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rotary table and the number of slots

H

Hruul

Lee - metalworking novice
Premium Member
I am looking into getting a rotary table, and noticed that some have three slots at 60 120deg. and some have four slots at 90deg. Is there a good reason to select one over the other or does it really depend on what you are planning to mount to the table that makes one better over the other?

Thanks in advance.

Lee
 
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The number of T-slots is usually proportional to the table size. If you have the choice for a given table size, get more slots for the reasons others gave above. But I wouldn't let fewer T slots stop me from taking advantage of a good buy. You can always make it work.
 
Most 6" rotabs have three slots for reasons such as Susquatch mentions, four slots will be common in 8" and up. I prefer my 8" with the four slots due to the type of work I use it for combined with the specialized fixtures I make to go on it.

51805563578_7a15cb6462_n.jpg
 
1018Machine said:
Most 6" rotabs have three slots for reasons such as Susquatch mentions, four slots will be common in 8" and up. I prefer my 8" with the four slots due to the type of work I use it for combined with the specialized fixtures I make to go on it.

51805563578_7a15cb6462_n.jpg
Click to expand...

Interesting centring fixture!

I too have been pondering the 4 vs. 3 question so it’s a timely topic. I had come to the decision that 4 was better for more flexibility of fixturing things.

D :cool:
 
A very interesting set up @1018Machine. Can we ask what type of work are you doing? Or is it," you can ask, but if I tell you, then--"
For centering, perhaps a 4 slot might be easier to get work centered then a 3 slot.
 
1018Machine said:
Most 6" rotabs have three slots for reasons such as Susquatch mentions, four slots will be common in 8" and up. I prefer my 8" with the four slots due to the type of work I use it for combined with the specialized fixtures I make to go on it.
Click to expand...

Can we get a better look at how you did your quill DRO Scale?

51805563578_7a15cb6462_n.jpg
 
1018Machine said:
I'll snap a pic of it when I head out to the shop. It's a four axis model from DRO PROS, I used Z as the quill and U for the knee.
Click to expand...

OK, looking forward to see how you did the quill. Looks quite different from what I did.

I did the Z & U thing too. Then I added them together for a total Z. I love it!
 
As others have said, it depends. I have a 4 slot, it is a pain in the butt (it came to me as a bundle purchase, set up and works well - once the chuck is centered, but getting it on center is the chore).

Plan before you buy. Like Susq says, you can make anything work. If a chuck is going to be the primary resident on that rotab, then you should identify the chuck and how to mount it when you buy the rotab.

For a rotab, it is nice to have a front mount chuck (makes centering easier, you don’t need an adapter plate, you can use a chuck the same size as the rotab table) - the 3 bolt front mount is very common for 3J & 4J scroll chucks. Obviously there are options (see comments above) - make/buy a mounting plate, drill more holes in the chuck body, source a front mount chuck with 4 mounting holes, etc.

If you are purchasing new, then you have choice. Let us know how you make out.
 
Susquatch said:
OK, looking forward to see how you did the quill. Looks quite different from what I did.

I did the Z & U thing too. Then I added them together for a total Z. I love it!
Click to expand...
As promised, here's my mounting idea! Nothing fancy just some 1018 plain carbon steel machined to fit the application.

Sorry for the hijack @Hruul.....
 

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Susquatch said:
Go figure!

That said, 6in is still tiny.
Click to expand...
Not on a Mini-Mill: the Sherline 4” plus 5” plate is perfect. I have a somewhat lengthy post for my “Happening” thread showing the various accessories for my Sherline (my shoulder threw a wrench in completing it), but I should have it posted soon-ish.
 
1018Machine said:
As promised, here's my mounting idea! Nothing fancy just some 1018 plain carbon steel machined to fit the application.
Click to expand...

In your first photo, it wasn't obvious how you did it, but the photos you just provided show it is very similar to mine.

20220908_105235.jpg
20220908_105235.jpg

You can see my whole install here:

Susquatch

Post in thread 'Installing a DRO on a Hartford Bridgeport Clone.'

@PeterT & @StevSmar - this photo might help explain my answers to your questions and advice.

There are already two small machined pads on the quill indicator. The two flats and the two ledges on both pads seem to be quite well aligned to the spindle. See item 1 and 2 in the photo below. I used an indicator mounted on the table and then used the knee to check each of them in two planes (x&y). Checking X & Y at two different knee heights implies Z is ok too.

20210609_180311~2.jpg


I took the liberty of adding a 3rd arrow above to show where the read head will mount. If you are familiar...
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1018Machine said:
Sorry for the hijack @Hruul.....
Click to expand...

As you spend more time here, you will come to know that hijacked threads are a part of the culture on this forum.

No apologies needed.
 
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