Reply with Quote35.26 degrees????
Better wait for Mr Warfield, I have more faith in him than my trigonometric ability.
Now that's a Warfield to the rescue
35.26 degrees????
Better wait for Mr Warfield, I have more faith in him than my trigonometric ability.
An open mind is a virtue...so long as all the common sense has not leaked out.
I keep getting 90º 55º 35º
Base = 4.2526, Height= 3.0, Hypotenuse = 5.1961
I'm anxious to get the cube spinning, and those sapphire bearings look really interesting!
Okay Mr Widgit. I got my cube up on end with 2 rotations. The first is a 45 degree rotation around Z. The second was not intuitive, so I'm glad I could let the CAD program figure it out. It worked like this:
Geof, congratulations, you have essentially the same angle just from a different normal as the two sum to 90 degrees. I think I read somewhere that you do all your CNC programming without CAM? You definitely have some geometry skillz to do that, my friend! I'm too dumb (or too lazy) to do all that in my head. I kept wanting to visualize 2 45 degree rotations, but that 2nd rotation just ain't 45.
Now I can do this stuff in CAD, but I can only assume what magic the Widgitmaster must use to make that happen on his mill. I'm thinking 2 sine bars or other angle blocks?
Use the first to rotate the cube 45 degrees around Z, perhaps on a fixture plate of some kind. Now use the second to kick it up 54.74 degrees and you have it.
Does that work? I know you've gone to bed in Florida, so I hope I can see the exciting conclusion in the morning. I know you'll publish a fine photograph of the fixturing/setup, and you know that photo will be appearing in the CNCCookbook.
I agree, those saphire bearings are very cool. I can't wait to see your display stand, Mr Widigt. I know it'll be a gorgeous piece of art that I will be lusting after.
BTW, I don't know if you liked the dodecahedron I showed, but I would think making each solid would also be an interesting set of projects to display. I suspect intuitively (but I have had a drink or two this evening!) that you could take your boring bar to each face of the dodecahedron and create quite an amazing Turner's Cube the likes of which has perhaps not been seen before. Dodecs within dodecs. Think what a tasty fixturing problem that would turn out to be!
But we digress. I eagerly await hearing whether this helps, or if I need to get back in my CAD program and figure something else out.
Best,
BW
PS I am finally taking my first baby steps towards converting my mill to CNC. I can't stand being able to make all these drawings and then having to bring them to reality by hand!
<edit>
dang. I was wrong.
That's what I love about Trig, you can give a problem to ten people, and get six different answersOriginally Posted by MrWild
After using my calculator, and then drawing the triangle in CAD, I came up with the same numbers, so I'll stick with them!
The good news is UPS dropped of the materials for my NEW 24x24 V-Router, so I'll be working on those parts this weekend!
The ideal is that you get the same answer six different waysThat's what I love about Trig, you can give a problem to ten people, and get six different answers....
.
The thing I find about these types of problems is that they are non-intuitive; you want to be able to tip 45 one way and then 45 another an-it-dont-work!
The way I approached this was to visualize the cube facing me.
I tilted back 45 degrees; now the corner I want at the bottom is at the lower left and the other is at the upper right.
The height of the corner at the upper right is the diagonal of one face; 3 x root 2 or 3 x 1.4142 = 4.2426
The base width, this height and the diagonal between the lower left corner and the upper right form a right-angled triangle.
I need to rotate the hypotenus of this triangle, i.e. the diagonal to an upright position, so I need to know its angle of inclination.
The tangent of the angle at the lower left corner is the length of the side opposite (4.2426) divided by the length of the side adjacent (3).
Dividng 4.2426 by 3 and taking the inverse tan (and I do use a calculator not trig tables; I am not that much of a stick-in-the-mud
An open mind is a virtue...so long as all the common sense has not leaked out.
unless i am seeing things wrong ..... i would set the block upright in a small grinding vice.... use a v block to bring an edge to the top... then mount the grinding vice in my mill vice at a 45.... i may be missing some thing tho ... i am at work and am in a bit of a hurry
dam see what i get for being in a hurry ... i get to be wrong
Last edited by Hennessy; 02-21-2008 at 03:43 PM. Reason: i was wrong
You got Geof!
I had the precision for angles setting, set to not display decimal points in AutoCAD
It now displays 54.7354°
Your numbers match mine exactly!
Holding the cube is not a big problem Bob, as one angle is 45° so I can set the cube in a V-Block, and use a sine plate for the other!
The trick will be to dial in the three surfaces to the spindle, and put a small precision hole for the pointed pins, and inserting them.
Then making the base is really easy, thats when I get to make it look fancy with polished stainless!
Widgit
Widget,
For some reason, I assumed that you would put the jewel bearings in the cube and use the pins in the base. That way, you could take the cube off the base and hand it to someone to examine without getting stuck.
Nice job.
Ken
Kenneth Lerman
55 Main Street
Newtown, CT 06470
Being fundamentally lazy (after all I am getting the WidgitMaster to make my acrylic Turner's Cube
I would get some tiny ball races, 0.5" OD .125" ID, one I would mount in the bottom of my base and at the top of the base I would have a spring loaded plunger with the other mounted in the lower end of the plunger. The corner of the cube would just sit in the bearing ID and with the spring it would be easy to lift out. If you want to stop people doing that just have the top one mount4ed in a threaded plunger and have a lock nut. This way when the cube is out of the base it still has all corners intact.
An open mind is a virtue...so long as all the common sense has not leaked out.
Widgetmaster-
How about making the cubes from Steel and Nickel plating (or magnetic stainless) them and having a rare earth magnet in the top and bottom of the frame, and letting the corners of the cube be the bearing points? Easy to remove, and you could put it back in any orientation.
Here's a great source for rare earth magnets:
www.kjmagnetics.com (no affiliation except I've bought dozens of magnets from them)
NEATman
Being an engineering student, and a pretty good one, I have a good bit of free time at school in front of the computers. I start my morning 5 days a week going to check out bob's website and widgits threads. I have to say, I have never once been disappointed. There is always something cool to see or something new to learn. They also always provide me with the motivation to go make something myself if I don't have it. Thx Bob and Eric, you start my morning off right.
P.S. Thank god your back Bob, I was going through cookbook withdrawals.
P.S.S This whole idea is awesome, and I just realized I have some aluminum and a big hunk of copper that would work great to try one.
You might want to get some opinions on machining copper before embarking on making a Turner's Cube in copper. I am possibly too pessimistic, but you may have more fun bashing your head against the nearest concrete wall; copper is a real pain to machine.
An open mind is a virtue...so long as all the common sense has not leaked out.
Not if you get the right stuff.You might want to get some opinions on machining copper before embarking on making a Turner's Cube in copper. I am possibly too pessimistic, but you may have more fun bashing your head against the nearest concrete wall; copper is a real pain to machine.
Every now and then we make some EDM electrodes out of tellurium copper alloy 145 (99.5% copper, 0.5% tellurium, 0.01% phosphorus). The stuff is very easy to cut, have even put a slab on a surface grinder to get a nice flat reference surface, with no problems.
Not everyone can afford a nice Grinding Vise big enough to hold a 3" cube!unless i am seeing things wrong ..... i would set the block upright in a small grinding vice.... use a v block to bring an edge to the top... then mount the grinding vice in my mill vice at a 45.... i may be missing some thing tho ... i am at work and am in a bit of a hurry
dam see what i get for being in a hurry ... i get to be wrong
With all the tools and machinery I own, even I don't have one!
So off to the V-Block and Sine plate it is!
Widgit
www.widgitmaster.com
It's not what you take away, it's what you are left with that counts!
Two Turner's Cubes made from 303-SS
Widgit
ya it was one of those things i really needed for one job. used it on a few things but it just sits in the cabinet most of the time.... not exactly a tool u need to have in a shop but its nice.
looking at your setup i feal like i cheated... i made mine on a vf2.
whin i get home i will see if i can find the pix of mine. i made one part run with circles and one with ellipses.
Hennessy
A little disappointed, but the project must go on!
Those little sapphire vee-jeweled bearings I had ordered arrived yesterday, and they are too delicate to support the massive weight of the stainless steel cube (1lb 5.4oz) I would estimate a SS cube of 1"x1"x1" would be the limit for something so delicate.
So as an alternative solution to keep the cube spinning, I have ordered 4 small double sealed bearings. To use them I need to make some little posts to fit into the bearings, and press into the points of the cube!
The bearings have an OD of .250" dia, an ID of .125" dia, and a height of .1094" Here are some sketches of what I had in mind
Widgit
Last edited by widgitmaster; 02-23-2008 at 08:02 AM. Reason: typo
Read my suggestion a few posts up, I don't think you need to do anything; just put the corner in the bearing.
An open mind is a virtue...so long as all the common sense has not leaked out.
