Using long reach end mills

I believe you would want to look at extended neck, if searching eBay you need to check the box include description when looking under end mills. All those listed below the shank is the same size or smaller than the cutting end, probably want a 3Fl or 4Fl which should have less chatter. Carbide will be stiffer.
Some examples:
https://www.ebay.com/itm/Harvey-Too...1-4-x3-8-x1-4-3FL-Qty-3-43600964/352143694645
https://www.ebay.com/itm/Metal-Remo...3-4F-Carbide-End-Mills-QTY-2-USA/351517302764
https://www.ebay.com/itm/MICRO-100-GLR-375-4-Carb-End-Mill-3-8-In-4FL-CC-Uncoated/272781657829
https://www.ebay.com/itm/WIDIA-HANI...-Mill-3-8-Dia-1-1-2-Cut-G3830867/272817321308
https://www.ebay.com/itm/WIDIA-HANITA-TM4V0510004S-Sq-End-Mill-3-8-Dia-7-8-Cut-G3829981/282621799529
 
Have you considered taking a standard diameter end mill and reducing the shank yourself. I've done it on HSS end mills on several occasions. I fixture the end mill in a spin indexer, then put the spin indexer on the magnetic chuck of the surface grinder. Don't know if it will work for a carbide end mill, but it's a simple straight forward procedure on a HSS one.
 
Don't go with the reduced shank end mill. That will snap off in a heart beat!

Do what projectnut is saying, take a extended reach end mill and just grind down a few thousandths above the cutting flutes. Just enought the clear the part. Then chuck on it as close as you can without hitting the work piece for best results.
 
https://www.amazon.com/dp/B0080CKM26/ref=twister_B009TYM47A?_encoding=UTF8&psc=1

If you grind the flutes down for clearance, they're just as weak and prone to flexing & chatter. The solid shank, reduced neck versions are significantly more rigid. If you keep your WOC shallow, the neck doesn't rub on the pocket wall.

And get a radius end - your crank pin journal will be happier with a small fillet at the pin to counterweight point. Shafts don't like sharp corners at section changes - they snap at the high-stress points.
 
Look at Maritool for reduced shank end mills. About $70 for a 4 flute carbide end mill.

I totally disagree with 4gsr about them snapping in a heartbeat. They are much more rigid that an standard extended end mill. I started using then for deep work about 6 months ago and they are fantastic for rigidity and finish for deep work.
 
Just thinking outside the box...

Have you considered doing all the work in a lathe with a four jaw chuck? I've seen many a crank built this way.
 
Karl_T said:
Just thinking outside the box...

Have you considered doing all the work in a lathe with a four jaw chuck? I've seen many a crank built this way.
Click to expand...

I think for making a one off, that would not be a bad way to go. But, the actual reason I want my mill to it is merely to test my 4th axis. I figure if the mill can get through the quarter million lines of code that it will take to machine that crank, then I should have a pretty reliable setup.

So, the crank you see in the pictures is a totally made up, I can just get rid of the counterweights and then I can use a standard length end mill and still be able to run the 4th axis through it's paces.
 
Yep, that's going to be a complex milling job. The coding for that would be way over my pay grade.

I do think I'd consider this approach. Ruff each throw out from the right and left side. One block of code for the left, mirror for the right. repeat for the next cylinder. This code would not be horribly complex. Then clean up the last few thou and do the bearings in a lathe.


Just more outside the box suggestions. Trying to avoid all the problems too long an endmill causes.
 
Last edited:
Karl_T said:
Yep, that's going to be a complex milling job. The coding for that would be way over my pay grade.

I do think I'd consider this approach. Ruff each throw out from the right and left side. One block of code for the left, mirror for the right. repeat for the next cylinder. This code would not be horribly complex. Then clean up the last few thou and do the bearings in a lathe.


Just more outside the box suggestions. Trying to avoid all the problems too long an endmill causes.
Click to expand...

That's good insight.
 
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