Short run, small part

[Question Boy]

I've got the critical dims shown on the PDF. The through bore is the most critical, most others + or -.05mm. Open to suggestions to make it less costly to machine.

Material: 41L40 (or other free machining steel, open to suggestions)

Qty: Please quote for qty 100 and qty 200.

Nothing crazy on surface finish. Surface finish on part must be smooth, no tooling marks / nice edges / burr free... a good quality turned item. No additional finishing processes needed (no plating, no polishing, no tumbling).

RFQ open through 10/14, though I'd be happy to award this sooner.

Turn around time: Please make sure your quote includes a realistic turn around time.

QB

 

[Dualkit]

I see 2x 15.84, yet the front of the part shows a taper. Also the bore basically has a +/-.0003 tolerance on diameter which drives up costs for those of us who pay attention to tolerances. That is a press fit call out, and you have a tapped hole for a set screw, I would think a slip fit of +/- .001 would be sufficient since your securing it with a screw, and a lot cheaper to make.
Don't mind me, there will be plenty people in here bidding like the tolerance is +\- .005 or think the +.013\-.003 is in inches and wide open, and they can do it with a drill.

 

[Question Boy]

I see 2x 15.84, yet the front of the part shows a taper. Also the bore basically has a +/-.0003 tolerance on diameter which drives up costs for those of us who pay attention to tolerances. That is a press fit call out, and you have a tapped hole for a set screw, I would think a slip fit of +/- .001 would be sufficient since your securing it with a screw, and a lot cheaper to make.
Don't mind me, there will be plenty people in here bidding like the tolerance is +\- .005 or think the +.013\-.003 is in inches and wide open, and they can do it with a drill.

The 2x you're looking at is supposed to indicate that both sides of the tapered flange part are the same. I did not dimension the cone-like taper on the front. This is (obviously) not a finished drawing, so I'll let you off the hook for being confused.

The last machine I ran was a mid 80's Okuma gang lathe and I had no problem holding .0005" in an identical part in aluminum, and I'm a complete amateur. I was expecting a newer machine, programmed and set up by an experienced user would have no problem holding the same in free machining steel. So far the (decent) quotes coming in lead me to think I am right.

This design (small chain drive with closely spaced shafts) could probably tolerate up to .001" oversize on the bore, but .002" over the shaft size will cause the chain to go tight and loose with every revolution of the sprocket (as the set screw pulls the sprocket off center), and that will look like crap.

And if someone thinks the tolerance on the bore is in inches, I'd expect them to be consistent in their mistakes and I should then get a really high quote for my 20" diameter part.

QB

 

[Dualkit]

The 2x you're looking at is supposed to indicate that both sides of the tapered flange part are the same. I did not dimension the cone-like taper on the front. This is (obviously) not a finished drawing, so I'll let you off the hook for being confused.

The last machine I ran was a mid 80's Okuma gang lathe and I had no problem holding .0005" in an identical part in aluminum, and I'm a complete amateur. I was expecting a newer machine, programmed and set up by an experienced user would have no problem holding the same in free machining steel. So far the (decent) quotes coming in lead me to think I am right.

This design (small chain drive with closely spaced shafts) could probably tolerate up to .001" oversize on the bore, but .002" over the shaft size will cause the chain to go tight and loose with every revolution of the sprocket (as the set screw pulls the sprocket off center), and that will look like crap.

And if someone thinks the tolerance on the bore is in inches, I'd expect them to be consistent in their mistakes and I should then get a really high quote for my 20" diameter part.

QB

I think you asked how to reduce costs on your part, I responded with an appropriate answer and you get all snotty. Also aluminum and steel are quite different. Have you ever heard of tool wear? Also your off the shelf pin set
has .001 graduations, that won't even be good enough to inspect your parts.
There are a lot of desperate hacks on these boards who disregard tolerances
in the hope of getting work. They figure the customer won't even inspect the parts and they will be ok as long as they fit. It seems like +/-.0005 goes for the same price as +/-.005. I was just trying to warn you of that. So don't ask questions if you don't like the answer. Hopefully you will pick the cheapest responder and you will pay for useless scrap.

 

[Question Boy]

I think you asked how to reduce costs on your part, I responded with an appropriate answer and you get all snotty. Also aluminum and steel are quite different. Have you ever heard of tool wear? Also your off the shelf pin set
has .001 graduations, that won't even be good enough to inspect your parts.
There are a lot of desperate hacks on these boards who disregard tolerances
in the hope of getting work. They figure the customer won't even inspect the parts and they will be ok as long as they fit. It seems like +/-.0005 goes for the same price as +/-.005. I was just trying to warn you of that. So don't ask questions if you don't like the answer. Hopefully you will pick the cheapest responder and you will pay for useless scrap.

So you chime in with your "don't mind me" everyone's going to miss quote because they'll be confused about the bore tolerance comment, then you misread the drawing with regard to the front taper, then suggest a change to open up the tolerance on the only feature that I said needs to be close, and I point these things out to you, so that makes me "all snotty".

Good grief. You would probably get more business if your online personality were a little less acrid.

QB

 

[Larry1]

.0003 to .0005 tolerance is hard to believe on more than a few machined parts. I would not quote.

 

[Question Boy]

.0003 to .0005 tolerance is hard to believe on more than a few machined parts. I would not quote.

Did you look at the drawing? The tolerance range on the bore is .0006". If you looked at the drawing an saw a .0002" range, please don't quote. If you couldn't be bothered to look at the drawing, please don't quote.

QB

 

[Larry1]

Thanks for the reply but it was meant for the guy who's attitude you did not care for. I do not want to quote on your work. Have a good day.

 

[Question Boy]

This RFQ has been awarded.

Thanks to all who bid.

QB