# milling aluminum poor results 6x26 4 flute Tin coat



## VegasF6 (May 22, 2010)

Was practicing with the 6x26 HF mill I purchased. I had some aluminum angle, probably 6061 in a vise and a 5/8 4 flute tin coat cheap end mill in a collet. 
Consulted my feed chart and I started at full speed for the machine, 2885 RPMs. Was very unhappy with those results so I cut it in half to 1425 RPMs (or near there forget exactly) and I did have better results, but still not what i wanted. 
Rather than cutting, the end mill is melting and pushing the aluminum out of the way, even coating up the end mill some and leaving a heck of a trail behind me.
For cutting fluid I was just using a little WD-40.

So, I am about to order a couple aluminum specific 2 flute cobalt end mills from Enco, but before I do I would like some advice on what the problem, or problems may be.

Spindle speed? Feed rate? (was pretty much feeding as fast as I could turn those handles, then tried slower for a finish pass) End mill choice? Do I need to use oil/kerosene/cutting fluid?

Here is the mill I have, but this one is converted to CNC and he is just cutting the hell out of aluminum in this video:
http://www.youtube.com/watch?v=eUcxRgJgikA


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## gadget_lover (May 23, 2010)

That mill should be able to do a good job on that. 

My first thought is that you have it running in reverse. That would explain the symptoms. Watch it as it spins down to check that. Chances are the cutter is toasted. If it's dulled, you do NOT want to try using it fir any agressive cuts.

My mill is similar to yours. They work really well. 

Daniel


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## precisionworks (May 23, 2010)

> you have it running in reverse.


+1

Aluminum should cut like butter, and more rpm is better than less. Most "standard" tooling will cut aluminum, although optimized tooling does a better job - this article has good info:

http://www.moldmakingtechnology.com/articles/030702.html


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## KC2IXE (May 23, 2010)

The other thin "cheap end mill" - Just DON'T - learned that the hard way when I was starting out. Bought some of those cheap sets that ENCO et al sells - they are TiN coated turds - just don't buy them - spend the money for a couple of decent end mills


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## VegasF6 (May 23, 2010)

gadget_lover said:


> My first thought is that you have it running in reverse. That would explain the symptoms.


 
I may have exagerated it somewhat, I don't think it is actually running backwards, but I will double check on this, thanks. 


precisionworks said:


> +1
> 
> Aluminum should cut like butter, and more rpm is better than less. Most "standard" tooling will cut aluminum, although optimized tooling does a better job - this article has good info:
> 
> http://www.moldmakingtechnology.com/articles/030702.html


 
Thanks for the link to the article. It is one of the ones that got me asking the questions to begin with. 



KC2IXE said:


> The other thin "cheap end mill" - Just DON'T - learned that the hard way when I was starting out. Bought some of those cheap sets that ENCO et al sells - they are TiN coated turds - just don't buy them - spend the money for a couple of decent end mills


 
Yah, I am going to have to find a happy medium on that. I can't see paying $35 each for them, but then no point in paying for junk either. I have a 5/8 cobalt roughing mill that I tried and it sure did cut nicer. Any recomendations for decent, not super high end cutters? How about HSS, you can still get quality with it, right?

So, how important is lubrication, can I dry cut aluminum?

I am going to see if I can take a short video today and put it up somewhere, maybe you tube or my box.net account, I am just embarrased about my setup


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## precisionworks (May 23, 2010)

> Any recomendations for decent, not super high end cutters?


EBay, eBay or eBay 

Almost all my non-inserted end mills are solid carbide, purchased on eBay. Quite a few of these should work well: http://shop.ebay.com/?_from=R40&_tr...w=end+mill+aluminum&_sacat=See-All-Categories


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## VegasF6 (May 23, 2010)

eBay, I get it! Hah. So, in this case I can get one specific to aluminum. Carbide, preferrably. Cobalt?
How about a set, or a few pieces anyhow for steel. They don't all have brand names, or even if they do, it may not mean much I guess. How about something like this? They say tin, carbide, and USA but no name. 

On to much more important stuff. The good news is, yes the spindle was spinning the correct direction. However, the reversing switch is quite hinky. I tried it a few times and it broke. Into pieces. I will contact Harbor Freight about a replacement, but I don't have much hope. In the meantime, I have a project that I really really would like to get done next weekend so I need to engineer this thing to work in the meantime. It LOOKS like I could just fit any DPDT switch to reverse polarity, following for instance, this diagram. I could really use a confirmation on this though. I start having nightmares about terms like contactors and mag switches and I dunno what else. When the switch fell apart, it appeared to move a pair of contacts with round balls inside, and maybe something similar to spring steel. And it did appear burned, there had been some arcing going on inside

Alternatively, I could just jumper it for a temp solution, again, if that is safe enough? There is actually a wiring diagram on page 6 of this manual, but I am still confused.


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## darkzero (May 23, 2010)

VegasF6 said:


> the reversing switch is quite hinky. I tried it a few times and it broke. Into pieces. I will contact Harbor Freight about a replacement, but I don't have much hope.


 
Good luck with that if you don't mind the wait. You would probably be better off with replacing it with something else & better. Or check LittleMachineShop, Grizzly, LatheMaster, not sure what mill you have but many others sell mills that are similar. 

LMS actually lists replacement parts online for some of the HF machines & has them in stock (I've been there & seen with my own eyes). Grizzly lists various switches online (other search keywords might give you more results) that might work as a replacement. Bob at LM is a great person & helpful but not sure how he feels about supplying parts for HF machines over his machines. I've purchased parts from Bob but I never mentioned they were for a HF lathe.


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## darkzero (May 23, 2010)

VegasF6 said:


> eBay, I get it! Hah.


 
To add, I see you are in Vegas. I frequently go to the Crossroads of the West gun show. They also hold them in Vegas & Reno. I forget the name but there's a vendor who sells cheap tools & bits in bulk. He has a bin of end mills & other various carbide cutters. If you dig around you will find stuff that is sharp & looks to be only used a couple times or so. I always leave with nice end mills (although I don't have a mill) & solid carbide drill bits. Your choice of 6 for $20-$25 no matter the size. Much of it is name brand too. Not sure if that vendor is at the shows in NV though.


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## gadget_lover (May 23, 2010)

You can useable DPDT switch, but make sure you get one that can handle the amps. Startup amp is over 20 for a second. Mine read 28 amps when it starts with the spindle at the highest speed. 

You can also use a spst and wire it for forward only. 

Daniel


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## VegasF6 (May 23, 2010)

Awesome, I will check a few local places tomorrow for a switch like this one:
http://cgi.ebay.com/Rocker-Switch-D...tem&pt=LH_DefaultDomain_0&hash=item4cebf7aa6d

Also, Will, thanks for the tip on the gun show guy. I haven't been to a gun show in several years, and when I did it was usually Claudes, but I have hit crossroads before too. 

And, it does look like Grizzly has a part # to order the switch and housing for the 6x26 knee mill.


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## precisionworks (May 23, 2010)

> Carbide, preferrably. Cobalt?


Carbide is nice because it is less flexible than steel or cobalt & it's harder. The gibs on the mill need to be snug & the setup should be as short & rigid as possible.

Cobalt is not as hard as carbide but somewhat more forgiving if the setup isn't perfect. Lots of aluminum is still cut with cobalt & HSS tooling.



> a few pieces anyhow for steel


That's a good idea, as aluminum specific end mills don't do well with steel.


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## VegasF6 (May 24, 2010)

A wise man once told me I would need about 5 years to finish tooling. 1 year in, I am starting to think I need more time 
https://www.candlepowerforums.com/posts/2979916&postcount=17

The other funny thing is I see the same usual suspects helping out time and time again.
Barry, Will, Daniel, and KC2IXE thanks yet again. And Mac. And everyone else.


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## KC2IXE (May 24, 2010)

You're welcome.

I know why I help out:
1)I can remember being there. I'm a 'beginning pro" but long time hobiest, so I can remember
2)It makes me THINK about WHY I do what I do
3)I lean by watching what other folks post

I _Don't_ call myself a machinist, I have way way too much to learn to call myself that. I'm a hacker who usually can get what I want done the way I want. I've seen too many toolmakers and the like who make me look like a poor joke. Right now, I'm unemployed - I'd LOVE to spend 3-4 (heck sometimes 8) hours a day with one of these guys, just learning - you wouldn't even have to pay me

Great line from the story "The Secret of the Old Master" by Lucian Cary (one of the J.M. Pyne stories - republished my Guy Lutard - P.M. Pyne is losely based on Harry Pope)



> The old man shook his head. 'There is no secret' He looked at Joe Hill over his spectacles and his eyes were friendly 'Except that you have to know what nice work is, and you have to be willing to take the pains to do it. You knew that when you came here - else I wouldn't have bothered with you'


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## gadget_lover (May 24, 2010)

Like Charlie ( KC2IXE ) I share my meager knowledge just because I can. It's nice to be able to help others.

I get other benefits too. It helps put things in a different light. To explain a subject you sometimes have to research it enough to verify your understanding. 

I learn a lot by thinking about the questions that others pose. When you get 20 of us wondering about things that are "normal" for the professionals, then you also get a chance to answer those questions BEFORE you need the answers. 

Thanks for letting us help.

Daniel


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## VegasF6 (May 24, 2010)

Ordered a switch and switch box from Grizzly today. Backordered until at least July 5th 

Had no luck locally either, so ordered this one from Amazon. Hope I can make it fit, and hopefully by this weekend. Could have had this part done at a machine shop for ~50 bucks, think I am into it about $300 so far this week. With economics like this I should run for President!

Anyone see any glaring reason not to use that switch? Surprisingly I couldn't find a 20A 240V DPDT at Digikey or Mouser even. Didn't try Jameco


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## gadget_lover (May 24, 2010)

It will not last as long as a contactor. That's all. It's likely to arc a bit, but for short term that's bearable. Contactors have multiple contacts and they are heavy duty.

The biggest problem is that you want to be able to stop it immediately, and rockers are sometimes hard to hit when in a hurry.

Daniel


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## VegasF6 (May 24, 2010)

Thanks Daniel. I must admit, the contactor switch thing has me a bit confused. 
Remember though, this switch only controls the spindle direction, and is only switched before the power switch is applied, which in turn has a big old emergency stop plunger. 
With my limited experience I can't think of a single reason why I would even want to reverse the spindle, except maybe if I had a tapping head. What would be some legitimate reasons to do so?


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## KC2IXE (May 24, 2010)

Another reason that contactors are required on modern machines is safety during power failures - the contactor will "drop out" and go into stop mode, and when power comes back, the machine will not startup - where a switch MIGHT be left in the run position, and then the machine would start running with no warning


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## precisionworks (May 24, 2010)

> I couldn't find a 20A 240V DPDT


You want to look for a "NEMA manual motor starter" ... which looks like a light switch on steroids  About $20 at most electrical supply houses or online.







That one is a Leviton MS-302-S.



> things that are "normal" for the professionals


If there is such a thing  In a job shop, most every project is different. The same questions always come up - how will the part be fixtured (3-jaw, 4-jaw, 5C collet, faceplate, etc.) What's the sequence of ops (aka where does it start & where does it end). Is +/- .050" good enough, or does it need to be +/- .005". What's the best material versus what what is quickly available? 

The people I've worked with who are really good are the ones who think outside the box. 



> Could have had this part done at a machine shop for ~50 bucks, think I am into it about $300 so far


Those are the ones where you'll learn a bunch. In my shop, every new job is a prototype, meaning it takes two tries to make one good part. The third part is a piece of cake.


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## darkzero (May 25, 2010)

precisionworks said:


> You want to look for a "NEMA manual motor starter" ... which looks like a light switch on steroids  About $20 at most electrical supply houses or online.
> 
> .....
> 
> That one is a Leviton MS-302-S.


 
Although I didn't think so, these work very well. I listened to Barry's recommendation & picked one up, mine is SquareD. I'm pretty happy with it. I'm using it as a cut off rather than a "starter". The switch really is on steroids & it's stiff. This was perfect as I didn't want to spend a lot on a disconnect since one day I plan to move everything. 

SquareD offers many variations, some even have a pilot light on them. They even have ones that fit into common light switch enclosures.


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## precisionworks (May 25, 2010)

> Although I didn't think so, these work very well.


+1

Before installing a VFD on my wire brush machine, the motor was started with one - and a 3 hp, 240v, 1 ph motor draws a ton of amps when the switch contacts close (roughly 75a for about one second). Ran it that way for a few years with no problems & now use the same switch as the disconnect for the VFD.


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## gadget_lover (May 25, 2010)

VegasF6 said:


> Thanks Daniel. I must admit, the contactor switch thing has me a bit confused.
> Remember though, this switch only controls the spindle direction, and is only switched before the power switch is applied, which in turn has a big old emergency stop plunger.
> With my limited experience I can't think of a single reason why I would even want to reverse the spindle, except maybe if I had a tapping head. What would be some legitimate reasons to do so?



I looked up the wiring diagram for your mill in the HF site. I see what you are talking about. The main power and the fwd-reverse are separate. Used as you suggest, the rocker switch should last a long time.


There are a few times you might want to run in reverse. I've read of using a boring bar to cut the OUTSIDE of a tube with the normal boring bar if run in reverse. On a machine with a back gear, the reverse lets you counteract the effect of adding one gear to the drive train.

I don't recall the last time I set mine to reverse.

Daniel


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## precisionworks (May 25, 2010)

> I've read of using a boring bar to cut the OUTSIDE of a tube with the normal boring bar if run in reverse.


Here are some photos showing how the pins on a pin spanner wrench were turned down, using the mill with bar mounted "backwards" and running in reverse. Would have been faster & easier in the lathe, but needed to swing 18" to do it that way 

Centering the oversized pin 







As machining progresses





Finished pins on spanner





Since everything is done backwards, including adjusting the boring head, you may want to try this on a scrap part before turning down something of value.


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## VegasF6 (May 25, 2010)

Yah, I took the switch apart today, I have a few photos I will try and post tomorrow though. I am about 90% sure I got the wires back on the correct way, but maybe not.

Anyhow, looks like just 16 gauge wire and the switch actually says 10A at 120V. It then goes to some sort of contactor switch which finally energizes the coil. Or something. I dunno. 

Grizzly does it a little different, but I think the wiring diagram on page 46 of this document for spindle direction still applies to my case. (though they actually use a dual voltage motor)
http://cdn8.grizzly.com/manuals/g3103_m.pdf

Barry, that is an advanced technique. I am looking right at it and not even sure what you are doing. But, I know who will make my next spanner wrench


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## gadget_lover (May 26, 2010)

The technique is not that advanced. A boring head is usually used to make nice round holes that are fairly big. The cutting edge of the boring bar is on the outside of it's rotation.

But if you set it up so that the bar is barely offset from center and run it backwards, the cutting tip will spin in a small circle and act just like a lathe. The tool is reversed so that the cutting edge is on the inside of the circle. Increase the offset and it will spin in bigger circles. 

In Barry's case, he needed to reduce the diameter of some small pins BUT they were attached to some really big handles. The large flat handles bolted to his mill table easily.

It's easy to do, you just have to realize when to do it.

Daniel


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## precisionworks (May 26, 2010)

Excellent explanation, Daniel 

I've done the same type of op in a lathe (on parts that fit into a chuck) by running the spindle in reverse & moving the boring bar to the far side of the part, feeding toward center.

Can also be done by turning the boring bar upside down, running in reverse & feeding toward center from the near side of the part.

Lots of ways to skin a cat, although cat skins aren't bringing much in the market today


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## VegasF6 (May 26, 2010)

Pictures of the switch assembly:




The black square on the right houses the reverse switch, a DPDT rocker switch.





This is the back of the reversing switch before I removed the wires. I would have to say the 2 red wires are power in, I guess both hot legs.





2 of the black wires run from the reversing switch to this thing. I am calling it a contactor but I really don't know what the proper name is. They go to #3/4 and the symbol on the right, which I am thinking means motor or load?





And finally this is the back of the reversing switch. The 2 red wires are connected to the center terminals, and the black wires are actually crimped together and use the 4 end terminals. If I got them back on right they would be one pair on the left leg of terminal 1 and the right leg of terminal 3, and the other pair of course opposite that so the wires cross in an X pattern.


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## 65535 (May 26, 2010)

The red unit LOOKS to me to be a 3PH contactor with the far right lead being the trigger. If it is a 3PH unit then the DPDT switch switches two poles to reverse the motor.


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## VegasF6 (May 26, 2010)

I dunno about that I do know it is a single phase motor. 
As I mentioned, the Grizzly manual shows some better photos:
http://cdn8.grizzly.com/manuals/g3103_m.pdf
Pages 43 and 44.

The photo for Grizzly actually shows the Kedu JD2 relay, but mine as you can see has the Kedu JD3. Now that I look at the specs provided I see that you are correct. The JD2 is a single phase relay and JD3 is 3 phase. How odd. But then, it also shows the JD3 as having screw terminals and the JD2 as having spades. But, mine clearly has the spades so I don't even begin to understand that either. 

I also found the manufactures page for the switch, Kedu HY12. I tried nearly every electrical supply house, motor house etc in Las Vegas today and all but one doesn't carry any sort of rocker switch DPDT of much any size or current rating. Grainger does have one for me I will get it tomorrow, but it is 4/10s of an inch longer than the Kedu one I have. It will take some inovative mounting and some trimming that I didn't want to do, but oh well.


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## 65535 (May 27, 2010)

Well, MIC (made in china) doesn't make sense to me usually.


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## VegasF6 (Jun 2, 2010)

FYI, got a switch in, DPST for now, so no reverse. But, I was able to get my project done on time, a hub I needed for my sand rail asap. I have another switch on order from eBay so eventually I will restore reverse functions.
Yay.


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## HarryN (Jun 2, 2010)

Hi - I have done just enough milling to be dangerous, but I do have a suggestion for the new machinist - don't bother with 6061. It is a pain to get it to come our right. For a beginner like me, it is sort of like trying to make a smooth edge on bubble gum.

Gadget lover showed me some nice lead filled alloys (I think 5000 series) that make really nice surfaces easily, and the much harder 7050 and 7075 are a joy as well. Those alloys are so much easier to work with that you will be spoiled by the bad habbits you can get away with - perfect for the hobbiest.


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## precisionworks (Jun 2, 2010)

> don't bother with 6061. It is a pain to get it to come our right.


+1

6061 is consistently inconsistent 

I picked up some 4" diameter solid round stock, marked 6061-T6, and band sawed a couple or 1" thick sections. Mounted a section on the lathe & faced off one side with a high positive aluminum insert (AluPro DCGT), obtaining a near mirror finish, running about 1500 sfpm & .015 ipr.

Flipped the part to face the second side, same speed & feed, and got a dull finish with a number of pimples on the surface. Flipped the part again & refaced the first side - same near mirror finish. Go figure :sigh:


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