Blade for QCTP cutting tool

[hacklordsniper]

With my new lathe i recieved a QCTP and also a tool holder for cutout blade. I was also delivered 10 PCS rectangular blades, but they simply cannot be held in there since holder pushes the blade out sideways when tightening it. I have found info i need a trapezoidal blade, so i ordered it. Now i found out that this blade is also pushed outside when tightening, can someone help me and tell me what kind of blade i need?

 

[canadianhorsepower]

to what I can see yourblack block is upside down the recess should be inside top
and of course the wider part on top
good luck
This is only a guess cause I don't have that same set up

 

[MCRIPPPer]

maybe you need to machine the clamping faces square. if its a cheapychina one it might need some TLC to get it to work right. looks like it is assembled correctly to me.

 

[hacklordsniper]

looking at the manufacturers pictures, im sure it is assembled right. Im not sure there should be any machining done on it, this are usually verry good quality tool holders

 

[canadianhorsepower]

looking at the manufacturers pictures, im sure it is assembled right. Im not sure there should be any machining done on it, this are usually verry good quality tool holders

What brand and part number is it

 

[gus]

Bought the HSS Parting Blade from LMS and it cut/part well but ample Tapmatic Fluid required.
DIY QC Tool Post and tool holders. Been using this parting tool for the last five years.

 

[tornitore45]

All my parting difficulties went away when I followed somebody advise to grind a small hollow on top of the tool. A V shape or a an arc work fine. It is difficult to grind free hand, unless I am in a hurry I use a 3/16" mounted stone on the mill and do 1/2" which will last many a sharpening.

 

[goldstar31]

All my parting difficulties went away when I followed somebody advise to grind a small hollow on top of the tool. A V shape or a an arc work fine. It is difficult to grind free hand, unless I am in a hurry I use a 3/16" mounted stone on the mill and do 1/2" which will last many a sharpening.

Agreed. I went further and followed George Thomas's inverted rear tool post which has the 140 degree Vee( as Tourniture hints) but is inclined at a I think 140 degrees( It's so long since).

It is so long since I made the thing that I have really forgotten. What happens- and I hope T agrees, the ribbon of swarf is narrowed to avoid nipping or seizing. Being upside down, my little curls( oooh) fall out of the cut.

After all, if you want to part off 2" round on a model makers lathe, one only needs to grind a 1" vee.

All in Model Engineers Workshop Manual or Volume 142 in Model Engineer.

 

[tornitore45]

Actually the V groove does not need to be as long as the radius of the stock.
The V grove action is only needed for a few mm.

The rear post not only let the chip fall out, but the cutting stress "pivot" the post to reduce the DOC under load resulting in an equilibrium of stress vs. DOC.

When parting with the tool in the compound the situation is reversed, as the tool is flexed down, it tends to advance into a deeper cut resulting in a grater down force producing an ever deeper cut until it snaps back, the cycle repeat and is called chatter.

I did build a rear tool post, but since I learned about the V groove I rarely part with the rear post since it requires winding the cross slide a lot.

 

[goldstar31]

Agreed but I don't have( or more correctly don't use) one of these damned so called Quick Change affairs.

It is cheaper, easier and more rigid to have a collection of four tool turrets made from all of 3 bits of flat metal and held down with 4 socket bolts.

Actually I have a the Thomas but the fabricated rear one which Martin Cleeve made. If you have Model Engineer, Cleeve wrote 'Turrets without Milling'

You see, I'm a millionaire and that's how I became one----------------------dead mean! I gave my wallet spanner away to charity:hDe:

Happy Christmas

 

[Chiptosser]

Hacklordsniper,

Check to make sure that the angles cut in the toolholder, matches the angles cut on the blade.
This is what holds the tool into the holder.
As mentioned earlier, the top of the blade is wider than the bottom, for clearance while cutting.
The angles help pull the tool into towards the holder , to center the clearance on both sides of the tool.

 

[hacklordsniper]

A friendly machinist explained me what is the problem. This toolpost can use only blade it is designed for (blade height). Anything larger will push the blade out as the block that pushes blade has a certain elevated back that contacts the tool holder when blade is proper height. However it can be easily solved by inserting a piece of HSS below the clamping block (easily calculated, HSS piece= current blade in mm - required blade in mm).

But unfortunately i cannot use this toolpost in my lathe, it is missing height. Not sure but it seems i have little bit too small QCTP and with all adjustment used my tools are below center.

 

[DJP]

I have a very simple holder with four cutters held in by Allen screws. Each tool can be adjusted in height using shims but if the entire tool holder is too low consider adding shim plates to raise it up. This will raise all tool positions in my case. A longer retaining bolt may be required.

I wouldn't give up on your new tool holder so quickly.

 

[hacklordsniper]

Well actually i allready gave up, it seems the manufacturer made a mistake and mounted wrong QCTP to my machine, it is to small for swing of my lathe. So im packing the toolpost and 14 tool holders and sending them back to China, and they will send me a new larger QCTP.