hi I'm Drew Klaber from Mitutoyo America corporation I'm here with Jeremy
banks and on today's tool tip we're gonna be discussing the difference
between skidded and skidless surface finish measurements so drew me my
customers have questions on when to use skidded versus skidless surface finish
right so do you think you could take a couple minutes and explain with the
difference between the equipment or maybe some different uses that you would
have with these devices absolutely and to start out before we really get into
the difference between skidded and skidless let's take a look at what actual
the components that make up a surface finish gauge so drew what do what
equipment do we have here right now so I have two units I have a skidded and a
skidless system okay these are both made by met tutorial but these could be
and in fact any brand of surface finished measuring system all systems
are made up of the same components you have a stylus and the stylus is the
piece that contacts the surface to do the measurements the stylus feeds into a
detector the detector takes the movement translates it into a signal that can be
measured and then we have the drive unit which pulls that the stylus and detector
assembly back and forth for the measurements that will plug into an
amplifier which is where you get your readings from now this is a skidless
system as I mentioned this gated system is very similar except you'll notice
that the stylus and the detector are all one piece here so I still have the
stylus that's protruding out from the detector but around it is a housing and
that housing is what we refer to as the skid right here so what's the purpose in
the skid the skid is going to act as a mechanical datum for your surface that
you're measuring on this skidless system that datum was actually inside
the drive unit so you're going to find that most entry level systems are going
to be the skidded unit with the housing around the stylus so drew now that I
understand the physical differences between the devices what are some
differences in application great question so let's take this pin for
example that nettabi pin it could be any customer application but it's a piece
that somebody needs to measure surface finish on is I'm looking to spend
there's really multiple areas that can be measured we can measure the top face
we can measure a long access of the pin we can measure over
the radius and that's really going to make a difference which unit we use base
off what needs to be measured on here okay let's just say one of the measure
along the axis okay so if you're measuring along the axis skidded unit
would be great because what's important with the skided unit is that after it
makes contact with the part that the skid is always in complete contact with
the surface that's being measured so if you look at the skid here there's no
gaps between the skid and the part anywhere it's not sitting in a kind of a
weird angle to where the beginning or the end of the skid is off it's nice
even contact to where if I were to move the stylus or the skid back and forth
it's always in contact with the part and that's important because the skid is the
datum if the datum isn't making good contact with the part you didn't
accurate measurements that is correct so if you were to measure along the axis
this part you'd be fine if you wanted to measure the top face of this part you'd
be fine as well I want to find one of the measure radially that would be an
issue with the skidded system so let's flip the part up here now if I were to
present the stylus to the area as I move the stylus back and forth across the
part you notice depending on where I am these are the beginning or the end of
the skid are going to be off of the surface it's being measured right I'm
either going to have a gap at the beginning or gap at the end of the
measurement right and this would be bad because that's the datum and it's not
making consistent contact with the part that's correct now if I were to take a
measurement with this I could probably spend some time with this set up and
actually get a number that's going to show up on my amplifier but that doesn't
mean that the number is a good measurement that I can trust okay so in
an application like this a skidless system would be better that's correct
so you'll notice as I bring a skidless system in for measuring that by not
having a skid I can actually bring in a stylus in contact with a surface I'm
going to get a very good measurement here you're gonna be able to trust these
numbers and you're getting from this unit so as long as I stay within the
stroke of the detector that's correct that's correct depending on the unit you
have that will vary how much actual stylus travel you have so as long as I
stay within my stylus travel I could measure radially across the part that's
correct that would be no issue to actually have a stylist trigger
from side-to-side obviously I'm moving the whole drag unit here but an actual
measurement process it would just be the detective news that sure that makes
sense measuring round parsed versus straight parts are there any other
features that would lend themselves to a skinless device versus a skidded
absolutely so let's switch parts for a second and now we're going to take a
look at a piston notice the piston has a small groove here yeah on the outside
diameter if we wanted to measure this groove it might be a little difficult to
do with a skidded system because as I start to move my stylus in you notice
the skid is larger than the groove that I need to measure so I could not
actually measure the bottom surface of the screw with a skid in units however
if I bring my skidless system in now you'll notice I can easily not only
reach the groove that needs to be measured but I could have still have
room to measure from side to side along that groove so let's say that I have a
part with a groove that's a little deeper or maybe it's a little more
narrow is there some flexibility and the type of styli that I could use
absolutely both the skidded and the skidless systems there are different style
line that can be used with that system so if you need to reach deeper within a
part or down within a groove maybe add a little bit of an angle for a gear tooth
we can accommodate for that there are more styli options available for
skidless systems and there are for skidded systems typically though okay so
other than the physical limitations of the workpiece is there is there any
other reason that you would use a skidded versus a skidless device it's
going to come down to what parameters you're measuring and when I say
parameter most folks are familiar with terms like AR AQ, RZ those are the
parameters that you're actually measuring with the surface finish gage
because it searches the AR it's a roughness parameter any gauge whether
it's skidded skid list can measure the roughness parameters if your parameter
starts with a W it's a waviness parameter we can't actually measure
waviness parameters with a skidded units because the skid itself will
mechanically filter out the waveform so if we're going to look at waviness WA WT
or common parameters we have to start with a skidless system for those
measurements okay great so Drew I gotta ask if the skidless
system seems a little more versatile why would someone purchase a skidded
system typically your skidded systems are gonna be your entry level systems
okay they're going to have a lower price point on the initial system itself once
you get into the skidless system though you'll find it the replacement styli
are going to be less money than a skidded system because on a skid less
the styli is or the stylus is a standalone and skidded the stylus
and the detector are both one one body one housing okay so fine a simple
measurement where I just want to measure a flat piece for an RA you know a
skidded where a skidless would work either way that's correct and if I want
to start measuring round parts where I want to measure grooves then I might
move into a skidless system exactly and when in doubt feel free to give us a
call look us up online we'd be more than happy to help determine which is the
best unit for not only your application but for your budget as well
would you really appreciate the time today my pleasure I really helped me out
if I could have my customers out as well very good thank you guys for watching
today's tool tip if you have any questions or comments please leave them
in the fields below if you have any suggestions for future tool tips please
let us know that as well also if someone ha some suggestions or some
questions about how they're measuring their parts absolutely leave them in the
comments below as always if you have any questions please feel free to give us a
call at 888 MITUTOYO or look us up online at www.mitutoyo.com