StupidI(ish) question...

[MarineMachinist]

This is on a manual knee mill that does not have any automatic feeds...

I am maching 5639 stainless with a 5/8 Ti coated end mill (probably not the best quality) and need to mill a 18" long groove that is 3/4" deep. What spindle speed should I be running since feed rate will all be based on how slow steady I can manually feed the bed. Oh yeah... the sunofagun doesn't have any type of coolant either (I know... it's a dinosaur) I do have a squirt bottle that I will continually refill and pump pump pump away with Tricool

Frustrated,

Brad

P.S. TM1P AND TL1 are 4 weeks away from build complete, it's obviously we need to upgrade!

[Boots]

I would try 350 to 500 RPM and rough it first. Then finish cut it. Depending on the overall size of the stock it will more than likely go "PEETUNG" when you unclamp it. Warp city....if you know what I mean. So watch for that.

[MarineMachinist]

Originally Posted by Boots I would try 350 to 500 RPM and rough it first. Then finish cut it. Depending on the overall size of the stock it will more than likely go "PEETUNG" when you unclamp it. Warp city....if you know what I mean. So watch for that.

Stock is 5"Wx1.25"Hx18" long so it will still have .500 material I doubt it will warp. This is going to be a dovetailed slot for two sliding centers for gauging the trueness of worm gears. Hopefully it cuts better tomorrow.

Thanks for the advice!

Brad

[RICHARD ZASTROW]

It will warp (or spring or distort or whatever you want to call it).

Dick Z

[MarineMachinist]

Originally Posted by RICHARD ZASTROW It will warp (or spring or distort or whatever you want to call it). Dick Z

Why do you say that it will warp? I am keeping it plenty cool, and it should have plenty of material left when I am done with the slotting. I guess only time will tell on this... Now at least I have something to look forward to on this project other than completing it...

I will let you know if it does/doesn't.

[MrWild]

stainless has internal stresses. When you machine material away, the stresses cause what is left to change shape. expect bowing. A good high quality sharp tool will cause less bowing than a cheap and/or dull tool will.

[MarineMachinist]

Thanks MrWild... I read up on it after I posted that... I can just hope that it is minimal or can at least minimize it on the finish cuts. I did however determine that 365 spindle speed with constant air flow has been the best recipe for cutting this project.

[christinandavid]

No help at all with this, but I prefer the term 'relax', as you are relieving stress trapped within the material with each cut.

As the material 'relaxes', the 'stress' is gradually transferred to the machinist. Scientists have yet to fathom the mechanism by which this transfer takes place.

DP

[MarineMachinist]

Originally Posted by christinandavid No help at all with this, but I prefer the term 'relax', as you are relieving stress trapped within the material with each cut. As the material 'relaxes', the 'stress' is gradually transferred to the machinist. Scientists have yet to fathom the mechanism by which this transfer takes place. DP

LOL @ christinandavid... You are right about that... with every pass. . . Not looking forward to doing all that work, just to find out it's no good. It would help to have higher quality end mills... I seem to keep smoking them even though I feel like I am babying the hell out of these brand new Ti coated chinsese end mills...

[christinandavid]

Is there any particular reason why you don't make the part out of something more stable (not to mention free-cutting) like a nice old smelly slab of cast iron?

DP

[MarineMachinist]

Originally Posted by christinandavid Is there any particular reason why you don't make the part out of something more stable (not to mention free-cutting) like a nice old smelly slab of cast iron? DP

Problem is that I am in Okinawa Japan and EVERYTHING here corrodes. Stainless is the most suitable material, I'd use brass or aluminum, but I need to be able to attach a magnetic based dial indicator to it. It seems to be machining fairly well, but is killing my cutters... Luckily I have a pretty good stock of cheap cutters that were given to me that I have been saving for a situation like this where it doesn't really matter if they get smoked.

[H.A.S.]

Originally Posted by christinandavid No help at all with this, but I prefer the term 'relax', as you are relieving stress trapped within the material with each cut. As the material 'relaxes', the 'stress' is gradually transferred to the machinist. Scientists have yet to fathom the mechanism by which this transfer takes place. DP

Very funny and true. I hope his cutters are extremely sharp.