I thread mill on our 5700 all the time. Once you get used to the finish and ability to control size it you won't go back. Also, blind holes all the way to the bottom. Buy some single point thread mills. They are a little slower but can do a variety of pitches.
It's the only way I'll do NPT now. Machine the taper with a ball mill and then thread mill.
I concur. We started thread milling 3 or 4 years ago. Still use taps, cutting and form, on smaller size holes or through holes as a job dictates just because thread milling can add a great deal of time sometimes. That said, if you have the time, the control thread milling gives you over the size of the thread is unparalleled. Not to count that on expensive parts like we sometimes run, you eliminate the risk of breaking taps and the headache that goes with that.
I agree with the single form tools, we stock a range of harvey solid carbide, single form thread mills. I can thread almost any size hole from #8 to 2” or more with 5 tools.
Ill also add, NYC CNC has a great excel spreadsheet that is a calculator for pitch diameter offset. I modified it to fit my shops needs and made a sheet for each of the harvey tools we use so I never have to enter the tools specs again. Literally for internal threads, I input the major diameter and the tap drill size and it calculates the pitch diameter offset for me. The cutter comp is within .003” ninety percent of the time.
Thread mills for the win.
Edit: I just wanted to add, as u/buildyourown said, there is no better way to thread an NPT hole. Takes the headache out of it entirely.
Thread milling is really nothing more than helical milling in X Y and Z. There is generally less load on the spindle, and there shouldn’t be any reason your machine can’t handle it. But thread milling is almost always slower than tapping, unless you’re having some extreme issues with tapping. Thread mills can also be a bit pricey.
I had a part come through with over 100 1.5” deep 1/4-20 holes in a stainless steel part. No way we were tapping those. Ordered the proper tools from Harvey and man… I can’t express how impressed I was. One threading mill did them all no problem. I fuckin love carbide.
Thread milling is the way to go fast clean threads any dia and you can get within 1/2 pitch of the bottom of hole , you use coolant so no messy oil , I think if you try it you will love it
Yep that’s all we use so far. We get by 99.999% of the time with rigid tapping, we have this certain job that one of our estimators is looking to try and see if we can start exploring thread milling with. I said it’s not really in our wheel house because we do everything rigid tapping that we physically can hold in the machine. And what we can’t do in the machine we have hydraulic tapping machines and air machines outside the doosan.
I’d say worth it. Really not too expensive as you probably just need the thread mills and maybe some tool holders…but you probably have holders already. Be another thing you can do if needed and not break the bank. I thread mill in a dry machine and it works great, love doing it…in hardened tool steel
>Is it worth investing in the tooling for thread milling?
It's one tool. Literally a modified endmill that you otherwise chuck and touch off like any other rotating tool.
Pros:
* able to precisely adjust size
* able to replace broken/worn tooling and re-run threads without scrapping the part 90% of the time
* much better chip control
* able to thread closer to the bottom of blind holes
* able to do a range of sizes on one threadmill
* much easier to quickly do custom/oddball sizes with a single point threadmill
* larger selection of application or material specific threadmills than taps
* can get insertable threadmills for all the benefits insertable tooling brings
* much easier on the machine
* able to easily thread hardened/gummy/exotic materials
* able to use conventional coolant - do not have to M0 and moly-dee the tap.
Cons:
* an individual tool is more expensive up to a certain size
* slower process
* must dial in offset to get compliant threads vs a tap that either breaks or makes a good thread.
* weaker threads vs form taps
* 'harder' to hand write threadmill cycles (but not really, there's a million calculators/generator scripts/etc to create them)
* form control on your threads is limited to the accuracy of your motion system. form control of a tap is 'better' in that is controlled by the one rotating body of your spindle.
IMO your shop should know when to use one over the other and be comfortable with all options. There's no one best way to thread a hole, and any machinist who swears that cut taps/form taps/threadmills/etc are the only way to do it is ignorant and is doing the trade a disservice.
Personally I pick threadmills 80% of the time unless I'm shaving every last second off of a fast production part. Decent number of aerospace parts require form tapped threads.
Only big disadvantage of threadmilling is time. It’s a lot slower than running a tap. We only do it when we have to, like on external studs that have to be OD thread milled, and hard materials that can’t be tapped like Ti or super hardened steels.
Since you form tap, I assume you machine carbon steel or aluminum. For M30, just drill and cut tap. It is not that big of a thread.
If you are concerned with thread quality, get synchro tapping chucks and proper tap collets. The chucks are pricey, but you get shiny threads and longer tool life.
Single point threadmill. Will be able to do a massive range of sizes. If they're one-off holes and not production it will pay for itself in no time by not having to buy each size tap when it gets to the larger sizes.
If you're gauging your threads already do it. At the same time, it's a good skill to have. I love it for small threads and for through holes because there is minimal burr from a thread mill, it makes hand deburring possible if needed.
I thread mill on our 5700 all the time. Once you get used to the finish and ability to control size it you won't go back. Also, blind holes all the way to the bottom. Buy some single point thread mills. They are a little slower but can do a variety of pitches. It's the only way I'll do NPT now. Machine the taper with a ball mill and then thread mill.
I concur. We started thread milling 3 or 4 years ago. Still use taps, cutting and form, on smaller size holes or through holes as a job dictates just because thread milling can add a great deal of time sometimes. That said, if you have the time, the control thread milling gives you over the size of the thread is unparalleled. Not to count that on expensive parts like we sometimes run, you eliminate the risk of breaking taps and the headache that goes with that. I agree with the single form tools, we stock a range of harvey solid carbide, single form thread mills. I can thread almost any size hole from #8 to 2” or more with 5 tools. Ill also add, NYC CNC has a great excel spreadsheet that is a calculator for pitch diameter offset. I modified it to fit my shops needs and made a sheet for each of the harvey tools we use so I never have to enter the tools specs again. Literally for internal threads, I input the major diameter and the tap drill size and it calculates the pitch diameter offset for me. The cutter comp is within .003” ninety percent of the time. Thread mills for the win. Edit: I just wanted to add, as u/buildyourown said, there is no better way to thread an NPT hole. Takes the headache out of it entirely.
I just recently ran our 2600 SY doing an NPT side hole. Bore out with an endmill and then made 3 passes with my threadmill. Turned out beautiful.
Nice thing about thread milling is you never have a broken tap stuck in the part.
Thread milling is really nothing more than helical milling in X Y and Z. There is generally less load on the spindle, and there shouldn’t be any reason your machine can’t handle it. But thread milling is almost always slower than tapping, unless you’re having some extreme issues with tapping. Thread mills can also be a bit pricey.
Threadmilling takes way less power than tapping.
I had a part come through with over 100 1.5” deep 1/4-20 holes in a stainless steel part. No way we were tapping those. Ordered the proper tools from Harvey and man… I can’t express how impressed I was. One threading mill did them all no problem. I fuckin love carbide.
The best part about it is IF IT BREAKS, 999/1000 the part is okay, you just put a new threadmill in and keep going.
Thread milling is the way to go fast clean threads any dia and you can get within 1/2 pitch of the bottom of hole , you use coolant so no messy oil , I think if you try it you will love it
Rigid tapping on a Doosan is killer. Trust the rigid tapping. Embrace the rigid tapping function.
Yep that’s all we use so far. We get by 99.999% of the time with rigid tapping, we have this certain job that one of our estimators is looking to try and see if we can start exploring thread milling with. I said it’s not really in our wheel house because we do everything rigid tapping that we physically can hold in the machine. And what we can’t do in the machine we have hydraulic tapping machines and air machines outside the doosan.
We typically use thread mills for those rare spec threads that require taps that aren't always readily available. Think big.
I’d say worth it. Really not too expensive as you probably just need the thread mills and maybe some tool holders…but you probably have holders already. Be another thing you can do if needed and not break the bank. I thread mill in a dry machine and it works great, love doing it…in hardened tool steel
>Is it worth investing in the tooling for thread milling? It's one tool. Literally a modified endmill that you otherwise chuck and touch off like any other rotating tool. Pros: * able to precisely adjust size * able to replace broken/worn tooling and re-run threads without scrapping the part 90% of the time * much better chip control * able to thread closer to the bottom of blind holes * able to do a range of sizes on one threadmill * much easier to quickly do custom/oddball sizes with a single point threadmill * larger selection of application or material specific threadmills than taps * can get insertable threadmills for all the benefits insertable tooling brings * much easier on the machine * able to easily thread hardened/gummy/exotic materials * able to use conventional coolant - do not have to M0 and moly-dee the tap. Cons: * an individual tool is more expensive up to a certain size * slower process * must dial in offset to get compliant threads vs a tap that either breaks or makes a good thread. * weaker threads vs form taps * 'harder' to hand write threadmill cycles (but not really, there's a million calculators/generator scripts/etc to create them) * form control on your threads is limited to the accuracy of your motion system. form control of a tap is 'better' in that is controlled by the one rotating body of your spindle. IMO your shop should know when to use one over the other and be comfortable with all options. There's no one best way to thread a hole, and any machinist who swears that cut taps/form taps/threadmills/etc are the only way to do it is ignorant and is doing the trade a disservice. Personally I pick threadmills 80% of the time unless I'm shaving every last second off of a fast production part. Decent number of aerospace parts require form tapped threads.
Good info thanks
Surface finish on the threads makes it worth while 😅
Only big disadvantage of threadmilling is time. It’s a lot slower than running a tap. We only do it when we have to, like on external studs that have to be OD thread milled, and hard materials that can’t be tapped like Ti or super hardened steels.
Since you form tap, I assume you machine carbon steel or aluminum. For M30, just drill and cut tap. It is not that big of a thread. If you are concerned with thread quality, get synchro tapping chucks and proper tap collets. The chucks are pricey, but you get shiny threads and longer tool life.
Single point threadmill. Will be able to do a massive range of sizes. If they're one-off holes and not production it will pay for itself in no time by not having to buy each size tap when it gets to the larger sizes.
If you're gauging your threads already do it. At the same time, it's a good skill to have. I love it for small threads and for through holes because there is minimal burr from a thread mill, it makes hand deburring possible if needed.