Taper pipe plugs for expanding fixtures?

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Mud

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Garwood

Garwood

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Mud said:
Do they hold the part firrnly enough against the fixture to prevent chatter when surfacing, or prevent the part from lifitng .001"?
Click to expand...
They seem to lock down very solid. No problems with roughing or finishing.

It is easy to get a part not fully seated if you're not paying attention or don't clean well enough. The parts don't want to come off, they get stuck and you need to mill some slots for a plastic tool to pry them up evenly if there aren't any threaded holes to pull on.

Only other problem I had is on me, I have them sitting up .450" on a .490" thick part. I was running the last lot of parts with my fixture made for 4 parts each batch, I just had 2. I realized I needed to tighten the screws on the pins I wasn't using so the facemill wouldn't crash. Without thinking I zipped the screw in on the first one with the impact- Destroyed it with no part to constrain it. I hope I don't do that again. If I do I won't tell you.
 
Barbter

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Garwood said:
Just to ad- I'm not a huge fan of vises. When I started out all my aluminum parts were made from big chunks of plate. Fixtures from the get go. When I started making smaller stuff I struggled with the "Buy thicker stock and turn 1/8" into chips on the flip". That 1/8" adds up and my cheapskate brain can't take it. So I'd do things like incorporate a heavy chamfer on one side or complicate the design of the part intentionally with two different profiles so the perimeter doesn't have to blend anywhere.

Previous to the expanding pins I was (and still am) using fixtures that flip onto bosses and use countersunk head SHCS in chamfers put in with reverse chamfer tools on op1 to hold them down. This is more complicated than the expanding pins. So I'm slowly moving that direction with many of my parts.
Click to expand...
Many years ago previous life, I visited Airbus Filton as they were closing a couple of cells and the thoughts were "buy the cells and the work comes"....:rolleyes:
The old horis had mostly one size fixture for a "rectangular plate" and every part was made from that size. So as you can imagine, there was a LOT of waste on all but the largest part.
I made comment to the guy showing us around who just shrugged as it wasn't his money....
Yes, I can see the whole "standardise mtl inventory, set-up reduction with quick changeover etc" philosophy, but sometimes, it's just plain lazy engineering....
 
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