Speeds & Feeds, what's the relationship?

[wnchstrtnfldvlle]

I use a machinist calculator https://www.softsea.com/review/ME-Consultant.html

After inputting material and tool used, set your max RPM. It will then give you starting feed. Play with it from there.

Not positive, but I think it just scales down feed linearly to keep chip load constant.

Just to make sure I'm using this correctly. (Screenshot included for clarity)

1. I opened the tool, selected Aluminum then turning.
2. The automatically generated values populated based on the default parameters in the tool.
3. I changed the "RPM Limit" to a value of 1500 then clicked on the green square which changed everything based on my added rpm limit.
4. Which gives me a value of .0180 IPR
5. On the lathe with the 60T gear I would set the levers to "BDU" for a value of .0164 then work up from there until I get satisfactory chips. Or I could use the "BDR" for a slightly higher IPR.

Does this look correct? I know this may seem elementary to some, but I'd just like to make sure I'm doing everything correctly on my end. I was having some issues using the Machinery's Handbook to find speeds/feeds for some 12L14 I was practicing with. All of my calculations from there had suggested RPMs way over my machines capabilities. This calculator would solve that problem.

 

[MrWhoopee]

Just to make sure I'm using this correctly. (Screenshot included for clarity)

1. I opened the tool, selected Aluminum then turning.
2. The automatically generated values populated based on the default parameters in the tool.
3. I changed the "RPM Limit" to a value of 1500 then clicked on the green square which changed everything based on my added rpm limit.
4. Which gives me a value of .0180 IPR
5. On the lathe with the 60T gear I would set the levers to "BDU" for a value of .0164 then work up from there until I get satisfactory chips and surface finish. Or I could use the "BDR" for a slightly higher IPR.

Does this look correct? I know this may seem elementary to some, but I'd just like to make sure I'm doing everything correctly on my end. I was having some issues using the Machinery's Handbook to find speeds/feeds for some 12L14 I was practicing with. All of my calculations from there had suggested RPMs way over my machines capabilities. This calculator would solve that problem.

I don't know about "correct", but .016 ipr sounds like a roughing cut to me. Rapid metal removal, groovy finish.
I could be wrong.

 

[wnchstrtnfldvlle]

I don't know about "correct", but .016 ipr sounds like a roughing cut to me. Rapid metal removal, groovy finish.
I could be wrong.

That's a good point. I removed the surface finish part for clarity.

 

[dml66]

In my case, I'm working with a 0.004" nose radius (NR) tool, making a finishing cut.

Micro-100's speed & feed chart suggests 200 sfm for 12L14 steel , an IPR 25% of NR = 0.0010", and a Radial Depth of Cut (RDOC) <= 30% of NR = 0.0012". I set my rpm limit to 3000, the calculator says I need 2830 spindle rpm.



I changed the rpm limit to match my mini lathe, 2400, the calculator says I can only get to 170 sfm which isn't too far off.



Using the finish tool I set the NR to 0.005" (0.004" isn't a choice in the dropdown) and set the IPR to 0.0012". I should expect a surface finish of 10 micro inches, that would sure be nice .

 

[Karl_T]

I see you found the "finish" parameter.

I'll just mention it is a bit buggy on speeds. be sure and get everything right, then set speed limit last. In you post i see part diameter was left at 4.

 

[wnchstrtnfldvlle]

Just thought I'd show an update here without creating a new thread. Used the ME-Consultant software for some 4140 stock I sourced. So far I've just played around with aluminum. I feel like it did a great job with the initial starting point. I could feel slight ridges in the finish. In the photo there is a layer of oil so it's a little shimmery. Round two the surface was very smooth, and you could only just see the "ridges". I almost feel like that would work for a finishing pass finish if I had better chip breakage. The third try I tried lowering the rpms just to see what would happen.

Any ideas for better chip control? Online research suggested different insert geometry. I also have a 5/8" HSS blank to start some tool grinding as well.

Pic 1- It says 1.25" dia, but the stock was closer to 1.51 inches in diameter.


Round two - The line is where i paused to let the stringy chips break.


Third try - Finish slightly worse than second try, and chips were veery long

 

[dml66]

Just thought I'd show an update here without creating a new thread. Used the ME-Consultant software for some 4140 stock I sourced. So far I've just played around with aluminum. I feel like it did a great job with the initial starting point. I could feel slight ridges in the finish. In the photo there is a layer of oil so it's a little shimmery. Round two the surface was very smooth, and you could only just see the "ridges". I almost feel like that would work for a finishing pass finish if I had better chip breakage. The third try I tried lowering the rpms just to see what would happen.

Any ideas for better chip control? Online research suggested different insert geometry. I also have a 5/8" HSS blank to start some tool grinding as well.

Pic 1- It says 1.25" dia, but the stock was closer to 1.51 inches in diameter.
View attachment 481075View attachment 481076

Round two - The line is where i paused to let the stringy chips break.
View attachment 481077View attachment 481078

Third try - Finish slightly worse than second try, and chips were veery long
View attachment 481079View attachment 481080

Just thought I'd show an update here without creating a new thread. Used the ME-Consultant software for some 4140 stock I sourced. So far I've just played around with aluminum. I feel like it did a great job with the initial starting point. I could feel slight ridges in the finish. In the photo there is a layer of oil so it's a little shimmery. Round two the surface was very smooth, and you could only just see the "ridges". I almost feel like that would work for a finishing pass finish if I had better chip breakage. The third try I tried lowering the rpms just to see what would happen.

Any ideas for better chip control? Online research suggested different insert geometry. I also have a 5/8" HSS blank to start some tool grinding as well.

Pic 1- It says 1.25" dia, but the stock was closer to 1.51 inches in diameter.
View attachment 481075View attachment 481076

Round two - The line is where i paused to let the stringy chips break.
View attachment 481077View attachment 481078

Third try - Finish slightly worse than second try, and chips were veery long
View attachment 481079View attachment 481080

That's a real nice looking finish! It's hard to know from internet images but it comes closest to 125 micro-inches on my gage.

 

[wnchstrtnfldvlle]

That's a real nice looking finish! It's hard to know from internet images but it comes closest to 125 micro-inches on my gage.

Thanks,

It's hard to know what a realistic finish looks like when all you have are videos and photos to compare to.

 

[GT-6 Racer]

Check out FSWizard on the app stores. I use the pro version. Very handy.

 

[koenbro]

Another simple calculator is on the Little Machine Shop’s website.

But I prefer to use excel.


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