Rotary table

[Coomba]

I have been looking at different rotary tables, and I'm thinking this one from Little machine Shop might be the one to get. Asking what you guys use and why? Am I going to small, or maybe buying to much? I would like to learn how to make gears. Appreciate your input before I put my money down. http://littlemachineshop.com/products/product_view.php?ProductID=3792&category=1963256910

 

[Wizard69]

I'm not really the skilled machinist like many on these forums but that does look like an interesting set or parts.

The big problem that is see is the dividing head. The plates look darn right funny in the picture. Being no expert and considering the crummy photo, you might want to contact LMS for more information. You would want to know how many dividing plates actually come with the unit and the number of holes in those plates.

Beyond all of that more info on the size of you machine might be helpful. I'm sure the experts will want to know

I have been looking at different rotary tables, and I'm thinking this one from Little machine Shop might be the one to get. Asking what you guys use and why? Am I going to small, or maybe buying to much? I would like to learn how to make gears. Appreciate your input before I put my money down. http://littlemachineshop.com/products/product_view.php?ProductID=3792&category=1963256910

 

[petertha]

As far as a 4" RT goes for smallish jobs, I really like the Sherline I bought.
http://sherline.com/product-category/mill-accessories/rotary-tables-mill-accessories/

- seems quite accurate, low profile, use in normal or upright mode
- they have a neat thread-in center stub that then integrates their same lathe 3-jaw & 4-jaw chucks for quick grip/centering jobs (have a look at their capacity as they are also on the smallish side)
- its a conventional worm screw dial, not detant indexing if that what you were seeking. Easy/logical divisions.

Because it is low profile, I mounted a square baseplate for mine & grip the whole RT in my 5" mill vise. It sets up so quick I almost hate dragging out the larger RT now.

 

[Coomba]

I'm not really the skilled machinist like many on these forums but that does look like an interesting set or parts.

The big problem that is see is the dividing head. The plates look darn right funny in the picture. Being no expert and considering the crummy photo, you might want to contact LMS for more information. You would want to know how many dividing plates actually come with the unit and the number of holes in those plates.

Beyond all of that more info on the size of you machine might be helpful. I'm sure the experts will want to know

My mill is a PM450G, it has a 8 1/4" x 28 3/4" table. X travel 17 3/8", Y travel 11", Z travel 17 1/2" Spindle to table 20 1/2"

 

[chucketn]

I bought a 4" Vertex, but without the indexing setup. I lucked out and was given a the indexing setup including plates, handle and tail stock for the cost of shipping it to the US from England. I have since added an Arduino driven controller and stepper setup to it for gear cutting. Works great on my X2 mill

Chuck

 

[gus]

Given the time,one could build a 4'' D.H. with drawings from Taig Machine Tool Projects. Made mine successfully. As for the indexing plates,made it too with help from friends doing computer dividing print outs. DH is a twin bro. of LMS. Also made another D.H. using drawings from Harold Hall using direct indexing. Howell V-2 Gear Train were DIY Cut. Best to cut gears between centers for concentricity. Chuck are not best. Off Centered gears are hard to mesh.

The DH from LMS should be OK but to cut a wide range of gears,additional indexing plates required. Cutting Gears will be another skill to pick up. Be mentally prepared to collect some gears with 1/2 tooth. About 10 HMEM folks and Gus took up gear cutting and had plenty of fun. Metric Involute Gear Cutters can be sourced from China cheaply but quite good. However they do make Imperial Gear Cutters. Sourcing same from UK was very expensive.

 

[petertha]

My mill is a PM450G, it has a 8 1/4" x 28 3/4" table. X travel 17 3/8", Y travel 11", Z travel 17 1/2" Spindle to table 20 1/2"

I started answering your RT specific question, but maybe some added info would be useful. You have sufficient mill table real estate so you could go down 2 different paths, mostly influenced by anticipated work. For gear cutting I suspect most folks utilize dividing plates for accurate positional indexing. Dividing heads come with plates. You mount stock on their centers or integrate a chuck on the threaded spindle nose. The nicer imports like Vertex tend to cost about as much as similar size/quality RT. You can also typically pivot DH's for cutting bevel gears which is normally kind of a setup pain, but model engineers are resourceful & will always find a way.

Rotary tables for the most part don't come with plates, but some models do. You typically release or disassemble the worm screw handle & install plates. You probably should make that decision up front though as plates tend to fit only those specific RT models. Here is an import RT that includes plates (not pictured but that's what it says).
http://littlemachineshop.com/products/product_view.php?ProductID=3566&category=
I guess a conventional RT without plates can also 'rotate index' to nominal angular increments for gear cutting. You are reliant on hitting exact angular positions using the graduation lines (as opposed to holes in a plate). I cant tell you if this is accurate enough, haven't done gears yet. Some RT's have vernier scales for increased accuracy but anyway if your gears required oddball partial decimal degrees, you might be pushing the typical import jobbies. With RT's you can mill continuously through an arc like semi-circle slots. Plates require you to: move to specific angular position, do a machining operation, move to another position, repeat. Nothing in between.

You know how this story is going to end, eh? In an ideal world where money was no object you would probably have both! The other thing to consider is the related tooling, do you require chucks or collets or plates to hold the work you want to make. Check into those sizes & cost.

Hope this helps, god luck

 

[Cogsy]

With RT's you can mill continuously through an arc like semi-circle slots. Plates require you to: move to specific angular position, do a machining operation, move to another position, repeat. Nothing in between.

I have a Vertex dividing head and I can machine through an arc with no problems at all. I need to keep some small pressure on the handle to ensure it doesn't engage a hole in the plate, but it's exactly the same as when changing positions, except the cutter is engaged. If I couldn't machine an arc I'd never recommend a dividing head as that is the majority of the work I perform with it.

 

[petertha]

There you go, learn something every day.

 

[Charles Lamont]

I have a Vertex dividing head and I can machine through an arc with no problems at all. I need to keep some small pressure on the handle to ensure it doesn't engage a hole in the plate.

Does it not have a latching position by twisting the handle to hold it disengaged?

 

[Blogwitch]

Charles,

Before I modded my Vertex RT to a Divisionmaster setup, you could reposition the dividing location handle so that the locking pin just about sat around the outside of the division plate, so you used it just like a normal RT.

One of the main problems with an RT or even the Vertex BS0 dividing head, you would never get all the holes you required with the dividing plates supplied, in fact, with the Vertex there were many that just couldn't be obtained, mainly odd prime numbers. I spent a lot of time and money buying third party plates and modifying them to fit so that I could cut gears or drill holes in the counts I required.

I would suggest to anyone, if you have the means, to buy a basic RT and convert it to electronic operation with stepper control. With mine, I can get from 2 to 9,999 positions, and I can even use it to cut exact degree slots or full rotations very easily indeed.

John

 

[Wizard69]

My mill is a PM450G, it has a 8 1/4" x 28 3/4" table. X travel 17 3/8", Y travel 11", Z travel 17 1/2" Spindle to table 20 1/2"

I probably should have asked what size do you work in. In any event here is my theory, it is easy to have a rotary table that is too small but a rotary table is seldom too large if it sits neatly on the machine table. Given this I'd look for a slightly larger table.

Size your rotary table such that it can be easily set up with the T-Slot arrangement on your machine table. I'm not familiar with that machine so I'm thinking something in the 5-6 inch range will sit nicely on the table. Now you may ask why, go bigger, my first thought there is more flexibility in set up and what you can do with the rotary without putting on a sub plate. You might be able to go even bigger depending on the rotary and your mill table but do consider one thing: the big rotaries are very heavy. I wish I could put that in bold, we have some real old RT's at work that are a real pain just to move around.

Now we have a few other things to consider, if part of your goal is to do gears you may run into clearance issues with any RT. Imagine your involuted cutters running into the table or the mills quill. You can of course mount the gear blank on a shaft but that is least than ideal from a rigidity standpoint. However if small gears are your game you might want to make something like the Versatile Dividing Head outlined in the book Worksop Techniques by Geo. H. Thomas. This would be a supplement to the RT. In my mind a dividing head and a RT are two different accessories even though a rotary table arranged vertically can take on some of the stuff that a dividing head does.

In the end it is a matter of getting a handle on what you want to use the unit for. One thing you can do for yourself is to get some cardboard and cut out some circles of 4, 5 and 6 inches in diameter. Lay the circles on you mill table. I'm willing to bet that the 4" table will look puny to you on that table. Set up area increases significantly with each inch in diameter. As you may guess I'm thinking about the table mostly in the horizontal position. You will need to put a lot of thought into what you want to do in the vertical orientation. A RT may be just what you need vertical or it might be a total pain in the rear.

If it looks like I dwelled a long time on setup it is because it can be a huge pain to work with really small stuff. This can be the case on shop machinery of automation equipment. At work my focus is on automation equipment, handing very small stuff, it is a real pain if you have big hands. Everything becomes tedious to say the least. Of course if you are working on models that fit into the palm of the hand you have different considerations.

 

[Cogsy]

In my mind a dividing head and a RT are two different accessories even though a rotary table arranged vertically can take on some of the stuff that a dividing head does.

I've never had/used a rotary table and I'm not really familiar with them. What can you do with a RT that you can't with a dividing head? If there's enough reason to, I might consider trying to make one sometime, but not if there's no point.

 

[Blogwitch]

Cogsy,

The main difference is the amount of throat you have with an RT over a dividing head, especially on some of the smaller machines. The main advantage of a dividing head is that you can very easily set up angled cuts without resorting to angle tables or vices.

As most of you know, I use adaptive tooling (collet holders, chucks etc) to swap jobs between lathe and mill, including the RT and dividing head.

One of the advantages with what I have is that with a cheap Myford faceplate (less than 40UK pounds), I can convert my RT from 6" diameter to 9" within seconds.
There is nothing stopping anyone getting a bit of plate metal and making their RT larger, you just have to make sure the plate doesn't interfere with the handle or dividing gear.

A normal 9" RT would be much too heavy and bulky for my machine.

John

 

[goldstar31]

Agreed about the versatility of the Vertex Dividing head. I stuck with my old Myford stuff( probably advanced senility)

I discovered that it would all go on my Clarkson 1 T&C as well.

Unquestionably, John has the right idea.

Regards


Norman

 

[Wizard69]

I've never had/used a rotary table and I'm not really familiar with them. What can you do with a RT that you can't with a dividing head? If there's enough reason to, I might consider trying to make one sometime, but not if there's no point.

Generally when I think rotary table I think machining stuff with it arraigned horizontally. Imagine being able to rotate your current mill table.

When thinking like this you should realize that there are plenty of things doable on a rotary table that would be hard to do without on a manual machine. Anything that requires a radius to be milled are a candidate, especially arcs that can't be done on a lathe.

Sometimes you can do just as good maybe even better with a DRO, for example doing bolt circles. You can't however do continuous arcs with DROs.

In the tool room world rotary tables have been largely replaced by CNC machines. Even in the hobby world CNC solutions can often be cheaper than buying a decent rotary table. CNC can also be faster to setup in some situations, for example if you have to blend a bunch of arcs into other arcs or tangent to flat surfaces at odd angles. Of course CNC implies a CAD drawing and the ability translate it with CAM tools. CNC actually brings some other advantages to small machine tools over rotary tables, rotary tables cause you to loose Z height which is always a problem on small machines.

I guess I got off track here with the CNC stuff but it is a good alternative if you expect to do things normally done with the RT horizontal. Depending upon the complexity of the part and the documentation you got, though a manual setup can be faster. It is this issue of sometimes being faster sometimes not, that causes CNC to be dismissed in the hobby world as a RT replacement. I just threw this out because it is good to understand the alternatives.

Someplace in between all of the above are modified RT with electronic drives. One might describe such as a single axis CNC! Such upgrades can be highly recommended even if you never see a full blown CNC in your future. Electronic drive eliminates a lot of tedious indexing and can eliminate some of the mistakes that can be made indexing materials.

Probably a lot to think about here.

 

[Blogwitch]

With reference to Wizards last paragraph.
This has been shown before, but the vid explains things so easily.

[ame]https://www.youtube.com/watch?v=P1ifPuImERA[/ame]


John

 

[Cogsy]

Thanks for the replies. My mill, although not the most precise thing in the world, has lots of throat so I can set up the dividing head vertically and still use a coax indicator to centre the workpiece, so I guess I don't need an RT. I thought I must be missing some RT capability but if it's really just the size issue I don't need to worry about it. Just as well too, I have a list a mile long of tools I need/want to build already...

 

[Wizard69]

With reference to Wizards last paragraph.
This has been shown before, but the vid explains things so easily.


John

Thanks John, excellent video that should help a person understand rotary tables and their uses. Certainly better than my stumbling to find a verbal description.

It looks like your Division Master is one of those devices that is quick to learn as you mention only having it for two days. If so that is great because working with rotary tables manually, with or without dividing plates takes a while to learn and is error prone. There are a few open sourced solutions to making an electronic RT for those who seek a build it you're self adventure.

Probably the only thing missing is showing making tapered flat components. I like to call them pie sections.

 

[Blogwitch]

Wizard,

A few people on here have gone down the Arduino route for controlling their RT's, unfortunately, I can't get my head around them.
Supposedly they do much the same thing as my division master but at a much lower cost.

http://divisionmaster.co.uk/divisionmaster.html

John