Toolmakers magnets - Part 1

so welcome back to a shop today we have a mixed stop ik we have brass we have some new ten new magnets and left some mild steel and what what we are going to do is at work we have magnets that are laminated out of ferrite magnets and brass and there are surface ground all over flat parallel and square and there should be useful you can use them to hold small parts on the surface grind over the the pole pitch of the magnet check is two cores where you can use them as a stop on the wise on the side of the wise as there are surface ground they will perfectly line up with the side of device there are hundreds of uses for them aligning parts for for assembly hands on and on they are quite expensive you can buy them from most tooling suppliers for about 300 bucks a pop and there are 25 millimeters square in cross-section hundred millimeters long so I'm not willing to pay that because the materials are almost dirt cheap you can get with a handful of these rather strong neodymium magnets for a few bucks on eBay the problem with these is they are quite brittle it's almost impossible to machine them with a with a hand mill or on the lathe and when you surface grind them they make first of all you get a pretty impressive spark shower because the material of these tends to be quite inflammable when dust for more grinding dust form also when you run an end mill into them they you're up for a surprise and the other problem is they are coded with their nickel-plated and when you damage the nickel plating they corrode and oxidize with the oxygen in the air and they will degrade over time so best thing to do is not to touch them in any way this one is already chipped from me playing around with them and let let them snap together that that tells you about something about the brittleness of these guys so I came up with another idea first of all when we take such a magnet and when we look at the field lines they are polarized so the top side is north and the other side is soft or vice versa don't know which one is which look at my good cat drawing here basically if we have the magnets just sitting here the field lines go out like this just all those B faces but if we place a mild steel plate on the end of the magnet on both sides of this magnet the field lines don't go out the side any more show you with this see almost no stick tivity but on the faces here we got very very high forces even more on this side because the surface area is bigger almost hard to get up get it off and on this side you can barely lift the part a post to the naked magnet which is in this orientation almost very hard to get up without having to pry it off so what we will do is we will make a plate out of brass with two holes in it there will be two magnets in it and it will be covered on both sides with a piece of mild steel which acts as a pole plate to direct the field lines out of the side of the magnet so you get full holding strength on the on the other faces of them of this stack up but no magnet fuel lines or magnet force on this side that way we get a very even very powerful magnet placed I hope we will machine these brass plates these mild steel plates from coat drawn steel you want a very low carbon steel for this purpose so you don't get a lot of residual magnetism soft iron or transformer sheet metal does it's basically raw I've written with nothing in it would be perfect but it's hard to get so Coke chrome steel we'll have to do it and then we need a stack up and we will glue it all together and certain machine and surface grinders all over which is not a problem because there is no exposed magnet to the outside we only have the brass plates between and the brass plates with the magnets in them and the mild steel pole plate between them but right now as I think of it I think we are going with one magnet not with two because there won't be much meat left to the side to square up this block which you have to do after after some time because these mean everything on these magnets is soft and they will get dinged up and yeah they will be we are surfacing them at work pretty much every year to get them back in spec so let's start with these chunks of very rough brass that was all bandsaw cut on all surfaces and square them up and see if we can get enough material out I'm aiming for a length of about 60 millimeters and that means we have to do seven seven of the brass plates and eight of those sheet metal plates eight because we want a plate on both sides of course let's go and we're going with one magnet just decided okay now we're all at the milling machine with the rough piece of brass clamped up and wise and then using a fly cutter to clean up the surface which works very well the problem was the fly cutter is the chips fly all over in the shop and the next setup I decided to use man mill here you can see the finish from the fly cutter we put this machine surface against the fixed job device and to square up the part I'm using a ball bearing ball that has a flat ground onto it that's between the movable jaw and the piece of breath the flat on the ball bearing is so you don't put a dent into your wife drop as you can see by the surface finish this end was pretty much done so I change to a 10 millimeter 6 flute carbide end mill which did a way better job then I flip the part around sit down Perlas nice and tight and machine to the other side parallel to the first side that's pretty much my standard procedure to square up material that have no square surface at all the ball bearing makes it very easy to get Singh Ling's square as to material was pretty thick and I didn't want to machine away all the brass which is quite expensive material I decided to use living saw and slice the piece opting in thickness so here I'm running the 63 on either slitting saw 100 meter thick through the material but cutting death was not quite enough so I have to go on both sides to cut it apart completely the first side this went quite well and as on the back side I didn't have big problems until the end where the blade deviated about half a millimeter and I blame this to the saw blade itself because it was not brand new and I used it on steel before quite a lot the mill is perfectly in trend but when the saw blade is not cutting very well you get problems like this and I changed back to the six-foot carbide end mill and cleaned up the surface and machined it also the thickness normally I wouldn't use it excludes coded Antonella on brass but this was the only big and no that a hand in hand okay I got the two bars squared up and two thickness not super precise but they are within dimensions and now we need to cut them to length but before I do that I face off the end on both sides and I will cut off a slice reface the remaining stock I do that so I have always a reference surface on my stock before I cut it off and as this is a multiple set up I have my two parallels and I will drop in a spring between the path so parallels don't fall out or get sucked into the cutter which stuck because there's a quite expensive new six looter I would normally use this only on steel and finishing cuts but in this case it's the only bigger brand new end mill that I had and then absolutely not fighting about the finish in this case I just want to clean it up as much as possible now we cut off four pieces one on each end and clean it up clean the remaining stock up and cut the remaining parts just just use a heading to blew up the surface slightly so we see our layout line there are two ways you can layout with a caliper you can use it like this like a scribe this ruins the measuring legs here what I want to do for our longest time I wanted to take a caliper shorten one one of the legs machine out a small notch and braze on a piece of carbide so it's dedicated scribing caliper and the other way is you you can use this edge and this edge for for a layout like this just use your scriber and hit the part like that it would help if you just blew things wide enough and yeah this ruins the caliper too and you shouldn't do this at all but this is my not so good or this is a meter to you but it's not asked that accurate as it should be anymore it's at seen its fair share of use and abuse I bought the second-hand and it's it's lovely nicer once it has the prismatic we ways and it's parallax free there is no gap here or steps so you can look on it in every direction they don't get the parallax error like you would on a normal caliper these are horrible expensive but as set this has seen better days and I use it only for minor work my main calipers of course the Diggy mattock the dramatic digital me too so now we can cut this down I think I will do it with a hacksaw brass always calls for a brand new blade that has not seen much use otherwise you will just skate across the material brass is bearing material not a very good one but this is a bearing material and done if this saw blade or the cutter is dull in any way you will slide over the material here we are preparing the steel pole blades which are already milled on one side and cut to length and shoot and I'm just squaring up the second side pressing it down the parallels clamping it running mill with power feet and in the meantime I'm deburring the second part or the part that I'm a machine before compressed air makes it easy to keep the setup clean so you don't get chips under your heart okay you saw me just machining down the cold rolled steel to be also square and parallel and this is how the stack up will look like steel brass steel brass Samsung is on it we will end with a steel piece again right now what we have here is a magnetic parallel that we could use under surface grinder if we connected it all through and made it one solid block so we will make a we will make a set of parallel blocks and magnetic parallels for the surface Brendan another video I like the laminated version more than the pin version more common here but this will get a precision ground magnet so we'll take these brass blocks and drill them in the center by 8 millimeter diameter so we can glue in these need ending magnets then we will end up with an hopefully awful strong magnet that we can grind on all surfaces so let's drill these brass plates but brass has of course the property to be very brittle and it tends to grab the drill once you poke through the other side of the material danda the drill bit will screw down into the material just like this we're about the part out of ice and yeah you know the story sitting in a corner crying there is easy fix to that you want to make your drill bit a normally it has a positive rake a rake indicated by the spiral angle and you want it to be zero degrees so you take a small triangular stone and you lay it flat into across the main cutting edge here tip it you will find the alignment to right alignment and get a few wipes source of stone both cutting edges of course and this very small flat spot is enough to keep the drill from grabbing your real drilling with the modified 8 mil your drill bit and as you can see there is no pre drilling no Center breathing I have to drill pretty short in a collet and I can drill right through without any major problems if you would use a drill bit that's hot that has not been modified on the cutting edge rest this could lead to troubles you will catch your work and the work will get ripped out of the voice okay I get the stack up put together on my my small lapping plate just as it's a flat surface and after magnet just push into the brass plates it's loose in there and after Steel Pulse plates on both sides and I stack them up completely against each other and seems to work just work pretty well just this piece has about I've no idea one or two kilograms I'm horrible at guessing weights but as you can see this is a pretty strong magnet stack up here and the TAS know magnetism or pretty much no magnetism at all on the ends only on the on these surfaces which we are interested in so next that will be to clean everything mix up some quick set epoxy glue down together and I have to keep in mind the magnetic force of this will increase one we surface grind it because the quality of a surface affect the stick tivity of the magnet to another surface in great a great matter let's see we have this is some way of changing welds down here which we won't use we will use this stuff this is basically a five minute epoxy without any filler there is one thing with the stack up I'm not sure if if you only do you alone will hold this together I'm tempted when we glued it up that I am going to drill through foreigners threw a whole stack up and riveted together with long brass pins maybe we'll do that but maybe it's not necessary let's see let's do the glue up okay I wrapped by my small lapping plate in sarin film so I don't get the epoxy stuck to it now it will mix up a small batch 55 minute epoxy and try to assemble the sky without making a horrible mess on my workbench that's pretty much this stuff is not very critical with with the mixing ratio there we go that should do now we will start out with piece of steel piece of brass and I mark the polarity off the magnets on here with some with a netting and I already went through the procedure how to do this on doing a small dab of epoxy onto the magnet then I shove it in and we drilled them pretty close I realize we might have to use a little help but before we do that I will mark the polarity on the brass - like this now we take a small we go piece of paper wipe off the excess shouldn't be necessary because we were having applying more anyway I would take our first steel plate cold plate spread from epoxy on it and pink there we go try to align it take our second pole plate of steel plate makes it sound much more massive there we go try not to get a piece off glove stick stick it in there so now the next magnet has been the opposite orientation otherwise you lose holding strength at least that's what I found due to experimentation so we'll take our next magnet place it in a bread piece of brass check the polarity mark it this should all go bit faster because the epoxy setting setting up and now we have to oppose it that way just small Bell DF proxy and together okay the epoxy has set and it's all holding together and we have a lot of squeezed out of course but we should be able to machine this down to be roughly squared up then we will drill through in two corners and put in two pins to give it a some additional strength

Channel: Stefan Gotteswinter

Views: 140,571

Rating: 4.9008694 out of 5

Keywords: magnet, toolmaker, brass, neodym, milling machine, toolmaking

Id: HBhnRvCnIcs

Length: 24min 40sec (1480 seconds)

Published: Tue Oct 25 2016