Finally adding an indexer/lathe

[bruce_taylor]

I have been wanting a lathe/indexer for sometime now. I have acquired a few prt alpha motor/driver's just for this. I will also be adding a second z assembly with 16" of travel I will be installing it at the end of my 5x10. I really like the lathe setups I've seen on the forum and I'm looking for a suitable lathe to convert for this application. A few questions, does the belt drive work well or would a metal chain drive work better? What other resources are available?
I read through the wiki but can't find alot of information on this. The forum is a great help. Thanks in advance. I know I will have more questions as I progress.

[Brady Watson]

Bruce,
I am assuming that you scooped up the 3 AS911s that were for sale. These are direct drive motors, and while reasonably powerful and fine for most operations, they are lacking in torque & resolution for what you want to do.

First, to the best of my knowledge, ShopBot never shipped a 1:1 Alpha Z axis with greater than 6" of travel. This is because the motor is under tremendous strain as it overcomes the force of the spring tension on the Z at lower positions of travel. Second, for an indexer you want a stepper with at the very least a 10:1 ratio reduction. You might be OK with very small (2 or 3" dia max) parts with the 1:1, but as the diameter increases, you will quickly see the need for higher resolution.

You can of course, make belt reduction boxes to increase torque and resolution for either or both of these applications...or keep your eyes peeled for the right motor for your application.

-B

[bruce_taylor]

I picked up a asm98aa that i planned on using for the indexer/lathe setup.
I did pickup the 911's also, One to replace one thats been giving me a little noise and vibration and adding the extra z I wont be using it at full extension but hoped it would give me a couple extra inches on the lathe so I could mount it below the top of the table. I am planning on doing a geared reduction and wanted to get some opinions on what might work best. I'll know more when I get my hands on it in a few days. Thanks for the reply Brady

[steve_g]

Bruce

I can only second what Brady has said about using a direct drive motor in an indexer... I tried using that setup to engrave bracelets with only a degree of success. You never knew when the cutting forces would overpower the motor spinning it wildly and ruining the part. a subsequent 10:1 motor solved that issue.

Steve

[myxpykalix]

Steve,
The 2 pictures you posted above, is that something you put together? Was there more information that accompanied the pics? I'd like a little more detail as that looks like something i'd like to make for my granddaughters.

Are there standard sizes made? Thicknesses?

[steve_g]

Jack:
The images are posters I put together for last years Austin camp. I make two styles of bracelets, one style uses a blank precut on the ShopBot and then finished on the indexer, the others are basically freeform that are just rounded over on a table router after they come off the Bot.

90% of the commercial bracelets I checked (I like to make up stats) had an internal dimension of 2.625", that worked for my daughters so I never made other sizes. However I will say that at craft shows 51% of potential buyers were larger women who were unable to find commercial ones to fit them. I fooled around with two part bracelets that were held together with very small rare earth magnets. The addition of four magnets made the cost unattractive. Thickness is all over the place and girls like to wear mixed sizes stacked up.

My experience taught me that I needed to make my bracelet blanks of laminated woods if I didn't want them to break when dropped. After laminating, blanking, indexing and finishing, I found that I was too proud to sell them for what Chinese imports could be bought for.

If you are still interested in making some, I have attached a file of some indexer blanks and some free form styles. Some of them have napkin rings cut out of the interior of the bracelet to make better use of the wood. The problem with napkin rings is that someone always wants a dozen of one style and you find yourself making more napkin rings that you priced too low because they were essentially free or made from scrap.

A note of caution here... I use a table router to radius the inside edges of the bracelets. About 9 months ago I experienced my first digital accident... Find a way to hold them other than by hand.

I hope I have answered your questions... Most of my indexer files were personalized ones with a small ornament, but If you want to see some of my indexer files, let me know.

Steve

[donclifton]

Bruce, I have done two lathe type indexers one for a shopbot friend in Atlanta and mine which is a shopbot style clone. I live in Port Orange, Fl if you would like to see the way mine was done.
Don Clifton
Dclifton2@cfl.rr.com
4axiscnc.com

[myxpykalix]

Thats some good info for starts. I'll email you direct because i'd like to see some of your files and try to make some for the grandkids. I'm just starting to be able to get back in the shop but i won't be doing any big projects so some of these small things might be perfect.

I'll email you with some questions

[blackhawk]

Bruce - I setup my own lathe/indexer using a Rikon lathe and an ASM98AA motor. I set it up using a toothed belt with a 3.6 to 1 ratio. I have not had any trouble with this setup. I have done 3D work and have turned up to 6" diameter pieces. I will admit that I have not done a lot of turnings to date, but so far, so good.

http://www.talkshopbot.com/forum/showthread.php?t=11532

[bruce_taylor]

Thanks for the input Brad! I've read about your project and you and Don Clifton are certainly my inspiration for this adventure. I think of a geared set up something like don has setup on his system. What are you using for models and toolpathing. Are you using the shopbot post processor. I am looking at the rikon but would like a little more length on my 60 y axis where I plan to but my setup, so I'm looking at other options. Some older cast iron models with shaft coming out the back to mount a gear to would be optimal I will look for something in the coming days. Certainly looking at all options and appreciate the support I've already received from Don Clifton and Brady Watson and others.

[blackhawk]

Bruce - I use Aspire for my modeling and just output the sbp file using the post processors that come with Aspire.

With the Rikon, you can actually add on as many extension beds as you want. Each extension bed is machined on the end to accept another extension bed.

I went with the belt setup, so that I can switch easily from the indexer to a standard lathe. I can switch over in less than 2 minutes. Running off the AC motor makes sanding so much easier.

If you are really set on gears, the Rikon does have a shaft coming out. The stepped belt pulley is just held onto that shaft with setscrews. The pulley is easily removed to gain access to the shaft.

[bruce_taylor]

Good info Brad! The Rikon is a nice looking setup for sure. How long is the shaft that comes out the end? Could a gear be mounted on the end of the shaft and still have the belt option? I would like to be able to use the lathe too. Is anyone using the shoptbot pp and artcam for models? I will be going up to visit Don Cliftons setup as soon I get a chance. Would like to go to the upcoming camp but I have several conflicting things in my schedule that I'm not sure I can work around. Just not enough hours in the day or days in the week. Thanks again for the input.