Parting off using quick change tool posts

[steran50]

HI ALL:),
Guys I have Question. The other Day I Parted OFF on My Lathe for the first time. I have a Hafco AL-960B fitted with a Aloris 222 BXA Quick Change Toolpost. The Parting Off Tool Holder for the QCTP has 250-207 Stamped on it. The Tool Holder takes 11/16" in Height Part Off Blades. The Material that I Parted Off was 3/4" (19mm) 1045, the Material Parted Off with No problems at all.

When I was setting the Centre Height for the Part Off Tool Blade. I found that I could not have much Blade sticking out with out having to drop the Tool Holder right to the Bottom of the Toolpost. I didn't have to drop the Tool Holder to the bottom to do the Job at the time. What I realised though is if I want to Part off something say 50 or 65mm in Diameter. I won't be able to, because to have the Part Off Blade sticking out far enough will put it above Centre Height. Has anyone come across this Problem yet?.

[Jekyll and Hyde]

HI ALL:),
Guys I have Question. The other Day I Parted OFF on My Lathe for the first time. I have a Hafco AL-960B fitted with a Aloris 222 BXA Quick Change Toolpost. The Parting Off Tool Holder for the QCTP has 250-207 Stamped on it. The Tool Holder takes 11/16" in Height Part Off Blades. The Material that I Parted Off was 3/4" (19mm) 1045, the Material Parted Off with No problems at all.

When I was setting the Centre Height for the Part Off Tool Blade. I found that I could not have much Blade sticking out with out having to drop the Tool Holder right to the Bottom of the Toolpost. I didn't have to drop the Tool Holder to the bottom to do the Job at the time. What I realised though is if I want to Part off something say 50 or 65mm in Diameter. I won't be able to, because to have the Part Off Blade sticking out far enough will put it above Centre Height. Has anyone come across this Problem yet?.

I have the same numbered tool holder on an AL-335, and have had set it to part off 60mm dia without running out of height adjustment. Then proceeded to have an almighty crash (following on from a smaller one).

The blade is not well secured in my holder, in that as you do up the clamp it cocks the blade on an angle (top out towards spindle), and it requires a lot of force to lock the clamp up tight enough to keep the blade from sliding back in the holder. Not to mention the blade has quite a lot of flex at that extension. I don't think I'll be using mine again for that depth of parting. Works well up to about 1/2 inch depth, beyond that I'm a bit iffy.

Besides, my piece of HSS is a bit bent in the middle now, and I'm yet to replace it... IF I do, I will be grinding it down a bit behind the cutting edge to provide some clearance to the sides of the cut, as I'm pretty sure the cause of the big crash was the blade picking up on the side. Along with that, I will look at improving the hold of the clamp.

Am also considering a good quality (Kennametal/Sandvik etc) carbide insert based tool as an alternative. Fortunately parting off is not something I'm needing to do often, so I have plenty of time to think about it and research it.

Of course, others here have probably been using the same holder for big diameter parting for years without issue, and I'm just an idiot who's done something wrong :- And your holder may not be a H&F version as I suspect mine is, or may be from a better batch, or... etc, etc.

[Bryan]

Stewart, in the thread where you were deciding which toolpost to buy, DaveJ said this:
From memory of my old Hercus I think you would be better off with the AXA size. The tool height is what really matters, if you follow the Aloris links at the top of the page it shows dimensions for it. The BXA might only let you run small tools because of being to high.

Dave

Looks like he might have been right. Don't mean to be a smart-alec, I've just been reading up on toolposts recently, and that stuck in my mind. Probably because I'm trying to decide on the right size to get as well. The thread is here: Quick Change Toolpost Which Is Better (http://www.woodworkforums.com/f65/quick-change-toolpost-better-123112/)

[steran50]

HI:),
Jekyll and Hyde: Do You think that it was the Blade not being well secured that caused the Crash ?. I Bought My Quick Change Toolpost, Extra Holders and Part Off Blades from Shars in the USA. I have had No problems with any of the Holders. My Part Off Tool Holder is good, there is No Cocking of the Blade and the Clamping action seems fine. Maybe the Blade You are using is to thin ?. I Bought varying thickness of Blades, the one I was using is 5/32" (3.97mm) thick. Also the Blade I was using has a 'U' shaped Groove all the way along its Top.
I have been thinking of getting some 5/8" Blades or Grinding the Base of some of the Blades to get the Centre Height down. After the latter I would either make a New Clamping Block or put something inbetween the Clamping Block and the Blade. I will put some 60mm in the Lathe tommorow and see happens with the Height. As You've said that got the Centre Height okay and there is only 2.5mm difference in the Centre Height between the AL-960B and the AL-335.

Bryan: No,You're not being a Smart Alec. It could be right when it comes down to the Part Off Holder. I don't have any Problems with any of My other Lathe Tool Holders. I use 16mm Turning Tool Holders all the Time. I Machined about 3mm off the Top of a Set of HSS Drop Point Tool Holders https://www.machineryhouse.com.au/Products?stockCode=L075R so as I could use HSS on My Lathe with the QCTP. Boring is not a problem either, I have used a 3/4" Boring Bar (would love to have 1" one) with no problems with height.

[Jekyll and Hyde]

Stewart, in the thread where you were deciding which toolpost to buy, DaveJ said this:

Looks like he might have been right. Don't mean to be a smart-alec, I've just been reading up on toolposts recently, and that stuck in my mind. Probably because I'm trying to decide on the right size to get as well. The thread is here: Quick Change Toolpost Which Is Better (http://www.woodworkforums.com/f65/quick-change-toolpost-better-123112/)

Bryan, I believe that was in response to the post below by Kwijibo. The AL960 has a 12 inch swing, same as my AL335, and as I mentioned earlier, I can get that same parting tool holder low enough to do 60mm diameter. I also run a few 16mm tools on my AL335, which is as big as the holders take (without modification).

You have made me think of something though, I wonder how Stewart has mounted his toolpost to his lathe? The base of my toolpost sits directly on top of the compound slide. Perhaps the top of the AL960 compound is closer to centre height than an AL335?

Also, just had a look out of idle curiousity, the AXA version of that tool holder takes the same size HSS as the BXA version, so it can't really go any lower anyway, since the HSS is already very close to the bottom of the holder....
For reference, heres a link to the BXA type holder Stewart and I have:
250-207 #7 UNIV. PARTING BLADE HOLDER-PHASE II :: Quick Change Toolholders | Travers Tool (http://www.travers.com/product.asp?RequestData=CA_Search&q=item_id+%2755-400-207%27&catalog=100266)

Cheers, Ben


kwijibo99[/COLOR] (http://www.woodworkforums.com/members/40428-kwijibo99/)]My Hercus 260 has a 10" swing and I'm considering trying one of these types of tool post but as a 10" swing fits into both the AXA and BXA range I was wondering if anyone else had fitted either to a similar sized lathe?
My feeling is that the BXA may be a bit bulky and have too much overhang from the top slide as the current original 4 way tool post is about 2.5" square which is the same as the AXA size?
Any of you blokes got any thoughts on this? All opinions gratefully received.
Cheers,
Greg.

PS: Bryan, not trying to be a smart alec either, just making observations as they come to mind. :2tsup:

[Jekyll and Hyde]

HI:),
Jekyll and Hyde: Do You think that it was the Blade not being well secured that caused the Crash ?. I Bought My Quick Change Toolpost, Extra Holders and Part Off Blades from Shars in the USA. I have had No problems with any of the Holders. My Part Off Tool Holder is good, there is No Cocking of the Blade and the Clamping action seems fine. Maybe the Blade You are using is to thin ?. I Bought varying thickness of Blades, the one I was using is 5/32" (3.97mm) thick. Also the Blade I was using has a 'U' shaped Groove all the way along its Top.
I have been thinking of getting some 5/8" Blades or Grinding the Base of some of the Blades to get the Centre Height down. After the latter I would either make a New Clamping Block or put something inbetween the Clamping Block and the Blade. I will put some 60mm in the Lathe tommorow and see happens with the Height. As You've said that got the Centre Height okay and there is only 2.5mm difference in the Centre Height between the AL-960B and the AL-335.



I typed slow again!

I suspect the blade not being secure contributed, but I'm sure there are many other factors at play here. My parting blade is thinner than yours, at 3mm x 18mm, and is just plain old rectangular hss. That's how it was when I bought the lathe (S/H), and thats how I used it - it was fine up until I wanted to part something big. I suspect the blade needs SOME sort of profiling on it, but I didn't know any better at the time. If my blade had a groove along the top, that may have helped too, as it may have been that a chip got wedged between blade and cut...

Will be interested to see how you go with setting it up for 60mm, as I mused in the post before, I wonder if the top of the compound on an AL960 is higher with respect to the centre height than an AL335?

[steran50]

HI:) Guys,
Well it seems I made a misjudgement in My concern about getting Centre Height. This Morning just to have a look, I put a Piece of 60mm Solid Round in the lathes Chuck. I put the Part Off Tool Holder on with its Blade (5/32" x 11/16" x 5") and had no trouble getting Centre Height to Part the 60mm Off. I did not have the Lathe under Power I only set the Part Off Tool up as a Practical Exercise to see if I could Part off some 60mm Material.
I decided to go further and see what the Maxium Diameter of Material would be that I could Part Off. I discovered with the Part Off Holder bottomed out the absolute Maxium Diameter I could Part off would be about one hundred & forty millimetre (140mm). The Blade was sticking out about 70mm. I don't think I will be worrying about Parting Off 140mm, I think that would be a bit Scary. The biggest Solid Round Bar I have anyway is 115mm, that too would be Scary I think.
In Conclusion after discovering what Size Diameter Matereial I can Part Off, I would have to say that I am Stoked:D with My Aloris 222 BXA Quick Change Toolpost. I don't know how I made such an error about the Centre Height in the first Place, maybe it was too Dark when I was Working.
Thanks Guys:2tsup:.

P.S. I will actually have a go at Parting Off some 60mm and I will let You know how I go.

[rusty steel]

Call me "Chicken" if you like, but if I am parting anything large in dia. with my HSS parting tool,I usually part some of the way and then move the saddle along about half the thickness of the blade and take another cut and continue a little deeper and then repeat the process ,going a little deeper each time.
Russell

[pipeclay]

Do you only make 2 plunges ,reading what you wrote it seems if it was maybe 100mm OD you would go in maybe 10/20mm with a 3mm blade,move 1.5,go in 20/30,move 1.5,go in 30/50 etc,you would end up about 9mm stepped partoff.

Or do you take your saddle back to your original start point and plunge again for X depth,move to your 2nd plunge point and repeat between the 2 until off.

Do you do this to provide clearance for the swarf to get away from the tool.

[rusty steel]

Hello Pipeclay and others,
To be more precise, I mean't to say that I took a cut about 3mm deep and then moved the saddle towards the chuck 2.0mm (my parting blade is 3.2 mm wide) . I then took a cut down to the depth of the first cut plus another 3mm. I then moved the saddle back to the original position and took a cut down to the 6mm depth plus another 3mm. I kept repeating the process,moving the saddle left and right which resulted in a 5mm wide cut. In practice I found that the blade flexed slightly as I went deeper which resulted in a cut which gradually became less than 5mm as I went deeper. This would have given clearance on the side of the blade. I recently used this method to part a piece of 100mm Dia. 4140 without any problems. I had to keep moving the blade further out of the holder as I went deeper of course. (the centre height stayed the same). I need a bandsaw don't I.
Russell