Indexer questions

[coryatjohn]

Ok, I've had my shopbot a couple of years and have turned a lot of wood, plastic and aluminum into dust and chips. I've also broken enough bits to learn a lot of lessons (and not broken them too!). Now that I have the X,Y and Z axis under control, I finally am getting around to working with my indexer.

I have the large indexer (12") and a 12" Z axis but when I rotate the indexer, the values aren't correct for degrees and moving it 360 degrees doesn't equal one rotation.

What are the "B" values required for the 12" indexer so 360 degrees equals one rotation?

Also, this may sound stupid but I can't find it anywhere, what is the "A" axis for?

I'm running the older 3.6.38 version of the software. Works, don't want to break the machine by upgrading.

Thanks.

p.s. Been a long time since posting here. Haven't needed much help in the last couple of years. Love the machine. It also makes a great planer.

[Kromet International]

I have not had much experience with the shop bot, but I do have many years around CNC equipment the A axis is usually for a 4th axis. Having some kind of a rotary table as an example. I hope this helps.

[bob_dodd]

John check settings under VD number of axis enter 5 , unit type B axis enter rotary deg ,
check settings under VU unit value B ,, MARK CHUCK AND CHANGE UNIT VALUE Increase number till 360 deg , if you get more than 360 , make number smaller , It depends on gear reduction if any , the setting hope this helps

[Brady Watson]

John,
Nice to see you back again. See page 20 (http://www.shopbottools.com/ShopBotDocs/files/SBG%2000171%20Settings%20Unit%20Values%202014%2012 %2017.pdf) for your UV question.

Yes, the rotary axis on a ShopBot is most certainly referred to as the 'B axis'. The 'A axis' is most commonly used on an Accessory tool such as a 2nd spindle. It is also used for one of the indexed rotary axes on a SB 5-axis machine, which can also be considered rotary, as it is addressed in degrees.

-B

[coryatjohn]

Brady - Thanks!

Thanks!

I've made some cool stuff with my machine. My wife keeps me busy!

[coryatjohn]

I tried the two values in the book, one was 65 and change, the other, 45 and change. Neither were correct. The number seems to be somewhere around 54 to 55.

The gearbox didn't have a ratio and had this one it:

NEUGART PLN 70
F-Nr 2119487
OP 02,07 14,
i=12
-001
01/13/2013
Made in Germany

I would sure hate to try and guess that number through trial and error as Bob suggested. No matter what I did, I wouldn't get the exact number and I'm pretty sure that would lead to errors when using it.

Any other ideas?

I sent ShopBot a support request. Maybe they know.

[coryatjohn]

Ok, maybe I answered my own question.

If the gear box is a 12-1, then 54.1667 should do the trick. It seems right. It's hard to tell if it's exact but just from a cursory examination, seems to be dead on.

Maybe that's what i-12 means.

[coryatjohn]

As I continue this conversation with myself, I got a reply from ShopBot and 12-1 is indeed the gear ratio the value is 54.1667 as I had calculated.

Thanks Brady for the primer. As usual, excellent answer and faster than ShopBot.

If you're planning on coming through Tennessee any time in the future, I'd like to hire you to look over my machine, replace what ever needs replacing after three years of light use and adjust it to be super accurate. It's already quite excellent but the only one who's ever touched it adjustment wise is me.

I'd also like the software and firmware upgraded but I'm too chicken to do it myself. Don't fix it if it ain't broke!

[Brady Watson]

As I continue this conversation with myself, I got a reply from ShopBot and 12-1 is indeed the gear ratio the value is 54.1667 as I had calculated.

Thanks Brady for the primer. As usual, excellent answer and faster than ShopBot.

If you're planning on coming through Tennessee any time in the future, I'd like to hire you to look over my machine, replace what ever needs replacing after three years of light use and adjust it to be super accurate. It's already quite excellent but the only one who's ever touched it adjustment wise is me.

I'd also like the software and firmware upgraded but I'm too chicken to do it myself. Don't fix it if it ain't broke!

Hey John - No sweat. Thanks for the invite. I'll look you up next time I am in that neck of the woods. :)

-B

[coryatjohn]

Brady,

If you still have my contact info, it hasn't changed. Thanks!

[coryatjohn]

I got my indexer mounted on the far end of the table. With the indexer in this position, I can mount a 16.5" diameter blank using a 4" end mill. The table is made from 8020 extrusions and is bolted to the SB using 4.5"x1.5" extrusions. The legs are there to support the weight but aren't needed for stability.

First chucked up log:23261

[JimmyD]

Very nice! Any ideas for dust collection?

[Brady Watson]

Sweet :) Whatcha gonna make?

-B

[coryatjohn]

I think the floor will collect most of it. I'll run the DC anyway to get what it can.

What am I going to make? Don't know yet. My wife has all kinds of ideas, as usual. Most likely, I'll just continue making stuff for her. I really like having the capability to do it. That's the big thing.

[scottp55]

VERY Nice John!! :)
Got a guy coming down next Thursday to show him the basics of the Desktop.
He's making Scottish Bagpipes (Scottish Smallpipes) and plans on using the Desktop with the Indexer exclusively with Exotics. Sweet Craftsmanship by Lathe now. Wish I could help him out with indexer, but know nothing about them:(
Should be interesting to see his work:)http://www.pinchbeckpipes.com/
OH, He's looking for someone to help him get it set up and running in his Camden,Maine shop. Hands on learner and offered payment to me to travel, BUT I wouldn't be much help with indexer. I E-mailed the few people I know close by, but either laid up or no indexer experience. If interested maybe contact? I'll know more next week. (sorry John, but didn't want to start a separate thread for him, so just tossed it in here)
Have fun!!
scott

[coryatjohn]

Another indexer question...

I used the Aspire gadget to create a wrapping, rounding toolpath to turn my test log into a blank.

I selected a .5" end mill with .25" depth and 2.6" feed rate, 14k RPM's.

I used the Aspire Shopbot (Indexer)(inch) post processor to save the resulting tool path.

There were all kinds of crazy things in the file. It first tries to dive to -2.5" which would have broken the bit. I removed that.

The bit starts at Z=.45" I set it to material top of 0. That means it's floating in the air. I revised that and moved the Z down .5" so at least it would start in the material.

Then the next weird thing is it's only going .05" per pass. It also asks to set the RPM at 13K. Where did it get that?

Is there something I'm missing?

Am I doing this right at all? Naturally I have my doubts as this is the first indexer cut I've made.

Thanks.

[Brady Watson]

Not sure what is going on, but a few helpful tips.

First, the Zzero should be set to the center of the blank, not the top. While you can do it from the top down, it can get to be problematic, especially when you are doing more than one toolpath with a tool change. How are you going to reference Z0 accurately if you cut that surface away?

Find out the distance from the top of the tailstock to the center. You can do this with a sharp v-bit, the live or dead center and put the bit in line with it in Z. Then move the Z way up to clear the stock, use keypad mode and move the z down until it touches the top of the TS. I would put a piece of masking tape on top to electrically isolate it first.

You can make yourself a Custom Cut for the new Zzero routine. Read up on creating your own Custom Cut file. Copy & paste the Zzero.sbp and instead of it setting the Z height to the thickness of the plate, do a little calculation and account for the distance from the TS top to center. Be SURE to change the default JZ,0.5 (or 1 I forget) to something above the delta of center to top of TS...or it will want to go low after the routine...which is not something you want! As long as you keep that tape on top, you can use it from there on out for accurate Zzeroing for indexing.

If you have one of the newer controllers (I think v209 or newer) you can use the newer MI command which will allow the indexer to spin independently from the rest of the axes. Then you can program a very simple SBP to raster back and forth to dimension your part. Keep the speeds under 300 RPM or it will choke...and keep the feed rates down. Experiment.

Keep a few things in mind with the indexer - it is designed to hold position and the stepper's power curve isn't ideally suited to being used as a lathe. It just doesn't have the power for that sort of thing. It can be used in this way sparingly, but again - it doesn't have the power of a real lathe.

When reducing the size of a blank - or any 'turning' operation, taking off .125" per pass seems conservative, but in reality it is taking off .25" from the diameter. This is even more critical when the part is only being held between centers, as the part has a tendency to vibrate (especially in the center) when cutting under load.

When cutting a rotary part, give yourself an inch or so at each end to make sure you don't hit the chuck or live center. This isn't hard to do...Just make a rectangle as your machining boundary (assuming you are doing 3D) or just as a visual reference for your self to stay out of the 'danger' zones.

After you get running, and you cut your first 'fancy' part, go back to your design and compare it to the cut part to make sure that it is in fact cutting in the right direction. If things are running backwards you won't have any idea on a symmetrical part, but you will certainly see it on a non-symmetrical one, leading to head scratching...

When going around the blank, for operations using it like a lathe, watch your feedrates. It's not hard to cut too aggressively, due to forgetting about Pi and circumferential distance.

Hope that helps.

-B

[coryatjohn]

Brady,

Great stuff. I'll give it a try tomorrow.

Is the post processor the right one? It was built into Aspire. It had no speed control. I can edit the file and do it myself if that's the issue. If it's not the right post processor, where do I get the right one?

I appreciate the help. Usually, once I get past the basic head scratching stage, I am a very good self learner.

The thing was actually cutting the way it is supposed to do after all the fudging factors I put in except it was taking off way too little meat and creating a lot of fine dust instead of chips. I'm sure one of the things you mentioned will fix that.

I should probably skip the gadget thing altogether and use a regular tool path.

[Brady Watson]

I'm not sure which post you have...and I would be the wrong person to ask because I modify mine for different machines freely. The cardinal rule of post editing is to make sure you document what you did in the header of the file. Then copy the commands out of the regular post and paste them in the right spot on the indexer one.

I think I used the rounding routine like once. I like the one in Aspire because it rasters off the corners, but there is one under the Indexer item in SB3 under the Tools menu. It is UBER slow! I just spec out the material in Aspire or DP as round and let it power through the corners - making sure my roughing bit is beefy and long enough to do it. It saves a lot of time...it is roughing after all.

I wouldn't rule out the gadget...play around and try all the strategies. You never know when you'll need one over another.

-B

[coryatjohn]

Ok, I followed your instructions and zeroed to the top of the tailstock. That was an easy fix. I rebuilt the file using the gadget. It created a jog Z to 0 at the start of the file. That was weird. I edited that out and everything ran fine until the last line in the file which was another jog to Z0! I didn't catch that one and it ran my 0.5" end mill right through one of the jaws. Ouch! That's a $44.95 lesson there (for the jaws). The end mill was fine. No damage except to one of the jaws and of course my pride. The result of the cut was pretty good. Essentially, a round blank as expected.

I can see the best way to do things is the good old fashioned way: Lay it out in Aspire and don't use the gadget.

Thanks a lot for your valuable help. I think I know enough to go on. It makes a lot more sense now.

[myxpykalix]

John
Here is one simple jig i made for finding center (Zero) for my indexer.
I took a 2x6 and set it up against my tailstock, marked the center then cut it to that height.
Now when i want to zero to the center on the indexer i just pull out the jig put it on the aluminum track do a C2 and i'm done.

And always remember like Brady says about depth of cut, if you want to cut down .25 you need to cut that depth in half because you are cutting off the top and the bottom (I know that's confusing).

[coryatjohn]

Jack,

Great idea. What do you use for a post processor?

[coryatjohn]

I contacted ShopBot support and Jimmy sent me an up to date post processor file that produces a file that has speed control. I think I'm set now.

[Joe Porter]

John, have you looked on the Vectric Forum? They have a lot of information there about wrapped projects and some very nice tutorials done by some of the members....joe

[coryatjohn]

Joe,

Thanks! I'll take a look.

[myxpykalix]

john
Here is a tutorial that RC Newcomb put together that is a good help when you forget something (like me) on occassions
http://humblesticks.com/cnc-rotary-tutorial.html

[coryatjohn]

Ok, I've managed to create a nice tapered spindle with some details but one thing is still bugging me. In the toolpath file, everytime the system does a jog of the B axis, the darn thing spins around four times and a bit or so for 360 degrees. Any idea why that is? Right now, I'm doing symmetrical cuttings so it won't matter but if I needed to keep things synched up, that would be a mess. I could edit all jogs to moves but I'd like a permanent solution.

Why would a jog in degrees be any different than a move?

Thanks. So far, great luck!

As far as DC, I used some heavy cardboard around the indexer and that worked fabulously to keep chips and dust under control.

[coryatjohn]

Here's my first test object on the finish pass with a ball nose. I modeled it in Aspire.
http://www.talkshopbot.com/forum/picture.php?albumid=83&pictureid=678

[MogulTx]

Congrats John. Looks wonderful!!!

Monty

[coryatjohn]

Thanks! Next I'm going to try to do an STL file.

[myxpykalix]

Now you just need 3 more.....:D

[coryatjohn]

Finished my first 3D indexer job.

Here are the steps it took:

Scan porcelain figure with NextEngine 3D scanner.
Open in Rhino, scale, rotate and add base and mount for indexer.
Save as an OBJ file from Rhino.
Create Indexer job in Aspire.
Import OBJ into Aspire.
Align properly in Aspire.
Create toolpaths:
Roughing rastered along Y axis with 1/2" end mill (20 minute run time)
Finish rastered along Z axis with 1/2" end mill (10 minute run time)
Finish rastered along Y axis with 1/2" ball mill (15 minute run time)
Finish rastered along Y axis with 1/4" ball mill (nearly 3 hour run time)

Then trimmed with bandsaw, cleaned up with hand chisels, sanded by hand and finished with clearcoat.

http://www.talkshopbot.com/forum/picture.php?albumid=83&pictureid=681

http://www.talkshopbot.com/forum/picture.php?albumid=83&pictureid=680

Size is about 5" diameter, 7" tall. Original was about 1" in dimensions. Material is cherry, from my firewood pile.

[Brady Watson]

Cool! Looks like you are coming along just fine.

The good part is that you can burn your mistakes! :D

-B

[steve_g]

Can you make tooth picks?
It really looks neat!
SG

[coryatjohn]

I certainly can burn the chips! My wife is a cat lover and we have cat figurines all over the place. She likes the one I made so it's not going into the fireplace just yet.

As for toothpicks, I can make big ones. Up to 90" long and 6" in diameter (x axis) or 16 inches in diameter and 47" long (y axis)...

[myxpykalix]

Yes John, that's cool but who here has a big enough mouth for a toothpick that size? Excellent work on the cat. It feels good when a project turns out good like that:D

[coryatjohn]

I could probably make a technically correct toothpick out of aluminum...

My wife liked the cat so much she let me buy another cool toy! A spindle sander. I got a nice big one from Grizzly.

[Joe Porter]

It's good when a guy's wife is in on the projects. I am in the process of building a rocking chair that my wife likes and I was able to persuade her that I needed a new bandsaw...joe

[rcnewcomb]

I live seeing people do creative indexer work.
:)

[coryatjohn]

My next project is to try and duplicate the chippendale style legs of our piano. I'm going to do it in Rhino and not scan it.

[myxpykalix]

Hey Randall! Hey another stranger is back!:D Got anything new to show us?:confused:

[rcnewcomb]

Sadly, I've been without an indexer since moving to California back in 2010. I'm trying to figure out if I have room in the garage for a desktop with an indexer. I've been able to buy or borrow time on CNC machines in the mean time. I made a few items this weekend but foolishly forgot to take photos before I gave them away.