Need a positionally rigid 8-space indexer... make or buy?

Howdy again.

An operation I need to do in some quantity requires an 8-hole bolt pattern on about a 12" diameter. With that much lever arm acting on it, I can feel play in each position of my Hardinge copies, which work with pins dropping into holes. Looking at the Super Spacers, they appear to use notched index plates rather than holes/pins like the Hardinge.

So two questions. First, does the Super Spacer design generally have a more rigid lockup than the Hardinge design; and if so, do you have any experience positive or negative with the copies like the Phase 2 or do I need to spring for a Bison..... and second, is there a simple design for a shop-built 8-space unit that youve seen or built?

I don't need it to operate quite as fast as the Hardinge, but I do want an indexer here; if it gets into being finicky I might as well just do an X/Y extrapolation and do the holes that way. I'd really rather not as I've got a bunch of these to do.

As always, your experience and guidance is hugely appreciated. Getting tooled up for this suite of castings has been kinda epic but I'm finally to the fun part where the payoff starts in. It's ongoing work so if the solution is a $3000 Bison Super Spacer or the like then that's ok; but if I can build something, so much the better. I just can't think of a design that is tight and true in the Z axis yet easy to turn and then locks into position very securely.

On that note- the bolt hole pattern is comprised of 1/2" drilled holes in the one part and corresponding 1/2" tapped holes in the mating part. So the forces at play are not large. Material is cast aluminum. Finally, whatever I buy or make needs to be as short as possible in Z as I'm about maxed out on my mill with the Hardinge.

Long Tom said:

if it gets into being finicky I might as well just do an X/Y extrapolation and do the holes that way. I'd really rather not as I've got a bunch of these to do.

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Yeah, but .. the machine dasn't need as much scarce Z, doesn't get any tired'er, use up more tool-wear budget, nor slow-down terribly. More wear on it to do what the Hardinge has been doing, yes. But stiffer workpiece, so..

Also doesn't need more tooling spend in the direction of reverting it back to how manual mills had to do it before being able to directly respond to math calculations.

Have you tried that for cycle time and ability to sustain spec? Scrap stock should tell the tale just as easily as risking a casting. Will simpler loading/unloading buy back some time?

It's hard to beat the simplicity and rigidity of a simple direct indexer using a taper pin in eight tapered holes. Also, you can shop-make one very, very shallow.

What about making drilling jigs? .they're a 1 off job on the rotab etc, etc and as long as they're right mistakes can't be made.

No on the Bison for accuracy. I have one I bought new (from when it was called Toolmex), repaired it twice and now consider it worn out and we use it only for less demanding jobs.
Hartford or Yuasa indexers are way better. I understand the Yuasa is a copy of the Hartford and use the same indexing plates. I have 2 old Hartfords i bought used and they are built like the proverbial brick outhouses, and lock into position super securely. Not as fast as the Bison, and take 2 hands compared to one, but positioning accuracy is better. You can take the chucks off and make your own fixtures.
I can go into great detail later if needed, but this is the short version of what I've experienced.
Even better is the Erickson style air indexer. they are available in large and small size. We have a couple of both and use them on CNC and manual machines, when there are more than a handful of parts on a manual job we rig up an Erickson.

Could a surplus 8 position lathe turret be adapted without using up too much z? I would assume they would to lock with excellent precision and strength.

If you roll your own, a curvic coupling would provide excellent precision and rigidity without much Z.

Arrow Gear Products - Curvic Couplings

I'd get a good Super Spacer for that job for this reason- when the job is done, you have a nice Super Spacer.

Second Yuasa. I used to have had a regular spacer (no handwheel) that was quick to index and locked up tight.

They're just too handy to live without imo- I put them higher on the list than a rotary table or dividing head. Get a tailstock too, you won't regret it.

We had 3 Hartford Super Spacers in the last shop I worked at. They were the best and most solid locking indexers I've ever used. I couldn't detect any slop at all in the indexing mechanism of any of them by hand. Never bothered to put an indicator on them though.

sfriedberg said:

It's hard to beat the simplicity and rigidity of a simple direct indexer using a taper pin in eight tapered holes. Also, you can shop-make one very, very shallow.

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I'd love to hear or better yet see more about this. Thank you!

+1 for an Erickson air indexer. I have a pallet of them bought on Ebay for under $500 for all. They are simple, rugged and fast.

For a 12" circle I think you'll want the big size. I think the bigger was the 600 or 800 model? The smaller is the 400 I think.

You know you can buy a used VMC for what a good super spacer costs right?

This will sound silly but can you post a picture of what it is your trying to do? I basically spend 1/2 of my time building custom fixturing or workarounds to increase productivity while reducing handling time. Sometimes though if what you have works just as well

+2 on the Erickson air indexer. a model 600 should be about the right size. the standard index plate is a 15 deg, same as a super spacer, but there is a stop that can be adjusted so it will skip so notches so you could have it just do the 45 deg. moves for you at a push of a button. If buying one make sure all its pneumatics are there. I have seen ones on ebay without its air brains. I just recently got mine up and running with a custom 14.4 deg index plate I finally had time to make. it was to replace using a super spacer to do 2 sets of 25 threaded radial holes on a set of parts. here's a clip of it in action Erickson model 6 speed indexer - YouTube the table jogs over to actuate the index button. I picked up this indexer about 3 years ago for less than 200$

Whysosharp said:

This will sound silly but can you post a picture of what it is your trying to do? I basically spend 1/2 of my time building custom fixturing or workarounds to increase productivity while reducing handling time. Sometimes though if what you have works just as well

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Yup, it might be better to make a drill fixture plate, coupled
with a multi spindle head, and do all 8 at one time.
Used Machinery & Industrial Equipment | HGR Industrial Surplus

BX827: ETTCO 1HP MULTI-SPINDLE DRILL PRESS - McKean Machinery Sales, Inc

Limy Sami said:

What about making drilling jigs? .they're a 1 off job on the rotab etc, etc and as long as they're right mistakes can't be made.

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Mention of "extrapolation" gave me the impression it was a CNC rig, commanded positioner, and goaled towards hands-off runs.

Faster drill jig on drill press is cheating!

That wants one of those smelly and sweaty "humans" involved, and wuddn' yah know it? They not only want a paycheck, they'll be after yah for something more challenging and profitable to do soon as these parts have been run!

Pesky buggers..

Your clones don't sound like "Hardinge design" if they have straight pins.
Pretty sure the ones in mine (actual Hardinge) are tapered. At least they get tighter when you press them back hard as opposed to letting just spring pressure do the job. This is in relation to the HV4 series.

Hardinge dividing heads (actual 5C DH's) have tapered pins and the ratio is 4:1 so they are about as fast as an indexer. (1/2 turn per position for 8 positions) Nose will take and Hardinge ID or OD fixture tooling. Probably not ideal for your app, though. A direct plate, even shop made, would seem to serve you fine; as others mentioned.

smt

sfriedberg said:

It's hard to beat the simplicity and rigidity of a simple direct indexer using a taper pin in eight tapered holes. Also, you can shop-make one very, very shallow.

Click to expand...

Long Tom said:

I'd love to hear or better yet see more about this. Thank you!

Click to expand...

Well, a shallow direct indexer is pretty much an index plate on a bearing with some way to mount the work.

I'm going to assume your parts are mostly "flat" and could be clamped to a plate/fixture. Your direct indexer needs a base, which mounts to the machine table, and a top, which bears on the base and to which the parts get clamped. If this were 1950, the base would be a cored casting to give it some depth without excessive mass. Today, you might make it from 3/4" or 1" mild steel plate, with faces cleaned up parallel.

For lack-of-slop, you want a tapered bearing between the base and the top. This could be a nice tapered roller bearing, or just tapered stub on the top riding in a tapered hole in the base. If the parts are heavy, I'd probably put brass or bronze shoes from shim stock between the top and base out near the working diameter to support the top. There are lots of other alternatives, of course, including machining a circular V and V-way, as used on some rotabs. Having a taper of some form (and if you use a roller bearing, excellent shaft/bore fit) is important for taking out the slop and locating the top definitely.

For your top, drill and tap appropriate holes for work clamps. Or, if you start with a thick plate, cut appropriate T-slots (and then flatten faces again). Additionally, you need to drill and ream for taper pins the eight index holes. Do this with the top and base assembled at the correct separation. I.e., while any shoes or shims are in place. Since your objective is to drill parts, not make indexers for sale, I would drill and ream eight different places, instead of trying to re-use one hole in the top for all eight index positions in the base. The danger of re-using one hole is that you will eventually ream it larger, so that a taper pin no longer fits the previously drilled/reamed holes correctly.

Number the holes in the top. If you're feeling fancy, mount a sheet metal flap over each hole in the top to keep chips out.

Operation is simple. Pull the taper pin, rotate the top, drop the taper pin into the next numbered hole. Make sure you didn't catch a chip in the hole.

If you plan to make thousands of parts with this fixture, the index holes should probably be hardened to avoid wear. However, the virtue of using tapered pins/holes is that even a noticeable amount of wear can be taken up without indexing slop.