Quick change tool posts

[SimonM]

I’m getting started with my new to me advance 13x40 lathe and It's becoming obvious that I don’t have the patience to live without a quick change tool post.

Bxa vs Cxa
Is it worth buying the bigger Cxa? My lathe came with boxes of new brazed carbide tooling, some of them would fit better in the Cxa or I could just grind them down.

Piston vs wedge type
Piston type are cheaper, is it worth the money?

Thanks,
Simon

 

[PeterT]

This has been discussed a few times here so maybe do a search. The important thing to know is that not all lathes are created equal in terms of distance from spindle center to top of compound. That is the more defining parameter in terms of toolpost selection & can vary between lathes of identical nominal swing.

 

[Tom Kitta]

Generally 13" would be BXA. The swing usually corresponds a bit to the distance from spindle center to top of compound - but it is more correct to check that. 13" swing is in the lower part of BXA range but still well within it so you would have to had an unusual lathe to not fit BXA. CXA is for bigger lathes - you would have to have unusual lathe at 13" to work with CXA & it will be at its lowest end.

Both piston and wedge are good. Wedge is more forgiving of Chinese larger tool holders on US made tool posts.

There are few threads about this very question already.

 

[Dabbler]

I have both piston and wedge type tool posts, in offshore and Aloris variants. My 12" lathe in AXA in piston achieves all the rgidity necessary for parting and form tool operations. BXA piston is also offshore, sourced from Modern tool, and it gives slightly less convincing grab on the holders than I expected - it is 30% larger after all. Of course the Aloris in wedge BXA is a very satisfying solid holder, and If you can afford it, it is solid as a rock.

my conclusion is that you can't cheap out. A cheap wedge won't be any better than a cheap piston. The better offshore brands are way more expensive than the bargain basement versions. A poorly made CXA won't hold tools as well as a well made BXA. I have BXA on my 14" and 15" lathes. I wouldn't even consider a CXA on my 14" lathe, as my compound to centreline distance won't support it. I could go CXA on the 15" but there is no need. the Aloris BXA will hold any tool I want to use.

-- you can hard mill your holders to fit the BXA, but there are also BXA-XL holders for larger tools, here's an example:
https://www.shars.com/turning-and-facing-holder-1-type-201-xl-bxa

I've milled insert holders to fit my AXA and it works just fine.

 

[SimonM]

Finally got a few minutes to go down to the garage and have a look at my current toolpost and will need to mill/grind some of the tooling I have regardless of the toolpost i choose. Thanks for pointing that out @PeterT.

Looks like there is no need for CXA. Due to my budget which has already been blown with the lathe and mill purchase, the choice will be between a quality used or cheaper import.

 

[Tom Kitta]

I have two piston QCTP - the AXA yesterday turned down per side 2mm on 110mm piece at 100 RPM and moderate feed (forgot the #). I doubt that a QCTP will be the issue for lathe unless you pick BXA for some ultra heavy duty 13" lathe that is like 8000 lbs and has short 40" bed mated to at least 10hp motor & run it close to motor stall.

I guess biggest concern with BXA is that it cannot take cheap large tool holders - you either have to get smaller ones or mill a tool holder to the post. Again this is a bit of a point of concern if you have a very heavy duty machine.

 

[PeterT]

Shars has some useful dimensioned drawings corresponding to the toolpost models, A,B,C etc.
https://www.shars.com/products/tool...uick-change-tool-post-set-piston-type-200-bxa

Sometimes the classic 4-slot tool blocks have some interesting dimensions that may or may not be indicative of your setup capability with modern tool posts. I'm not sure if it has to do with the era, maybe 1/2" was the approximate max HSS blank whereas now a 5/8" is considered a common 'small' tool shank for insert carbides. To add confusion, sometimes when you see 5/8 or 0.625 (which is 15.875mm) it can also mean they are trying to North-Americanize the dimension & the slot can accommodate 16mm (metric) tool shanks like example attachment. 16mm = 0.630" ... see what I mean?

My experience has been the toolholder blocks can be milled but its not exactly fun. They can be made from pretty tough stuff & heat treated, but I've also heard of softer variations like Dabbler says. It seems to depend on origin. The offshore grade toolholder shanks themselves can be something like ordinary 4140 steel but they can also vary. I've successfully cut & milled them although not for this purpose. A high quality N-Am shank can be very tough stuff, so even if its free, milling it down isn't worth the headache IMO when you can buy an offshore shank for under $10.

I have a 14x40 lathe & 15-16mm is the biggest tool shank I can run based on the tool holder block. Although I don't do a lot of heavy load carving its rigid enough for my purposes. I tend to favor CCMT & DCMT inserts. Probably if I had to choose one I'd get DCMT. Anyways take your time to consider the variables & pros/cons because it sets up a chain reaction of other tooling. Or ask any questions if this isn't clear.

 

[Dabbler]

They can be made from pretty tough stuff & heat treated, but I've also heard of softer variations like Dabbler says.

@PeterT I didn't say it was easy. I wrecked one carbide end mill completely and dulled another before it was done. This was on an offshore tool. I wouldn't try it on a Kinemetal with a normal carbide end mill Fortunately I now have 'hard-milling' end mills - I try to learn from my mistakes.

-- yes it is possible to mill out the tools to fit. Much cheaper to buy BXA - XL tool holders. I have 5 tools that are 3/4" square. I'll be buying 5 BXA-XL QCTP holders. (I don't have them yet. Priorities.) They are still half the price of cheap CXA tool holders.

A quick consideration @SimonM - I've set up my 4-way to be centred with 3/4 inch tools, and my QCTP holders will also centre them with the 3/4 inch tools. That wy I can use the 4-way WITHOUT SHIMMING TO GET TO CENTRE. So many guys miss the fact that with a few minutes of prep, every tool you slap in the 4-way is perfectly centred without adjustment or shims.

The mistake that YYC made is all too commom with any of the qctp holders and never happens on a 4-way, properly set up - once, not every time you use it.

4 way tool holders are way better than a qctp for 80% of turning. I didn't have a qctp for 36 years, and then I tried it on my 12". It worked okay and I use it about 50% of the time. I only got a BXA piston QCTP on my 14", so I bought a 4-way to retrofit it onto that lathe. For the LeBlond 15", I bought the Aloris as a splurge and an addition to the extremely solid 4-way - there are times the qctp is better as well.

I'm not religious on the matter. I've use Aloris type QCTP, touch briefly on Davidson type, used Multifix type (they're superior to everything until they're not) and 4 ways. I first learned on rocker tool posts. I'll use whatever is on the lathe.

You can use any of these effectively if you make a height standard fitted to your lathe, and do a minimum of prep.

 

[SimonM]

Thanks all for the wisdom.
Looks like I will need to spend some time with the machine and figure out what my actual needs are.

I bought the machine from a fella in his 80s that got it after retiring from his machinist day job and he most likely has hoarding issues. I got several boxes of brazed and some insert carbide tooling with the machine and would hate it to go to waste. They are all new kennametal and sandvik, not junk. That was my reasoning behind getting the biggest toolpost that could fit on the machine.

@Tom Kitta Machine is about 1500lbs and 2hp, looking at the cuts you are taking with the AXA, it seems like it would never be a limiting factor rigidity wise.

@PeterT after looking at the height to center, cost of subsequent tooling and all other factors, I’m starting to think that my original idea might provide no real benefit and cost quite more.

@Dabbler will try those tricks with the 4 way until I figure out exactly what I need. I would like a QCTP mostly for speed, my time is limited with 2 kids under 2 and I’m always on call. Every minute counts!

 

[Billy]

I have two piston QCTP - the AXA yesterday turned down per side 2mm on 110mm piece at 100 RPM and moderate feed (forgot the #). I doubt that a QCTP will be the issue for lathe unless you pick BXA for some ultra heavy duty 13" lathe that is like 8000 lbs and has short 40" bed mated to at least 10hp motor & run it close to motor stall.

I guess biggest concern with BXA is that it cannot take cheap large tool holders - you either have to get smaller ones or mill a tool holder to the post. Again this is a bit of a point of concern if you have a very heavy duty machine.

I have several large size bxa holders I bought them here https://www.ebay.com/itm/283798231031

 

[Dabbler]

Just as an addendum to my post #8 above, The QCTP I was referring to was not "Davidson" but "Dixon" I made that mistake for several years, but I hope that is behind me.

I bought a 100mm Dixon tool post for my big lathe. I find that even the genuine Aloris is not as rigid as I'd like for parting off and form tools. Yes I could use my 4-way, but I wanted to try the Dixon. It is similar in size to an Aloris CXA bit I think it weighs more.

I'm non-parochial about the different types of tool posts. One day I'll make a rocker type for my big lathe if I can find appropriate sized Armstrong holders for it. Each one has its plusses and minuses. I really don't mind switching tool posts as required.

@SimonM the 4-way can be just as fast or faster than an Aloris QCTP if all you need is 4 tools and they are set up correctly. Just a thought...

 

[Former Member]

One my first lathe I made a 4 way tool post and you are going to find that after a while you tend to use only 2 or 3 positions on the post and if you are using carbide insert after you figured out center changing is even easier, center tends to remain the same holder insert holder to holder in a set so changing becomes a no brainer.

I now use quick change holders and yes they allow changes quick, on a select few a 4 position holder is way quicker with the right setup. They only draw back is cost, every tool gets a holder. So you convenience is of set by the number of $ you have or are willing to part with.

 

[ducdon]

My Modern Tool 14X40 came with a BXA so that's what I use. I do have some additional holders that fit up to 1 inch tooling, a 1 inch boring bar. I never seem to have enough holders so I'm making a batch with openings for different size tooling. They are cold rolled steel no hardening of any kind. I don't do a great deal of heavy turning so I assume they will work just fine.

 

[trevj]

I made a clone(ish) of the Tripan 111 tool post for my Myford lathe. Started with a couple 111 tool holders, figured out the magic of the 60 degree angle, and ran with it.

I made foot long sections of blank, dovetailed tool holders for same. Once you have a decent dovetail, you are pretty much able to make about anything you want! I used 12L14! They are working very well!

I recall reading an article on shop made tool holders, and the guy emphasized one particular point. That was, that the hardened and ground tool holders, were that way, to withstand the handling by the lowest form of trained monkey that might use them (not his exact words), so if you wanted to use brass, it would work just fine, as long as you treated it with a modicum of respect!

 

[trevj]

Oh, now that's just funny!

I just sent 140mower a PM, and up pops his response to my last post! Hilarious!

Same home town!

 

[Chipper5783]

As per comments above, the 4 way tool post is a very good arrangement for holding lathe tools and is not uncommon in commercial shops. That is what I used for over 30 years. I have gone to a CXA Phase II (15” swing lathe) and I have about 15 assorted tool holders - it is nice to have lots of mounted tools. The CXA is good, but it is not as solid as the turret (changing back is a pain as the compound slide has to come apart to change the center post).

I suggest you just go with the existing turret - there will be plenty else to spend money on.

 

[140mower]

Oh, now that's just funny!

I just sent 140mower a PM, and up pops his response to my last post! Hilarious!

Same home town!

If we can get one more person from town to join I think we would have the highest percentage per capita on the forum. Might be there now.....

 

[ducdon]

I made a clone(ish) of the Tripan 111 tool post for my Myford lathe. Started with a couple 111 tool holders, figured out the magic of the 60 degree angle, and ran with it.

I made foot long sections of blank, dovetailed tool holders for same. Once you have a decent dovetail, you are pretty much able to make about anything you want! I used 12L14! They are working very well!

I recall reading an article on shop made tool holders, and the guy emphasized one particular point. That was, that the hardened and ground tool holders, were that way, to withstand the handling by the lowest form of trained monkey that might use them (not his exact words), so if you wanted to use brass, it would work just fine, as long as you treated it with a modicum of respect!

The part about getting the dovetail right is absolutely true. I made the dovetail cutter with just one cutting insert. Cutting them took more than a little while. The difference between a tight and a loose fit isn't very much.

 

[trevj]

If we can get one more person from town to join I think we would have the highest percentage per capita on the forum. Might be there now.....

I'll talk to Mick, about that, next time I see him!

Sorta reminds me of the guy that chucked two dozen or so iPhones in to his kiddies wagon, and parked them along a normally busy thoroughfare. Apple decided that so many of their phones were not moving in one spot, that it must mean a traffic jam, and routed all the traffic hells and away from where it usually ran!

Just another way to manipulate the statistics, eh?

As a side note. Statistics are a lot like Bikinis! What they reveal may be fascinating, but what they conceal, could well be critical!

 

[trevj]

The part about getting the dovetail right is absolutely true. I made the dovetail cutter with just one cutting insert. Cutting them took more than a little while. The difference between a tight and a loose fit isn't very much.

Yeah. I never found it a problem to hit a dovetail dimension once I had worked out the Trig around it. A couple ground pins and a internal Mic, and you can play the spring pass games to get exactly on size!

The 60 degree angle of the Tripan tool post allows you to put both a turning and facing tool that does not touch, other than where it cuts, as well as a boring tool, that acts the same.
I made a BUNCH of tool holder stock out of hex 12L14 that was big enough to account for that angle.

As a silly side note, me, and the guy who was working on the mill beside me, on a Military Machining course, made a pair of plates with a rotary dovetail, essentially a quarter of a circle, I made the male dovetail, he made the female. This was on 4 x 4 inch plates, on a rotary table, on a manual mill.

At the start, we made the 4x4 plates, then drilled and reamed a 1/2 inch hole at dead center of the plate. Then we made our respective halves of the dovetail. When we pulled them off the table and fitted them together, they worked very well. When we were able to press a dowel pin through the half inch hole in the middle, while the two pieces were assembled, even the Instructor was impressed!