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First time milling.. not sure what I'm doing wrong.

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Pcmaker

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#1
Ok, guys. My mill arrived yesterday.

You think my vise is a bit big for my mill? It's a 5"







I have a cut off tool that will not fit in my quick change tool post holder. It's about .011 too big. I figure it'd be a good project to shave off .006 off each side.

So, I "zeroed" the Z axes by touching the tool with a 3/8" 4 flute HSS end mill, zeroed the graduated collar, backed off a few thou, went off to the right side of the tool, went down .006 below the zero, then started milling.

As I pushed the X axis into the tool, it became harder and harder to push in. I pushed it slow going in, then I noticed that Z axis was going up and the tool isn't being flattened. Like the end mill was being "wedged" into the tool, instead of it cutting the tool flush.



 
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4ssss

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#2
Looks to me that your end mill is wiped out, because that cutoff is hard to some degree, or you ran the spindle speed too fast. A 2 flute cutter would have been better. Did you run a file over it 1st to see if it would file? If it slicked over it, it's hard, and you may get away with using a carbide end mill.
 

pontiac428

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#3
Also lock out your gib screws or travel locks, leaving the axis you are cranking to be only free motion possible. The head of that mill isn't massive enough to fix the tool on weight alone. Locking out the travel is necessary for all but the lightest work.
 

benmychree

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#4
Most all tool holders are hardened to one degree or another, otherwise to tool post screw would mush them over when clamping, I have not hardness tested them, but would guess at a hardness of mid to high 40s to low 50s Rockwell C. Yes, machineable with carbide, but not with HSS under most circumstances.
 

markba633csi

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#5
Yes this is carbide territory, or cobalt. Also, you must use some form of cutting fluid or oil
 

SSage

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#6
The PM end mills are plain jane HSS and good for mild steels like 1018. I would take a small cut at first and even up things. But limit the cut on hard steels. I would make my first (test try) pass at .002 slowly in that mystery metal, its probably hardened. That little 3/8" HSS end mill is probably deflecting and digging in deeper on one side. My 4 flute end mills from PM cut flat surfaces really well on annealed metal, I have solid carbide for hard stuff.

Use a 1/2" 2 flute if possible and make very light cuts till it evens out. Use cutting oil or coolant in a mister. You can cut deeper till the end mill complains, but that 4 flute is HSS and not the ideal tool for the job IMO. I have a light weight PM-727, I don't push it hard at all on surface passes. The short solid carbide 12 mm 2 flute slotting end mills can cut faster/deeper on those light machines.

Make sure the part is dead nuts level in the vise and always make a shallow first pass to check for low/high spots. That lets you know if your set up is good to go for a .004 pass etc. The smaller the end mill the more gentle and shallow the cuts must be. You don't want to put deflection into the end mill. I have a few things that require a 6 mm end mill for slotting, it takes time making gentle .004 cuts with HSS. Solid carbide is worth it, you can order decent ones over seas fairly cheap. DrillPro brand on bangood.com is decent, about $8 to $12 for the small solid carbide ones. I like the tungsten end mills with the grey coating, they work good.
 

brino

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#7
@Pcmaker ,

Exciting times...Congratulations on the new mill!

As above, it is likely hardened steel in your work piece.
Test it with a file to see if it cuts readily.

It does look like a job for carbide.

-brino
 

Pcmaker

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#8
Yeah, it's hardened steel definitely. I was running my file on it and it was gliding smooth. I need to invest in carbide end mills or cobalt.

Which ones are better for hardened materials? Carbide or cobalt? And what coating?
 

Mitch Alsup

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#9
Which ones are better for hardened materials? Carbide or cobalt? And what coating?
Carbide is better for hardened materials, but it comes with the necessity that the machine be sufficiently rigid, or that carbide cutting edge will simply crack and disappear.

Ask me how I know.......
 

Pcmaker

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#10
I just used an angle grinder to grind the tool down.

Do you guys keep the window on your machines? Mine has a switch where it shuts off the machine if it's on open position. It's hard to see through the plastic.
 

Mitch Alsup

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#11
My machine never came with a window.
I can see a use for it when doing interrupted cuts, where my lathe spews chips all over the shop.
I can also see a use when machining brass, bronze, and cast iron.
I just stand to the side out of the line of fire.
 

RWanke

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#12
Kinda off topic of your milling question but what tool holder are you trying to fit that parting tool holder in? Did your QCTP set not come with a parting tool holder something like this?
Screen Shot 2018-07-10 at 8.34.14 PM.png
 

TonyRV2

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#13
I just used an angle grinder to grind the tool down.

Do you guys keep the window on your machines? Mine has a switch where it shuts off the machine if it's on open position. It's hard to see through the plastic.
Remove the C clip from the top of the window's swivel post and the whole post will slide out, window and all. The switch will be in the active position with the post removed, so your good to go.
 

Pcmaker

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#14
Kinda off topic of your milling question but what tool holder are you trying to fit that parting tool holder in? Did your QCTP set not come with a parting tool holder something like this?
View attachment 271682
This one. It'll go into the tool you posted, but no matter how tight I crank the set screw, it pops out easily. So, I tried putting it into a regular tool holder, but it's too thick to go in, had to trim down a bit off the top and bottom of the picture I posted.

 

Pcmaker

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#15
Remove the C clip from the top of the window's swivel post and the whole post will slide out, window and all. The switch will be in the active position with the post removed, so your good to go.
Yeah, I just took the whole thing out.
 

markba633csi

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#16
Cobalt is kind of in the middle: not as brittle as carbide but harder than hss and can be sharpened with conventional wheels
 

benmychree

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#17
To my experience, Cobalt HSS is just that, an enhancement of HSS, a higher preforming version of HSS, it is nowhere in between HSS and carbide. One thing about it is that it is much harder and much more time consuming to grind than normal HSS alloys. One that I use is MoMax Cobalt; damn hard and tough stuff!
 

RWanke

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#18
This one. It'll go into the tool you posted, but no matter how tight I crank the set screw, it pops out easily. So, I tried putting it into a regular tool holder, but it's too thick to go in, had to trim down a bit off the top and bottom of the picture I posted.

There's your problem. That parting tool holder you are trying to mill down is meant to be used in a lantern post type tool holder. You need to take just the tool bit (the shiny HSS blade) and put it in the tool holder of the QCTP.
 

RWanke

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#19
I ran out to the garage and took a quick pic that might help. IMG_6479.JPG
 

Pcmaker

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#20
Thanks, I tried doing that, but the blade is too small for it. I'll have to buy a new one.

What do you guys think of end mills with replaceable bits? I'm thinking of getting one and just getting carbide inserts. it may be cheaper this way?

Just broke a 3/8" end mill trying to take off .005 off a mild steel square stock. Also, I added a lamp to the mill. I don't know why it doesn't come with one standard.

I also wish I bought the smaller vise. I bough the 5" one and had no idea how large it was. This thing is heavy.

20180711_063712.jpg
 
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Asm109

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#21
First step, unbolt the swivel base and place it beneath the work bench. Remount the vise directly to the table.
The next time you need the swivel will be when you sell the vise.
 

Pcmaker

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#22
I was thinking of doing that. In fact, I'll do that right now. Any tips on how to make the vise perfectly perpendicular to the table? I've just been eyeing it and I was using a dial indicator at the side of the vise, while moving the Y axis, trying to maintain 0, but having a hard time doing so.

Are you saying there's not much reason to use the swivel on the mill?
 

poplarhouse

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#23
Indicate off the inside of the fixed jaw along the X-axis travel (Y-axis if you need the vise mounted at a right angle to your photo). Snug one mounting bolt and leave the other looser so you can pivot the vise with gentle taps of a soft hammer until your indicator reads zero (or as close to zero as you want) across the full 5" travel. Check one more time after tightening both bolts. Check You Tube for vise tramming videos: a picture is worth etc. You'll get the hang of it quickly— just make sure the inside of the jaw is wiped clean before you start.
 

ttabbal

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#24
Thanks, I tried doing that, but the blade is too small for it. I'll have to buy a new one.
Get a 1/2" tall blade. They are so cheap that it usually costs more in shipping than the blade does. Use the right tool for the job.

What do you guys think of end mills with replaceable bits? I'm thinking of getting one and just getting carbide inserts. it may be cheaper this way?
Those are indexable carbide holders. Cheap carbide inserts are OK, but good ones get expensive quick. I don't own any milling cutters that use them, but do have some for my lathe. I usually use HSS if that tells you anything.

Just broke a 3/8" end mill trying to take off .005 off a mild steel square stock.
If you broke a 3/8 end mill on a .005 cut in mild steel you had speed or feed way too high, or didn't use cutting oil. Or it's not really mild steel. I have an el cheapo HSS 3/8" end mill I have used with much deeper cuts on mild steel and it's fine. Fix that first, then think about carbide. Carbide is more expensive and breaks or chips easier than HSS. If you are breaking HSS, you will absolutely break carbide. I usually run at about 1000 RPM and feed pretty slow. I'm on a bridgeport, so you might have to adjust.

You're learning, so am I. I suggest starting with HSS end mills and 6061 aluminum for some test cuts to learn feeds, speeds, and technique. It's a far more forgiving setup than what you have tried so far. Once you have that working well, then try known mild steel like 1018. Not mystery metal and certainly not tool steel. For the aluminum, I find a bit of WD40 helps prevent chip welding. No, it's not a cutting fluid, but it does help on aluminum. For steel you need something better, there are lots of choices. That reminds me, I need to get my mister set up on the mill...
 

Pcmaker

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#25
Thanks for the tips, guys.

Currently trying to find a way to mount my dial to a collet. So far, my plan is to turn a mild steel rod to fit the collet on one end, and the other end to fit one of the arms of my dial indicator.
 

Pcmaker

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#26
Ok, this is what I came up with. I made the rod that hooks the dial to the 7/16 collet. I zero one end of the vise, then move to the other and move the vise til it's zero by patting the side of the vise with a rubber hammer. . But when I move the X axis back to the starting point, the dial moves about the same amount as when I started. I'm gonna look up vise tramming on Youtube.

 

jakes_66

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#27
Be patient with tramming. It will take several tries to get it right. Your description is very typical of mine. Just keep gently tapping the vise around and tramming until it's right. You'll get it.

:)
 

homebrewed

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#28
You want a measurement tool called a dial test indicator. They usually come with a couple of mounting posts that can be held by a collet. They can easily measure sub-.001-inch. Imports are not very expensive. They don't have much range but for this purpose you don't need much. They also are handy for centering-up smaller holes.

You want the vise to pivot around the left or right vise hold-down, so loosen just one of them. Zero the DI on the still-tight side of the vise, then move the table to the other side and tap it back to indicate zero on the dial. This should get you pretty close. Re-tighten both hold down bolts before using the vise!
 

RJSakowski

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#29
The way to square your vise is to lightly tighten one side of the vise. Zero your indicator on that side and sweep across to the far side of the vise. Lightly tap that side of the vise, using the fastened opposite side as a pivot. Most of the movement will take place on the side opposite the pivot. Adjust for zero. Go back to the pivot side. You will notice that the zero has changed but not as much as the correction. Rezero and repeat. Done right, the correction will get less and less with each iteration. When you are satisfied, snug down the far side. and recheck. If nothing is shifted, tighten both sides alternately until the vise is secure.

You should be able to get the vise square with two or three iterations. If your vise came with keys for the T slots, you can run them up against the front side of the T slot and you should be close to square.
 

RWanke

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#30
You're going in the right direction. Snug down one side of the vise (just barely snug). Start at the end of the jaw (closer to the pivot point of the vise which is the bolt you just snugged). Try tapping half the distance of what your indicator is moving when you travel to the other end of the jaw. Go back to the starting end of the jaw and repeat. You'll get there eventually. If it takes more than 3-4 tries you may want to snug the pivot bolt a bit tighter. Once you get to zero, tighten both bolts and recheck.
 
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