Tips for sending end mills out for resharpening

Last time I sent out end mills to be resharpened it didn't go so well. Want to make sure I'm doing my part this time, so I have a few questions, and in addition to that I'd appreciate a general walkthrough of what you guys do when you send out mills to be reground.


1. If I send out severely chipped end mills to be sharpened, what will they likely look like when they're returned? Will they be broken just sharp on the periphery? Will they grind 0.1-0.2 off the LOC to create a new end?

2. When I send out end mills to be resharpened, do I need to specify what angles I need? (I sent out some aluminum specific 3FLs to a local regrind place a while ago and they came back and chattered like there was no tomorrow, and I'm assuming they were reground with generic angles instead of the factory angles).

3. Is it generally a good idea to send them back to the factory I got them from? Will they probably recognize the list/geometry and regrind them appropriately?


So basically I want some advice on what I need to do to get them back retaining their material-specific/factory angles as much as possible (does sending them to the factory ensure that?), what do I need to specify and request when I send them out, and I'm curious if I can send out severely chipped end mills and have them returned being functional (just shorter or something).

Well, I am a control freak, so take this for what it is worth:

If mills need the bottom ground off (for a chipped corner) I specify that.
If they just need resharpening, and re-coating, I specify that, as well.
If I want 5 fl Imco Power feed mills, re-purposed as round over mills, I specify that.
If I just want them to decide, & I don't do shit; Any guesses, what I will receive in return? (where is the Poop emoji??? lol)

As I said, I am a control freak, so that is how I will handle that.

If a new tool, from scratch is required, they get drawings....

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1) If you ask them to remove the damaged bottom, I would expect them too. If not, then it comes down to the shop personnel, or company policy.

2) No, I would not believe so. They should be able to match, at least, the OEM grind. (caveat: assuming they have the spec's of the OEM grind)

3) I do not; however, if you want to be assured of the mill running like new, that is a good course of action.

Just my $.02

Doug.

In my experience it's not worth it unless your cutters are particularly large and expensive, like 3/4" and up, and/or you're doing it in significant bulk quantities.

1. A reground cutter will unavoidably have a slightly different edge prep than the original, unless ground by the original manufacturer.
2. The regrind will be of different dimensions than the original. Smaller diameter means less rigid and possible lateral holder clearance issues. Shorter means you may have vertical clearance issues.
3. The regrind may have microscopic stress fractures.

As a result, the regrind will be capable of slightly less performance than the original. You can de-tune your programs to allow for it, but then you're running slower than needed when you have a new cutter, or you can accept shorter tool life on the regrind. In any case tool life of the regrind will be more unpredictable, and you'll be less productive than when using new tooling. On top of this your toolpath verification may be invalidated; if you have near misses they may become hits.

Cost of the regrinding, plus cost of handling the regrinds (sorting, filling out forms, shipping, receiving, etc. instead of being productive), plus cost of lost productivity due to the regrind's lower performance, plus the cost of risk, needs to add up to less than that of the new cutter.