# Milling Hard steel, insert holder!



## StrikerDown (May 26, 2009)

precisionworks said:


> I'm sure there are soft holders in the marketplace, most likely those from China, India, Pakistan, etc. The brand name holders (Iscar, Kenna, Sandvik, Pafana, etc.) are hard, somewhere north of 40 HRc. Solid carbide end mills work well. Inserted face mills also do a nice job, especially with ceramic or cermet inserts.
> 
> The last holder I milled, using my 2" face mill, ran at 150 rpm, DOC at .050" with a medium feed (or DOC at .100" with a slow feed).




This has been an eye opener. I started off with my 2.5" face mill running slow as it will go 150RPM. The Face mill holds 4 triangle Carbide inserts, the ones I have are not coated. I have about 3/16" or so removed on one side of the holder and the inserts first points have died. I was feeding slow taking .02 depth and the little spring shaped chips are turning a beautiful blue shade. The good news is that since they are pretty small they cool pretty quick on the bare skin! 

Even at .01 and .015 the chips look like little blue springs. This is going to take a lot more time than I thought it would! :sick2:


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## gadget_lover (May 26, 2009)

I will be corrected if I'm wrong, but I don't think that you want an end mill bigger than the width of the tool holder. You are setting up an interrupted cut that will be real hard on the carbide inserts. A smaller end mill ( 3/4 inch ???) should be able to do the job better.


I could be all wet here.



Daniel


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## StrikerDown (May 26, 2009)

I was going by what Barry used above and since I do not have any carbide end mills yet I was giving it a go. A smaller diameter would wield a lower Surface feet per min speed, that might be a good thing. 

Maybe I should look for a good carbide end mill.


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## KC2IXE (May 26, 2009)

StrikerDown said:


> ...snip...Even at .01 and .015 the chips look like little blue springs. This is going to take a lot more time than I thought it would! :sick2:



Slow down the RPM, and cut DEEPER - .02 isn't a deep cut "Bury the tool"


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## StrikerDown (May 26, 2009)

KC2IXE said:


> Slow down the RPM, and cut DEEPER - .02 isn't a deep cut "Bury the tool"



I think I need a smaller diameter tool. I am at the slowest speed option on the mill. 150 RPM. I tried a .040 depth of cut and the tool would bog down with very little feed speed.


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## gadget_lover (May 26, 2009)

According to my neat little chart, that 2.5 inch 4 insert cutter should be able to go about 2 inches per minute on the feed, max speed of 200 RPM. That assumes your mill can handle it.

It's amazing how slow 2 ipm is. 10 RPM on my handwheels.

Daniel


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## precisionworks (May 26, 2009)

The last shank I cut was at 150 rpm, .100" DOC, 2" face mill with three CNMG inserts (which are nearly impossible to chip on an interrupted cut). Triangle inserts have much less support behind the cutting edge, and are much easier to chip.

At the mine repair shop, we used to run a 2", four insert face mill at 1000 to 1500 rpm ... figure out the SFPM on that. Every chip came out either blue or red, but we limited the DOC to no more than .050". Inserts were Iscar triangles with the blue-black AlTiN coating. I've never used another 2" face mill at near those speeds.


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## StrikerDown (May 26, 2009)

Will a carbide end mill work for this? 

Size?

If so what type coating/s might be beneficial?

AlTiN?

I still have .165" minimum to remove off this side and haven't started the other side.


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## StrikerDown (May 27, 2009)

Ideas anybody? 

It's seems like my current tooling isn't up to the job or I'm not using it right.

A face mill using CNMG inserts sounds expensive for this one project. 

A carbide end mill 5/8 - 3/4" is probably cheaper to buy and assuming it does not get too dull would be more useful for future use, if it is the right tool for this work?

I can try to continue with what I have, there is two points left on the current inserts and another new set after that. 

If I continue should I cut deeper and just feed real slow?


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## gadget_lover (May 27, 2009)

A carbide end mill will work for you. I'm not sure what the best coating would be. 

I think that doing as Barry said and using a deeper cut at a slower feed might do the trick. Deeper should mean that the inserts are spreading the force over a bigger area?


Daniel


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## StrikerDown (May 27, 2009)

Thanks Daniel. 

I guess I will try the deeper and slower route first. I think I will cut the shank shorter so there is less to mill off also. I tried slower and deeper feeding before and it sounded kind of harsh like the cutters were slamming into the work, it also made te mill shake! 150 RPM seems really slow compared to he speed used on aluminum.

I need to get some carbide end mills to have on hand, they cut a lot smoother if nothing else.

This is a good learning experience, this steel is way different than the cold rolled steel, aluminum and brass I have milled so far!


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## precisionworks (May 27, 2009)

> it sounded kind of harsh like the cutters were slamming into the work, it also made the mill shake!


+1

Shops call any work above Rockwell 40 "hard milling", and this job is as tough as milling AR400 plate. A solid carbide end mill, either uncoated, or coated with almost anything (AlTiN being the nicest) will do a nice job ... get the largest one you have a collet for. I buy solid carbide end mills on eBay whenever one comes up cheap, and most of my 1" tools were no more than $20 (resharp) or $30 brand new. These come & go, and you don't find those prices every day on every search, but you'll eventually have a nice selection if you keep at it.


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## cmacclel (May 27, 2009)

I picked up 4 new Iscar 3/4 solid carbide endmills with the helical flute design a couple months ago for $30 + $10 shipping. The leave an incredible finish!

Mac


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## jtsgalaxy (May 28, 2009)

I think using some Coolant may help too.


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## StrikerDown (May 28, 2009)

jtsgalaxy said:


> I think using some Coolant may help too.




I don't have a flood system but I have been squirting it with light oil.

I wonder if there is a preferred direction of attack. I have been cutting across the shaft in two passes?


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## brad72 (May 29, 2009)

Whenever I mill hard 316 stainless I always use the climb milling method and take quite large cuts. The idea behind this is that each tip will cut a fresh section of the workpiece ahead of the workhardened edge that has just been cut. If you go too slow or use conventional milling you are continually trying to cut the workharden surface and the tips will fail very quickly.

The inserts I use are like the Kyocera TNG 222 TC300 Carbide Insert in my facing head.These inserts have no chipbreaker. The results are amazing compaired with a tip with a chipbreaker. I can getting about 6 metres of cutting from one edge compaired with 500mm with the tips with chip breakers for a given job.

I also found that no coolant is best unless you can truely flood the workpiece. Each cut chip was blue but the heat travels with the chip leaving the workpiece pretty cool. Too little coolant I found caused premeture failure of the insert through fracturing.

Hope this helps.


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## wquiles (May 29, 2009)

brad72 said:


> Whenever I mill hard 316 stainless I always use the climb milling method and take quite large cuts. The idea behind this is that each tip will cut a fresh section of the workpiece ahead of the workhardened edge that has just been cut. If you go too slow or use conventional milling you are continually trying to cut the workharden surface and the tips will fail very quickly.
> 
> The inserts I use are like the Kyocera TNG 222 TC300 Carbide Insert in my facing head.These inserts have no chipbreaker. The results are amazing compaired with a tip with a chipbreaker. I can getting about 6 metres of cutting from one edge compaired with 500mm with the tips with chip breakers for a given job.
> 
> ...



Newbie here - what is the "climb milling method" and how does that differ from conventional milling?


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## Mirage_Man (May 29, 2009)

wquiles said:


> Newbie here - what is the "climb milling method" and how does that differ from conventional milling?



http://en.wikipedia.org/wiki/Milling_cutter#Conventional_milling_versus_climb_milling


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## wquiles (May 29, 2009)

Gotcha - thanks Brian 

Will


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## StrikerDown (May 29, 2009)

Brad72, Brian,

This Both of these posts might explain a lot of what I have been observing. I didn't realize that there are times when climb cutting was appropriate.

It seems that when you push to the edge of your capabilities all the little things really add up and make things more difficult than they have to be.

I still wonder about the mill stalling when I try to take too big of a bite. I have heard that Fenner drive belts don't do well on really small radius pulleys, which is where I'm at when turning 150 RPM. Do you think I would be better off to go up to the next larger sheave on the motor, 250 RPM, or should I put the standard V belt back on and stay at 150 RPM?


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## precisionworks (May 29, 2009)

250 rpm should work OK ... at the faster rpm, try less DOC as well as faster feed.

Climb cutting is not for the faint of heart, although you see it done all the time in production shops. It works well because you are cutting a chip that gets thinner as the cutter goes through the part - conventional milling does just the opposite. Climb cutting, especially on a smaller, or older, or well worn machine, can cause the cutter to grab the part & sometimes ruin the part or the tool. Even if the part & the tool escape without damage, there's a 100% chance that the head will need retramming.

Try it & see if you like it. It works really well on machines with limited hp, because you are cutting a thinning chip. Just watch what you're doing.


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## StrikerDown (May 29, 2009)

I have been avoiding climb cuts, heard somewhere they were bad!


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## FlashKat (May 29, 2009)

Climb cutting will ruin your carbide end mill if it grabs the work piece. It is only recommended if you have a heavy duty milling machine and vise, or final light cut for a good finish. Carbide can handle heat better than pressure. Use higher RPM with coolant or a spray mister.


StrikerDown said:


> I have been avoiding climb cuts, heard somewhere they were bad!


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## gadget_lover (May 30, 2009)

Climbing cuts are considered bad because...

If you have 
1) significant backlash in your leadscrew...
and
2) You climb mill (which pulls the work into the cutter)
and
a) You have stiction
or
b) you start the cut without removing the backlash in both directions

You will end up with a situation where you are feeding at a conservative 2 ipm when all of a sudden the stiction is overcome and the table jerks as it moves to the end of the backlash in one or two directions. All of a sudden, for one revolution of the endmill, you are taking a .050 bite instead of .005, AND all the flutes try to do that at the same time. The feed is so great that the work bottoms out on the flute, meaning it will not cut. On a 1 inch, 4 flute end mill cutting .250 deep, that's a lot of metal that's suddenly in very good contact.

When that happens the vise may move, the cutter may shatter, the head may go out of tram. The work piece will almost definitely have a bad gouge where you might not have meant to put one.

Everyone climb mills sometimes. It frequently works without problems. When it does cause problems it's a real shame.

Daniel


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## KC2IXE (May 30, 2009)

FlashKat said:


> Climb cutting will ruin your carbide end mill if it grabs the work piece. It is only recommended if you have a heavy duty milling machine and vise, or final light cut for a good finish. Carbide can handle heat better than pressure. Use higher RPM with coolant or a spray mister.



It's actually a bit "simplier" and at the same time more complex

The problem in climb milling is that the tool tends to "Pull" the work and table into it. The reason "real" CNC mills work well for climb milling is that they have zero backlash ball screws, which prevents the table from being pulled

You can almost always do VERY light climb milling with ANY machine, where the definition of "Light" varies on your machine. For instance, I know if I'm running say a 1/2 end mill in aluminum taking say a .100 deep pass, and only taking say .020 off the side, and say .001/tooth, I have NO fear of climb cutting - the force in the cut isn't there to pull the table. Now, if you asked me to say take a 1 inch deep cut, say .200 off the side, at .002/tooth, no WAY am I going to climb cut - it'll suck my table up the .020-.030 backlash my mill has (I do need to set that tighter - problem is mill has to come apart to do it)

The DISADVANTAGE of ballscrews is they WILL back feed - push on the table, and it'll turn the screw, which is basically why they are NOT used on manual machines

One way to learn about climb milling - try it - start VERY light, with scrap parts, and figure out how far you can push your mill. 

I was doing a conventional cut the other day that had my ehole table shaking - made me realize that at least one set of gibs is a little too lose, but of course my mill doesn't have tapered gibs (later models of the same mill do), and to adjust the X axis gibs, you have to slide the table plus the Y axis off the mill, and flip it over on the bench, then put the whole Y axis back together, and adjust THAT - do need to do it soon however


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## StrikerDown (May 30, 2009)

Thanks to all that have posted here, This explains a lot about at least a couple issues I have had. First is this project and second it explains how I can probably get better looking results with a climb cut for the last Light pass cutting with the side of the mill. It makes sense that with conventional milling the cutter goes from zero contact to rubbing the work until it has enough pressure to actually cut, this would not lend itself to a nice finish. In a climb cut the leading edge starts cutting at the thickest part of the cut and moves into gradually thinner material down to zero and since it is moving away from the work piece it does not rub the surface and leaves a better finish. (I think I have that about right!)

I just love this forum! lovecpf

Tomorrow I think the weather and my schedule will let me get back to milling the insert holder and try this out.


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## StrikerDown (Jun 2, 2009)

Okay, The face mill I have is not the right tool for hard milling on this Mill/Drill. The suggestions above helped a little but this machine just doesn't have the rigidity and power to swing this size face mill in hard steel, a 2 inch like Barry has or softer work piece would be much better. Maybe I am just a wimp but It scares the hell out of me when the mill starts making noises and shaking with deep cuts. The climb cutting worked best but no way could I "burry The Tool" and get any where.

Next Question:

Carbide end mills, 2 or 3 or 4 flute. Is there one choice that will work for hard steel and still work okay in aluminum?

I cut the shank off to a better length using the armstrong saw... that wore out a new starrett blade, and me! Did I mention how tough this steel is!

After shortening the shank I used my only carbide end mill, (it has a drill point) to mill the end square. This is the right tool to use it cut like going through butter compared to the Face mill! Finished up with a light climb cut and it is baby butt smooth!

Another question: 
The chips really stuck to the tool, fortunately it was a short cut. It was like they were magnetized the way they stuck to the carbide. 

How do you keep the flutes clear when cutting with the full side of an end mill?

It seemed to throw the chips clear better with the climb cut.


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## precisionworks (Jun 2, 2009)

> I cut the shank off to a better length using the armstrong saw


An inexpensive chop saw, with 14" blade, is a handy shop tool. DeWalt, Milwaukee, etc., sell in the $150-$200 range. Really hard or nasty stuff is best cut with a chop saw, as any "regular blade" on a band saw or cold saw would be ruined.

http://www.tylertool.com/dewalt39.html?utm_medium=shoppingengine&utm_source=googlebase



> How do you keep the flutes clear when cutting with the full side of an end mill?


An air jet is the easiest way. My vortex air cooler provides both an air jet plus cooling air to the tool.

http://www.exair.com/en-US/Primary ...ystems/Pages/Cold Gun Aircoolant Systems.aspx


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## StrikerDown (Jun 2, 2009)

I didn't even think to use the chop saw :shakehead. I have only ever used it for steel tubing! There is always next time!

I can probably rig up an air line off of the compressor to do that. 
Does the vortex supply much pressure? 
Probably just play with a valve to get the flow right for each job.

Thanks Barry.


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## precisionworks (Jun 2, 2009)

> Does the vortex supply much pressure?


It uses line pressure ... as little as 15 psi will blow chips away, using dual Loc-Line fan nozzles. More pressure gives a greater volume of cold air.


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## gadget_lover (Jun 2, 2009)

I've been told that the 4 flute is a good choice for steel. The 4 flute has less room for chip removal. I believe that since you feed slower in steel, the chips are smaller so the chip clearance is less of an issue.

Ray, your mill should be able to handle these cuts well with a sharp carbide cutter. It is a big sucker... more HP than my mill has.  You might need to tighten the gibs, lock the Y axis and anything else that you do not have to move to get sufficient rigidity.

Danile


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## StrikerDown (Jun 3, 2009)

gadget_lover said:


> I've been told that the 4 flute is a good choice for steel. The 4 flute has less room for chip removal. I believe that since you feed slower in steel, the chips are smaller so the chip clearance is less of an issue.
> 
> Ray, your mill should be able to handle these cuts well with a sharp carbide cutter. It is a big sucker... more HP than my mill has.  You might need to tighten the gibs, lock the Y axis and anything else that you do not have to move to get sufficient rigidity.
> 
> Danile


 
Danile,

Thanks, 

I've been leaning towards the 4 flute.

A sharp cutter of what type? 

Gibs are tight.

I think a carbide end mill will work much better than my face mills, just need to find the right one. Like I said the side of my one cutter did fine on the end of the shank.

What do you think the depth of cut should be with an end mill?


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## gadget_lover (Jun 3, 2009)

One of the specifications for any drill or mill is the maximum size for drilling and face milling. It should be in the manual some where.

You will probably get good results with something like:
http://www.use-enco.com/CGI/INSRIT?PMAKA=322-6148&PMPXNO=7776352&PARTPG=INLMK32

4 Flute Centercutting TiN Coated Single End Mills Size: 3/4 Shank Diameter: 3/4 Length of Cut: 1-1/2 Overall Length: 4 Number of Flutes: 4 Type: Regular Material: Solid Carbide - Micrograin Finish/Coating: TiN $57.95 ea

Centercut means you can plunge it.
3./4 inch means you should be able to run it fast enough
Carbide = super stifff.and harder than the steel you are cutting.

As to depth of cut, that would be somthing less than the depth of the teeth on the end of the mil.

Barry can give even better advice. 

Daniel


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## StrikerDown (Jun 3, 2009)

Thanks Daniel,

I have a bid in on a 3/4" end mill on eBay. It is a resharp and the coating is black, it does not say what the coating is and I am not sure if it even matters with a resharp where the coating is ground off the cutting edge. 

Before I figured out that the cheap chinese tooling was a waste of time I bought one of those 20 piece end mill sets in HSS... Just another example of why it is best to spend more to start with and pay less in the long run. The HSS has worked fine in aluminum so far but sadly I am not working with AL here!


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## KC2IXE (Jun 3, 2009)

If you're willing to only go with a 1/2" end mill

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWAX:IT&item=180363120331

(I bought one from him - very nice)

Want a 3 flure regrind?

http://cgi.ebay.com/3-4-3-Flute-Car...s=66:2|65:15|39:1|240:1318|301:0|293:1|294:50

or a new 5 flute?

http://cgi.ebay.com/NEW-3-4-CARBIDE...s=66:2|65:15|39:1|240:1318|301:0|293:1|294:50


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## StrikerDown (Jun 3, 2009)

I'll check them out, thanks.


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## precisionworks (Jun 3, 2009)

> What do you think the depth of cut should be with an end mill?


In mild steel (hot rolled, cold rolled, free machining, etc.) you can usually go .100" DOC with a moderate feed rate, or .050" with a fast feed. In harder steels or tool steels, about half the DOC. Those numbers work well for mills with an R-8 spindle. If you have a larger machine with a 40 taper spindle, DOC can be much more. For a mini-mill, something less.


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## KC2IXE (Jun 3, 2009)

I'd say more "it depends" - for instace, the other week I was milling off the side of a 1/2 plate - I took the whole 1/2" in one pass - but the RADIAL DOC was only like 1/3rd of the 1/2" end mill

Later, I was working some 7075 - .125 DOC (left another .020 for a finish pass), again, just less than 1/2 of the cutter diameter for radial engagement


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## wquiles (Jun 3, 2009)

Thank you both - very good advice on DOC for me the newbie


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## Mirage_Man (Jun 6, 2009)

I'm a little late to this party and am new to milling. However I just milled a TMX 3/4" insert holder to fit a BXA tool holder. Then I milled a couple smaller holders for a smaller lathe. I used a 1/2" carbide 4-flute center cutting end mill. It cut through both the insert holder and the tool holders like it was butter. I did however dull the very tips of the cutters on the end mill. In hindsight I should have probably invested in an indexable end mill for this purpose. Fortunately I have a really good re-sharpening shop close to me .

Here's a couple of the small holders. The TMX insert holder is already in it's holder and I didn't take any pics of that.


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## wquiles (Jun 6, 2009)

Mirage_Man said:


> I'm a little late to this party and am new to milling. However I just milled a TMX 3/4" insert holder to fit a BXA tool holder. Then I milled a couple smaller holders for a smaller lathe. I used a 1/2" carbide 4-flute center cutting end mill. It cut through both the insert holder and the tool holders like it was butter. I did however dull the very tips of the cutters on the end mill. In hindsight I should have probably invested in an indexable end mill for this purpose. Fortunately I have a really good re-sharpening shop close to me .
> 
> Here's a couple of the small holders. The TMX insert holder is already in it's holder and I didn't take any pics of that.
> 
> (snip pic)



Very nice work. It is great to see the perfect swirl marks of a spindle in proper tram :thumbsup:


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## precisionworks (Jun 6, 2009)

> I should have probably invested in an indexable end mill


+1

My solid carbide end mills are used only for special applications, and the face mill does all the hard/rough/dirty/questionable jobs. Even though I hate to kill three tips, it beats the alternative


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## wquiles (Jun 6, 2009)

Mirage_Man said:


> In hindsight I should have probably invested in an indexable end mill for this purpose ...


To be specific, something like this probably would work great for that purpose:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=170338739468

Hard to beat for about $45 "with" a pack of inserts


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## Mirage_Man (Jun 6, 2009)

wquiles said:


> To be specific, something like this probably would work great for that purpose:
> http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=170338739468
> 
> Hard to beat for about $45 "with" a pack of inserts



I looked at that exact one the other day. If another one comes up I'll probably get it.


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## wquiles (Jun 6, 2009)

Mirage_Man said:


> I looked at that exact one the other day. If another one comes up I'll probably get it.


Well, the only reason I know about that "exact" one, is because I was the one who bought it :devil:


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## StrikerDown (Jun 6, 2009)

Mirage_Man said:


> I looked at that exact one the other day. If another one comes up I'll probably get it.


 
Ditto!


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## precisionworks (Jun 6, 2009)

> the only reason I know about that "exact" one, is because I was the one who bought it


If you want to make some easy money, send it to me & I'll double what you paid:thumbsup:

That's a high dollar piece. The APKT inserts are used on the best tooling available, and sell for $8-$12 each. The end mill lists for over $200, so you bought the package for an 87% discount from list :devil:


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## Mirage_Man (Jun 6, 2009)

precisionworks said:


> If you want to make some easy money, send it to me & I'll double what you paid:thumbsup:
> 
> That's a high dollar piece. The APKT inserts are used on the best tooling available, and sell for $8-$12 each. The end mill lists for over $200, so you bought the package for an 87% discount from list :devil:



I knew I should have bought it when I saw it.


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## wquiles (Jun 6, 2009)

precisionworks said:


> If you want to make some easy money, send it to me & I'll double what you paid:thumbsup:
> 
> That's a high dollar piece. The APKT inserts are used on the best tooling available, and sell for $8-$12 each. The end mill lists for over $200, so you bought the package for an 87% discount from list :devil:



I had no idea it was worth that much. I guess I got lucky this time.


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## StrikerDown (Jun 6, 2009)

At least we didn't get into a bidding war. Nice score Will! :twothumbs:twothumbs


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## wquiles (Jun 6, 2009)

It just came in the mail today - looks exactly like in the picture (although bigger in person than in the picture!) - everything is brand new and with a total of 10 brand new inserts, the insert tool, and boxes. I just left positive feedback for the seller


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## StrikerDown (Jun 7, 2009)

It's not the only thing you have received lately that is bigger that it looked in the pictures! :nana:


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