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View Full Version : I need education on a self grip cut off tool



mototed
10-09-2011, 03:57 PM
I tried the Google search with no good results. Got a cut off tool that uses GTN2 inserts. New, USA made with Hertal inserts.and no insrtuctions.
First question. The insert sides into the grove and does not snap in tightly. I put a pieice of wood in front of it and mashed it into it's slot. Is this how to install these inserts?
Question #2. What speed and feed do these guys like? Would they be happy running a littlte faster than a HSS blade?
Thanks
Ted

beckley23
10-09-2011, 04:04 PM
Put the insert firmly in the slot and let the pressure of the cut seat it. Needs rigid set-up.

Speed about 3-600 fpm. They will also handle a heavier feed rate. Coolant really helps.
Harry

Arthur.Marks
10-09-2011, 04:07 PM
Harry is right on. The only thing to watch is the center height will lower very slightly once it begins the cut and seats into the toolholder. You remove the insert with a little L shaped wrench that is normally supplied. You just wedge it out like it was a miniature crowbar. They work real well, but keep the feed fast. Once it chips, it is garbage ;)

Arthur.Marks
10-09-2011, 04:17 PM
Here's the little removal tool that came with mine. I use GTN3 size inserts.
http://i771.photobucket.com/albums/xx357/Arrak_Thumrs/Widgets/DSCN5181.jpg

beanbag
10-09-2011, 05:15 PM
I have a similar tool. I would NOT rely on cutting action to seat the insert. If your tool is a square shank, I would put the insert in the slot, hold the relief part of the insert against something almost hard, like aluminum, and tap on the back end of the shank. That should firmly seat the insert. Or else, hold the tool firmly somehow, and tap on the back side of the aluminum piece. Do not tap the insert directly.

mototed
10-09-2011, 05:34 PM
It's amazing how tough carbide inserts are, but yet so fragile.

morehelium
10-09-2011, 11:46 PM
Make sure you run these fast enough, too slow and they will chip.

You'll be surprised how fast you can run them, just keep a dribble of coolant flowing.

You'll never want to use Hss again...

Chris

Rustybolt
10-10-2011, 12:10 AM
lots of coolant.

rbertalotto
10-10-2011, 09:45 AM
Carbide = high RPMs..........

DR
10-10-2011, 01:25 PM
Unless you already have the holder and inserts, I'd recommend not going the self locking route.

It seems most manufacturers have abandoned the self locking in favor of a top clamp that's tightened with a screw. Iscar and others who highly promoted these in years past have moved on to better systems. The secondary carbide sellers still offer the self grips since they're relatively inexpensive at initial purchase, but far from inexpensive in machines running unattended when an insert comes out.

I'd guess I must have about 5 or 6 self grip holders that got trashed in the CNC's when the insert came out during a cut. Maybe only one or two of the clamp type trashed in the last ten years.

beckley23
10-10-2011, 06:25 PM
I have to agree with DP about the clamp type holder vs the self-locking. Switched to the Manchester style for the bar capacity and rigidity of the holder.
Harry

PixMan
10-10-2011, 09:02 PM
Count me among those who strongly dislike those old GTx style inserts! They either pop out or drive into the blade too deep and bend the tab. Also, they change the center height setting as they seat deeper.

I use both screw-down clamp and spring-style holders of both single-end and double-ended style inserts and have ZERO problems.

Here's the Valenite VTG double-ended blade, also sold under the Sandvik Coromant brand as N123 series. Note that the insert seats firmly against the stop.

http://img.photobucket.com/albums/v466/kenm10759/Dads%20shop/photobucket-5564-1315255740327.jpg

This is the Valenite VSG single-ended style. It has a shoulder stop along the top edge of the insert.

http://img.photobucket.com/albums/v466/kenm10759/Dads%20shop/IMG_1429-r.jpg

I've had visitors to my shop try it to see just how nicely the holders work with the insertion and removal tool, and some here have also bought one of the same systems.

The spring clamp insert systems aren't all the same, but those GTx style are among the oldest and least-reliable.