ROBRENZ TOOLROOM TIP #1

hello everyone bumping my shop I'm Robin today I'm going to be showing some [Music] grinding tricks on using a spin fixture and aligning a little part a lot of little details that might be helpful so let's get to it here's our little pieces these are a two they have a counter border in them for an m3 screw with a reduced diameter head and these are currently straight made from quarter inch diameter or drill rod and then vacuum hardened and tempered and here's one that I've ground and these need to be ground with a thousand and a half diametric taper over the length of these so I have my spin fixture sitting here tilted at that angle so that part is taken care of as far as the taper no magic there other than I putting it in the vise and just told you the vise as opposed to putting it on a sign plate for when you're around that vise is quick and you can tap it in to get exactly what you what you need is far as taper one thing I've done to the spin fixture is I've taken a screwdriver a Ryobi screwdriver and taking all the guts out of it and just made it basically just for this put a mount on there where they can be removed from the spin fixture if necessary there's an actual bearing in here that I takes the radial load that's on pulley so that it's not on this and that little hex you see there is actually going into the hex drive and that's what's driving so this pulley is not pulling on the on the drivetrain but it is using the natural reduction that is in the in this drill driver and it does have a two-speed gearbox pulley made to replace the the actual crank that's on there and a heat sealable urethane belt that's from McMaster and just heat sealed from that for that distance down here I'm driving it with a variable voltage DC power supply that we just use the button here to control my speed so it allows me to just rotate the thing around for indicating purposes without any trouble here's the spin fixture and I have a piece in here that's also quarter inch diameter hardened it's been drilled and tapped and three in the end and what I have on here is an actual inter race of a quarter inch bearing and I've ground a solid through it with us with a dremel disc but this is a snug fit on here it's very grabby and you'll see where I'm going to use that to rough align the piece one thing that is very important with the block work and that is to realize that when you're clamping things there's always Distortion doesn't matter how lightly clamp whatever you're doing things are moving so one of the things you can do to help this the block and this part actually runs straight such that these this axis is parallel to the axis of rotation is to use a very thick backup block so that you're putting a uniform linear pressure over the entire surface and also such that it's actually touching with the length of the V block if we come up here and look at the at the V block we see that this is relieved in the back and that's where the these stops down here also having the screw centered axially between the distance here of the engaged V block is important if you move that screw to the front it will tend to tilt this piece downhill if you move it towards the back it will tend to tilt this piece uphill so every little nuance there is extremely important when you're down in the tenth and sub tenth work you have to think of all these things as being rubber and responding that way so this is indicated in to run reasonably true this face on the end has been ground with the edge of the wheel such that it's running true so the facial run out of this is minimal it's just whatever bearing run-out is in this in this head so this face is running very true because it is the only reference that this part has this parts going to be screwed on there with a screw and that that interface right is what's actually holding that part true so this OD really isn't all that important because I'm going to be indicating these individually and showing you the techniques and one of the special things that's very important in in doing this since we're expecting this part to be able to translate on that mounting surface smoothly in very small increments you know tenth increments this original as turned face we have to be very careful to get rid of the turning marks and any burrs or nicks or anything that are on there so these have been I have taken these and just giving them a good good hit on the precision ground flat stone and basically what that's doing is putting a gauge block type finish on the face there that can easily translate you can see the shine on there it got rid of all the burrs and that will be able to easily move on the mounting face that we're building up to to so anyone who's ever done any mounting of something like this using a screw to mount something and tap it in and then tighten the screw to hold it tight will tell you that it doesn't work as well as you'd like because the irregularities on the on the shoulder of the screw the irregularities on the counterbore how perpendicular or parallel they are when it clamps up all means that when you go and give this you've tightened that you tap it all in is running in the 50 millions and then you go ahead and tighten this as tight as you would tighten it to make sure that you're gonna be safe to grind and it moves it pushes it off-center and you can just about guarantee the number of times it's not going to do that is just yeah just didn't go to have it so this is the piece that is part of the magic to put in your your tool room arsenal is when you have something like that that you need to have not move when you're indicating you make this intermediate piece and this goes in and acts as the counter bore the m3 longer m3 group passes through I have this next distance here is just for grinding wheel clearance the knurl is so that what I'm doing is when I go to tighten this after I've already snagged it when I go to tighten this I resist the torque I'm applying with this hand with my fingers here so I'm actually going to earn I'm I'm I'm twisting counter twisting such that there's no relative motion between this and the part therefore there's no you know nothing scuffing this around trying to push it around it's pure axial force and I've done 50 or 60 of these with this way and this basically does not move everywhere I've tightened every single one of them that way and they stay right words indicated so I'm going to demonstrate that on the piece here clean my part surface clean my arbor surface put the screw through the whole assembly slide my ring up until I start to engage my part try and do this where my fingers aren't in your sight I'm just sliding up onto the piece the part is a little bit bigger than the arbor so I don't want to slide up too far I just want to get enough where I'm just basically aligning those pieces and just putting the gentle pressure on there just enough that it stays put as I indicate now I just drive right onto the indicator I don't have to move indicator sitting where it needs to be it stays there for all the parts and now I'm going to zoom in a little bit here closer so you can see the indicating a little bit better and I'm using my voltage knob down here on the bottom just to drive this look find my high in my low stop on the high try to get roughly halfway a little bit hi there I went before I did a little bit there that's about tenth now the magic is to hold this counter torque with my these fingers right here my my left-hand fingers as I tighten with my right hand fingers what I'm doing is I'm keeping this from rotating whatsoever the screw rotates on here I'm - I'm absorbing the torque the drag torque between the head of the screw and this transfer part between my hands so that that's why there's no relative motion happens to the part now if I've done it well this should be so within a pen guy exactly what it was okay so that's the this can be all different forms this just happens to be the form that works here but the idea of having something where you can hold it still so that as you tighten you get no relative motion no rotary motion between the mounting face of this and the part is what lets you indicate this in now this I have such that I can now drive don't have to touch you indicator don't have to move it it can stay there through all the operations now I just drive here and I'm gonna fire up the grinder and we'll just show the grind zoom in here I'll just show you the grind where we just go in tangential I don't have to traverse sideways at the draining under there turning the rotation on now just some drive-in and you'll see the drying start to progress from the end because of the taper and as I go deeper so I'm at the low point Gardens it off a little bit so it climbs a little bit now I'm just gonna speed down until that cleans up truck there that little bit of variation you see is actually that little bit of residual run out that tents it was there when that's done working out I just drive out you take a look at what it looks like run out lies here where we where we drowned and this is now the run out fits there gets the residual run out of the grind head so the several points just reminder of what we're showing here one is having the indicator and the grinding wheel all in the same location such that I don't have to use that indicator at all from part to part the part to get any torsional motion on the face of the part to be strictly absorbed by the screw between my fingers and this Merle ring that's why it's got a nice fine diamond girl on it the sleeve springy sleeve that'll slide over to get me in the ballpark so I don't have to tap it around you know mile and that's it so I just thought that might be of interest to you guys and see some techniques for being able to tweak something that you're mounting with a screw

Channel: ROBRENZ

Views: 51,765

Keywords: grinding, indicating, spin grinding

Id: OcSAIRhDrGE

Length: 12min 7sec (727 seconds)

Published: Tue Jul 24 2018