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View Full Version : Rotary table or spacer/divider???



gizmo2
01-21-2012, 04:04 PM
I'm sneaking up on the purchase of one of these beasts, probably of the 8" variety. I don't know enough about them to appreciate the differences. I'm shopping used, and for about the same price, the spacer/divider includes a 3 jaw chuck. So what are you giving up in return? Do any of you have both? Prefer one to t'uther? Any light y'all might be willing to shine on this would be greatly appreciated. It's a bunch of money, so I'd like to know more before taking the plunge. Thanks!

uncle pete
01-21-2012, 04:28 PM
It all depends on your type of projects, A spacer is normally faster and easier to use. A R/T is far more versitile and especially so with dividing plates. A spacer doesn't have any form of geared rotary motion, So other than straight dividing it's useless for rotary type milling. The R/T will give you far more divisions than a spacer will. My personal biased opinion would be to go with the R/T. And if your mill is large enough? I'd go with the 8" that you mentioned. You also want the horizontal, vertical type.

Since three jaw chucks aren't all that accurate as far as runout, Then it's not a great selling point IMO. If you ever need higher accuracy? Then a collet set up or a slower and more accurate independant 4 jaw would be better.

Pete

HAP
01-21-2012, 04:47 PM
I got one of the intergrated RT/Spacer combo's in 8". Does both funtions.

Rosco-P
01-21-2012, 06:21 PM
What is your intended use or uses? That will guide your choice.

gizmo2
01-21-2012, 07:12 PM
Well, for now Roscoe, just simple dividing. But I am getting deeper into model making, and the complexity is increasing with each project. I hope to be able to cut gears in the future. Uncle Pete's comment on rotary milling sounds like it might be a useful function in the future as well.

SGW
01-21-2012, 07:20 PM
I agree with Uncle Pete. If the choice is one or the other, a H/V rotary table will be the more versatile, if not always the most convenient. But as others have said, it depends on what you are going to do. If your needs are limited to making 2, 3, 4, 6, or 8 divisions to make square or hex heads on bolts or to drill bolt circles, a spacer will do that...and more, of course, but the number of possible divisions is restricted.

If, however, you want for some crazed reason to make a 59-tooth gear or something like that, the spacer almost certainly will not help you.

A spacer is limited in the divisions it can do. A rotary table isn't, though doing something like a 59-tooth gear by degreess-minutes-seconds would get pretty tedious. But if you needed to, you could do it. If you can, get a rotary table with index plates.

[edit:] Yes, rotary milling is A Good Thing to be able to do.

Rosco-P
01-21-2012, 08:35 PM
H/V rotary tables can eat up a lot of spindle daylight when used in the horizontal mode and long work needs the support of a matching footstock for rigidity. They are also heavier due to the right angle "foot". A "regular" rotary table can be pressed into horizontal service by bolting it to an angle plate. A H/V rotary table is no substitute for a dividing head.

oldtiffie
01-21-2012, 08:35 PM
Those rotary tables-cum-divired are neither lightweight no cheap.

Here are the specs for the 8" and 6" models.

https://www.machineryhouse.com.au/R004

https://www.machineryhouse.com.au/R002

Centreing the job or the 3-jaw chuck is not a problen as the chuck is front-face mounted and there is plenty of "play" ("slop"??") for adjustment.

I had the 8" unit and gave it away as it was too heavy and cumbersome.

I prefer to use my 6" rotary table as I can mount a 5" 3-jaw chuck (front-face mounted as before).

I disengage the worm from the worm-wheel so that the rotary table can "free wheel".

I always start at the table zero "0", move it the required amount, clamp the table, do what-ever and move on etc.

Most stuff that is "indexed" is equally divisible into 360deg eg. 2 divisions = 180 degree, 3 divisions = 120 deg, 4 = 90 deg, 5 = 72 deg, 6 = 60 deg, 8 = 45 deg, 9 = 40 deg, 10 = 36 deg, 12 = 30 degree spacings etc.

Lining up the fixed zero "by eye" to what ever "degree" mark on the rotating table you require is easy and if done carefully is very accuate and will meet most requirements.

uncle pete
01-21-2012, 10:11 PM
Oldtiffie,
You guys in Australia are getting severly hosed at those prices. Compared to the U.S. Were also getting screwed in Canaduh. Just not quite as bad as OZ.
But if I'm going to need to shift the whole chuck to get it concentric? Then you may as well use a independant. For multiple parts with the exact same diameter? Then yes a 3 jaw. When possible, I'd rather do the work between centers. A 3 jaw won't hold squares while a 4 jaw will hold that and round stock along with about any shape you can think of one way or another.

I'll also agree with Rosco, For just straight dividing, A proper dividing head is better. And if you need it, There's semi and full universal dividing heads for doing compound indexing along with the ability to do helical milling with the universal. And he's also 100% right about the need for a tailstock for longer work on any head system whether it's a Indexer, R/T, or a D/H. I should have mentioned that to begin with.

Pete

Rosco-P
01-21-2012, 10:22 PM
Really, an indexer, rotab, super spacer or dividing head is just another toy. Unless you are a production, semi-production or job shop, a toy that will spend a good deal of time sitting on the shelf. Do you really need it? Is there another way to get the job done?

dp
01-21-2012, 10:40 PM
The dividing head has the innate ability to present the rotating surface and angles between 0 and 90 which the R/T does not. Adding a tilt table under an R/T removes some of that head room you mentioned. At some point in making things you may wish for both. If one or the other can do both jobs adequately that would be the tool I'd buy first. Going back to the well for the odd job may be needed, but will happen later than sooner. The third option is a tilting R/T, of course.

oldtiffie
01-22-2012, 12:32 AM
Here is one with the lot - tilting table and all:

https://www.machineryhouse.com.au/R026


6" rotary table on a tilting table:

http://i200.photobucket.com/albums/aa294/oldtiffie/HF-45%20Mill%20misc/HF45-4-1.jpg

dp
01-22-2012, 12:37 AM
Here is one with the lot - tilting table and all:

6" rotary table on a tilting table:



Bit OT, but I'd like to have the inverted form of that table so the work remains closer to the cutter when changing angles. I have a similar table - no worm screw, and it is more useful on my small mill when uses upside down.

Rosco-P
01-22-2012, 08:47 AM
buying stuff you don't really need or understand how to use.
http://bbs.homeshopmachinist.net/showthread.php?t=52069
For the job, a simple indexer or even cheaper a spindex would have done the job. For that matter, some time, math, Dykem, dividers, scriber and prick punch would have got the job done a lot cheaper.