Need help with dividing head...

In any event, instead of cutting try measuring !!

Take a piece of square stock and mount it on the rotarty table.
a) rotate table until one side measures(trams?) flat with a dial indicator
b) set RT dials to zero
c) rotate table another 90º
d) run dial indicator along edge and see how much error there is from "just using the dials"
e) repete (d) 3 more times
You now have a gauge of how accurate the RT dials are.
 
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Yep mine is a 90:1, so it should indeed be 22 10/20 for a 4 flat split. Looked in my manual and ITS WRONG!!! I even checked again using 22 turns and 10/20 holes and guess what, all the degree marks lined up perfectly. Leave it to the manufacturer to mess up there own manual. I guess I am at fault aswell for not taking 2 minutes to double check the math.
 
One would have expected the Mfg to have given you the correct information. Makes me wonder if this is a single misprint or are there others in the table as well.

I would reach out to the Mfg and let them know. They may have a revised table they could send to you. If nothing else, they may be able to correct their manual so others who purchase this won't have issues.
 
While I insist that understanding and being able to do the math is necessary, there are dividing head calculator apps available.
 
Here's the table from my Vertex Dividing Head. 90:1

As other have mentioned 22 1/2 turns per quarter (90 degrees)
 

Attachments

  • Grizzly (Vertex Dividing Plates) Manual (dragged).pdf
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In days gone by you wouldn't see that kind of mistake very often. Seems that the import mfgs don't check their documentation thoroughly enough. Even if someone at the factory caught it, the factory probably wouldn't want to spend the money to even print an addendum, not to mention reprinting the whole manual.
Mistakes have also shown up with regard to lathe change gear charts
-Mark
 
Armourer said:
I have a rotary table and have only used it a few times but I can't seem to grasp why dividing heads are used as much. To me it seems easier to us the degree marks on the side of a rotary table instead, no need for counting turns or nothing. Just crank from 0 degrees to 90, 180, 270, 360 to do the four flats. I don't know how more simple that could get, but mind you I am not a guy with 20 years experience either
Click to expand...

Fractional degrees would be the main reason. Lets say you need to make a gear with 44 teeth, each tooth is a turn of 8.182 degrees, if you just round off to 8 you will end up with 45 teeth.

Agree if you can use whole numbers a rotary table or spin indexer is easier.
 
Yea it’s an import, I seen spelling and grammatical issues all the time from imported parts and literature. However, math is a universal language and I guess I figured it was right. Ugh, I wished they would start making machines, parts, and accessories here in the USA. Believe it or not, that rotary table had a horizontal face run out of .0035. So, I disassembled it and chucked it up in my lathe (Delta Rockwell11x36) and re- machined all the mating surfaces except for the surface on the casting itself. Now, the runout is +-.0005 and is decently smooth to operate. It was unusable before, I don’t know why they just don’t sell the stuff in kits and let us finish the machining to begging with. Hell, we have to disassemble it, clean, re-machine and rebuild the stuff anyway. Thanks to everyone for all of the information and resources, they will come in very handy.
 
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