Rotary table

[AlbertdeWitte]

Hi Guys

I have the Vertex HV6 with indexing plates, 4"Chuck and tail stock which I find to be quite fine, I would love to add the Division master to it one day. I am sure it can be fitted with a few mods, what do you think?

 

[rodw]

Hi Guys

I have the Vertex HV6 with indexing plates, 4"Chuck and tail stock which I find to be quite fine, I would love to add the Division master to it one day. I am sure it can be fitted with a few mods, what do you think?

You dont need to spring for the divisionmaster when there are some excellent solutions right here on this forum..

Here is the DIY stepper kit for a Vertex table.

http://www.homemodelenginemachinist.com/showpost.php?p=262292&postcount=103

 

[Wizard69]

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

Division master seems to have well thought out software and is a complete product. That in itself would justify the hardware to many people.

As for the open source stuff you really need to be of the type of person that likes to tinker with software and electronic hardware. I'm not sure which route I will go. Right now it is very difficult to budget anything for the home shop.

 

[Blogwitch]

I am not pushing anyone towards the division master, just giving people the info if they want to go down that route, I personally wouldn't know where to start with Arduino, and I think there are a lot of people like that.

It just might be like the DRO saga, buy cheapo scale units and end up spending more money and time trying to get it accurate and reliable than it would have cost to buy a glass read head unit in the first place.

Rod,

You have only shown half the job on that link, where are the thrust bearings that get rid of most of the backlash inside of the Vertex head? It is easy just whacking on a stepper, getting rid of the shaft backlash is a whole new ball game.

This is how I got around the thrust bearing problem on the Vertex 6" and smaller. Thrust bearings aren't available in the correct size, so I made a pair from sintered bronze that do a great job.

On the expensive ones from Arc Euro and LMS in the US, the proper sized thrust bearings are available, and it was much easier to mod that type of RT. But it wasn't just thrust bearings that were fitted, needle rollers were fitted inside the offset bored shaft carrier as well, to take the side loads from the worm.

Without doing that mod, you can only really send the RT in one direction so that it takes up the worm and wheel backlash, unlike mine, which works very accurately in BOTH directions because of no detectable backlash.

John

 

[Coomba]

Lots of good information here. I have much to consider. Thanks

 

[Coomba]

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

That was the first RT. that I considered, but didn't think I could handle the weight. The second was also from The Little Machine Shop, but is a four inch,and is much less in weight. There is a link to it in my original post.It also has a Chuck, dividing plates,and a tail stock.

 

[Buchanan]

I have used many RT's over the years. From home built to repairing thrown out, to new. one thing I would not be with out is my Divisionmaster. It takes out at least half the stress in cutting gears. Vertex are a good economy RT and very respectably accurate. Divisionmaster is also very easy to fit. I gives the ability to power feed as well as take up backlash. The ability to cut any number of teeth, or index any angle is a great advantage and it almost totally removes the potential for counting errors or slips. There is very reasonable tooling available from CTC tools. I would recommend a ER collet chuck to fit the taper in the table as well as a 3 jaw chuck as both greatly extend the usefulness of a RT. Next better is CNC, but that is another ball game.

 

[AlbertdeWitte]

Great post John with clear guidelines!!

 

[Wizard69]

That was the first RT. that I considered, but didn't think I could handle the weight. The second was also from The Little Machine Shop, but is a four inch,and is much less in weight. There is a link to it in my original post.It also has a Chuck, dividing plates,and a tail stock.

That listed weight might be for shipping the entire set of components. In any event you are right to be concerned about weight, these tables get heavy fast. It is a good reason to consider installing a jib crane of some sort or another lifting aid. Guys have come up with all sorts of aids to get vises and RTs off a mills table. The last thing we want are lifting injuries while engaged in a hobby.

You still need to think about how this table will be used. For some uses a big RT gets in the way in vertical mode.

 

[Blogwitch]

I have had my RT and vice (soon to be a larger more versatile vice) both fitted at the same time for the past few years, and haven't come across any problems where I need to remove both of them at the same time. In fact, it is a bit of a squeeze, but I can also mount my angled vice on there as well at the same time.
It took a bit of working out and fiddling with positioning, but things work just perfectly now. It saves hours on setup times

The only time I would ever have to move them off the table was if I needed to fit my dividing head, in which case only the RT needs to be moved, or the job was so large, I would have to use my 2 piece vice along the table. The last time was when I was machining out the back side of an electric guitar, not the sort of job that comes along very often.

John

 

[rodw]

Rod,

You have only shown half the job on that link, where are the thrust bearings that get rid of most of the backlash inside of the Vertex head? It is easy just whacking on a stepper, getting rid of the shaft backlash is a whole new ball game.

John

I don't see backlash being mechanical factors within a rotary table has anything to do with stepper motor control. My RT had no appreciable backlash so I did not bother with backlash compensation within the software. For super precise stuff, the operator can choose to turn one direction only.

 

[Blogwitch]

Everyone to their own Rod, and if you can work with it in one direction, then fine.

The problems arise Rod when you need to cut slots that maybe travel backwards and forwards half a dozen times. In your situation, you will have to lift the cutter, advance however many degrees to the start of the slot and start cutting again, repeat as required. For making things like flywheels, it is perfect as you get no over-run, a thing I used to suffer from when making them on a manual RT.

As I said, each to his own, I only raised the point because it really is a thing that needs to be done if you are searching for repeat accuracy with your RT or dividing head. I haven't as yet modded my dividing head, but it will be done, eventually.

If you don't eliminate that backlash you will forever be restricted to one accurate direction only.

The inner shaft on my Vertex with sintered bearings is at most 0.001" end float, just enough to allow the shaft to rotate without binding, and on the AE ones, no end float at all, as they use roller bearing thrust washers and it can all be adjusted out.

On the second one I showed, the high priced Arc Euro one, that is almost exactly the same mod done by AE on their 4th axis CNC RT's, but I use mechanical fixings on the stepper coupling tube rather than a Loctite approach.

http://www.arceurotrade.co.uk/Catalogue/Workholding/Rotary-Tables/4-Rotary-Table-with-Stepper-Motor

For the extra couple of hours machining and the few bucks it takes to do the mods, it is well worth it in the knowledge that you have an RT that can be used accurately in both directions without having to turn back and move forwards again to eliminate your backlash and get to where you were in the first place.

John

 

[Coomba]

Everyone to their own Rod, and if you can work with it in one direction, then fine.

The problems arise Rod when you need to cut slots that maybe travel backwards and forwards half a dozen times. In your situation, you will have to lift the cutter, advance however many degrees to the start of the slot and start cutting again, repeat as required. For making things like flywheels, it is perfect as you get no over-run, a thing I used to suffer from when making them on a manual RT.

As I said, each to his own, I only raised the point because it really is a thing that needs to be done if you are searching for repeat accuracy with your RT or dividing head. I haven't as yet modded my dividing head, but it will be done, eventually.

If you don't eliminate that backlash you will forever be restricted to one accurate direction only.

The inner shaft on my Vertex with sintered bearings is at most 0.001" end float, just enough to allow the shaft to rotate without binding, and on the AE ones, no end float at all, as they use roller bearing thrust washers and it can all be adjusted out.

On the second one I showed, the high priced Arc Euro one, that is almost exactly the same mod done by AE on their 4th axis CNC RT's, but I use mechanical fixings on the stepper coupling tube rather than a Loctite approach.

http://www.arceurotrade.co.uk/Catalogue/Workholding/Rotary-Tables/4-Rotary-Table-with-Stepper-Motor

For the extra couple of hours machining and the few bucks it takes to do the mods, it is well worth it in the knowledge that you have an RT that can be used accurately in both directions without having to turn back and move forwards again to eliminate your backlash and get to where you were in the first place.

John

I can see where a stepper motor would be a big plus, but right now,I think I need to crawl a bit,before I step up. Can we talk a little about division plates? How do I determine how many to buy,and which ones I will be needing? Also would a four jaw Chuck be better option than a three?

 

[rodw]

I can see where a stepper motor would be a big plus, but right now,I think I need to crawl a bit,before I step up. Can we talk a little about division plates? How do I determine how many to buy,and which ones I will be needing? Also would a four jaw Chuck be better option than a three?

Just buy a dividing plate kit for the rotary table you choose. Here is one to suit the Vertex 4" and 6" tables http://www.machineryhouse.com.au/R016

And there are complete kits with the chuck as well. http://www.machineryhouse.com.au/R016

You can see this has a mounting plate to hold the chuck that sits on a tapered spindle so it is quick and easy fit the RT. The alternative is to bolt the chuck directly to the T slots on the table and you can buy a t slot bolt kit to do this as well. There is a setting up issue.

Some people set up so they can move the chuck from their table to their lathe.

A quick and dirty method of locating the table is to place a taper in your mill and engage it in your table. I found that this was still a fair way out when checked with a coaxial indicator so to me it is just a starting point.

I think the 3 jaw chuck is the way to go. Centreing something in a non rotating 4 jaw chuck might not be very easy!

 

[Wizard69]

I can see where a stepper motor would be a big plus, but right now,I think I need to crawl a bit,before I step up.

Probably not a bad idea . Many people get frustrated with division plates, it takes a lot of focus and a bit of math to do a part from beginning to end without error. I suspect most people have screwed something up with a rotary table.

Can we talk a little about division plates? How do I determine how many to buy,and which ones I will be needing?

There is no way to really answer that because what you need varies with what you are doing at the time. Some times guys end up making their own plates. Before going to far I'd suggest finding a book that dives into the use of these RT and other indexing systems. Once you get a handle on it, the math is focused on ratios, you will find the knowledge useful for indexing things beyond rotary tables. For example you can index a lathe spindle in the same manner as a RT.

Also would a four jaw Chuck be better option than a three?

If you only have one, the four jaw will be preferred. If you are going to do gears, you will want to be able to dial in concentricity to with in a couple of tenths. Of course you may be able to dial in the 3 jaw but it depends upon how you mount the chuck to the rotary table. So to an extent the answer here depends upon the specifics of the chuck / RT combination.

By the way not to confuse things but the chuck needs to be concentric (hold a part concentric) to the axis of rotation of the rotary table. This is different than setting up the spindle to be on center with the RT rotation axis which can be required for some uses.

 

[Blogwitch]

Sorry to have displaced your original post by giving information about powered RT's, but it might have helped someone to understand things better.

Anyway, back to your problem.

If you buy say a Vertex RT, then as already mentioned, you can buy division sets that bolt almost straight on, but a word of warning, if you do fit one, don't lose the little keyway key when you remove the main handle, tape it to the handle for safe keeping.

As with any dividing set, you just can't get enough hole sets on the three plates that are supplied, so there will be some holes or divisions that you just can't get. Most people go through life with just those supplied plates, but if you are into gears then it just might be you will hit on the plates that just don't have what you require. I spent many hours going through what numbers were on the plates to find out what numbers I needed to get.

If you go to page three of the downloads section, about half way down, you will find that I have put up 'Vertex Charts'. If you download it, it explains how to do your indirect indexing and on the charts, what holes you can or can't get. You won't be able to do Differential indexing to get the holes you want as that only comes with gears on the more expensive Dividing Head.

So now down to your problem.

Say you need X number of teeth on your gear, and you don't have the correct hole numbers on your plate to get it, there is only one easy way to do it.
Find someone with a powered RT and get them to make a plate for you with the correct hole set on it. In fact, get them to put more hole sets on it for all the other numbers you can't achieve.

Years ago, I went the hard way as at the time you could buy punched plates with all different numbers on them, it was just a matter of cleaning them up and adapting them to fit the dividing set. I don't think they still do them, and I gave away all my modified plates to a friend when I converted to power otherwise you would have been quite welcome to them.

Sorry to have been so negative, but I do hope what I have said will help.

John

 

[goldstar31]

Arguably, the best book is actually two. The classic English model engineer George H. Thomas wrote and described his workshop tools in Model Engineer. Actually, it was the late Professor Dennis Chaddock, designer of the Quorn tool and cutter grinder encouraged GHT to do this. If you add 'Ned' Westbury, Tom Walshaw writing as Tubal Cain and Kenneth Cleeve Hart writing as Martin Cleeve, one has a pretty heady mixture of talent. When Thomas died, Neil Hemingway of Hemmingwaykits encouraged Dr Bill Bennett - a fellow student with my late wife to complete the intended books.

These became the Model Engineers Workshop Manual and Workshop Techniques. The latter embodies the earlier Universal Pillar Tool book and Dividing and Graduating.

So George starts with a basic little rotary table which hadn't any of these complicated ball bearings and even degrees around its perimeter to perhaps the most sophisticated dividing head which contained not one worm wheel but two to do ANY configuration.
To mention the construction of division plates, Thomas describes how he drilled his with a pair of dividers but goes on to described what can be achieved with a division plate with ONE hole.

Somewhere, under a heap of rusting metal- my workshop roof came off- are my Quorn and assorted GHT 'goodies' Nearer and probably just as inaccessible is the knowledge of how I tried to copy the 'Words and music'

There you have it

Norman

 

[ShopShoe]

Coomba,

I Just went back to your original post. On your original link, click “Chris’s Tips” and read the instructions for using the dividing plates he has posted at LMS. Think through a part or gear you want to make and see if you think you could follow the instructions to use a division plate to make that part. You may have to read the instructions more than once: I did, but my first attempt at a gear turned out OK except the gear blank slipped while cutting and made the infamous half-tooth. Second one turned out well and is still working after three years and hundreds of hours of operation. The main skill in doing this being able to concentrate through the boredom that comes with lots of cranks and lots of re-indexing the sector arms.

I bought my division plates with my rotary table almost by accident: I originally did not think I would be doing that type of work. It was only a few weeks later that I found myself using them. You will not be sorry if you buy them, unless you buy the electronic option from day one.

Only my two cents worth,

—ShopShoe

 

[petertha]

Speaking of dividing head, I thought it might be a neat accessory to have an ER collet on the end for quick round stock setups. I cant recall the thread, maybe 1.5x8 tpi? Has anyone made such an adapter?

 

[Blogwitch]

Peter,
They are fairly easy to make, just cut the internal thread for the ER adapter first, matching the nose thread on the DH, then make up a blank thread on your lathe to match the nose thread of the Dividing Head.
Without removing the threaded nose from your lathe chuck, screw on the ER adapter and cut away as I have shown here.

http://www.homemodelenginemachinist.com/showthread.php?t=24123

That way, you should end up with a fully concentric ER nose adapter.

BTW, I cut the internal thread to match the Myford nose I had made for my RT in that post, plus I also made the adapter to turn my lathe from a D 1-4 into a Myford nose thread for doing this sort of interchangeable tooling.

John