Putting together an Indexer...Coupling?

[jim_stadtlander]

I am wondering if there is a place get adapters/couplings that go from the keyed motor shaft to the lathe shaft which has threads. Or, something that would enable lathe accessories to be mounted directly to the motor shaft. Perhaps I am not knowing what to call this part to be able to find it anywhere?

Dirk Dunham had a post awhile back that mentioned how he put his together, but I am not able to figure out that connection between the motor and the lathe. Spider Coupling? Not sure how that works, and would it work in this situation...if this is even the connection he was refering to.

It seems like somebody would be making this out there, instead of having one fabricated. Any suggestions here will be greatly appreciated.......Thanks, Jim

[Brady Watson]

You can buy machinable shaft couplers from McMaster.com - and yes, you will most likely have to have them machined to fit your shafts, as they are odd metric sizes, no doubt. Another solution would be to make a synchronous belt-drive with 2 pullies, one for the motor & one for the lathe. This is what I have done on my 16" dia indexer. Since all lathes are different, you'll have to do your own homework on what will work & what won't.

-B

[jim_stadtlander]

Thanks Brady ........ I was thinking about keeping it set up with a belt and pulleys, both at the same ratio, but haven't seen anyone doing it that way. Do you ever have any problems with the belt system slipping or anything else that would get the motor out of sync with what it is turning? .........Jim S

[wooddr]

Jim,

On page 1147 of the Mcmaster.com web site those are the type of connectors that I used. I also used a simple spider type connector that I got at Grainger's. I put a simple hose clamp in the middle of the spider connector to take out some of the slack. I don't think I would try a belt type connection, I am pretty sure you will experience major slipping.

Hope that helps

Dirk

[steve4460]

Jim
Check out this http://www.grizzly.com/products/g3158 you might find what your looking for .

Bot on

[Brady Watson]

Dirk,
You will not get slipping with a synchronous or toothed belt. Chains and gears are too sloppy for indexing, and direct drive can take up too much room, making the indexer much longer than you might want it to be - although it would be a zero backlash solution if it fits in the space allotted. The belt solution is also zero backlash.

Just to add some more tech info: Alpha motors have a 14mm shaft & PRT/PRS Standard motors use a 1/2" shaft. Check with digital calipers to be sure before ordering couplings or pullies.

-B

[jim_stadtlander]

Hi Dirk,
So if I am understanding this correclty from reading your old post and the referal to these parts, you actually have two different couplings that are attached together? One coupling is attached to the lathe so then the spider coupling can be hooked to it?

Brady,
My shaft is 18mm on the motor, and my lathe is 1" OD 8TPI Left hand. It kind of looks like I can't get the 4 step pulley off the lathe, so I might not be able to put on a synchronous pulley in it's place, but I do like the idea of not taking up that extra 10" for a direct hook-up. Makes me wonder about hooking up right to the motor and by-passing the lathe. I wonder if the sideways strain from heavy blocks of wood will strain the motor (instead of the lathe body carrying the weight).

Jim

[Brady Watson]

Jim,
There is absolutely nothing wrong with connecting the stepper to the existing motor. In fact, I believe this is exactly how Wayne Locke did it years ago on his PRT. Unless you bought a SB indexer, one is on their own to figure out just exactly what will & won't work with their particular setup. I had a machinist friend of mine bore & broach a keyway into both pullies for both the Grizzly lathe I am using as an indexer and the pulley for the original Alpha indexer motor. The most important thing that you need to watch is backlash on an indexer - otherwise, you will have slop in your turnings & that just isn't very much fun
I've since 'aquired' a 100:1 harmonic drive motor & driver with zero backlash...so I might have another pulley machined by my buddy...not enough hours in the day!

-B

[wooddr]

Jim,

I made a reverse thread adapter coming out the back of my Harbor Freight lathe. The first coupler I used was a two piece spider coupler to hook the motor and the adapter together. There was too much play in it so I replaced it with the type of coupler I mentioned above.

Dirk

[jim_stadtlander]

Thanks to all for the different approaches to the same problem with the coupling.

Brady,
In some old posts you mentioned Deskproto software with regards to rotary Indexing. Do you still favor that over Artcam for doing fully sculptural pieces. Or has Artcam updated to be more user friendly for four sided objects. Thanks, Jim