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Order of progression - Where to start....

SeymourDumore

Diamond
Joined
Aug 2, 2005
Location
CT
Guys, probably a stupid question, but I'm throwin' it out there anyway.

So I've got 6 sets of assemblies to make: Component A, B, C, D, and E.
Component A has an internal thread of M50x1, and it is a fixed, permanent item.
Components B, C D and E are externally threaded M50x1, and they are interchangeable ( few differences on various features ) and they are "consumable" items to mate with A.

Component A is likely never to be replaced ( though they may need new assemblies later ), while the others are going to be needing spares in the future.

So, for this first time around making the pieces: What would you start with?

1: Start with Component A and mate all others to it
or
2: Make all of B, C, D and E first, and then mate A?

Obviously if the design is correct and tolerances are held they should all fit just fine, but this is a brand new ( not mine in any way ) contraption
and I normally shit bricks with these kind of projects until all is well at the end.
In this case the material bill is just north of 10K and I'd rather save the trouble for everyone involved.

My current thinking: Go with Option 1, so if the proverbial hits the fan I only need to re-do those 6 pieces.

What say You?
( Told you it was going to be a stupid question! )
 
Huh? Make the six external M50x1’s, those are your gauges. Fit everything external to them. Though in the real world with tolerances I’d aim middle-of-the road on the six “thread gauges” and just north of middle on the ID parts.

Worst case, run another pass on the ID part that’s tight. I’d not even think of starting over on the externals in that case- bass ackwards IMHO.
 
Option 1.....no doubt about it.

If you can't get component A right which is the tool holder/fixture or whatever, then why waste more time making 5 or 6 more F**K Ups?
 
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Just like those $5.00 pins you made last week, the ones that get an off the shelf 1/2-20
nut screwed on the end... You made the threads right, and there is nothing to worry about.

Now if there is a post machine heat treat, or a coating... Might be worth doing some extra
research on shrinkage(but the water was cold), or send out a sample to see where it goes..

I have one 13-8 pin I make on occasion.. 13-8 is well documented as to shrink.. TIGHT tolerance,
and a thread.. When I ship them, they are all oversize, after heat treat, they are perfect
(in tolerance, only carpenters can make things "perfect"), though
not as shiny.. I like the Ovee gages for stuff like that.. Basically thread wires in spring form,
really easy to run your PD .0004" over or .002" under without having to buy new ring gages.

Don't sweat it, you've made threads before.
 
No post operations.
Material is Duplex 2205 for detail A, and 6/4 Ti for all others.
(Sidenote: Duplex sucks, almost as much as Inco718 !!! )
 
Component A is likely never to be replaced ( though they may need new assemblies later ), while the others are going to be needing spares in the future.

Given the big material bill, do you have enough material drop to knock out an "as machined" thread gauge portion of Component A? It would make knocking out future copies of B/C/D/E a bit easier - if they fit in the gauge, they're guaranteed to fit in the A parts out in the field.
 
I love duplex 2205, turns good, mills good, I make lots of fancy parts out of it. Just gotta get the SFM right, too slow it gums and tears up, too fast it cooks cutters like anything else will, in the happy zone its almost butter :)

As to part order, I usually like to tackle the worst one with the most chance of screw up first(and longest to get replacement material if it goes bad) or whatever gets assembled first if I have to split deliveries, get that out the way, less stress afterward. I'd likely go with option 1 in your case, sounds like there's more of those to make than the other ones.
 








 
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