CENTERLESS GRINDING ON THE SURFACE GRINDER

hello everyone welcome to my shop I'm Robin today we're going to do some machinist problem solving I have two different pins here that I've made before and usually only dim in quantities of maybe 12 of each so these were turned and then he treated and then left plus or minus 1/10 tolerance nothing crazy but I'm doing a hundred and fifty of each now and all of a sudden lapping 300 parts sometimes they might have as much as 8/10 on them is just totally impractical so this little adventure is going to be on how I figured out how to soundless grind these on my surface grinder quickly without a monumental fixture so let's dive in so here are my problem parts this is 0.3 28 diameter 2164 diameter a to drill rod it's got a hole tapped in it and the ends are have a bevel on them and a smooth blend and this has to be lapped to 0.3 28 it grows some from heat-treat so these can have anywhere or maybe 4/10 2 depending on the stock might have 8 tenths on them to lap off so this is obviously done this is ground and that was my problem part had 155 pieces to do with that this is the other part this is 23 1 to 5 diameter and this was turned with leading 5 10 so in here for lapping and after he treat and but I wasn't this part I wasn't really considering because at first I didn't think I could do what I'm going to describe here so I thought about this and since the grind width of these is a little less than half an inch I could actually grind this with a full face of the wheel with no traversing these this particular part could be through fed Center was ground if I had service grinder but I don't so let's talk about centerless grinding just a little bit for those who have no clue about centerless grinding sarah's grinding is a method of having a regulating wheel which is typically something it's a rubber bond hard rubber bond think of a crate X or bright boy stick if you've ever seen one of those think of a wheel like that that's been dressed true so it's got a grip it's got a little bit of very minor amount of cushion to it but it's got a grippy surface that will tend to hold the part you have a rest blade rest blade typically has roughly a 30 degree angle on it such that the part can sit in here and then you have your grinding wheel opposite okay over here and the part sits on the there between those two rests on the on there the blade the regulating wheel rotates this way therefore the part goes like this with the grinding wheel not against it and the grinding wheel goes like this now what the regulating wheel does is it just keeps the part from spinning with the wheel so it's got more traction here because of the angle uhm tends to give a vector where this gives a little more bite into this and on the grinding wheel therefore hopefully you have a situation where this turns slowly regulating wheel turns and real slow and the part turns relatively slow and then the grinding wheel obviously goes it's normal surface footage so in through feed situations this you actually have a situation where these will run through axially through the blade here and you'll dress with the grinding wheel being progressively smaller towards the end to the finish size and you can actually run apart through one time buzz off the stock and you're down to size now the thing that's real important about service grinding is this relationship here from Center Heights up here down to the wheel Center life I don't have that drawn very well but basically you have to have this situation here where this is above Center and there are angles here that are the optimum angle for a rounding action of this if you have that real too far off the parts will be of all kinds of shapes they'll really be bad they won't round up and if they were around they can go out of rounded badly when you grind them so this is regulating wheel type well I don't have a regulating wheel there's another type of sandwich grinding which is called shoe centerless grinding and shoe centerless is typically where you have an actual shoe that rides like this this is shoe here shoe here in a round part let's say it's a outer race of a ball bearing and you're going to grind the actual ball track in here with my D grinder the Odie's already been stylus ground the faces have already been ground and you'll come in here with an ID grind wheel like this and grind this well what what makes it turn a magnetic plate behind it like a magnetic similar to magnetic Chuck whose axis is just a little bit off-center in this direction here so that there's a constant affective it's pulling into there and the part actually just rubs on these two shoes sometimes these are a wiffle tree style of shoe where they've got multiple pads and I've been a distributing system to make them even but does the whole science in itself here but shoe centerless is what I said okay I can make something like that for my grinder and what I'm going to do use for driving is since this has a tapped hole in it I said okay I can put a screw in there like this and then drive it with a ball end a text tool that because this allows me to have this kind of action without having any influence but in order for it be totally free I have to add another flex here such that I'm not putting lateral loads when I do this but the drill okay even though there's some loading it's very gentle I'm not going to pull the part out so this gives me my driving force and with this I'm actually going to sense the returns clockwise I'm actually going to go against the grinding wheel because I have the torque to do it so that's that so then I need something that has this 30-degree relationship so here's my block that I've made and this is just a piece of a - I took a dovetail cutter and actually cut into this and this actually used to be flat here what you see here is used to be on top all the way across and that's because I mistakenly not thinking through completely was thinking this is the 30 degrees this is the back but that's because I was picturing the grinding wheel situation like this but my grinding wheel situation is actually like this okay in the surface grinder where the wheels above relative to my shoe so after I put it in straight and realized wow I'm getting some really ugly shaped parts I realized uh you didn't do this right you need your thirty degrees so that's what this is where this is actually super glued on and Chuck when I found my angle here and that gives me the ability to have my grinding wheel behind Center here so instead of directly above its back here and I quickly got to where I could get this part to round up the spring steel here just loads and that actually holds this in place so I just picked a spring steel that holds in place and so now I've got a situation where I can just spin this with the drill it's held tight against this I hardened and ground the two surfaces where this hits and there's only a 64th of an inch difference between the two pins a little endstop on it so that when I'm pushing in here with the drill I don't push it clean off and so you can see that do you see what's going on here now I did these first and I wasn't even sure really how I was going to do the other ones and the other ones I said yeah you know I could probably take a piece of tubing like this and turn down the head of the screws so that it's also a press fitting the tubing and then put these in and that's exactly what I did but these n same drill arrangement and spun them like this so that's what I did and when I ground the flats here I actually put them in the vise the same vice that I used to hold it so I ground this and then I ground this bearing face back here remember this is hardened a2 here I actually just sort of induction hardened these with the TIG torch in the areas where I needed to be hard the rest of it's still soft and that way when I put this in the vise I was really getting good straightness so that's the whole system there we've got the driver and I got some pictures here showing it in action so the purpose here is showing you problem solving using a few details of what you know and coming up with a solution and this really ground unbelievably well it looked clearly took a few seconds to actually grind this the actual grinding part loadings are obviously a little more than that to screwing the things on and off but the actual grind time was just buzzed down like I mean it came in and I'll show you in the video where I come in with the indicator and I'm more actually watching this at the millions best test indicator for my zero position and checking where they are so just thought this would be a neat idea guys might is very limited use here because of the size of this but the principle and the idea of doing Xu centerless on the surface grinder it's just an interesting thing I thought you guys might get a kick out of seeing this picking up the threaded parts using the drill driver that's rated my drive screw get ready to load that into the fixture slide it in under the spring drive underneath I have a stop on the grinder for the axial position I have a rubber band stuck on it tight to the stop put the driver in spin it up feed down you see the sparks there we're only taking a little bit off get out from underneath blow it off slide it out finish it is really nice really happy with that here's a close-up version blown out the seat making sure not to go on any grit sliding in the part up against the stop actual stop letting it slide down in against the stop and here you're watching Decatur you'll see me feed down to zero and then back off again and you see the spark corresponding sparks sparks out get off and then caters up one knee up on the column where I can see it slide the part out and then check with the indicating Mike's here one division is one tenth on this nice and straight nice and round even though we can't check nap around is here I did check around this other way be block and it's good remove this screw and get ready to do the next one Barnard up the other ones I just dig by using the tube plastic tube and so right back hope you found that interesting I didn't have much time to take a bunch of detail about construction how I did things on this I'm not changing my style I just didn't have time to do much more than I showed as far as how they were built I just had to get the job out the door thanks to all the new subscribers appreciate it very much if you enjoy this kind of content please subscribe share tell your friends and I'll be back

Channel: ROBRENZ

Views: 91,824

Rating: 4.9758573 out of 5

Keywords: centerless, centerless grinding, shoe centerless, surface grinding, grinding

Id: ZXAVst_0Xxk

Length: 12min 38sec (758 seconds)

Published: Thu Feb 02 2017