Rotary Spindle Adapter Plate

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RSAP Photo
RSAP Photo1920×2560 651 KB

Rotary Spindle Adapter Plate Album

I love my Avid Rotary Kit. I use it as much as any other aspect of my Avid setup. It’s been very dependable and has really expanded the scope of what I’m able to do. I’ve done conventional woodturning for over a decade and still do quite a bit on my Robust American Beauty lathe.

The chuck of the Avid Rotary kit has been problematic for me. Mechanically it’s sound, but it has a lot of drawbacks that are evident to woodturners. I’ve tried to work around the drawbacks, but all the solutions have been kludges. I was talking to Jim Neeb about this, and we kicked around potential permanent solutions. Jim felt the best solution would be to put a ‘lathe spindle’ where the chuck is which would allow us to use all of our lathe accessories as we do on our conventional lathes. Brilliant!

Some designs were made, followed by some prototypes that Jim and I tested on our own lathes. We’ve come up with a rotary spindle adapter plate (RSAP) that you see pictured above. I’ve also created a Google Album that shows the RSAP closer, along with different use videos. Various measurements have been taken to give an idea of performance characteristics. In short, you give up a little precision and get a lot of versatility, particularly if you are already a wood turner.

Basically, what you do with this piece is remove the Avid chuck (three bolts) and the chuck adapter plate underneath it (seven 6mm bolts). The RSAP mounts to the planetary gear box (Avid calls this the reducer) with those same 6mm bolts and its alignment pin. The RSAP provides a standard 1 1/4 x 8 TPI spindle thread.

For reference, runout on my Robust American Beauty lathe spindle collar is about 1 thousandth. When I mount a Beall collet holder on it with a 1/4 inch rod, runout is about 1 thou.

The runout on the Avid reducer collar is about 2 thou.
Mounting the RSAP on the reducer gives RSAP collar runout of 2.5 thou. Measuring runout with the Beall collet holder gives runout of 8.5 thou (see video). So, on the one hand, runout is quite a bit higher than my lathe, but overall that kind of runout for rotary CNC work is quite okay with me.

The versatility gives the ability to use a collet chuck, all my other lathe chucks, and spindle plates (videos are also in the album). I can now safely machine right up to the edge of my work. Fixturing to round parts is much more secure with a lathe chuck, particularly in expansion mode. The other nice thing about this is that you can take the piece from the CNC and put it right on the lathe for other work (like hollowing out a bowl). Just unscrew the chucked piece from the RSAP and mount it on your lathe spindle.

If there is any interest among Avid users, please let me know. We can explore having a batch of these made which brings done the individual part cost substantially. I’m also happy to provide .STEP and Fusion 360 files to individuals on request.

Scott

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this is an excellent idea. I have a cupboard-full of chucks/jaws and accessories

I’d be happy to be a part of a batch build, but my Nova Comet II manual says that the spindle thread is 1"- 8TPI so I may have to look at getting something made specifically for the comet chucks. I’ll have a look when I get down to the mancave

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Yep, I recognized other folks might have that size since it’s quite common. Nova (and others) make adapters like this which will allow you to mount a 1" chuck on a machine with 1 1/4" threads.
There might be other solutions too.

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Count me in for mass production then.

If there’s not enough interest for a production run, I’d appreciate the F360 file and I’ll see if I can get it made here in Aus.

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Absolutely. I can also make up a F360 version with 1 x 8 TPI threads as well.
Message me with your email. It’ll be easier that way.

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A small production run of 5 Rotary Spindle Adapter Plates has started. Two are left available. $185 plus shipping (totally the cost of machining).
Message me if you want one.

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I would be interested. Would also love the fusion file. I might machine one up on my manual metal lathe and mill.

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Information sent Tim.

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I love this idea! I too have a wide variety of 1-1/4" 8 TPI chucks for my manual lathe that would be great to use on the Avid Rotary.

I’m wondering if another option might be to make a 1-1/4 x 8 TPI adapter that would allow one to mount an conventional lathe chuck in the Avid chuck? it would reduce spindle length but may be another option.

Sign me up for one if you have a batch made. I’d love to have one!

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These have all been sold.

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Mine has arrived here in the arse-end of the world - thanks @grossmsj for organising this, and @jjneeb for his input.

Beautifully made, quality part.

@Eric ,Avid should adopt this and supply it as standard (or as an add-on) - it opens up a range of additional possibilities on the rotary.

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What am I missing here? is it not just an adapter to screw on a different chuck?

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The Avid machinist chuck has a place. If you are using it to hold 4x4s or 2x4s, it is all you need. You put your wood on it, do the work, take the piece off, and saw off the chucked end. A machinist can put a chunk of metal in there, clamp it like hell, and use a parting tool to separate the piece at the end of the job if you are doing it on a mill. Some machinist chucks have replaceable jaws, but the version of the Sanou chuck on the Avid doesn’t let you get soft jaws or any other jaws.

The parts I’m making are different in a lot of ways. I want to machine the entire piece. The wood is expensive and the parts I’m turning need to be finished right up to the end. I usually start with a piece that’s clamped internally (into the hole on one end). With the RSAP I can choose from any of the chucks I have at hand that are best-suited to holding the piece. Lately I’ve used the Beall Collet Chuck with internal expanding collet. The collet expands very securely because it contacts the wood on virtually the whole diameter of the piece. It also leaves the end totally exposed to the spindle and bit without any concern of running the bit into the chuck jaws. It also doesn’t leave any marks from clamping. The whole piece is turned right up to the end, including putting a chamfer at the end of the piece. It is virtually completely done. I can just loosen the piece and remount it on my other lathe for sanding or any other little details because everything remains concentric. You could do this with any chuck, particularly if it has long jaws. You could also mount a faceplate.

My frustration with the machinist chuck was two-fold. First, it’s nearly impossible to machine to the end of the piece because the jaw fingers are short and it’s hard to avoid the jaws with a bit over 1/4". I had to sort of slide it out toward the end of the jaw. When that happened there is only a very small surface holding the wood. It’s only mating to maybe 20% of the wood diameter. Opening the jaw would compress the wood in those areas and I kept finding the piece loosening during the job.

So, it’s true ‘it is just an adapter to screw on a different chuck’. But for many folks, it will let you work in a lot of different ways you just can’t do with a machinist chuck. One knows if they need it or not. If you don’t, that’s fine.

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Here’s how this looks operationally. The 3x3" piece of mesquite was milled on my vertical table, putting hollows in the ends to accept a CrushGrind mill mechanism. It was then mounted on the rotary with the collet chuck. Three Fusion toolpaths cut the shape, and a Vectric toolpath added the texture and beveled the end by the tailstock.

Collet Chuck
Collet Chuck1920×1440 343 KB

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Any plans to do another batch? I would love to get one.

If not if you wouldn’t mind sending me the file I will look into what it costs to get one machined.

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Message sent @greg.obj

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Thanks for the detailed explanation, I just wanted to be sure I wasn’t missing anything. I do not have a wood lathe, but now I understand that you could have on hand several different chucks that this adapter will let you use…

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i received my RSAP last week and it is a very well made piece. The machining is fantastic. I haven’t had a chance to use it yet, but I really liked the idea and had to have one.

I have a wood lathe and have made a significant investment over the years with Beall and Nova chucking systems along with their various jaws. Having the ability to use tooling that I already own on the rotary axis is a huge advantage in my opinion. It really opens up the possibilities for work holding options.

If you have an assortment of traditional threaded lathe chucks and jaws, I would highly recommend getting this adapter.

@grossmsj, If I had one suggestion that may help the overall community it would be to have an option with a 1"x8TPI option as well. When I started in lathe work years ago I used a Jet Midi lathe that had this thread and Nova at that time didn’t offer the adapter insert. This option may make it more accessible to those with 1"x8TPI chucks that don’t have the built in adapter.

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would be to have an option with a 1"x8TPI option as well

That’s a good suggestion Brian. @Bernmc also asked for this.
Honestly, the root problem is sticking my neck out financially to have a run of 4-5 made. I have no way to know if I’m going to sell those or not. I’m not making anything from these, so losing money is only downside. One could always have a single made, but the cost is a LOT more getting just one. My approach now is to commit to a batch once I have three committed buyers.

I’m glad to see you and Bernard are happy with the RSAP!