Quorn Mk3 Tool Grinder Part 9 Cotters, Support bar and clamp

Added: 2026-05-27

[00:00:10][music] >> Hi folks, modeling Mark here again. In this video, I'm going to be looking at this support bar and this clamp. I won't be doing this part just yet.

[00:00:25]I shall also be doing the cotter pins that hold this clamp on the vertical shaft.

[00:00:32]First off is this bar.

[00:00:37]I made this off camera. This is just a half inch bar with a reduced diameter and an M8 thread on the end.

[00:00:46]Of course, it's shiny cuz I took a polishing mop to it. But well, you got to, haven't you?

[00:00:56]Now, I'll start with the cotter pins.

[00:00:59]These are a half inch diameter bar with a hole through them and a cutout so that it clears the vertical shaft.

[00:01:11]Now, if we go back to this drawing, you'll see we've got a 1 and 1/4 inch shaft.

[00:01:18]We've got a half inch hole through here and the offset from center to center is 0.802 inches.

[00:01:27]It's important that the cutout in the cotter pins is a 1 and 1/4 inch radius and the centers are offset by the same 0.802 inches, so they meet smoothly.

[00:01:42]Now, I'm going to start with the cotter pins. These are made from half inch steel bar and it needs a an arc cut in it, which is on a radius of 1.25 inches to match this bar.

[00:01:57]And the center of the arc has got to be offset from the center of this bar by 0.802 in.

[00:02:06]Same as we got here, the offset of the two holes.

[00:02:11]Now, I do this using a fly cutter.

[00:02:15]Fly cutter body has a diameter of 1.08 in.

[00:02:19]The arc we're after is on a diameter of 1.25. So, subtracting one from the other, we get a difference of 0.17 in.

[00:02:29]So, I Now, I take half that and we end up with 85 thou.

[00:02:35]So, what I've done is I've I've set 85 thou on my caliper.

[00:02:40]And now we've got this step.

[00:02:44]Which is nice convenient 85 thou.

[00:02:47]So, I can use that step to gauge how far out the cutter sticks. And that should give me nice accurate 1 and 1/4 in diameter.

[00:02:57]The bar's mounted in a square collet block now.

[00:03:00]I've edge found off the two sides of the bar and the zero is on the center line of the bar.

[00:03:11]I just edge find off the end of the bar.

[00:03:27]Now, I've got the zero on the edge of the bar.

[00:03:31]This cutter needs to be an inch and half long.

[00:03:36]So, it needs to come in 3/4 of an inch.

[00:03:50]3/4 of an inch, which will be the center of the cotter.

[00:04:03]And the offset is 802.

[00:04:08]Which looks about right.

[00:04:13]I'll round the table in another 100 thou and I'll slowly come out.

[00:04:22]All being well, cutting the arc.

[00:04:26]All right, so we should be good to go now.

[00:04:52]All right, that's the first cut and you can see it's just on my scribe line.

[00:04:58]So, so far, so good.

[00:05:48]off.

[00:05:53]Well, that wasn't supposed to happen.

[00:05:57]Uh, I've just had to reset that.

[00:05:59]Bit embarrassing that one, but never mind.

[00:06:02]So, we're ready to try again.

[00:06:25]Uh, sorry about the image stabilization there.

[00:06:29]It seemed to go very squirrelly.

[00:06:33]I've hopefully I've turned it off now.

[00:06:36]So, let's try again.

[00:07:08]That's come out nicely. Very good finish on that.

[00:07:12]The next task is to cut the double cotters in half.

[00:07:17]And that needs to be obviously halfway down the arc.

[00:07:22]Now, that arc is 0.75 in from this end.

[00:07:28]I've got a 0.8 mm slitting saw in the arbor.

[00:07:33]Uh, shop-made arbor.

[00:07:37]I've also got about 10 thou runout on this slitting saw. Yeah.

[00:07:41]So, I'll bring the slitting saw down until it just touches there.

[00:07:47]Then, drop it by.75 in. Then, I'll drop it by a further half the thickness of the slitting saw and half the runout, which is.4 mm plus 5 thou, whatever that works out at. Calculator time.

[00:08:08]So, first I'll just gently bring this down so it just starts to touch on here.

[00:08:13]Running on the slowest speed possible.

[00:08:26]There you are, I could just hear it start to rub.

[00:08:30]DRO zeroed.

[00:08:38]Slitting saw's got to come down by.77 of an inch.

[00:08:51]Plenty of oil on the slitting saw.

[00:10:00]>> And there we have it.

[00:10:03]You can see the slitting saw has leave nice finish.

[00:10:08]Much to my annoyance, the 0.8 mm slitting saw didn't give a big enough gap for the two cotters to close up tightly and grip the shaft.

[00:10:18]So, I'm going to have to mill another 0.4 mm off each cotter pin.

[00:10:24]Mildly annoying, and I'll remember to use a thicker slitting saw next time.

[00:10:46]All right. Now, I just need to repeat that on the second one, which I won't bother filming.

[00:10:51]Last job on the cotters for now is to drill and ream out this hole to 8 mm.

[00:10:58]This cotter is the one that's going to be glued onto the shaft, so that needs to be a reamed hole. So, we got nice fit. Uh the other cotter will be a sliding fit, so I'll just drill that to a slight clearance hole.

[00:12:21]>> And finally, go in with the 8 mm reamer.

[00:12:41]The last stage here is to lock tight this cotter pin onto the shaft.

[00:12:46]I've got a bit of medium strength Loctite.

[00:13:15]And now we'll just leave that to cure.

[00:13:19]Next part is this little clamp.

[00:13:31]>> From the drawing you can see there's two half-inch holes at 90° to each other.

[00:13:37]Two 5-mil holes, again all at 90° to each other.

[00:13:44]There's a step milled here uh because the bolt has a round head with one side milled off it stop it turning.

[00:13:56]Uh there's a slot cut through here so that the bolt can clamp onto the bar.

[00:14:04]We've also got these chamfers which are purely decorative.

[00:14:09]I've got a bit of 3/4-in bar.

[00:14:12]I've already milled it to length and I've taken a few thou off each of the faces because I want to sand out the machining marks and give it a polish.

[00:14:27]And it's a pain in the neck trying to polish through the mill scale.

[00:14:31]It's much easier to take a light skim off and then polish a machine surface.

[00:14:40]That's the block set in the milling vice on parallels and I've got a vice stop and because the holes are all the same length from each end so I can just turn it round. I don't have to re-index things.

[00:14:56]So the first hole is 5-mm hole 3/16 in from this end.

[00:15:23]Incidentally, this drill is a good quality one. Came from Cartwell and it cuts so much better than all the cheap import drills I've got.

[00:15:36]I think it was two or three pounds, so not cheap but not going to break the bank.

[00:15:41]But, well worth spending money on good cutting tools.

[00:15:45]It really makes a difference.

[00:16:33]Now, I can just turn that round, make sure I've turned it through 90° and because the table's all locked, that hole's already in exactly the right place.

[00:16:45]However, don't forget to deburr the holes, otherwise the burrs will throw your part off.

[00:17:10]As if by magic, the second hole appears.

[00:17:16]All right, now we can it out.

[00:17:19]Deeper the holes.

[00:17:21]Turn it around 90°.

[00:17:34]And I'm ready to drill the 1/2 in hole.

[00:17:38]Now the 1/2 in hole needs to be 5/8 in from the end.

[00:18:08]I'm going to pull the parallels out of the way for the last two cuts as the drill is getting perilously close.

[00:18:16]The last drill is a 64th under a 1/2 in.

[00:18:30]Finally, we go in with a 1/2 in reamer.

[00:18:45]All right, nice 1/2 in hole.

[00:18:48]Now the other one is more of the same.

[00:18:50]I'll do that off camera.

[00:18:54]Okay, the last operation this setup is to mill these recesses.

[00:19:00]Now the drawing say to go down 3/32.

[00:19:04]However, I'm only going to go down a 16th.

[00:19:10]So the reason being I can adjust the height of this to adjust the position where the ball handles tighten up.

[00:19:17]So, if necessary, I can mill the recess a little bit deeper um to get the ball handle to rotate a little bit further.

[00:19:27]I've put a bit of blue Sharpie on here to make sure I get the right face to mill off cuz it needs to be that one and that one.

[00:19:38]Not that one and that one.

[00:20:03]That's come up nicely. The recess has come just past the hole, which is what I was aiming for.

[00:20:12]So, quick deburr, that's finished. I'll do the other one off camera cuz it's more of the same, and that's it for this setup.

[00:20:20]Uh next task is to machine these chamfers.

[00:20:27]The drawing say to machine them all by a quarter of an inch, >> [snorts] >> but I think that's a bit too much, so I'm going to take them down 0.1875.

[00:20:41]If it proves to be too little, then I can take more off. If I've taken too much off, then it's harder to put it back.

[00:20:48]Now, I've got a nice little shop-made angle plate to help me machine this.

[00:20:53]It's made of 1/4-in gauge plate, and it's got a zero hole there.

[00:20:59]These holes are various different angles, [snorts] 45, 40, 35, so on.

[00:21:07]And these three holes are just convenient holes for end stops.

[00:21:15]So that will go in the vise like that.

[00:21:20]That's 0.45 and that's an end stop.

[00:21:25]With that in the vise, then I can just machine the top off here.

[00:21:32]And because it's all repeatable, all I need to do, turn that over and I can go down to the same height on the DRO.

[00:21:43]The shop made tool is just a bit of gauge plate with eighth holes drilled in it.

[00:21:50]And three 1/8 silver steel pins. It was inspired by a YouTuber made something similar. Um I forget his name, Jim's workshop.

[00:22:03]Anyway, I'll leave a link in the description.

[00:22:06]His was a little bit more complicated.

[00:22:09]I changed the size to suit my vise. I've made it a bit thinner and a bit simpler.

[00:22:17]Basically, Jim had this set duplicated, whereas I couldn't see any point in duplicating them because if you want to build the other angle, you just do that.

[00:22:33]It's in the vise now.

[00:22:35]I shall slowly bring the cutter down to it just starts to cut.

[00:22:39]Zero the DRO and carry on cutting until I get to a depth of 0.1875 in.

[00:23:25]>> The chamfer stopped there at 0.180 in.

[00:23:28]Uh that looks about right to me.

[00:23:31]It's only cosmetic, so as long as it looks right, it is right.

[00:23:37]I'll do the remaining three corners off camera because that's just more of the same.

[00:23:42]And I'll show you the finished results.

[00:23:45]All right, here's the finished clamp all bar the slitting saw cuts.

[00:23:51]Um two reasons I haven't done them yet.

[00:23:54]The first is I haven't got a 1.6 mm slitting saw.

[00:23:58]And the second is that I want to polish it up first.

[00:24:05]And I don't want the polishing mop to get caught in the slot.

[00:24:13]I'm quite happy with that.

[00:24:15]I think the chamfers came out just the right depth.

[00:24:20]I've got my slitting saw now, nice 1.5 mm slitting saw.

[00:24:26]Now, I've wrapped the block in some masking tape so I don't mark the surface.

[00:24:33]That should be fine cuz it's on flats of drawers.

[00:24:38]Now, I just touched off.

[00:24:45]I'll just touch the saw on the bottom with the feeler gauge between them to get the bottom and zero the DRO.

[00:25:11]>> And we do the same on the top.

[00:25:14]Just wind it down till it drags.

[00:25:24]That's nice.

[00:25:26]And use the half function.

[00:25:36]Now just wind the saw down to zero.

[00:25:46]Lock the gib.

[00:25:49]Splash of oil.

[00:25:53]Saw a nice slow speed. And then just slowly wind in and take the cut all in one cut.

[00:26:01]Slitting saws seem to be quite happy taking a single pass cut.

[00:26:40]And that should be that.

[00:26:48]Looks like it's gone through nicely.

[00:26:51]Now I'll do the other one off camera.

[00:26:54]Of course, cuz the dimensions are all identical.

[00:26:58]Don't need to measure anything. I can just flip it round on the parallels.

[00:27:04]Tighten up the vice, and we're good to go.

[00:27:10]And here's the finished bracket.

[00:27:15]Slits came out nicely.

[00:27:18]They look nice in the central in the hole.

[00:27:24]I didn't mark up the finish when I put it in the vice.

[00:27:30]So, that's another piece finished.

[00:27:39]There's the collar, the sport bar, and the bracket all nicely installed.

[00:27:47]There's just an ordinary nut here. It's temporary measure until I make the ball handles.

[00:27:54]I've made these bolts for the bracket.

[00:27:57]I didn't video them cuz they're just very straightforward.

[00:28:01]Again, just ordinary M5 nuts as a temporary measure until the ball handles are done.

[00:28:09]It's coming on. It's nice to see some visible progress.

[00:28:14]That's it for this video. I hope you enjoyed it.

[00:28:18]Uh it's nice nothing too taxing this time.

[00:28:22]It's nice to have something that's a little bit more not having to think too much about it.

[00:28:28]Anyway, the next video is going to be a bit more involved. That'll be the first casting for the wheel head.

[00:28:35]And things get a little bit more interesting.

[00:28:39]Thanks for watching. If you enjoyed the video, please like and subscribe.

[00:28:44]If If have any comments, leave them below.

[00:28:47]I read them all and I answer nearly all of them.

[00:28:50]Thank you. See you soon.