Internal Splines (and Hexes Too)

to be honest I've kind of been putting this project off because I'm a little scared of it let me explain how I got into this one there's a little Community ski area near me it's the kind of place that's run by volunteers most weekends they get businesses to sponsor it so it's free to ski it's called Veterans Memorial Recreation Area it's the kind of place that's hard to say no to when they want you to help out so when a friend of mine that's involved there asked if I could cut an internal spline I guess maybe I've been watching too many Russell Knox videos and I said yeah I should be able to do that on the shaper so this is a pump that was donated to them that they want to use for doing a small snow making system the problem is they don't have the coupler to attach the pump to the motor I'm not entirely convinced this motor was ever actually attached to this pump but now I need to make it work the shaft on the pump is a 5 8 hex and the motor has a 15 spline shaft so I just need a coupler to attach those together I should be able to do that all in the shaper but I have some tooling I need to build so foreign this is a random scrap and [Music] [Music] [Music] foreign oh that actually looks like [Music] I've actually got two Taps this size this one seems a little sharper that is just a really big tap to push in there foreign [Music] foreign immediately started walking off to the side a little bit see if we can salvage this I came through pretty close to square to the piece but it's not Square enough for this you know what this is dumb this is probably not going to be the last one of these I make either foreign foreign this thing now I'm grinding it to final size being really careful to take the same amount off of each side in retrospect I probably should have just made it to final size before I hardened it foreign well now I have a tool I can cut internal features with but since that square brooch worked so well decided hey why not make a hex broach and I got this far before I screwed up I set this up with an indicator on it to make sure I wasn't deflecting it when I was clamping it down and cut two sides of it got it right on Dimension here but it's about eight thousandths under on this end what I didn't check was to make sure this was actually sitting straight before I clamped this down but the thing about a brooch like this is really only the last tooth needs to be exactly on Dimension so if I put the last tooth over here it should still be salvageable and I'm just going to go back and make sure that the other four sides of it are actually on dimension foreign well that went pretty terribly I could not get this consistently on size it's all actually a little undersized when I did the other half of it I left it oversized so that I can go back and grind this parallel into size because right now nothing is parallel nothing is to size but I'm going to keep seeing this through to its inevitable failure because I think it will still work the way to think about this is everything up to the last tooth is essentially roughing and that last tooth is going to set the final shape and I actually need to make this in two pieces anyway so that it will fit in my Arbor press so what I'm going to do now is go and actually grind this part so it's at least parallel for now and still leave it a little oversized got this section fairly well trued up it's still oversized again going to grind afterwards because in retrospect I do like doing it that way did the math here I'm going between two and three thousandths on each tooth tooth spacing works out uh sixty thousands between teeth you don't have a Dro but I do have this kind of comically large and yet awesome four inch travel indicator I'll have to move it a couple times tooth spacing doesn't have to be real precise but this will help me keep track of it a little easier of course there's one more tooth I need to do back here that I can't get to because of the jaws of the Chuck but we'll figure that out later foreign foreign this and then ground the first three sides of it before I started I measured it and then measured it afterwards so I know how much I need to take off the other three sides to keep it even got about six thousandths to go so somewhere in this process I probably took more off of one side than the other so it's probably not a perfectly regular hex so what I'm looking at is kind of where parts that are turned is breaking on there to decide if I need to take more off of one side or another to even it out if everything is even that circle is perfectly circumscribed around that hex it's right where it should be I made three of these blanks two out of aluminum to kind of get my numbers dialed in and then test them and then the real one will be made out of 304 stainless 303 stainless would be easier to machine but I had a piece of 304 and nah I'm a glutton for punishment foreign one of the mistakes I made on this is these flutes really get packed out I should have made those deeper so there's room for the chips especially going through something that long so I kind of need to back it out occasionally and clear that out I don't want to drag these back in well I got this one to the point where it won't go forward it won't go backward foreign I guess all that's left to do now is try the real one got a whole bunch of anchor Lube on there see how this goes foreign well that was a struggle but the result's what really matters and those came out pretty good because this piece was a little undersized when I hit the first tooth on this one it was really hard to push that through once I got that broken through it went pretty well asking a lot of that little Arbor press probably a little too much but got it done foreign of course I need some way to hold these things now so I'm just knocking up a little hex mandrel since I struggled with the collet blocks before I figured I'd try and do it in the spindexer this time thank you so this is where this gets a little wonky this shaft measures at 986 so that's either 63 64 or 25 millimeters it's pretty much right on either with 15 splines it doesn't work out to be a standard pitch or module in either metric or SAE so I don't know what that spline is actually supposed to be to complicate things even more you basically have three different ways that splines will fit together you'll either have them bearing on the outside diameter the inside diameter which is not very common or kind of on the sides and so kind of looking at the wear on this and where there's rust it looks like this is probably a side fit it's kind of fitting right along there on each one honestly for the way I'm doing this I don't really need to know what the standard of this is because I'm just making a piece that fits this so just looking through the formulas in here if I look at internal splines my minor diameter for a sliding fit you want it one and a half thousands over with the tolerance of about two thousandths so we'll just leave a little extra space of course being 15 splines when you measure between two you're not measuring straight across so I'm gonna have to figure out some math here I'm sure there's a good way to do this mathematically but I just drew up in CAD a 15-sided polygon scaled it for the measurements I took checked some of the other points that I also measured came up with 8 10 and change with our clearance let's go 8 12. and the last thing I need to do is cut a little Groove so the shaper tool has somewhere to run out now I just need to grind a tool bit to match the profile of the teeth of the spline but I don't think it's really going to be practical to try to grind it to match this we'll just get a little mold release on here I need something that's the negative of that basically what I want to cut out involute splines come in 30 degree 37 and a half and 45 degrees and I'm trying to just kind of eyeball what this is because if I can just grind a trapezoidal tool to that angle it's a pretty good starting point to get it dialed in it looks like it's 37 and a half yeah it might be 45. so what I just said there was actually completely wrong because it's actually the pressure angle not the included angle that's 45 degrees I spent a long time trying to work out the geometry of what the spline should be with some online spline generators didn't really get anywhere with that other than figuring out it's probably a 30 degree spline because that's the most common one but none of that really matters because all we're doing is fitting this to that so grinding this to 45 degree included angle I actually got it pretty darn close and so what I'm doing here is using my phone with just an Overexposed picture of a piece of paper as sort of a light box and the little magnifier and I think it's close enough that I can actually just finish it with the stone well that is not perfect but it's probably about as good as I can do and I think it's going to be good enough foreign foreign so I shortened up the stroke on the shaper moved the ram all the way back and now at the end of The Stroke it's ending right there which is not going to work so I'm going to try to shift the spindex I'd rather have it in a little bit more but that'll work give me a little bit of room to cheat this in or cheat the tool forward so now I've got the spindexer centered up at least on the side to side on the tool it doesn't eat up and down really I'm going to set my stroke so that the tool holder won't hit the end of the hex Arbor [Music] foreign foreign looks the part it's not even close to fitting though well I got that to the point where it is a close fit I would say so for this I just kind of kept cutting a little by little until I got it to fit I'd like it a little easier to get on there I think I'm going to go ahead and do the second test piece and just go a thousandth deeper foreign here because this first tooth is a lot deeper than the last tooth and just kind of get progressively shallower as they go and this tool is sticking out the top a lot farther than it was when I started so that just shifted up as I was going so while I had the number on the dial carefully dialed in doesn't really mean anything now so basically need to touch off in the bottom of that first tooth that I cut that's going to be really hard to do so what I've got is I've got the indicator on The Clapper box here I'm going to come down and when that tool hits the bottom it's going to start moving The Clapper box up I should be able to see it on the indicator I'm going to back off a couple thousandths which conveniently puts that right on zero then I'll cut it test fit repeat test fit number three close test fit number four number five super close round six seven I think that would tap on there two thousandths at a time round eight that is the fit that I want I think that's enough practice rounds it's game time [Music] [Music] that was kind of a tough thing to get the camera in a position where I could still see what I was doing so I didn't video a whole lot of it foreign passes of one thousandths each I call that a really good close fit might want it a little looser but I think I'm going to leave it there it turns out this needs to sit back down in that inner recess a little bit and it's just a little too big I do need to swap that out for a stainless set screw foreign just barely see it down in there it's all together there also needs to be a shaft collar on the other end here so just knocked one of those up same procedures as before and now you can watch the back of my hands as I put this in there well that was a challenging project but I'm really impressed with how that came out my only real regret on this one is no one's ever going to see that but at least I've got this one that I can set on a shelf and look at from time to time I hope you enjoyed that and if you want to see more like that stick around and maybe consider supporting me on patreon

Channel: Jeremy Makes Things

Views: 885,711

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Id: y3L1SyEd7EY

Length: 28min 28sec (1708 seconds)

Published: Fri Nov 18 2022