hello welcome to Enots engineering i'm Alan today i'm looking at the speeds of the lathe
ever since i've had my Boxford which is over 50 years ago it's always been hesitant to run
at the fastest speed especially in cold weather you need to warm it up get the motor working get
the bearings warm before it would even get anywhere near top speed
so today i'm looking at the speed of the chuck and the pulleys
and to do that what i've done is bought this hall sensor and the digital readout
i'll be wiring these up setting you up on the lathe temporary to see what speeds i'm actually
getting and whether there's a problem with the motor or whether it's something else in the system
let's go to the workshop see how we do it well today i will check the speed of the lathe
and to do that i've bought a digital rev counter here i have a battery pack with some batteries in
to give me power some connection blocks to connect the wires to a screwdriver
and this is the rev counter
this is a panel mounted ref counter so with this you get the digital display connecting plug
the proximity switch the magnet
what i want to do first is just see if the display works i've connected the battery
connected the proximity switch switched the power on and the display is reading zero
if i pass the magnet in front of the sensor you see on the back there the led lights and every
time that lights it takes a reading a pulse and you can see that the rev counter is indicating
the number of pulses and converting it to rpm
so that all works we'll now look at the wiring diagram
if you didn't get the diagram with the part you can get it on the internet
so the brown wire of the sensor goes into number one and a positive supply
a negative wire goes into number two from your power supply
on to number three is the blue wire from the sensor
and number four is blank nothing's not used number five is the black wire from the sensor
the voltage should be it says on here from 8 to 24 but i've been running this
on 6 volts and it still works now i need to go into the workshop
and set it up on the lathe then check the actual speed against the speed recorded on the data plate
on the lathe i've fitted the magnetic base to the top slide
holding that in the end is a washer and then the in the washer is a proximity switch
in the chuck i've fitted a metal bar and i've just clamped a magnet in between the washer and the bar
here's a magnet at the bottom as i rotate the magnet you can see on the top here
the proximity switch led lights up as it passes just turn the light out
this magnet is a flat magnet and not the one supplied with the kit
so if i put the lathe on
you can see the switch pulsing
that pulses each time the magnet passes the switch
so that's a reading without it running so i switched the light on this is on the slowest speed
according to the plate this speed is 210.
you see that's giving me to a reading of 224
this is with the lathe cold so if i change the belt to the next speed
that's set to the speed of 340.
it's coming up to 364
65 365
so i'll change the belt again to the next speed up and this should give a reading of 540.
that's set to a speed of 850.
it's stabilized now at 8733 and it should be 850 according to the plate
so we'll change it now to the top speed
that's on the fastest speed 1400
now i've set it at the slowest speed which is 210
and engages the back gear so that should now give me a speed of 40.
i've changed the speed again it should give me now 66 still in back gear
the machine's a lot noisier in back gear because obviously it's engaged
an extra two gears in the head which gives a lot more noise
i'll just try it on the next speed up
just to get an idea of the difference so now this should be a speed of 105.
so that's running at a speed of 113 just over
i'm just trying to think where i can fit the hall sensor on the lathe that's the hall sensor
it needs to be somewhere where it's giving you a true reading of the headstock speed
so really the only place i can fit this hall sensor is somewhere on the main spindle
you could fit it somewhere in the cabinet beneath but the problem is you'll never get a true reading
of what speed the chuck's rotating at because all these belts
are giving different speeds so you've got the motor at the bottom
that drives that shaft across the middle
where you've got your five speeds on the end so anywhere if you put the sensor on that shaft
it would only be telling you what speed the motors going
second shaft under here but obviously the speed of this is not the same speed as the headstock
because this will vary depending on what pulley you're on here and also you have
another pulley that goes up to the headstock the only way you can get a true reading of
the spindle speed is to fit the sensor directly onto the spindle
on this end of the spindle there's nowhere you could put a sensor
you'd need a bracket to fit this on and the other thing is you need a magnet
if you've got a magnet on this side of the chuck you're bound to get
swarf collecting in on the magnet that's going to cause problems so
there's nowhere here you can put a sensor \ so the only other part is on the other side
of the headstock with the gearbox is on this end
we have the gearbox
there's no there's no point in fitting on any of these gears because it's not the correct speed
this is the only part you've got here where you can fit
so that's what we need to do is fitness here
and to do that we need to make a bracket and fit a magnet somewhere there
and that way every time the spindle moves you'll get the true reading of the speed of the spindle
i've just fitted this piece of steel in and that will touch on the saddle
so i have a reference point
when i'm unscrewing the not the other end this will stop the spindle turning
next job is to move the gears out the way
remove this part
there's a cap head underneath here
that piece holds it in underneath now you should be able to move this out
the next job is to unscrew this what i've done is because the chuck's held
with the bar in it so it won't it won't turn or i can locate it back into the same position
i've removed two grub screws from this ring they have a brass washer on the bottom
that grips on the thread to stop it moving and now i'll put the spanner on to remove this
ring which puts load on the bearings
it's a spanner it's just a large socket with four holes around the outside and you put pegs in
around the outside i only need two now because it's not that tight
take this off
watch you don't lose the two brass
inserts are in the grub screw holes
so what i'm thinking of doing is drilling a hole in here and putting the magnets
in making the bracket come off here to hold the sensor
and what i did before i removed it i scribed a line across the edge
that lines up with a red mark on there so when i put this back i can put the
tension on the bearings or the load on the bearings back to where it was before
first thing i want to do is get the center of the part
so i can then spot drill and put a 10mm hole in I've put my centre finder in
zero my axis
8.735 if i move it back then to zero
that should be the centre i fitted the spot drill
in then i just want to drill down 4.5mm
now change to a 10mm end mill to give me a flat bottom to the hole
the next thing i want to do is drill small five 5mm hole straight through so that when i put the
magnet in i can push a small rod through from behind to get the magnet out again
now on the magnet i've put a red mark on the one side because the the sensor only works
with the magnetic facing a certain way so i've marked the way that it works so when
i fit this into the hole it will face out this is the finished ring
that's the hole i've made for the magnet \oh well that's it for today we'll finish
this in part two we'll see you next time on enots engineering