Splinedrive coupler - Toolgrinding and Slotting

and welcome back to this old basement what you see here are two Drive shafts this is a project for a friend so this is no customer work what he wants me to do is to make a coupler - that goes over the spline drive and couple stones two shafts together so we will machine one out of 41 40 and commercial he treats steel and already has about 1200 Newton per square millimeter of tensile strength and use the mill to slot the profile of the spline drive into it and how to figure out the profile and grind the tool etc etc that's all in this video here we have the blind-driving close up and out of a no other than dowel pin I ground me a sixty degree point I looked up spline spline drive profiles and usually they are 60 degree included angles so you make this pin to check it as you can see against the light of my my desk lamp behind it this makes pretty good contact but if you look on the right side for contacts the wall of the gear tooth the side of the gear tooth you can see that it contacts only in the center and not above or below that tells me either this is machine not very good or at an end the lute profile involute gear style profile I could online not find if these axles have an end the lute or a straight spline could figure it out just goes to show there can be more to such a drive than just straight wall just to break it down again normal a spline drive looks like this and it has like 60-degree included angle straight straight sides on the teeth the envelope profile looks more like more like this and once again I'm I'm far from an expert on this I'm figuring this out as I go so let's say you have a circle that magically appeared on here and you take your you're in volute drawing instrument which is a string with a knot in it and you poke your pens really not and you get some tension and when we start to draw the the court or the string will unwrap and that will create the envelope curve there you go that's our end volute involute that's by the way also how guilty for are the signed like on a spur gear it starts out almost square then it goes off into this just long curve this is not a continuous radius this is like a spline like a Bezier curve on MCAT and I'm pretty sure that the splines on this are like this I talked to my friend to make long story short but we'll ignore this and we'll just the six cut a 60-degree profile as far as I can tell the 60-degree profile hits on this teef basically here on center of the teeth so should be good if we add a little bit of force and elastic deformation it will make very good contact I'm not very worried about that as I said we're not going to make a science fair project out of this but I wanted to get the rough idea how to do this out of the way okay now we have kind of figured out the profile of this this spline here we need to figure out how our tool needs to be shaped the 60 degrees are obviously because that that's what we checked by with the 60 degree pin that's in all honesty way good enough for this purpose and now we need the width of the teeth on on the tip here that's the smallest dimension that's what we're going to grind on the tool and we can measure that close enough with a pair of calipers it measures 1 of 105 millimeters I will grind it to one millimeter just to give a little bit of head clearance okay morover at the debate grinder I found myself a piece of 8 millimeter high speed steel round holding in a collet everything is set to zero right now up here the dividing head this joint in this joint this is all 0 first we want to grind the triangular profile of the cutter preferably on center so we start by rotating this in minus 30 degree direction that's the first side of our triangle today I'm using a CBN grinding wheel this is a C 125 grit reasonably fine but not so fine it's it's slow to grind it's it's still a relatively aggressive wheel and right now we're just concerned with removing most of the material we precision our Birkhead in a way we can use it always always do a little bit of a try run we need to cut 16 millimeters deep so we will grind a little bit deeper and go for it I have my best expression here just to keep the majority of the grinding dust away [Laughter] just to show you the progress of my grind I'm grinding the two flats alternating always moving it like this and then 60 degrees over six degrees back and that way my profile stays on center that's very useful if you're slotting tools are our ground to be on centerline because then you can use the spindle of the mill to Center on your part and you're good to go without many problems but we're getting there getting relatively hot that already has a nice golden color but I speed still is not really affected by that you saw me use this here this is a dressing stick to clear out the CBN wheel once it gets clogged up like this that happens when you grind too hard and too aggressive into a CBN wheel happens usually kill me on a manual machine and like a tone pallet rounder surface grinder not that much of a problem these are aluminum oxide sticks they come in different grits the 240 grit suitable for for this kind of for this grit of CBN wheel usually when you buy these you will find a chart let's say they'll tell you the grit you need for your will yeah use these on diamond wheels and CBN wheels and those are not actually for shaping the wheel those are only to room to to to break to break down the binder surrounding the CBN or diamond grit and that prevents the wheel from cutting freely so this is only to make the cut the wheel cut nice and aggressive and relatively cool okay now I can see the overall profile I cut nice triangular 60-degree shape next I will remove quite a bit of material here so I don't have to grind a relief in a frontal relief angle all the way up to there and I will do the same on the sides too so basically what I'm going to do is but from here to here I will grind all this back about 0.2 0.3 millimeters same on this side and also on the front here on the front probably even a bit more doesn't matter that much I do this so I do not have to grind a relief angle over the whole length of the tool and weaken it that way relief angle over the whole length usually tends to create a very thin tool back here and that's bad because it's fragile so let's go back and the way we grind this is we'll just move it here plunge in do our motion plunge a little bit even move it until we're satisfied with what we get okay that's a relief grind on first side as you can see nothing spectacular now we do the same on this side there we go that's a relief grind the smoking Hawk now we go for her this side but also quite a bit of relief grind here now we have this shape already starts to look like a slotting tool next we will grind the side relief very little only but we need it otherwise the tool tends to rub on this face once the cup gets a little bit deeper so better put a little bit of relief in there too right the relief we use this joint here but we can only go up 2-0 degrees or 90 depending in which direction you're thinking and that's the problem so we pull this pin down here so the pin that can be pulled and also locked open but in this case we only need to pull it this by the way also the stop for for this adjustment here to set your 90 you loosen this small set screw here and then you can rotate the stop the stop pin if eccentric and when once you get a small wrench on this hex in here you can adjust your zero and the way do you get your zeroes you clamp a piece of round stock in here you grind a flat you mic both ends and then you adjust your stop pin until the flat is on both ends of your test bar the same with once you have grounded so that was the 30-second rundown how to adjust your d-pad grinder square and we'll just put about one and a half to two degrees off back rake on this tool no need for crazy amount of just [Applause] now return it back to ninety-degree would take care of this front edge here and would grind this until we get our one millimeter whiff of cut okay double-checking yeah that's pretty good that's very close to one millimeter last step is to grind the front rake otherwise this would be a serial degree tool and the cutting forces would be reasonably high so that's turned us set up for grinding the front front rake of the tool I have it set to seven grease down here so the whole head is tilted back a little bit and this is oriented so that cutting edge the narrow part of our tool is pointing straight up and I will just feed it into the wheel until we clean up all the way to the cutting edge I'm grinding that way because the grinding work cuts into the steel that way and we don't get a horrendous burr the drawback on this setup is a drawback on this setup is that I can it's hard to get the nozzle of the vacuum cleaner in there okay here is the tool fresh off the crying wheel we'll take a closer look on the bench in a second okay we're back at the bench I took the high speed steel blank I cut off the back with an angle grinder chamfer and I put a shaft collar on it a split ring collar and this is just to take up the axial forces I'm holding slowing tools in and more steeper to Kaulitz and the axial forces will over time drive the tool it deeper and deeper into the collar and I don't want that so I put the split ring call it collar here and this takes all the axial forces we have our 60-degree included angle between here and here this is all relieved and we have about one and a half degree of back taper on these two surfaces it's kind of blending in to the relief area here here you can see the blend lines a little bit better here here the relief is a little bit deeper and I ground Faridah up the shank so I have a flat here that I can use to indicate the tool so it's oriented correctly about seven degrees of back taper here back rake to make cutting edge action positive so last thing to do is to set up a test piece on the mill and cut cut it to see if or if or all our assumptions that we took and that was quite a lot of assumptions if they all match up and if they don't match up I will just edit it out so now if my rotary table on the mill I'm not using the dividing head because the binding had inverted position has just built up a lot of unnecessary height for vertical shaft work the rotary table is in my opinion the preferable tool so after the street chop centered on the rotary table and I have two spindle of the mill Center on my test piece this is just a piece of aluminum blowers to the correct size and you might notice I'm I'm using not my usual indicator holder this is the indicator holder that I'm normally using but I saw a lot of people use something like these this is a small no garm this is an articulating arm that has ball joints and people seem to like these for centering but I played with it a little bit and I have to say I don't like it it has a few degrees of freedom too much if you start out on a bore you have no idea where you are and it's very easy to get it so far off set to the side that your measurements get almost meaningless so not entirely sure if I like this I'm I'm very sure I will be going back to my my own design or my - to my own indicator holder so next we bring this thing in this is a 3d printed spindle clamp there's large diameter clamps around the quill and the small diameter clamps around the spindle flex your design two screws pushing in it's not D not not the F not the perfect design indicating the tool it's low on this side and high on this side so we we tweak it a little bit okay that's that's within almost 10 micron it's a little bit low here still yeah that's that's good enough now we can clamp the spindle you okay I'm basically done with the test piece I have one more to cut then we can do a test fit as for depth of cut we start at point two millimeters for the first cut as we know first cut is always the deepest and then I progressively go smaller the last cups are about 50 microns there we go that's our profile let's move the table out and see if we can get the shaft in there what a wonderful profile looks really really good the only problem is I'm a little bit too stupid to count to 20 or in this case to 21 the spline profile on the shaft does have 21 teeth not 20 helps if you count carefully so this goes in my my shelf of shame and I will cut a new test piece and repeat with 21 I got a second test piece this time with 21 teeth and when I take one of the axles it fits it's a tiny bit loose a little bit of rotational plane not much but the problem is these parts are not to die components the other axle which has the same profile as a Matt tight fit I could assemble it by it by heating this a little bit or pawning it and with a hammer but this is this is almost a perfect fit a little bit looser than this and I would be happy the other one is in my mind too loose but we're on were on the right track I will slot both sides of the coupler I'm making to match one of the shafts so it will have a direction that it will be mounted but I'm fairly happy I just came out next off to the lathe and preparing the blank for the real part [Music] [Music] [Music] first site board board to the ID chamfort chamfered larger than the final diameter of the of the spline drive so there's nice leaden and ionic at the the end of the bore with this piece of chunk tool made this long time ago for for something else there's a piece of drill rod and it just silver soldered a DCM to9 carbide insert to the end and kind of grinded it into shape to do it on the cut works surprisingly well let's pour the other side I recently bought an ice core DF multi multi-purpose tool these are these are inserted drilled these can drill into solid stock can also do ID boring facing from the inside out OD turning behind the center of rotation on the leaf or upside down and there are also grooving inserts for them to do on the cuts quite a versatile tool very expensive if you buy them new I bought it on ebay for next to nothing and I also got the inserts these are special inserts axe CMT or something like that not like that also on eBay too expensive to buy new at the moment but it's a nice short and very rigid boring tool if you want to drill and to solid with these you need at least compressed and compressed air through the tool or better coolant through the tool otherwise that chips pack up in this area here and you don't get rid of them but for boring and work quite nice without [Music] while at least at least a serviceable finish it's really not that great but due to the fact that the inserts have a relatively large edge radius and corner radius they're tough they're really tough hence you can use them as a drill now we go for the funny tool and this will be almost impossible to film for me I touched a tool here in the end of the part throughout the Dro you'll go to the inside of the bore and that just make a little scratch and check my ID that's 15 5 and my tool is already calibrated to 55 I can go down to final depth 16 millimeters and move out to 17 point two millimeters on the diameter off the AFT on the cut and yes this really will make for great with you because you can't see a thing okay there we go and as you see by the chipster two cuts really well and the sturdy construction of the tool allows for nice chatter free cut some people always have problems with on the cutting end its I had to I really have problems with London cutting IDs but never trick is really go reasonably slow on the RPM feed the tool side actually cuts and does not drop and design your tool to be as rigid as seemingly possible I kept I kept the the spline profile took me two tries to get a nice fit on the loser of the two chefs and when we go here with the spline profile it it barely goes in and it will need assembly with a soft faced hammer but I talked to my friend and he said he told me he can he can assemble the whole part as once in one piece so assembly with a hammer is not a problem they looked closely on to the spline profile on these shafts and these are not milled these are formed without creating a chip there are either suede like in a like like a tool for a to switch the end off of cables crimp anchor to like a crimp on connector and then probably the OD was machined so these teeth are not crazy precise and for that reason I'm going with the profile on my coupler a little bit on the tight side and still be able to assemble it compared to making it to lose and rattling it around when it rattles around during operation it will where it will create contact for corrosion that's that's the brown braided and kind of oxidized material that you find on on for example 40 taper tooling that has run really really hard in a milling machine for a long time then you take tool out of the spend and you get this brown debris that that's part of your spindle and your tool holder that abraded Google contact corrosion for that matter and in German we call it Pathan's ghost that like like close fit rust okay here is another view into the profile you can see the teeth that we cut and down here this is the undercut this is where the tool once it has cut the the actual tooth or in fact it cuts the tooth gaps and two tooth gaps format tooth in between this down here and Akkad is word a tool drops free left of the cut once once it leaves the material and I set my depth stop so it does not bump into the the lower wall of the undercut that would that would create a lot of wear on the tool just just a lot of strain and stress that you don't need so let's get this out here I'm quite pleased tell just came out this really looks quite nice okay our rotary table has a has a ratio one to ninety ninety and the number of teeth we want to cut is 21 not twenty so we put this in the fraction 90 by 21 and there is already a ratio between the index plate we need and the number of holes we have to go on a 21 whole index plate we would have to go 90 holes 90 holes of course is like that's four turns four turns equals 48 holes four times 21 is this 84 then we have six holes that's the difference between the 48 the 84 and 90 cents huh we could shorten this fraction for example divided by 3 or shorten it by 3 I would give us 30 divided by because 90 divided by 3 is 30 and 21 divided by 3 is 7 that would give us 37th this is purely hypothetical because I don't have a 7 whole index plate but let's play with this never give us 4 turns 4 times 7 is 28 28 holds and the rest the difference between this this would be 2 holes so but we cannot we can't do this because we don't have a 7 whole index plate but we have 21 whole index plate this here so that means we can do it like this four terms and six holes I talked earlier but my theory of this being an involute spline profile I'm not too sure about that might be but it could also be that these profiles are just super shitty mate as you can see the the turning work on it is quite rough this is quite rough there's a bearing seat there's this machine quite nice but the the spline profile here is really gnarly and it's not milled or hopped because there is no lead out here if if this profile was hopped or or milled we would have lead out here from from a circular cutter but it ends a prompt in a sharp-edged and my theory is that that these are and these get formed some some way of swaging or press forming almost like forging and then they just turn the OD because when you press form this the material will go somewhere it what go above the OD then you turn the OD to clean it up then you have an induction hardened and you're good to go so that's my theory why these are so so nasty and so different especially these are very different fit I guess my my theory about the involute contour was wrong but I will still leave it in the video just so I can show how to draw an involute and my thinking process behind working on something like this I usually don't work on parts that have that are really part but these go as far as I know in a model and a large scale truck model so this is quite a new experience for me it's against the DoD isn't even finished on these these are there's a still mill scale surface they just finished the dissection here and I'll tear they do the same and here the profiles even worse this is a course of spline profile and this reel looks really gnarly but I think that the site is used already part is done I just threw it quickly in the ultrasonic cleaner to get rid of all the cutting oil on it polish the outside slightly with some scotch brite so I hope this was interesting goes to show that the milling machine can do more than just milling I should slotting now for numerous times but this this time was a good opportunity to show also grinding such a tool on the debate ground so I hope it was reasonably interesting thank you all for watching you next time [Music]

Channel: Stefan Gotteswinter

Views: 58,479

Rating: 4.9749708 out of 5

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Id: vDa3hwv7_8s

Length: 40min 8sec (2408 seconds)

Published: Sun Mar 01 2020