Milling thru slot in 1.5" 4140

[32chevy]

last friday I cut this slot using a 1/2" 4 flute carbide cutter running at 1200rpm. I cut at .030 increaments of the knee crank. I flooded the cutter with molydee oil. I realized I was running slow. The final width of slot needs to be .635" in 1.5" dia shaft

Today I proceeded to side mill the slot at full depth with .010" of side cut at 2000rpm and got a very nice surface finish but it was taking to long. I believe it was singing when I tried to take a larger, .o20 side cut at full depth.

So I stepped up to a 4 flute 5/8 hss endmill and milled using the bottom of endmill at .030" depth increments at 800rpm. I Used liberal amount of oil

I plan to switch back to that 1/2 endmill and finish the slot to size. I plan on endmiling the fillets/radii of the slot by plungle cutting followed by conventionally side milling the slot at full 1.5" depth. I relize that I should have used a slotting endmill from the job.

Does anyone have any comments or suggestions?

 

[Silverbullet]

I think I would have drilled thru close to size and either used a bandsaw or slitting saw and then finish milled. I imagine it took you awhile to do it. Of course I always look for the quickest and or easiest way to do the job.

 

[brino]

Hi @32chevy,

I might have drilled a hole thru the bar for the bottom of the slot, and then cut out most of the material on the vertical band-saw, then moved to the mill for finish cuts.

-brino

 

[Wreck™Wreck]

Your major concern of saving time leads me to believe that this is a quoted job, you have to make X number of parts for a set price. If it were a hobby job for yourself time would not be the major factor, fit and finish would be.

For anyone to give useful advice answer the most important question, how many parts, 1, 10, 100 or 1000? Quantity will determine the method for you.

If a hobby project for yourself then eat the time and produce the fit and finish that you require, simple as that.

 

[32chevy]

I think I would have drilled thru close to size and either used a bandsaw or slitting saw and then finish milled. I imagine it took you awhile to do it. Of course I always look for the quickest and or easiest way to do the job.

I actually centered drilled three holes but with the limited time I proceeded to just milling. I could have drilled 1/2" holes and removed the bulk of the material. I was thinking it would be quicker to just mill vs adding two more operations

 

[32chevy]

It's a one time job. I work in quality during the day and after hours I am allowed to use the manual mills/lathes. I'm very interested in machining. I am building a reciprocating hammer for my metalshaping hobby. Thanks for the replys guy

Here's some pics of the other pieces of the project. I turned an eccentric using the 3 jaw chuck last week. I had no access to a 4 jaw

 

[sanddan]

I like the mix of fab and machining. I hope you keep sharing your progress.

I also would have drilled the end hole and used the bandsaw to cut out the waist, then machined to final size. Mostly because I have the tools and every project is also an excuse to use them in addition to the end result. The longer list of tools you can use on a project, the more fun your are having.

 

[32chevy]

Thanks, definitely will keep you all updated. We have a nice doall bandsaw at work but most of the time I go to use it, I find the teeth are dull and missing. The Operators are cutting hard materials like Inconel

Here's a few more pictures. One of my English wheel- I built the frame and bought the wheels/adjuster