Soft jaws for machining plastic parts

[Music] hey welcome back and I have a good amount of these plastic parts to machine OD ID and CNC milling and for the ID Burke I have to take off quite a bit of material and I wanted a secure way to hold them and normal normal outside steps free jaw chuck jaws what a word have not very much surface that holds on to the part and when we take a quite heavy cut like any hole whiff of an insert which is in PVC not a problem at all it can happen that you lever the part out of the jaws and proven create a quite entertaining crash so the better solution in my mind or pie jaws like these they're basically soft jaws with a huge contact area to the part and they're easy to make and work beautifully I have a set of master jaws never can bolt anything to that I want so let's go to the procedure of making them and yeah look at the cat cat and cam kept them out on the CT router and go from there there we go that's that's a very solid grip no no worries that this part will ever come up during machines here we have the PI jaw starts out at a piece of hundred millimeter aluminum and we machine those features here Ian those match the master jaws I have the way I modeled this is I have a sketch here which has basically every single dimension in it which looks quite messy but this way of modeling has some advantages then you just go back and pull ever dimension out into extra model with all the solid features and we go into cam and I have to to separate all the programs for each I have to do extra operations for each tools and I have to do extra setups for each tools because I do not have a tool chain around the machine and and it's the easiest way to do it for me so I have set up for 4 millimeter and mill 2 millimeter and mill and down here is gem friend mill the way I do is this I cut these areas that are accessible from the outside as a 2d profile just entering from the outside and slotting them out and I have a 2d pocket here spiraling down and then just pocketing it out 2d contra finishing those profiles to the counter finishing this inside profile to the pocket finishing the bottom surface of this feature and spiral milling those counter bores the 2d the 2 millimeter tool only cuts those three slots these slots only have to are there so I have a guide when I cut them through with the bandsaw and last but not least chamfer and mill 2d chamfer walking all the way around to chamfer depart so let's hit simulate with this material not not trying the tool path there you go there we go that's all all the features cut that's the chamfer end mill obviously I didn't take the stock from the previous operations over in the other because it's not necessary for so simple processes I'm set up to cut another one of the pie chart on the CC rather have us reach our tractor clamp to the table I have a formula to flu carbide end mill in here I do not have a tool changer or a tool to length probe or something like that I do it the old-school way with a streamer stream millimeter gauge block and touch off manually the way I like to do is I jog down until I can can't get the gauge block under the end mill and then I clock up in one hundredth of a millimeter increments until the gauge block slips under the end mil like this then my offsets to the top of the part is three millimeter and I prefer to have to offset off my my birkoff set on top of the part I know a lot of people put it on the other side of the part on which will be the bottom of device or the jaws that hold apart but I have been burned by that before I prefer it top here program is loaded I have street tools four millimeter two millimeter and a chamfer meal I've screened with your programs and let's go [Applause] this is slightly different from the machine at work at work I ran an ad a Tron and 10 pro with 40 thousand rpm spindle Renishaw probe and two length probe and the 22 station tool changer for hsk 25 tooling that that machine makes quick work this here is way more raw and way more basic but it gets the job done and basically basically I bought this machine for run specific specific job and paid already for itself so me and when the moment comes along and I find a cheap tool changing spindle for this machine I will throw it on here changing to a two millimeter carbide end mill I'm actin Weston and you brush Sunday and another tool change these are not exactly dmg linear machine to changing times and there we are finished bottom side of the soft jaws these are the slots that register into the master jaws and this this part here indexes them on them over at the manual mill drilling the PI jaw I'm using on this is an outer race of a ball bearing as a parallel because it's round nice and nice and useful I've just clamped the round block and the wise without bothering for alignment I'm just lining the drill by eyeballing up with the pre milled holes I put in there and because I don't want the part to tip over I put a screw check on both sides just to be on the safe side when I do the drilling drilling puts a lot of axial force in the part and you do not want to tip it over no test this isn't these are just clearance holes for screws so there is no high precision vault six point five millimeter drill for an m6 crew that's plenty of clearance first I've done now we're gonna take all the stuff out of the price change to a pilot that counterbore because these don't help much if the screws are on top of it you want to sink the screws in very deep so you have a lot of meat of the god machine away but basically I want to leave about that much material setting my depth stop and dropping it in and in this case it's even easier as the pilot tool I just line it up drop the wife's handle clamp it I'm good to go nice thing about aluminum is is that it can run the tools crazy fast next one and I'm using alcohol to prevent the tools from ceasing up and aluminum Oh medium whatever not because alcohol is a great lubricant but because it is a pretty bad lubricant but it evaporates and leaves the clean machine afterwards [Music] and as the CMC made us nice nice lines so it can dance at a part that's what they're going to do be careful when you when you cut from when you have a round disc and you cut in from the outside stresses in the material will pull the cut shut and it will have a hard time to get the bandsaw blade out so as I saw I didn't kept all the way in I marched my way around and increments we went Florida in which makes that the stress is around the round part can keep in a can be kept in a balance that way and you're not pinching the blade on the first one I cut and I kept all the way to the center and the cut closed completely on the end and that took some maneuvering around with two bandsaw blades to cut it out again but this walking your way around it works pretty darn good I'd have to see so there is my there is my second set of pie jaws I will mark them with with a number so I can keep them together and do not mix them up [Laughter] deeper ringing the soft jaws I don't want to cut myself on the sharp edges here it's nice when did yours I will not raise or hope where you're more than cut them whatever did to them but are nice that smooth to the touch well let's see piece of PVC and this is this is a secure setup this this part is not going anywhere yeah this is rigid I like it by the way this is the second lop I was thinking that you might be interested in this fixture - or in the setup ever not here and the washer seawater which is basically just a piece of PVC scrap with a slot bandsaw in so I can slip it over this and made stuff and the slot is there so I do not have to unthreat this nut each time I change parts over and apart it's just a snug fit on this and this disc of Delrin bolted to my to a faceplate this is bolted with two m8 screws to a faceplate turned true and to a close fit on the inside of these PVC parts and I slipped this I slipped the PVC part over why not actually do it with an actual part slip the part over it make sure it's resting against the face get the washer lock it do not over tighten it the part can't can basically not go anywhere this is a very safe and rigid setup and also very repeatable and very precise each time and you can do something but Ann Arbor and I register chances are pretty high that your the results will be quite precise the only thing that's annoying is with PVC it's really hard to break the chip I'm using polished aluminium aluminium inserts CCM tio 602 and I've tried feeding them with point three millimeters and then they start to break the chip but below that you get this this thousand meter string of chip if you have to handle that's also the reason why I run it so slow if I run it said that's slow the chip just falls off the leaf and does not grab itself around the Chuck and the part and the tool and messes everything up so yeah that's the joys of working with plastics I was thinking while I'm here I can show you what these parts are going to be anyway because you have seen it you haven't seen me do much teensy work on this new machine so why not show up a little bit after the parts are turned on the lathe like this they go on the CNC industry jaw and a machine these ratchet teeth on the inside complete machining is done with a four millimeter carbide ball end mil roughing and finishing which is not a problem PVC at all - where is doesn't happen in this material I already left with a little bit of fur on these edges here which are not problem because I'm hitting the inside anyway with scotch brite and you as you can see this is a normal Street jaw Chuck no soft jaws no oppai jaws and I do not get any any marking on the part here and the reason for that is I do not crunch down on this chocolate crazy I'm just tightening it down enough to hold the part during machining knock it down onto the horizontal steps of the jaws offset is already set because I machined the part already and okay here we have the part in CAD and cam as you can see I have actually two components I have the actual part with the saw teeth and everything in it and I have this thing here which will also serve as the stock model for the cam operation but also this is where they're going to make on the lathe that's all their patience I can do in a lathe without problem then I go over to the CNC router and have it cut the teeth into it which I obviously cannot do manually at least not without getting completely mad at myself let's change to cam and as you can see I have the the stock is the model that I did beforehand and we start by walking down with a formula in a ball end mil down the wall that's because of those round bosses here and would go down again with a largest step over for finishing and then we rough out the the pockets here to the pocket operation to rough out the salt 'if then it's quite simple just 3d contour same formula ball end mil and what allied finish everything which takes about 15 minutes I'm going to thousand millimeter per minute feed rate net roughly ten to fifteen thousand rpm the RP I mean here has nothing to say because I set the speed the spindle speed my CNC router manually depth increment is 0.1 millimeter then I have a drilling operation that just go sound half a millimeter on each of the holes to create a dimple so I can grill them open later on the mill manually not going to drill those holes forty millimeter deep all the way through on my sincere outer that would be a bit painful with with the relatively fast running spindle and the PVC is really material that tends to to gum up and burn and melt and create quite a mess so I'm doing that manually [Music] [Music] [Music] so they don't look perfect off the CNC rather I get a burr here that I could avoid with a slightly better tool path but why bother for six parts I will have to make a thing about 20 and total of these so I might optimize the tool path a little bit let's evens out all the two marks a little bit removes the fine fuzzy burr at the two Leafs and this very soft plastic I'm not a big fan of PC if machines okay it's it's very it's very soft but it's hard it's hard not to get a bird so that's better I will do a little bit more - I have two ball mail do me the center Center drilling because I'm not going to drill 40 millimeter deep on my seat see rather I'm going to drill these on the manual mill all the way through but apart from that I'm quite happy how they came out machining time on the router is about I think 30 minutes for all the for all the ratchet teeth roughing and finishing and I got a pretty good finish on the on the actual teef surface here and what's in C rather in the other room is finishing the PVC parts I can turn the double rim parts that go along with this job another in another set of my chart that I've turned right now I used them to exempt the part on the outside but later I will modify them so they clamp this piece which will look like this hollow on the inside I will modify the jaw so I can clamp this part from the inside and machine DoD and the face of them no there we go here you will see how well this chuck holds such a part even as it gets thinner and then around the walls we start by punching a hole screw the finished part will have a 12-minute hole anyway but I will do that along with all the other holes and in the top on the CNC router burn I'm just blasting through a 10 millimeter pilot hole so I can get with boring ball just a facing cut to clean up the face obviously and give me a serum [Music] [Music] there we go that's all that's stalled a massive material removal done and the first set up now I just have to take a grooving tool the 1.5 millimeter radius and cut an internal groove touching off on the face of the part offsetting by 1.5 millimeter which is the radius I'm going in when you move my stop going in 17 millimeters getting down with the speed a little bit it's around a 50 rpm there you go change to a three degree chamfer tool which is a weirdo but it works needs very low speed because I have very large engagement look at that chip almost like foil the drawing specs a nine point five millimeter wide chamfer that's a very open open tolerance I'm just checking it with scale that's good okay now I need to hook these parts from the inside like this and I'm going to take the same choice that I have a pre-loaded time in the center with a pin that I clamped on can you do this always or yeah make sure you always use the same opinion drive on your Chuck cause that way you always preload the Chuck the same way there is nothing squirming around if you if you always use the same one that's how this is the reason why you should use always the marked pinion drive when you use the stock hard jaws which I'm not doing in this case but I'm still using the marked pinion drive sighting zero keep track there you go now it just turned us down two hundred and two point three millimeters all of you guys pretty much were already screaming at their computer because I'm telling you all the stuff about your repeatability and using the same opinion drive and get a yeah the other but a pre little D Chuck in the wrong direction I pre-loaded it from the inside would you do when you want to do I Deaver but when you when you want to do OD work on an on soft jaws you need to preload it from the outside yeah so I had a had a large hose clamp and I wrapped it around I can preload the Chuck in the other direction and pull this pin out well now we are pretty little in the right direction and no this is almost not dangerous so this thing can bite you okay this should fit let's get this let's again this post clamp off there we go that's a nice widget setup hitting the edges with a chamfering tool and I think it's done last operation will be on the CNC router to drill a hole some mill out the center hole far apart from death there we go so this is a clear case we're making some specialized tooling in this case the soft jaws and the arbor makes the job so much easier to get done it's not always about having material removal rates and crazy high feed rates sometimes it's just about holding on to a part safe reliable and repeatable think about that though thank you all for watching and see you next time [Music]

Channel: Stefan Gotteswinter

Views: 35,580

Rating: 4.9660573 out of 5

Keywords: soft jaws, pie jaws, weichbacken, segmentbacken, kunststoffbearbeitung, lathe, drehbank, isel, isel miniflat, cnc, fusion 360, pvc, delrin, POM, weichbacke, softjaw

Id: 3cU1Bf4-EjI

Length: 34min 50sec (2090 seconds)

Published: Sat Mar 10 2018