Indexable parting blade and dbit grinding

[Music] hey welcome back a little project today this is a multi-fix a grooving tool holder this is basically an ancient style of grooving holder which takes a high-speed steel blade with a trapeze trapezoidal cross-section as you can see this dovetail slot and that gets clamped here and it's a fairly narrow high high speed steel blade like like about 10 millimeter wide and they work they work for grooving but for grooving i have better systems i have needed the insert a carbide tooling eye and i can cut grind custom tools but this one is basically useless for me and i i think i don't even have a parting blade for this or a grooving blade so what i did i went on the internet i ordered a very narrow inserted parting tool this is a 1.7 millimeter wide parting blade with a 2.2 millimeter insert carbide insert they come in different flavors this is a steel insert but there are also inserts like this one with ground and polished edges and surfaces which are for plastics and aluminium and these inserts sit in sit in a double v arrangement v on bottom and on top and they are slightly tapered so they wedge themselves in until they hit the back stop usually you give them a little bit of a whack with a soft faced hammer until they go in all the way and to get them out you have this the syringe with with this cross section here which goes in here and you just pop it out so there's the insert it goes in like this then you give it a whack and drive it in this obviously doesn't fit so some modifications will be needed to do this yes i'm fully aware that you can buy an ax a multi-fix for parting blades and there is also at least one import reseller who sells point blade holders but i don't buy these holders from importers or resellers so if you want to write that comment sorry i'm not interested um and i have this one already so i'm going to modify this these are usually at least case hardened let's find a file find a new file crappy needle file yeah this is uh this is nice scent and crisp we have a clamping arrangement down here but we'll see if this is good enough for uh inserted parting blade otherwise we have to modify the clamping too to have a clamping from above down but i have an idea for that too if if this clamping from down below doesn't work so we have this clamping shoe cut out there is a spring in here keep it under tension when you loosen the screw and a high strength screw to pull all this mess together i already scratched the line on center height i just put the tool holder into the lathe and i put a piece of carbide ground to a point in the spindle just scratch the line this is center height of the spindle so when i put this tool in here i need the carbide insert to be at this height or below so i can adjust it up because when i scratch this line i put the tool holder in all the way down the lowest it goes that's also the reason why i'm going for a 19 millimeter blade these are sold as 19 millimeter even in reality they are a little bit less these plates also have have a double double rearrangement so this is the arrangement the this blade has if you look onto the front and this angle here is so this is the parting blade i bought uh huffman group is the sharp this is the article number parting blade steel body 19 millimeter height 2.2 parting width cad file cutting data and here's a sketch of the cross section the height and the the angle is 150 degree between those two uh angled surfaces so this is not correct here from here to here it's 150 degree like this that means so a full full angle would be 180 180 minus 150 is 30. so this is 15 degree from here to here so and the idea is that we we have a little bit of an under cut in here with these 15 degrees so the blade gets pulled tight up against the face and cannot slip out when i said that this is going to be a simple project i wasn't lying uh we just need to mill the slot wider and grind a d bit and i think the d bit is the only real reason why i'm making this video otherwise it would be just milling a slot that would be making a video for drilling a hole but as this is a simpler project we can go into a little bit details here and a set of parallels get this in here now this is so this is able to tip a little bit because the back side here has no flat surface due to the shape of the multifix we're taking only one parallel and grab this holder way deeper in the wise like this so it aligns vertically on the fixed jaw so it doesn't sit like this or this when it's up that high it doesn't align as well on the on the fixed jaw when you drop it down it does so one parallel drop it up against and we give a little bit of drag on the on the y so we can still kind of move it but it's in place and for this orientation side to side we'll dial that in get a little bit of preload this is two micron indicator so this is fairly uh this is a bumpy bumpy roller coaster so we start here at zero and it climbs it comes fairly significant it even over travels the indicator so what we're going to do is we'll get a little bit of a pry bar below the part a small brass pry bar here and i will move the table slowly and you can see it drops off and i will just use the pry bar down here to erase the part a little bit that's like a three-hand a fair or at zero okay that's already better so we start like 100 back here and now we take our pry bar and we lift it a little bit it doesn't need to be like 2 micron end to end but it would be nice if it was within 10 micron raise a little bit yeah that's that's okay i like that now let's tighten the white stone it will move a little bit okay let's start here at 80 okay that's darn good i like that drops a little bit but with that surface finish hard to tell and if it is really like 10 micron over this distance that's really not a big deal by the way for those who have never seen it i don't use a magnet indicator holder on my mill very much i have this is part of my solid indicator stand that i built that i have a video on and i just mounted a post the six millimeter post solidly to the head of my mill and i can put this indicator holder on there and that's way nicer than having a magnet base magnet bases tend to scratch the surface you mount them on they can start to tip over time if if they get dinged up or if there is a single chip under it this doesn't tip there is no way to when you tighten the screw it's it's it's locked okay that's the end mill i'm going to use or at least try to use uh this is a six fluid carbide end mill with a coating for hard milling and another geometry for her milling [Music] the the flutes are not very deep the core of this end mill is very thick so this is a reasonably stiff tool so i'm using a five millimeter dowel pin to touch off the height so i drop the cutter so the pin doesn't go under under the cutter now i'm slowly raising the quill until the pin goes through there there it is okay now i hit just the diameter of the pin in this case five millimeters into the dro when i crank the coil down to zero i should be reasonably precise at full depth but i will stay like 2.2 millimeters off the floor right now now i just want to widen the slot okay this is this is cutting quite well uh this is definitely hard but not stupid hard and that's probably only case hard but we'll see once i go in deeper uh you notice that i climb cut this is preferable uh climb cutting is always preferable but it's not like a manual machine like this it's not always possible but i'm only stepping in point five millimeters or one millimeter in next pass and that's not hurting anything on a climb cut okay that's a one millimeter wide cut at 3000 rpm now as we milled out the slot we need a cutter to create this 15 degree undercut and the easiest choice is a d bit a single flute cutter something like this this is a large 90 degree almost like a countersink i think i used this too to mill a large chamfer take a piece of carbide or high speed steel if you feel a bit feel a bit vintage split it in half exactly to half the diameter you grind your shape uh cylindrical grind it basically and then you grind something like 15 or 20 degrees of back clearance behind the cutting edge that's this facet here then you roll off the remaining material from from the end of this clearance so the clearance drops off until here then it's just cylindrical clearance or in this case tapered because it's on an angle so that's what we're going to make just with different dimensions already found a piece of carbide a carbide drill with six millimeter shank good quality and we're basically if i can find bloody pen um i'm going to make a cutter that looks like that's the shank like this a very weird dovetail cutter with a 15 degree here so that's basically this view now when we flip it over 90 degree we get like this that's a cutoff line up here a shank and the split and here's the undercut and this split is exactly on center line uh the release of course not drawn here but that's where we're going to grind on the d bit grinder so hold on to your heads okay we're at the d-bit grinder and i'm setting up to split the carbide in half and if we do this right we can make it a little bit easier on ourself thing the dividing head here is three positions indexing every i think 15 every 15 degrees and you can set it 280 degrees this locks the motion to 180 and you need that this to roll the back relief and you can set it to spin freely altogether if the handle doesn't get in the way can free spin so the way we start grinding we can make it easier ourselves let me demonstrate to you with this piece of blue tape go to this is now our 180 degree motion this is what's used to to to grind the back relief and when we're at the left extreme left position we want the flat of the split we grind to be horizontal so the back release starts there so we basically want the split to be like this and then we roll off on the back that means that we go to this position to grind the flat to split the carbide blank in half then we set then we move over 90 degrees and lock our rotation to 180 degrees this is really hard to explain then we can in the same setup roll our back relief or back clip every other joint here is set to zero everything is locked and we're good to go we rough position this fellow here i'm using a diamond wheel d125 is the grit there are converse conversion charts for mesh size or whatever other grid designation you use but here in europe the d for diamond and b for a cbn wheel is the common grid the smaller the number the finer the grid it's fairly easy so safety losses then we get our our dust chute below because this operations creates quite a bit of of uh combat dust about half the diameter of the of the carbide blank and now we just traverse in and swivel the tool back i'm going to grind about i don't need very much i'm going to grind like this maybe split about six millimeters off the blank in half one little trick um you cannot adjust this um the graduated ring on here the dial you cannot set this to zero but what you can do is you can crank it to zero and then use this upper dial to move the whole spindle assembly and this moves the spindle back and forth and you can use that to zero to touch the grinding wheel against your carbide [Music] [Music] so [Music] okay here is our carburette blank split in half yeah we were like like 30 microns over but shouldn't be an issue in this case i'm not going to fool around with this forever now we need to grind the 15 degree back taper which is our dovetail shape for that we on on the chinese stupid grinders at least on most of them down here is a pin and once you loosen the lock on this side you can swivel this guy and you can move up to this pin and this is your hard stop for 90 degree it's also adjustable it's eccentric and there is a set screw when you loosen this you can set this to to your desired zero um so we we can go 15 degree but that's the wrong 15 degree we need to go the other direction and for that we can take this pin and pull it out and then we can basically move wherever we want like this the only problem in my case is um i don't have the the graduation stop at zero so we can loosen this style here move it to 90 over here and now we can take our 50 degree back taper and lock it down here we set the the back relief for the for the od that's important so the cutter doesn't drop 15 to 20 degrees 40 bit is a good choice i'm going for 20 degrees today because well i feel like 20 is good then we move this whole the whole work head closer to the grinding wheel once again like this we make sure that we have a lot of travel not a lot but we have travel left in this that bar down here because this has only about 10 to 50 miles of travel and then we set our 100 at eight and then we set our 180 degree stop like this and now we just move in and grind like this this will create the correct back clearance and also the 15 degree back taper that we need to cut or shape [Music] okay there we go that's the that's the 15 degree back taper and also 20 degree back clearance you can see a little bit of a facet down here that's that's the back clearance facet so next we just need to grind a little bit of clearance on the front but we can do that off hand take your cutter this side out here this is the cutting edge so we need we go in contact with the grinding wheel we tip it back and we tip it over like this and then we just grind until we're at the tip again very easy so yeah there we go there is our 15 degree dovetail cutter uh front clearance is plenty that's not going to be an issue but usually that's good enough you could also move the whole workhead around and grind the the front clearance with the machine but usually i just i just grind them off hand because it's a little bit quicker okay here's a close-up of the cutter that's the split surface this is basically from here to here three millimeters that's the 15 degree back taper here is it's hard to tell but there is a facet this is not completely ground around but there is facet and then there starts the the rolled off surface and the front as i said is just cleared in this direction and in this direction the clearance angle on the front are obviously way way overdone but it will do fine it will it will cut very nicely okay we're back at the middle set up the cutter set up the cutter in the spindle held in a collet relatively short running at 3000 rpm and i'm going to use a little bit of blue blue marker on here so we actually see what we're doing so let's let's take a little bit of a cut okay let's let's proceed on i went 0.2 millimeter deep in i'm going to take the same cut on the other side of the slot so my dovetail stays symmetrical in size this is not a trial and error until we get a nice fit on the blade it doesn't need to be crazy type because we're actually clamping it up against the upper surface oh there we go oh that that's that's almost spot on a little bit tight um i'm going to take like like 50 micron more then it should be a nice sliding fit oh yeah oh yeah i i i actually like this i'm going to keep it like that from this side yeah that's that's nice i'm not sure how what the tolerances on these blades are probably if i buy another blade it will be completely off but well that's that's just life but but yeah this is this is nice i hope this works nicely on the machine too well that's that's a beautiful finish okay got the milling done and put it back together and tried that out on a lathe [Music] [Music] it seems to work it seems to work very nicely i was a little bit worried that the way this blade is clamped with the screw from above and the blade being pulled up against this upper this upper edge of the of the slot that this might be too fragile or too too flimsy for for a insert a parting blade these parting blades have significant cutting pressure because the the insert has a very very robust geometry we will look at that in a second a bit closer but still still this is an m6 12.9 screw a high strength screw and this is designed quite quite nicely and this seems to be rigid enough to do a parting and steel what you saw in the in the short clip it was a piece of 35 millimeter c45.45 percent carbon uh steel let's let's look a little bit closer at the fit of the blade in the slot [Applause] okay close up time this is the parting blade this is the slot and this in here where the blue paint is removed that's the dovetail undercut that we machined and you can see that i need a pointier pointer [Music] and down here this is the back side of the roof shape on the blade this clears down here but up here the short section of the of the roof shape mates up nicely with the dovetail that's what's giving the clamping or holding power so that that's working quite nicely that's a nice fit and when we turn it around and when we look at the insert that's the insert and a close-up view this line here in front here this is the cutting edge by the way the light reflects on this edge you can tell that this is not a sharp edge this is definitely a radius now you can see it way better if this was a sharp edge you would not see this this bright line up here this this line up here you wouldn't see this if this wasn't that sharp edge so that means there is a radius an edge prep edge preparation and that's done to make the cutting edge last longer and strong and be stronger in general because a sharp edge is more fragile than if you round an edge over also we have this geometry in here this is to deform the chip and make the chip narrower than the slot we cut and last but last but not least it's a negative geometry this this small facet in front here this drops up to off to the front with a few degrees and this creates a very very strong angle between here and here this looks almost like 90 degrees and that's super super robust the problem is a negative geometry takes way more force to force it to to to push it into the material so there is there are pros and cons to this geometry but in general these inserts work very nicely [Music] and if you have problems with cutting pressure you can always come in go on a grinding wheel and grind then we have accelerated grind a chip breaker like this with a highly positive geometry that will make the insert cut super free and still roll a nice chip out there but the insert curt gets more french out that way but still that's always an option it's always an option to modify inserts okay here we go final parting tool blade i did some deburring and corner rounding on on all the milled edges but that was a nice little nice little modification to this otherwise to me useless multifix holder and as i said again as i said before ax8 makes a holder for parting blades like this with three clamps from the top that's definitely superior in rigidity over this one but it costs money some real money and one importer or reseller here in germany also has a made in china holder for parting blades but i prefer the axa holder here and this little modification was not too bad mostly i filmed it to show you grinding off the custom d bit to cut the undercut the the 15 degree undercut so i think we're done here thank you all for watching thanks for the ongoing support either by email comments or monetarily on patreon stay safe and i'll be back you

Channel: Stefan Gotteswinter

Views: 46,886

Rating: 4.9602485 out of 5

Keywords: multifix, parting blade, abstechschwert, abstechhalter, stichelschleifmaschine, dbit, stichel, indexable parting blade, werkzeugschleifmaschine, dbit grinder, single flute cutter

Id: rsP9axVNJOM

Length: 38min 49sec (2329 seconds)

Published: Sat Oct 24 2020