View Full Version : Worm Gear pillage
07-23-2009, 09:31 AM
I am thinking about making a rotary table. I was just wondering if anyone knew where I could find a good worm gear?
Like I have said in a previous post I have been able to make an acceptable manual rotab, so I am thinking my next best bet would be to make another one but better.
07-23-2009, 09:34 AM
I'm chiming in before HE gets a chance, have you checked his holiness's site, division plates too.
Regards Ian. :D
07-23-2009, 09:40 AM
as you can tell by my post count that I am a newb and thusly am un aware of the site with which you speak.
07-23-2009, 09:48 AM
Sorry, the illustrious Sir John Stevenson, (Did I spell it all correctly John???)
No connection whatsoever, just another dissilusioned fat chewer.
Regards Ian. :rolleyes:
(PS. Look on the bottom of one of his postings for the site)
They aren't hard to make. I have made quite a few including this one. This is 7075 alumimnum, slightly harder than steel. Bronze is a good choice and easy to machine although a bit expensive in the larger sizes. Steel works fine but requires a tool steel hob, not a big issue if you can harden it.
Shown is the wheel and the hob used to cut it.
07-23-2009, 10:00 AM
hello evan could you please make me one and send it to australia?
07-23-2009, 10:46 AM
You got mail Michael
07-24-2009, 10:25 AM
was a good day,
I got a reduction gear box to use as a guts to my rotab. I was thinking of building a box for it and arranging some kind of thrust bearing system for it.
I was thinking that why don't I just make an adapter and bolt the chuck straight onto the output shaft, add a dial to the input shaft and bobs your aunty..
does anyone know if this box could handle the loads placed on it when used beneath a milling machine to cut radii etc?
Just putting it out there......
Looks like a 6206 bearing on the input shaft and a larger deep groove bearing on the output. It looks pretty stout to me. It should work. The only concern is damage to the bearing from shock loads. Ball bearings have a much lower allowable static load than dynamic load. They are a lot easier to damage when they are not turning.
07-24-2009, 10:51 AM
thanks for the reply evan,,
I was just looking at this picture here
at it looks basically the same.... add a handle and away I go.
as long as the output shaft has limited movement (side to side, in and out) I cant see it being any worse than a cheap import.. If problems arise I could always redesign parts of it.
07-24-2009, 10:56 AM
it also has machined faces on all size sides so it could be a vertical as well.
It really does seem like a good idea, it will cost me only $60 its 160mm square so I would attach maybe a 6inch chuck....
One thing, just because it has machined faces on all sides doesn't mean they are square to each other.
07-24-2009, 09:31 PM
I will put a mic on it when I get it just to make sure.
07-24-2009, 09:43 PM
Good on you.
Its nice to see someone "having a go". The basics are there. Its just a matter of sorting what the threads are and getting them all together.
Providing the "guts" inside are OK -worm and wheel - and the gear-box is as solid as it looks, you are "right to go".
The worm ratio is not important at all. There are lots of "main-stream" rotary tables out there with a whole range of ratios 40, 60, 72, 90 etc. A set of tables and indexing plates (if you need them) can soon be quite easily worked out for any - and I mean any - ratio and made to suit. Its easier if the ratio is a sub-multiple of 360 - for a whole lot of reasons - but it can be "lived with" or "worked around".
The "shape" of a rotary table is NOT important but its functionality IS important - the choice is yours.
The level of functionality you require and the work that you can or want to do will be an inevitable compromise, but that too is for you to decide for yourself.
I guess that this is is going to be an evolutionary project and a "work in progress" for a while yet.
So - get in there, get started and make go of it. You have nothing to lose and a lot to gain in many ways.
I admire your courage and tenacity.
07-24-2009, 10:16 PM
Making a rotary table is alot of work. you can make a pick-up truck too if you want but its way less work to buy a quality unit.
I would punt on that project. look at some auctions.
07-25-2009, 01:34 AM
mike most of the work is done, Making one from scratch is hard yes I agree. This gearbox is brand new, and I would assume that the gearing inside would have to be on Parr with what is inside normal rotary tables.
All it needs is some feet, somewhere to clamp it down, a machined shaft to attach a chuck and a handle. If side loads are an issue I will bolt a plate and put some thrust washers underneath the lathe chuck.
Thanks for all your feedback,
07-25-2009, 03:30 AM
I would have thought the gearbox's insides would be many times better than the cheaper end rotabs as they are designed for a much higher duty life.
I was surprised at the insides of my rotab in that it was not designed for high levels of rotary life quite crude in fact personally I think I would prefer the gearbox option an opinion once expressed by sir john imself
07-25-2009, 05:47 AM
I have been thinking, using google sketch enables me to show what I am on about. I will have the shaft made by a shop, and I think this method would allow a fairly high degree of accuracy.. I drew a photo of it :)
this is by no means a cad drawing just an interpretation
07-25-2009, 08:13 AM
A big objection to using a right angle gear box for a ro-tab is the
inability to release the drive to turn the table a large angle. Depends
on hof often it usd in that mode versus just incrementing around
the whole circle. The times I've used one it has been very handy to
disengage and turn a long way and then reengage the gears.
Otherwise looks like a winner.
07-25-2009, 10:05 AM
my main goal is to machine a circle :)
plus if it takes an hour to spin the table around no loss really my times not that expensive, if it was I would just buy one.
I would be very happy if I ended up with something that was fairly sturdy and usable... Unlike a cheap Indian one that looks good but is a piece of crap. I am getting steel tomorrow so I will post some more photos.
07-25-2009, 12:18 PM
here is an exploded view, I am still a bit unsure about whether I should make it so that a chuck mounts straight on it or use a back plate.. I need to know this to get the thread cut.http://i92.photobucket.com/albums/l13/mickstar_2006/sploded.jpg
07-25-2009, 02:39 PM
Have your requirements changed Michael? From Rotary Table to Rotary Chuck??
Reason for asking is that on a Table, the chuck is supported by the greater face contact of a table. What you are proposing has the chuck swinging on a shaft which for milling etc. looses lateral support.
07-25-2009, 11:24 PM
I would have thought that the shaft and the spacer would provide adequate lateral support?
the main reason for my pictures is to provide some extra support for the gearbox bearings.
The chuck wont be far from the table.
Maybe I could build like this but have the chuck base bearing on the top plate?
Machining in a chuck on a shaft works pretty well for a lathe. Works well on my 4th axis too.
07-26-2009, 04:05 AM
Ok having put some thought into it, I think I have a better Idea, this will result in having a more conventional backplate, and the use of a ball/tappered bearing
there's two pics they show everything basically.
07-26-2009, 04:08 AM
the square bit will bolt to the gearbox and the round plate will be a back plate.
07-26-2009, 05:28 AM
Machining in a chuck does work quite well in a lathe, but do we REALLY have to start ANOTHER bearing war???
we REALLY have to start ANOTHER bearing war???
I think I will post a new thread. This has brought something to mind.
07-26-2009, 09:57 AM
so wat do ya reakon? this a better idea?
07-26-2009, 10:41 AM
The only problem I can see here is that there will be no way of centering the chuck.
12-12-2009, 09:29 AM
whelp I made it. I ended up using a common back plate set up for it. The shaft that runs through the gear box extends past the back plate and is turned down to the ID of my lathe chuck.
The main shaft is a "tight" fit inside the gearbox and the back plate yet I still had about 12 tho runout around the outside of the back plate. There could be a few reasons for this but I am not really bothered by it because I can eliminate the runout by adjusting the position of the chuck on the backplate.
(once I pop the chuck of and reduce the diameter of the through shaft, so I can get a little more adjustment)
I managed to get it down to about 12tho runabout at the chuck. Until I am faced with a project that needs more accuracy I will just run with it. Hell I could even just spin the back plate against an end mill.... that'l true er up. I will make a nice handle for it one day.
I punched marks in the dial at 90 deg intervals I will knock up a pointer for it. its a 40 - 1 box so with the extra marks That then gives me 160 divisions of the 360 degrees.
I will lighten some rods with it tomorrow and post some more photos.
12-12-2009, 09:31 AM
I will also make some better hold down clamps or something for it too.
I have an 8 inch faceplate that I will stick on so I can grab the bigger stuff..
12-12-2009, 10:09 AM
Nice uage of materials and existing equipment, simple construction, but kinda tall isn't it?
12-12-2009, 12:01 PM
Nice uage of materials and existing equipment, simple construction, but kinda tall isn't it?
yes it is tall. The bearing surface underneith the back plate could be reduced by about 2/3 and the backplate could be reduced by about half.
If I did both those things and used a faceplate it would be plenty low enough.
If I have a problem with clearance I will mill some meat of it...
12-13-2009, 08:42 AM
I did some tweaking today and managed to get runabout to around 3 tho with some tool steel in the chuck. Works fine see