Grind a face trepanning tool for the lathe

[Music] what the heck is a trepanning tool and why do we even care welcome back Doc's tools I'm Tom so today we're going to take a look at a hand ground trepanning tool and this is an example right here we're gonna learn how to grind it and we're going to learn how to use it in the lathe and why it's a really handy tool to know about let's check it out okay so here's the job and what we're trying to do here is my friend Paul Compton in over in the UK he's got some relatively expensive material and what he has to do is he has to produce some rings from it some ring shaped parts but he also has to preserve the core so that he can make another part out of and there's a way to do that and it works out pretty good and that's a trepanning tool and so instead of buying you know twice as much material as you need you can get everything you need out of out of a single chunk okay and this is the trepanning tool and the idea is we can come in along the side of the material here like so and cut a face groove in it or trap an a an annular ring out here and then we can separate the ring and still preserve this this core material to make the the other part so what he's doing is I guess it's he's making valve seat and valve guides out of a particular bronze alloy that he's using anyway so we're going to check out how to grind one of these tools here and actually try it out and see how it works [Music] all right so here's here's the one I showed what we got to do is what I like to do just to kind of get me going in the right direction as I just kind of sketch on the on the tool blank what I want to do here and so this will be straight here and then we'll come back like that and then this will be relieved at and then this depth here is equal to your the width of the ring that you want to get out right so you know you can actually go pretty far and the ratio here I guess kind of guidance on the on the ratio is maybe six or eight times the the width here so if you take this with let's say it's you know an eighth of an inch or something like that you can you know you can probably go up to maybe an inch and you know that's pushing it that's eight times the width so six or eight times it's probably a practical limit a reasonably conservative practical limit for a hand-ground tool so now this actually takes a while to carve off all that material on a bench grinder so we're going to use is we're going to use a cutting disk and we're going to come in here and just nip out these nip out this big block here and then slice that off and that'll give us a good head start on on our tool okay so let's go do that so that saves a bucketload of work there all right so the cutting discs really has a potential to save you a bunch of time on the on the bench grinder now this is a m2 cobalt so yeah grinds it takes a little while to grinded so anyway that's an easy technique for for getting some out of your way so let's do a little a little grind in here [Music] Oh [Music] ah [Music] okay so we're sneaking up on it here we're looking pretty good now we got to start really concentrating on the the relief angles here in particular on the inside edge so if we look at the what we have to do here okay the outside edge as you can see there actually you know what let's just look at the ring here that's probably the easiest this this inside edge or outside edge I should say has to have significant relief to clear that curvature to clear this curvature here so we're really going to focus on on this inside edge the outside edge kind of takes care of itself because when you're on a when you're on an edge like this the material is curving away from it so it kind of gives you kind of automatic relief so you don't have to to focus so much on that and I get the shakes here huh none of coffee or too much coffee anyway so this inside edge here is really really the one that we have to focus on when the tools on Center this lower edge it has to curve away and clear the material on loops underneath and you can kind of see it on this one this one that's already come on and drop and stuff all over the place okay so we just have to clear that that material there maybe we can see it better like this oh yeah this is a better way to show it okay so we're coming in this way like this and you can see on the inside you know we have to have clearance there okay yes come on mr. Bose oh that's a better way to show that so here's our new tool and actually doesn't look too bad it actually doesn't look too bad for this for this particular radius so well sometimes hey you know what sometimes the blind monkey finds a nut once in a while so our blind squirrel finds a nut okay so we refined it more now let's take a look at it here so this is the direction of cut this way here and you can see you see that inner edge we're looking at the inner edge here if we put it on center we need clearance for that curvature and that's really the whole secret to a trepanning tool is getting the clearances correct they they work wonderfully but sometimes understanding the clearances can be a little bit tricky and as this radius changes as we get in closer to the center it curves more sharply right so the relief has to change so as long as we're you know this tool will work for this size and larger and maybe a tiny bit smaller okay but so if we needed to cut in this area of the solid the relief would be significantly different so that's kind of the challenge in these tools is understanding the relief so actually this looks pretty good here I'm reasonably happy with that now to change the width of the tool once I get the inner relief the way I want I would focus on this outer edge too to change the width of this and to get it if I have a specific width that I was looking for I'm not looking for a specific width here I don't know what Paul's doing so we'll probably just use this tool as is so I'm going to go grind a little chipbreaker in it to help us out and then we'll give it a go now something else to note here too is hopefully you can see this is the the tool is tapering from the from the front to the back so this is the top relief I call it it may be side relief I don't know the terminology is a little confusing but the width of the tool its widest in front and then behind that edge it tapers back so we have kind of a dovetail shape there so to speak okay so as a narrower here than it is there and because we're cutting in this in this direction all right so go grind a chipbreaker on that and then we'll set it up in the lathe and cross our fingers that's actually pretty good there you know what I'm not going to get greedy I'm just going to you know what I like the looks of that yeah I'm tempted because I was lucky and got a nice lineman right out of the gate attempted to put a little more on there but you know what it's going to work fine okay so we get the tool in the holder here now we just got to get it set up correctly here I got it loose I can wiggle it around and what I want to do is just kind of run it up and and look at it and look at the clearance and what I'm doing is I'm just feeding it in hard to see here and I'm looking at the at the clearance to make sure I still have clearance and that looks pretty good right there a little more and then I'll lock it down and check the center height and we'll give it a go and see if it's it it behaves itself okay all right so we're going to just sidle up along the side of that little little guy there actually and then just plunge into that face and see what happens all right let's give this thing a go so I'm going to come up and I'm going to just touch on the that center portion there and we're looking pretty good there and I'm just going to zero the Dro so I have a reference point then I'm going to just do a little test plunge in the face there see how she behaved and so far so good [Music] and I'm just looking at the tool the size of the tool make sure nothing's dragging on the sides of the tool alright let's see let's get some liquid love going here it's always true panics one of those ones you really want to just keep everything kind of wet [Music] [Music] I'm looking on your knees I think I gotta take a little more off the tool yeah I got a little spot right here that looks like it's going to touch okay so I need to relieve the tool a little bit more all right let's try that again I put a little more relief on the side there so we'll see what we can do here get back into position okay here's our juice going sure block FK looking pretty good alright let's go to town here [Music] [Music] you okay so there's a trepanning tool for making rings and leaving a stump in the middle so anyway try it out granted tool for yourself and see how you like it it's one of the beauties of high speed steel is that you can make anything that you want it's um it's important to understand how to grind your own tools because you can't always get what you need in an inserted tool in the kind of time frame that you might need it so this is something you can do and in I don't know a half an hour or 45 minutes once you kind of get used to it and you're off and running and it works fine you can use this on pretty much any material here so anyway hope you liked the video and throw some comments in the comment section and let me know what you thought of it thanks for watching guys [Music] you [Music]

Channel: oxtoolco

Views: 77,010

Rating: 4.9680319 out of 5

Keywords: Trepanning, Hole cutting, Rotabroach, Holemaking, Hand ground toolbit, High speed steel, Lathe tool, Lathe, Manual lathe, Face groove, Machinist, Toolmaking, Parting in the lathe, Grooving in lathe, Chipbreaker

Id: 6PcEBaset1I

Length: 16min 54sec (1014 seconds)

Published: Mon Jul 03 2017