View Full Version : What is this fixture for??

12-14-2003, 09:02 PM
The heavy part is made of 1" thick aluminum plate. The other pieces are from 1/4" angle and flat stock.

The long bolts fit into the threaded holes on either side of the round part.


12-14-2003, 09:48 PM
Obviously, it's for making a watchimacallit. I have several of those.

12-14-2003, 10:15 PM
It appears able to hold an integrated cylinder/head combo for valve hole machining.

Shed Machinist
12-14-2003, 10:17 PM
If you look very closely it looks like what they used in 27498968 b.c. where you hooked it up to the back wheel of a 1956 dodge viper to send people forward in time to intercept secret messages during world war negative 3.

Just Joking, sorry couldn't resist.

12-14-2003, 10:54 PM
Darryl is probably right. I picked up a number of shop-made fixtures at an auction. Some I may use, others I'm saving for the metal. If it was cut, bent, formed, milled or welded, there's probably a tool somewhere to hold it.

It's a side of resourcefulness that few people get to see. I've seen some amazing pieces of art generated just to hold a tool or metal stock for machining.

12-15-2003, 12:16 AM
Shed is right and I want in on the ground floor,it is obviously for a time machine,maybe you should look for the rest of the parts put them all together and see if anybody comes out http://bbs.homeshopmachinist.net//biggrin.gif

12-15-2003, 01:48 AM
It is obviously a male chastity device.

Or a fixture of some kind... http://bbs.homeshopmachinist.net//biggrin.gif

12-15-2003, 02:08 AM
Here's what I used it to make:



It's an aluminum dodecahedron. The fixture is mounted in the three-jaw for turning the dodecahedron. You only have to turn ten of the twelve faces on the fixture. It took about two hours taking light (0.01") cuts.


When it's spinning, it looks like something out of a '60s sci-fi film.


[This message has been edited by winchman (edited 12-15-2003).]

12-15-2003, 05:22 AM
Wow, it IS a time machine!

Forrest Addy
12-15-2003, 06:04 AM
NICE piece of work. This from a guy who's made hundreds of prooduction fixtures over the years in a hard and competitive environment where I seen 'em all.

It bears all the marks of good fixture design: rigidity, simplicity, solid referencing, good tooling acccess, repeatable opeation, and economy of construction.

You done good, winchman.

My buring question is how do you index the part for subsequent facets?

12-15-2003, 09:04 AM
Thank you, Forrest.

You only need to mark one end of the blank with scribes every 72* on the tapered section. These are lined up with a mark on the round part of the fixture as the faces on the other end are cut. The vertices between the first five faces serve as alignment marks for turning the faces on the other end.

I used a CAD program to figure the angles and the dimensions of the blank. Getting the blank proportions correct is important. I cut the first tapered end, made the fixture cup to fit it, then cut the other end to fit the cup. The vertices between the first five faces fit the cup snugly.

The first face is cut until the flat area just touches the edge of the taper on the other end:


The carriage stop is then set for making the rest of the cuts.


Michael Az
12-15-2003, 01:42 PM
Very nice.

12-16-2003, 01:30 AM
Roger, if you knowed what to use it for, whatchu askin us for???

12-16-2003, 01:59 AM
Showoff!! http://bbs.homeshopmachinist.net//biggrin.gif

12-16-2003, 03:21 AM
It's a test. http://bbs.homeshopmachinist.net//smile.gif And, BTW, I want to see an icosahedron please...

[This message has been edited by Evan (edited 12-16-2003).]

12-16-2003, 03:37 AM
Very nice indeed. Now that you have shown off, you had better write up how to do it for Neil for those of us that are not blessed with your devine insight into cubic solids so we can play too damn it! http://bbs.homeshopmachinist.net//biggrin.gif

12-16-2003, 04:25 AM
Evan started an interesting thread a while back about machining the platonic solids.

That was the inspiration for the aluminum hexasphericon and for this project.

I thought Evan (or someone else) just might recognize the angle on the fixture as the 116.5* angle between the adjacent faces of a dodecahedron.

Actually, I think a similar fixture with the cup set at different angle would work for turning an icosahedron. Indexing would still be every 72*, but you'd have to move the piece around more to get all the faces done.


I can feel my brain turning to mush.


12-16-2003, 11:05 AM
I'm with Thrud: this is just begging to be a magazine article.

12-17-2003, 03:14 AM
<font face="Verdana, Arial" size="2">Originally posted by SGW:
I'm with Thrud: this is just begging to be a magazine article.</font>

Yeah, don't make me drive down there and find you... http://bbs.homeshopmachinist.net//biggrin.gif

12-17-2003, 04:21 AM
Thanks for the encouragement. I'm going to buy a copy of the magazine so I can see what's involved in submitting an article.

Right now I'm getting ready to make a wooden icosahedron so I can get a better idea of how to machine one. Here's the wooden dodecahedron I made. I guess I can post it here since I made the parts on the milling machine using the rotary table.

The triangles for the icosahedron will be easier to make than the pentagons. I hope.


[This message has been edited by winchman (edited 12-17-2003).]