How to mill a flip...accurately??

[carguy327]

Hello Zoners,

I'm milling a larger decorative piece that should really be milled with a 5-axis machine. Like I can afford one of those. So I figure it'll need to be milled from different sides. As this object is purely decorative,it doesn't need to be very accurate...0.05 out..maybe

I've seen guys milling on machine centers and they flip an object either 90 or 180 degrees. perfect everytime. How is this done ? ....semi accurately. My backgroud is of a digital modeller, so my CNC knowhow is a bit limited.

I'm milling 15lb HDU

Thanks for any input.

Gerald
Owner / Artist
www.imperium-design.com

[lakeside]

have center of part at X Y 0
mount on plate with dowel pins of center in X or Y
flip part

[carguy327]

OK Mike,

It may be the heat or what you are describing to me is making me sweat.

This is what I'm interpreting...

Mount a plate on the table with dowels in it, in a logical NESW and centre pattern.
mount properly aligned material to a similar mount that fits into the one on the table.
Hope to hell you measured properly to ensure alignment when you flip it.


I've done flips in foam block but any screw ups are easily sanded out. I can't afford too much of a misalignment.

Oh..Z depth may be an issue. This flip would be 90 degrees CCW..if I do it. Of course I can break it apart and glue the pieces together...hmm.

I think I need a bit more info before I feel comfortable doing this.
Could you elaborate a bit?

Thanks

Gerald

[tobyaxis]

Originally Posted by lakeside have center of part at X Y 0 mount on plate with dowel pins of center in X or Y flip part

I too use Lakesides Method but with extended dowel pins and a 1-2-3 blocks under large the parts to be Machined. This way it is easier to get a hand under the part when you have to flip.

[Geof]

Do you have any pictures? Without seeing what you are intending to make it difficult to give specific advice. Are you going to be flipping 90 or 180 degrees, how is the part held, will the machining be right around 360 degrees or will the part always have a flat side, can you leave two projections opposite each other that can later be finished by hand. Without this type of information it is only possible to give generalized advice which can be difficult to interpret and apply.

[carguy327]

A client has given me part for some contraption form the 70's.
It's been doubled in size...

Thanks for the info so far,

Gerald
Owner / Artist
www.imperium-design.com

[Geof]

I copied one of your pictures and drew a couple of lines on it. It looks like the row of slots could be done from either side; or part way through from each side to meet in the middle. What I would do is put two holes all the way through in the two end slots. Naturally to do this you know where these holes are with reference to the work zero. After you flip you dial in to these two holes and then work backwards from their location to get the work zero location.

Alternatively you tap fixturing holes on the flat side that is out of view in the picture I copied. It actually looks like the part will be fastened against something on this side. Then you secure your blank to a plate held in vise jaws and find the coordinates for a corner of the the plate relative to your work zero. You machine the first side, turn the whole assembly over in the vise, relocate the work zero from the same corner and finish the second side.

Or combine the two methods.

[unterhaus]

Is that an armrest for a car?

It's also important that you tell us what material you are using. I usually make things that can end up being held in a vice for their last operation. The thing you are making probably doesn't fit in that category.

If part of the object you are making is going to end up not being readily seen, you could machine your registration features into it. Or in this case, you have all those slots, you could make a fixture that had keys that registered into those slots. The first operation makes the slots, you mount the fixture to your machine and put the slots on the keys.

[lakeside]

how ever you decide to locate part if you set you X Y 0 befor drilling and reaming part you now have set zero for part if you flip in X try to keep Y the same also you can machine in a location tab and remove later