FIXTURING IDEAS????

[M_CODE1]

Wanted to see if anyone has any ideas on the best way to fixture up a part.

 

Part is 36in in diameter 3/8 plate. Gets a 3/8 x 45 chamfer around the whole OD, and a 7in flat milled on the OD. Another problem is that our biggest machine has only 32" on travel, so we will have to turn the part 90 to finish the chamfer.

 

Has anyone has an luck with magnetic clamps or some kind of vacuum plate? If so what vendor do you use?

 

Thanks for any input.

[MACHINEMASTERG]

how about a spin fixture part bolted to fixture which sits on top of another fixture plate they are pined at the parts center line and then outside of the parts dia thru the top into the bottom do all you work on 1 half then pull the pins after removing toe clamps that hold the fixtures down .The part stayes clamed the the top fixture and the whole thing spins 180 degrees repin reclamp run 2nd side ....

[M_CODE1]

if my part stayed clamped to my top plate, I would still not be able to get the the cutter in that spot to mill the chamfer.

 

I'll probally have to just spin the part by hand, and reclamp it to the plate.

 

Looked at the magnetic clamping and they looked too expensive for this part.

[Rick Henrickson The Boeing Co.]

do you have any through holes that are threaded?

[M_CODE1]

nope, no thru threaded holes, just a chanfer and flat is the only features on the part

[PERRY C]

Can you clamp 2 parallels to the table to create a vee block out of cold rolled steel and toe clampe it down. machine half then you can turn it 180 deg. and machine the other half, at least you wouldn't have to pick center back up.

HTH

[MetalMarvels]

If you had access to a vacuum setup, this sounds like a perfect application. However, getting the vacuum setup can be a little pricey. For my own shop needs, I went with a portable refrigeration-type vacuum pump and a 10 gallon air tank as a vacuum reserve. I used 3/8 flexible tubing to carry the vacuum to the fixture. Works well for my purposes, but it is probably not as robust as one of the purpose-built vacuum systems.

 

For the vacuum to hold well while using a solid sub-plate, you need to mill a grid of "runners" into the surface of the sub-plate that connect to the vacuum inlet - under the footprint of the plate to be held. I typically use a 1/2 inch grid that I cut with a 1/8 inch diameter ball mill. That allows the vacuum to be "distributed" across the bottom of the plate to be fixtured. I use a closed-cell neoprene "cord" that is 1/8 inch diameter and held in a 0.100 wide by 0.100 deep groove around the perimeter of the part to provide the vacuum seal.

[MACHINEMASTERG]

the whole top fixtue spins you just move your clamps to the back side off the part

[Goldorak]

Mike, first of all , how many plates are you going to machine with this fixture ?

 

if you got 10 , go simple as possible , if 10k maybe you will need to spend money on a more complex set-up

 

 

IMHO !

[M_CODE1]

Looks like its about 250 EAU on this part.

[Kevangel]

If you have some kind of mounting plate would 2 dowel pins to rest part against (similar to V-block contact) then machine 180 degrees or more, unclamp and rotate ,etc work for you? It may pay to make a fast and dirty fixture for this. Mounted plate with a rotating plate on top (dowel holes in center for location) then 4 dowels that would allow biggest part to nest while being clamped and if diameters vary, shim between part and 4 o.d. location dowels. You will have to move clamps...

[MACHINEMASTERG]

Mounted plate with a rotating plate on top (dowel holes in center for location) .....yes like that

[Kevangel]

I actually gave you 2 different ways in my above post...little confusing maybe..

[Rosko]

Are you allowed any fixturing holes in the part? I agree with the nested in 2 dowel pins idea, but it would be nice to take a continuous cut around the majority of the part without jumping over clamps.

 

Also, if one large magnetic plate is out of the question then maybe a few smaller ones spread out?

[MACHINEMASTERG]

quote:

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but it would be nice to take a continuous cut around the majority of the part without jumping over clamps.

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he dosnt have the travel so he has to do 1/2 and 1/2 ...

top fixture plate has 3 pins 1 in center to spin around 2 thru the top fixtureso when you spin it it will be 180 degrees around put these out side off the part dia by maybe 2 inch pre drill and tap holes in the outside of part dia in the fixture for toe clamps on both sides of the parts center line for clamps do 2 on 1 side spin fixture same 2 taped holes for clamps ...NOW put up part center of part is center of rotating pin do 1/2 the part in the front of center then pull the outside pins spin fixture put pins in clamps on the back sidethat is now finished being cut remove front clamps that are in the way and machine the other 1/2...

[M_CODE1]

I dont think they would allow fixturing holes, since this part is the lid for some type of pressure cooking pot.

 

Thanks for the the ideas every one, I think we are going to go with the quick and dirty way of putting two dowels in a plate, machining most of it then moving the clamps rotating it and then mahining the rest of it.

[Rosko]

quote:

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he dosnt have the travel so he has to do 1/2 and 1/2 ...

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I realize that but will two clamps be enough to hold down such a large part? I was picturing clamps around the perimeter in at least a few more spots and having to machine around and then later move them and go back. The spinning fixture idea sounds good though.