CNC Machining Overview - Large, Flat part with Bolt-Through Second Operation

[00:00:02]Welcome back to the mess everybody.

[00:00:05]I'm making some parts in the mill and they have a different process than most of my parts. I think there's some interesting nuggets to share. So, uh anyway, this is the part here. This goes into the frame fixture that I make and it's a 1x8 in extruded 6061 aluminum bar stock makes this part. And so for the first operation, I clamp it very lightly across two vices. And I machine the top flat and I do corner round and chamfer, drill and tap. And then uh up two, I bolt through into this Pearson pallet system fixture.

[00:00:46]And uh I finish it there. It's only a couple minutes per side. Uh but you know, a little bit fussy. And um but anyway, so I'll I'll uh show you one cycle of swapping these parts out for the next operation as we talk through it. So uh going to crack this loose and you'll see that it's shifted a little bit to left of center of these two vices.

[00:01:15]So you pull up on this plunger and that releases this.

[00:01:20]And um it'd be nice to put some handles some handles on this or something. I don't have those, but um I I only make a handful of these parts every year. It's not a volume thing. So, uh I just haven't gotten to gotten around to adding the handles, but it would be easy enough to to drop this, which would be bad day. So, it's like, you know, it's wet with coolant. You could slip and drop it easily enough.

[00:01:45]So, I use five. I believe these are M10 screws.

[00:01:55]And uh this there's a mirror image of this part that I also make. And so there's another bolt hole here if I'm making the uh the other version, which uh these days I don't even make that one anymore. But all right. Got to be careful not to let the uh tips of the screws drag on the part as you're lifting on and off. There's a key here on the back that locates in position uh in the assembly that this goes into, but I also built that into the fixture.

[00:02:24]Gives me pretty good positional um location of the part to use that key.

[00:02:30]And so I'm going to take this one and it's labeled. It says drive side out cuz I said I make a right and a left hand.

[00:02:35]So drive side out and drive side in.

[00:02:38]After 5 years or so, I learned to get smart and I started labeling those. uh which really helps later when I'm doing uh laser engraving and uh I I engrave those on the CNC for uh angular scale and some other stuff. So uh when I go to build them and ship them into assemblies, it's nice to know which one is which without thinking about it so much. Uh now this one is cracked loose. Now, uh, people will say, you know, if you want to make a really flat part, uh, don't use extruded bar stock and don't, uh, clamp it in a vise. I found that these actually are exceptionally flat. I've measured a lot of these on the surface plate with an indicator. I think if you go about it the right way, you can make very flat parts. I torque this to 13 ft-lb, uh, which is nothing. But because the facing pass is light and there's very little like lifting force with the face mill because the endmill is going slowly and it's just cutting shallowly shallow.

[00:03:42]All the cuts are pretty lightweight and so you can get away with a very light pressure and because you're not really putting much clamping force. It's not bowing or contorting much. It's mostly unconstrained.

[00:03:53]And then for the second operation, it's bolted through to a pallet that's really quite flat. And the result is very good.

[00:03:59]And uh if you sweep if if if I set this up on my surface plate on three points such that the bottom the bottom side with an indicator is uh like you know level to the the plate, the top side will be within about you know 5 10,000 of an inch uh maybe a little bit more than that on some but it's pretty rare.

[00:04:19]They're they're really pretty flat and uh pretty consistent on thickness um over their their size and length and um that's definitely good enough for for the application in my opinion. So, um you can do good with this sort of method. Very lightly clamp the part and uh and then bolt through for the second operation. And in fact, I think vacuum holding would work better. I don't know that it would produce a flatter or a less flat part, but if rather than using the bolt through method, if I had um if I had a vacuum fixture, I just think it would be a little bit easier to load and unload parts. So, if I had to make a thousand of these, I would find the bolt through method to be kind of tedious, but I can feel it seated there.

[00:05:06]All right. Sort of star pattern my way around.

[00:05:13]And then this uh you know, if you've seen the Pearson videos, the ball detents pull down and they seat on these pads. So, you know, every time I I'm ready to load it in, I just like to give it a wipe and make sure. And uh and you could load this the wrong way. So, I'm just, you know, I'm the owner operator.

[00:05:31]I'm careful with this.

[00:05:34]And I'm looking at these pads to make sure there's no chips.

[00:05:41]Wouldn't be a bad idea to blow those off. So, uh then I hit this button. I've had it before where um it didn't actually seat all the way down. Like one of the ball locks pulled down and one didn't because it wasn't seated all the way. I think if my shop air pressure was a little higher then it would pull in those balls better. But sometimes uh my compressor is on the lower end of its range and um that could use a little bit more. But if you just push it down it's fine. And uh and then yeah once you once you lock that in then the air is gone and it's held by spring pressure. And actually, this has such a good hold, you can rough really hard. I used to rough harder and it would actually vibrate the plate against the fixture below it, the Pearson pallet base. They would vibrate because I had so much lifting force from the endmill as I was roughing this away.

[00:06:31]And uh kind of interesting. Um, this has a lot of downforce with those ball locks, but uh the pallet is kind of big and so the further you get away, the more lifting leverage you have against the ball locks and it is possible to chatter this plate against the base. I learned I was cutting pretty hard though, you know, 1/2 in roughing endmill and I'd be up at, you know, I don't know, 60 or 100% spindle load or, you know, I was really pushing it cuz you got such a good hold on it, you can actually rough pretty hard.

[00:07:02]Okay, now I'm going to set in the next part and uh because I like to do a single piece flow. So, you know, op one, OP two at the same time. I don't want to get ahead on off one uh and then have a pile of inrocess stuff. I like to finish them as I go, you know, lean manufacturing thing. Uh most people are aware of that concept, but anyway, um this is kind of an illegal use of this orange vice, and it's kind of unusual.

[00:07:26]the uh the part is gonna clamp between the back side of this jaw and the I guess the front side of this one. And so these Carve Smart jaws have this dovetail. And uh the vice is going to clamp in here. And I'm pulling backwards against the dovetail, which is like an illegal move. You're not supposed to do that. But I'm clamping at 13 foot-lbs. I think it's totally fine. But I wouldn't I wouldn't want to reef on this. I think I would break something uh if I if I did that real hard. for because I need to clamp this so lightly. That works. And these vices have a fixed station in the center and then uh moving jaws. Um so you can Yeah. Anyway, moving jaws on either end uh with a common lead screw from the front to the back. But the problem is that if I pull these fixed jaws and I move them back here and I repin and that's a lot of screwing around. This for me is easier because these I don't I never move these. I I haven't lifted these fixed jaws off the center. Sorry if the camera is pointed wrong. I got to like tilt my head in the right place. Uh, but anyway, I don't lift these off of the vise. These stay pinned here. It's probably been 5 years since I pulled those off or something.

[00:08:33]It might be rusty underneath. But I just do all of my jobs without moving these.

[00:08:38]And this is one of the tricks that I've done to make that happen. Um, so it is cool that these are reconfigurable, but it's kind of a chore to move them around. So, so I prefer not to. So, here's the next blank. I pick this up and set this down.

[00:08:54]And then visually I'm going to center it. I think I pointed out in the beginning that I was sitting like this, but I'm actually going to center it right now visually roughly.

[00:09:04]And just close the vise with no tension.

[00:09:07]Grab my torque wrench. 13 foot-lbs on this guy, which is nothing, but the torque wrench allows you to be very consistent. And then I got to change my program.

[00:09:22]C2 tube plate DSO op 183 is my program number and cycle start. So uh actually single block and let me just wipe this down for you. Maybe we can kind of watch this.

[00:09:39]Jeez.

[00:09:42]Anyway, uh hopefully you can kind of see [clears throat] this. So, uh, in the beginning, the probe comes in and we find the part and, uh, you know, not not terribly hard to do this. Uh, but anyway, that just allows me to I don't have to screw around with a work stop. I hate work stops. You know, if I was making 50 or more of a part like this, obviously work stop makes a lot of sense. But I make these eight at a time very rarely, you know, like once once a year or something, once every 6 months.

[00:10:10]This is going to air cut. that I did because I would sometimes get an overt travel. I'm right at the edge of the table and uh I was tired of getting an overt travel and having to restart. And if you get the overt travel after you've started cutting, sometimes you scrap the whole part. So I just added, you see, that's the extent [music] of travel. So I just added a little tool path at that extent of travel, air cutting, so that if it's going to overtravel, it overtravels before I even start cutting.

[00:10:38]Adds 5 seconds to the [music] cycle.

[00:10:40]It's a little insurance policy for me so that if it does overt travel, I'm right here still. I haven't walked away and it's [music] before I scrapped the part.

[00:10:49]So anyway, these are really light cuts, you know, 17% spindle load. A lot of that's just the resistance of the bearings and, you know, air resistance, whatever it is that uh the resistance that it's fighting. But we're going to cut the top side features. We're going to face it out. Chamfers, drill and tap.

[00:11:08]And then uh and then yeah, I'll uh before I run that pallet operation, I actually loosen the vise and I slide it over an inch and just reclamp it. That way I just don't have to worry about the facing tool paths on the pallet uh bumping up against this part, which normally it wouldn't, but because I'm not working using a work stop, it's inconsistent and I rather just move it over a little bit. Anyway, uh so it's going to cut this part. I don't know, it's 4 or 5 minute cycle, something like that. I'm not not speed racer here cuz uh I make so few of these. And then the the other side actually removes quite a bit of material reasonably quickly. Uh because um you know, I got such a good hold on it, it's a reliable uh it's a reliable way to rough the material out.

[00:11:50]So you could uh you could get these water jet blank from plate, but that would be more hassle at the volume that I do. a lot easier to just get a 12ft bar, bandsaw it up, and then make them complete. Uh, but yeah, there's a lot of optimization left if you had volume. You could uh reconfigure the part. And that was kind of my thinking when I designed this process was let me get something that works and then if I sell a ton of these, then I can solve the problems.

[00:12:16]But, um, frankly, I I don't sell a ton of these and I sell fewer every year probably. So, uh, might as well just stick with the system I have. It's it's pretty good now. And uh yeah, I think I think this is the end of the video. I could I could show more, but this isn't really that good of a a shot. So, I just want to share some of my thoughts on some of these pieces of equipment. That Pearson pallet there is a cool idea and it's a cool product and uh Jay shows it off well on his YouTube channel. That's not my favorite piece of work holding. I just don't have that many parts that make sense to use that uh that Pearson pallet. Crank it up to 100% here. Um, but yeah, I I do think the Pearson pallet is good for quick changeovers.

[00:12:58]It's good for bolt through stuff. You can do pallet fixtures with fixture clamps, but as I've said in other videos, I'm not really a fan of fixture clamps. Uh, they're just kind of tedious and those pallets with all the fixture clamps end up being kind of expensive.

[00:13:12]So, um, it it's a very specific type of volume and part where I'm actually motivated to make a pallet fixture. And I have that fourth [music] axis. And frankly, making a pallet fixture to hold a bunch of small parts or making a fourth axis tombstone to hold a bunch of small parts. I would rather make a fourth axis tombstone. It's a similar cost or possibly less. And it's more flexible because you get the fourth axis positioning and you can yeah fit a similar number of parts wrapped around a 5x5 tombstone cube. So, uh, I'm big on the fourth axis. Whatever. I'm just rambling. Just wanted to share this setup for making these [music] parts.

[00:13:52]And uh that's the video.