Hi. In this video I'm gonna show you how to prepare some
under/over drawer slides for full extension drawers
to turn them into linear glides for use in homemade
woodworking machinery.
I use modified keyboard drawer slides for the slides in this
horizontal slot mortiser, for example.
So, the slides allow it to glide parallel and very precisely,
very easily, so I can just control it with one hand
from the lever off to the side.
Some people try to use these telescoping drawer slides
but those are actually not an ideal choice for a linear glide,
because these slides have to have a little bit of play to
accommodate for inaccuracy in the cabinet.
Let me show you. So if you look closely on here and now
wiggle that drawer back and forth,
you can see how much play that actually has in there.
That's by design because otherwise the drawer could get
tight if it was just a little bit off.
A better source of material is these older style over/under
drawer slides. This is an older style of full extension
drawer slides. And they accommodate a little bit of slack
because they can just twist this way to accommodate
width differences. So they don't need to have as much
play built into the mechanism.
Another slide that can be useful is this sort of keyboard
drawer slide. These can be hard to get, you have to order
them from a specialty place like Lee Valley or Rockler.
But a keyboard drawer slide you can get at Home Depot.
These ones also don't have to have a lot of play in the
because these brackets actually the thing can just
twist back and forth. So, to start with, I have to take this
thing apart and it won't actually slide all the way off
because there's a stop on the end.
So the first thing I'm gonna do is I'm gonna cut this off
with an angle grinder.
So, now we have these internal slides
and they're attached to this
S shaped piece and I have to get those apart.
So the thing to do is to get rid of these spot welds
which I'm gonna drill out.
To help my drill stay on center
when I drill these spot welds out,
and I'm gonna center punch each one of those.
Now with my drill set to the lowest speed,
and a drop of oil on each of my spot welds.
Now if my holes are big enough and exactly on the spot weld,
these should come apart.
I don't want to apply too much force because I might
bend it a little bit.
And that would be bad.
It's just the one spot weld left.
I guess I need to go like this.
Now I'm taking the longer of these two tracks
and I could just slip this one in here
and I'll call it done.
But I actually want a little bit more support.
So I want to put more ball cages in there.
There's also these two stops here,
which prevent the ball cage from getting out of the rail.
So, I'm gonna grind these flat so I can put the ball cage
from this one in here. So I have a much longer track of balls.
So now with the stops removed,
the ball cage can travel the whole distance.
Now I'm gonna put the second ball cage in there so I get
much less travel, but this is actually a pretty useful glide
already. Now one of the things about this glide though is
it's got a little bit of play towards this end.
You can hear it wiggle.
And I want to tighten that up a little bit.
So the first thing I need to do is get rid of that long
ball cage so I can work on that a little bit.
So, you'll probably end up doing this by accident,
always be careful to catch all the little balls.
So, let's clean everything because we probably
contaminate everything just with metal shavings.
So we'll just have to re-grease that afterwards.
It's also important to clean the balls.
So now I'm installing the short ball cage
and this is a really tricky bit. A procedure that works for me is
to put the balls in on the topside
and let gravity hold them
and then slide them in one at a time on the bottom side.
It's really fiddly work.
Now I'm not even gonna put all the balls in this one.
because I only want a short distance with balls in it.
And put this in here.
So now I can slide this along and figure out
where it's loose and where it's tight. So, for instance,
right here it's loose,
and here it's tight, tight, tight.
So, it seems to be loose primarily on this end
so I need to tighten up this end.
And now what I'm gonna do is
I'm gonna use my vise
to squeeze this side
so it becomes tight.
And this is where I have to be really, really careful.
So I can't just put it in the vise and squeeze it while
it's here because any amount of pressure
will actually cause this to flex enough to make it tight.
And then we're just gonna crush the inside.
So, we need to squeeze it past there and then
let it come back. And this is a matter of trial and error.
So I'm just gonna try turning it to here and back out
and it's still loose so I go a little bit further.
And still loose. Let's go a bit further.
And now it's gotten tight so...
we've gone just far enough.
And still a little bit loose in here so let's apply the same
procedure right here.
And that's tight now.
So now with just a few balls in it,
this glide is nice and tight along
it's whole range of motion.
And it will get even stiffer
once I put all the balls in it.
Now I don't want both full ball cages in there because
that cuts my range of motion too much.
So what I'm gonna do is, I'm gonna cut this off here
so that I have like 1 and 2 thirds of a ball cage
in here to get the right length.
So now I'm gonna mount these tracks.
Now the catch with a track like this is the screws have to
come in from the other side so when the track is put
together, you can't really put the screw into it,
so I've taken my tracks apart again and I've got
loading holes in them. So I've got this one screwed on
already and this one, I'm gonna set this one to be
exactly parallel by using these 2 spacers
to get the distances just right. Now the spacers hook up
on only the right edges and the reason I'm doing that is
when I then need to mount these sliders, which are
a different width, I can hook these in the same way.
And I will get exactly the same spacing because it's
always right edge to right edge.
So now I'm ready for a test fit.
I've tightened these down and made sure these are
exactly parallel.
And then the mating side,
I inserted the ball cages
and I loosened the screws on these so that
these will adapt to these ones exactly here.
And the other thing is these tracks have a stop for the
ball cage here, which prevents it from going out this side.
Both of these. And then on here I've got stops
this way so now I'm gonna insert this from this side
and I'm gonna push it as far as it will go
so that the ball cages are gonna be trapped between
those 2 things and forced to the same place.
So, let's give that a shot.
So now I've got 1 dimension of slider in place here.
For the slot mortising machine, I would put another set
of sliders to go in the opposite direction on top of that.
For the machine I'm building here, I don't need to do this.
It's only got 1 direction of motion.
If this were a final assembly, I would have
greased up the slides again because right now
they're put together without any grease.
And I would have put all the balls in it.
But right now I'm just putting this thing together to
see how it all goes together.
And once I've got the rest of the machine built,
I'll take it all apart, varnish it,
and then put it all together finally.