How to use a D-Bit Grinder - The Basics!

okay let's insert our workpiece here I've got a half-inch call it what why did I think this is half an inch hello internet my name is Quinton and this is bloody axe today I'm gonna show you the very basics of making your own cutting tools with a debate grinder now I am far far from an expert on this machine and there are lots of different ways to use these machines and these machines are all a little different I have twelve different manuals for different versions of AD bit grinder and all of them have different procedures with the same basic controls for making cutters so I'm gonna show you what has worked for me for making the most basic form of dbid and we'll go from there okay let's go what's a D big Rinder it's one of these all right video over a good show everyone I'm just kidding there's a lot more to talk about a debate grinder is kind of a specialized or simplified I should say form of tool and cutter grinder so it's got a spinning grinding wheel here in this case a diamonds Cup wheel you might have an aluminum oxide Cup wheel on there you might also have a cut-off wheel or straight wheels of various types and then there's a very elaborate work head here which has a lot of adjustments for holding a tool relative to the grinding wheel in very precise and repeatable ways now the official highs on death law of the debate grinder is right there in the name it's for grinding D bits what's the D bit well contrary to what many internet commenters would have you believe there is not exactly one name for everything in machining and funny how that name always seems to correspond to the thing that they call the thing but that name D bit refers to different types of things in different types of trades and different types of machining but in this case I'm referring to this form of single flute cutter so this is a piece of carbide that's been split in half and then a shape ground into the end of it here to form a single flute cutter this is the most basic thing the d bit grinder does is if you want to learn how to use a d bit grinder you better learn how to make these guys first and what kind of cut does sky actually make well this is an end mill now it doesn't look like one because it's a single flute cutter not something you're typically used to it doesn't have spiral flutes or multiple cutting edges but it is an end mill and in fact it made these cuts that you see here now where these guys really shine is if you need a very specific nose radius in the bottom of a slot or if you need a very specific angle on a V groove or you know specialty forming and shaping operations like that you can very quickly and easily grind a single flute cutter to do exactly the type of operation that you need but it's actually pretty useful for a lot of other types of grinding operations in the shop you can coax it into regrinding end mills and making lathe tools and making engraver bits and various specialty end mills and just about any single flute cutter you might want to make to start with you're gonna need stock now you can buy dedicated stock for D bit grinding from mcmaster-carr for examples where I got this but you can also just use any old dull or broken cutters that you have lying around anything carbide or high speed steel will work for you so you can just take an old broken center drill or nml or whatever lopped the end off or grind the end into the shape you want and Bob's your uncle now if you do want to start with fresh stock such as I've been using here I recommend buying something like this from McMaster or similar outlets this is a piece of solid carbide and it has split ends and you really want to buy the split stock because otherwise if you buy the solid round stock the first thing you have to do is cut this split and that's a lot of grinding on your expensive diamond wheels let's look at the basic controls and there are a lot of them on a d bit grinder which can be a little bit intimidating but it starts to make a lot of sense once you break it down into sections so there are two pivots and three slides and those give us all of our degrees of freedom and most of those degrees of freedom have a course feed a fine feed and a lock so all those degrees of freedom multiplied by two or three separate levers and well you got a mess of levers start with the most basic and that's this bar right here this bar is like the ways of the machine and there's going to be a lock down here on the head which allows you to free this head up and slide it back and forth so that's your course feed and your course rotation now where it gets interesting is that the bar itself also has feed and tilt so it's a bit like if this was the carriage on your lathe this is your ways except the ways can also move so we do that with all of these controls over here now some of these details vary from debate grinder to D bik rinder but this is a Kuhlman su 2 and they're all going to be fairly similar to this if you've got a deco lure one of the the newer Asian clones they're all going to be relatively similar to this we have two locks here affine adjust here and a micrometer adjust back here this lever right here locks the tilting of the bar so you can see that I moved ahead even though this right here is locked so the head is not rotating on the bar the bar itself is rotating and then this right here is the fine feed for the rotation of the bar so if I turn this guy look at the head over here see how the head is tilting now the way that you actually end up using this guy is as a stop and that will make more sense here in a bit now this guy right here is the lock for the traversal of the bar so in addition to this bar rotating this bar also slides in and out carrying the head with it so once I unlock that now I can move this micrometer that work head is moving now this is a very very fine feed each of these tick marks on here is half a thousandth so this is a high precision way to move this bar and by extension move this head so this is effectively the fine feed for the lateral movement of the workpiece up here on the work head now we've got a main lower joint back there which rotates the head this way and then we've also got this joint here which allows us to swing the head 90 degrees this way these two pivots can do a million different things but for the basic d bit that we're gonna grind it's very simple imagine my cutter that I'm grinding is in the collet it's my finger here and the top of the cutting surface is my fingernail you can see how this main pivot here tilts the cutting surface away from the grinding wheel so that's creating the clearance behind the cutting edge so what you're going to do is going to set it to 25 degrees and you're just gonna leave it there before we go any further we got to talk about basic debit cutter geometry it's a single flute cutter so the split line the halfway point of the cylinder if you like is the cutting edge now that clearance angle that 25 degrees that we just looked at is behind the cutting edge that's this angle back here so we have to be clearanced right behind the cutting edge and that's what actually makes it a cutting edge right and then as this guy spins around this whole area back here has to be a smaller diameter than the cutting edge so the cutting edge is the full radius away from the center line of the cutter but everything else is a smaller radius than that so that as this guy spins the cutting edge is engaging with the material but nothing else is touching and then this right here is the nose radius on the end of our cutter just like any other cutter on the lathe or on the mill nose radius affects a lot of things it affects surface finish and tool pressure and all that and then there's an end clearance angle at the end here so that as this mill is cutting the end of it is not contacting the material the geometry is very similar to a lathe tool it's a single point cutter so this nose radius right here is the business and this is doing the cutting and maybe some of this edge here depending how deep you are and then everything else here is just angles to get that material out of the way so with that geometry in mind we can look at that second joint now which is this rotation and for the basic D bit the purpose of this joint is to create that nose radius again imagine my fingers the cutter that we're going to grind you can see how rotating that guy 90 degrees is going to put a radius right on that front corner there up against the grinding wheel now the reason that you can clamp the head to the bar is that the bar then constrains the motion both laterally and tilting and this tilting motion is your basic grinding motion as you tilt it forward and back you're moving in and out and the grinding is happening on the face of that wheel okay you know just enough to be dangerous so let's do some grinding first you want to prepare the blank and to do that you want to get some die cam on there all the way around the back especially and on the end is helpful too because it's going to be pretty difficult to see what you're doing unless you have some kind of reference so the die cam on there really helps so the other two things that you really want in this procedure are magnification and the light if you're of a certain age those two things are invaluable on a dybbuk reinder because things are happening at a very small scale here and it can be really difficult to see what you're doing if you don't have magnification light and die cam okay we're ready to insert our workpiece here this is a quarter inch blank so I've got a quarter inch collet here and I'm going to wipe out my taper with a lint-free wipe here this is a grinder so everything is constantly covered in grinding dust you want to make sure that's not interfering just like any other collet system there's a key and then we've got a draw tube that we can screw into the back and then we slide our workpiece in here and snug that guy down at this point we need to understand this little guy so there's this spring-loaded knob here which has three positions there's a short slot a deep slot and then you can put it between slots when it's between slots the work head is free spinning so you can do circular grinding with that if it's in the deep slot then it's locked so that's the setting it was in so I could tighten the collet and then if you put it in this short slot then it will be locked to a specific range of rotation and different debate grinders very in this regard the Kuhlman has two options for this there's a ninety degree range and a 180 degree range some grinders only offer the 180 degree range but generally for basic debate grinding the 180 degree range is the only one that you're going to need the next thing to set up is the range of grinding motion remember I said this is your basic motion but you can see how it'll go in much too far and it'll go past the split line there that we have ground and it'll hit the call that it will hit the work etc so we need to be able to set the limit so that this stops on each stroke exactly we want that's where this knob comes in here but it can feel like that knob isn't really doing anything because it's nothing is stopping me and you can turn this knob and nothing seems to happen and so this setup can be a little confusing at first the trick is that you need to rotate the bar up against the stop first so this is sort of the course adjustment for rotation if you like so what I find helpful is to unlock the head and then just grab the bar and twist it until you hear it and feel it hit that stop and now you can lock the head and now when you're all the way in now the end stop is having an effect then bring the work head over close to the wheel and then you can set this stop right where you want it you can see that it hits my stop right there and I'm using most of the split area here but not all of it you don't have to use the entire split area for your cutting edge if you're starting with an unsplit blank or maybe you've locked the end off an old end mill or something first step is you need to split it so we've set up everything you need to do to do that it doesn't matter how the head is rotated or anything because it's still gonna be round so you set it up like this and you're all set up to grind your way to a flat spot so how do you actually feed in for grinding well that's what this guy right here is the micrometer so the work head is locked to the bar so this motion here is rotating the bar not the head and now when I rotate the micrometer I'm cranking it very slowly towards the wheel so you'll swipe in do a pass move in tabatha do a pass half a cow do a pass so this is your motion for splitting that blank and then check it with a micrometer periodically until you're exactly half because remember that surface that split surface is the cutting edge and that needs to be on center so that when that thing is spinning the cutting edge is on center just like on a lathe okay we're ready adding some geometry to this cutter now the debate grinder makes some assumptions about the relative position of the flat surface of the cutting edge and all of its geometry is configured assuming that the flat surface is in a particular orientation on this workhead so it has some special tools to allow us to set that up the first is the dot so most d bit grinders will have a little dot that appears it's usually red it appears in this little window back here and that red dot is a magic orientation on the workhead alternatively there might be a dot somewhere on the ring here in this case there's a dot right here it's a few degrees off of 90 and this on this particular debug reinder is the magic dot that dot i showed you in the window means something different on the Kulemin su2 of this vintage so if this varies again by d pick Rinder most of them it'll be a red dot in the window in this case it's a red dot on the ring but the point is to set up your cutter you got to put the dot in the magic place so either the dot in the window or the dot on the line here the second tool is this little alignment blade here this little blade works together with the magic dot to get the flat of your tool aligned so what you're going to do is you're going to put the dot in the window or in my case the dot on the line and they're going to lock that work head in that position then you're going to loosen the collet and then you're going to take the stock and you're going to rotate it around you're gonna line it up with this little blade like so so when this little blade here is sitting flat on your workpiece and you can slide it back into the collet however you need to so you got not too much stick out there and then tighten your call it back down this blank is now aligned correctly for where the machine is assuming it is for creating the rest of the geometry so with the tool bit set up on the magic dot now we can switch over to the indexing position once again there's our hundred and eighty degree motion notice that my cutting edge is not flat it's not perpendicular to the to the grinding wheel this is our clearance angle behind the cutting edge that's what that first big joint that we set did it tilted the entire work head over so that when our cutting edge is where the machine thinks is straight up it's actually leaned over 25 degrees and now you can imagine as we grind this guy around through the hundred and eighty degree range it's going to be grinding away the backside of the tool while leaving our cutting face on dimension and our cutting edge untouched now we've gone a long ways here without ever actually turning the machine on and that's how these machines are you spend 20 minutes setting up a new bit grinder and then the grinding is done in about eight seconds there's two more things we got to do and that's set these two slides the work head has a slide here and a slide here the top slide is easy you want to loosen your course feed and/or lock as depending on your machine and then you're just gonna slide this guy all the way back and lock it in and then there's a little vernier scale here this guy is also going to have a lock on it somewhere and then there's gonna be a knob somewhere over here in this case and you can see that I can slide the head left and right and precise them out with this scale but what is this slide actually doing well picture if the tool bit is rotating exactly around the center of the cutting edge then it's going to make a radius that is the same radius as the cutting edge you're gonna end up with a ball nose and mill effectively so by sliding this further to the right what we're doing is we're making that radius smaller and smaller and for that reason the scale here actually reads in Reverse as we'll see here the math for setting that offset is really simple you just take the radius of your blank your cutter and you subtract your corner radius that you want I'm gonna put a 40,000 or a Dias on this tool so we take 125 tool radius minus 40 thousand sets Kail to 85 now you make it this you have to set your nose radius offset for you do any grinding except splitting the blank you can do that first if you want but don't do anything else to your cutter until you set this scale if you don't do this first all of the geometry of the motion of this head gets all messed up and nothing you do after this will work right in my case the large ticks up here are 50,000 the small ticks are 5 now deep it grinders vernier is tricky because it's upside down and reads right-to-left which makes a lot more sense from the operator position so here's what I'm seeing on the final setting that I used so you can see that I'm past the first major tick so I'm at 50 plus and then the 0 1 2 3 4 5 6 7 'the tick is the best lined up one on the fine-scale which is the extra 35 now and don't forget to lock that slide so it doesn't move while we're grinding and in my case that's this little handle here so snug that up now if you don't have dust collection you probably want to set some up but if not at least do this very very far away from all of your machine tools in this case we're grinding carbide with diamond and diamond dust is machine tool cancer you don't want it anywhere near your machine tools so yeah definitely do this far away from anything that you care about and I also recommend wearing at least a dust mask because you really really don't want abrasive dust in your lungs it's going to sit there for the rest of your life doing damage the first operation is just to move in slowly with the head rotated all the way to the left until you start grinding away that die cam that we put on there and you want to leave yourself just a little sliver of die cam on that cutting edge and then without moving anything just go back in and rotate it through the hundred and eighty degree arc and it'll clearance the backside of that tool here's what it should look like at this stage you can see I've got a little bit of die cam left on the cutting edge and then a relief angle behind the cutting edge and then the backside of the tool is all clearanced if you accidentally go too far and remove all of that die cam it may not be the end of the world but it does mean that your cutter is going to be a little bit undersized we leave that die cam on there just to make sure that we don't accidentally go too far and the cutting edge remains at the full diameter of the blank now we need to do the end clearance so for that we're gonna loosen this joint here we're gonna swing this guy through 90 degrees we're gonna lock it again now if we tried to grind it in this position you can see we're too close to the wheel because of the angle that were tilted downwards for our clearance on the end of the tool bit here there's too much meat now interfering with the wheel so now you want to 0 this micrometer ring if you have a zeroing on there I don't so in the in my case I just make a note of that reading and then I'm gonna wind this back and then I'm going to feed back into that number again with the same grinding feed motion and again until we have just a little sliver of blue showing on the end of that part and now under the macro lens here you can see how those two clearance angles meet at the corner but we've left the entire cutting surface intact now here's where the magic happens so we're back to where we started on our micrometer and you can see we're right on the end clearance there if we loosen this guy now and go back to the straight on position we should also be right on our cutting edge and now watch what's gonna happen I can loosen that joint now we can swing this guy around and it's gonna make our nose radius and because we've clearanced down here on the end and we've clearanced over here on the side all the wheel is going to be grinding is just the top there and then a little bit of a radius on that corner there where the end relief and the side relief meet we're just going to make that radius right there so for this operation you want to lock it again because all we're going to be doing is swinging okay so now here's our four teeth out and there is our 40,000 see that our offset of 85 on that vernier scale gave us the nose radius of 40 thou that we wanted the last angle we need to make is this angle right here so we clearance to the end on the back but now we need to clearance it in this direction so we need like I don't know a 10 degree angle something like that this isn't super critical just enough so that this again isn't going to rub this operation is probably where all of the various debate grinder manuals and users differ the most frankly you can just freehand that little angle on the wheel but I'll show you a way to do it precisely in case you want to so we're going to square this guy up again back to zero then we're going to go over to this joint here that swings the nose radius normally and we're going to set it to 10 degrees in that direction now when we come up against the wheel you can see that we're 10 degrees off this way but this right here is our nose radius so we're 10 degrees the wrong way now some debate grinders will let you rotate this portion of the head past 90 by a few degrees for exactly this purpose this particular grinder does not however the reason that we squared up that main clearance joint is so that we can do this flip that guy around 180 degrees lock it in that position now we're grinding it upside down but now the nose radius that does the cutting is back here and so now our angle is falling away from the nose radius just like we want and here's our final a lovely little single flute endmill I hope you can see all the different angles and clearances and radii that we put in there and how they all interrelate so let's make some chips with this guy speeds and feeds with these guys are pretty simple you just run them balls out rpm pretty much sighs you can go and maybe feed them a little slower than you would with something like a for flute cuz you've got you know one quarter as many edges and you got to go a little easy on the depth of cut these are gonna start to complain somewhere around 10,000 steel and maybe 15 or 20 in aluminum depending on the diameter of the cutter now here's where the D bit really shines if you will and that's the surface finish this upper area here you can see was done with a conventional cutter and you can see that the reflection of the numbers in this on the scale is sort of visible but not really and then down on the D bit cut you can see how it's just like a mirror those numbers come through perfectly and then here on the macro shot you can see our nice precise corner radius there you know this cut isn't very deep so the radius is not super easy to see there but I hope this at least gives you a taste of what's possible with debits and we've just scratched the surface on this amazing machine but thank you very much for watching and we'll see you next time you

Channel: Blondihacks

Views: 108,579

Keywords: blondihacks, machining, machinist, abom79, this old tony, vintage machinery, steam, electronics, making, maker, hacking, hacker, lathe, mill, woodworking, workshop, shop, model engineering, engineer, engineering, live steam, machine shop, metal lathe, vertical mill, metalworking, metal shop, jewlery making, diy, home improvement, resin casting, how to, do it yourself, do it yourself (hobby), ASMR, mini mill, mini lathe, tutorial

Id: VLRg24LrcJw

Length: 25min 34sec (1534 seconds)

Published: Sat May 30 2020