hello welcome to enots engineering i'm Alan in today's video we're looking at the centring
indicator that's the centring indicator it's dial indicator with the probe at the bottom
that centres the bore in the milling machine so let's go into the workshop and see how we do it
today i have this box from banggood it's a centering indicator
and it's used on a milling machine to center a hole
in line to the spindle
there are two styli that have a bent end
two straight small and a longer one
and another small styli with a bent end
so in this packet there are two small spanners
and in this packet we have a spring-loaded device to find the center of a center punch mark
and this is the main body of the centering indicator
and the last thing we have is this rod which fits in the side of the indicator and stops it
turning when the machine's running the first thing i want to do is just check
what error is in the dial indicator and if you turn
you turn the indicator without anything touching it that is the error that's already there
so this end goes into your milling machine spindle and to fit that i'm using a 10 millimeter collet
there's a flat on the stylus on all of the style i
it's a flat and that goes in line with the bolt that's going through the side
you tighten it up with the small spanners that they give you
but these spanners are only pressed steel so eventually they they wear out
so it's best to use a small spanner
and this is how it arrived and i couldn't figure out how this works
looking at this the stylus has to be at that angle before it works a dial indicator
let me get you closer
so that doesn't work the dial indicator till the stylus is there
and i could not figure out how this worked
i got in touch with banggood and they contacted the supplier
and they said that this nut here has to be tight
so if you've got one that's like this you need to tighten this up tight
it's a nut on the back one on the front
so now when this moves
the dial indicator moves
that took me some time to figure that out with the help of the supplier because there's nothing in
the instructions or i haven't seen anything where it says this must be tight i assume that this
lever here moved over contacted that and worked the indicator and it took me a while to figure out
that that's not a pivot point it has to be rigid so you can adjust it
so i'm trying to get that roughly straight doesn't matter if it's a little bit off
because it will still work the dial indicator
now the other thing you need to do before we work the part is at the top here on this there's a band
you have to take this
off
this is just stop it getting damaged in transit
now you can see as the lever goes in
the indicator moves up and down and gives you a reading on the dial
now there's a hole each side of this base
for this rod to go in this is the handle so you can hold the
indicator so it doesn't spin around with the spindle
now it recommends on the instructions this should be run
at less than 100 rpm and the slowest speed i have on my machine is 75
so to set it to 75 i need L
1 so L is here and 1
is there
what you can do is just put a magnetic base on the table just to stop the spindle spinning
lower it down
center the spindle by eye that's about right lower it down into the board
you can see there it's running out and if i turn the handle on the table
wrong way you see the whole body's moving up and down
and you can look this gap here
as you turn the table
trying to get it right worse there
pick the lowest point right there and move on to the other axis
that looks like the best i can get that
stop it lifting out the bore
now that's centred the bore up to the spindle
it's just a bit of practice to get the dial indicator needle moving the least amount
you can see that's there set up on the center
i've changed the bore for another component with the hole in and roughly lined it up by eye
so now i'll lower it into the bore just push the lever across to get it into the bore
make sure you're touching on the ball part of the probe we'll switch it on
using the x and y axis i'll try and bring that down to a zero movement
oh that was lucky
so
now one thing to i should point out is that the reading you're getting on here
is not a true reading you're only using the indicator as an indicator
in other words you can't say it's running out two or three thou or 0.1 of a millimetre
because you've altered the reading on the dial indicator by extending and using the probes
so i think it's best if i explain how this works this dial indicator is upside down what i mean is
it's working this way with the probe the ball part of the indicator probing part on the top
now inside here we have a disc that goes around touches the dial indicator that
disc is fitted to a spindle which comes down here and then the movement you get
is worked out on a lever here so if you move a millimeter on this lever
it might well it won't be a millimeter on the dial indicator
now we'll have a look at the center punch alignment
to change the probe under this bolt here the probe should drop out
and that's the center punch alignment probe
there's a flat on the edge of the probe
lower it down so there's a bit of tension on the end
stop that that's the nearest i can get the run out or the lowest run out i can get
so we'll lift this up replace that for a center drill and see if that's on the mark
you can see the center punch mark just lower it down
and it is in line with the mark i've put the pro back in and held it vertical and i'm just
interested to see how much error is on the dial indicator compared to actual movement so what
i'll do is move this block into position on to touch the dial indicator and we'll set it at zero
now i'll set my digital readout to zero
now move each division is supposed to be 0.01
so i'll move that in 0.01 on the digital readout
which is there
let's maybe the point
the digital readout says 0.055 so if i move it to off the mill
which is there the readout is saying 0.265
so you can see the error in the dial indicator
it's not giving a true reading now it should give a true reading if i come inwards onto it
and this is with the probe vertical so now i'll move my z-axis
down 0.5
that's 0.5
and even on that reading you can see
it's nowhere near it so you can't rely on the dial indicator as a dial indicator
you can only use it as an indicator a reference have run out
not a direct reading
oh well that's it for today hope that was interesting hope it was useful
and we'll see you next time on enots engineering