Grinding flats for side lock on carbide end mills

eaglemike · Mar 18, 2018

Anyone do this on a consistent basis? How would you do it?
I used to always use collets, but the last year or so I've been going to side lock holders whenever possible. Doing that and using high speed tool paths, tool life has been improved a bunch. Combined with the speed of Speedio machines, life is better.

I've been hand grinding, but there has to be a better way.
I don't currently own a surface grinder, but if that's the best way,guess I could start looking.
Thx much!

tay2daizzo8 · Mar 18, 2018

surface grinder is a good way to do it...or just order your endmills with flats on them

eaglemike · Mar 18, 2018

tay2daizzo8 said:
surface grinder is a good way to do it...or just order your endmills with flats on them

I do, whenever possible/feasible. Fairly rare to find 3/8, much less 1/4" or 3/16" with flats.

RC Mech · Mar 18, 2018

Tool and endmill grinder with a cup wheel.

cyanidekid · Mar 18, 2018

Can’t think of a reason to use a surface grinder for this, unless you are trying to register the flat to the flutes for some reason.

All you need is a divot for the setscrew, right? Air die grinder with small diamond wheel, about 10 seconds if you take your time.

Total cost of machine and tooling, 50 bucks, new.

Don’t breath the dust!!!

litlerob1 · Mar 18, 2018

Just a regular pedistal grinder, and a wheel for Carbide. As long as the flat is enough for the screw to locate, that's all you need. It takes me 10 seconds, I'm not going to take 5-10 minutes on something that works just as good in 10 seconds. Train the guys to not rotate it while grinding, just put a small mark on there, where is the Endmill possibly going to go? Normally you have -.0002" on the Endmill and +.0002 on the Holder, that means your flat needs to have less Taint than that, for it to budge.

OTOH if you have Greenies not locating the Endmill correctly, then its time for training. Locate the Tool on rotation and once the rotation is hitting, then pull it out as far as it will go then tighten it.

R

What he ^ said

guest · Mar 19, 2018

I use a 90 gun to grind whistle notches in carbide shanks all the time. Piece of cake and more secure than a flat, imo.

Bobw · Mar 19, 2018

Like most, I just blast them on a green wheel. Its not rocket science..
Even when they come with a flat, it seems I ALWAYS need to hang out another
1/4" of so, and end up grinding a flat anyways...

Now, I *guess* you could run into balance issues.. I know Maritool balances his
set screw holders with the set screw run up into a proper weldon (weldEn?) flat..

At what point that begins to matter? I have no idea.. I'm curious, but I don't
worry about it.. Does anybody know??? Educated guess says smaller diameter
would matter less than larger diameters...

What I would REALLY like to know is who is the Rocket Scientist that came up with
the set screw sizes in the set screw holders.. Some oddball metric size with an
American hex in it.. And why do they cost $5????

Finegrain · Mar 19, 2018

Bobw said:
What I would REALLY like to know is who is the Rocket Scientist that came up with
the set screw sizes in the set screw holders.. Some oddball metric size with an
American hex in it.. And why do they cost $5????

Really? I thought they were generally regular fine-thread UNF?

Regards.

Mike

Pete Deal · Mar 19, 2018

How important is it to get the width of the slot (top to bottom- axially) right so it mates reasonably well with the end of the set screw? I thought I read in one post that is important to get this right to trap it to better resist the cutter pulling out.

Bobw · Mar 19, 2018

Finegrain said:
Really? I thought they were generally regular fine-thread UNF?

Regards.

Mike

I had to go check.. 7/16-20 for a 1/2"... I had it in my head that they were an oddball.
The only thing I can see is that the end is machined flat, not a cup.....

$13 for 25 of 'em from McMaster Carr, and then machine or grind the ends flat..

So the question still is... Why are they $5 a piece??

Mtndew · Mar 19, 2018

I've been using a pedestal grinder and a green wheel for over 25 years, zero issues.
No need for a tool grinder, or a diamond wheel on a surface grinder really.

litlerob1 · Mar 19, 2018

Pete Deal said:
How important is it to get the width of the slot (top to bottom- axially) right so it mates reasonably well with the end of the set screw? I thought I read in one post that is important to get this right to trap it to better resist the cutter pulling out.

Not important. Most of the set screws I've seen are "Flat point"(not to be confused with Dog point)set screws, which have a point that is smaller than the Minor diameter of the screw. The human hand can't make an actual Flat on the shank of the Tool, but that's better. You can feel it locate when you tighten it. If you can't, go over and take a little more off.

Mark Rand · Mar 19, 2018

The ones I have screws that are spaced and have a taper that matches the taper at the end of the slot and the end of the endmill. I guess that's just coincidence???

Mtndew · Mar 19, 2018

Mark Rand said:
The ones I have screws that are spaced and have a taper that matches the taper at the end of the slot and the end of the endmill. I guess that's just coincidence???

No those are made to fit the weldon style shanks.
All you need is a hand ground flat at an angle so that the end mill can't pull out.

litlerob1 · Mar 19, 2018

The Angles are 90, it isn't a coincidence, but it doesn't matter either. For rotation security, you only need a single point of contact, inside the OD of the shank. For pull out you only need to make sure it won't.

R

DavidScott · Mar 19, 2018

Why, Dennis doesn't bother with flats for his sidelocks. He says he runs the tools hard in his Brothers with no problems. I have done this a little but have not really "tested" it with heavier cuts.

eaglemike · Mar 19, 2018

I have been running with hand job'd "flats" from a green wheel on a bench grinder. Never really had an issue. I had some concerns that "maybe someday" I would have a problem due to the end mills fretting a little. The not quite really flat surface vibrating against the point of the set screw. Since no one really seems to have an issue, I'll forge ahead pretty much as before. I will try a few of the cheap diamond cylinders used in a Dremel on smaller shank stuff and see how it goes......
Thanks for all the input!!!

aarongough · Mar 19, 2018

If you want a really nice rig for putting on flats quickly:

Tradesman DC Variable Speed Reversing Bench Grinder

They have a specially profiled wheel that does it with the correct shape quickly, and a holder that rotates into the wheel for consistent placement...

Shop Supply Guru · Mar 19, 2018

Helical makes 4 & 5 flute endmill standards with flats.

Grinding flats for side lock on carbide end mills

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