Help for a beginner...end mills...vises

[725franky]

I am a CAD technician, but, I am new to machining and CNC. I just bought a CNC ready Taig mill and Xylotex driver and my mill should be here tomorrow or maybe Monday. Now that the mill is on it's way I need to order tooling. But first I have a couple of questions.

Question #1 :

If I need to mill a pocket through a 3” thick piece of aluminum would I have to have an end mill with a 3” cutting edge or 1.5” cutting edge (if I milled half and flipped it over and finished). Or, could I use an end mill with a 1” cutting edge (by cutting edge I mean the length of the fluting) as long as the end mills total length was long enough to reach through?

Question #2 :

How is a toolmakers screwless vise fastened to the machine table?

Question #3 :

Where is a good place to get a toolmakers vise? Is eBay ok or should I stay away from there for tooling? I'm not looking for the most expensive vise I can get but I also don't want to end up with a piece of junk.

I'm sure I'll have more questions as I get into this but that's all for now.

Thanks for the help,

Frank

[M30]

New to CNC and machining myself, but always happy lead another blind person... so I could have it all wrong.

Originally Posted by 725franky If I need to mill a pocket through a 3” thick piece of aluminum would I have to have an end mill with a 3” cutting edge or 1.5” cutting edge (if I milled half and flipped it over and finished). Or, could I use an end mill with a 1” cutting edge (by cutting edge I mean the length of the fluting) as long as the end mills total length was long enough to reach through?

I'm learning there are trade-off for everything. Shorter tools will be more rigid in the holder and result in tighter tolerances and allows cutting harder materials faster. Generally, it seems you should go with the shortest that makes sense for your type of work.

The length of cut (or cutting edge as you put it) does not have to be as long as the depth of your pocket. You just have to be careful you don't try to cut using the bare shank. You can use a cutting length less than the total depth of your pocket if your overall tool length allows enough protruding to break through.

Now, I'm sure there is some rule of thumb about how much of the shank should be in the holder, but I don't have that knowledge yet.

Hope this helps, I have no clue about screwless vises. The only stuff I have uses a t-nut to fix the vise to the table.

[Skeeterd5150]

Answer 1 : I always use the shortest end mill I can get away with. Deflection always increases with length. As long as the overall length of the EM is 3" then you can pocket the part in one operation. That being said you can not put a finishing pass in the pocket unless thelength of cutis 3" +. I guess you could do multiple finishing passes and get away with a quality cut. If you LOC is 1.5 then you will have to do 2 finishing passes.

Question 2: I have never used those but I imagine there is a counterbored hole like the kurt vices in it. If not you could probally use hold downs on the lip of the vice or on top.

[725franky]

Thanks for the replies!

That was kind of what I was thinking; that it would be possible to use an End Mill with less cutting edge than the pocket depth just couldn't do a full finish pass.

About a vise: what would you guys recommend? I was asking about the screwless tool makers vise because that is what was suggested to me by the person I purchased my mill from. Should I look for a different kind instead? I'm just trying to get as much input as possible before I buy something and have it not perform or not meet my needs.

Thanks,

Frank

[rustamd]

this picture i found on google images showes one held on with two toe clamps:

http://members.cox.net/todd-f/Millin...urrentMill.jpg

3. http://littlemachineshop.com
www.use-enco.com
www.grizzly.com

[mrk]

Originally Posted by 725franky Question #1 : If I need to mill a pocket through a 3” thick piece of aluminum would I have to have an end mill with a 3” cutting edge or 1.5” cutting edge (if I milled half and flipped it over and finished). Or, could I use an end mill with a 1” cutting edge (by cutting edge I mean the length of the fluting) as long as the end mills total length was long enough to reach through?

Milling half from one side then half from the other works but you will probably see a line. I rough half from each side then my finish pass is all from the second side using a tool with 3" of flutes (.5" two flute EM). This tool removes the last .01" of material.

If you are milling a deep pocket make sure that you have a good radius on the corners so the tool can profile the pocket without stopping. If the tool stops moving in the corners of the pocket you will have chatter problems especially with the long tools. (i.e. .5" tool with .25" radius corner is very bad). If you can make the corners more relaxed the flex will create less finish problems.

Good luck

[725franky]

Thanks for the suggestions!


The only problem with milling the whole finish pass with a 1/2" EM is that my largest collet is a 3/8". And the longest cut EM I found in 3/8" is a 1.75" Length of cut. So I would need to have either a 3/8" shank 1/2" EM with a 3" of fluting (well, I will really only need 2.75" length of cut) or a 3/8" EM with 2.75"-3" of fluting.

Anyone know where I could get an endmill like that?

Thanks again,

Frank

[M30]

Check mcmaster.com. That place is awesome.

[under-dog]

Screwless toolmakers vise.

I have one for my taig: same setup it seems as yours.

I bought it off ebay. I forget its actual spec size but I can check that when I get home. I have been happy with it


I came up with a mount system so that I could remove it and remount it reasonably square without much fidgeting. When I say reasonably, I mean for my purposes I dont bother tramming it absolutely square. I am not working on prefinished parts where this is critical. I make sculpted pieced from raw stock so I just make the stock a bit oversize.


The way it is mounted:

The vise has grooves around it to mount with clamps. What I did was make a 1/2" plate that mounts to the mill bed with two t-nuts . This as I said is allows the plate to be reasonably squared to the mill table by the bolts for the t-nuts. This plate has four 1/4-20 holes with the edges of the hole at the with of the vise and squared to the t-nut holes in the plate. I uses 1/4-20 button head cap screws to mount the vise with these holes.

The vise always stays on the plate and if I want to remove it I just undo the two t-nuts


I will take a picture if needed as my description may be somewhat confusing

[under-dog]

I made a quick SW fil on it.

I mount with the screw to tighten the jaw outward for obviose reasons.
The way my jpeg shows this is opposite. But you will get the gist of it I hope

[725franky]

That looks like it would work well. Thanks for the idea!
I did end up buying a 3" toolmakers screwless vise like that.

Frank

[725franky]

I did go and check out mcmaster.com and they do have a ton of stuff! However on most of their EM's they seemed to be a little bit pricey from what I've seen elsewhere (mscdirect.com).

So, if you don't need something special, where is the best place to get EM's?

Thanks,

Frank