Rotary table backlash

[timeone]

Ive just bought a soba 8inch rotary table and was concerned about the amout of backlash in the dial. it seems that if you turn the handle continuus its not a problem but going backwards  there is about 30mm movement before its taken the slack up.

is this normal for rotary tables
should i retun it 

[PekkaNF]

Did it came with instructions?

I don't have this brand, but most of them are very generic.

Normally there is an adjustment to shift worm screw into and out of mesh to worm gear. This will adjust the backlash as well. Mine is locked with t-shape little handle and when you turn vernier that turns an exccentric that moves the worm screw. Often this t-handle or near it has a symbols of mesh and out of the mesh next to it.

While adjusting make a full revolution, you can't get the slack completely out, but it should come fairly small.

When in use: Always turn to one direction and lock the table for a cut if you are indexing. If you don't lock it work it out that way that turn the work against the cutter....

Pekka

[allanchrister]

I have a similar problem with my smaller 4" rotary table which I use on my mini-mill.  Although the instructions do giv an idea how to remove backlash, the photographs in the instruction manual unfortunately show a table with a different 'set' of adjusting screws.  The manual has one screw to adjust the worm, mine has 2.

Although this is not really an issue when using, as I remove backlash and only turn in one direction, I would like the backlash to be minimised as well.  Does anyone else have the smaller rotab with the 2 allen key adjusting screws?

Allan

[timeone]

Reading through google it seems it quite a common thing on rotary tables but how much is acceptable.
I dont have any instructions with the table but im sure i could get some from the seller it would be great if some of the backlash could be removed as id feel more comfortable using it.
The seller has already agreed to refund but i knind of like the table and its pretty good value
and id struggle to fins another for the price

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=300567583513&ssPageName=ADME:B:EOIBSA:GB:1123

[timeone]

A small video clip showing the movement as you can see i move the dial 30 points this is the slack
http://s103.photobucket.com/albums/m141/beekuk/lathe/?action=view&current=backlash.mp4

[dickda1]

I have owned 4 different ones over the years from 4 inch to 10 inch and they they all had some backlash.

The earlier ones came from Germany and Poland with readable instructions.  My latest came written in Chinglish (but nicely machined device by the way).  All required moving the worm into the gear to reduce backlash.

As Pekka notes one moves forward in the same direction a bit (backing up if needed) to wring out the backlash - about the same thing you would do on the cross slide or compound feed on a lathe (unless you have ball screws).

-Dick

[srm_92000]

Hi,

Did you try adjusting the mesh. -
Loosen the black 'T' locking screw - then turn the silver lever as far as it will go clockwise, about quarter turn, the handle should be free and not turn the table at this point. Ensure the table clamps are free and whilst turning the handle re-engage the worm by turning the silver lever back as far as it will go, about a quarter turn again. Lock the black 'T' screw.

If this doesn't help the position of the silver lever can be adjusted.
Mine has two grub screws to the right side of the handle in the main casting - one on top of the other in the same hole!.
Remove the top screw then you may need to use a magnet to extract a ball between the two. To get a closer mesh turn the inner screw anticlockwise a little and repeat the above procedure.
Replace the ball and lock screw.

Axial play of the worm screw can also be a problem this (on my RT) is adjusted by a nut locked with a grub screw behind the handle.
My backlash is 2 (points).
Yours, whilst it seems a lot it is only 30 arc minutes - that's .035" right at the edge of an 8" table, if you always turn the same way and lock the table before machining it may not be a problem, but I think you could get it a lot better with a bit of adjustment.

Of course yours may be different but I hope this helps

Steve.

[timeone]

Steve thanks for that it worked ive got it down to 6 of the marks on the dail so not to bad i expect i could fiddle and get it less bt its hardy noticable now.

I wish the seller had sent a manual as it may of helped or he should of explained it was adjustable it would of saved the hassle, anyway good new so thanks guys for all you input.