eBay Find: A Cartridge Style Electronic Gage Head

this is a cartridge style gauge head for a federal gauge amplifier if you were looking for one of these on eBay I'm sorry [Applause] welcome back to Cloud 42 I'm James you may have seen my previous video about bringing up a vintage Federal gauge amplifier that amplifier came with the classic lever style gauge head but I've been looking for a cartridge style head for it my friend Andre once again came through and tipped me off to a listing on eBay and I was able to snag one for cheap of course now that I'm making this video prices are likely to rise because the Tom Lipton effect is real I bought this gauge on eBay and this is what arrived in the Box this was advertised as New Old Stock military surplus and it does look pretty clean there's a little bit of debris there on the boot but I don't really see any signs of use it looks like I said really clean if you look at the connector here there's the part number ehe1101 and if you look at the connector I don't really see scratches in the terminals I I think this is New Old Stock this is the lever style gauge head that came with the gauge amp and it's actuated just by pressing on the lever as opposed to this which is a cartridge style that's actuated by pressing in on the plunger now aside from the obvious differences in the physical structure and how these have to be set up one of the major differences is that the lever style gauge is almost always in every realistic setup going to have some cosine error so that when you're actuating it at an angle onto a work piece it's not going to read directly you'll have to do some calculations to compensate whereas the cartridge style gauge will usually be set up perpendicular very much the same way as you would with a dial indicator in fact you can swap these in directly any place where you have a setup that uses a normal plunger style dial indicator like this Mar millimus you can just swap in one of these cartridge style gauge heads of course this one's a bad example because this indicator has an eight millimeter stem and this cartridge style gauge is a 3 8 inch incidentally it's the same as the mount on the lever style gauge though you would use them in different kinds of fixtures the connectors on these look pretty much identical my understanding is that any of the federal gauge heads that use this style of connector are interchangeable and these do look to be completely identical except that the connector is larger on the cartridge style gauge head and I believe that's because there are some electronic components in there but we can look at the schematic in a little bit and find out looking at this under the microscope though there is some trouble afoot it looks like this little rubber boot is held on with a couple of O-rings and one of them is completely split we're gonna have to replace that and the other one is not looking too good I don't know if this is just age it's probably just age if these really are military surplus New Old Stock and they've been sitting around you can imagine these O-rings are under pressure and they would deteriorate and crack eventually and that appears to be what has happened I have an assortment of SAE and Metric O-rings and this one looks like it's about the best match it's a little small but the next size up is definitely too big so I expect that the one that was on here is just stretched out a little bit and this is the correct one this is an a006 now getting this on is exactly as hard as it looks I am working under a microscope here with my giant meat fingers and a very sharp pair of tweezers the goal here is to get it on without damaging it and without poking a hole in the boot and the one on the end there went on okay I was afraid the boot was gonna kind of scrunch back when I tried to slide it on but it really didn't for the larger o-ring it looks like this is about the right size this is an a009 and the trick with this one is going to be to get it over the boot without damaging anything especially with these really sharp tweezers the O-ring is stretched quite a bit to get over this and it's pretty stiff so it is trying very hard to snap back and if I let go of it even for an instant it just rolls back up so I think the technique here is just going to be to try to work it over bit by bit hold it down and just keep working my way around I honestly wasn't sure if I was going to be able to do this the boot is just so soft and it just kind of squishes out of the way I was pretty sure that I was unrolling it as fast as I was rolling it in and came very close to jamming the tweezers through the boot there but I think I got it without doing any damage there are some marks in the boot there is a small hole in it but I don't think I did that I think that was there there's a little crack right here I think that was there before I mean if I damaged it I damaged it I don't think these boots are repairable if you know where you could get a replacement boot like this let me know but I think I'm stuck with the one I've got if we look at the manual for the gauge amplifier there's a section at the beginning talking about the gauge heads and first up are the lever type gauge heads the one here on the left is most similar to the one that I have we scroll down here's a section talking about cosine error and how to calculate the compensation and then there's a section on read spring type gauge heads never actually seen one of those and here's what we're looking for cartridge type gauge heads the one I have isn't listed I think it's most similar to the one on the left here but again I think these parts are from many different sort of vintages so it talks about how to use it usually used in a horizontal or downward gauging position it says to clamp it as near the forward end of the body as possible and use light clamping pressure so no set screws and it said the clamp should be of a non-ferrous material like brass or aluminum I don't have a brass or aluminum clamp for this thing so we're going to need to make something should be easy I do have brass there's a section on the theory which is kind of interesting there are three coils in this thing and the center coil is energized with a five kilohertz signal and as the slug moves back and forth it controls how much of that signal is induced into the two coils on the ends and the difference between those signals is what the amplifier amplifies there's a whole section here in the theory you can freeze frame and read it if you want let's go make something I just opened up Fusion 360 and Drew up a quick gauge head clamp to hold this thing we'll make this out of brass I've got some three-quarter inch round brass in my scrap bin that we can use and we'll just Mill this down to an eight millimeter square shank that'll fit into my height gauge and the other end will have a split clamp this will be a reamed 3 8 inch hole that'll fit as closely as possible to the gauge head cut a slit in it thread one side put a clearance hole in the other side and make a knob to clamp this together I'll just turn the knob also out of brass and we'll reduce behind the knob to make a little register to reduce the friction thread this for M5 and we should be in business now I assume that the objective here is to not have any ferromagnetic materials right next to the electromagnetic coils that are used for sensing but I'm not really sure if that's the only reason they're recommending aluminum or brass through this all into a drawing and those of you who've been commenting for years that I should switch to metric note that this is all metric I mean I'll accept the 19 millimeter stock which is really three quarters of an inch and the reamed hole which is 3 8 of an inch but the rest of it is metric I hear it's better got a piece of one inch brass round here and I know I know I I designed for three quarters of an inch but it turns out I have a lathe and of course that lathe has a one inch through hole in the spindle which this just barely fits into we'll just start by facing off the end and then turning a section here on the end down to three quarters of an inch which is the material that I thought I had when I designed this thing [Music] and then we've got that down to three quarters of an inch we're going to put a knurl on it now only the little knob section needs to be knurled but I'm going to knurl the whole thing because that'll give me a chance to get the tool adjusted before I actually end up in the part of the cut that I'm going to need this is the Hemingway sensitive knurler that I made in a previous video and the key with this thing is to get it about half on the end of the work piece and very gently engage it to allow the neurals to engage and align themselves so they don't drop a double double double double track and then apply plenty of oil start it slow and just feed across I am kind of paying attention to the depth making sure I get a full depth of cut get all the way across reverse it feedback out to the end release it and we're done that looks pretty good now of course we only need a small section of this so we'll turn the rest of this down to make the screw threads our first Target is the diameter of the little register that's going to actually Bear against the clamp when we get there we'll back the tool out and clean up the edge then we'll turn down to about 4.95 millimeters to thread this for M5 put a little chamfer on the end and then we're going to thread this with a die it's just the easiest way to do it in this size of a work piece get that in my tail stock die holder and just spin it on by hand the brass just cuts beautifully and the die makes really beautiful threads then we'll just part it off behind the knob I will leave the knob just slightly long then we'll flip the part around hold it in a collet so that we don't damage those threads and face off the end now I would like a little depression in here so I grabbed a boring bar and I'll just cut a little depression there's no dimensions on that it's just by eye put a chamfer on this side to match the one that I put on the other side and that is the knob complete but since I'm starting with round stock the first task here is to put some flat sides on it now I've just got this clamped up in the Vise and I'm going to bring it down I'm going to take away about half of the material I need to bring this to a total thickness of 12 millimeters they'll just rotate it put the machined flat side against the fixed jaw of the vise flatten another side and I'm just going to take the bare minimum that I need to clean up a 12 millimeter width then continue rotating it put the large flat side down bring it to 12 millimeters thick and then rotate it one more time and clean up the other side I'll just side Mill off the end and we have a blank that is 12 millimeters thick and it's the maximal width that would fit in that one inch stock I'll just locate the two sides in the end and come back and put in our 3 8 inch hole I'll start with a spot drill and then come back with a drill that is a 64 of an inch smaller than the 3 8 inch reamer that I plan to use now we'll just push this through unfortunately right before the drill broke through it grabbed and lifted the stock now because I'm still Drilling undersize and because I'm going to come back and ream it and it didn't move very much I think I got away with this I'll go back through with the drill just to make sure it's cleaned up and then we'll come back with the reamer to actually cut it to size and we should end up with a cylindrical hole that's perpendicular I couldn't see any problem with this after it was reamed so I think I got away with it now that could just as easily have yanked that up broken the drill and caused all kinds of problems but it didn't the gauge head's a good fit in the hole so I'm going to call that a win and we will continue just flip this over on the side and put in the Cross Hole for clamping again I'll start with 120 degree spotting drill and then come back with the clearance drill size and I'm going to run this halfway through I'm controlling the depth by raising the table with the knee crank because I want this to be as rigid as possible and I don't want to overshoot and then we'll come back with the tap drill size for M5 and being super Ginger pushing this through because I do not want it to grab I haven't brassed off these bits and I don't want to have a problem unfortunately it's a small enough drill and the Vise had a good enough grip that it didn't have a problem then we'll just come back and power tap this for M5 you can hear the characteristic squeak of the brass feel underneath just to make sure I've been all the way through and then we'll just back that out and that should be that the threads fit nicely that'll work okay now we just need to Slit it and I'm using a piece of paper here to touch off on the top wait for it to be grabbed out of my hand and then do the same thing on the bottom and unfortunately this is Post-it note paper and I put it in there with the glue side up so it stuck to the work piece and it didn't grab it out of my hand and now I've got hot melted glue under there so I'm just sort of feeling with the paper and I'll use that to establish my Center we'll split the difference between those two positions and then just go ahead and run the slitting saw through this is a forty thou slitting saw and so it's about one millimeter and it just cuts beautifully through the brass not bothering with any lubrication and the chips seem to be clearing out of the gullets of the teeth really well that was totally uneventful no dramas at all now we just need to Mill this down for the shank and you can see I'm using a parallel to space off of the end stop and that's because I need to Mill off of that end of the part but I need to keep the other end of the part out of the Vise Jaws because it's going to be thicker when I flip it over so that's just a compromise so that I can meal off of this end of the part and we'll just bring this down it's 12 inches thick I'm heading for eight so we'll take two off of that side flip it over take two off of the other side now you may have noticed I'm deviating from my drawing and that's because I wanted to have the clamping region as long as possible figure there's no reason to bring that down to 12 by 12 and then I'm going to offset the shank to one side to give myself as much reach down from the position where this clamps into the height gauge as possible you'll see when it goes on the high gauge why I did that now we just need to do some deburring and this part should be ready to use I've got my 12 inch height gauge here on the surface plate and that's what we'll be testing with today this is not the Ideal tool for this it's not as rigid as I would like but I am planning on making a proper comparator stand at some point but this just goes right in in place of the stylus and we can mount the gauge head now this is the acid test just a little bit of finger pressure and that is nice and solid quarter turn it releases maybe an eighth of a turn is all it takes and that thing just locks up nice and tight you can see the reason I have this offset is so that it can reach all the way down to the table this is the way the stylus is designed on this and pretty much every other dial height gauge and this offset allows me to clamp near the end and still reach the actual gauging surface on the granite now the one thing I did screw up here is I got the knob on the wrong side I wanted it on the front but it's on the back because I put the part in upside down when I milled down the eight millimeter Shank I'm not going to remake it but it's always going to be there waiting we got the gauge amp here it's still got the alkaline battery pack in it that I put in it last time flip this over so you can see and plug in the gauge head connector fits so it should work I'll flip this on to the first position and this is for setting the gain and you can see the gain supposed to be up here and it's not even close so we need to adjust that and this requires a long screwdriver I actually had to go buy one bought this little wiihoth that is long enough and small enough because the set screw is way back in there for the adjustment and unfortunately this is all the adjustment range I've got I can't get it anywhere near the okay position if we go ahead and set it to the measurement mode just see what happens very little happens in fact when I press it in it goes down a division something is definitely wrong here I think all these gauge heads that have the same plug are supposed to be compatible Let's test with the lever gauge and just make sure that everything's still okay and if we put this in gain set mode it's off the chart okay that makes sense because I was messing around with the adjustment let's turn that back down pot seems a little bit scratchy but it seems pretty easy to get it into the right range okay put it in measurement mode and we get full needle deflection this is behaving normally so there's nothing wrong with this gauge head there's nothing wrong with the amp this looks just fine it just has something to do with the cartridge gauge head I think all these that have the same connector are supposed to be compatible now I don't know what's going on here but the problem is staring me right in the face I just haven't realized it yet it's late I'll get some sleep and I'll pick it up again tomorrow well it's a new day I slept on it and I woke up this morning I knew exactly what's wrong let's take a look at the schematic for the gauge amplifier over here on the left is the oscillator this is generating the five kilohertz signal that's being fed up to the coils in the gauge head and then the signals that come back are being Amplified through a chain of transistors ultimately to drive the needle if we look at the circuit for the lever gauge head you can see we've got our three coils in here and we've got I think four passive components and those are wired down to the connector if you look at the cartridge type gauge head there are quite a few more components in it but the interesting thing here is if we look at the connector on the lever type gauge head you can see that pins one three and it looks like eight aren't actually connected to anything because there's no connection in the gauge amplifier there's no reason to have those but in the cartridge gauge head there are connections to those pins now I don't think they're really using them for anything I think they're just using them as terminal strips to mount these extra components that are inside the connector but there are connections to those pins now if you remember my amplifier has these two extra wires hanging out the back of the connector so what are those for well somebody has taken the two wires from the meter and used a couple of these unused pins in the connector to Route those out for some kind of external connection maybe data acquisition maybe something else but what that means is that when you plug in the cartridge style gauge head you've got some of the internal circuitry in the connector actually cross wired directly to the meter and that short circuit is bound to cause some problems and I'll bet if we disconnect those extra wires as somebody added this thing will start working it's tear into the back of this thing again these three standoffs just come off and then the whole back cover lifts out that provides access to the battery you will be seeing this again enough of you have yelled at me in the comments about using alkalines that I am going to do something better about that then the inner panel comes off and we can see the wiring these are the wires in question this red and black wire that go right down to the meter and these go up and connect to what looks like pins one and three on the connector now I am going to write down exactly what is connected to what just in case something goes terribly wrong and I feel the need to put this back later I also don't really want to mess around with solder on this thing so I'm just going to cut these off flush with where they're soldered on you know I can always clean this up later but this is going to be fine and it'll allow us to do a simple test without risking damaging anything those disconnected from both ends and then I'm going to take a good hard look at this connector and make sure we don't have anything shorted or contaminated or anything that's loose that might cause problems later and that all looks good so let's button this thing back up inner panel goes back in bring back the battery for now but on the back panel put on the standoffs and let's give this thing a try plug in the cartridge gauge head flip it over and yes it's upside down don't worry about it and that looks a lot better that's close to being in the right range so let's get this set back up on the surface plate and test it got this setup back over on the surface plate let's power it up and see what we get as expected we're really close now this was zeroed on the other gauge head so there do appear to be some differences between the heads I don't know if it's between the styles of heads or it's just between two individual heads but we can adjust the game get it into the right range and we should be able to take some measurements and do some inspection I've got a one two three block here this is one without holes that I bought I think I bought this from Amazon I have no idea what the quality of this thing is like we're about to learn a little bit about it get the gauge head pre-loaded on there and get it zeroed now this has a a course and a fine adjustment on the same knobs which you're supposed to do is push the course adjustment Pass center and then bring it back with the fine adjustment that works pretty well get that zeroed and let's see how parallel the ends of this block are looks fairly repeatable and oh yeah that doesn't look great that's what four tenths over the course of less than two inches that's not a great block this isn't a good start yeah there may be some re-grinding of these in my future let's go ahead and dial this up to the Max and see what this thing looks like now this is one ten thousandth of an inch full deflection on the needle so plus or minus one tenth and yeah this doesn't look great though there's something a little bit weird going on here depending on which direction I push it I am getting some strange readings I wonder if there's an issue with slop in the plunger on this thing actually nope no it's just the base of my of my height gauge yeah if I just wiggle that a little bit or just bump it I'm getting a huge influence now keep in mind this is a tenth full scale I'm being ridiculous here but this height gauge is definitely not up to this challenge I'll I'll build a proper comparator stand here at some point now keep in mind if we dial this back down to where we've got two thou for full deflection we're only moving a couple of tenths which is just fine for a digital height gauge that only reads out to the nearest thousandth I think this style of gauge head is going to fit more easily into the kinds of measurement situations I usually encounter and it's also nice that I can just swap it in for a mar Mila mess or even just a standard dial indicator without needing a new setup the tip pressure is a little bit higher than with the lever but there's also no cosine error so I've got that going for me which is nice if you enjoyed this video or found it helpful give it a like subscribe and maybe think about supporting the channel over on patreon patrons get access to downloadable files for all of my projects and a little peek behind the scenes from time to time thank you for watching [Music] foreign

Channel: Clough42

Views: 36,721

Keywords: gage amplifier, federal gage amplifier, gage, mahr federal, mahr, electronic height gages, gauge, gages, surface measurement, test indicator, cartridge gage head, brass, lathe, metal lathe, mini lathe, lathe machine, lathe tools, lathe machine working, machining, vertical milling machine, working of milling machine, milling machine working, milling

Id: X4wjRwevNCs

Length: 26min 52sec (1612 seconds)

Published: Sat Jun 24 2023