# What's the Differance? Tool Post Styles, Piston or Wedge



## Rd2nowr

Ok, so what's the difference between a piston QCTP and the wedge type? Pro's and cons of both? Shar's has the AXA piston type in a set for $114. and the wedge type for $183.
Thanks, Tim


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## Joe P.

It's the way the tool post locks the tool holder in place. Correct me if I am wrong but I believe the wedge type holds the tool holder not only tighter but more accurately as well. 


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## Charles Spencer

I have both types.

The piston type pushes the tool holder out from the tool post to force it against the dovetail.  The wedge type drives down a wedge for the same purpose.

I have them on two SB 9s.  I haven't had any trouble with either one.


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## Dave Paine

I have the wedge type on a lathe I purchased from a friend.  No issues with my toolholder.   The friend got a new lathe and a piston type.  He has commented he prefers the wedge type.  I did not try to get details on the difference.


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## Bill Gruby

The difference has been stated above but I will add that the piston type pushes the holder away from the base while the wedge type brings the holder closer to the base. So my take is that the wedge type is the better holder. I have used both.

 "Billy G"


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## Rd2nowr

Charles Spencer said:


> I have both types.
> 
> The piston type pushes the tool holder out from the tool post to force it against the dovetail.  The wedge type drives down a wedge for the same purpose.
> 
> I have them on two SB 9s.  I haven't had any trouble with either one.


So the AXA is the correct size?


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## DHarris

Size of the tool post depends on the size of your lathe. What lathe do you have?


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## Bob Korves

Both tool post types work just fine.  Get the wedge type if it is about the same price.  It if is a lot more expensive, then go with the piston type.  The only thing that is really at issue here is repeatability, that is taking off the tool holder and then putting it back on again, and expecting the tool to be in the same place again, exactly.  How often is that really an issue with a lathe, and if  it was .001" vs. .0005", would that cause huge problems?


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## T Bredehoft

I've used both, have no preference from experience.  Having said that, I note from the descriptions above, that while the piston type pushes the tool away from the post, putting pressure on the dovetails, the wedge type pulls the tool toward the tool post putting pressure on one of the dovetails (the wedge is not rigid, usually formed sheet metal) and the flat surfaces of the tool post, being somewhat more secure. This is from logic, I'd want to study both with indicators before making a positive judgement. In other words, which cutting tool would wobble more when clamped.


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## Charles Spencer

Rd2nowr said:


> So the AXA is the correct size?



For my lathes it is.  I understand that AXA is good to about 12".


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## Bill Gruby

Yes an AXA will fit a lathe 6 to 12 inches


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## Bob Korves

T Bredehoft said:


> I've used both, have no preference from experience.  Having said that, I note from the descriptions above, that while the piston type pushes the tool away from the post, putting pressure on the dovetails, the wedge type pulls the tool toward the tool post putting pressure on one of the dovetails (the wedge is not rigid, usually formed sheet metal) and the flat surfaces of the tool post, being somewhat more secure. This is from logic, I'd want to study both with indicators before making a positive judgement. In other words, which cutting tool would wobble more when clamped.


Neither should wobble at all when clamped...  It is about repeatability.  The piston pushes the tool holder, and the two dovetails hold the toolholder in place.  If you do it twice, the tool holder might be twisted very slightly up on one dovetail and down on the other dovetail, compared to the previous mounting.  The wedge style tries to minimize that by only moving on one side, while the other side settles better into the opposite dovetail.  We are talking about a tiny amount of possible difference in repeatability.  Once they are clamped down, both styles are solidly rigid to all but major crashes.


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## dlane

Wedge, pressure on 2 Ddovetails, better than one


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## Rick Berk

Without question I would spend the extra for a wedge, I have a Dorian AXA on my 13X40 and rate it a 10 for size and performance.


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## 12bolts

Piston style still locates against 2 dovetails..........

Cheers Phil


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## wawoodman

The prevailing wisdom is that wedge is better, and when there was a substantial price difference, many of us went for the piston. However, that difference seems to be eroding, so, now, I would go for the wedge.


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## BGHansen

Contact surface when the tool holder is locked in place on a wedge style is greater than a piston style so theoretically it'd hold better.  Piston style makes contact on the dovetails and the piston itself.  The wedge style makes contact on the dovetails and the surface of the tool holder/post.

That being said, as Bob mentioned above, you'd be fine with a piston style if it's that much cheaper.  I have a Grizzly G0709 lathe which came with a piston style holder.  Have a wedge style on my Clausing 12" and my Rockwell 10".  I've added a taper attachment, 5-C lever style collet closer and DRO to the Grizzly (plus around 35 tool holders), never felt the need to replace the stock piston-style tool holder with a wedge style on that lathe.

Bruce


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## jbolt

I have done testing on both types (BXA size), using various brands of holders, using a TDI and actual cutting. 

The piston type is more prone to repeatability errors depending on the fit of the holder to the tool post. A loose fitting holder can be locked up slightly tilted fore or aft several thousands of an inch where a tighter fitting holder is more likely to true up when tightened. This can be dealt with by applying pressure to the front or back of the tool holder when locking to fully seat the dovetail.

Some holders from other manufactures may not fit the piston type holders due to that large variation in dovetail dimensions between manufacturers. I have not run across this problem with the wedge type. 

As stated above the contact area between the holder and tool post is greater with the wedge type but in the testing I have done, taking maximum turning and parting cuts, the real world performance was negligible between the two.

That being said my personal preference is the wedge type because any brand of holder will fit and there is less chance for repeatability errors.


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## JR49

Rd2nowr said:


> Ok, so what's the difference between a piston QCTP and the wedge type? Pro's and cons of both? Shar's has the AXA piston type in a set for $114. and the wedge type for $183.
> Thanks, Tim



Tim, first thing, my vote goes to the wedge type.  But my reason for replying is that I think you should shop around a little more.  The price difference you quoted seems way too wide.  When I bought my Phase II wedge toolpost set I'm pretty sure the difference was only about 25 bucks, off coarse that was from the now (sadly) gone Enco. Hope this helps,  JR49

EDIT: 

https://www.amazon.com/dp/B01GVWBBA8?m=A3H367CBPE368U&ref_=v_sp_detail_page


https://www.amazon.com/dp/B002YPDQ4G?m=A3H367CBPE368U&ref_=v_sp_detail_page


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## coherent

I bought the Shars AXA wedge type kit and and happy with it. Solid and well made in my opinion especially for the hobbyist.
You can save a bit on the Shars AXA kit on Amazon or even more on Ebay. I just looked and it's $120 plus shipping, or you can get the toolpost only for about $67 and add a just one or two holders, but the kit is a pretty good deal and the mix of holders and the knurling tool (works fine for aluminum and mild steel) is nice to have. There are other import brands but I haven't personally seen or tried other than the Shars so like anything I'm sure quality varies.


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## Rd2nowr

JR49 said:


> Tim, first thing, my vote goes to the wedge type.  But my reason for replying is that I think you should shop around a little more.  The price difference you quoted seems way too wide.  When I bought my Phase II wedge toolpost set I'm pretty sure the difference was only about 25 bucks, off coarse that was from the now (sadly) gone Enco. Hope this helps,  JR49
> 
> EDIT:
> 
> https://www.amazon.com/dp/B01GVWBBA8?m=A3H367CBPE368U&ref_=v_sp_detail_page
> 
> 
> https://www.amazon.com/dp/B002YPDQ4G?m=A3H367CBPE368U&ref_=v_sp_detail_page


I appreciate all of the replies to this simple question. I looked at Shar's and the prices are the on-line price. I will shop around more. I have the lantern post with all the different holders, but when I try to set the post, it seems its way to high with the angle of the holder. I move the wedge but it seems to not have enough over the compound.


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## Charles Spencer

Shars sells on ebay as discount_machine.  They have the wedge post AXA set for $120 plus $15 shipping:

http://www.ebay.com/itm/Shars-6-12-...914635?hash=item45f3603f8b:g:GBsAAOSwu4BVtmTg


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## Cadillac STS

This topic shows up once in a while with very similar responses.

Is it too off topic to throw in here whether it is better to spend more for a Phase II, Dorian or genuine-authentic Aloris brand QCTP?  Or it the lowest price model just as good?


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## willthedancer

Wedge type. 4 points of full dovetail contact.

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## intjonmiller

I recall seeing literature from Dorian or Aloris that confirmed that the wedge type is more accurate and repeatable, and I am at least 95% sure they also said it's more rigid. 

I actually just ordered the Shars AXA from the eBay store for myself. The eBay store is almost always cheaper than their own site. Note that if you are ordering multiple items from them they will combine shipping. My combined order was $12 cheaper to ship than the sum of the listed shipping prices of all items. Be warned, though, that apparently the policy has changed since I last did it so you can no longer add items to your cart and request a combined total from the seller and then decide if you want to purchase based on the final total. Now by requesting the total you are committing to the purchase. I don't care for that policy, but Shars always seems to discount it appreciably.


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## tweinke

Could the repeatability of the wedge type be better because the wedge moves downward when tightening the tool holder thus helping the holder stay down? I bought a Bostar AXA wedge tool post and holders from CDCO on Ebay and have been happy with it.


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## mikey

Cadillac STS said:


> This topic shows up once in a while with very similar responses.
> 
> Is it too off topic to throw in here whether it is better to spend more for a Phase II, Dorian or genuine-authentic Aloris brand QCTP?  Or it the lowest price model just as good?



From what I have seen, most of these contraptions work equally well or nearly so. A QCTP is not a really complicated tool so if all the pieces are there then they should work pretty well, I think. I don't own an Asian tool post so you should totally discount what I have to say about them. I do, however, own both an Aloris and a Dorian tool post and I can tell you that the fit and finish of both are better than the Asian examples I have seen with my own eyes. Both are very smooth and work flawlessly. Of the two, the Dorian is more finely machined and finished; in fact, its a work of art.

As for repeatability, I don't know that they will repeat any better than an Asian one will. I always check tool height with a tool height gage before using a tool that I just installed and more often than not, even with genuine Aloris tool holders but also with Phase II holders, I need to make an adjustment. If I wipe the underside of the adjustment nut and the top of the post off before installing the tool holder then it is less of a problem. If I also push down lightly on the post of the tool holder as I snug it up, that also helps. 

My point is that if you can afford a Dorian or Aloris, go for it. They are the top of the line, with fit and finish going to Dorian. Functionally, they are the same. If you cannot bring yourself to buy one of these name brands then I wouldn't worry too much about it. From what I've seen from other comments, Asian tool post owners seem to think their tool post works fine for them and that's good enough for me.


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## Charles Spencer

intjonmiller said:


> Now by requesting the total you are committing to the purchase. I don't care for that policy, but Shars always seems to discount it appreciably.



Yes, but that's ebay's policy, not Shars.  I dislike it as well.


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## intjonmiller

Charles Spencer said:


> Yes, but that's ebay's policy, not Shars.  I dislike it as well.


That's what I meant. Sorry I wasn't more clear on that.


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## 12bolts

I have a wedge type and think that the wedge is better





intjonmiller said:


> I recall seeing literature from Dorian or Aloris that confirmed that the wedge type is more accurate and repeatable, and I am at least 95% sure they also said it's more rigid.


However without knowing who wrote the  literature its hard to determine whos right.

Cheers Phil


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## BGHansen

Cadillac STS said:


> This topic shows up once in a while with very similar responses.
> 
> Is it too off topic to throw in here whether it is better to spend more for a Phase II, Dorian or genuine-authentic Aloris brand QCTP?  Or it the lowest price model just as good?


I couldn't find the thread, but someone was doing a very comprehensive study on the various tool posts and tool holders:  high-end vs. low-end.  I recall the run out numbers being very close on them all, Aloris or Dorian did not blow away Shars or CDCO.  For a hobbyist, low-end is fine, production shop with customers coming in looking at your equipment, might be worth getting the high-end.

Bruce


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## intjonmiller

12bolts said:


> I have a wedge type and think that the wedge is betterHowever without knowing who wrote the  literature its hard to determine whos right.


Do you mean the individual who wrote the copy for the catalog?? 

http://www.doriantool.com/tool-post-toolholders/

http://www.aloris.com/aloris_cat/31e970.pdf

Regardless, the point is that this isn't just a matter of tribal knowledge passed around users of internet machining fora. There's a reason Dorian doesn't make a piston-type quick change tool post (hint: their QCTPs are designed for CNC use as well as manual use). Aloris stopped offering theirs. The piston design predates the wedge type. Why would anyone bother to make a new type if the piston was sufficiently good? 

I've never seen anyone claim that the piston is superior, countless real-world users report that the wedge is superior, and manufacturer literature and pricing schemes (among manufacturers who offer piston and wedge types) both indicate that the wedge should be superior. How much more do you need?


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## Bob Korves

BGHansen said:


> I couldn't find the thread, but someone was doing a very comprehensive study on the various tool posts and tool holders:  high-end vs. low-end.  I recall the run out numbers being very close on them all, Aloris or Dorian did not blow away Shars or CDCO.  For a hobbyist, low-end is fine, production shop with customers coming in looking at your equipment, might be worth getting the high-end.
> 
> Bruce


https://www.hobby-machinist.com/threads/qctp-holder-review-part-1.52672/


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## mikey

intjonmiller said:


> I recall seeing literature from Dorian or Aloris that confirmed that the wedge type is more accurate and repeatable, and I am at least 95% sure they also said it's more rigid.



I've seen something to that effect, too, Jon. I only have wedge-style posts for my Emco lathe but I have both a wedge and piston post for my little Sherline and I have also found the wedge to be better in terms of how solidly the post holds. The way I tested this was to take a 0.050" deep cut (0.100" stock reduction) in mild steel and checked the tool height with my tool setting gage right after that cut; I repeated this 3 times for each type. The wedge style held the height every time, while the piston allowed a very small shift upward once. Not very conclusive, I will admit, but it was good enough for me to have more confidence in a wedge-style post.


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## jbolt

I think rigidity only starts to become a factor when you get to the lager end of the typical hobby size lathe which seems to be a 14" swing and up to 3 HP. Even then unless you are taking very deep cuts all the time I don't think there is a significant enough difference performance wise between the wedge or piston type. I think it would be more of an issue when you get into heavier machines of 5HP or more. 

I do like the way the wedge type feels when locking vs the piston. It just feels better but the testing I did comparing the two types didn't show a significant difference.

I have taken up to .35" DOC in aluminum and .25" in steel which is what I feel is the safe maximum for my machine. I don't do finish cuts at those depths so what is important to me is how the system work at finishing cut depths. 

The lathe I setup for the high school has a no-name import AXA wedge style QCTP. I find it is too loosely built and personally really awful to use but it works fine for the students. I had a no-name import BXA wedge on my old lathe and the quality was very close to the Aloris I now have on my new lathe so it can be luck of the draw on unbranded imports quality wise.


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## woodchucker

T Bredehoft said:


> I've used both, have no preference from experience.  Having said that, I note from the descriptions above, that while the piston type pushes the tool away from the post, putting pressure on the dovetails, the wedge type pulls the tool toward the tool post putting pressure on one of the dovetails (the wedge is not rigid,  u*sually formed sheet metal*) and the flat surfaces of the tool post, being somewhat more secure. This is from logic, I'd want to study both with indicators before making a positive judgement. In other words, which cutting tool would wobble more when clamped.



My chineese made AXA wedge is not sheet metal, it's a ground piece of metal.  If it were sheet metal, how would it hold at all.


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## Happycamper

http://www.cdcotools.com/

Wedge is $119


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## MrFixIt

Happycamper said:


> http://www.cdcotools.com/
> 
> Wedge is $119



And only $9 more than the piston so the purchase is a no-brainer factoring that. 

I have a Shars BXA wedge for the ATW. I can find no faults with the quality, looks to be a very well made tool.


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## woodchucker

Happycamper said:


> http://www.cdcotools.com/
> 
> Wedge is $119


I have a CDCO wedge (BOSTAR) quite good for the price.  I took it apart cleaned it up, greased it up, and put it to work.  Nice quality.


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## Bob Korves

woochucker said:


> I have a CDCO wedge (BOSTAR) quite good for the price.  I took it apart cleaned it up, greased it up, and put it to work.  Nice quality.


I have not allowed myself to spend real money on the Aloris and Dorian tool post stuff, and have a Phase II wedge set, that works great.  I have bought several lots of extra tool holders from various vendors.  The ones I got from CDCO are the best quality and were also the least expensive.  YMMV, one of the biggest problems with Asian import tooling is poor quality control and quality assurance.  Vendors also change their source of supply...


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## ddickey

Bob Korves said:


> I have not allowed myself to spend real money on the Aloris and Dorian tool post stuff, and have a Phase II wedge set, that works great.  I have bought several lots of extra tool holders from various vendors.  The ones I got from CDCO are the best quality and were also the least expensive.  YMMV, one of the biggest problems with Asian import tooling is poor quality control and quality assurance.  Vendors also change their source of supply...


Phase II is a step or two above the other imports. I have a piston one and appears to be of good quality.


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## 4GSR

woochucker said:


> I have a CDCO wedge (BOSTAR) quite good for the price.  I took it apart cleaned it up, greased it up, and put it to work.  Nice quality.


I recently bought one to replace my Aloris tool post on my 13" lathe I'm fixing to sell.  No way, I'm going to let go of my Aloris tool post!!!  I'll have to say, it's not too bad.  The only two con's I've notice is the slop in the wedges when you lock and unlock the tool holders from the post, and I have a older Aloris holder that is too tight for the dovetails on the tool post.  But that tool holder is not going with the lathe being sold anyways.  Bot overall, it holds the tool holders tight and releases them okay, too.

Ken


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## Sheldon0

I bought a Phase II BXA last year and the piston and wedge were the same price. I did pick a wedge and very happy with it. Put it on my 13" SB.


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## Doubleeboy

Bought a CXA Phase II a couple years ago, wedge style, it is a total piece of ****.  My no name wedge BXA on another lathe is worlds better.  Same could be said for the 10" Phase II rotary table, it leaks like a sieve.  No more Phase II anything for my shop.  I like the CDCO toolholders, except for the expensive shipping to west coast.


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## mikey

Miiikke,




... look into my eyes, Miiikke ... you're getting sleeepy ... buy a Dorian tool post and never look back ... buying no-name tools will shrink your Nards ... SNAP ... wakey, wakey!


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## whitmore

dlane said:


> Wedge, pressure on 2 Ddovetails, better than one



I agree with this (there are two surfaces next to the tool tip that have metal/metal contact force).
With the piston type, three surfaces are pressed into metal/metal contact, but #2 is the
(small) piston and #3 is an inch or two from the cutting edge.

There are lots of vibration possibilities (chatter being one) that can occur in a cut, and the
best acoustic coupling from the small tip to the large, soft steel (0r cast iron) parts will result
in the least oscillation, because sound energy will spread out into the acoustic dark spaces
instead of hitting an acoustic mirror and creating an echo chamber.

Similarly, a toolholder that engages the steel on one surface, with a  holddown screw,
(bottle type) isn't as good as one with two surfaces and two holddown screws.  

It'd be amusing to make toolholders that, instead of holddown screws, used a wedge
(like parallels) to fill the gap, so the tool had a complete over-and-under pair of
clamped surfaces.  In theory, the tool tip would be more stable that way.  
This is done, of course, for some cutoff tools.

The same theory (I'm a physics junkie) says that a collet-type boring bar holder
should be superior to screw-down toolbit holding.   There ARE square collet possibilities.


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## Catcam

T Bredehoft said:


> I've used both, have no preference from experience.  Having said that, I note from the descriptions above, that while the piston type pushes the tool away from the post, putting pressure on the dovetails, the wedge type pulls the tool toward the tool post putting pressure on one of the dovetails (the wedge is not rigid, usually formed sheet metal) and the flat surfaces of the tool post, being somewhat more secure. This is from logic, I'd want to study both with indicators before making a positive judgement. In other words, which cutting tool would wobble more when clamped.



I have a wedge style version and the wedge is definitely not "sheet metal"


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## Splat

Multifix. Only way to go. I got mine from Create Tool in central China after reading good reviews of them. Absolutely love mine. Went with an "A" series for my G4003G. Highly recommended.


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## Franko

I've had both. I'm nowhere near an expert, but as far as holding the tool securely and repeatable indexing, I could perceive no difference.
I'm not sure I understand why I would need to switch tools so they needed to index precisely as they were.
What I didn't like about the wedge is it tended to jam and make it difficult remove and install a new tool.
The piston type doesn't have that inconvenience.
I much prefer the piston type. I've had no issues with piston AXA I have on my 12x28" lathe.


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## darkzero

I've always wanted a MultiFix type TP. At the time for me they didn't make sense for me. The holders, although made in China, were expensive & not readily available. I got a good deal on a brand new Dorian SQCTP so I went with it, no regrets though.

Wedge is superior to piston. I personally am not a fan of piston. My Dorian & my previous DTM wedge TPs have never jammed or bind up on me. The locked up feels great, much better than a piston. If a wedge TP does that, it might just need to be disassembled & given a good cleaning. I don'tbrecall having that problem with my China wedge that I had on my old mini lathe either but I only had it for 8 months.

The reason why wedge is superior to piston is rigidity. A piston pushes the tool holder outwards so it registers on the dovetail. A wedge pulls the tool holder in against the body of the tool post & is what makes it more rigid. There's a reason why Aloris don't make the piston style anymore as well as the other name brands. Dorian used to make a cam type TP, but it too pulled on the dovetail instead of pushing it out. Pretty much only China still makes the piston type from what I have seen. But one thing I've noticed is that the piston type is not very common in the big sizes. Maybe a reason for that IMO but maybe not.

When I took a machining course with my lil brother at the local CC, most all their lathes had piston type tool posts. With heavy cuts or vibration the pistons actually came loose sometimes. Had to keep your hand on the TP handle when that happened. The TPs could have just been worn but it tended to do that on multiple machines.

With smaller hobby lathes, the difference may never be noticed. Nothing wrong with a piston in that case. Wedge doesn't cost much more so if buying for the first time, might as well just get the wedge IMHO.

EDIT: Oops, sorry for repeating a bit of which most have already said, I didn't read the whole thread before I posted.


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## Splat

I forgot to mention that yes, I too had jamming problems with the wedge type. Yes, the rigidity was there but so was the aggravation I got when changing tooling.


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