Fixing the MemoryWriter 6040 floppy drive with Solvespace

I have a new Memorex 64t word processor from 1987 but you all knew that because you saw my last video well while I was fiddling with it this happened so let's take a look at that floppy drive on the bench so the first thing to do of course is to get at the drive I have opened this before so yeah this should not be a long video most likely all that's happened is that one of the belts has gone however this is a self- ejecting floppy drive you don't push the button to eject the disc the computer operates a motor and that does it and I've only ever seen these on Apple Max and Sun workstations so it be interesting to take a look at this the mechanism which has failed is in fact the eject mechanism so here's the drive and I can already see a few interesting features one of which is that it uses the standard connector for a floppy Drive which is a 34 pin IDC connector except that floppy drives normally have a separate connector for the power which goes here and this is getting its power from the floppy drive cable so it can't be the standard pinout not to mention that the eject mechanism needs to be connected up as well the other thing might be a little hard to spot but these surface mount components are mostly cylindrical rather than cuboid I know this floppy Drive probably dates to 1987 the same vintage as the rest of the machine and I know surface mount stuff was around before then so I wonder what was going on here I've never seen these before but the stuff I want is on the other side so let's just spudge open this protective case and see what's inside it looks like a floppy drive this looks very much like the other floppy drives I've seen on this side this is is a PCB mounted motor for running the spindle and in there is the flywheel this is a steeper motor to move the head forwards and backwards this is new this must be the motor to operate the eject mechanism and that's the thing that's failed because the spindle motor is PCB mounted there is no belt there it's a direct drive this to the spin indle which is under here so whatever's gone wrong is over here now I do want to be careful because I have wrecked floppy Drives By removing the wrong screw there's some subtle calibration in the position of the head and if that goes wrong it's a job trying to fix it so I think this is pretty much the same mechanism as any other 3 and 1/2 in drive if I insert a disc then this thing here here slides the hatch open and then when it goes all the way in the heads clamped down onto the magnetic media inside and in fact here this is where the eject button would go so how is the mechanized thing working there are gears in there this module here seems to be the whole eject mechanism so will it come off not with that screwdriver so what do we see yeah that's quite interesting the motor clearly winds this Cog around this has a projection here that sticks down here into this thing if I insert the disc you see that moves back that's attached to the eject button so if I pull here the dis ejects and in fact it's directly attached so why isn't it operating the mechanism it looks like the motor is just clipped in so I might be able to just unclip it and I can immediately see that while this this thing has a cog there is nothing in here for the Cog to actually connect to so I think that a little plastic gear inside has stripped its plastic do I dare try to uncp this back plate or will something go spring and it'll lose cogs all over the place this is is awkward I need to push the clip back and push the plate up at the same time there we go and that reveals gears and I can see the precise problem so hopefully this one should just lift off it does this gear has stripped you can see the Gap here where the teeth should go oh boy what am I going to do to fix that if I CL push the motor back up there you can see it meshing with the motor I keep turning the motor and now it doesn't turn the Cog anymore let's make a gear wheel what you're looking at here is the gear which I've scanned on my flatbed scanner which is a very old trick for getting high resolution images of things you may notice that there are fewer teeth on this than there were previously because this thing is falling apart and just handling it made some of the teeth fall off in fact after I scanned it the whole thing broke into three pieces so that's nice so what I'm going to do is rotate this I put the origin in the center here and I am going to rotate it until the teeth are more or less horizontal let's turn on some guides like so that will do okay this will then allow me to crop it fairly tightly to the edges of the teeth this gives me the outer diameter of the wheel like so and commit okay and this is giving me an image which is 440x 437 which is good enough now I scanned this at 1200 DPI so 1 1200 dots per inch in millimet is 47.24 therefore 440 pixels is 9.32 MM across save and let's go over to our 3D modeler my favorite 3D modeler is this one called solv space which is a parametric editor so what I'm going to do is load the image like so now just calculated somewhere inside the mass of logs 9.32

2 is the diameter of the Cog wheel so I can stick a constraint here of 9322 like so and we now have our image of the gear wheel at the correct scale on our work surface so we actually want to put this up near the the origin because we've got the constraint here I now cannot resize the thing but I can grab a corner and rotate it which is not particularly what we want so I'm going to stick a construction line actually I don't need a construction line there if I stick another constraint on these two points to say that it need to be horizontal the thing is now Square so I am going to put a construction line here between this corner and this corner and I'm going to create a point and that point is going to go in the middle of our box here this is close enough to the center of the gear wheel so I can now put another constraint to say that these two should be on top of each other and now we have our image locked at the center of our workspace so let's draw a few circles to give us the size places of things and they're all centered in the middle so we have this Inner Circle here which is the spindle around which the thing rotates so we put that there and we actually want this to be a construction Circle so I've put it into green this means it won't contribute geometry to the model and let's put another Circle here again construction and another another Circle here for the outside of the teeth and in fact our Outer Circle diameter is going to be the same as the diameter of our Cog that we know is93 CM across in fact uh right I cannot put a constraint to say the Outer Circle has to be the same size as this CU this doesn't have a line on it but I can draw a construction line from here to here and now I should be able to say that and that nah I can't say that they're the same so instead I'm going to have to do this a slightly different way if I now stick a point on the circle here and a point on the circle here and also say that these points need to be on this diameter line like so I can then draw an additional construction line between here and here select that and now I can make that the same size as this line right now everything has gone red because there are conflicting constraints CU I still have this constraint here for the diameter so if I delete that and if everything goes back the way it was and you notice that as Circle here is actually overlapping the edges of our image because the image is not quite square but it should be close enough okay so we now have a bunch of reference shapes there's two more things I need to do put set of construction lines from here to here and it's automatically put a vertical constraint on that because I drew the line vertically another one from here to here and in fact let's get rid of that vertical constraint that then allows us to move this line we'll put it to the middle of that tooth and we put that to the middle of that tooth and now I can put a reference angle on that will tell me what the angle is without putting a constraint which is 11.75 so that's going to be 12° between teeth can I convert that to a non reference toggle reference there we go right now that's a constraint so these two lines must be 11.75 de apart and I can actually drag the two like this so we know that actually wants to be 12 like so and let's put the vertical constraint back on this line actually no no I'll leave it like that okay so we now have our image which is just for reference it's not actually going to have anything to do with our final model and a bunch of construction lines which I hope are going to be visible in the screen capture they are quite thin anyway so the way solv space works is you build your model up in layers we have here our base layer which I'm actually going to call rename [Applause] more references everything here is a construction line so this is not going to contribute anything to the final model we're now going to actually start building stuff so the way I do that is here it is in 3D with perspective on just to make life easier to see I need to select this and a couple of lines this will then allow me to create a new work plane which it's done so I can refer to my geometry lines in the reference plane let's add a actual geometry Circle arbitary size there select it and our reference Circle they are the same size we now have our first piece of geometry the second piece of geometry is actually going to be the teeth now these teeth look like involute curves sort of my 3D printer is a simple filament printer and I don't think it's capable of reproducing these accurately so I'm actually going to do something else and hope it works so we're going to start here and I'm going to draw a circle of Arc like this going to draw another circle of Arc uh like this and I've connected them together now I actually want to draw a wedge okay so this Inner Circle here is wrong this wants to be another circle of Arc let's put that there centered on the origin this wants to be on this line This wants to be on this line and the diameter wants to be the same as this reference Circle so we now have our Center there we can now draw real lines from there to there and from there to there so we now have more or less an enclosed shape it's not quite right because of this position here yeah let's actually get rid of those and do something slightly different so instead I am going to make a piece of Arc there that corresponds to this piece of the tooth and another piece of Arc there for the top half of the outer part of the tooth and another one here so connect these connect these construction [Music] line that wants to be in the middle this is 90° it's going to want to end on this line actually it's going to want to end here these two are going to be parallel these two are going to be parallel this connects here and parallel these are the same diameter these are the same diameter okay and then this wants to be a this wants to be a quarter Circle so this wants to be on this line here which it doesn't like because that's no longer tangent ah yeah that hasn't worked quite so well so let's just go back to here so let's get rid of that constraint they need to be tangent that one no I didn't want to do that curve curve tangent we want to keep that one Arc line tangent we want to get rid of that one right so that then allows us to bring this down in a more controlled fashion now I can put it on and that will work again on this side we never put on a tangent Arc so I can do that here stick that on like so now it's still not right we want the thing to be symmetrical so I want this line and this line to be the same length like so and in order to position it correctly I'm going to create a point stick it on the this on this Arc and on this Arc so now we are constrained to places where the the point is on this circle here we want the point to be at the centermost position of this Arc the easiest way to do that is to create a construction line from there to the or origin no from there to the origin and place this point on that Arc right so we now have a completely fixed shape it has no it is fully constrained it has no degrees of freedom and it is a solid shape so [Music] extrude I don't care about how far it's extruded so far and now I can wrong one now I can rotate it about this axis and this point rotate change 30 there are too many faces that are flush with each other and the red lines means it's having a bit of problem resolving this I can do that and switch to a different representation that works better so we should now have a gear I don't know whether it'll work because the shape of these is different from the pegs in the original shape here but I believe that my 3D printer will have a much better job of dealing with these than it will with anything longer okay we do need to change how far it is extruded so we need to come up with a length for this so we go back to here and we [Music] load this which I forgot to crop this is a rather dodgy scan I did of a fragment seen from the side it's it's kind of blurred in places because my scanner's depth of field is very poor I used to have a scanner with really good depth of field you could put like complete pcbs on it and it would give you detailed INF Focus images of everything up to a few centimeters away but this should be good enough let's crop that one more time the here select rotate show Green we that's more or less horizontal that should do I'll crop it one more time select like this I'm just using the selection as a measuring tool to about about there and about there I think so this is 61 pixel high so according to our maths that is 1.29 MM thick so stick a constraint on that line of [Music] 1.3 that shrinks a bit and we now have hopefully a properly sized gear wheel now this is only part of it we also need to do the other part so back into and we go to this image this is the top of the gear wheel and you can see here these two big cracks that's from where it was beginning to disintegrate just from handling so again crop actually first I need to rotate it show grid rotate uh put Center in the center and rotate until the these two are horizontal commit crop [Music] to there and there and there and there commit and that has given me an image which is 177 by 178 that's good enough and I'm going to create a work plane actually hang on there's one important thing I've forgotten to do uh over here I can see that there's a one under degrees of freedom that's because I can do this it might be clearer if I there we go so I haven't actually constrained the angle between each of these wedges actually it's easier to see here so you can see how I can change the distance between them in fact I should be able to put these two Corner points if I do that and and that I now have perspective turned off and I'm looking straight down so I should be able to tell it these two points should be on top of each other right it can't quite do that because inaccuracies in the algorithm means they can't put these close enough on top of each other to satisfy the constraints which is a shame because that's the most intuitive way of doing it but instead what I'm going to do is to say that the this angle must be the same as this angle must be the same as this angle I hope that's the right way to do it equal angle yeah okay and that has now popped into position and I now have 0 degrees of freedom so I want to create a new work plane sitting on top of the gear wheel so this is our point point which is the top of the wheel and I'm going to use our original two wedge lines to produce the normal so create work plane like so and now add an image front and this is going to go on top of this and as before we go to and we see that our image is 177 pixels across we go over here and we see that that means that it's 3.75 mm

wide so this line firstly is horizontal secondly is 3.57 75 so there is the there is our our rectangle properly sized and you can see that the circles do more or less match we put our construction line across here as as before and actually while I'm working with that let's just bring it up here create a point point goes in the middle and we want that point and that point to be congruent and there is our reference image placed correctly and as before we draw a a circle for the inside which is a construction geometry and a circle for the outside and we create a point here and a point here these need to be the top of each other these need to be on top of each other we have a construction line across there that needs to be have a construction line there that needs to be the same size as that set that to instruction geometry create another construction line from here to here which is vertical and from here [Music] to oh huh I already have that line so that means the angle between T is 45° which is quite nice we've created all our construction lines our reference lines for this gear wheel so let's create another another work plane there we go this is yet another layer stacked on top of the others hello why does this say it's got one degree of Freedom what can I change this one so let's put that there and I'm just going to see 2 point 21 yeah let's put a dimension constraint 2.2 on it to fix it in place so now it's basically the same process for drawing geometry uh this stuff here is Zed order clashing because my reference image here is congruent with the surface of this gear it's just a reference image so it doesn't actually matter but it is a bit ugly so as is before create cir circle of Arc like that Circle of Arc like that but 90° circle of Arc like that put these on top of each other to connect them that is 90° this is on this line this is also on this line and let's bring this these two are tangent and there we go so a lot of these shapes there are two solutions and solv space will sometimes pick the wrong one it needs a bit of encouragement to get the right one so these are tangent this is on this line this is also on this line these two are the same diameter these two are the same diameter and we should now have our tooth shape it does say air oh right that's because I don't have a closed shape here to work with I can handle that easily enough let's create another piece of Arc down here put that on that line that on that line that On the Origin that wants to be on I have the intermediate steps disabled up here so that this you can see it highlighting is our reference circle on the Bas plane so we want that and that to be the same diameter and that gives us our Inner Circle so piece of geometry there oh I pressed the reference geometry button piece of geometry there and a piece of geometry there and this fills in because it's now well filled and as before reference geometry from there to there create a point put that point on the line and that has now locked that in the center of our that's not right oh yeah this and this need to be the same length there we go so now I can adjust the inner size of the Cog structure so I put that point on our Inner Circle and I want to adjust this to something sensible did I have to do this no I didn't have to do that with the the other set of teeth so why so I did put a horizontal constraint across there so yeah that'll be it okay piece of reference geometry there to there put this on the line and yeah that has fixed it in place but I'm not entirely thrilled because once this has been extruded and rotated there's a actually a concave piece inside which I don't think I want so let's just get rid of that I want this position to just such a point so that there is no backward curve here so I want these curves to be tangent to a line passing through the center point so if I do that and I say that this must be tangent Ah that's worked excellent all right so there we have our teeth for the inner part of the gear and apart from the flickering you can make out that these teeth are actually shorter than the original ones and likewise these teeth are shorter but I'm hoping it will work anyway it will probably need adjustment but we want to [Music] extrude and rotate uh rotate about this line and there are eight of them there we go and let's just drag this a bit here are our original construction lines so we want these two lines to be the same angle as these two lines constrain [Music] angle and it doesn't quite snap into position let's go back to our sketch and if I select these and put a reference angle on 44.8

right that's not right oh I know what's going on uh this is not quite Square therefore this line here is not quite at 45° which is annoying okay let's put another piece of reference geometry there and what that and that to be actually at 45° right now unfortunately we now have to edit this sketch so that this is attached to the other line so this points coincident so that is not actually constrained to be on the line what about this one this is the center of this Arc here and the right this is constrains to be on the line so I delete that constraint I should be able to drag this yeah let's put that on this line that on this line like so probably here as well no those are coincident here's our constraint that point is on that line there we go so put that on that one right there we go and now if I go up to this one it is still not quite matched but that's because my equal angle constraint which is shown here is referring to the wrong lines we go delete that this angle to be the same as this angle equal angle Bingo okay and back here to we look at the side image I want to know how big this bit is it's 80 pixels which is 1.7 mm 1.7 and there is our wedge which is the right size we go to the final layer and here should be our gear now have no idea whether it works but the next step is to 3D print it and see after a lot of work here is the final product and here are all the failed prototypes let me just move that out of the way this took a lot of trial and error to make and I kept having to fiddle with the printer settings on the model you notice that the original here in its several pieces from where it has broken apart has longer teeth than this in fact I did have to change the model to make the teeth longer but if I made them too long then the gear would just bind and not go around this seems to be a reasonable compromise where it actually works although it's not entirely perfect this is one of the better failed ones now I actually had to buy a 0.2 mm nozzle to print this it's a little hard to see on camera but printed with the .4 mm nozzle the shape of the teeth just aren't right and the gear just doesn't work as the little motor Cog turns it binds and the whole thing just jams solid here's the gearbox unit itself I have actually tacked a couple of wires onto the motor terminals so that I can make the motor go around that's running on 5 volts I don't know if that's the right voltage it might a 12vt thing but I'm not going to use more than that so if I place the gear need a little bit of there we go then it's not exactly quiet it's quite rattly that will be probably large tolerances in the teeth but it does actually seem to work if I add the second gear the one that connects it to the rest of the gearbox and then apply power it works I am going to very tentatively add a few drops of light lubricating oil that should do because that gear is pretty rough let's see what this does yeah that sounds way better let's just do one more the 3D printed part is actually porous so the oil will get absorbed into the plas s and then released over time so that should be good right now I just need to put it back together and there is a small problem with that which is this goes on here which is that the ancient plastic Clips have all broken so this thing is not actually held on by anything other than hopes and prayers luckily in the floppy disc drive this goes face down so it doesn't need to be held on by very much once it's installed it should be fine so let's just stick a piece of capan tape over it like that and of course I do need to remove those wires so now I just need to put this thing back on by first plugging it in because there is no clearance and then this thing goes in there and and with luck that should be all there is to it so I suppose I'll go and have to try it and see what happens fun fact this cable is not polarized so I had to look at the pin out to determine which around to put it I'm hoping that the stripe on the cable corresponds to pin one anyway let's try it and see Power well that wasn't a great noise but it did do the right thing so let's try sticking a disc in yeah that noise was horrible but it does work reassembly should be the same as disassembly but backwards that just requires me to remember what it was I did I seem to have four screws left over I hope they weren't important and here it is fully functional and yes I have figured out where the video memory lives so that is done the gear is clearly not perfect it shouldn't be making that noise chances are it'll break sometime in the future I'll make another one and Tinker with the shape a bit the teeth are clearly not quite right but it is at least working for now which allows me to get moving with reverse engineering the typewriter I hope you enjoyed watching me work solvespace I think it's an excellent 3D modeler and I don't know why other people haven't heard of it the next job is to fix the keyboard which is hopelessly ruined by age but that will be in a different video so until then as always I hope you enjoy this video please let me know what you think in the comments and I will see you next time

2025-03-30 15:08

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