What Rotary Table?

jmltinnc said:
Thank you for your clear answer. Maybe I am from the bigger is better attitude (but I really do know better)? Actually, I want to leave nothing on the table (no pun intended), so wish to go max as I can. I know that just about everything on these smaller mills is about the Z. The difference between a 6" and 8" RT height is about an inch. I ignorantly thought with 14" of Z to spare I could get away with it.

I stand corrected and thank you.

John
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Z vanishes at an alarming rate. The drill chuck, and the length of your drills eat Z, as does your rotary table and fixture plates. And of course your part. I guarantee you if you use a standard length 1/2" reamer on a part in a small mill like this, you will be wondering where did all the Z go. As in, there is no Z to spare, and that is NOT on an RT.

Generally bigger is better, but that applies to the machine. Too large tooling on a little mill is not better. We all have our reasons for getting the machines we do, like either starting out, or having to fit in a small shop.

Personally, I wouldn't put either an 6" vise or an 8"RT on a PM25 class machine both would be too big for the machine, in my opinion. From a quick look up, an 8" RT weighs more than double that of a 6" RT, and is approximately double the cost. Neither may matter to you, but an RT just isn't used that often. So get what you need, but not a lot more, because it is tying up your cash sitting there.
 
markba633csi said:
I hear often people have large rotary tables and they sit collecting dust
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I have both an 8" Eron and a 12" Index rotary table. The Eron has the X and Y adjustments and does eat up Z room because of its height. It comes in handy from time to time, but in the scheme of things it's used far less than the 12" Index. It doesn't have the weight and stability of the larger table. The Index gets used a few times a month while the Eron only gets used a few times a year. To be clear the Index was made by the Index milling machine company before they were bought out by Wells in 1974. I'm not sure if Wells Index ever made rotary tables.

I would guess the Eron weighs in the neighborhood of 35 lbs. while the Index is 125 lbs. I can easily carry around the Palmgren but put the Index on a hydraulic table to move it to and from the mill.

Here's an example of an Eron rotary table listed on eBay. Don't let the price scare you off. They often come up for $100.00 or less.
https://www.ebay.com/itm/225173028012?hash=item346d5bbcac:g:LTsAAOSwWvhjK5w0&amdata=enc:AQAHAAAAoHK+Q/M9TQHNVmGxy7vUp1h4Yk3fs6MhZRV9LknpG61DTBimrLyU57cscrqIM/mPWZBGIa6UYY6yZhK1D/Jpk5dgMQvcea0Y8PGzmxHWXxBP3khzVB2dOrL64Y99hkIntKqwZjgk0za6W4u2cGyFF36ysQX/aR3ZZy6eU6y0TpXWCr3dS5HYVUtUMGbO7FHkTeCWU380je2FEA+sZ8idUqw=|tkp:Bk9SR_S8rPeMYQ

On Edit:
Here's a link to a picture of an Index brand rotary table similar to mine.

www.hobby-machinist.com

Rotary table

Here's an example of a horizontal only rotary table/indexer. This one is not mine. Mine doesn't have the indexing option. : I'm not sure if anyone today still makes this type of table. I've never seen one that can be used both horizontally and vertically. I can bolt mine to a 15" angle...
www.hobby-machinist.com www.hobby-machinist.com

As Mentioned in previous posts something to consider is the fact that the less expensive and most offshore tables use plain bearings (bushings) as opposed to deep groove ball bearings. The plain bearings will wear more rapidly than ball bearings and can affect the accuracy of the table. The Eron I purchased was only about 10 years old at the time. It had been used to locate a label placing machine on a packaging line. As such it wasn't changing positions on a regular basis as would be necessary in a machine shop.

Even with the minimum use it got the bearings had to be replaced. It wasn't a big job, but one I was surprised it was necessary with such little use. The Index table on the other hand was built prior to 1971 and was still tight and accurate.
 
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projectnut said:
I have both an 8" Eron (like this one: https://www.ebay.com/itm/225173028012?hash=item346d5bbcac:g:LTsAAOSwWvhjK5w0&amdata=enc:AQAHAAAAoHK+Q/M9TQHNVmGxy7vUp1h4Yk3fs6MhZRV9LknpG61DTBimrLyU57cscrqIM/mPWZBGIa6UYY6yZhK1D/Jpk5dgMQvcea0Y8PGzmxHWXxBP3khzVB2dOrL64Y99hkIntKqwZjgk0za6W4u2cGyFF36ysQX/aR3ZZy6eU6y0TpXWCr3dS5HYVUtUMGbO7FHkTeCWU380je2FEA+sZ8idUqw=|tkp:Bk9SR_S8rPeMYQ) and a 12" Index rotary table. The Eron has the X and Y adjustments and does eat up Z room because of its height. It comes in handy from time to time, but in the scheme of things it's used far less than the 12" Index. It doesn't have the weight and stability of the larger table. The Index gets used a few times a month while the Eron only gets used a few times a year. To be clear the Index was made by the Index milling machine company before they were bought out by Wells. I'm not sure if Wells Index ever made rotary tables.

I would guess the Eron weighs in the neighborhood of 35 lbs. while the Index is 125 lbs. I can easily carry around the Palmgren but put the Index on a hydraulic table to move it to and from the mill.
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It's about matching your tooling to your mill. If your mill is relatively large, then yeah a bigger RT, can be quite useful. If you have a small mill, overwhelming it with tooling that is too large will lead to frustration or even the inability to use it. The OP has a small mill, like I do. We are limited in the size and scope of tooling that will work well on our mills. That's the performance compromise of smaller machines.
 
I guess my point is to go with a known brand that's built to a quality level beyond typical offshore offerings available today. Look for brands like Index, Troyke, Walter, Vertex, Bridgeport, Kurt or similar. These companies made rotary tables from 6" to well over 48". They were built to withstand the daily rigors production environments. The newer light duty ones will all but fall apart with any regular use.
 
projectnut said:
I guess my point is to go with a known brand that's built to a quality level beyond typical offshore offerings available today. Look for brands like Index, Troyke, Walter, Vertex, Bridgeport, Kurt or similar. These companies made rotary tables from 6" to well over 48". They were built to withstand the daily rigors production environments. The newer light duty ones will all but fall apart with any regular use.
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Agree with you.
 
Thank you for all the replies!

I totally understand the Z-axis stranglehold. And with all due respect I don't get the advice to buy a 6" RT and build an adapter for 8". It seems to me should I do so and want (nearly) the same stability and structural integrity as an 8", I need a thick adapter. There goes my Z right off the bat (except for when I don't need the adapter). I'm not made of money and cost IS an issue, but I think I would rather buy two tables - a 6 and 8 rather than build an adapter. I'm not married to an 8" RT but what have I wrong here?

I think my original question, "...what RT for this mill'''" has been answered - it is all about the Z. Is that a correct statement? If true, extend the question to: I have a 4" Kurt-style vise and my Y travel is far more than the 4" opening. Should I have a 6" vise for this mill (same question - different attachment)? I think this rhetorical point holds. But I am a Newb and hold no ground in my thought experiments.

It is ironic that the radius I need to cut is 4", on a 1" thick x 4" wide part. It is an inside (concave) - please correct me on terminology!!!, and even the 8" RT is too small to hold the part. Luckily the stock is plastic so I will use a boring bar with the stock spaced above the bed. There is a challenge there too, for the stock is 4" wide making the sagitta 1/2" - leaving 1/2 inch to clamp. I think doable, but what do I know? I will find out though...

I am not trying to be argumentative, but I am full of questions that may seem stupid to the experienced. I am sorry for that. I am eternally grateful for all replies I get. I take everything in everything and think.

John
 
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