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thestelster

thestelster

Ultra Member
Premium Member
Ya know...this 1" HSS endmill has been the bane of my existence! Almost everytime I've used it over the last 20 years it has caused me misery, except when using it to true up walnut. My severed tendon on my left hand was when using this; endmill pull outs, and poor finishes. Why I still have it is a mystery. Truth be told, its mostly my fault for not ensuring a rigid enough set up.

Well last night, I just wanted to side mill a steel surface. The tooth grabbed and pulled the material in, with a huge clunk everything stopped. The VFD turned off the motor due to overcurrent. (Which is a good thing.) Well then I decided to measure if still in tram.

The mill vise was twisted, nod, and cant of the head had moved too. And not by a couple thou', more like 20-40 thou'. #$%^&#$#!!

So trammed the head and vise. I hadn't checked it in a while, so it's probably a good thing.

Though, the inside of the collet and the shaft of the endmill are badly galled. And that's a $50.00 Techniks 3/4" collet!:(

Oh, well...live and learn....though as I get older, I can't remember what I learn anymore.
 

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I keep saying it HS tooling flexes and when it springs back it tends to catch, with unexpected results, your lucky it only bent and moved a few things instead of snapping and doing the rest.

Repeat after me.....

CARBIDE

Use the following mantra from now on.

"I will only use Carbide on my mill from now on, and sell/give my lesser learned machinists the HS endmills and laugh knowing that they are in for a lesson."
 
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thestelster said:
The tooth grabbed and pulled the material in
Click to expand...
What was it that moved? Did the part move in the vise? Did the vise move on the table? Did the table move (ie backlash)? Or a combination of these things?

Just curious; like to learn from other's mishaps.

Craig
 
trlvn said:
What was it that moved? Did the part move in the vise? Did the vise move on the table? Did the table move (ie backlash)? Or a combination of these things?

Just curious; like to learn from other's mishaps.

Craig
Click to expand...
I'm pretty sure the part moved in the vise. A flute of the endmill took a bite, and pulled the part inwards, where the next flute took a bigger bite, and the next flute, etc.

If you look at the part closely in the 2nd photo, you can see the first, 2nd, and 3rd flutes biting into the steel, and going deeper with each flute bite.
 
thestelster said:
I'm pretty sure the part moved in the vise. A flute of the endmill took a bite, and pulled the part inwards, where the next flute took a bigger bite, and the next flute, etc.

If you look at the part closely in the 2nd photo, you can see the first, 2nd, and 3rd flutes biting into the steel, and going deeper with each flute bite.
Click to expand...

Agreed. That's what it looks like to me too. A 3/4" end mill is a lot of torque! So much that it stalled your motor. What gear/speed/Varidrive setting was it?
 
Good that only replaceable materials were hurt…

Classic hot rolled steel pull-out. Had that happen too many times in the past.
That scale is a b**ch to hang onto. Also, the dimensional accuracy is not as good as one would think.
I now try not to forget to use either a piece of paper / emery cloth or a strip of copper between the jaws and the workpiece when machining HRS that has not been de-scaled.
 
Advantages of HS endmills is that they are a little more flexible than carbide which is an advantage if handled roughly as it is a little more difficult to chip an edge.

Disadvantage when push even on large cutters they will flex a little which is why conventional cutting is so preferred when milling, ideally if you feed a little to aggressive the endmill flexes away from the work decreasing the load on the edge, BUT.......this same characteristic can also cause a spring back increasing (greatly) the amount of cut causing a grab, which results in work moving in vise, vise moving on table, misaligning heads, breaking tools and the list goes on.

The hard part is determining did the part move first or did the endmill flex. Most cases it is endmill flex that starts the whole mess.

Yes there are other factors but following good practice these are negated.

Carbide, well doesn't flex that much, so generally when it happens it is at a direct result of operator error not tool flex.

When you've done a few (back to back) you quickly start to see the pattern.

Besides which if you are buying new tooling Carbide, it is in a similar price to HS and for the performance/life it far out performs and out lasts HS being a better value for money.

Quick note, Carbide that is used as a general all material endmill is best uncoated, application specific is coating to increase life even further.
 
Were you climb-milling or conventional? That shouldn’t happen conventional milling, but certainly can when climb milling with leadscrew backlash added to the mix. Also, depending on how it was being held in the vise, the tang at the end of your part may have sprung forward into the cutter increasing the chipload.

Some advice from cnccookbook.com regarding Weldon flat tooling in collets:
weldon shank_www.cnccookbook.com.webp
 
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