Review - Rotary Table

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Central Machinery 3 inch rotary table (Model 98077)

What's in the box: rotary table and two hold-down clamps.

Just purchased the Harbor Freight the Central Machinery 3 inch rotary table (Model 98077) shown at the left. I picked this up at my local Harbor Freight, but it's not listed online any more - it's been discontinued. However, the Grizzly H6195 3" Rotary Table w/ Clamps appears to be the same item; in addition, this often shows up for sale on ebay and elsewhere.

In the past I have purchased machine tools and used them for a while, only to find that they did not work as well as expected. Of course it could have been my technique, but I have also closely inspected some of these tools and found that things that should be square weren't, tolerances were off, parts were loos, etc. So now I make it a practice when I get new tooling to inspect it closely, take it apart if I think it's worthwhile, check tolerances, and just generally get a better understanding of how it's put together.

So here is my evaluation of this rotary table. First, the short version:

This rotary table seems well made for the price. The parts fit well, and are properly finished, square, and parallel where they need to be. The clamps on the other hand are very basic, and seem of limited utility.

Here is a longer version (or you can just jump to the slide-show below):

Bottom of the rotary table - good finish.

Bottom and finished side opposite the hand wheel. Note slots (bottom and side) for bolting to a table. All finished sides are square.

Two sides are finished and parallel. This is the side nearest the hand wheel.

Checking for flatness and parallel. Checks out to less than one thousandth.

Checking top for flatness. Checks out to < one thousandth.

Worm gear removed. Note hole for set screw for backlash adjustment (just to left of mounting slot).

Showing adjustment for worm screw backlash (bottom hex wrench).

Here are the specification for the rotary table, taken from the manual.

The bottom of the table is well finished. In the center you can see the M6x10 flat head screw holding the rotating table to the base.

I note that the hole for the M6x10 screw goes all the way through, but for some reason the threads stop just short of the top. I don't know if this is by design, or just a manufacturing flaw; I plan to "finish" the thread so I can use it for mounting circular plates.

Also note the two mounting slots on the base.

Here's a view of the bottom and rear side. Both surfaces are well finished and square.

Note the two mounting slots on the rear side.

Here's the front side. Also well finished and square.

The front and back sides checked out parallel to better than a thou.

(Here, I'm using a glass plate as a surface plate.)

The table surface also checked out flat and parallel to better than a thou.

Here's the worm screw removed from the base.

Note the hole for the backlash adjustment set screw (located to the left off the mounting slot).

To adjust the backlash, loosen the two screws holding the hand-wheel in place, and tighten the adjustment set screw (shown here using red handled hex wrench); this forces the worm screw against the worm gear.

Backlash is about 30 minutes (one division on the hand-wheel scale).

Here is a close-up of one of the two clamps provided. These fit in the t-slots on the rotary table. As can be seen, these are just stamped out metal pieces, screws, and T-nuts.

Other thoughts:

All of the set screws in the table appear to be metric (just an observation, not a problem). After removing the worm screw and the bottom screw, I attempted to remove the table from the base, but was not able to pull it loose - I didn't really need to remove it, and I didn't want to force it, so I left it at that. I did note however that the the table turned smoothly, but with some force required. Even with the worm gear and bottom screw removed, there was no wobble or play in the table.

For some additional pictures, see the slide-show below.

Nobody seems to have the manual for this, so I scanned it in: The manual for the Harbor Freight / Central Machinery Rotary Table -3 inch Model 98077 (same as Grizzly H6195).

For more opinions, Home Shop Machinist has a discussion on this item here.

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