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I find it hard to believe that someone would want to make brake rotors smaller. 1/4" is a huge difference, 1/2" I'll bet those things burn up and warp quickly. What's his reasoning?
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POTD- PROJECT OF THE DAY: What Did You Make In Your Shop Today?
- Thread starter wachuko
- Start date
- Joined
- Dec 18, 2022
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- 2,634
I haven't opened my gap yet but the rest looks familiar. I was thinking about fabbing a special tool holder that would extend my reach when configured as you are..... hummmm
- Joined
- Sep 2, 2013
- Messages
- 5,418
Possibly a newer larger diameter rotor cut down to fit in an older smaller diameter wheel to end up with the largest possible diameter for that wheel. Mike
- Joined
- Apr 15, 2014
- Messages
- 27
I *think* he said they were going on the rear and he is reusing calipers and wheels he already has. I'll quiz him again when he picks them up tomorrow afternoon. He is a lifetime car guy and autocrosser and I think he knows what he is doing.
I decided on sort of a whim to pull my old reflecting telescope out of storage and take a look up at the sky. My old telescope was new when I bought it from Texas Nautical Repair in Houston in maybe 1986--it's a Meade 8800 Newtonian reflector that was mounted on an equatorial mount. The mount is decent but was intended for smaller and lighter telescopes, and with the 8"-aperture mirror telescope wiggles a lot from every influence. So I am remounting that telescope into an altitude-azimuth mount that avoids all the mechanical complexity and cantilevered design.
And then I needed to revise the old mount to accept a 4" refracting telescope that is far more compact and appropriate for that mount.
The mount itself is a Japanese Mizar AR-1, rebadged by Meade Instruments, and is probably a little beefier than the Super Polaris mount made by Mizar's competition in Japan, Vixen, for Celestron. Got that? There will be a test.
Both aspired to be stiff enough for the scopes those companies really wanted to sell--their compact Schmidt-Cassegrain catadioptric telescopes.
Here's my old Meade in service last week:
Notice the three counterweights on the shaft opposite the telescope. Each of those is 4 Kg, or about 27 pounds for all three. A portable metal structure with 30 pounds on one side counterbalancing the load on the other side is going to be wiggly. Plus, a Newtonian reflector puts the eyepiece on the side of the end of the tube that points up, so the tube needs to be lower than the eye for the most part. I'm constantly tripping over the legs of that tripod.
Here is the same mount and tripod with its new load:
Notice that not only is the refractor package much smaller, but it counterbalances on the equatorial mount using just one of those three counterweights. And one looks through a refractor at the low end, instead of standing next to the telescope in use. The feet stay away from the tripod legs. To make this work, I needed to mount a clamp for the dovetail rail that telescopes now use to allow interchangeability. The clamp fit on the original plate pretty well, but the clamp moveable jaws interfered with the lip on that old plate. So, I milled that lip down a bit to provide clearance. The plate is white metal so no need for a real mill, which is good since I don't have one. I just chucked up an end mill in the Delta drill press (that has a Jacobs chuck that locks to the taper using a threaded collar) and used my flimsy old X-Y table. It worked well enough.
But the real fun was making the altitude bearings for the sides of the Meade reflector tube. Back in the day, Newtonian reflectors mounted in a Dobsonian mount were home-made affairs, often put together with minimal carpentry skills, sonotube, and cheap plywood. But I have this nice, commercial-looking telescope and wanted something a bit more polished, so to speak. Here's the design:
Those big round disks on the sides are the altitude bearings. They ride on a couple of Teflon pads each, which with smoothly machined aluminum provides just the right friction to keep the balance scope where you put it but with very little stiction. Tracking an object in view at high power requires lots of little nudges as the Earth rotates under the sky, and these need to be smooth with no backlash.
I bought a couple of thin cut-offs from large round stock of 6061--one was 11-3/4" in diameter x 1-1/2" thick, and the other was 8-1/4" in diameter and the same thickness. Both were sawcut at a skew of at least a quarter inch. Machining them into nice-looking disks required first chucking them up by the rim to face one side and clean that up, then turning it over to face the other side, using the jaws of the chuck as the reference surface. That was good enough--the two faces ended up within a thou of parallel which is much better than needed.
But then I needed a way to turn the rim, so I needed to mount it by the middle. I grabbed a piece of 1-3/4" CRS round stock that I had in the pile to make an arbor for holding the disk by the center. I used my newly aligned replacement tailstock to drill holes up to 7/8", and then bored it out to an accurate 1" bore. Then, I turned that steel down to provide a 1" shouldered mount and drilled and threaded a hole in the end for a clamp bolt. I hit these dimensions within about half a thou for just a bit of clearance.
Here's the first facing operation on the bigger disk:
Here's the support arbor I made:
Turning the rim after mounting on the arbor and bumping it in on the 10" Skinner 4-jaw chuck:
The two finished altitude bearings, each 1.315" thick and 8.000" and 11.500" in diameter. No, there's no reason one needed to be bigger than the other--I was just saving the tools and one blank was bigger than the other--but if it looks good people will think there must be a reason
Then I needed to drill and counterbore mounting holes for attaching the factory tube rings to the disks. The screws were metric and my set of counterbore drills are SAE and just the wrong size for the M5 metric socket-head screws. So, I drilled the holes and then counterbored by plunging an end mill. Aluminum is sort-of fun to work with and I can get away with stuff that just wouldn't work with hard materials.
I spent a lot of time at the surface plate trying to get everything aligned, which isn't as easy as it seems like it ought to be.
And here are the finished disks mounted to the factory tube rings, with the telescope mounted in the rings. Balance is perfect
I have purchased the baltic birch furniture-grade plywood for the base, and found a lazy susan bearing that is much higher-end than I would have expected.
If the amateur telescope making parts suppliers figure out that Woodcraft sells such a nice azimuth bearing, we'll see them again on their websites for a hundred bucks.
I still need to do the carpentry, but that's cellulose machining and I won't bore you guys with that.
Rick "instead, boring you with this" Denney
And then I needed to revise the old mount to accept a 4" refracting telescope that is far more compact and appropriate for that mount.
The mount itself is a Japanese Mizar AR-1, rebadged by Meade Instruments, and is probably a little beefier than the Super Polaris mount made by Mizar's competition in Japan, Vixen, for Celestron. Got that? There will be a test.
Both aspired to be stiff enough for the scopes those companies really wanted to sell--their compact Schmidt-Cassegrain catadioptric telescopes.Here's my old Meade in service last week:
Notice the three counterweights on the shaft opposite the telescope. Each of those is 4 Kg, or about 27 pounds for all three. A portable metal structure with 30 pounds on one side counterbalancing the load on the other side is going to be wiggly. Plus, a Newtonian reflector puts the eyepiece on the side of the end of the tube that points up, so the tube needs to be lower than the eye for the most part. I'm constantly tripping over the legs of that tripod.
Here is the same mount and tripod with its new load:
Notice that not only is the refractor package much smaller, but it counterbalances on the equatorial mount using just one of those three counterweights. And one looks through a refractor at the low end, instead of standing next to the telescope in use. The feet stay away from the tripod legs. To make this work, I needed to mount a clamp for the dovetail rail that telescopes now use to allow interchangeability. The clamp fit on the original plate pretty well, but the clamp moveable jaws interfered with the lip on that old plate. So, I milled that lip down a bit to provide clearance. The plate is white metal so no need for a real mill, which is good since I don't have one. I just chucked up an end mill in the Delta drill press (that has a Jacobs chuck that locks to the taper using a threaded collar) and used my flimsy old X-Y table. It worked well enough.
But the real fun was making the altitude bearings for the sides of the Meade reflector tube. Back in the day, Newtonian reflectors mounted in a Dobsonian mount were home-made affairs, often put together with minimal carpentry skills, sonotube, and cheap plywood. But I have this nice, commercial-looking telescope and wanted something a bit more polished, so to speak. Here's the design:
Those big round disks on the sides are the altitude bearings. They ride on a couple of Teflon pads each, which with smoothly machined aluminum provides just the right friction to keep the balance scope where you put it but with very little stiction. Tracking an object in view at high power requires lots of little nudges as the Earth rotates under the sky, and these need to be smooth with no backlash.
I bought a couple of thin cut-offs from large round stock of 6061--one was 11-3/4" in diameter x 1-1/2" thick, and the other was 8-1/4" in diameter and the same thickness. Both were sawcut at a skew of at least a quarter inch. Machining them into nice-looking disks required first chucking them up by the rim to face one side and clean that up, then turning it over to face the other side, using the jaws of the chuck as the reference surface. That was good enough--the two faces ended up within a thou of parallel which is much better than needed.
But then I needed a way to turn the rim, so I needed to mount it by the middle. I grabbed a piece of 1-3/4" CRS round stock that I had in the pile to make an arbor for holding the disk by the center. I used my newly aligned replacement tailstock to drill holes up to 7/8", and then bored it out to an accurate 1" bore. Then, I turned that steel down to provide a 1" shouldered mount and drilled and threaded a hole in the end for a clamp bolt. I hit these dimensions within about half a thou for just a bit of clearance.
Here's the first facing operation on the bigger disk:
Here's the support arbor I made:
Turning the rim after mounting on the arbor and bumping it in on the 10" Skinner 4-jaw chuck:
The two finished altitude bearings, each 1.315" thick and 8.000" and 11.500" in diameter. No, there's no reason one needed to be bigger than the other--I was just saving the tools and one blank was bigger than the other--but if it looks good people will think there must be a reason
Then I needed to drill and counterbore mounting holes for attaching the factory tube rings to the disks. The screws were metric and my set of counterbore drills are SAE and just the wrong size for the M5 metric socket-head screws. So, I drilled the holes and then counterbored by plunging an end mill. Aluminum is sort-of fun to work with and I can get away with stuff that just wouldn't work with hard materials.
I spent a lot of time at the surface plate trying to get everything aligned, which isn't as easy as it seems like it ought to be.
And here are the finished disks mounted to the factory tube rings, with the telescope mounted in the rings. Balance is perfect
I have purchased the baltic birch furniture-grade plywood for the base, and found a lazy susan bearing that is much higher-end than I would have expected.
If the amateur telescope making parts suppliers figure out that Woodcraft sells such a nice azimuth bearing, we'll see them again on their websites for a hundred bucks.
I still need to do the carpentry, but that's cellulose machining and I won't bore you guys with that.
Rick "instead, boring you with this" Denney
Last edited:
- Joined
- Oct 14, 2013
- Messages
- 1,294
Ah, those! I used one of those turntable bearings on a GIRST Robotics bot... they are a true turntable: vertical. Radial, and moment load capable. Not very much backlash either.
The 'zon has them too.
The hole pattern, however, was nibbled out by drunken beavers. Had to re-do it after taping the gap
Sent from my SM-S911U using Tapatalk
The 'zon has them too.
The hole pattern, however, was nibbled out by drunken beavers. Had to re-do it after taping the gap
Sent from my SM-S911U using Tapatalk
- Joined
- Nov 25, 2015
- Messages
- 9,775
needed some better washers for the grinder I picked up... so roughed these out.
I may make some more for all the grinders. I hate some of the stamped steel these days. My dads and my old grinders were machined. The cast ones from the garage sale were good, but there were 2 stamped as well, and they are deformed from over tightening, that's why I made these.
I may make some more for all the grinders. I hate some of the stamped steel these days. My dads and my old grinders were machined. The cast ones from the garage sale were good, but there were 2 stamped as well, and they are deformed from over tightening, that's why I made these.
