Parting Trick

[jschmidling]

Will be interesting to see how the 1/16" blade works.

Actually, it doesn't work.

First of all, I didn't read the description through and missed the fact that it is a "T" profile and I see no way this could be mounted in my rear mounted holder or in the QCTP. It can't stand vertical just by tightening the hold down screws and it squeels like a Banshee in use.

Secondly, it is bowed and there is no way to square it with the part.

Third, it is not really a T. It is quite lopsided. Almost no relief on one side and all the rest on the other. It works a little better on the low relief side but still can not be square without shimming or some other bandaid.

In the information it states that P type implies or defines a T profile.

My P2 blade is perfectly flat and parallel and sits square in the holder when the screws are tightened.

What am I missing here?

Jack

 

[ddickey]

Pics or a link?

 

[mikey]

What am I missing here?

What you're missing is that it sounds like you did not buy a P-type blade. Instead, you bought a "beveled-type" blade; a common source for these is China. Note that the side of the tool are simply beveled from top to bottom; there is no wider cutting edge



A P-type tool has a distinct top profile. It originally had a flat top but many also have a concave scoop on top nowadays. Patented by Luers, the P-type design had a 5 degree side bevel ground into the cutting insert material.



The T-type blades are very similar to the P-type; I am not clear on their side bevel angle. You can essentially consider the P- and T-type blades functionally the same.

 

[NortonDommi]

Yep, bevelled blade and they only go one way in the holder and that is with the flat square to the top side against the holder, thick bit,top, at the top.

 

[ddickey]

These are T types.

T-Type Cut-Off Blades H.S.S. | Somma Tool Company

View our line of T-Type Cut-Off Blades H.S.S.

www.sommatool.com

 

[jschmidling]

What you're missing is that it sounds like you did not buy a P-type blade. Instead, you bought a "beveled-type" blade; a common source for these is

It's not beveled. The thickness of the non-cutting part is constant. Looks like a surface grinder step. Problem is that the step is much deeper on one side than the other. More like an "L" than a "T". If it were flat on one side, it would work if that side is pressed against the holder but there is still a small step there forcing it out of square.

I gave up trying to get a better pic, but you can get the idea from this...






I called LMS and all I could learn was that he would send another one out.

Here is a link to it...

Cut-Off Blade, P1 1929

Cut-Off Tools 1929 This blade is size P1.; High Speed Steel; Width: 1/16", Height: 1/2", Length: 4-1/2"; Our Lathe Cut-Off Blade is made with M2 high ...

littlemachineshop.com

Seems to me that one needs a special holder for a T profile.

Jack

 

[mikey]

Why not buy a decent blade from AR Warner or Somma? A parting blade can last a quarter century or more if cared for - spend the money on a good blade.

 

[jschmidling]

Why not buy a decent blade from AR Warner or Somma? A parting blade can last a quarter century or more if cared for -

Several very good reasons:

1. I will be 105 about that time and I figured that $7 worth is about all I would need.

2. I lost shop, business and 50 years of treasure in a recent fire and replacing everything with the highest quality just is not within my budget.

3. Most of the companies I grew up with and respected no longer exist and the ones that do make everything in China and we have no way of sorting Chinese Junk from quality anymore.

4. I gathered that LMS was highly respected by this group and thought I would get what they advertised.

5. Until someone like you comes along and recommends a quality product, I am just groping in the dark and go for bargains assuming no great loss if junk.

Other than that, thanks for your help.

Jack

 

[mikey]

Jack, I understand being on a budget, which is why buying good stuff matters - buy the right thing once and take care of it and it will outlast you. I have an Eclipse P1-N parting blade that has been in use for nearly 30 years and it is still going strong; it was my first parting blade ever and I still reach for it whenever I part on my Sherline lathe. If you cannot afford a decent blade, PM me your personal address and I'll send you a good one.

 

[royesses]

It's not beveled. The thickness of the non-cutting part is constant. Looks like a surface grinder step. Problem is that the step is much deeper on one side than the other. More like an "L" than a "T". If it were flat on one side, it would work if that side is pressed against the holder but there is still a small step there forcing it out of square.

I gave up trying to get a better pic, but you can get the idea from this...


View attachment 299771



I called LMS and all I could learn was that he would send another one out.

Here is a link to it...

Cut-Off Blade, P1 1929

Cut-Off Tools 1929 This blade is size P1.; High Speed Steel; Width: 1/16", Height: 1/2", Length: 4-1/2"; Our Lathe Cut-Off Blade is made with M2 high ...

littlemachineshop.com

Seems to me that one needs a special holder for a T profile.

Jack

I have 2 P1 blades from LMS and they are symmetrical, unlike yours. Looks like you got a factory defect.
My holder for my 0XA QCTP is this:


Roy