# Tool holder holding a "T" cut off blade



## Pcmaker (Mar 16, 2019)

So,I have this type of parting blade holder:







The problem is that I have a "T" shaped, tapered blade and it follows the side of the tool holder. It's kind of hard to see, but the blade is not perfectly vertical. The blade leans to the side a bit and I have no idea how to make it stand straight up.


----------



## darkzero (Mar 16, 2019)

You could put a piece of shim stock or feeler gauge behind the thinner part of the blade.

Or you could mill a relief on the holder.
(Pic stolen from the net)


----------



## mmcmdl (Mar 16, 2019)

You have the wrong blade . I would think it be better to purchase the correct blades for the holder vs. altering your holder .


----------



## darkzero (Mar 16, 2019)

Although many call these blades T-type the actual name is P-type. I've seen P-type blade holders that have a relief (not QCTP holders), should be fine to mill out a relief on an inexpensive China holder. But then again I don't use these blades & have never tried it.


----------



## Latinrascalrg1 (Mar 16, 2019)

Milling a relief so that the "T" shaped parting tool fits the same holder used for flat parting tools should not be a problem.


----------



## Tozguy (Mar 16, 2019)

Looks like the blade in photos above got pretty hot during the grinding.


----------



## ddickey (Mar 16, 2019)

That's a heckuva an angle. I think the blade should be ~7°. What's the angle of the holder?
That deson't look like a T or P type blade, not saying it isn't just looks different than mine.


----------



## savarin (Mar 16, 2019)

I use that holder with the "T" shaped blade.
I havnt ground a relief although I probably will.
I regularly part off stainless with no problems.
My major problem is the hex socket has worn to unusable, its L/H at the socket end and R/H at the other end and I cant find a replacement.


----------



## Pcmaker (Mar 16, 2019)

What tool holder is used with the "T" type? or "P" as someone mentioned?


----------



## Cadillac (Mar 16, 2019)

mmcmdl said:


> You have the wrong blade . I would think it be better to purchase the correct blades for the holder vs. altering your holder .


Do thy sell a qctp holder with the relief as described  I have yet to see one but admit haven't gave much of a look. I use a T style one and have no problems with it. When the tool is drawn into the holder the tool squares up to the holder because of the top and bottom surfaces of the tool. The tool shouldnt be seeing side loads so the "gap" shouldn't effect the cut. I too have seen people modify the holder by cutting a slot but I never had a problem to do so.


----------



## homebrewed (Mar 16, 2019)

The 250-107 parting blade holder is touted as a "universal" blade holder, and is claimed to be compatible with both P type and tapered cutoff blades.  For instance: this one.  Most of the images I found online weren't detailed enough to see how it can accommodate P (or "T" profile) blades.  Maybe there's a trick to installing the blades.


----------



## ddickey (Mar 16, 2019)

The FoR Inverted Parting Tool Holder
					

The FoR Inverted Parting Tool Holder. The FoR Inverted Parting Tool HolderThe  FoR Inverted Parting Tool Holder operates with the blade held in an upside Read more



					www.eccentricengineering.com.au


----------



## Nogoingback (Mar 16, 2019)

mmcmdl said:


> You have the wrong blade . I would think it be better to purchase the correct blades for the holder vs. altering your holder .




And what blade would that be?


----------



## Meta Key (Mar 16, 2019)

Pcmaker said:


> The blade leans to the side a bit and I have no idea how to make it stand straight up.



For the last 20 years I've had only one vise on my mill.  I had ordered it with a swivel base and, in all those years, I have never used the swivel.  Recently, I decided to buy an upgrade vise (GMT, 4") and ordered it without a swivel base.  Couldn't justify it based on my long history of non-use.

The _very next day_ I decided to try a P style cut off tool that has been in my toolbox for about as long.  (I've always ground my own cut-off tools.)   Mounted the blade, saw the issue you describe and immediately put the tool holder in my 20 year old vise and used the stupid swivel base for the first time ever!

The irony was hilarious and I was smiling and chuckling the entire time I cut the groove in that toolholder.

MetaKey


----------



## Pcmaker (Mar 16, 2019)

I took off the swivel base off of my vise. I can't adjust the angle with just the vise on the mill table, so I gotta put the swivel base back on. 

The tool holder is made of some pretty hardened steel. I used a 5/16" HSS endmill and I can't cut it correctly. The tool holder steel is becoming "gummy."


----------



## benmychree (Mar 16, 2019)

I have used P type and tapered blades in the same non relieved Aloris holders for probably over 40 years, I've thought about relieving the holder, but it seems to work fine as is.  I use HSS parting tools for most work, and reserve carbide for stainless and deep cut off and grooving roughouts.
That HSS tool shown has probably at least 4 times too much front clearance, which drastically weakens the tool and would cause it to wear off at the point, likely burning off and possibly causing hard spots, as stated above, 7 degrees more or less should do the job.  Radical grinding showing burning is likely to cause fine cracking at the cutting edge, "they" say.


----------



## Meta Key (Mar 16, 2019)

Yeah, the tool holder was a little tough. Not like 4130 or stainless tho. 

I used a four flute 3/16” HSS end mill and the DOC was .030” which was all that was needed to clear the blade. 




I was running at least 1000 RPM. Maybe more. Mill goes up to 3250. Didn’t think about it much so I don’t recall. 

MetaKey


----------



## benmychree (Mar 16, 2019)

Too fast for hard, unless carbide cutter.


----------



## Meta Key (Mar 16, 2019)

benmychree said:


> Too fast for hard, unless carbide cutter.



Wasn’t hard, can cut it with a file. Cut nicely  with that 3/16” HSS cutter. 

It’s an import tool holder so I’d have to designate it as mystery metal.   ;-)

MetaKey


----------



## darkzero (Mar 16, 2019)

Meta Key said:


> Wasn’t hard, can cut it with a file. Cut nicely  with that 3/16” HSS cutter.
> 
> It’s an import tool holder so I’d have to designate it as mystery metal.   ;-)
> 
> MetaKey



Yep, I've milled & turned China holders. They're not that hard. China hardened is not the same as USA hardened.


----------



## Buffalo21 (Mar 16, 2019)

darkzero said:


> Yep, I've milled & turned China holders. They're not that hard. China hardened is not the same as USA hardened.



Yeah, either hardened too little or hardened too mush, Chinese hardening can be a real crap shoot.

I bought some cobalt drill bits from Graingers, they had a rainbow hue to them, the 3/8” rolled off the table, hit he floor and shattered into hundreds of pieces. I thought that was strange, so I purposely let the 5/16” bit, roll off the table, it hit the floor and shattered.

I took a different bit from one of the other serviceman’s box, the bit caught, the chuck kept rotating about a turn and boom the spiral in the bit was gone, twisted like a Twizzler. I show it to the other guy, he said yeah, he has 3 or 4 more, that that happened to.


----------



## Buffalo21 (Mar 16, 2019)

Back to the original programming, I have 3 of the cut off tools holders, I never been able to get them to cut worthy a damn. I finally went to a carbide insert style cutter and moved on.


----------



## Pcmaker (Mar 16, 2019)

Managed to get it done with a 3/8" cobalt endmill. Quite a bit of burrs, though. Do you guys normally an endmill over the burrs or just use a file?


----------



## porthos (Mar 16, 2019)

i use a aloris AXA  tool holder. the AXA7 holder is made for  this type of cut off tool that is wider at the top.


----------



## Tozguy (Mar 17, 2019)

It is file for me.


----------



## Janderso (Mar 17, 2019)

Interesting subject. My only experience is with the P type blade using a BXA Phase 2 holder in my old 13" South Bend vs. the Clausing Colchester 15 (CXA Aloris #7).
The SB chattered something fierce. The Clausing cut through with no chatter or whining.
Rigidity is key.
I never thought about cutting a relief, don't need it.
Let us know how how it goes with the holder cut PCmaker.


----------



## Pcmaker (Mar 17, 2019)

It's working fine now. I cut the relief and it's straight enough. The problem is that even though there's a relief, the entire blade is tapered. It has a "T" at the top, and the bottom is tapered. The relief helps a lot. Just had to straighten the blade vertically, and the side of the blade doesn't even touch the inside wall of the tool holder because of the taper. Just had to put a lot of pressure on the top retaining block, forcing down on the top of the blade to keep it straight. So far, i've been parting with no issues. I've even been using the auto feed on the cross slide and works great.


----------



## royesses (Mar 17, 2019)

I milled a relief on mine from LMS. I used a carbide end mill as the hss end mill I tried first just burned up. The LMS holders are hardened.
The holder still holds the non T type properly.

Roy


----------



## pontiac428 (Mar 19, 2019)

Question for those of you who have modified your cutoff tool holders for P-type blades:  Do they perform better after the modification?

I use P-blades in an unmodified holder.  Worst thing that I get is an angled cut, presumably from deflection.  I set blades to the depth to center, never more, for each and every parting job.  I'd love to get a square cut out of a squarely positioned tool.  Any other improvements would be welcome.


----------



## Pcmaker (Mar 19, 2019)

I couldn't even part before I modified the holder.


----------



## royesses (Mar 20, 2019)

pontiac428 said:


> Question for those of you who have modified your cutoff tool holders for P-type blades:  Do they perform better after the modification?
> 
> I use P-blades in an unmodified holder.  Worst thing that I get is an angled cut, presumably from deflection.  I set blades to the depth to center, never more, for each and every parting job.  I'd love to get a square cut out of a squarely positioned tool.  Any other improvements would be welcome.



Yes they perform better, especially on a mini lathe. Well worth the effort to modify it.

Roy


----------



## mikey (Mar 20, 2019)

pontiac428 said:


> Question for those of you who have modified your cutoff tool holders for P-type blades:  Do they perform better after the modification?



You're basically asking if a P-type blade that is able to sit vertically and rigidly in a tool holder will work better and the answer is yes. There are two ways to get the blade vertical - shim it so the wider cutting edge clears the wall of the holder or cut a slot to do the same thing. I've done both and both ways work but shimming is a lot faster and easier and works just as well. Find some shim material that is even in thickness and stick enough of it behind the body of the blade to allow the top edge of the blade to clear, then tighten the blade down.


----------

