Hardened bushings

[Music] today I want to talk about heart turning and general machining hardened materials and the reason for that is because I have to make a bunch of parts that are hardened and relatively precise so I decided to to machine them in a soft state harden them and then machine them to final dimension in a hard state this piece here is sixty Rockwell hard so it's it's file destroying heart if you hit this with file it will score the file can show you on this part here that's that's really hard same for these smaller parts back here I turned them like this out of l2 drill rod which is 120 to 10 in the eyes of world held it here turned it and pre-drilled it five millimeters final diameter will be six millimeter ID I'm going to after hardening now I'm going to hold it here on this larger diameter finish turn the whole ID face it do this precision chamfer here there is a relatively precise dimension chamfer on here and turn the OD then I flip it around and just face off the access sixty Rockwell is of course not trivial to a machine normally but on the lathe with CBN tooling it suddenly gets really easy and I will show you show you how this works these here are finished on the OD and I D I just have to polish up the dod do the facing cut precision chamfer on one or two of the parts and run a laps through the center to clean up the bore I reamed them slightly undersized and I'm going to use a reamer and 1 micron Diamont lapping compound clean up the bore and make them a nice fit here is the lap shop mate brass lap Fortuna mid bore they're really simple we'll talk about that later no but Oh at the lay if I'm holding the part and a 5c collet and I have a CCM T turning tool here with a CBN insert the usually I buy boxes of CBN inserts that are used and then I do a a slight regrind or real app on the cutting edge and for my use then they are pretty good for for quite some time and it's very cheap to do it that way normally if you buy a single cbn insert with one cutting edge yeah that's about 25 to 30 euros for one insert gets very expensive if you by parting insert or threading inserts with cbn I try to do as much on my own with you cbn but don't don't let that stop you from using CBN tooling look on ebay talk to people who use cbn on the job and throw them out after when they show signs of wear many ways to get get going that way so doing some facing now I'm running at about 1200 rpm when you look hard turning videos on YouTube must be most industrial environments run CBN insert the crazy speeds and the chip flows off like lava networks the CBN can take that but I found that if you go a little bit slower it doesn't hurt the CBN cuts just as fine and you don't have to deal with nearly molten hot chips and you don't put as much heat into the work so working to precise dimensions gets easier it can take very very shallow passes with a CBN insert but also surprisingly heavy cuts not with this one because I reground only a few yeah maybe one and a half millimeters of the cutting edge let's go [Music] [Music] [Music] [Music] [Music] [Music] there we go now we can take a measurement of the diameter should be around thirteen point two eight millimeters yeah that's pretty close thirteen point two nine okay yeah we are a few microns oversize this is the this is the 4 millimeter CBN boring bar that I made it has a formula 1 car per chanc which is just a broken shank of an M mill and I have a small piece of CBN silver soldered to the end this year this tip here is what's doing the cutting action all the other here is just spare CBN and where do I get that CBN I'm glad you asked I got I got a whole box of these weird cbn inserts these go in a lower in a faced mill for heart facing I think this that's made by lucky amount that's German company they make CBN and Diamont tooling and it has a convenient large piece of CBN silver soldered or braised in there and if you heat this up with a small torch you can take this this piece of CBN and just pull it off of pair of tweezers and it has already silver solder on the backside because it was silver soldered in there and then you can take your car back blank you flux it up you put a little bit of silver solder on it and let it flow apply more flux drop on your piece off CBN hold it in place heat it up with torch let the solder flow and then you have a CBN boring board which normally would cost you an arm and a leg then I ground ground it to shape you can't grind cbn on normal diamonds will our resin bounce diamond takes relatively long to grind it compared to carbide the cutting edge needs preferably to be left Robin and said he talked about lapping CBN tooling Instagram quite a lot and that's definitely the right way to do it I usually use a d40 diamond wheel which is very fine to finish grime my CBN and it seems to work okay ish but I'm looking to get a diamond lap a ceramic lap with diamond on it you cannot you not really use a cast iron or aluminum or copper lab4 lapping tools like this because when you present it to the lapping disk which is relatively soft material if it's not ceramic the cutting edge will dig into the lapping disk and create havoc so that's the reason why ceramic lack left is a good idea CBN usually gets ground CBN in general is neutral and has a tiny tiny negative rake edge break I think it's called a kale and if you grind it positive or even neutral it usually doesn't stand very well though after that's the magic behind CBN you can see the reflection of this edge chamfer here and that's the the negative raked chamfer on the on the cutting edges that I talked about of course in frontier in cutting direction we have that too a little bit hard to show again here you can see the reflection of the negative rake I should have poured the bushing in a soft state little bit larger hard turning from five up to six millimeters a bit annoying because to get a borne bar in a five millimeter bore it has to be quite skinny this one doesn't even fit so I have to take a fairly beefy cut on the first pass to get to get the boring bar even in the hole and it's a fair bit over Center which is also not ideal so this is going to be a little bit squeaky oh by the way the chips created by Hart turning especially the very fine dust that we get now from the ID boring this is really deadly for your slide ways on a machine there is a good reason why this machine has all its ways covered okay took me a few passes to sneak up on the final dimension but I hit it pretty darn good a tiny tiny amount about about three to four microns oversized to six millimeters I don't have a 6mm the gauge pin here but I have a six millimeter carbide shank with which is 5.99 so 10 microns undersized that's a nice nice sliding fit so now we need to cut a relatively precise chamfer you now we have to cut the relatively precise and a half degrees point one five millimeters wide so I could grind a custom tool for this but if we CBN that's not really economical because even a you cbn insert costs quite a bit of money we're not going to do that I prepared this earlier I saw Robin red said he do this it just takes a regular CBN insert and he clamps it at an angle in a tool holder like this to do certain chamfers and I tried it and it it works it really works well this one here is set up to do the eight and a half degree chamfer and this one is set up to do an 18 degree chamfer and the way you set this angle is relatively simple you do your math and you calculate your your triangular relationships I did the math for two millimeters of travel in and diameter that results in a sea travel of 0.29 millimeters and to do this we get an indicator in here and we drop it here against the cutting edge move it to a convenient dimension like zero then we move our dro or our x-axis according to the Dro two millimeters in and we look at our dial test indicator and when you get our point to nine millimeters the angle of our cutting edge is correct and if not we loosen the screw very careful and we take a small copper drift and we move the insert around until we get the correct angle okay here's better view I'm running the tip of the indicator along the cutting edge of the of this insert and I moved exactly two millimeters and I got point two nine millimeters of travel here so that's correct okay how to figure the the angle dimension relationship out you need you need to know the angle you want to go in this case eight point five degree then you draw yourself the triangle this is just for helping this is this angle is eight point five degree then you take an arbitrary number like two millimeters that's the length you're going to sweep over the cutting edge of the insert and this down here is X this is how much the indicator has to read so if you look our trig functions up this is 10 tangent 10 tons of the angle 8.5 degree equals dimension x divided by 2 we pull over to by multiplying 10 8.5 decree multiplied by 2 equals x x is equals you hit this in your calculator of course 10 guns 8.5 x put two point two multiplied by two gives us zero point two nine eight zero point two nine eight so yeah that's that's the way to do the math on how to set your cutting tool at a and uh precising and why do you not just put the compound on and cut it with the compound because that's annoying if you do that you lose all your offsets of your two in the Dro and if you have to do multiple parts it's even worse because then you're just swinging around to the compound like crazy all the time so I prefer to to put the tools on an angle I plan to to design a lathe chamfering tool that can be set that has a small dial that can be set for angles very much like the adjustable angle chamfer Mills okay this is easy now we're just touching off on the corner I'm going to blew it up and then I'm feeding in point five million C direction okay art finished you saw me facing off the other side turning it to final dimension should be relatively close to sixteen point three and the ID gauge is very nicely with a carbide shank that's usually ten microns undersized when I when I push the the pin I use this like a gauge pin through there is a little bit of a resistance in one one spot it's not very bad but I might run the laps for it to to get it nice and straight let's see does a dollop in dollop in is usually a smidge oversize this one is yeah it's about five micron oversize so let's see if this goes in there should be yeah it goes in but on the weird spot that I felt with the other one doesn't go through yeah the bore is a little bit Bell mouthed on both ends as far as I can tell with the pins gauge pins or pins in general that you use it on a bore can tell you a lot gauge pins are usually one of the nicest way to check bores in my mind you get a feel for the diameter you get a feel for the shape of the bore you can check the ID the position and a lot more just with gauge pins or with known good other pins this is 0.5 point 9 9 this is 6:05 so I know the bell mouth in here is roughly 6.00 millimeters in diameter just with two very inexpensive pieces of of stuff to check it so next would we'll have to polish up the OD of these parts and face them to length not much work on these one gets chapter again I'm using a jeweler saw to slit this piece off six millimeter round brass to create an expanding lap to let the idea of those two bushings to final dimension next I will drill tap the end for a screw and when I jammed the end of the screw into the the lead out of the thread it will expand the lab okay half the the brass lap I drilled and tapped the end for an m4 set screw the set screw runs on the end of the thread and expands the Arbor just holding it a drill chuck running it at 500 rpm I have some 1 micron diamond compound here lapping compound and some wd-40 for lubrication so we apply a little bit of the diamond take our first bushing slip it over and add a little bit of lubrication we need a little bit more drag right away it was a little bit too much I'm adjusting the setscrew and I moved the part up and down to feel the drag of it and this seems good now so now it just let the machine run and do our lapping which ends in endless up-and-down [Applause] this Plex much you can see here this is the abraded tool steel I switched to 3.5 micron diamond paste because the 1 micron went about a slow-ass continental drift so applying a little bit more I'm almost there I clink the bushing with isopropyl alcohol blow it out to compress the air and rinsed it again with as propane alcohol I checked the the doll pen if it's straight otherwise you get very weird results I just spun it in a V block and put on the test indicator on top and when we check the bushing now that's exactly the threat I was after a very nice sliding fit honor on a 600 5 millimeter pin okay I'm trying to show you difference in finish here the left bushing is only hard board with the CBN tool this one and the right one is left with 3.5 micron diamonds as you can see the right one has really shiny finish and due to the macro lens it's real tough to get it in focus so you see that the tooling marks are pretty much gone and after shiny surface not a really gauge quality but for the purpose of this bushing weighing good enough and this one is just hard board so you see some some tooling marks in there and some dirt this angle you can see the tooling marks very much so that's the reason why I'm lapping these and also the bores have some shape to them okay i lapped all the IDS for these six millimeter parts and I got them to a very nice fit very nice sliding fit but doesn't fall out so we were very close to an interference fit which is perfect these parts in operation these parts need to be sliding because they will be spring loaded with some heavy Belleville washers and [Music] perform the metal forming this tool is going to do here's the lower body this is three part this is the lower body did it's this disc and there's this bushing it's all goes together and I left the bore in the body and in this disc so this is also a nice sliding fit because this this bushing will be spring-loaded from down here with bail with washers to next step will be to lap the two millimeter ID holds in these bushings so this two millimeter pin that I'm going to use as a guide fits through all the way these are reamed dreaming and then hardening usually leads to a smaller bore because most fuels grow a tiny amount when hardened and the lap for the two millimeter holes is just the same as the six millimeter one piece of brass I slid it with a tiny abrasive cut off will die grinder and there is no room for a central expander screw so I'm just using a small screwdriver in the slot and by twisting the screwdriver I flex and expand the Arbor I did a lap by bending it a little bit these are available commercially tom lip and show these once there are something called like your whole lap or needle hole lap or something like that and I cannot get them here I can get very high-end laps from a Swiss company for a small time in a boss but those are ridiculously expensive so I make these myself that's what we're going to use to clean out these bores in these these small bushings back at the milling machine and that's the small Arbor small lap I'm applying some 3.5 micron diamond paste this one does not have grooves for the put a diamond compound because I figured that the large expander slot that I put in is enough for this purpose so then we try to get this on here add a little bit of wd-40 and go for it thousand rpm [Music] and the 3.5 micron really cuts fast a few seconds and we have a very nice fit here there are grilled for clearance from the back about two-thirds up so it's easy to put them on the lap that way okay there we go second one nice sliding fit and you might have noticed that I didn't have to expand the lapis so far I expanded it once a little bit over two millimeters and this design allows for some spring back so if you push it over a bore it almost works like a flex hold that you use for engine reverb hydraulic reverb stuff like that this kind of follows the shape of the bore a little bit but when you have some when you pay attention on how the the part drags on the lab you can very precisely and very accurately control the shape of the bore this design also has two drawback that you can create a board that's not straight if you if you hold the part very much an angle it will fall create a rear shaped hole I I just love this it's a little bit tight on the end I I will do deal with that but it's really close I always keep in mind these are all hardened components you're working on okay this is good and those few seconds of lapping you just saw that changed the shape of the hole enough so this pin now goes in with a constant force over the whole length measured with my calibrated right in finger yeah very constant showing you how to remove the CBN from one of those inserts works the same for any other standard cbn insert with a carbide or steel body using oxy-fuel torch I think you can get it off with something like a map torque to do it the oxy with the oxygen added the flame is much more intense and you have a better chance of getting getting the the cbn off before you die of old age setting for a nice flame that's a nice flame I'm using a tungsten tungsten ticket roll dasa as a poker heating it up just this insert just sits in a the slot of this aluminium fixture and this little mini fixture obviously is way colder than the environment because I get a lot of condensation on it but that's not an issue there we go there is the CBN there is the steel body this goes in scrap and here is the piece of CBN it has already a ground cutting edge here and here the radius here on the back that's just a radius and now you can take this the back side already has silver silver solder or copper copper braze on it so I didn't show you hi did did the brazing or silver soldering on on a carbide boring board that I used or CBN boring bar but let's have some fun with this CBN that I just unsoldered from the milling insert let's make a DC empty cbn insert I took an old DC empty carbide insert and I ground a large step here just holding holding the insert with the vise grip up to a diamond will of deep it grinder and do the cbn the chunk of cbn that i have fits in here right right in place like it belongs there so let's do this and then we'll do a grind on it oh that's that's very elegant so flux it because somebody will ask this is font art gain F 308 ultra ante had a small dab of it we don't need a ton of it especially not where we do not once are now we're going to put some silver solder on there I have some Chet a 30% one millimeter silver solder here that I'm going to use and again my my small micro torch we're going to heat this and we add some silver solder okay there we go I would take our our CBN place it here and hopefully it doesn't fly off when we start to heat it let's try doing a little bit more of a gentle flame last flame a bit a little bit a corrosive there we go this won't win a prize but all my CBN tooling is but ugly and it works looks like we have a half-decent job joint looks really bad ugly you have the large chunk of CBN on top there and I will just shape it on the diamond wheel and rough shape of the DCM t insert so we can put it in an index lathe tool and go from there ah as with all material stepper grinding of a diamond twill cbn will probably kill you so I'm using dust extraction [Music] okay there we go we got our beautiful CBN insert almost to shape of course this is thicker than a regular DCM t insert but you just have to adjust your height on the tool to get it working now we change to a finer vu you laddie forty if you wanted to do a very good job you could make and holder for the insert and do a machine grind on it but I find that most of the time off hand grinding it's good enough so we start by grinding the top cleaning it up then we're going to grab the sides always with the grinding wheel cutting into the cutting edge always the wheel spins like this and we're always grinding into the cutting edge that's also the reason why for the second side you will see me going over to this side and holding it very awkwardly from from behind okay now yes as we have ground our beautiful ugly insert we'll have to put a tiny tiny edge break on the cutting edges five degree negative 10 degree negative something like that so roughly like like this and like this first side like this so we're again grinding into the cutting wheel and for the second side I'm switching over to the back side of the grinder and try to get it yeah that works okay okay try to get a close-up it looks really not very good at grinding this insert with the hands around the camera it's not the easiest thing but you can see this is the edge break that I put on with about 15 degree same on this side here you can also see that on the insert I scavenged the CBN from it's already a sandwich construction you have two CBN and it's bonded somehow in I don't know how to piece of steel you can also if you have a regular regular CBN CBN turning insert like this strike on shape here instead of removing the CBN and just putting the cbn back on another carrier you can take the whole insert and silver solder that onto a body that that works especially if you're making a large turning tool boring bar threading tool whatever and as I can see when you buy a cbn insert they give you really one cutting edge that's one so yeah they're expensive so I first finish on the grind on my insert is okay it could be better Robin uses a dime and a ceramic black lab with one micron diamond but this will have to do for now let's go to life and give it a shot you okay got a nice high quality very dull phrasal high-speed steel and Miller here of a rock-hard shank we even have an interrupted cut so we will see what happens okay I was running one millimeter depth of cut on the second cut and the CBN could not stand interrupt that cut of cutting through D a well done flat here but until it got there it kept a beautiful chip you have to admit that it really cut very nice it's high speed steel it's 60 something Rockwell hard so it's not a big deal because we can just touch up this front edge and go on so I think that goes to show that it can regrind CBN tooling re repurpose CBN tooling on a very with relatively low amount of tooling you need something to silver solder map torch or even better oxy-fuel and you need a diamond wheel that's reasonably fine preferably a diamond lab if you have one but even with a d40 diamond wheel you get really far okay here are the parts that we just made or finished main thing i want to show is the hard turning with the cbn tooling and also the very simple tools that you can use to work on very hard materials to finish size a bore and yeah just do some machining on those larger parts of this forming forming tool forming die set these are one 2311 tool steel which is something like age 13 I think and these will be plasma and nitrite it I didn't want to go through the trouble of hardening these and hard turning these because they do not need to be as hard as as the Eternals here they just need to be hard and some of the fit surfaces like this one here needs to be polished after hardening or plasma nitriding plasma nitriding is a process that gifts almost like a case hardening with relatively large depth and doesn't change dimensions at all an IT 7 class tolerance field will not change during plasma nitriding at least that's what the guy from the nitriding place told me we will see when these parts come back I got the permission to show this tool but absolutely not the part that are going to be made with this I can show something with a dummy part so once I get the parts back from plasma nitriding and I made all the accessory parts and I put in the Belleville washers disc springs these are some serious disc springs there's some force involved then I will put it all together and and show you how this works it's quite ingenious I didn't design this of course so yeah but I should I won't just to show you the basic principles with a simple lamp like this the hard turning and stuff like that hope you enjoy it thank you all for watching and see you next time [Music]

Channel: Stefan Gotteswinter

Views: 78,531

Rating: 4.9749117 out of 5

Keywords: hardturning, lapping, hartdrehen, hartbearbeitung, läppen, honen, cbn, silberhartlot, silver solder, silversolder, brazing, braze, emco, super 11, emco super 11

Id: o6UeWV_TRuc

Length: 50min 14sec (3014 seconds)

Published: Sun Jul 28 2019