RFQ CNC Lathe Work

[Exoray]

This is a rehash of a request I originally posted in November 2008, I had awarded it to 3 shops that gave me quotes and all 3 failed to deliver any parts so I'm hoping round two gets better results...

Quantity 25-50 depending on price...
Material 6061-T6
Tolerance isn't all that important so lets say +/- .005"

Here is a rough idea of what I'm looking for... YES the cuts are DEEP and THIN! They are as thin as 0.0470" and .2500" deep, I know tool stability issues might arise so I'm making this point clear and upfront... Overall diameter is 1.5000" and it's 1.7165" tall...



And a rendered cutaway...



I do have detailed drawings and dimensions of the final design that will be provided on request to those interested in quoting...

[howd]

P M sent.

[Geof]

I am not interested in quoting but have a suggestion/question:

If I was doing a part similar to this I would possibly do the fins on a milling machine using a slitting saw interpolating around the OD. It would be trivial to do this and make a 0.25" deep groove.

However your picture seems to show a radius at both the root and crown of the fin; is this correct and is this necessary? If square corners are acceptable you could consider not limiting yourself to a lathe operation.

[Exoray]

Originally Posted by Geof However your picture seems to show a radius at both the root and crown of the fin; is this correct and is this necessary?

Yes, both radius are necessary...

[Donkey Hotey]

The first and last slots are also truncated. That rules out using a ground slotting tool to do the job. In fact, unless a custom tool is half-ground for each of the end grooves, those shapes are not even possible (not at a price you'll want to pay). Also: a half-ground tool like that is going to push away from the radiused side (you're asking for trouble).

Can it be redesigned to have identical, full-width slots in all locations?

And is the square bottom on that deep hole necessary? That's going to be another tough one.

Edit: it looks like that hole is threaded. Whether that is a full-depth thread or not will make a difference. What is the other hole for? Is that a precise-depth countersink or just a hole chamfer?

[snovak240]

PM sent with quote

[Exoray]

Originally Posted by Donkey Hotey The first and last slots are also truncated. That rules out using a ground slotting tool to do the job. In fact, unless a custom tool is half-ground for each of the end grooves, those shapes are not even possible (not at a price you'll want to pay). Also: a half-ground tool like that is going to push away from the radiused side (you're asking for trouble). Can it be redesigned to have identical, full-width slots in all locations?

As I have notified people that have inquired about giving a quote for the part, that part of the design can be altered the overall height of the part can be increased and the two outside slots made identical to the rest if there is a significant savings...

And is the square bottom on that deep hole necessary? That's going to be another tough one.

Nope regular drill profile is fine...

Edit: it looks like that hole is threaded.

Yep, threaded 1/4" -20 to a depth of about 1" not critical...

What is the other hole for? Is that a precise-depth countersink or just a hole chamfer?

Nothing all that precise...

I go into more details when I email those that are looking to quote me, this is a cosmetic piece so there is room for a little give and take although I would like to keep it as true to the design as possible...

[Donkey Hotey]

Originally Posted by Exoray ...this is a cosmetic piece so there is room for a little give and take ...

That's a good thing to share. Just a little edjumication on this stuff:

Good cosmetic finish on those rounded fins and the grooves, will necessitate the grooving cutter being rigid. To be rigid, it needs to be as thick as possible. That means that one of the two outboard grooves should be eliminated and the whole rib pattern shifted over one-half spacing of the fins. You'll end up with even thickness on all of the fins and the grooves will be uniform.

Also on those fins: the grooving tools can have a rounded nose but it can cause chatter problems. A better choice is a square bottom groove (as Geof already mentioned). A CNC can easily cut that outside radius with a square-nose grooving cutter but a radius at the bottom of the pocket will require special inserts (that will be invisibly passed on to you in higher quotes).

I'm not trying to hijack your quote, just trying to help you get the best part for your money. Some of the features can inadvertently push up the cost of the part or limit the quality you get for your money (neither of which is good for you).

I'd bid the job but I'm afraid that I'd be trying to make exactly what you showed. That would push my quote beyond what you'd be willing to pay. This may be why the previous winners of the quote never came through.

[Exoray]

I fully understand everything you are saying but the idea at this time is to have it made as is, as you can see from the above pictures I have had this part made before I'm aware of how hard it is to make and the cost associated with it...

Fin count is important so dropping a fin is not an option nor is removing the radius at the bottom of the grooves... The overall profile appearance needs to remain as close as possible...

As I have said the option of an overall height increase to equalize the grooves is pretty much the extent of deviation I'm looking to do at this point, and that will depend on the difference in price...

Again I know it's a hard part to make as is, that is why I'm shopping it around to people that might have more experience and better machinery rather then doing it myself...

[keilola]

PM Sent

[snovak240]

Sent quote on original part configuration.

[t.labs]

would like to quote but need more detailed drawings. It would be appreciated to get the drawing ASAP. Thanks.