I've been wanting a carriage stop for the lathe for a while. Now that I have a milling machine, making one becomes a reasonable proposal. After measuring up the lathe way I did a quick design that would utilize an offcut of the square bar I used to make the V-blocks, and subsequently used to try out my fly cutter. https://pic8.co/sh/H0kGt1.jpg
A chunk of the square bar was cut off on the band saw. Since the stock is now getting short, I'm using a bit of all-thread and some hold down nuts as a screw jack to hold the jaws parallel. https://pic8.co/sh/vVO2Er.jpg
The 'ends' of the stock were milled flat with the fly cutter. Having turned my insert to a new point, the surface finish was really nice. https://pic8.co/sh/zH0lJS.jpg
Plans were printed out with some key dimensions: https://pic8.co/sh/vDS1QQ.jpg
The main form of the body was created by milling out a corner, then positioning it in the vise at a 45 degree angle and using an end mill to carefully mill out the inverted V. The meeting of the obtuse angle was determined by eye and feel (running my finger nail over the joint to feel for a 'lip', then taking a tiny cut (0.01mm) until the lip was gone. https://pic8.co/sh/h8gMCM.jpg https://pic8.co/sh/iBUvtx.jpg
That went pretty well actually. https://pic8.co/sh/u5ErJx.jpg
The required side holes were drilled and reamed/tapped as necessary. The biggest tap I had that was suitable was an M14x1.5, so I designed around this. Ideally, I would use a 1mm thread pitch, so 1 turn of the stop would be 1mm of travel, but that's not essential really. Once I get an accurate way of dividing a circle on the mill (or a Hex collet block), I could put 3 lever holes in the bolt to allow for accurate 1/3 turn (0.5mm) adjustments if I want.
The holes were positioned using two DRO datums (one on the ABS scale, the other on the INC scale) with the origin of these two co-ordinate systems being set as per my scribbles. https://pic8.co/sh/zuTdI6.jpg https://pic8.co/sh/8UqeME.jpg https://pic8.co/sh/bjkAbu.jpg
The next step was drilling the top holes, one for the indicator clamping screw and a through hole for the body clamp screw. The body was held in the vise and the counterbored hole drilled for the clamping screws. Positioning the indicator clamping screw was achieved by indicating on the shank of an 8mm drill inserted into the reamed hole. This allowed me to position the hole so that it would miss the reamed hole by 1mm. Again, both DRO co-ordinate systems were used, one to position the indicator clamp hole, the other to position the body clamp hole. Having two co-ordinate systems is very useful. https://pic8.co/sh/UUwCM5.jpg https://pic8.co/sh/hciqG4.jpg
The indicator clamp hole was drilled out to 3.5mm, with a 4mm clearance hole down to the center line of the cross hole and an 8mm (I think) counterbore for the head. Bit of trivia, for metric socket head bolts, the depth of the counter bore is the diameter of the bolt, i.e. an M4 bolt needs a 4mm counterbore, and an M10 bolt would need a 10mm counterbore, that makes it easy to remember. https://pic8.co/sh/cJUQZU.jpg
After the hole was tapped, I put the piece back in the band saw, this time to cut the clamping slot. Since I don't yet have any slitting saws (one more thing to get). Watching the cut carefully, I was able to catch it as it emerged into the indicator hole, without having the blade fall on the other side. I had to improvise a little with work holding (making small part holding plates for the bandsaw is yet another job to do). I could have done this with a hacksaw, but the band saw is much more precise. https://pic8.co/sh/D3BXfH.jpg
Fuckit! That's not quite right. Turns out I got myself disoriented when figuring out where to drill the hole, and drilled it on the wrong side. https://pic8.co/sh/2bOOIH.jpg
Well, that was recoverable, but not without leaving a scar. I re-drilled the indicator clamp hole, this time in M5 because the hardware store didn't have the bolt I wanted in M4. I don't think I took any photos of that, because I was pissed. This was only the start of my problems though.
The design I made called for a scallop to be cut in one side to accommodate part of the indicator body. This was required so that the indicator stem would go all the way through the clamp. This was partly why I made the smaller fly cutter. The plan was to use that as an improvised boring bar and nibble out the scallop. The first step was to set the diameter. To do this I threw a scrap of wood in the vise and cut a shallow circle at the approximate diameter (just under). After measuring the hole that was cut, I could calculate the required change in diameter to get to my desired diameter. Using the indicator, I could move the cutter by half of the required change in diameter. https://pic8.co/sh/vvYbXf.jpg
Well, the cut didn't go to plan very well. It was a deeply interrupted cut and I have basically zero experience using HSS fly cutters, so my tool geometry was probably off. Anyway, the first thing that it did was chip off the corner of the tool, then it burned off the corner after I re-sharpened it, this went on for a while with me getting increasingly frustrated. Don't mill when you're frustrated! Eventually, I gave up on the round scallop and decided to just mill out a pocket that would give clearance. I stuck a 12mm end mill in and started to clean up the mess. Being frustrated, I was going too fast and making a climb cut (cutting with the rotation of the tool) into an interrupted cut. Needless to say, things didn't go well. The end mill dug in, pulled the piece out of the vise and chipped off one of the cutting edges (which hit me in the guts, but not too hard). Don't mill when you're frustrated! https://pic8.co/sh/iYFoQV.jpg
After walking away and cooling off, I returned and used a 20mm end mill to conventionally (against the rotation of the cutter) mill away the clearance. I also made the bottom strap, which was a very simple piece of 25x10mm bar with a hole tapped in the correct location.
Now it was on to making the stop bolt. This was made from some 22mm bar I found. Since I don't have an M14x1.5 die, I had to single point the thread. This also results in a much straighter thread. https://pic8.co/sh/3nwgNU.jpg
A length of the shaft was turned down to 20.7mm (a diameter that would give a circumference that was a whole number of mm (65mm in this case) so that the knurl had a good chance of aligning) then knurled. The bolt section was then parted off and the locking nut was drilled and tapped. https://pic8.co/sh/c24rYQ.jpg
The bolt was put back in a 5C collet to face the end. https://pic8.co/sh/DAhwN3.jpg
The last step was to mill about 0.5mm off the bottom of the main part, leaving a ledge about 2mm wide as a fulcrum point for the locking plate. Without this material taken off, the assembly was a close sliding fit on the lathe way. Milling off 0.5mm allows the locking plate to be pulled tight against the underside of the lathe way.
All the parts are now ready for assembly. https://pic8.co/sh/lo6uOd.jpg
Putting it together is very simple. The reamed 8mm hole is a close fit on the indicator shaft and the locking screw holds it firmly, everything is very rigid. This piece has some scars from my various fuckups, but that's just an ever present reminder for me to not fuck up in that way next time. I'll likely fuck up in a different way. Very happy with the finish that the fly cutter made, particularly with a fresh insert. It looks pretty good, but feels even better. https://pic8.co/sh/FaPHw8.jpg
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