Ross- Rumor has it you possess a Deckel buttress thread carbide insert...if guilty

[Milacron]

as charged, where did you get it and what make of holder does it fit ? (for external threads in this case, but would be cool if the same insert fit a boring bar as well....talking the usual S20 x 2 Deckel drawbar here)

 

[AlfaGTA]

Guilty as charged, but i am not positive they cut to the Deckel form.....
Someone posted on this board a drawing of a real Deckel collet to include the true shape of the thread...Searched but i couldn't find the info today
If its the same as the current standard then it should be 45-3*
The US standard is 45-7*
I have compared as best i can to a collet and they look pretty close....
For draw bar i think they would be OK....

Inserts are made by :
"Tool-Flo" And the numbers are: FLTB-2RA AT3 and FLTB-2RB 3AT
They are made to cut with the thrust face to the right or to the left depending on which way you are running the part, you have to change the insert.

The Outside holder is also Tool-Flo and part FLSR-122B that is a 3/4" square stick holder...Right hand.

These inserts will also work on the proper boring holder......Sandvik bars :SI-CTLHOR-05102 L6M will work but requires re-profiling the top clamp to hold the insert properly.....


Have had these for some time and i tried to look up the numbers, but drew a blank....
Cheers Ross

 

[ballen]

I know that this thread is a couple of years old, but I wanted to add a bit to the information here.

The Tool-Flo inserts that Ross identifies are for an American Standard Buttress thread which is 7 degrees on the pressure flank and 45 degrees on the clearance flank. The buttress thread used in Deckel S20x2 drawbars and collets, as well as the buttress thread used in Schaublin W20 and W25 collets, is 5 degrees on the pressure flank and 45 degrees on the clearance flank. In practice, these are close enough that it should not matter. If you are compulsive about such things, angle the toolholder 2 degrees so that the pressure flank (which is the one that matters the most) is at the correct angle and the clearance flank is "off" by 2 degrees.

 

[bsg]

I know that this thread is a couple of years old, but I wanted to add a bit to the information here.

The Tool-Flo inserts that Ross identifies are for an American Standard Buttress thread which is 7 degrees on the pressure flank and 45 degrees on the clearance flank. The buttress thread used in Deckel S20x2 drawbars and collets, as well as the buttress thread used in Schaublin W20 and W25 collets, is 5 degrees on the pressure flank and 45 degrees on the clearance flank. In practice, these are close enough that it should not matter. If you are compulsive about such things, angle the toolholder 2 degrees so that the pressure flank (which is the one that matters the most) is at the correct angle and the clearance flank is "off" by 2 degrees.

Or you could split the difference, and have both sides off one degree?

 

[rklopp]

Or do it right, and grind the appropriate tool. That's how I cut W20 buttress threads on arbors for my old Aciera F2, which I since sold.

 

[Peter from Holland]

I must have a boring bar somewhere with brazed carbide that was cut the right shape with a wire edm
You could sharpen it from the top I believe
Never used it

Peter

 

[AlfaGTA]

Or do it right, and grind the appropriate tool. That's how I cut W20 buttress threads on arbors for my old Aciera F2, which I since sold.

Verified on a calibrated optical compartor of course....

Cheers Ross

 

[rklopp]

Verified on a calibrated optical compartor of course....

Cheers Ross

I’m hosed in that regard in my garage shop. I did the best I could with the angular settings of a Glendo tool grinder.


Sent from my iPhone using Tapatalk

 

[AlfaGTA]

And how did you set the tool to the work?
My point is that grinding a tool is fine, but i am pretty sure your tool was not exactly at the specified angles...and likely not set
perfect to the part axis....

In reality the buttress thread employed by Deckel and Maho among others is stupid overkill.....Not that much force on the draw bar ...
Other makers have used 60* unified or metric threads on their draw bars for eons...with no real short fall as far as i can see.....
So making a tool or drawbar that misses the exact angles by a degree or so IMO is no big deal....Its not like this is a jack screw lifting a locomotive.


At least by using an insert tool you can set the holder square to the work fairly easily and be pretty sure the angles will be orientated correctly.
Cheers Ross

 

[rklopp]

I get the tool-to-work angle set by first grinding the cutting edge angles relative to the straight shank of the tool, which is the way most folks would do it, I think. Then, if I square up the shank to the work, I should be theoretically correct. Of course it's not perfect, but should be close. I square up the shank to the work using a square, the faced stock, the face of the chuck, the end of the tailstock ram, or whatever else is handy and pointing in the right direction. I suppose I could get fancy and set the cutting edge angles with a sine bar and indicate the side of the tool shank in the lathe, but that's not necessary for any screw threads I have ever cut.