# Are most rotary tables like this?



## WobblyHand (Feb 26, 2022)

Just put my new Vertex HV-6 rotary table on the mill.  If it is set to 0 degrees, should I have any expectation that the slots would run true to the mill table?  They are rotated, about 3 degrees off.  I have to rotate the table to 3 and about 18 minutes to indicate within a few thousandths.  Is there a way to "calibrate" the table?  

I know I can move the pointer a few degrees, but it isn't enough.  I did try.  Is there any other means to clock the table?  The base (to stand up the table) is perpendicular to my mill table slots since I indicated it. Just checking if this is an ordinary angle offset, or not.  It's not like they ship a beginners (new) user guide with these tables!


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## woodchucker (Feb 26, 2022)

why would you want that?  if you think about it, you would probably want it off by more than 3 degrees, you want the clamps to be out of the way of 0. But where is good??? who knows.


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## WobblyHand (Feb 26, 2022)

woodchucker said:


> why would you want that?  if you think about it, you would probably want it off by more than 3 degrees, you want the clamps to be out of the way of 0. But where is good??? who knows.


In use, I guess you are right.  

But right now I am trying to machine a fixture plate, and I have to hit the center of the slots.  This is just for the tee-nuts.  The offset is not even a nice number, like on an even number of degrees, which will make it harder (for me) to index.  I can barely remember 0, 90, 180, 270, not 3 degrees, 18 minutes and 37 seconds, or whatever the heck it is.  It also messes up the symmetry of the design   More seriously, I need to redesign since the holes would end in the counterbores.  A 15 degree offset would be grand, 3 and change degrees is not good.  I see more design work ahead.


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## Janderso (Feb 26, 2022)

I know the value of the fixture plate. I’ve made a couple.
The beauty of these sacrificial tables is you drill and tap wherever and whenever you need.
In my experience, I wouldn’t get too caught up with it. It seems like when you want a tapped hole to be….right…there. It isn’t, so I just make one.
$.02 cents worth.


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## WobblyHand (Feb 26, 2022)

Janderso said:


> I know the value of the fixture plate. I’ve made a couple.
> The beauty of these sacrificial tables is you drill and tap wherever and whenever you need.
> In my experience, I wouldn’t get too caught up with it. It seems like when you want a tapped hole to be….right…there. It isn’t, so I just make one.
> $.02 cents worth.


Thanks for the perspective.  I was trying for it to not look like a disaster before I started.  I do realize they do get _improved_ and modified over time.  

Well, have to come up with something manageable.  There's no way I could index that many holes and not mess them up bad, if I don't stay on even numbers.  Had wanted the fixture holes on 0 degrees, but they really don't have to be there.  Or I could rotate the mounting holes slightly.  Ok, something to think about.

Guess, the answer to my question is:  yes, rotary tables do have some arbitrary offset, and it is up to the user to deal with it.  And no, there is no way to clock the table.  Having never had a rotary table, I did not know this.


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## 682bear (Feb 26, 2022)

I have just put a piece of tape on the table and used an ink pen to make a mark at zero... 

That is pretty standard practice on the 30 inch rotary table we use at work.

-Bear


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## cathead (Feb 26, 2022)

Can't you decouple the drive and then rotate the table to where you want it?  On my table there is a handle to loosen 
and then disengage the worm so the table is free to rotate.  After the table is rotated to the desired position, one can 
reengage the worm and tighten the handle.


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## WobblyHand (Feb 26, 2022)

cathead said:


> Can't you decouple the drive and then rotate the table to where you want it?  On my table there is a handle to loosen
> and then disengage the worm so the table is free to rotate.  After the table is rotated to the desired position, one can
> reengage the worm and tighten the handle.


There is something like that on my table.  Think I have to remove the crank handle to access that.  There is a little tee-handle to loosen.  Then, if I understand correctly, there is a collar of some sort which rotates an eccentric to engage or disengage the worm.  (That's how my dividing head works.)  Hey, it's worth a try.


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## Alcap (Feb 26, 2022)

I’m not 100% sure but is this what your talking about , around the 7 minute mark 



.   I have the same one as Joe Pi and fixed mine too


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## cathead (Feb 26, 2022)

Loosen the "tee" handle and rotate the whole crank assembly clockwise to disengage.


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## WobblyHand (Feb 26, 2022)

Alcap said:


> I’m not 100% sure but is this what your talking about , around the 7 minute mark
> 
> 
> 
> .   I have the same one as Joe Pi and fixed mine too


Something like that.  Ok, that is an extended pointer - a nicer version of what @682bear mentioned.  Not skilled enough to make that just yet, but sure would be nice to make.


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## WobblyHand (Feb 26, 2022)

cathead said:


> Loosen the "tee" handle and rotate the whole crank assembly clockwise to disengage.


Will try that tomorrow.


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## RJSakowski (Feb 26, 2022)

My 12" Enco RT lines up perfectly with the index mark when the slots are parallel with the vertical mounting surface. The 6" Tormach 4th axis which appears to be built on a Phase II RT is about 30º off.


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## woodchucker (Feb 26, 2022)

682bear said:


> I have just put a piece of tape on the table and used an ink pen to make a mark at zero...
> 
> That is pretty standard practice on the 30 inch rotary table we use at work.
> 
> -Bear


that's pretty much what I did  see this: https://www.hobby-machinist.com/threads/steady-rest.97516/page-2#post-923124   #19


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## Manual Mac (Feb 27, 2022)

I’m not sure if this is what you are talking about, but on my 6” four slot RT I removed the rivited-on degree pointer (it was off a number of degrees when the slots were 90º (or lined up) to the mill table. and would put a silver verithin line on the RT body when the slots were 90º or lined up with the slots on the mill table.
i finally made A zero pointer plate and drilled & tapped for the (now) adjustable zero pointer.
much easier for me to use.
not sure how this would work on a 3 slot RT, but 1 slot would be able to be zero’d out.
or I may be full of shirt.
As always, YMMV


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## Flyinfool (Feb 27, 2022)

It has always been my opinion that those slots are not precision machined, they are just there for clamping things down. I have never tried to index anything off of the T slots.

But now you did get me thinking of making a sacrificial plate for my RT......
I have had some pretty crazy setups just to get things clamped down. It would be nice to just drill and tap a hole as needed where needed.


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## WobblyHand (Feb 27, 2022)

Manual Mac said:


> I’m not sure if this is what you are talking about, but on my 6” four slot RT I removed the rivited-on degree pointer (it was off a number of degrees when the slots were 90º (or lined up) to the mill table. and would put a silver verithin line on the RT body when the slots were 90º or lined up with the slots on the mill table.
> i finally made A zero pointer plate and drilled & tapped for the (now) adjustable zero pointer.
> much easier for me to use.
> not sure how this would work on a 3 slot RT, but 1 slot would be able to be zero’d out.
> ...


I have a four slot RT.  Seems that the angle offset is not abnormal.  My pointer is fixed with screws, so I could make an offset pointer.  Seems even a Vertex RT is a kit.  Oh well, I'll mod the pointer.  Have some 0.010" brass I could use, if I can cut it without distortion.


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## woodchucker (Feb 27, 2022)

WobblyHand said:


> I have a four slot RT.  Seems that the angle offset is not abnormal.  My pointer is fixed with screws, so I could make an offset pointer.  Seems even a Vertex RT is a kit.  Oh well, I'll mod the pointer.  Have some 0.010" brass I could use, if I can cut it without distortion.


10 thou use a scissor, then re-flatten.
That does not make it a kit.  That makes it different than you think it should be.
Add another pointer like Manual Mike.. A valid thing.


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## WobblyHand (Feb 27, 2022)

woodchucker said:


> That does not make it a kit. That makes it different than you think it should be.


Guess it is a matter of expectation management.  Seems strange to me that stuff sold to do relatively precise stuff may be manufactured with oddball offsets, or require calibration, which require some degree of knowledge and talent to fix.  For this example, it is an easy fix.

Since entering this strange world of machining and precision, I have experienced more of this than I had anticipated.  Perhaps it is all due manufacturing to a price point, but it continually surprises me nonetheless.  Just my perspective.  YMMV.


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## woodchucker (Feb 27, 2022)

WobblyHand said:


> Guess it is a matter of expectation management.  Seems strange to me that stuff sold to do relatively precise stuff may be manufactured with oddball offsets, or require calibration, which require some degree of knowledge and talent to fix.  For this example, it is an easy fix.
> 
> Since entering this strange world of machining and precision, I have experienced more of this than I had anticipated.  Perhaps it is all due manufacturing to a price point, but it continually surprises me nonetheless.  Just my perspective.  YMMV.


well, then we need to see what was going on in the 30s to the 70s here in the USA.. were they all as you think, or did they vary?   I'm not sure.
Maybe we can ask some guys out there with some old equip what it looks like.


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## WobblyHand (Feb 27, 2022)

woodchucker said:


> well, then we need to see what was going on in the 30s to the 70s here in the USA.. were they all as you think, or did they vary?   I'm not sure.
> Maybe we can ask some guys out there with some old equip what it looks like.


Not sure if the old iron was made "well" or not.  Not relevant for my needs.  RJ's table seems to be fine.  Mine isn't.


For me, the scale reads 3 degrees and 11 minutes, if I am getting this right.  The horizontal slots are aligned with the x axis of the mill table.  So shifting the pointer isn't really going to help.  Crudely, it is fine.  I can make a pointer to zero.  But to get things precise, I have to set to x + 11 minutes to get everything to come out right.  It may not matter to you, but I don't like that error.  A 3 degree error is ok, but not convenient.  3 degrees + 11 minutes, no, that's no good, as it will lead to many screw ups in setting.  A multiple of 4 degree error would be fine, as the dial would read correctly.

I am going to watch some rotary table teardown videos to see if I can understand this RT some more.  Maybe it is adjustable, maybe not.  Hope to learn some more about the table.  The exploded part diagram I have is a print of a xerox of a xerox, if you catch my meaning.  The detail is blurred, so I don't quite understand it.  Once I understand it, I can tear it down, if I need to.


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## RJSakowski (Feb 27, 2022)

I took a closer look at my 6" RT and the offset is actually about 20º.  The design of the base fairly well precludes aligning the index mark with one of the four cardinal points.  The RT is a H/V model and placing the index on the surface next to the vertical base would make it virtually impossible to see when used in the vertical position.  The opposing surface and back surface would be inconvenient to see as well.  That leaves the front surface and the 20º offset.

The Tormach RT is a 4th axis RT and I can arbitrarily set the zero degree mark wherever on the DRO readout so not a problem but the Phase II manual version this is built on has the same offset.


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## RJSakowski (Feb 27, 2022)

My Enco RT has an adjustable dial so I can set the the fine adjust to anything within a 4º range.  I use the index marker and degree scale for a rough setting only and make my fine adjust with the dial.  The 90:1 worm gearing ensures that I drop into the same relationship between the dial and the table whenever I disengage and re-engage the worm drive. @WobblyHand, if yours is configured similarly, free rotating to a new position and remembering to add/subtract a 3º offset should get you where you want to go.

When working with the RT for a complex set of rotations, I always make up a table of positions for each operation.  It saves the wear and tear on the old noggin and potential head injuries from banging my head against the wall when I screw up a part.


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## WobblyHand (Feb 27, 2022)

Stefan Gotteswinter to the rescue.  Saw his teardown of his Vertex HV-6.  




Have a much better feeling for how the table works.  I'll try taking out that 11 minute offset.  If successful, I will try to take out the 3 degrees + 11 minutes.   I'll try this right after lunch.  For all I know, this is trivial - or it opens a new can of worms, will find out soon!


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## Manual Mac (Feb 27, 2022)

You guys are blinding me with science.
in the old days when I did this for a living I only used the RT’s (great huge ones) for making wheel centers for & also hubs for axles. And bolting fixtures to RT’s to machine other parts with round nose end mills, etc, etc.
never used seconds, etc.
I’m not an expert.
The silver line on the RT body next to the rivited-on pointer is how I used to zero everything out.
Disregard the set-up, this from couple years ago, only meant to show the verithin pencil mark.
iI always thought my 6” table was a re-badged Vertex, I now think it is a re-badged Vevor.
And the large Yuasa & Troyka etc. RT’s i used for a living were Swiss Watch’s compared to my little 6”one.
But it works fine for me in my little garage machine shop with my little machines, now that I am retired
Cheers


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## woodchucker (Feb 27, 2022)

not sure I understand. I didn't see anything in that video about what you are talking about.


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## WobblyHand (Feb 27, 2022)

woodchucker said:


> not sure I understand. I didn't see anything in that video about what you are talking about.


He didn't even mention offset.  Of course, it may have been trivial for him to deal with.  Stefan does stuff in a matter of fact way and often assumes we all know some (basic?) things.  I just needed to see the same model RT come apart, to better understand how it worked.  

Honestly, I just want to get rid of the 11 minute offset as that will mess me up.  If the level of minutia gets too great (pun actually intended) then I can get overload and forget things.  Personal frailty, I suppose.  Keeping things to degrees is my way of dealing with it.


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## 682bear (Feb 27, 2022)

Does the pointer adjust side to side if you loosen the screws holding it?

If it doesn't move far enough, I would use a Dremel to slot the holes enough to adjust out the 11 degrees...

If might be more simpler to set the rotary table at the 3 degree mark exactly, lock the table, then loosen the mounting bolts and indicate the t-slots by moving the entire unit... like you would a vise.

Unless, of course, the rotary table is 'keyed' to the mill table... I always just remove the keys, anyway.

-Bear


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## WobblyHand (Feb 27, 2022)

682bear said:


> Does the pointer adjust side to side if you loosen the screws holding it?
> 
> If it doesn't move far enough, I would use a Dremel to slot the holes enough to adjust out the 11 degrees...
> 
> ...


Yes it does adjust some, but not enough.  So I could slot out the hole some, or make a new pointer.  Only thing that bothers me is the 11 minute offset.  That is the part I need to take out, at least to make the fixture plate (unaltered).

I agree, but it would make this a pain in the behind to set up.  But this really is a one shot event (I hope).  Might be ok.  

I haven't keyed the table.  Personally, I don't like having the tooling sitting cockeyed on the shelf.  Haven't ever found it a problem to tram dividing heads, vises, or rotary tables.  Only takes a couple of minutes.  Just have one partially tightened bolt as a pivot, and the other one looser. Indicate, tap, repeat a couple times and you are done.  Then tighten carefully.  Pretty quick in practice.


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## WobblyHand (Feb 27, 2022)

Manual Mac said:


> You guys are blinding me with science.
> in the old days when I did this for a living I only used the RT’s (great huge ones) for making wheel centers for & also hubs for axles. And bolting fixtures to RT’s to machine other parts with round nose end mills, etc, etc.
> never used seconds, etc.
> I’m not an expert.
> ...


It _appears_ your 0 on the dial lines up with the seconds 0, when your slots are vertical.  Mine doesn't do that.  _How did you make that happen?_ Loosen the table and turn it?  If I were zeroed like that and the pointer was off, I'd just make an offset pointer, like you did.  (The line.)

Right now I have locked my table in the right position, (both the RT and it's horizontal slots are trammed) but not sure how to get the dial to zero without a lot of trial and error.  I'll mess with it some...


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## Larry$ (Feb 27, 2022)

RJSakowski said:


> When working with the RT for a complex set of rotations, I always make up a table of positions for each operation. It saves the wear and tear on the old noggin and potential head injuries from banging my head against the wall when I screw up a part.


Me Too! I made an 11" auxiliary table with 8 slots, for my 8" Vertex to get more clamping area & clamping locations. Never even considered on clocking it. Not sure that T slots are accurate enough to matter. But then I've never made a fixture plat for it either.


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## Manual Mac (Feb 27, 2022)

Wobbly, you may want to take your RT apart to understand it a little better. Pretty simple & kinda fun . Look for assembly grit inside, mine was pretty clean & oiled well.
Remember, there is a grub like screw (backlash adjustment) that has to be backed out (I didn’t see this at first) before the handle & worm assembly will pull out. Mine did anyway.
i kinda screwed up when I assembled it the first time by trying it to get all the backlash out. I got it too tight & noticed wear on it the next time I took it apart. My fault.
I now leave a bit of backlash, but I always set up turning the handwheel the same direction, so no harm, no foul.
if you have degree pointer screws (mine was riveted on) that are few degrees off, just make a longer pointer plate.
When I re-assemble mine the zero degree pointer always ends up pointing at the same degree mark, I’m not smart enough to figure out why. Probably simple? dunno.
Also the minute dial zero can be set anywhere you want it with the allan grub screws, but I’m sure you already knew that.
I have to oil all the ball oilers often while using mine. My table seems to need a lot of lube to move smooth. 
Once again, I am no expert, but this works for me.
Cheers


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## WobblyHand (Feb 27, 2022)

Manual Mac said:


> Also the minute dial zero can be set anywhere you want it with the allan grub screws, but I’m sure you already knew that.


Ahem, of course I knew that, but ahem, I seemed to have forgotten that ...  duh.  Thanks for reminding me!  That will get some adjustment.

It seems the worm is cut at 4 degrees.  So I can make the error be whatever it is, modulo 4 degrees.  Freewheeling the table by one degree will not re-engage the worm.  So the table could be set to 15 degrees, 11 minutes. (Choices are: -4.816, -0.816, 3.183, 7.183, 11.183, 15.183, etc. )  And maybe I can get some of that 11' out with the dial.  My outer ring of holes is at 15 degree increments, so that would be close enough to work.  

Boy, this has been exercising the grey cells.  Going into this, didn't think making a fixture plate had this many nuances.  There are some, if you want it to come out a certain way.


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## WobblyHand (Feb 27, 2022)

Ok, got the 11 minutes adjusted out by rotating the outer dial.  My goodness, what a mental block that was!  I can adjust the pointer to 2 degrees, more requires opening the slots by 3mm or so.  I can do that.  Thanks for getting me over the hump!  Done.


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## wildcatter (Feb 27, 2022)

I dont have a RT but I saw this addressed somewhere, likely on a utube video. maybe Joe Pi . Might be worth searching his vid, unless you have it solved already.


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## Janderso (Feb 28, 2022)

WobblyHand said:


> Thanks for the perspective.  I was trying for it to not look like a disaster before I started.  I do realize they do get _improved_ and modified over time.
> 
> Well, have to come up with something manageable.  There's no way I could index that many holes and not mess them up bad, if I don't stay on even numbers.  Had wanted the fixture holes on 0 degrees, but they really don't have to be there.  Or I could rotate the mounting holes slightly.  Ok, something to think about.
> 
> Guess, the answer to my question is:  yes, rotary tables do have some arbitrary offset, and it is up to the user to deal with it.  And no, there is no way to clock the table.  Having never had a rotary table, I did not know this.


I should add , my 10” Gorton does not line up either


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## WobblyHand (Feb 28, 2022)

Janderso said:


> I should add , my 10” Gorton does not line up either


Mine does now.  

Rotating the dial, plus offsetting the pointer did the trick.  Until reminded by @Manual Mac, I didn't quite comprehend the dial adjustment.  The hardest part of the job, was realizing what he meant.  Once I figured it out, it was pretty easy to change.  

One can freewheel the table to multiples of 4 degrees from your current position, with no problem.  (Assuming a 90:1 drive)  The worm repeats every 4 degrees.  Fractions of 4 degrees are adjusted by turning the dial.  The last little bit is to offset the pointer.  I had to slot mine to get a little extra travel.  Quite simple, as it all turned out.


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## Larry42 (Feb 28, 2022)

And the winner is  ..... WobblyHand by a degree. Congratulations


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## pontiac428 (Feb 28, 2022)

So, I have a Kamaura 8" RT that I really like.  Mine indexes to zero on the t-nut channels, and can be adjusted by backing out the worm gear preload spring stopper screw and adding shims to the worm shaft.

While I understand the desire to be indexed to zero on the x axis, I don't know that it matters.  Just like it doesn't matter where on the x or y axis of your mill table you decide to plop down a part and go to work.  All that matters is that you have your dimensions referenced to the work piece.  It doesn't matter if you start a x-axis cut at 24.88325 inches, because that is what you reference to zero.  Same on the rotary table, 29deg55'40" to 74deg55'40" looks the same as 45deg to the part.  This is where a pad and pencil helps.  It's kinda brute force compared to CNC or DRO, but mathematically, zero is wherever you say it is.


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## WobblyHand (Feb 28, 2022)

pontiac428 said:


> So, I have a Kamaura 8" RT that I really like.  Mine indexes to zero on the t-nut channels, and can be adjusted by backing out the worm gear preload spring stopper screw and adding shims to the worm shaft.
> 
> While I understand the desire to be indexed to zero on the x axis, I don't know that it matters.  Just like it doesn't matter where on the x or y axis of your mill table you decide to plop down a part and go to work.  All that matters is that you have your dimensions referenced to the work piece.  It doesn't matter if you start a x-axis cut at 24.88325 inches, because that is what you reference to zero.  Same on the rotary table, 29deg55'40" to 74deg55'40" looks the same as 45deg to the part.  This is where a pad and pencil helps.  It's kinda brute force compared to CNC or DRO, but mathematically, zero is wherever you say it is.


Yes, I agree.  But as a new user to indexing on an RT, I really wanted to make it easier on myself to do the very first operations on the table.  Later on it won't matter much.  I do have a bunch of holes to make, and wanted them on easy to remember boundaries.  It's a crutch, but, it's a way to start.  Later, I can set the crutch aside.


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## pontiac428 (Feb 28, 2022)

That's a good reason.  It would be worth it to take the time to make setup repeatable by adding an alignment bar to the bottom and clearancing the mounting bolt slots as needed.   I haven't torn down a vertex type RT, but I bet there's a way to zero your table to the index that doesn't involve moving the pointer.  Moving the worm gear's location forward or aft with shims would be nice and proper.


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## Manual Mac (Feb 28, 2022)

Pontiac, I always square the RT to the table when I use it. Probably don’t need to. But i do.
Also the pointer does not have to be aligned in any special way, zero is where you put it, like you said
It would seem RT degree pointers are random by manufacturer.
I just find it easier (for me) to have the zeros lined up with the table slots (or 1 slot if 3 slot table) when it is flat, or when set upright to have the table slots level with the table. Seems easier to make set-ups. I could be wrong.
And moving the pointer or just drawing a line on the RT body is much easier (for me) than trying trial & error to shim the worm assembly, if that is even possible on these cheap tables.
This is just my opinion, possibly mine alone in the whole universe.
YMMV, Cheers


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## pontiac428 (Feb 28, 2022)

You're not alone in your opinion at all, and I agree that mounting an RT indexed to zero is easier and more desirable.  I just wanted to point out that zero is arbitrary (the origin is defined by the machinist) and doesn't affect one's ability to perform work if it's not dead on the mark to start.  We have to make do often enough in the home shop that I thought it was worth discussing how RT work can be accomplished in the absence of perfect conditions/ideal equipment.


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## Toolmaker51 (Mar 9, 2022)

Push or shove, two things re apparent. Home shops make do; commercials shops stick on some tape.
Me, I like some feature aligned to one or another axis too.
I'd remove the keys, align and clamp ro-tab, clock the center, make the plate per divisions you chose.
Break down set up, replace the keys, then work reconciling the table/ crank/ pointer arrangement.
BTW, I don't leave keys mounted. Just when 'dropping' tooling on and I want quick. 
I can clock a vise >.001 in 1 or 2 laps. Keys have damaged more work tables than me sliding vises around in 50 years.


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