[ImanCarrot]

Having seen other posts about making a Turner's Cube on here, I've got a few spare days and am gonna make one from acrylic (should be nice n polished, I'm diamond machining it).

My question is: which depth should the first circle be please. eg: if the cube is 50mm on each side, is there a formula to tell me what depth I should cut the first circle at? I reckon it would be a function/ fraction of the overall width of the starting cube, say about 75%????. I want to cut each of the faces' circles (picture a dice numbered face 1-6) at the same depth so that it's automated.

Any ideas gratefully received. Many thanks in advance.

[Geof]

Don't be a lazy git. (I hope being British in origin I can be nasty to a fellow ex-countryman )

Make cross-sectional sketch and figure it out yourself.

[Oldmanandhistoy]

Don't be a lazy git. (I hope being British in origin I can be nasty to a fellow ex-countryman )

Make cross-sectional sketch and figure it out yourself.

(wedge)

[Geof]

I just went back and reread the title. No I cannot help with a cirlcle

But I have to be nice and say I will be interested in seeing how it looks if it is turned optically smooth on all surfaces. It should look fantastic suspended in a window with the sun shining through.

[stevehuckss396]

My question is: which depth should the first circle be please. eg: if the cube is 50mm on each side, is there a formula to tell me what depth I should cut the first circle at?

I have a crude Excel spread sheet that will size the circle and depth up to 10 steps.

for a 50mm cube it would look like this...

Cube Size	Bore Size	Bore Depth	Edge Thickness
50.0000	42.5000	7.5000	3.7500
35.0000	29.7500	5.2500	2.6250
24.5000	20.8250	3.6750	1.8375
17.1500	14.5775	2.5725	1.2863
12.0050	10.2043	1.8008	0.9004
8.4035	7.1430	1.2605	0.6303
5.8825	5.0001	0.8824	0.4412
4.1177	3.5001	0.6177	0.3088
2.8824	2.4500	0.4324	0.2162
2.0177	1.7150	0.3027	0.1513

Looks like you could go 5 steps depending on the size of your tooling.

[ImanCarrot]

Aha! many thanks all, I got the tooling made and have cut out the acrylic blank then, just when I was figuring out how to hold the bugger we got a rush job for some other components that we make (100K's worth) so it'll have to go on the back burner for now. *sigh* I'm deterined to make it though! it should as Geof says, look well nice when done

[Oldmanandhistoy]

look well nice when done

Look forward to it

John

[wjfiles]

This any help

[ImanCarrot]

Thanks, all is a bit clearer now- the depth of the circle in jw's seems to be a factor of 6.3 to 6.7 of the circle diameter, whilst steve's is exactly a factor of 5.667 that of the diameter.

I've looked into it and the diameter of the circle seems to about 75% (as i thought) of the long axis of the cube machined (across the diagonals) since the diagonals are governed by the size of the internal cube and this will be exactly the size of the previous larger cube minus this value divided by two all seems pretty straight forward.

Now... will my vacuum chuck hold it and how to centre it hehe. I'll get there!

Iain

[neilw20]

If it was 70.7106781 per cent I think it would fall apart?
Does that number look familiar, or was it 85% which is close too 0.866.
One or the other (LOL) you figure it!

[stevehuckss396]

If it was 70.7106781 per cent I think it would fall apart?
Does that number look familiar, or was it 85% which is close too 0.866.
One or the other (LOL) you figure it!

Neil is exactly correct. The numbers in Excel were that the bore was 85% of the cube and the depth was 15% if the cubes size. The next cube would be the size of the cube minus ( bore depth times two). And then it all starts over again. I played around with the percentages and this is what i found would look good to me and give as many steps as possible. I thought i might try going 7 steps on a 3 inch cube.

I think i might try this one someday. This is more of a millers cube. And i might try making a hybrid cube with circles and squares. It's different than anything i have seen before.

Is it healthy to put this much thought into a 3 inch cube of aluminum?

Steve

[NateTG]

On a CNC mill you could try packing alternating cubes and octahedrons - which can be caged inside each other rather than being connected by webbing, although you'd probably end up needing to use some very small tools.

[ImanCarrot]

Muahaha I made one- couldn't do it on the Diamond Turning lathe so it's not as polished as I'd wanted, but the maths works out ok!

See here and thanks too all for the advice. it sure looks pretty

http://www.cnczone.com/forums/showthread.php?t=57336

[davek]

Sorry to resurrect the necro thread. Normally I wouldn't be caught dead with a necrophiliac.

Do the cubes using the 85% circle, 15% depth ratio need any special support doing the final face if milled in a vise? I made a ball in a box once. It took me a huge amount of time and an elaborate setup on the final face.

I used to be able to do more personal work but machine time is at a premium right now and I can't come in early to do personal work. I would like to figure out a turner's cube I can mill quick and dirty at lunch over a couple days that would still look neat. Three boxes would be plenty. That way I could make a few also.

How do you figure circle size for best appearance if you want to call the depths yourself? Say, I wanna go 1/4" increments? I've played with it in draftsight a bit and don't know if I should try for somewhat uniform gaps or somewhat uniform contact webs. Making it work is not a biggie but I don't really have the machine time to figure what looks best by trial and error.

If the 85% - 15% deal machines well with no plug making or special fixturing then "if it ain't broke don't fix it". Otherwise it's to the drawing board for a stouter part.

I want to do it right the first time with little machine time but computer time at home is more available. I only have draftsight as a cad program and excel to play with.

[davek]

The thing I was looking at besides this thread to try to figure dimensions for a cube was the CNC cookbook web site.

CNC Cookbook: Turner's Cubes

I was trying to figure the ratios used in their calculator as the narrator on this page says he did. I finally loaded their demo and added some more stuff to my already groaning registry and got a surprise.

The pic on the website of a sample 4" cube calculated did not match the screen I got in the demo.

The website had even .5" depths which would match the next cube size. .5" deep on a 4" cube to make a 3" cube for example. The actual demo has different depths which then don't exactly match the next cube called out. It also has a "percentage overlap" callout. The cube which was made in later on the page didn't seem quite right in the numbers either with the first depth being .5" and the rest being .25".

Now I've got some new info to chew on and try to come up with a good multiplier next time I have time, probably next weekend. Still, this is pretty frustrating.

[davek]

here