Thread: Which 8 inch Rotary Table to Buy?

Originally Posted by simonl

Thanks Swarfmaker. Now which lever is for the reduction of backlash? Is it the one above the turn wheel?

Simon

Yes it is. It's the skinny lever on the ring behind the graduated dial. The other one on the deck with Tommy bar is the lock. Loosen the lock and then move the eccentric lever. You can actually disengage the worm completely and the table should rotate freely. The backlash adjustment (worm engagement) is an essential feature on a rotary table if you want to continuously mill along a radius with table clamp disengaged. Many of the Chinese jobs don't have this facility and H&F may have an odd below spec item with excessive worm or wheel (or both) runout. It's very easy to check for on a rotary table. Also once you've reduced the backlash, grab the table and twist it back and forth, you'll be able to feel the play between worm and wheel. Don't let them get your card or cash before you test it, they should have a stack of them as floor stock for the sale. They are pretty good on exchanges though.

The special prices at H&F are very tempting my 6" cost me what the 8" is selling for. If you don't have a dividing head and plan to use the RT for this purpose then the centre height (H1 on the vertex diagrams) will be the decider for you. Swings and roundabouts.

Originally Posted by Swarfmaker1

Yes it is. It's the skinny lever on the ring behind the graduated dial. The other one on the deck with Tommy bar is the lock. Loosen the lock and then move the eccentric lever. You can actually disengage the worm completely and the table should rotate freely. The backlash adjustment (worm engagement) is an essential feature on a rotary table if you want to continuously mill along a radius with table clamp disengaged. Many of the Chinese jobs don't have this facility and H&F may have an odd below spec item with excessive worm or wheel (or both) runout. It's very easy to check for on a rotary table. Also once you've reduced the backlash, grab the table and twist it back and forth, you'll be able to feel the play between worm and wheel. Don't let them get your card or cash before you test it, they should have a stack of them as floor stock for the sale. They are pretty good on exchanges though.

The special prices at H&F are very tempting my 6" cost me what the 8" is selling for. If you don't have a dividing head and plan to use the RT for this purpose then the centre height (H1 on the vertex diagrams) will be the decider for you. Swings and roundabouts.

Thanks once again Swarfmaker. They will be sick of me by the time I hand over my card and I leave minus a few hundy in cash! Here's a question for you (and anyone else for that matter) Speaking of horizontal work using a tailstock, I notice that the bolt holes on the tailstock are fore and aft as in they are inline with the spindle axis of the job. Yet the bolt holes on the RT straddle the centreline or axis, ie they have a bolt hole on either side. Can someone please explain how on earth you set up the rotary table and tailstock in line on your table when the RT bolt holes are either side and the TS are inline? I realise that most probably use clamps, but what's the point of the bolt holes? Are they just lip service from the manufacturer?

Simon

I don't have the tailstocks for the tables but the tailstock is similar to the one on my Dividing Head and they are a fiddle. The tables have a 2MT or 3MT socket and you can use a dead centre in that to align with the tailstock using a test bar and DTI or just indicate off the job with tailstock engaged. Short overhangs are not usually a problem and the tailstock can be carefully pushed up into position and we're assuming the job is correctly centred on the rotary table. Using the DTI , I indicate the work to ensure the tailstock isn't pulling it off centre. Incidentally my dividing head has a 2mt dead centre and drive dog for between centres indexing.

The way I do it -
Bolt down the T/S and R/T in approximate positions.
Mount a test bar between the two
Run a clock back and forth until you get no movement when it is on the parallel test bar.
End result - R/T - T/S axis parallel with the table.
(if you want the R/T axis parallel to the table, mount the test bar in the R/T chuck).

Michael

Thanks Michael & Swarfmaker!

Simon

I notice that assert plant and machinery have a range of RT their 8 inch sells for just shy of$ 500 same as H&F when not on sale. Does anyone know much about them? Sorry no pic as im on the phone. Not that id pay that when H&F have their sale but they may match or better? Simon

I'm off to H&F to buy my RT. Thanks everyone for their advice and opinions on the subject.

Simon

Well im the proud owner of a vertex 8 inch RT. The guy was not too impressed when i asked him to remove it from its well packaged box for inspection. He muttered something along the lines we can't resell it if its open. He came around when i told him he wont be selling this if he doesn't open it!All seemed well so puchase was made. Got it home and having a play. The quality is ok i wouldn't call it top notch but it will achieve what i want and more and will outlast me! Its all pretty straight forward but bugger me if i can get graduations down to 10 sec of arc! That's a 6th of the smallest division on the main collar what are about 1mm apart! Still yet to work out how the vernier collar on the outside does this with its 60-0-60 scale....Lots of other stuff to buy there. Very temping! Simon

Hi Simon,
Grads on your purchase.
So he was saying if you thought it was no good he would still try and sell it to someone else?

You know there are 60 seconds in a minute, 60 minutes in a degree.
One turn of the handle wheel is 4 degrees, each degree is broken into 60 graduations.
So that gets you to 1/60 of a degree, 1 minute.
The collar 60-0-60 has six vernier graduations either side of 0.(so you can wind either way)
So that gets you to 1/6 of a minute, 10 second of arch.

Stuart

Originally Posted by simonl

Well im the proud owner of a vertex 8 inch RT. The guy was not too impressed when i asked him to remove it from its well packaged box for inspection. He muttered something along the lines we can't resell it if its open. He came around when i told him he wont be selling this if he doesn't open it!All seemed well so puchase was made. Got it home and having a play. The quality is ok i wouldn't call it top notch but it will achieve what i want and more and will outlast me! Its all pretty straight forward but bugger me if i can get graduations down to 10 sec of arc! That's a 6th of the smallest division on the main collar what are about 1mm apart! Still yet to work out how the vernier collar on the outside does this with its 60-0-60 scale....Lots of other stuff to buy there. Very temping! Simon

Top notch comes with a higher price 1 Moore Precise, Horizontal/Vertical Ultra Precision Rotary Table Machine - Machine Tools - Second hand machinery - Wotol.com

I liked your line about the no sale Simon.

Does the table rotate through a complete circle smoothly ie no binding? My 6" Vertex tightens up a bit less than a whisker while rotating suggesting an eccentric wormwheel. Sadly, I didn't ask for the box to be opened.

BT

Originally Posted by Stustoys

Hi Simon,
Grads on your purchase.
So he was saying if you thought it was no good he would still try and sell it to someone else?

You know there are 60 seconds in a minute, 60 minutes in a degree.
One turn of the handle wheel is 4 degrees, each degree is broken into 60 graduations.
So that gets you to 1/60 of a degree, 1 minute.
The collar 60-0-60 has six vernier graduations either side of 0.(so you can wind either way)
So that gets you to 1/6 of a minute, 10 second of arch.

Stuart

Thanks Stuart, I figured that bit out. It's just that you're talking about movements that are about the thickness of the lines. It's pretty much all academic as i will never* need such angular accuracy.

It's funny cause the instruction manual says to only ever turn the handle clockwise. Don't know why maybe something to do with the angle of the worm to the gear. Surely they mean only if you're putting it under load, ie milling while turning the handle?

I now cleaned it up of the "flight grease" and any left over swarf (some in the T slots) and it's looking even better. My M12 clamping kit fits it nicely. I just spent the good part of 10 minutes trying to centralise my first job on it. Takes a bit more practise than the 4 jaw, tap tap here, tap tap there oops too much!

Simon

*Never, for now anyway!

Simon

Originally Posted by Anorak Bob

Top notch comes with a higher price 1 Moore Precise, Horizontal/Vertical Ultra Precision Rotary Table Machine - Machine Tools - Second hand machinery - Wotol.com

I liked your line about the no sale Simon.

Does the table rotate through a complete circle smoothly ie no binding? My 6" Vertex tightens up a bit less than a whisker while rotating suggesting an eccentric wormwheel. Sadly, I didn't ask for the box to be opened.

BT

Bloody Hell Bob! Ok, OK I'm happy with it at only about 6% of that price. It seems OK. I'm not sure whether to treat it like every other machine tool purchase and totally strip it, clean it and add my own grease/oil?

I must admit, it does not have the romance of your Hercus 80:1 Rotary table! Love it!
Stuart, I have been studying your thread "rotary table questions" where you made a D1-4 adapter plate. Thats a very informative thread and I like what you made. I may give it a go soon!

Simon

Originally Posted by simonl

Bloody Hell Bob! Ok, OK I'm happy with it at only about 6% of that price. It seems OK. I'm not sure whether to treat it like every other machine tool purchase and totally strip it, clean it and add my own grease/oil?

I must admit, it does not have the romance of your Hercus 80:1 Rotary table! Love it!
Stuart, I have been studying your thread "rotary table questions" where you made a D1-4 adapter plate. Thats a very informative thread and I like what you made. I may give it a go soon!

Simon

Ah. The little Hercus. A one hand lift and about half the height of the Vertex. I like it too.

Not long after buying the 13 there was a 10 inch Schaublin rotab on US Ebay. From memory it sold for $760. It weighed only 27 kilos and stood 90mm high. Shipping would have boosted the price to around a large. I still lay awake at night wishing I'd bid on the bastard. Nicer looking than a Vertex.

Ha ha
BT

Originally Posted by simonl

Thanks Stuart, I figured that bit out.

hehe I thought I might have misunderstood.
I've been known to tape a piece of cardboard over that collar so you can only see the 0 line. Faster when "the nearest minute" is "good enough"

I've only seen the insides of my 10"r/t but it has two thrust bearings. I cant remember how the worn is held in the base casting, as you say maybe its more rigid when turned CW?

Talking about the vernier collar. Thats free to rotate with just a little pin that hits on the table to stop it right?(my table has grub screw there)

Does the table come with Tee nuts?

Greg has posted some pics of a r/t that was in the $20k bracket(from memory, which is never a good thing with me) had automatic correction of the worn wheel error........... very very nice.

The D1-4 adaptor has been very handy, infact I think its only been off the table once since it was made.
Some of the typos in that thread, its a wonder anyone could understand me. I'd like to think I've improved but I'm not so sure.

Stuart