RFQ - What am I doing wrong?

Fish On · Dec 23, 2022

Stirling said:
Wait. You pulling out leg or was that actually a real thing?

Was a real thing, or at least, so the guy says. Methinks the dude realized that some of the shit he was posting made him look like an absolute moron, and tried to play it off as some psychology experiment.

He'd been an occasional poster for years with 'normal' type posts and has continued to be for some time since, so I think he just went off his meds for a bit and came up with a weird excuse to save face.

Posts 35 - 76 in this thread

Not happy with new Pressbrake

Okay, so the brand new Betenbender press brake showed up today, there're what appears to be a chain gouge on the bed that will need to be stoned down flush before putting the bottom die in. The upper die bolts to pinch the die won't tighten up, so I need to take a tap to the holes and chase the...

www.practicalmachinist.com

DDoug · Dec 23, 2022

Stirling said:
Wait. You pulling out leg or was that actually a real thing?

Post #76

Not happy with new Pressbrake

Another guy who can't read. He bought the pressbrake at the show! Got that? It wasn't a machine on display. It was custom built for the customer who ordered it at the show! The machine was built after the show. And any issues were dealt with immediately after delivery. The only negative press...

www.practicalmachinist.com

DDoug · Dec 23, 2022

Fish On said:
Was a real thing, or at least, so the guy says. Methinks the dude realized that some of the shit he was posting made him look like an absolute moron, and tried to play it off as some psychology experiment.

He'd been an occasional poster for years with 'normal' type posts and has continued to be for some time since, so I think he just went off his meds for a bit and came up with a weird excuse to save face.

Posts 35 - 76 in this thread

Not happy with new Pressbrake

Okay, so the brand new Betenbender press brake showed up today, there're what appears to be a chain gouge on the bed that will need to be stoned down flush before putting the bottom die in. The upper die bolts to pinch the die won't tighten up, so I need to take a tap to the holes and chase the...

www.practicalmachinist.com

So we must always look at his postings with that in mind..... :hitsthefan:

LOTT · Dec 24, 2022

Corry said:
I'm self-funded here and spent close to $500,000 so far. For a large company, this is chump change. And they certainly wouldn't quibble about $50k for a part. But I'm on a shoestring compared to that. For a self funded, one man research shop, I'm probably spending at the upper tier.

You've spent a half million out of pocket on a side project? I'd stick to doing whatever created that income.

triumph406 · Dec 24, 2022

Corry said:
, I could machine my own set screws that were 0.001" or better.

What I had to do way back in the past, when we used setscrews to align a part was to drill and bore the hole, then tap down to a depth leaving the remaining bored hole. I think the bored hole diameter was .20", and it's length .40" so a 2:1 length ratio, and the tap thread was 1/4-28.

We then took 1/4-28 setcrews and turned the end diameter to be a tight slip fit in the bored hole. The end was given a short 10deg taper to aid in location. It worked OK.

triumph406 · Dec 24, 2022

Fish On said:
Was a real thing, or at least, so the guy says. Methinks the dude realized that some of the shit he was posting made him look like an absolute moron, and tried to play it off as some psychology experiment.

That was my take on it too.

He embarrased himself and tried to a make seemingly implausible excuse for his absolute stupidity.

jccaclimber · Dec 24, 2022

LOTT said:
You've spent a half million out of pocket on a side project? I'd stick to doing whatever created that income.

OP has already said they are a software engineer. If we assume they’ve been doing that since they graduated 16 years ago I’d be surprised if their W2 income doesn’t at least have a 2 or 3 in front of the 5 zeros, and wouldn’t be shocked if it was a 5 or 6. Maybe a bit more if they’re really good. Some people play golf, some have a big boat, some new cars every couple years. Sounds like the OP works on the widget. They’re probably counting machine tools they bought along with rent for shop space. I’m guessing not their time, but it all adds up fast. For that sort of coin one could have hired an expert though. See my comment a few posts back about software companies making hardware and hardware companies making software.

triumph406 · Dec 24, 2022

If the OP has that kind of coin, then maybe a machine tool salesmen needs to contact him before the tap closes off.

joecrs · Jan 12, 2023

Corry said:
I have never quoted out a part in my life, so be gentle . I also am just my own private job shop, so the only RFQ's I've seen are my own (small research project) I've probably got something really stupid in this drawing making it so I get no quotes, or no replies. In my RFQ I even specify I'm new at this, and if something looks stupid, talk to me and help me to understand. I get it that most shops are busy now (see the thread with the GBI), so most don't want to take the time to "educate me", but I did figure, for a sinker EDM, this would be an easy job. A bunch of conical divots (seats for conical set screws) and some small holes. I relaxed the tolerances, basically under advice from an EDM dealer, to say I don't need parts run on a CMM afterwards, and I'm asking for more than I need, so if there happens to be a reject in the bunch, I have extras. Any EDM made after about 1995 should be able to hold 0.0002", and the angle tolerances are good for a manual rotary (I think) or a fixture with angles cut in. I figured this would be a "gravy" job (easy, low time, pays well). Only complication would be fixturing, since it is rather long. (Yes, I'm also the idiotic mechanical engineer who designed this stupid thing...there's no way around having this noodle. There are parts with tight tolerances that fit over it to stiffen things up, but I need to assemble moving parts onto it, and this will be a bearing surface once hardened and nitrided). Part is from maraging 300. I have some ground, but not straightened stock. I also bought some new stock to have straightened then ground (since I think that's the order of operations?) I also don't mind a shop quoting the stock, grinding, and straightening, and said so in my RFQ.

If I have to, I'll buy a used sinker EDM. They run about $40,000 (Plus consumables...ick) in my area with the length capacity for the part. Trying to not spend that much, and not really spend 1/4 of that (since at that point, since I expect to break a lot of these, it would be more worth it to buy the machine so I could make more as I break them!). Looking for 20-30 of these...

Thoughts? Takers on the part? Help?!
View attachment 382041

I would not touch that part as designed and if I had to guess you will not even find anyone to quote it as designed. First question is these are set screw dimples and you have a +/-.0004 tolerance not to mention the radial tolerance, seems a bit extreme, If you designed this I think you need to have another look. Again not sure of function but what is the tolerance on the tapped holes these set screws thread into. I have been at this for 37 years and never saw a part that is like this and as I said even if you find a way to make it how are you going to check it , in my opinion that part is not something that can even be manufactured unless you are willing to throw tens of thousands of dollar at it

Eddie Draper · Jan 12, 2023

Something nobody has mentioned: There is a high risk of bending during Nitriding. Crankshafts are held in a straightening frame during this process, and occasionally have to go back in the oven for restraightening after measurement. You will need to get rid of the Nitride "bloom" as well, which could affect your v precise diameter. Grinding to diameter should have been the last job, as it could include a straight line finish.

And, BTW, you could easily have ended up with parts 1/25.4 the desired size, because I can't see that it says inches!

Eddie

usolutions · 2023-01-19T02:01:52-0600

Why not fit lobes before nitriling?
Why not make spline shaft and wire-edm lobe collars with correct offsets, and glue in place for axial positioning using jigs?
Apart from most of folk here, I am not a machinist, I come from automation engineering background. I have been in position that in my head I found the only best solution, but as it later turns out it is stupid to get married to, and benefits dont matter that much, but cons are underestimated.

If you are so so so into thermals, get glass lab/optics manufacturer, they use glass scales for a reason, I think you should be able to get monolythic device with lobes/collars made from one material up to your overall tolerances.
Also why not make it all from fine grain tungsten carbide, it has even less coefficient of thermal expansion, gives zero fuck on being annealed, you dont have to worry about deflection, gravity wobble as it is rigid as fuck compared to your original material, does not need heat treat, no risk of bananaing the part during heat treat, can be easily obtained ground. Probably can easily heat fit everything on to the shaft with just dunking it into liquid nitrogen, whilst heating collets to couple hundred degrees C

These are not even machining questions, it is design questions.

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RFQ - What am I doing wrong?

Fish On

Hot Rolled

Not happy with new Pressbrake

DDoug

Diamond

Not happy with new Pressbrake

DDoug

Diamond

Not happy with new Pressbrake

LOTT

Hot Rolled

triumph406

Titanium

triumph406

Titanium

jccaclimber

Hot Rolled

triumph406

Titanium

joecrs

Plastic

Eddie Draper

Plastic

usolutions

Plastic

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