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Cowboy4
12-28-2007, 04:07 PM
Does the wide span between 70 and 200 RPMs cause any machining issues for the 4003G lathe? :confused:
The very limited experience I've had was on an Enco that gave about three options between 70 and 200. Are there specific applications (other than avoiding chatter) where say 100-175 RPMs would be optimum?

Like many here, I'm looking to get a machine of my own and all the information I can get is greatly appreciated.

Thanks

MColeman
12-28-2007, 05:12 PM
Does the wide span between 70 and 200 RPMs cause any machining issues for the 4003G lathe? :confused:
The very limited experience I've had was on an Enco that gave about three options between 70 and 200. Are there specific applications (other than avoiding chatter) where say 100-175 RPMs would be optimum?

Like many here, I'm looking to get a machine of my own and all the information I can get is greatly appreciated.

Thanks
No. My slowest speed is 75 and the next one is 260 and there's no problem at all. I thread at 260. I don't think speed is the primary cause of chatter, especially if you're speaking of reaming a chamber.

If you do get chatter in a reamer the best way to get it out is to used waxed paper. Take some small squares of waxed paper, about 2x2 inches, wrap it around the reamer and make certain the neck/shoulder area of the reamer is covered going back on the reamer. Run the reamer into the chamber and turn the chuck by hand while feeding the reamer into the chamber. About 3-4 pieces of waxed paper will clean up the chatter. Works like magic.

skipkh
12-28-2007, 05:47 PM
I've used the wax paper trick too - works as advertised! Nice tip :)

As for your RPM question, keep in mind that the important calculation is FPM (feet per minute) which varies with material and is also affected by coolant type used and type of cutter tool. For example, machining 414 stainless using Transultex-H as a lubricant/coolant with a HSS cutter, you are shooting for around 100FPM, which on a 1" diameter piece amounts to around 350RPM. As a matter of experience, I tend to use around 200RPM for chambering in stainless, and about 55RPM for threading stainless.

On the lathe you mentioned - 70 should be good for threading, and 200 will be about right for chambering.

Good luck!

skipkh
12-28-2007, 07:08 PM
Hey Mickey,

Not meaning to question you - especially considering YOUR well documented credentials! But... did you make a typo error? 260RPM for threading??!!! I was always taught to use the slowest speed possible for threading - I can't imagine threading at that speed. But then again, it wouldn't be a stretch to admit you probably know much more about this than the rest of us :) Do you really thread at that speed or did you mean 260 for chambering?

Chisolm
12-28-2007, 10:15 PM
Hey Mickey,

Not meaning to question you - especially considering YOUR well documented credentials! But... did you make a typo error? 260RPM for threading??!!! I was always taught to use the slowest speed possible for threading - I can't imagine threading at that speed. But then again, it wouldn't be a stretch to admit you probably know much more about this than the rest of us :) Do you really thread at that speed or did you mean 260 for chambering?

Skip
I am just a novice at threading with a lathe but if I am using a high speed insert for threading I generally thread at either 220 or 270 dependent on what it is I am threading. You just have to get the rhythm, it isn't very difficult.
James

MColeman
12-29-2007, 08:33 AM
Hey Mickey,

Not meaning to question you - especially considering YOUR well documented credentials! But... did you make a typo error? 260RPM for threading??!!! I was always taught to use the slowest speed possible for threading - I can't imagine threading at that speed. But then again, it wouldn't be a stretch to admit you probably know much more about this than the rest of us :) Do you really thread at that speed or did you mean 260 for chambering?
I do both at 260. I like to cut a 'coward's trench' AKA, thread relief groove simply because it reduces the chance of me making a slip and running the insert into a shoulder and I think it looks neat. With the thread relief groove it's a simple matter to thread at 260 (or even a bit higher). Try it and you'll see that it's not at all difficult and you get a good finish.

My 'skills' are not any greater than most of the guys on here so don't elevate me to air so thin I can't catch my breath. You wouldn't believe some of the dumb stunts I've pulled and I ain't gonna tell you, either. ;)

skipkh
12-29-2007, 08:53 AM
Dammit - thought I had ya too... THIS close to getting a nice, funny "D'OH, what was I thinking" story out of one of the Seniors!

Go catch your breath, Mickey. with a releif at the end i can see how you thread at that speed - ya got a few free seconds at the end to back the bit out.

MColeman
12-29-2007, 10:46 PM
Dammit - thought I had ya too... THIS close to getting a nice, funny "D'OH, what was I thinking" story out of one of the Seniors!

Go catch your breath, Mickey. with a releif at the end i can see how you thread at that speed - ya got a few free seconds at the end to back the bit out.
Lest you get a little too cocky I can thread at 260 without a thread relief groove but don't like to do so. ;) There is no need to take any chances because I have proved beyond a shadow of doubt that I can screw up the simplest chore......more than once, too.