Rotary Table Questions


Well-Known Member
Premium Member
A few years ago, I hobbed a spur gear to repair my old mill/drill. I used a gear cutter hobb and rotary angle indexer with an er30 collet to hold the work. It worked and the gear was a complete success.

However, I had wished I had a rotary table instead. I recently made an adapter plate for a new motor for my Hartford mill. Again, I found myself wishing I had a rotary table.

I took a quick look on Ali, Amazon, BusyBee, Accusize, and KBC. They seem to come in 2" increments from 4 up to 20. All are also expensive. So I made search bots for both Kijiji & eBay and I'll see what comes up. I'm in no rush.

My questions here are looking for advice.

What size do you think is optimum?

What features are desirable?

Is an add-on chuck essential?

Are there any add-on accessories that ARE essential or at least highly useful?


Ultra Member
Premium Member
I have an OE 12” BP for my mill. It can only be mounted flat on the table - some of the newer/other brands can be mounted both horizontally & vertically. I think that would be an advantage.

They are heavy (well, the older ones anyway). My RT is quite low profile and very accurate (It divides the circle into degrees, minutes, and seconds. Used it yesterday to set a 39.45* (39* 27”) angle either side of a ref line to bore two 24.05mm holes. Worked great.

I would get the largest RT you can afford - for your mill size 12”+. Why, because if you have an 8” work piece there are only 2” all around for clamping - that is not a lot of room for strap clamps.

I bolt chucks onto it as required. I don’t have any “dedicated“ ones. Pulled the backing plate off of an 8” lathe chuck in the past because it was the best option. I do have some “spare” chucks that I try to use if I can (4J, 3J & 3J independent).

Fixture plates are nice to have for small stuff - you can make one from a chunk of alu sheet.
@Susquatch : I have a 12” rotary table used on my (same as your) Bridgeport mill. It is huge and can sit vertical or Horizontal- although I need to make a base mount for it so the existing slots line properly.
I purchased indexing plates for it and it came with an 8” bison 3 jaw chuck. The chuck only has the one jaw set which sucks but it would be nice to have a 4 jaw and outside jaws - then you can clamp some big parts. With the 12” table you can really mill some large pieces and secure things down. Given the mass of the table it is very solid when machining.
I have made gears and other items and it works great.
In a perfect world having the 12” table AND a smaller, say 6”to 8” indexing head would be sweet. I missed out on one at auction that included gearing to tie back into the power feed for making helical gears - bummer


Ultra Member
Premium Member
Some more points to ponder
- some but not all RT's will allow a tooling plate to be mounted to RT with through bolts into T-slots, thus buying you more available real estate. But some RT's have a ledge or casting that limits so evaluate some pictures
- ability to be horizontal and vertical isvery important in my mind, otherwise you need a dividing head
- adding chuck to RT usually involves a home brew intermediary adapter plate. I have posted some piics so do a search. But be aware the whole thing starts to stack up like a wedding cake & you may run out of vertical room depending on your mill, tooling, part etc.
- trying to make self centering chucks concentric to the RT MT hole can be somewhat futile depending on accuracy you are after. Adapting a 4J chuck vs a 3J gives you ability to dial it in regardless.
- whatever RT you buy, consider teh plates &tailstock while you're at it. Sometimes its harder to reconstruct the accessories years later
- watch Stefan video where he dissects an Asian RT. Like most things they vary in quality

John Conroy

Premium Member
I have a Vertex CS8 Super spacer which is basically a rotary table with a 8" chuck instead of table. I got it used for a good price but it had a worn out gear and it took a while to find a preplacement. I made a 12" table for it using a 12" brake rotor for a GM truck and a 12" round steel plate that I drilled with a pattern of threaded holes for hold downs. With the chuck mounted it weighs 175 LBS so these things are pretty heavy so best to find a way to load it onto the mill table without lifting. It can be mounted vertical or horizontal and I have the indexing plates for it. Used ones are pretty hard to find but if you are patient you'll find one.

As Peter mentioned they do fill the available vertical space between spindle and table pretty fast especially when you add a drill chuck or boring head. That was the main reason I added a 6" riser block to my mill.


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Premium Member
Thanks @Brent H, @PeterT, @RobinHood, @John Conroy.

OK, the largest I can get. Preferably 12+.

Vertical & Horizontal if possible.

About the dividing heads. I have a few pieces already. See photos below. The easiest one to use is the 5C Collet Head. But the 3 jaw chuck head will do angles off the table and is slick even if it is a bit complicated.

20210914_152049.jpg 20210914_152356.jpg 20210914_152356.jpg 20210914_152228.jpg

Do they change anything?
@Susquatch : the 5C collet indexer is great for fast machining on dimensional stock. Accurate but not super strong.

the Indexing head with the chuck - beauty! Solid, lots of options and just as fast as the collet indexer once you set things up.

your three jaw (can change out to 4 jaw) size would be my next purchase. I don’t think I would get a 5C indexer as that requires more collets and the fast operations I can handle with a hex/square collet chuck

the big rotary table will allow you to do some pretty cool things the other 2 machines cannot.

I made my own tailstock for the 12” - it is somewhere on here. Works great


Ultra Member
Premium Member
Usually people buy the RT size they need & that's the end of it. But as table diameter grows, usually so does thickness. Not always depending on the model but something to check.

What I was saying about some RT's can accommodating larger diameter tooling plates (or the extending part footprint for that matter) is kind of depicted by these pics. Its hard to judge based on catalog pictures where the dial or casting upright may intercept, but anyways this is what I was driving at.