SB 9 vs. samll aluminum parts

shorton · Jan 29, 2014

I bought a nice SB 9" UMD and it's on the way. Now, learning (late obviously) it won't go very fast spindle speed wise. I need the lathe to make small aluminum parts. Typically .25 to .75 inches in diameter.

So as I understand it (now, again late) the aluminum stock I'd use should have a cutting speed of 500fpm with HSS. So on a .5" alu part I'd need 3800 RPM. The old SB catalog says my lathe's max RPM is 1365, no where near the 3800.

How bad is it going to be with the slow spindle? Sell it and go back to 7x16 @ 2000rpm brushless DC?

Finegrain · Jan 29, 2014

I make lots of ~1" Al parts at 1600 RPM and slower. The FPM figures you see for Al are optimized, but it cuts fine at lower and even much lower FPM's. It just takes longer

.

Regards.

Mike

mjk · Jan 29, 2014

unless your using the lathe in a production you'll be fine.

aluminum is forgiving and will turn fine at a slower speed

optimal conditions are great for crunching numbers for what you think you can do, adjusting your feed to give a good result by what you see and hear the lathe doing is what gets the part done

another Mike

shorton · Jan 29, 2014

Not production. Mostly high school kids making small bushings, motor couplers, etc.

I'd like to use insert (HSS) tooling. Any recommendations for inserts in these conditions?

sealark37 · Jan 29, 2014

My SB9 handles small Al parts quite well, using HSS and TT carbide inserts. I don't go anywhere near the top spindle speeds available. Pay attention to tool position, sharpness, and height. Remember, it's the machinist that determines finish results, not the tools. Regards, Clark

shorton · Jan 29, 2014

sealark37 said:
Remember, it's the machinist that determines finish results, not the tools. Regards, Clark

Yeah, but having the feeds and speeds right is what I figured the real machinst would whack me on the head for 1st LOL. And every other thing I've read said not to use carbide at these low speeds. <confused>.

SteveM · Jan 29, 2014

There are polished inserts for use with AL. Helps prevent the dreaded "chip weld".

Our own ExKenna sells them. Send him a message.

Steve

starbolin · Jan 29, 2014

shorton said:
Yeah, but having the feeds and speeds right is what I figured the real machinst would whack me on the head for 1st LOL. And every other thing I've read said not to use carbide at these low speeds. <confused>.

Yes, but...

I wouldn't say carbide doesn't work at low speeds. It's more that you don't see any savings over HSS and you don't see the advantages you get by running the chip hot. Carbide also doesn't like cheap headstock bearings. On the other hand, a polished carbide insert with a proper cut for aluminum still gives very nice finished on AL.

As to spindle speed; 1K vs 2K spindle is really just some arbitrary numbers for AL. A more efficient spindle speed for 1/4" aluminum would be something above 5K. Then you are talking machines whose headstock bearing cost more than a whole SB9. (I'm being a little bit an extremist.) If you want to run 'proper' SFM on AL then look for a chucker or a second ops machine but they are going to most likely be multiples of what you paid for the SB9.

shorton · Jan 29, 2014

starbolin said:
Yes, but...

I wouldn't say carbide doesn't work at low speeds. It's more that you don't see any savings over HSS and you don't see the advantages you get by running the chip hot. Carbide also doesn't like cheap headstock bearings. On the other hand, a polished carbide insert with a proper cut for aluminum still gives very nice finished on AL.

As to spindle speed; 1K vs 2K spindle is really just some arbitrary numbers for AL. A more efficient spindle speed for 1/4" aluminum would be something above 5K. Then you are talking machines whose headstock bearing cost more than a whole SB9. (I'm being a little bit an extremist.) If you want to run 'proper' SFM on AL then look for a chucker or a second ops machine but they are going to most likely be multiples of what you paid for the SB9.

Its not that I want to run "proper", I can't as I understand it, and you double how far I can't do it. What I need to know if I should be trying to sell this machine I just bought and is in route on a truck somewhere, or if it will work well on small diameter alu.

MetalCarnage · Jan 29, 2014

"Proper" is an elusive term at best and in this case it depends on how you present the materials to the students. Not only do you have to consider the "proper" speed/feeds for a given material a good machinist also takes in to account the machine being used to work on it. "In the case of an old SB, these are the numbers to use because...." and "Now on more modern machines we can use these numbers because..."

A "good" machinist will be able to adjust his procedures to fit both the materials and the equipment.

FYI - From a '40s - early '50s copy of How to Run a Lathe

-Ron

SBLatheman · Jan 29, 2014

shorton said:
Its not that I want to run "proper", I can't as I understand it, and you double how far I can't do it. What I need to know if I should be trying to sell this machine I just bought and is in route on a truck somewhere, or if it will work well on small diameter alu.

It will work just fine.
Ted

paulsomlo · Jan 29, 2014

Here's a well respected maker of hss insert tooling: Arthur Warner Co. | Specialists in High Speed Steel
Made in USA, as well.

Paul

mjk · Jan 30, 2014

I'll 2nd Arthur Warner hss inserts
Allows an older machine with a slower spindle to take advantage of indexable hss inserts that are ready to use right out of the box.
Their customer service was great the few times I've called them

Conrad Hoffman · Jan 30, 2014

I've been making small aluminum parts on a 1947 Logan that's very similar to your SB for many years. Learn to grind HSS and you'll get great results. Use a tuna can, acid brush and some light cutting oil like Monroe Cool Tool II. I've got some info geared to small lathes on my site at Messy Basement Website Main Index Page

I also use some insert and some brazed tooling with no problem at slow speeds, but well maintained HSS is cheap and can be instantly customized to what you need.

One other hint. Everybody seems to use 6061 for everything. It works fine but makes stringy chips that can be hard to break. Not as safe for students. Try 2011. I much prefer that as the chips will come off as chips.

shorton · Jan 30, 2014

Conrad Hoffman said:
One other hint. Everybody seems to use 6061 for everything. It works fine but makes stringy chips that can be hard to break. Not as safe for students. Try 2011. I much prefer that as the chips will come off as chips.

Thanks Conrad. We don't get to pick their materials. They come in a kit from their robotics competition program. They are required to use what comes in the kit, although I doubt any college student judge would know the difference.

For my own use, I'll try to remember to see if my supplier has any of that I can play with.

edkolt · Jan 30, 2014

I turn a lot of small aluminum parts. Use HSS and WD40 as the lube. Works well.

Ed S

shorton · Jan 30, 2014

edkolt said:
I turn a lot of small aluminum parts. Use HSS and WD40 as the lube. Works well.

Ed S

for clarity, do you mean you do it at these slow speeds of the SB9?

rbent · Jan 30, 2014

If you want inserts, the polished aluminum ones exkenna sells at latheinserts.com are excellent. I ran a fair amount of aluminum stuff on a 14.5" SB with them and had great success.

Conrad Hoffman · Jan 30, 2014

WD-40 works too, fast or slow, and you can squirt it right where needed. Whatever you use, don't turn dry, especially with some of the gummy aluminums. IMO, a real oil will work best, especially for tapping. If you turn dry, metal will weld to the tool tip and the surface finish will be lousy. Especially use a generous amount of lube/coolant/wet stuff when parting off.

QuickChange · Jan 31, 2014

mjk said:
I'll 2nd Arthur Warner hss inserts
Allows an older machine with a slower spindle to take advantage of indexable hss inserts that are ready to use right out of the box.
Their customer service was great the few times I've called them

I 2nd that. I have had good results with AW's HSS tools/inserts on my SB9, and have found their customer service folks to be great as well. I love how easily one can sharpen the inserts. You don't need to do this very often (at least in my situation), as you have three "fresh" cutting edges for use before the insert requires sharpening. I'm thinking about purchasing one of their threading tools (probably their 3/8" size offering) for use on my SB9. My lathe has an AXA Phase II (wedge style) quick change on it. Anyone care to comment on AW's threading tools?

SB 9 vs. samll aluminum parts

Plastic

Diamond

Titanium

Plastic

Stainless

Plastic

Diamond

Stainless

Plastic

Stainless

Titanium

Stainless

Titanium

Diamond

Plastic

Hot Rolled

Plastic

Stainless

Diamond

Aluminum

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