howard turner rotary table made in china

I am starting out with my recently acquired mill, and the (ever longer) list of projects contain several that would be easier (possible!) with a small rotary table.

The Mill (an SX1LP) seems to suit a 4" table. Reading the forum about such devices I think a simple H/V one would be fine. There seem to be two main choices (in my price bracket) 36:1 (10°/turn) ratio and 90:1 (4°/turn) ratio. The former are a bit cheaper, but the handwheel is on top in the vertical position while the 90:1 seem to have the handwheel horizontal in both orientations which would seem more useable on my small mill.

A 36:1 table turns more quickly than 90:1, making it faster to use, but less accurate. Reduced accuracy doesn"t matter provided only simple angles will be needed. Stuff like hexagon heads.

However, new rotary table owners are soon likely to find jobs where extra accuracy is valuable! Gear cutting is the obvious example, but there are many others, such as cams, helices, drilling awkwardly spaced PCDs etc.

If gear cutting & chums are ever on the menu, a 90:1 table is better. But, oh dear, more money - gear cutting requires a set of division plates or a stepper motor with driver. Manually moving a table to cut 57 teeth ( 6.316° ) per step, soon reduces operators to a nervous wreck and mechanical help keeping track is pretty much essential. I"m not sure 4" tables can be had with division plates, and would recommend a 5" 90:1 table with plates if any advanced functions are on the cards.

Strong rotary tables cost big money. I suggest the hobby type and some expensive makes are unsuited to heavy work whatever the ratio. Brutally hacking out the inner arcs and spokes of several big traction engine wheels at top speed will trash them. Treated with mild respect for ordinary work either ratio should be fine.

I"m actually quite liking using 72:1 and tend to pick that up in preference to my 90:1 table but not sure if there are any to fit your budget with that number of turns as the ARC ones are a bit more costly than the norm.

If (and I repeat, if) you go down the route of adding dividing plates to it, you will almost surely have to calculate all the plate and hole numbers for the 36:1 ratio table.

As far as I can tell, you"re on your own if you want to have a division plate set-up. I was part way through designing such a thing for mine when the need for a 63 tooth changewheel became urgent, so I went for the cheap and cheerful approach of printing a strip of paper with the appropriate divisions marked on it, and taping it round the circumference of the table. Eyeballing alignment with the index mark on the table worked fine - it may not be super precision, but my Imperial threads screw into existing fittings without a problem (and the 63-tooth method isn"t perfect anyway).

The only slight irritation with this method is that the strip is 319.9 mm long for my table, so you have to print it at 33 degrees to fit it on a sheet of A4 - it would have been nice to have printed a whole lot of them on one sheet for different tooth numbers.

The 36:1 model would probably have bigger, stronger teeth and more suited for machining while rotating the table while the 90:1 model will be more accurate but will have smaller, weaker teeth. No problem if locked in stationary position but not as good while rotating.

A more important question may be the number of slots. I think 4 slots is much more useful than 3, which many of the cheaper tables have, as it is easier to fit a 4 jaw chuck which will allow more accurate centering and take up less vertical space than a 3 jaw. Also generally allows easier clamping.

Peter, I have the SX2P mill and apart from it having 25mm more height between table and spindle the table size and X and Y travel are the same as your SX1LP. I started out with a 4 inch rotary table (a cheapie dont go there) but I found it a bit too small. A 6 inch would be too big but came across a 5 inch which is what I went for, came as a set with chuck, tailstock and plates.

A picture below showing its size against the table which gives you some idea. With the 4 jaw chuck and backplate fitted and a Jacobs in the spindle there is only 45mm between the two chucks so I have had to resort to shortening one or two drills in the past. There is more space of course with collet mounted drills and cutters and without the 4 jaw there is 205mm between the rotary face and spindle.

Thanks for all the advice - very helpful. The main projects I have on the (ever growing) list that need some sort of controlled rotation are a motor mount for the Taig lathe so that I can fit a DC speed controlled motor, and some calibrated dials (HH"s Lining tool is on the timeline for that and the ratchet wheels will need the table). The motor mount needs curved adjustment slots but it will be in aluminium so less of a risk.

Thanks Paul for the warning. The reason I asked about relative strength was that the cheap 36:1 tables all seem to have the handle angles towards the centre while the 90:1 ones it is straight. That suggested the cheap tables had a smaller wormwheel, and I was wondering.

Just an update for anyone interested - against advice I ordered table & index plates from a remote supplier (China!) but who shipped from the Czech Republic so no customs or duty (until 1st Jan). Table arrived by courier in less than a week. First impressions good. certainly looks more than adequate for my needs and mill.

On investigation it turned out to be a 110mm diameter 4 slot 72:1 table rather than the 90:1 I thought I was getting. So opened discussions with supplier. Very responsive - offered a swap, or a discount if I kept it. Based on Jason B"s comments about usability I decided on the latter.

The gear teeth are machined into a cylindrical inner part which is bolted to the rotary table. (appears to only be mild steel material and not hardened)

My table is similar to the Grizzley g1049 in the parts list which you called up but does not have ball bearings. Everything else appear to be the same so gear may be interchangeable.

Paul, I couldn"t see any damage to the gear in your photo. I take it you are aware the worm is carried in an eccentric sleeve so that the mesh between the worm and gear is adjustable. If the gear has slipped against the worm and damaged the tops of the teeth, there should still be enough material left to clean up without replacing the gear.

psi Quality Valve 33 choke manifold with for H2S service, 10 x 3”, 10,000 psi manual gate valves, 3 x 4” 10,000 psi gate valves, (1) Swaco hydraulic adjustable choke, (1) adjustable choke

NATIONAL 370M DRAWWORKS AND ROTARY TABLE(Ref#6134Tb)  TSM 500 right angle gearbox, National 17-1/2” table, hydraulic catheads, electric/hydraulic pump, (2) Pullmast PL8 hydraulic winches, Leroi 550 air compressor, 80 gallon air tank c/w dessicant dryer, Detroit Series 60 diesel egine (665 hp), Allison 6061 transmission  Price:  $95,000 USD

17-1/2” OILWELL ROTARY TABLE(Ref#4032N)  completely refurbished, not been used since, new main shaft and bearing, excellent condition  Price:  $24,500

RT375 ROTARY TABLE (NATIONAL)(Ref#15576)  37-1/2” opening, Table axle center inner row sprocket teeth:  53-1/4”, Max. static load rating:  5850 KN, Max. working torque:  33000 KN.M (24,354 ft/lbs),Max. rotating speed:  300 rpm, Gear ratio:  3.56, Overall dimensions:  2468 x 1810 x 718 mm, Weight:  7548 kg, Master bushing (hinged pin drive type) for 37-1/2” National rotary table, Immediately available for shipment from China   Price:  $85,000