Pyramid Challenge

[jschmidling]

I have a cast aluminum, quadrilateral pyramid that I clamped in the vice, base as cast, down and faced off the top.

Now I want to face off the bottom parallel to the top but clamping it in the vise won't work as it just slides up as the vice is tightened, or it cocks it into some random unstable position..
.






Any ideas?

Jack

 

[benmychree]

A German guy that I knew would have said "you don't can do that".

 

[Latinrascalrg1]

A block of wood with a square hole for a tight press fit that could be clamped into the vise and with the addition of a bed clamp that can be moved should give you a stable work piece, maybe! Or just clamp it directly to the bed with a few clamps?

 

[JimDawson]

Can you put a couple of screw holes in it? I would screw the faced off side to a plate.

 

[tghsmith]

if your final height allows, mill a notch across 2 of the top edges to make surfaces that can be held by the vice,,

 

[coherent]

I would secure it on its side (flats between vice jaws) and then machine the bottom from the side with light passes, rotate and complete the other half of the bottom. Since the top is surfaced, use aluminum or brass wire on the bottom (now on the side in the vice) when you secure it in the vice so the bottom can be secured/machined parallel to the already surfaced top face. Sorry if that sounds confusing, but I know what I mean..lol.

 

[RJSakowski]

I have a cast aluminum, quadrilateral pyramid that I clamped in the vice, base as cast, down and faced off the top.

Now I want to face off the bottom parallel to the top but clamping it in the vise won't work as it just slides up as the vice is tightened, or it cocks it into some random unstable position..
.



View attachment 302035


Any ideas?

Jack

Place sacrificial aluminum spacers between the part and the vise jaws and lower the part.. The spacers will allow you to face below the top of the vise jaws.

 

[Cadillac]

I would use the table and use holdown clamps on both sides. They would wedge the part between the clamps so it couldn’t move. Or hold it on the flats so it’s vertical and use the length of the endmill so your using the side of end mill.

 

[whitmore]

A block of wood with a square hole for a tight press fit ...Or just clamp it directly to the bed with a few clamps?

I'm not sure about the 'tight' fit, but you can always bed an irregular object in a bit of plaster of paris.

You have a perfectly good flat workpiece surface, and a table that it can be held against, and the vise is not helping.

 

[jschmidling]

Place sacrificial aluminum spacers between the part and the vise jaws and lower the part.. The spacers will allow you to face below the top of the vise jaws.

You win! Worked great.




Wood and plastic occurred to meas the right approach but the wrong stuff. Never thought of aluminum.

Thanks for all the ideas.

Jack