Mill Tips and Tricks

[SledGeek]

If you are on and off with the 4th axis alot ..........sub plate and keyways, perpendicular to the table slots...fixed work offset. Or put another key in the table

[KMartin]

We use our edge finder to pick up Z offset .

[Chris Rizzo]

What Bob says up there. (Must be a pacific northwest trick)

 

For setting tools, I much prefer .500 gauge pins. There is only one tangent point touching the table and tool. The lightest of pressure and the pin will either roll under or no. You can set to .0001 with no problem, big or small tools. Eliminates the flat surface of a 123 block and the whetted friction, or the block riding up on a nic on the table or chip.

 

But then again how some Haas spindles grow, might as well use a pine 2 x 4 for settting tools

[Rotary Ninja]

But then again how some Haas spindles grow, might as well use a pine 2 x 4 for settting tools

 

I have a piece of Hickory I use. Much more stable than the pine. Plus the coolant doesn't swell the wood so badly

 

Stress Relieving Techniques:

Never beat your part down on the first operation. Beating a piece of raw stock flat onto your parallels will stress it. In other words, if the material is bowed and you beat it flat then machine it, when it comes out of the vise it is going to bow back to its original shape. So the nice flat surface you just machined is now bowed. And from then on it is only going to get worse through the remaining operations. Actually, if you rough most of the material off, then release the vise and lightly re-tighten you will remove any stress you have created with the machining process. I do this a lot.

 

In theory, the best possible way to machine almost any part would be to machine it floating in thin air - or "free state". If that were possible you wouldn't add any stress from workholding. And the stress from machining would be removed with each subsequent pass. So to get as close to this "free state" as possible only tighten your vise as much as you need to to keep the part from flying out. This takes a bit of learning through trial and error (experience) and lots of parts flung about inside your machine. But I have ran a 2" face mill across a part that I have tightened with only slightly more than the weight of the vise handle because that is what I had to do. I brought the inspector over to show him this so I could watch him freak out

[The_kid]

I worked at a shop that did a lot of Ti investment castings thin wall difficult to machine complex geometry. we used set able "r" points numbers given off cmm report then spray the part with a mold release agent and bondo the part into the fixture pressing into the reference points and very lightly clamping it. suprizing how rigid this makes it. yes the dowel pin is a pacific Northwest thing. I've done this in every shop i've worked in.

[mkd]

I worked at a shop that did a lot of Ti investment castings thin wall difficult to machine complex geometry. we used set able "r" points numbers given off cmm report then spray the part with a mold release agent and bondo the part into the fixture pressing into the reference points and very lightly clamping it. suprizing how rigid this makes it. yes the dowel pin is a pacific Northwest thing. I've done this in every shop i've worked in.

i always wanted to try submerging odd shaped parts in molten bismuth. since it has a low melt point.

http://www.rotometals.com/Low-Melting-Alloys-s/21.htm

[TK-32™]

Calipers are not for scribing at all.

[The_kid]

have you heard about machinist ice? i've never personally worked with it just heard it works great for holding onto small or irregular shaped parts and you can machine away the ice no problems.

[djstedman]

Cant beleive I forgot this one.. important that all new machinists learn it.. make sure if you ever need to grind aluminum.. make sure your using the aluminum magnet!

[Bob W.]

i always wanted to try submerging odd shaped parts in molten bismuth. since it has a low melt point.

http://www.rotometal...Alloys-s/21.htm

 

I had to modify a pin heat sink once and this stuff worked great. This pin heat sink was an aluminum part about 1" x 1" with .05" diameter aluminum pins protruding upward about 1", like a mini hair brush. I wrapped tape around it and filled it with the molten alloy making it solid. When done machining I put it in a pot of hot water and the alloy melted and ran out. It turned out perfect and my customer couldn't figure out how I had done it. It works really well for stabilizing thin parts and it machines like butter.

[Rotary Ninja]

^^^ That is another good one Bob. I can think of a few times this would have come in very handy. I also wanted to say my co-worker showed me how to modify our post to add your spindle speed tip. I thought I would paste the code here for anyone (like me) that doesn't know a whole lot about editing a post file.

 

peof$ #End of file for non-zero tool

pretract

if lock_codes = one & rot_on_x, pbld, n$, *sunlock, sunlockcomm, e$

rotretflg = 1

# pbld, n$, *sg28, "X0.", "Y0.", protretinc, e$

pbld, n$, *sg28, "Y0.", protretinc, e$

rotretflg = 0

if lock_codes = one & rot_on_x, pbld, n$, *slock, slockcomm, e$

comment$

if not(index), n$, *sg90, e$

n$, "S50", e$ << ============= Added Line

n$, "M30", e$

 

That should save an eye some day! Thanks

[LancoUSA]

We ended up eliminating parallels al together with a machined step jaw. The step jaw has pin holes in the face spaced 20mm apwart for a stop. A shcs holds the pin in place from behind. The top of the jaw is dovetailed to the bottom part of the jaw making the top replaceable, mostly for crashes. Or other unmentionables! We do mostly square plates here, so using these jaws works very well for us. Moving the stop left to right is nice too because of the 20mm spacing once you find one you know where the others are, within a .001"

[RaiderX]

Clean the taper of spindle and tools. chips will cause inaccuracy and chatter.

argh just had to do this for my machinist (second part is chattering, first part didnt do this must be your program) nope no changes there..scratch head.

[MoMo1108]

have you heard about machinist ice? i've never personally worked with it just heard it works great for holding onto small or irregular shaped parts and you can machine away the ice no problems.

 

I cant find any info on this machinist ice ... do you have any or a website or who makes it

[Colin Gilchrist]

I cant find any info on this machinist ice ... do you have any or a website or who makes it

 

They were probably referring to a "Freeze Plate". Here is a link to a source for one, I'm sure there are other manufacturers as well.

 

http://www.ibagna.com/pdfs/Freeze_Chuck_PDF.pdf

[Rotary Ninja]

I looked as well and couldn't find anything.

[Rotary Ninja]

Edge Finders:

After you find the edge of a part never jog up in Z while the spindle is turning. The bottom of the edge finder can grab the face of the part and you will be buying a new edge finder. I did this for years until this happened to me one day.

[The_kid]

yeah what I was talking about was similar to the ice vice only it's an adheasive powder mixed in water which freezes harder than plain water and doesn't require external chilling unit. I can't find the manufacture of this stuff but will keep looking.

[LancoUSA]

Hmmmm, something funny i just did a search for practical engineer to see if there actually was a site that would help them be practical. There is no such site, maybe this is the problem?

[Rotary Ninja]

Ahh, you don't have your engineers trained? I have another trick for you then. Go tell them that whenever they create a vertical radius in a part to make it .260" instead of .250". And a .130" instead of .125". Sometimes you may have to rub their nose in their blueprints to help them learn to stop being bad. Tell them "BAD ENGINEER!".

 

And tell them to put a nice wireframe on your models for you. They could also be asked to plan the part to fit inside standard stock dimensions and be aware you need material to hold in the vise. I am thankful our engineers are very well trained. I think there is an "Engineer Whisperer" on the Discovery Channel if you need help getting yours trained.

 

Actually I am currently working with some pretty good young engineers. But a little communication really does go a long way.

[LancoUSA]

Yes. We always try to work with our engineers. The part fitting inside a standard off the shelf stock size is sometimes hard for them to understand. We are an all metric shop, and they make their parts come out nice and even in metric. Problem is and 80mm part is over three inches! I actually enjoy working with the younger engineers the best. They seem to listen, for the most part. The older ones are in charge though. I do love working here though. I think it is one of the best places I have ever worked.

[Rotary Ninja]

On a Haas machine disable the "Tool Release" button on the controller with setting "76". I hit this once when I had the probe in the spindle and the probe fell and hit the tool setting probe. So in one button press I managed to break the probe and tool setter in my VF2

 

In my opinion that button has no business being there, especially where it is.

[LancoUSA]

Roatary, I totally agree on the Vf-2's. We have a Vf-9 that is a different story.... I wish there were a remote place to load the tools on that maching instead of climbing in and pushing the button on the head to load and unload tools for a setup.

[Bob W.]

I hit this once when I had the probe in the spindle and the probe fell and hit the tool setting probe. So in one button press I managed to break the probe and tool setter in my VF2

 

 

LOL! Now that is when you know you're having a bad day. That is when I head out for a long bike ride...

[LancoUSA]

When we had our Vf-9 installed the Haas tech actually did that right after he got the touch off probe indicated in and set up. He had a dummy tool in the spindle not the prob, lucky us.