Building the Titan .60 Glow Plug Engine #3

[Applause] hey good day it's crazy thanks for joining me in the workshop today now today's sticker came to me all the way from germany a place called geraldstein and was sent to me by christian hymns now christian is a german model engineer as you probably guessed and he's building a beautiful little steam locomotive it's a model an accurate scale model of a french engine called a decarval or the corbel and it's an o2ot locomotive now the french classification system for locomotives is different to england in france they count the number of axles rather than the number of wheels but essentially it's a four-wheel narrow gauge steam locomotive and like everything made in germany the craftsmanship is extremely good so please check him out i'll put his link up above here so if you have any interest at all in steam locomotives or engines in general it's worth checking out now speaking of engines today is episode three of the titan glow plug engine build and this thing has just gone off couldn't believe the number of views that i got on the first episode the second episode's going the same way and it's amazing how many people are interested in this build so that's a good thing for me good thing for you but let's head over to the bench and have a look at what we're doing today in the last episode we got through machining most of the crank case now there were still a few items to be done one of them is machining the flat face on top of the crankcase where the cylinder will be bolted and we also have to do the exhaust port so those two things are happening today we're also going to machine up the bronze bush that carries the crankshaft now speaking of the crankshaft this is where i have to admit to you something quite painful it's true i've been living a lie i know you're thinking does this look like the face of a man who would lie well how do you explain this that's right two crankshafts now if you look at this now you can see there's an obvious difference between these two crankshafts and this is the one that i did in episode one now i machined this up from the stock that was supplied in the kit and i was totally happy with the way it turned out everything was spot-on for diameter thread turned out great all of the eccentric turning at this end went well and i was totally happy with it and to be fair this crankshaft here the one in episode 1 was an accurate representation of the drawing that i had done the only problem is that the drawing was wrong now this is not the drawing that i was supplied with i went ahead and actually modeled the crankshaft in my cad program and i did that so that i could get dual measurements for all of the cylindrical turning that had to be done on the main part of the shaft here because i worked mainly in metric and i also could rearrange the dimensions so they were all positioned from one end of the crankshaft unfortunately i overlooked one single dimension now anybody who's done any work with cad drawing would know that leaving an unconstrained dimension in a model is almost a sackable and that's exactly what i did so this one dimension here from this shoulder up to the back of the crank disc here i drawn a line but i hadn't put a dimension on it i'd dimension everything else and of course you can make the model and it looks fantastic now it was only after i had machined up the crank case that i put this through the the board of the crankcase and realized that this section here which is where the prop driver will go was in the wrong place and feeling like an absolute idiot i decided that it had to be made over again now as it turned out i had some 4140 steel to make the second crankshaft now this one is 1018 this one's 41.40 4140 is a much better steel for this application and having done the first one i knew the workflow for the second one and it turned out equally as good probably better actually i think i did a much better job on the thread and i was able to get this section of the uh the crankshaft more parallel this one has a very very slight taper in it this one's pretty much spot on so doing a second time over was probably a good thing and i also went ahead and actually made a second drawing so this one here shows the entire engine and cross section and this allowed me to verify that i had the crankshaft right so this is the prop driver and it needs to be clear of the end of the crankcase casting by a couple of hundredths of a millimeter and i can zoom in on this drawing and i can see that i have that clearance there so yeah lesson learned it's probably a good idea to actually model all of the parts and check your assembly before you go ahead like a mug and machine the wrong part so there you go i've admitted on camera that i make mistakes i mean you all know that and i'm pretty sure that uh we all do this you know it's just that when you commit yourself to making a youtube series and things go wrong you everyone gets to see it so that's what's happened anyway let's head over to the milling machine and let's get busy with the crankcase casting now i know i did this operation in the last video and all i can say is i screwed up somewhere maths was never my strong point and when i was offsetting from this piece of pvc something went wrong and it wasn't until later when i took it out of the bias and checked it carefully i realized that i'm about two millimeters too high on the surface here so it's a mistake but in a good way it's recoverable so um the other thing that alerted me was i looked at the drawing and this uh this surface of the exhaust port here is meant to be flush with this surface here which is where the cooling fins will bolt down so um that's what made me think i've made a mistake somewhere anyway i'm going to do this now with my fly cutter and i'll check it with the depth micrometer just to be sure i've got it right [Music] that's pretty heavy cut for a fly cutter but it means that the last cut i do will be a bit bit lighter and leave a better finish [Music] [Music] okay well that's exactly the same as the drawing now that's how it's meant to look so let's go ahead and get this exhaust port machined out the last operation i need to do on the crankcase at this point is to machine the exhaust port now i'm sure you've realized by now that there are very few reference surfaces on this casting that i can access when i go to do things like setting up for this operation here so what i've got is a steel plug fitting in that bore there and this is going to allow me to indicate off both sides of that bore and i can then step in the correct distance from this face here and start machining out the port now the port has to be 3 8 of an inch wide and there are dimensions shown in the drawing for the length of the port and it needs to be split in the middle as you see later and the other thing is that it's just an awkward thing to hold and it's awkward to set up but what i've been able to do is to indicate uh vertically down this plan here and hopefully it's not going to let me down but there's the indicator sweeping down that face there and showing zero and i should be able to sweep across that way so that is all aligned the way i want it so what we'll do next we'll we'll indicate in the steel plug and then it can come out we can get rid of it it's just to find the center of the ball [Applause] okay i'm going to set the half function on the y-axis on my dro and we'll find our way to the center of that ball okay so i'm going to lock the y-axis there so now what we'll do is come in and touch off against this surface here [Music] okay so now we're touched off here and we're going to offset the correct distance to the center of the exhaust port so what i've got here is a 3 8 slot drill and i've got everything lined up i've done my offset from this face here to get the center of the exhaust port and i've offset from the center of the port to the very end and i can take that steel plug out now and then what we can do is just lower the quill now i've set my depth stop so it'll go to the correct distance and this first part of the slot will go all the way across and then we've got to do two smaller slots either side of center leaving a sort of a rib in the center which is used for an anchor point for one of the cylinder head studs so we're just going to plunge this and then advance the table toward me just taking small bites as we go across and then we'll do a sweep to finish off now i'm extremely nervous about this i've gotten this far without too many mishaps and you know this is probably the last major operation to happen on this so i really wanted to go right and i've thought about all the possibilities and go wrong i think i've covered them all but now what can we do uh [Music] [Music] okay sort of hoping that looks right now we're gonna sweep back the other way now with the cutter held at its correct depth so i switched over to the ball noise end mill and the two short slots in our 7.3 either side of what will be the center and up to 14.28 which should be the end of this uh original pocket here and the cutter should break through into the bore of the cylinder so again i've set the knee to the correct depth set my death stop and i'm just going to use the quill to take successive cuts down to that depth and then we'll clean it up in one last pass again very nervous about this this first cut should be just to the uh to this side of center and then we're coming out all the way to the end of the pocket so okay that seemed to be okay now i'm going to do the other one off camera or i might shift the camera we'll do the last one and then we'll come back and have a look at that but because that then is done and we can move on to another part of the engine well i think i can breathe a sigh of relief now having done most the major operations on this crankcase casting and just remember this is the only part that i can't remake and cutting this exhaust port was giving me lots of nightmares i had to do lots of conversions from imperial to metric dimensions and you can see i've got notes all over here i've got another page here i've been scribbling down dimensions and part of the problem with these drawings is it doesn't always give you functional dimensions so for example with the the length of these ports it just gives you the distance from one circular end to the other circular end point what you really want is the distance from center to center and because i'm doing the conversions from imperial to metric there's lots of places where things can go wrong so i double checked and triple checked my measurements and i hope i got it right but as you can see before errors do creep in but we were able to recover from that one the other thing that's worth noting is that this exhaust port is really not a a really accurate part of the timing to do with the engine that all happens with this part which is the cylinder liner now it will have some windows cut in the outside of that liner and they allow the piston to get the timing correct for the the transfer of gases from the crankcase to the top of the combustion chamber so this is the part that needs to be super accurate this is really just like a um an escape path for the hot gases that's all all right now the next step is to make the the bushing that goes inside the crankcase bore and that's a sort of a bronze material we'll go and do that on the lathe now and let's hope we can get this part ready and finished and then i'm going to have a go at actually lapping the crank shaft so we'll ream this to size and not touch it and then we'll try to get the crankshaft to size by doing an external lapping operation the material we're using for this crankshaft bushing is a leaded bronze so that's an alloy of copper zinc tin and about two percent lead it's supposed to make a nice wear resistant material for this bushing so let's go ahead and get this baby machined [Music] [Applause] [Music] [Applause] [Music] [Applause] [Music] [Applause] so [Applause] [Music] [Applause] so [Music] got a feeling that moved in the chuck just gonna face it again just to be sure [Music] [Applause] [Music] [Applause] [Music] okay so i'm going to drill this just under size and then bore it and then we're going to ream at 9 16. [Music] [Applause] [Music] i don't know if you saw that but that drill bit grabbed just after it got started this is a very sharp 12 millimeter drill bit and the problem with these is that they have a fair amount of rake on the cutting edge and with brass and bronze materials like that they really need to have zero or negative break and that's what happens it can quite often pull the drill bit into the stock and if you don't have it really tight in your tailstock chuck it'll just either pull the chuck out or pull the drill bit out but luckily i got away with that [Music] [Applause] [Music] it's just a preliminary cut just to make the ball parallel and i want to go to 14.1 which is just slightly undersized and the rim will do the rest so i got about two mil to come out of there [Music] [Applause] [Music] [Applause] well that was the last cut that i dare to do with the boring bar and see the reamer is now starting to enter that hole so it's going to be just the last three fourth hour taken off by the reamer and after we've pressed this into the crankcase bore we'll ream it again just in case uh pressure on inserting that into the ball has collapsed it in any way but i doubt that's going to happen okay i've got the spindle set to a fairly low speed low rpm and i've got the tail sock loose and we're just going to slide the tailstock in and out again in one action and i'm doing this dry with no coolant or lubricant it should be self lubricating [Applause] so and that should be it all right uh that's what i was hoping for so that crank shaft is just barely entering and that means that i can afford to lap some material off the crankshaft to make it a really nice fit so that's worked out well so we're going to face and chamfer both ends now bring it back to the correct length and then mount it on a mandrel to do the rest [Music] dad [Music] [Music] [Music] [Applause] [Music] [Applause] [Music] all right so we've got to take this out measure its length and work out how much material still needs to come off and we're going to leave this a couple of hour oversized [Music] [Applause] [Music] that should be machined to length now plus couple of hour extra which will be trimmed off later and we can mount this on a mandrel now finish off the outside right this is a steel mandrel that i machined up and it's been in this er40 collet chuck and i haven't taken it out and i also marked the first end of the brass bushing that i machined so this one should be absolutely square to the bore that we reamed the other end isn't so important and we can slide it on there and then there's an m6 thread and i can use this little uh clamp to hold that on there now this um steel washer here is too big but it doesn't matter i'll just machine that down as we go and what we need to do now is to machine this so that it's a a very slight interference fit in the casting that we've already made and i've made up a like a gauge so i can check our progress as we go but once again this is one of those really critical operations if this is loose in any way at all it's sort of ruined if it's too tight and we press it in we can crack the casting so really have to get this right so if i don't talk too much it's because i'm concentrating and i just saw the evidence which tells me how much this slid when i was doing the initial drilling so that was just my bad i didn't tighten the chuck enough but as it turned out didn't matter all right so let's get this cleaned up [Music] so this diameter here i'm just getting this set now this will become the diameter of the the boss on the end of this um this bushing so it's not so critical but i'll get it right oh that's great it's already under size so this is meant to finish at three quarters i'm guessing this was sort of a nominal three quarters diameter um but like i say it's not that critical i think i'll just clean it up and that's all it's about just under a thou under it's nominal size so [Music] now just just barely clean that up okay now this is the this is the important one we need to get this absolutely dead nuts right [Applause] that's a better finish yeah five [Music] now i'm just second guessing here that that should not go in there you can see it sort of once gets started but it won't quite go so i'm happy that that's right [Music] all right that should be it [Music] okay so this is how this should work the bush should be a really snug almost a press fit in the bore of that casting there and what i'll eventually do is heat this casting up and then the bush should just drop through and then as the casting cools it should shrink back around that bush there now the little raised section that we left on the end of the bush there is what the end of the crankshaft disc will run against so this surface here the only contact between the bush and that disc is just that raised land there so that needs to remain lubricated while the engine is running and of course that should not fit in there yet so we're going to lap this section here to get everything to fit correctly and uh bob's your uncle right so i'm going to wind this episode up here now let's uh let's head over to the bench and wrap this up okay i hope you enjoyed that today in the next episode we're going to go ahead and we're going to make a lap for the crankshaft now this is what i'll be making it from it's a piece of 6061 aluminium it's a type of lap that i saw on robin renzetti's channel might be as good as his but it'll do the job and we're going to try to get the last couple of tenths off the diameter of that shaft there and improve the surface finish and then we should be able to allow this to run with a nice running fit in that bronze bush there now also uh some people have asked why there are no mounting logs on the side of the crankcase and that's because this engine has what they call a bulkhead mount and that's this casting here that forms the seal in the back of the crankcase and we'll also have three holes drilled in it so you can screw the engine direct to the bulkhead of the model aircraft so if we get time we'll make that part as well thankfully this is a pretty straightforward part and i'm hoping that the the worst of this engine is behind me now still got a couple of challenging parts to come that's going to be the piston and getting a really good fit inside the cylinder liner but hopefully by then i'll be on top of this lapping business and we can make that happen so that's it for today thanks for joining me i'll check you on the next video and thanks for watching getting quite the collection of stickers here you know that's great

Channel: Mark Presling

Views: 60,744

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Id: XalJmvZD2uY

Length: 31min 39sec (1899 seconds)

Published: Fri Sep 24 2021