# I Milled!



## mike837go (Aug 10, 2015)

I did my first practice milling with my new G0516.

A piece of scrap-for-reuse, poorly clamped and a random (5/16") milling bit.

Still got a fairly straight cut across the steel.

Now I'm ready to build me another lathe. From scratch


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## T Bredehoft (Aug 10, 2015)

That's what it's all about. The learning curve comes in when you "engineer" your project.


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## mike837go (Aug 10, 2015)

I was being just a bit facetious. Make my own lathe? I don't have a foundry to pour the castings.... Yet.

My first official milling project is to make a copy of the output shaft of the belly mower's "transmission". It uses the rear PTO. Two shafts, a tensioner and triple-ganged belts moves the power down 14", 3" to the left and sends it forward.

The copy won't have the reduced diameter from where a previous owner neglected a bearing.


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## brino (Aug 11, 2015)

Congrats on the first cuts! 

Do be careful about poor clamping, don't damage you or the equipment.

Maybe a set of t-nuts and clamps is a good first project 

-brino


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## mike837go (Aug 11, 2015)

The machine came with 2 t-nuts. I put exhaust system studs in 'em and lined them up with holes in the "work piece" and torqued the nuts to about 20ftlbs with a wrench. There was very little chance things would get loose suddenly.

The 'poorly' side of things was that the holes I used were 6" from where I chose to mill. The 3/8" thick piece of scrap flexed away from the cutter. Passes back cut more material as the piece sprung back.

When I was trained on The Drill Press (middle and high school shop classes) proper clamping was REQUIRED. A stalled motor beats bashed hands or spinning work ANY day!

My first real project is building a replacement shaft for the transmission that gets the rear PTO power headed forward to a belly mower.

The vice that was included with the lathe/mill came with 2 more t-nuts. It has been mounted solidly and trued-up. Just waiting for the 1" round stock to show up.

All work will be done within the width of the vice's jaws. Any flexing will be within the compression of the bar and the oil between the cross slide, the carriage and the bed. Lets not forget about the flex in bed casting/mill support as well.

Daham. I used to think of machinery as solid objects with some moveable parts. This thinking of a conglomeration of _near perfect_ pieces slipping, sliding, compressing, springing back, .000000000001" backlash is hurting my head!


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## Ulma Doctor (Aug 12, 2015)

machining gets a little easier every time you do it. 
it seems like a lot of stuff to keep track of, but as you do it, things will all become second nature with some practice and study.
i wish for your continued success!


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## mike837go (Aug 13, 2015)

Second attempt at milling last night.

Success!

After pulling the bit back out of the collet. Seems you have to _REALLY_ tighten the (need the proper name for the internally threaded piece that secures the collet in the spindle).

I made the shaft my finish mower needs.













Image



__ mike837go
__ Aug 12, 2015



						PTO box output shaft
					




Now to wait for Tractor Supply to get the new belts...


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## tmarks11 (Aug 16, 2015)

mike837go said:


> After pulling the bit back out of the collet. Seems you have to _REALLY_ tighten the (*need the proper name for the internally threaded piece that secures the collet in the spindle*).


Drawbar.

Typically should be 25-30 ft lbs of torque to tighten the drawbar.


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## T Bredehoft (Aug 16, 2015)

I've started accumulating R8 tool holders, they use a setscrew to secure the end mill, don't require over torquing the drawbar.


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## tmarks11 (Aug 16, 2015)

I am a big fan of endmill holders.  Just make sure the endmills you are buying have weldon flats.  Many will argue you don't need them, but no reason not to get them if you rely on end mill holders.


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## mike837go (Aug 17, 2015)

ARRRRGGGG! Ratsafratsin off-brand second-rate imitation of a tool!

The draw-in bar pulls the whole collet holder into the quill on the G0516.

The collet holder setup on this thing is an oversized copy of a stinkin' Dremel. The part I hadn't torque-up properly was the 'retaining nut'.

More egg on the face for the n00b.

I googled how REAL milling machines are built. I saw how the draw bar tightens the collet in those.


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## tmarks11 (Aug 17, 2015)

mike837go said:


> The draw-in bar pulls the whole collet holder into the quill on the G0516.... The draw-in bar pulls the whole collet holder into the quill on the G0516.


Your post isn't real clear.

That is how all drawbars work.  The drawbar pulls the collet up into the MT3 taper inside the spindle, which forces the collet to tighten on the endmill.  Hence the name "draw bar".  The collet just about completely disappears in to the recess.

A drawbar arrangement is simplicity in itself, and a quick look at the G0516 parts makes it look just like how a Bridgeport mill works.  Although the Bridgeport is blessed with an R-8 taper instead of an MT3 taper.

MT3 taper and collet isn't a "copy of a dremel".  MT3 taper has been around a long time, and predates the R-8 taper found in newer/larger machines.

The "draw nut" on top of the drawbar is common on smaller machinery, like my Clausing 8520.     Still works the same as a drawbar with a solid top on it.  If you want a solid drawbar, you could make one one your lathe. Or make a large nut to fit the top of the drawbar and drill a pin to hold it in place. Or buy one here:
http://littlemachineshop.com/products/product_view.php?ProductID=1414&category=2

I personally hate the MT taper... my Clausing 8520 has an MT2, and the collets get stuck with some regularity... it is classified as a "self holding" taper instead of a "self releasing" taper like an R-8.

Just a note: tightening a collet into a spindle without an endmill in it will damage the collet.

Another note: you can buy an X-2 base from Little Machine Shop for the mill portion of the G0516, and gain a whole separate milling machine out of the deal.  Or sell it as a separate unit and buy a mill you like better.  Two choices:
http://littlemachineshop.com/products/product_view.php?ProductID=1765&category= (smaller)
http://littlemachineshop.com/products/product_view.php?ProductID=3677&category= (larger)


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## mike837go (Aug 18, 2015)

tmarks11, you are absolutely 100% correct about the construction of good-quality, name-brand, professional mills.

But I just bought a Grizzly G0516. And they do things 'on the cheap'.

I did a little research and looked at the pieces a little more clearly.

Firstly, the quill has a machinist taper (which one, I haven't a clue). Grizzly uses a draw-in bolt to pull the drill chuck or collet holder securely into the quill.

They supplied several 1.5" long collets of various diameters that snap into a nut and are assembled into the collet holder.

The same engineering as a dremel tool. Not the 150+ year proven system that a real mill uses.

I'll try and remember to get some pix and post 'em.

Somebody here already dealt with a similar setup: http://hobby-machinist.com/threads/what-collet-system.35866/


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## tmarks11 (Aug 18, 2015)

mike837go said:


> Firstly, the quill has a machinist taper (which one, I haven't a clue). Grizzly uses a draw-in bolt to pull the drill chuck or collet holder securely into the quill....They supplied several 1.5" long collets of various diameters that snap into a nut and are assembled into the collet holder.



It is an MT3 taper, as I said above.

A draw bar is a "draw-in bolt".  Might be fancier on some machines, but it is functionally just a long bolt... or a long stud with nuts on one end.

Initially I was thinking they had provided you with an ER20 collet holder (which a lot of people use to hold end-mills.  But 1.5" is a bit long for that size.  You said it looks like a dremel... makes me think it is a Double Angle Collet, although that seems unlikely, as that is a superior more-expensive collet design:




I doubt that a chinese manufacturer "invented" their own collet standard when there are so many to chose from already.

Regardless, you should be able to buy MT3 collets and mount them directly in the taper in your machine.  Those collets look like this:




The G0516 has been a very popular machine over the years (partly because you could harvest the milling head and add the LMS base, and sell a complete Mini-Mill to finance the purchase of a larger machine).  There is a lot of information available from owners over the year; unfortunately much of it is in Yahoo Groups which has been rendered almost useless by their shift to a cumbersome web interface.

If you are googling for info, looking for "Sieg C6 lathe" might help; that is the lathe model that the G0516 is built on.


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## mike837go (Aug 19, 2015)

Unquestionably the milling tool clamping system is a Chinese copy of a good design.

If I had remembered last night, I would have snapped a pic of the whole kit: collet holder, nut, a bunch of collets and a wrench.

I'll try and remember tonight. Thought the finish mower is back online, working better than when we bought it. And the lawns haven't been done in 3 weeks....


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## brino (Aug 19, 2015)

I had to go download the Grizzly G0516 pdf manuals to see what this was all about.
I had seen collets with draw-bars _or_ nose nuts, but not both.

http://www.grizzly.com/products/Combo-Lathe-w-Milling-Attachment/G0516

Here's what the parts manual shows:




So rather than use MT#3 collets and a simple draw-bar, they use an MT#3 to something adapter and a bunch of smaller collets with a nose nut. It probably is some known standard taper and collets, but they do not say what.

Too bad, this system is likely more limited in holding capacities than the MT#3 set Tim shows above.
I'd be tempted to throw the Grizzly supplied set in a box, and buy the MT#3 ones.

It looks like that original set of collets has a groove that should be used by an off-centre holding ring in the nut to pull the collet from the taper on extraction. The collet should be installed in the nut, before the nut/collet and put into the adapters taper. Otherwise the nut will actually push the collet off centre and possibly damage something. I saw no mention of that in the parts or owners manuals! 

One advantage of the Grizzly supplied collets; they get loosened off the work by loosening the nose nut.
Unfortunately, you still have to use a soft hammer to remove the adapter from the mill spindle.
They just moved that problem(having to pound on the end of a threaded shaft) from one place to another.

-brino


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## mike837go (Aug 19, 2015)

Dats dem alright!
'ceptin the nose nut has flutes and uses a spanner. Not the hex pictured in the parts list.

And yes, you clip the collets into the nut before screwing it on the holder. Otherwise, the pieces go way off center! First-hand experiance there.


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## tmarks11 (Aug 19, 2015)

Hmm, looking at Grizzly's site, they sell the "Quick Change" collet set, that looks like a bastardized ER32 collet set. The angle on the collets isn't quite as steep as it is on an ER set.  Guess I was wrong about the factory not "inventing their own standard".  Does your kit look like this?  The diagram in the previous post makes it look like the end that mounts into the mill is cylindrical rather than tapered.


I have an MT2-ER25 collet holder that I use with my Clausing.  Very popular accessory because you can swap out endmills faster with it than by using the drawbar and conventional spindle collets.

The nut on the ER collet is designed with an off-axis hole to make inserting the collets into the cap possible (and quick)... by design.  Putting them in the holder, and then screwing down the nut does not work, as it sounds like you discovered.



> Unfortunately, you still have to use a soft hammer to remove the adapter from the mill spindle.
> They just moved that problem(having to pound on the end of a threaded shaft) from one place to another.


The idea is that you can leave the collet holder in place, and only loosen or remove the collet nut to swap endmills... which works until you have to use a drill chuck.

The downside of the MT taper is that it is not "self releasing", and sometimes requires some good smacks to get it to pop out.  Sometimes requires quite a bit more than a "good smack".


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## brino (Aug 19, 2015)

tmarks11 said:


> that looks like a bastardized ER32 collet set



You got that right!!!!

It's not just the angle:
-those slots are only cut from one end, that means it will only compress and grip at the front edge, the tool/work will still be "tippy" in those even when tight!
-looking  at those holes near the back end, the collet is just a thin shell on all diameters; there is nothing at the back edge to grip the tool/work!

The real ER-32 type collets are split alternately from each end and are the stated internal diameter at least an inch in for the small diameters and all the way thru for the ones larger than about 3/8".
When they contract they grab for nearly the entire length.

Here's some shot I just took of a 1/8" er-32 collet:





and a 3/8" collet:





-brino


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## mike837go (Aug 20, 2015)

brino said:


> You got that right!!!!
> It's not just the angle:
> -those slots are only cut from one end, that means it will only compress and grip at the front edge, the stock/work will still be "tippy" in those even when tight!
> -looking  at those holes near the back end, the collet is just a thin shell on all diameters; there is nothing at the back edge to grip the work!
> ...snip...



That would explain why my cheep hobbyist mill has them and the professional units still use the more accurate, tried-and-true system.


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## mike837go (Aug 20, 2015)

tmarks11 said:


> Does your kit look like this?


Almost exactly! There are twice as many flutes on the nut and the lands are polished. But that's pretty much it. Add a Styrofoam storage rack and a cardboard presentation case and you've got the whole kit!


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