thread milling?

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freman
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Re: thread milling?

Post by freman »

Rolled threads are stronger than tapped threads. Bicycle spokes have rolled threads for that reason. The thread o/d ends up bigger than the spoke diameter since nothing is removed.

Often, special high tensile bolts , like for con-rod caps are rolled threads.

High quality, precision ball-screws are rolled not ground.
GeneFC
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Re: thread milling?

Post by GeneFC »

The so-called "form taps" are not the same as "rolled threads". The material is moved rather than cut in both cases, but the rolled threads will be stronger than the formed threads. They also have a much better profile. The form taps leave a strange profile that is not the typical vee-shape.

The best ball screws are definitely ground. Rolled screws are cheaper and less accurate. As an example here is an excerpt from the Nook Industries catalog.

Code: Select all

Nook uses the latest in CNC thread rolling technology and state of the art CNC induction heat treatment to
manufacture a rolled screw with accuracy approaching precision ground at a substantially lower cost.

They fill the need for applications that don’t warrant the expense for ground screws but still require more precise
positioning than that offered by commercial grade screws.
Nook is one of the premiere ball screw manufacturers in the US.

Enough off-topic. Back to regular programming. 8-)

Gene
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freman
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Re: thread milling?

Post by freman »

Oops, got the ballscrew thing back to front . Thanks for the correction.
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jarhead_h
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Re: thread milling?

Post by jarhead_h »

sliptonic wrote: Sat Jul 10, 2021 5:30 pm Path->Specialty Operations->Threadmill.

I think it's an experimental. I've never used it because I don't have any threadmill tools. It's mlampert's baby.
This is the only place I can find anything that says "thread milling" so far, and I also have not used it, yet. Definitely going to be in the near future, though. I'm not sure if it's meant to be used with say a helix op? Whatever, it'll get figured out and become something that future noobs will take for granted. And I know you guys actively developing FreeCAD probably don't hear it enough, so thank you.
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GeneFC
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Re: thread milling?

Post by GeneFC »

jarhead_h wrote: Mon Sep 20, 2021 6:53 am I'm not sure if it's meant to be used with say a helix op?
I have not used thread milling, either, but I believe the helix is built in. The TM operation uses G2 and G3 codes, which already have helix behavior as part of their intrinsic functionality.

Try it and see.

Gene
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jarhead_h
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Re: thread milling?

Post by jarhead_h »

GeneFC wrote: Mon Sep 20, 2021 3:05 pm
jarhead_h wrote: Mon Sep 20, 2021 6:53 am I'm not sure if it's meant to be used with say a helix op?
I have not used thread milling, either, but I believe the helix is built in. The TM operation uses G2 and G3 codes, which already have helix behavior as part of their intrinsic functionality.

Try it and see.

Gene
I can't at the moment.
(1)I've tried enabled experimental commands in preferences and I still can't find the icon for thread milling. Using .20
(2) I don't own a thread mill tool yet
(3) the tool I have in the que to buy does not fit the router I am currently using as a spindle.
(4) I just posted a vid on my channel (in my sig) explaining that the machine isn't rigid enough to handle aluminum, so I have to push up the scheduled overhaul of the entire machine.

The overhaul involves using the router to cut styrofoam patterns for use in Lost-Foam casting. The base of the machine is several layers of OSB glued together that has to be coated in epoxy top and sides while the aluminum castings are being processed. Then the whole thing has to be bolted back together with the new 2 1/4HP spindle that can take a 3/8 shank for the tool from McMaster(or 5/16, because the other option from Micro uses that), then I have to do the full shakedown tightening everything, dialing in the steppers, and then the tram.

After all of that, I'm hoping that the machine will handle cutting 4140 with a VERY conservative step-over and then single point threading for 1/2-28.

Hoping to have all of this in play by December. I'm sorry that I can't be more help, yet. It would be kinda cool to be the first on the internet with a vid doing this.
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GeneFC
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Re: thread milling?

Post by GeneFC »

jarhead_h wrote: Sun Oct 17, 2021 3:39 pm I'm hoping that the machine will handle cutting 4140
That should be entertaining with a router.

Wear your safety glasses. :o

Gene
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jarhead_h
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Re: thread milling?

Post by jarhead_h »

GeneFC wrote: Sun Oct 17, 2021 4:11 pm
jarhead_h wrote: Sun Oct 17, 2021 3:39 pm I'm hoping that the machine will handle cutting 4140
That should be entertaining with a router.

Wear your safety glasses. :o

Gene
I don't have a lathe. The workpiece is going to be over 12inches long. The machine-base is going to have a flanged hole installed in the front to allow for very tall objects to be cut vertically. It will accept a flanged plug. So the workpiece sticks up through vertically just enough for the new clamping system, something like an improvised mod-vice from NYC CNC. Designing the whole thing as an integrated system.

And besides, if This Old Tony can make a router that can cut a functioning sprocket out of 4140 roundstock for his mini-bike, I'm sure that I can fail spectacularly merely reducing a diameter to threading size.
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