A few weeks ago now I finished a quick change toolpost for the Schaublin.
The design is based on Andy Lofquist’s MLA-23 toolpost. Andy is the man behind the wonderful Metal Lathe Accessories kits (http://www.statecollegecentral.com/metallathe/). While I’ve never ordered any kits from Andy, I’m told that they are very high quality and are exceptionally thought out.
After quickly considering a Tripan toolpost and changing my mind after I saw the prices on those I ordered a set of drawings for the MLA-23 toolpost. The original design is for 9″-12″ swing lathes. The Schaublin is an 8″ swing lathe. After drawing up the original toolpost in Fusion and drawing up the Schaublin cross slide it was evident that it was too big. I decided to design a scaled down version, making some changes along the way.
The largest change is in the dovetail size and the shape of the body itself. I wanted something that would match the Schaublin’s size, but also look, so I manufactured the body out of round material instead of square. The toolpost is optimized for 1/4″ HSS tools, but 5/16″ will fit.
The internal workings are that of the MLA-23 toolpost. The design is exceptionally rigid and works very well. It is also a wonderfully simple in design. Part of the reason I really like this design is for its simplicity. I believe the best design is one that doesn’t allow you to take anything away. This design, in my opinion, is one of those designs.
Some people don’t like that the toolpost doesn’t repeat in angle position – that is once you loosen the locking handle you completely loose the rotational position of the toolpost. This is a downfall of the design if you truly need rotational position repeatability. When I work in the shop I’m constantly moving the toolpost around to allow for tool clearance. So much so that I made a handle for my Aloris clone on my 10×18 lathe a number of months ago. I do have provisions in the design to allow for graduations on the base to allow for visual rotational positioning. We’ll see if I add it.
The build was interesting and fun. I learned a number of things along the way including how to cut dovetails on the shaper. It took a bit of time, but it reaffirmed the very useful nature of having a shaper in the shop. Instead of waiting for a dovetail cutter I could grind up a simple tool and cut nice dovetails, at any angle, and get a super finish. I’m told you can build the entire toolpost with a lathe, but there is a fair bit of milling work so even a mini mill would be a huge help.
Since the design borrows heavily from Andy’s design I don’t want to release drawings. What I’m planning on doing is forwarding a set of drawings to Andy to include with his prints if he is interested. So if you want to build the smaller version, which is a perfect size for the mini lathe, send me an email and I’ll try to get you a set of drawings.
I made a build video of the entire toolpost in montage style format as well.
2 thoughts on “Shop Made Quick Change Toolpost”
I really enjoyed your video about the making of this toolpost. Beautiful machining blended with great video nicely edited. Bravo, and now I’m a subscriber.
The MLA design is the one I fancy making for my lathe (an ageing Viceroy) but there is an aspect of the design which is a little puzzling for me, so I have a question for you which I hope you might be able to answer for me.
I love that the toolpost is positioned and locked by a single handle, which pushes down the block onto the cross slide at the same time it pushes down the cone onto the taper to open the slit and engage the dovetails. Sounds straightforward enough, but does this not make it an exercise of very high precision to ensure that both the dovetails of the toolholder and the seating of the block onto the cross slide are provided with sufficient pressure to be properly stable?
And does it mean that the force of the tightening bolt is effectively shared between each mating surface – and therefore halved form what would be achieved by having the same bolting pressure applied to just one or the other?
I know I’m just overcomplicating it because it obviously works very well for you and many others, but I just wondered if you’d considered this.
Keep up the good work,
Hi Stephen. I realize it’s been a long time since you posted, and I forgot to answer your question. The design does require a good fit between the holders and the post – I believe Andy said around .003″ is his recommendation (ie the holder shouldn’t be any larger than .003 than the body). I didn’t find it overly challenging to hit this tolerance, and I am certainly no master machinist so if I can do it you certainly can. Regarding the rigidity of the post, I find it very good and I know Andy uses his toolpost on his Southbend daily. In some ways from a rigidity standpoint I think it actually beats an Aloris Wedge style. If you’ve ever taken apart an Aloris wedge AXA tool post you’ll notice how little material there actually is in the toolpost block. Regarding the forces – I should draw up a free body diagram, but the bolt is only part of it. The contact forces are actually fairly high but I wouldn’t be able to say if they are better or worse than an AXA without doing some more work. I really appreciate the comment and support!