Trouble with parting off

[george wilson]

The cutoff tool also needs to be perfectly VERTICAL. Those old,tapered cutoff tools are often not quite vertical in the tool holder. I always had to shim mine to get them perfectly vertical. If you don't do this, thin pieces you are cutting off can come out cupped from pressure the cutoff tool exerted while rubbing. A person on another forum had this problem,and was hammering his cut off parts flat,which isn't good practice. He got rid of the problem when I suggested his tool wasn't vertical.

And,it is a real pain to use the old fashioned cutoff tool holders in the old lantern tool posts. If you don't have an Aloris TYPE tool holder,save up and get at the least an Asian one. The best type is the wedge type,NOT the piston types,which are cheaper. Wedge type sucks the tool holder up against the tool block. Piston pushes it away,and jams it on the dovetail. That type isn't as rigid. Either type beats the lantern type,though.

 

[Zigeuner]

David said:
With brass, 360 in particular, I tend to go for much higher speeds. If the geometry is right there is no problem. If the geometry is wrong no amount of slowing down or 'feeling' will make it cut better.

You have managed to sneak in two "ifs" into the above otherwise positive statement.

I presume, then, that you set the machine on automatic feed, start parting off and then leave for a cup of coffee....since you have the correct geometry, no "feel" is necessary.

The problem with many of these responses is/are the "ifs" and the "hard and fast" (pun intended) rules that posters like to establish. Since this is still the hobby machinist site. Thus, I don't see the benefit of doing anything fast.

I remain inconvinced that I shouldn't go slow and "feel" all of my work, since I'm not doing it for a living. But I mean that in a nice way....you feel me?

 

[AlanP]

Well I didn't expect my simple question to go to three pages, but I have read all the advice several times. This afternoon, armed with all the good advice I had another go at parting off. 8mm mild steel bar parted off twice, magic, over the moon so I thought I would quite while I was ahead

Thanks to you all

Alan

 

[jgedde]

Glad to hear you were successful! This forum is hand-down the friendliest out there. Folks here want to help and actually do whilst never forgetting that they were a learner once themselves (although some may not be able to remember back that far! ). You ask a good question here and you get good answers without being put down as if you're asking for The Secrets of the Ancients.

John

 

[FarFar]

I am new here and do not fear parting off.
I have done at least 10 cuts of 100 mm mild steel of unknown parentage and a single 125 mm seawater resistant aluminium all without cutting fluids as I do not like the mess and smell.
My lathe is a rock steady Boxford and there is a picture of it in the wellcome section(Help needed with linking please)
The tools used are not cheap but are still alive and well and are not difficult to regrind ( I hope)
If You go to the HMSE site and seek Carbide partoff Tooling started by an expert Quinette.
It has some pictures of my tooling system .(More linking help please?)
To get started You need two insert carrying blades from ISCAR type TGFH either 26-4 or 32-4 and a skilled wire sparker or grinder .I have some surplus TAG 2J and TAG 4 J to sell and with two of each You have for rest of Your remaining machining.
Rigidity is the key.

Kind regards

Niels Abildgaard
[attachimg=1]

 

[FarFar]

Sorry

Made a typing error

The pictures of my parting of system is on Home Model Engine Machinist in the Specialist section

http://www.homemodelenginemachinist.com/index.php?topic=10922.0

I have somehow lost the pictures on my computer

Regards

Niels

 

[Mueller]

Only have enough blade sticking out of the holder to get the job done. More is to invite trouble.