What should this cost?

Mark W. Ingalls · Apr 21, 2013

Dear fellows-

From time to time I have to make one, two or up to ten of these things out of brass. I got to wondering, "What cost should I assign to these housings?"

Just a rough number... $200? $500?

Thanks,

Mark

MBG · Apr 21, 2013

Tolerances are pretty tight on those depths, other than that it is a fairly easy part. I would say around $50-60 each for up to 10.

specfab · Apr 21, 2013

I'd be more in the $100+ category on these. With 0-80 and 2-56 tapped holes, there is likely some level of careful hand work involved. Are you saying that you personally are making these? If so, you should be able to assign your cost based on your production rate, and whatever financial factors exist for the situation.

Mark W. Ingalls · Apr 21, 2013

specfab said:
I'd be more in the $100+ category on these. With 0-80 and 2-56 tapped holes, there is likely some level of careful hand work involved. Are you saying that you personally are making these? If so, you should be able to assign your cost based on your production rate, and whatever financial factors exist for the situation.

Dear Specfab- You might say I'm looking for a "reality check."

If I am making just one I can assure you it takes me much longer than an hour. Thus I am inclined to think >$60. Before going down the machine-shop-in-my-garage trail I got a quote of $500 for one of these plus a 1/32" thick flat cover with clearance holes drilled into it for the screws. I guessed the quoter was reluctant...

Dave K · Apr 21, 2013

I would say around $50-60 each for up to 10.

They way you put that, leads me to believe you'd be at $50 - $60 each if they ordered 1 or 10? No price change from 1 to 10 parts?

scadvice · Apr 22, 2013

I guess I'm the expensive one here:
(1) 150.00
(2-5) 120.00
(6-10) 97.00

Steve

sean9c · Apr 22, 2013

Interesting way to draw the part. Must be some new fangled CAD thing.

SND · Apr 22, 2013

First time around for 1 I'd be around $300-400, I'd make 3-4 and give a deal you need a 2nd

10 around $50ish.

Bobw · Apr 22, 2013

So.. .065" diameter, .059 deep ±half a thou, and then in the same hole, .078" diameter .0565±.0005 deep?

I'd like to see the equipment that can measure that step, .0025 deep, .007 wide. Down in a tiny little hole.

I bet you don't have it, I don't have it, and I bet your customer doesn't either.

Loosen up on some of the dumb stuff and I can see somebody doing it for $25, machine only on a QTY of 10.
Nothing is particularly stupid or out of whack, except for the depths on the holes, and they might be needed, but
the .0025 deep and .007 wide step tells me they aren't.... and if they were there would be a corner rad in there, and
there wouldn't be a .0025 deep counter bore. I'm guessing somebody imported a DXF or something of a press in
grease fitting and made the hole dimensions the same.

gbent · Apr 22, 2013

Bobw said:
So.. .065" diameter, .059 deep ±half a thou, and then in the same hole, .078" diameter .0565±.0005 deep?

Actually its pretty easy. For example on the counterbore use a low limit qualified length gage pin in the hole. If no radius called out, the pin should be dead sharp on the corners. It must go in the hole low limit depth. Make another gage pin thats just over high limit on the small hole. It can't go down more than high limit depth.

Thats a really BS print. I've had ones like that where someone said "Oh, make it as close as you can", and I've had ones like that where every dimension had to be on with certified and calibrated gages, 100% acceptance testing. Notes in the title block can also make make or break the job. The difference in price is orders of magnitude.

Mark W. Ingalls · Apr 22, 2013

We are using a step drill, as discussed here. It turned out that the pilot hole was critical, not just a good idea; without it, the holes came out undersized with chatter marks in the bottom. With it, everything is in tolerance. I use pin gauges to measure the diameters and depths.

This is a microwave fixture for a ~20 GHz bandpass filter, and that stuff has to be pretty well on the money...

Bobw said:
So.. .065" diameter, .059 deep ±half a thou, and then in the same hole, .078" diameter .0565±.0005 deep?

I'd like to see the equipment that can measure that step, .0025 deep, .007 wide. Down in a tiny little hole.

I bet you don't have it, I don't have it, and I bet your customer doesn't either.

Loosen up on some of the dumb stuff and I can see somebody doing it for $25, machine only on a QTY of 10.
Nothing is particularly stupid or out of whack, except for the depths on the holes, and they might be needed, but
the .0025 deep and .007 wide step tells me they aren't.... and if they were there would be a corner rad in there, and
there wouldn't be a .0025 deep counter bore. I'm guessing somebody imported a DXF or something of a press in
grease fitting and made the hole dimensions the same.

Mark W. Ingalls · Apr 22, 2013

We're microwave engineers, not machinists or CAD people. We're doing the best we can to get a-going.

sean9c said:
Interesting way to draw the part. Must be some new fangled CAD thing.

Mark W. Ingalls · Apr 22, 2013

Fellows, I appreciate all your responses, and I feel pretty good about what it's been costing to make these parts now. BTW, I've been making them on a 1947 round ram with no DRO. :eek:

I ordered a DRO this week. :drool5:

Mark

Bobw · Apr 22, 2013

gbent said:
Actually its pretty easy. For example on the counterbore use a low limit qualified length gage pin in the hole. If no radius called out, the pin should be dead sharp on the corners. It must go in the hole low limit depth. Make another gage pin thats just over high limit on the small hole. It can't go down more than high limit depth.

Thats a really BS print. I've had ones like that where someone said "Oh, make it as close as you can", and I've had ones like that where every dimension had to be on with certified and calibrated gages, 100% acceptance testing. Notes in the title block can also make make or break the job. The difference in price is orders of magnitude.

Totally disagree on if no radius called out then it should be dead sharp.

Do you make every external corner on every part you make to a half assed print dead sharp if it doesn't call out an edge break? I got my ass bit once on a first
article, machine per blah blah blah, whatever... just made the parts, apparently the spec called out drawn internal sharp corners to be .010 plus .030 rad. Woops.

If you want a sharp corner you call a sharp corner. If there is even a .003 rad on the corner, you aren't going to get a good depth on a pin, not with so little to
set on, you'll probably mangle that corner and step all to hell just putting the pin in.

Hey Mark, you got a price of over $500 because of that stupid hole. The rest of it is pretty much a no brainer.

I would suggest taking the mating part to a machinist(or 2) or posting it up here, probably half a million ways to change the drawing and make it cheaper...
without changing any of the function.

ewlsey · Apr 22, 2013

Bobw said:
Hey Mark, you got a price of over $500 because of that stupid hole. The rest of it is pretty much a no brainer.

Yep. No way to make that hole without grinding a tool. That means you will be paying for the tool. If you were making 10,000 parts, the tooling cost would be trivial. For 10, you will pay out the nose.

Mark W. Ingalls · Apr 22, 2013

Originally Posted by Bobw
Hey Mark, you got a price of over $500 because of that stupid hole. The rest of it is pretty much a no brainer.

ewlsey said:
Yep. No way to make that hole without grinding a tool. That means you will be paying for the tool. If you were making 10,000 parts, the tooling cost would be trivial. For 10, you will pay out the nose.

... yewbetcha, that step drill was (I think) ~$500...

ewlsey · Apr 22, 2013

I'm very very skeptical that you are holding that tolerance with any kind of drill. I would make a up a step drill for roughing and then use a stepped reamer to finish.

sean9c · Apr 22, 2013

There are some industry standards to b/p configuration that, when used, help ensure clarity on everyone's part.
I'm not sure how you are getting quotes from your b/p, there is not enough info there.

Old Nubbins · Apr 22, 2013

The "stupid hole" makes or breaks this part. I have some experience machining RF components and the hole diameters, alignments, surface finish, edge breaks, dimensions, etc. can all affect the final performance of the assembly. One errant burr or scratch on the wrong surface can induce a failure that may not appear until the unit is assembled and tested. Prices will be high because the potential for an unforeseen rejection is high and the method of feature measurement is not conducive to alternatives. If the dimension cannot be verified against other methods/standards/devices, then it's much more likely for three different people to get three different measurements. Although I am far from experienced when it comes to quoting, the $500 quote seems high but is not surprising. In my area I might expect $250-300 at those quantities but we see more aerospace than RF.

Mark W. Ingalls · Apr 23, 2013

[Hijacking my own thread]

sean9c said:
There are some industry standards to b/p configuration that, when used, help ensure clarity on everyone's part. I'm not sure how you are getting quotes from your b/p, there is not enough info there.

I have pondered and wondered, "Que es 'b/p'?"

[/Hijack off]

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