Rotary Table Question

[JMI]

Been looking at small (3"-4") rotary tables for purchase and see that some come with a hole in the center of the table while others have the slots continuous and cross at the center.
What are the advantages/disadvantages between the two?

http://grizzly.com/products/4-Rotary-Table-w-Indexing/H5940
http://grizzly.com/products/4-Rotary-Table-w-Clamps/H5685

Thanks

Jim

 

[Tin Falcon]

JMI
The advantages I see in the H5940 is it has the morse taper hole and the indexing plates.
The Morse taper hole will allow you to set up work on centers similar to turning centers on a lathe.You will need a center that matches your RT/index head for this. Also if you have a jig or fixture set up with a Morse taper you can transfer from the mill to lathe or visa versa and not lose center location. . The morse taper hole gives another way of holding locating work on the R/T.
The index plates will make indexing faster and will reduce errors while maintaining accuracy.
the advantage is see with the H5685 is you save some bucks. Personally I think the handle location is awkward for horizontal use.

Tin

 

[rleete]

The hole is a taper bore. Typically it is sized based on the diameter of the table. So, smaller tables have a MT#1 or 2 taper, and the larger ones have a R8. This is so you can use it vertical, and put a chuck or center in it.

The one you listed is MT #1. Personal preference, based on what you are going to use it for, I guess.

 

[Mainer]

Since one frequently wants to center work on a rotary table, it helps -- a lot -- to have a center hole that one can put a reference plug of some kind into.

One thing to think about: a 4" rotary table is quite small. By the time you allow room for clamps, it becomes vanishingly small. If that's the largest size your milling machine or whatever you are going to use it with can accommodate, so be it, but personally I'd try to get something larger. Mine is 9", and except for being at the limit of what I can lift, it's none too big for workholding.

 

[Mike N]

I have a 6" rotary table Horizontal/Vertical. I mounted a 6 jaw chuck to it & I have never taken it off, with both inside & out side jaws it will hang onto most everthing I make.

 

[mklotz]

Two items that I made for my RT that you might want to consider...

I made a tapered plug that fits the center hole on the table. While being machined (thus ensuring concentricity), this plug was drilled through and tapped 10-32, then the uppper end (i.e., the part uppermost when the plug sits in the hole) was bored and reamed to 0.2505".

When the plug is inserted in the RT center hole its top is below the level of the RT table. I can quickly center things like flywheel blanks by turning a pin to fit the blank centerhole with a 0.25" tenon to pop into the plug hole. Very quickly you'll acquire a whole collection of these plugs to use.

If the RT is clamped to the mill table, it's impossible to reach the back of the tapered plug to remove it, should that be necessary. That's where the threads in the plug come into play. I made a miniature slide hammer that threads into the plug. One quick jerk and out comes the plug.

The other item I made was a sacrificial plate for the top of the table. My RT has a 6" table so I made the plate 8" in diameter. It has 1/4-20 threaded holes on 1" centers on two orthogonal diameters for attaching clamps - no T-nuts to fiddle with. In addition to extending clamping area and simplifying the process of clamping, the plate protects the RT table from errant cutters.

 

[kvom]

Marv has a good idea with the drilled/tapped plate. When I was using a large RT with t-slots I found it quite challenging to adequately clamp small pieces with t-nuts as the t-slots did not extend very close to the center.

One lesson I learned with using a sacrificial plate is to machine both sides falt and parallel. I failed to do so and got a resulting piece with slightly non-parallel sides.

 

[gmac]

Given the comments about 4" vs 6" RT's which would people recommend for use with the typical Sieg X2 Mill (when used in combination with a Taig lathe)? I had planned on a 4" RT but now you have me wondering....

Thanks
Garry

 

[ksouers]

Garry,
For an X2 I'd say the 4 inch. You'll be hard pressed to fit the 6 inch, and I doubt there will be any Y axis movement left.

Kevin

 

[lugnut]

Guys the first thing you need to do with your X2 mills if you haven't already is buy one of Little Machine Shops 14" Z rack bars and install it. it will give you almost 6 additional inches of Z travel. I done this on my old X2 and I think Rick did also and it make a bunch of difference when using a rotary table. I think it's only $24 takes about 10 minutes it install. here is a link to LMS and the rack. http://www.littlemachineshop.com/products/product_view.php?ProductID=1486&category=6
Your going to want to use a 3 or 4 jaw chuck on top of your RT and this will leave you with plenty of room.
Mel

 

[Cedge]

Lugnut
Were I only allowed two mods on the X2, the belt drive would be one and the longer rack would be the other. Both add huge advances in capability. Those two items plus a set of DRO's and a power feed make the little machine so much more fun to use.

Steve

 

[gmac]

Great hints fellows - thanks again - so I can go ahead with Guy Lautard's plans for a 3.75" rotary table - topped with a larger dia plate drilled and tapped instead of T-slots. I may never get to building anything with this machinery.... BUT tooling...!!! ;D

Cheers
Garry

 

[Julian]

I use a 6" table on an XI mill with no problems.


Julian.

 

[T70MkIII]

Slightly off-topic I know, but would you add the LMS air spring to X2 must haves?

Thanks.

 

[mklotz]

In my earlier post in this thread I described a centering plug for the central table hole.

If you decide to set up to make such a beast, take the time while you're set up to make a *table* centering plug. In most applications, using the RT demands aligning the RT axis to the mill spindle axis.

RT central holes vary so you'll have to puzzle out how to do this for your personal tool. My RT has an MT2 hole so I turned an MT2 taper to fit and, in the same turning (to maintain concentricity), turned a 0.5" tenon on it that, when the plug is in place, projects about 1" above the RT table surface. This tenon has a 0.2505" hole bored and reamed into it.

[Aside: If your table has a MT hole, you might be able to use the taper end from a junked MT drill. On most of these the taper is soft and can be machined without annealing.]

The table is rough centered by putting a 0.25" dowel pin into the mill collet and moving the table until the pin will slide into the hole. Often this is accurate enough for what I'm doing but, for better accuracy, a DTI can be used on the outside of the tenon.

Once the table is centered, the plug is removed and the plug described in my previous post inserted in order to center the workpiece on the table.

 

[Phil B]

Looks like the H5685 doen't have backlash adjustment whereas the H5940 does. Something to think about.

Phil

Been looking at small (3"-4") rotary tables for purchase and see that some come with a hole in the center of the table while others have the slots continuous and cross at the center.
What are the advantages/disadvantages between the two?

http://grizzly.com/products/4-Rotary-Table-w-Indexing/H5940
http://grizzly.com/products/4-Rotary-Table-w-Clamps/H5685

Thanks

Jim

 

[JMI]

I made a tapered plug that fits the center hole on the table. While being machined (thus ensuring concentricity), this plug was drilled through and tapped 10-32, then the uppper end (i.e., the part uppermost when the plug sits in the hole) was bored and reamed to 0.2505"...

Thanks to all for the replies.

Marv, I assume your tapered plug was steel?

Thanks

Jim

 

[mklotz]

Marv, I assume your tapered plug was steel?

Actually it's brass - what was available in the scrap bin when I made it. However, any material, even aluminum, would work. The plug is never under load or stress so strength isn't a consideration. Steel would resist dinging better but I keep my alignment tools protected so that's not much of an issue for me.

 

[dwentz]

I have the Harbor Freight version of the H5685, and I would recommend not going with this one. It has a tapered hole, and a 7mm thread at the bottom of it, and no way to add index plates. It has a fair amount of slop in it also. I did not pay much for it, but it is one of those tools that if I had to replace it for some reason, I would buy a different model.

Dale

 

[Steam4ian]

G'day all.

A previous post asked about the size of RT for a X2 mill.

My answer would be based on how the RT bolts to the table.

I bought a cheap 4" table (Shoba RT4-36) and was immediately sorry I did, there was no easy way of bolting it to the table with the axis perpendicular to the spindle; also the quality and finish was not good. The foot was wider than the table with not edge or slot to clamp to.
In the process of purchasing the cheap table I had spoken with Minitech regarding the RT4-90 on which they had a special price but were out of stock. A couple of months after I got the poor RT Minitech rang to see if i wanted an RT4-90 at the old price. In a moment of fiscal bravado I said yes and purchased the dividing plates as well.

I am more than happy with the RT4-90, better quality (feels like a machine tool) and it bolts readily to the table. The height will be marginal if I put a 3 jaw chuck on it but i do have the LMS parts for the gas strut mod.

IMHO the 6" RT would be too big for the X2.

Regards,
Ian