as far as I am aware. We had some wooden furniture delivered that cam in 4 parts fixed together with a few brass slot screws. The people who did it had to get some one to make screw drivers for them. The key is hollow ground with a temper not far off one suitable for a cold chisel - dark straw at the most. A cold chisel can rough out mild steel pretty quickly.

All sorts of older things may be fixed with slotted screws even lathe chucks and the right sort of screw driver is likely to be needed to undo them. Chances are similar screw drivers would be used to fit these plugs and the people who did were probably rather strong - professional muscle usually is.

As it happens I made a fitters screw driver as part of training. Something like 3/8 square tool steel should make a decent one. Square so that a spanner can also be used. Get the end red hot and forge it to shape. Allow to cool slowly so that it can finally be shaped with a file. Blade width from memory 3/8 wide at the tip widening upwards and about 1/16 thick a the tip - best check some slots. Turn the other end round for an inch or so. Make a nice large mild steel handle of the right size to grip firmly slot the end to take the 3/8 square and drill and ream to take the round part, Knurl it leaving bare metal at each end. It can be hollow to get a balance to prevent it being handle heavy. Chamfer the end fairly heavily as sometimes they have to be placed in a slot and given a hefty whack with hammer. Grub screw in handle onto the round part of the blade to hold in place. The slot was finally filed to ensure a tight fit. Might be easier to roll pin or dowel it. Harden and temper the blade. As I have seen the square rounded over via use of spanners it might be worth hardening and tempering part or all of the shaft as well.

The blade end after filing should be dead square and dead parallel to close limits. The side of the blade is then placed on the edge of a grinding wheel at an angle to cause the tip to neck in by a few thou. This means that if a line from the tangent to the wheel is drawn to it's centre the tip will be some fraction of an inch above it - probably 1/4 in or so. Each side of the blade can be felt onto the wheel so that the blade remains parallel.

Silver steel could also be used for a blade but bang goes the spanner.

Well at least people now know why these sort of things may be extremely tight. It's no good trying to do the same thing with a modern screw driver. Might help but all are made of air hardening toffee these days.

John

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Edited By John W1 on 10/07/2015 15:24:12

If this crops up again. Peatol sell a nice compact GEC motor for their lathes. 1400rpm. They get a bit hot but this type of motor often does. The price was very reasonable and I'd guess it still is. 1/4hp £50 currently. Their lathe needs the power for it's nK top speed. There would be plenty available at normal speeds on other small lathes.

I had something similar to the flexispeed at one point, came fitted with 1/2 hp. Too much doesn't hurt really but as it was an old motor it was a bit big.

Whoops - I'm assuming the Peatol still uses the same motor or a very similar one as the motor board and belt would have to be changed if it was much bigger.

John

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Edited By John W1 on 10/07/2015 14:24:05

Some how I doubt if it's been mentioned and probably mostly of no interest at the smaller end but the 4 jaw independent will hold work far more securely than any of the self centring chucks.

This can be of interest where people have fitted a far more powerful motor so that they can drill larger holes in one go and in cases where there isn't much to hold on to. Might be of some interest in training establishments too because there isn't much chance of work being gripped unevenly. as it can be in a 3 jaw particularly short and or heavier pieces of material. Or any piece of material in some cases.

When the 4 jaw chuck is used like this there isn't any need to centre precisely. That only usually happens when work can not be done in one setting and the 3 jaw isn't accurate enough.

John

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You don't live in Treasure Island Britain so can probably get all sorts of things cheaper than us. An expression some of us use to explain the rather high prices we have to pay for some things.

On the other hand I linked to that site because I knew that they were bound to offer them. They are probably gas fitter quality and may be cheaper elsewhere.

John

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That is probably both safer and cheaper as it's then possible to see what rev ranges could be used from the treadmill speed working backwards. Many of the motors come with a fan built in.

They appear to use Chinese HP - what goes in rather than what power comes out of the spindle. I suspect they do that on some of the lathes.

If you fit a current monitor it would be best to use an analogue one as that will read average current - not far from the true rms value. Digital RMS meters generally have a very restrictive frequency range. As there are now cheap semiconductor current sensors about one may be built into the controller in the treadmill. They look like the ones shown in this link

**LINK**

I've wondered about them but say 1/2 speed is the slowest that they can be run. That means the speed range will be circa 2 to 4k rpm. On many machines that will mean a lot of speed reduction will be needed. Similar technology has been used on the cheaper mills and lathes for some time - probably why they use a noisy gear for low speed.

It also looks like some treadmills don't use permanent magnet motors. I've seen comments that they can be using series wound motors but as I have never looked at one pass. The series ones will run on AC also shunt wound if some use that. These could be controlled with a normal triac based speed controller or run on DC.

John

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As I mentioned earlier he probably wont be able to unscrew the item from a fixture if he just screws it into a tapped hole and the runs a die down the other end for finish it. I mentioned a simple solution.

Taper dies and taps are available but tend to be expensive. Also die head chasers from other sources.

**LINK**

John

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I have an interest in casting come up - parts for a telescope that I can't turn up on my lathe. It will save a lot of waste too as it will be mostly a hole. He's the best source of info I have come across and watching him work generally I get the impression he knows what he is doing all round.

He was also cutting thick steel with a circular hand saw commercially made for just doing that. Might be in the same video series. Not sure.

John

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Edited By John W1 on 09/07/2015 23:39:42

Easily found again

**LINK**

As usual though - no usability info.

To be honest having worked on electric vehicles that use this sort of DC voltage I am surprised they use DC at all. It's more dangerous than AC.

It's a little more complicated really but the torque characteristic comes from say 10 amps continuous at some flat out speed at 180v average. If the motor was run at 1/2 speed the average voltage would be dropped ot 90v by driving it with a 50% on 50% off waveform. The current limit flat out is due to resistive heating but as the motor is being driven with a 50/50 waveform the current peaks can be 20 amps for the same heating effects so power remains the same. There are complication though.

Actually I should know about permanent magnet motors and AC as I have a couple of 180v motors that came out of sheep shearers that I think are permanent magnet but having looked at the waveform maybe 20 years ago sorry I can't remember. Maybe some one else knows. A simple triac speed controller would do the job if they do.

John

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Edited By John W1 on 09/07/2015 16:48:56

All the 180v means is that the full 240v mains shouldn't be applied to them. ie ran at a bit lower speed via pulses so the mean value of the voltage is correct. As far as I'm aware they are brushed universal motors or brushed permanent magnet - probably some what over rated on the motor plate. If you search youtube you will find people running them on ac and dc. I'm not sure if perm magnet motors can be run on ac so there is probably 2 types about.

People have done this on lathes but I have no info on how well it has worked out. Brushes don't generally like being run in different directions but if the commutator is cleaned up with pcb eraser as washing machine people do and new brushes fitted it stands a better chance of being ok if the direction has to be reversed but the brushes themselves might be positioned to suit the direction the motor usually turns.

Buying treadmills with problems of one sort and another, breaking and selling the bits seems to be a bit of a popular occupation.

Actually I'm pretty sure I came across a web page where some one had used one on a drill. A search might bring the pages up.

John

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Edited By John W1 on 09/07/2015 15:46:45

You will need a tap as well but make with outer most thread done in the lathe and the o/d's turned. Part off to length. Screw into a fixture and run the die down the other end.

In this case I would be inclined to split the fixture and clamp it tight with hex screw otherwise you might have problems getting it out again. If you can't split things have a thread running right through the fixture and fit a screw pressed firmly against the part to keep it in place. It needn't be the same thread as the fitting.

These sort of fixtures could also be used if you are just hacksawing lengths of tube off.

I've also held threaded parts in a collet to do work on the other end. With brass though it might flatten the thread a little. These seem to be taper threads as well so collets wont be very good. You could make the fixture out of a blank ended one though.

John

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Sounds like a man from the yahoo boxford group that recently bought a Harrison. Curiously I have never used a Harrison. Many others but not that one. Maybe it's because I have only been around toolrooms.

Those video's mentioned are a good place to go to listen to what a slightly worn gearhead sounds like on the Monarch. Slight signs of stage 1 headstock bearing wear when he is testing it for rather deep cuts too. Recutting when it shouldn't but maybe the tool moved. It is often easy to see the early signs of bearing wear. Crops up when bright drawn is being lightly skimmed with a fine feed. Rings appear along the work due to variations in hardness from the drawing process. Heavier cuts or much coarser feeds overcome this but when the tool is run back down the work it will cut again and not just due to the bar bending as it's being cut.

Accurate work worn out? Depends what can be put up with. I had to use a Taig/Peatol to make a mandrel to fit the Thomas dividing head. Due to earlier abuse forming one side of a V pulley in one cut the head had bent so the mandrel had about 0.005in taper so I corrected that by playing with the cross slide as the tool was run along the work. Finished up parallel to better than 0.0002in, no joints to be seen and as the bearings in these lathes are very solid and it was virtually new a very high class finish. It can be done but I don't want this sort of bother. If the bearings had been loose bang goes the finish. Curiously the person who stuck a gear blank I also turned up on the end of the mandrel and cut it for me had a Harrison - he was very impressed with the finish - better than he could do.

It doesn't really matter what people buy there will be various shades of good and bad about.

Maybe the lack of noise from a gearhead machine is an indication of how hard it's been used and for how long.I heard one Colchester on ebay that personally I wouldn't touch with a barge pole but even that might do decent work if the right sort of cuts are put on at the right time. Sometimes very heavy chucks can help a bit. A new class machine will just make a subdued humming noise. In fact the motor is likely to be noisier under very heavy loads.

I saw mention of 38mm bore and 3hp earlier. Some of that relates to how long it's going to take to reduce the size of parts and how many drills will be needed to drill large holes in stages . It also relates to the material being cut. Some tool steels for instance do need power unless rather light slow cuts are taken. This may be why tool room lathes are often worn also the amount of work some do. Going on elderly machines I have used bearings get to be a problem before the gear head makes much noise.

If people add files and emery etc none of the above matters but jobs will take longer. My Boxford (ME10) is pretty good but I feel it would benefit from new bearings. Mostly because I suspect no one has bothered to adjust them when needed. It will still do accurate work though. Go to gear heads an it would be interesting if lathes co uk mentioned if they were adjustable. I know of one Colchester that definitely isn't. Chipmaster and the 3,000rpm isn't good for that spindle size bearing set up as good as it is.

John

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There is an interesting set of rolls shown in this video. He had the design published in Model Engineer around 20 years ago. The cranks at each end are phased at 90 degrees.

**LINK**

Odd thing. I have seen tin smiths rolling with a similar design but with gears. It isn't just thin tin plate that they were rolling either. Gears rather than cranks but the same simple arrangement. I would make the handle longer as it can be hard work.

Pinch rolls as per G Thomas gain a little if the material is reversed but having seen this design I just have wonder if it's worth the effort. Or the other type as well.

John

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It appears to use the idea that a slightly smaller drill than the required hole size will give fairly precise hole of the correct size so for running fit on 3/16 he would choose a number drill around 0,001" smaller. i have a feeling I would buy reamers to make some of them.

Going on the above the port in the valve is intended to come out 3/16 long. I know zilch about steam engines but wonder if the stroke ( twice the throw as used here) should be somewhat longer ? Some one on here that is into steam engines should be able to clear that up. Also maybe how much top clearance to leave in the steam chest at the top of the valves stroke.

John

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I didn't know that the internals on these varied. I am wondering if anyone has the words to go with the numbered parts of the top headstock arrangement show in this. The manuals I have seen only show the lower one that uses a thrust race rather than the sleeve round the spindle.

I have a photocopy of this page and it refers to the top one as the plain headstock and the lower one as the lever headstock. While I can manage it would be nice to have the words that should be in the manual referring to all of those numbers. The manuals I have seen do refer to all of the numbers on the lever headstock and include dismantling and setting instructions. One thing I find odd about the sleeved one is that the sleeve which forms the thrust bearing doesn't want to move which would make removal of the spindle rather difficult. Some trick may be needed to free it.

Ebay Pultra watchers may have noticed one complete with dividing head and the milling / grinding attachment. I'll be curious to see what that one goes for.

John

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You can hand chase male threads. Gets a bit tricky on small female threads - and larger ones too.

It's not as hard to do as some may think. The speed of the lathe needs to be fast enough to suit the pitch being cut. Too slow and it can be rather hard to get an even feed but as the chaser gets deeper it tends to mostly look after itself.

John

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