home made large bore indexer

[CRM]

I'm not sure if I've picked the correct forum to post this question, so please move it if need be.
I have retrofitted a SWI Trak DPM to Centroid ALLIN1DC control and want to add a 4th axis indexer to spline shafts. Here's the twist: I need to be able to pass a 2" diameter shaft thru the indexer bore. I don't need simultaneous rotary/linear motion, I will be using the 4th axis for rotary positioning only.
I have a Cushman Super Spacer with an 8" 3-jaw chuck that would be ideal to hold the workpiece, the challenge is how to drive it with a servo. My thought is to use a HTD pulley set and belt just like the drives for the linear axis ballscrews. I recognize there won't be any mechanical gear reduction normally supplied by the ballscrew. Has anyone built an indexer similar to this, and if so, what is the minimum ratio required to achieve typical indexer resolution? I assume the higher the ratio the better, and I was hoping to find a source for HTD pulleys at least 6" OD, preferably closer to 8" with a tooth count of something above 144. They don't seem to be available in the 5mm belt pitch size (the size I was hoping to use). I would not be opposed to having a pulley custom wire EDM'ed but, again, I am having trouble nailing down accurate geometry to draw up a CAD model to give to a shop to make one. Anybody who can point me to that data would be my hero.
I envision replacing the master index plate with that pulley, and driving it with a servo with the smallest available pulley on it's output shaft. An air cylinder could be used to actuate the Super Spacer's spindle brake and activated by a spare M code. ( Actually, I would probably set it up as spring applied, air cylinder release for failsafe operation.)
Does this sound feasible? If you read between the lines, I'm trying to do this on somewhat of a modest budget, especially since I already have the Super Spacer and the alternative is a rotary table in the 210 mm platter class to get a thru bore over 2.000". I haven't seen any of those go for less than about $4k used on auction sites...too rich for my blood at this point.
I welcome any helpful data or component leads anyone might be able to give.

[xr4x4ti]

Dean,

I don't think it is worth the effort. Watch the local auctions (you are pretty close to me) and look for a CNC indexer. I got an 8in for under $400. It was to big for my application, so I sold it and purchased a really nice 6in unit.

Check out my video where I used the 8in unit.



I have yet to actually hook it up to the Allin1DC. I just have the program pause and I hit the next button on the indexer. My goal long term is to use an M code to drive it automatically.

I am making CV axles for my AWD Mustang Conversion.

Tim

[CRM]

Tim--
What was the thru hole diameter of your 8" indexer? I have to be able to pass a full 2.000" diameter. That doesn't happen in any indexer I know of until about a 210 mm platter size (equiv to a Haas HRT-210) I bid an auction for a Haas HRT-210 up to $2,300 (with buyer's premium and tax that was about $3k) and lost out. Previous auctions for a similar size indexer also closed at the $2.5-3K range, so I'm not finding the deals that you are, apparently. I've been watching for about 3 years now. I also must have a model that uses a brushed DC servo, as I WILL be integrating it as a true 4th axis on my Centroid.

A note about the splining in your video: I couldn't tell what you were using for a cutting tool, my suspicion is that it wasn't a proper involute spline cutter. If so, that would explain why you overshot your depth when you calculated your size over the pins. My first splined shafts were done with a carbide end mill set to cut at 45 degrees polar to the shaft centerline. It worked, but it's not a true involute spline profile (it was simply a 90 degree "V"), and it doesn't spread the load evenly to the female spline profile. I have since invested in the proper spline cutting tools (Vardex makes an inserted cutter body that accepts a range of inserts to cut every diametrical pitch or module used in the automotive industry, it cost me 600 bones for the body [which holds 4 inserts], and inserts were sold in packs of 10 for 78 bucks an insert [$780/box]--ouch! At least you get 3 cutting edges per insert.) I get very repeatable results setup to setup, so at most I go around the shaft twice on the first piece. Every subsequent shaft is dead-on going full depth the first time around.

[xr4x4ti]

Dean,

I am making true involute splines. I am using tools from https://adventtoolusa.com/. The holder was under $200 and the inserts are about $45 and you get two cutting edges.

In the video, I would using a YAUSA SUDX-220. It looks like that has a 42mm bore, or 1.65in. I guess that would have not fit your needs.

I actually wanted a smaller unit, so I sold that (Made money:) and now I have a SUDAKOMA RZ-160. This has a controller that is MUCH easier to use, but it does use an AC servo motor. So, if I ever want to do a true 4th axis, I will have to swap motors.

But, for what I want to do, splines, etc, the included controller is pretty good and it can take digital inputs from the Allin1DC and thus an M code could be setup to tell the controller to move to the next position. I got the whole thing in great shape for under $500 and it only weights 80lbs, vs 220+lbs for the YAUSA.

If you are going to not use the controller anyway, don't look for the HAAS units, they go for a premium.

Tim

[xr4x4ti]

This is probably not large enough, but it is local.

https://www.ebay.com/itm/155749911356?m ... media=COPY

Tim

[CRM]

Yeah, MachinesUsed had a RZ-160 up for auction a couple months ago. I was excited because it listed the thru bore at 2.4 inches or something like that with only a 6" faceplate. So I went over to lay eyes on it myself. NOPE. The thru bore was way smaller than 2" (as you know). I only stated the Haas HRT-210 because I have a HRTA6-A6AC (dimensionally equivalent) for the VF-3SSYT here at work and am familiar with the model number and dimensions.
I think I did run into the Advent Tools cutter in my research, but decided I wanted more teeth to keep the feedrate up when cutting. Honestly, not positive on the reasoning at the time to go with the Vardex over the Advent. But it is a damn stout cutter body with a stable insert pocket. Plenty satisfied with the tool rigidity and accuracy.

The size thing is one of the reasons I am leaning toward the Cushman Super Spacer conversion. It's already a 3 jaw chuck (required to hold the axleshafts on the necked down diameters behind the splines) and it is relatively compact and lightweight...even after accounting for adding a servo. The only hiccup is calculating the correct pitch diameter and circular pitch for a pulley that big. I suppose I could try to contact Gates and see if someone will entertain my questions.