Author Topic: Building the Division Master and modding my RT  (Read 50632 times)

Offline madjackghengis

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Re: Building the Division Master and modding my RT
« Reply #25 on: December 22, 2010, 10:25:49 AM »
Hi John, I'm looking forward to seeing the finish of this project, and seeing it put to use.  As you do, I intend to extend my useful working life by such measures, and not be stopped in my working pleasures by physical infirmaties.  I've got a cam blank bolted to my rotary table, waiting for me to either machine the cam manually or put a drive on it and do it with accuracy and power.  From the sound of it, you should be ready to show us how it's done most ricky tick, and turn on the light for us out in the dark. :poke: mad jack

Offline Bogstandard

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Re: Building the Division Master and modding my RT
« Reply #26 on: December 22, 2010, 10:49:08 AM »
Nick,

It isn't just this that I dropped.
A while back I had just finished a lovely running and blinged up stirling engine, and as usual, without thinking, I picked it up with my right hand. It is now sitting in a box waiting to have a new built up micro crankshaft making.
Something like this happens weekly with me. This time, Lester came to the rescue, I can't thank him enough.

Jack,

Whoa!!! slow down a bit. I'm still waiting on a piece, when that gets here, I will do my best to get things moving again.

Your problem is the same as mine, and when I played about with the programming, turning either way by just pressing a button was one of the first things I learned to do. I can see that bit of the program being used a lot. It only took a couple of minutes to pick up how to do it, no mind numbing or long winded procedures to follow.


John
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Offline arnoldb

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Re: Building the Division Master and modding my RT
« Reply #27 on: December 22, 2010, 11:33:27 AM »
Thanks for showing your modification John; I'm sure it will be very beneficial to your shop time.

Once you have it going, it would really be appreciated if you could do a post-up of how it works and performs in operation; Ive noticed that it has no direct feedback mechanism to provide positioning information back to the controller, so I assume that the software will have a feature to set up for backlash calibration and compensation and so on; hence my interest in your operational findings.

I've had a look at the features available for using a motorized RT and was quite surprised by what I saw. It could be really handy, and is worth a definite consideration in future - once I've mastered some more manual operations to improve my own feel and experience.

Kind regards, Arnold

Offline Bernd

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Re: Building the Division Master and modding my RT
« Reply #28 on: December 22, 2010, 12:24:35 PM »
Sorekiwi,

Thanks for the reply. Going to follow Bog's suggestion.

Bog's,

I'll check out those threads you mentioned. Didn't follow them that closely. Interest wasn't there at the time. As I sit here surrounded by my shop I got to thinking of what projects I wanted to do. Seems like all needed some kind of tooling. Next question was, do I make it or buy it. Looks like some will be bought and some made in the shop.

Bernd
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Offline Bogstandard

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Re: Building the Division Master and modding my RT
« Reply #29 on: December 22, 2010, 12:30:49 PM »
I have had a short look at that part Arnold.

It does have backlash compensation, for the times you have to go back and forth. On the return journey, it overshoots the start mark by whatever amount you wish to enter, then it winds itself to the start mark again, ready for the next cut, and taking out the backlash. Of course, while this is all happening, you would retract the cutter if you were doing a slot.
I want it to cut both ways, for making deep slots, and for that reason, I need to eliminate as much backlash as possible, and hopefully, it will be close enough to what I want without using the backlash compensation. Or if it won't do it, only use backlash compensation on a final cut sequence.

I will do my best to put it thru it's paces, but other projects are pulling me ever and ever harder towards them, and I expect a lot of my learning curve will be done 'on the run' while working with other projects.

The operational and programming manual is very good, and really it is a matter of using your imagination as to what it could be used for. Each time I look at the thing sitting on my kitchen table, I think of another use it could be put to, and go back to the manual to see how it can be done. It really is a lot more than a precision indexer for drilling holes.

That is another thing I need to mention. This unit can be used on unmodified RT's, you just need a method of getting the stepper to turn the input shaft. I will be modifying mine, not only with a thrust washer system, but with a home made Oldham coupling end that screws onto the spindle rather than using the plain portion where the normal turning handle fits. So there is no need to follow my internal mods at all if you don't want to. I am just trying to squeeze every bit of backlash out of mine. It might work, it might not, but unless you try it, you don't know if it will succeed.


John
If you don't try it, you will never know if you can do it.

Location - Crewe, Cheshire

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Offline shoey51

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Re: Building the Division Master and modding my RT
« Reply #30 on: December 22, 2010, 01:30:08 PM »
I too will be interested in seeing it in action.
Great work as always Bogs :thumbup: :clap:

cheers Graham

Offline NickG

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Re: Building the Division Master and modding my RT
« Reply #31 on: December 23, 2010, 08:48:22 AM »
John,

That must be really frustrating. You are doing really well to be back in there, everybody is glad to see you back in the shop but just take it easy.

As I've said before, I've got no excuses other than I am lazy. I can't even remember when I started those 'poppin' engines and still not finished, think it was fairly early this year though. I need to get back onto those next.

That will be a really useful bit of kit I'm sure as well as making life easier for you.

Nick
Location: County Durham (North East England)

Offline Brass_Machine

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Re: Building the Division Master and modding my RT
« Reply #32 on: December 30, 2010, 10:30:35 AM »
Topic split at John's request... find the Sterling power sources under "how do I"

Eric
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Offline madjackghengis

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Re: Building the Division Master and modding my RT
« Reply #33 on: December 31, 2010, 10:50:12 AM »
Hi Eric, that would be Stirling, as in Robert, not sterling as in flatware, not to quibble, but it might make a difference in search terms.   :poke:  mad jack

Offline Bogstandard

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Re: Building the Division Master and modding my RT
« Reply #34 on: January 04, 2011, 05:03:33 PM »
The project that I have been doing since the beginning of March is now done and dusted, and the chappie is over the moon with the results.
It looks like there are at least four patentable items that I have come up with during the build, so when those bits are sorted out legally, sometime later this year, I will do a bit of a post on it.

So now my time is my own, I will get this project back underway now that I can get back into the shop.

The first part covers modding my RT to put a pair of home made thrust washers into the worm drive system, If you don't want to do this stage, then there is no need to, but I want to remove as much backlash as possible, all in search of that elusive accuracy.


The table came apart in a matter of minutes, the first time it has ever been apart in over 20 years. There was a tiny bit of surface rust inside, but not on any mating surfaces, and the original grease was still on the wormwheel and worm. For a more detailed description about getting this type of RT apart, there is a link on the DM site.

http://medw.co.uk/wiki/index.php?page=6inch+Rotary+Table+Conversion+Guide

At the bottom of the above page, there is a link to a few more piccies.




The oilite bearing is the one I was waiting for over the Christmas period, and turned up a few days ago. The ID is 14mm and the OD 20mm, The length was of no importance other than I needed to be able to part a washer off either end.
The LH bit is the cam action to disengage the worm from the wheel and is also the support bearing for the worm shaft, and the RH item is the worm shaft itself




The first job to be done was to part just over 2mm from either end of the oilite bush, these will be my thrust washers.
Now a bit about oilite machining. USE NO LUBE OR COOLANT, it already contains oil and you don't want to contaminate it with anything else. The next bit is most important, DON'T LET IT OVERHEAT, otherwise the oil it contains will turn runny and drip out of the bearing, not what you want to happen. Just take it steady, pecking away and letting it cool, then peck a bit more. My cut, which would normally be over in a few seconds, took me about two minutes for each end.
With it being made of a sintered material, it can easily break if you misshandle it, so take care when deburring.




The two washers were then lapped on the cut face until they measured the same thickness all around the washer. I used 1200 W&D used dry (again no oil or water). One turned out at 2.10mm and the other 2.15MM, perfect for the job in hand. That job took about 10 minutes.




This is a bad shot, I couldn't control my shakes, but what it shows is removing 4mm (roughtly the thickness of the two washers added together) from the end that goes into the RT, closest to the worm. After machining this cast iron bearing (wobbling about all over the place because of the centre hole offset, the hole ran perfectly true) it was polished and chamfered on the end by hand while the chuck was turning.




The other end had the remaining 0.25mm taken off, purely because the turned face on the end looked like it had been done with a chisel. Again it was polished and chamfered.
So that was the sleeve done in a matter of minutes.




Now this pic shows a thing that always annoys me.
This is the other end of the shaft from the worm, and when the RT was originally assembled, and the backlash adjusted out by means of a round nut, they just stuffed a couple of steel grubscrews into the nut to hold it in place. This is the damage it caused, and it took me ages to actually get the nut off, even after removing the grub screws because the threads were so damaged. All it needed was a tiny slug of brass down in the hole before the grub screws, and the thread would have remained undamaged.
As it was, I had to resort to my thread file to get things somewhere back into shape, and get the original nut to screw back onto the thread, 14mm x 1mm pitch, a metric fine. The round nut won't actually be used during final assembly as I will be making a custom Oldham coupling to replace it, I am trying to keep things as short as possible.




So this is what it will look like on final assembly, except the new Oldham coupling will be fitted.



Someone is bound to notice that I should really have taken a couple of mm's from either end of the sleeve, but I didn't want to do that because it would have meant taking off the boss machined on the small end, which if ever the RT is returned to normal, the division set could not have been used. All it means is that the worm sits 2mm closer to sleeve, and it might even help a little by having an unused bit of worm acting on the wheel.

Bogs
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Offline Divided he ad

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Re: Building the Division Master and modding my RT
« Reply #35 on: January 04, 2011, 06:11:20 PM »
Nice! I don't think I'll be taking my RT apart any time soon??  But if I do I have a full guide right there since it's exactly the same :thumbup:


Now I'm gonna say it and this is before I hit the old Goggle button.... What's an oldham coupling?  (apart from a rotting pork joint  :lol: )


Now back to serious....  Oilite bearings. I knew they were sintered etc but did not know about their machining.  Do you ever need to re-impregnate them with oil? If so.... How? What with?    Well someone was probably going to ask? Thought it might as well be me   ::)   :)




Liking the return to the Tuit list  :thumbup:




Ralph.
I know what I know and need to know more!!!

Offline Bogstandard

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Re: Building the Division Master and modding my RT
« Reply #36 on: January 05, 2011, 12:55:35 AM »
Ralph,

Oldham coupling.

http://www.arceurotrade.co.uk/Catalogue/Stepper-Motors/Oldham-Couplings

I have never had to repack oilite bushes, so I wouldn't know. As far as I am concerned is that they are classed as lubricated for life. That is why I took it so steady when machining, I didn't want to lose or contaminate any of the precious contents.

Supposedly they can be repacked by boiling in an hard setting grease like Linklife, used on mo'sickle chains. But I have never done it. They are cheap enough to replace anyway.


John
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Location - Crewe, Cheshire

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Offline NickG

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Re: Building the Division Master and modding my RT
« Reply #37 on: January 05, 2011, 05:54:54 AM »
John,

Great work there, interesting post this, thanks. Shame about those threads - a bit of thought by the manufacturer and that could have been avoided.

On the subject of oilite bushes, where do you get the oilite material from? You may have said but does it come with an accurate bore? I have 2 jobs in mind for some.


Thanks

Nick
Location: County Durham (North East England)

Offline Bluechip

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Re: Building the Division Master and modding my RT
« Reply #38 on: January 05, 2011, 07:54:33 AM »
Nick

AFAIK you don't buy the material. They come ready made. Comme ca ..

http://www.bearingboys.co.uk/Oilite_Bearings-21-a

Just a supplier I used some years ago. There are others ..

Dave BC
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Offline NickG

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Re: Building the Division Master and modding my RT
« Reply #39 on: January 05, 2011, 10:00:10 AM »
Ah right, thanks Dave.

Nick
Location: County Durham (North East England)

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Re: Building the Division Master and modding my RT
« Reply #40 on: January 05, 2011, 10:57:56 AM »
Right John, got it  :thumbup:


All taken down and understood  :)


Thank you.


Never did get near goggle.... Was kind of late!  ::)





Ralph.
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Offline Bogstandard

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Re: Building the Division Master and modding my RT
« Reply #41 on: January 05, 2011, 11:24:58 AM »
Nick,

I got mine from the link Dave showed. I also buy their little boxes of engineering sundries like circlips, grommets etc. plus all sorts of little bits that one needs in the shop,

You don't nomally machine the bearings, as they come very accurately moulded ID & OD and also flanged to do the job in hand, it was just that, as far as I know, they don't produce washers like I required. So I just took the ends off a standard bearing which fitted my requirements perfectly.


John
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Location - Crewe, Cheshire

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Offline Bogstandard

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Re: Building the Division Master and modding my RT
« Reply #42 on: January 06, 2011, 04:08:09 PM »
The next little stage of the RT upgrade before I get to actually fitting the stepper.


Now ths is where I change my mind from my previous plan of making my own Oldham coupling end. For two reasons, I had made a balls up of my initial calculations which would mean I would be doing finger gymnastics trying to assemble the coupling and set up for no end float at the same time down the length of a fairly small diameter tube.
The other reason was that when I stripped down to the thrust washers this evening, the wear pattern on the faces was absolutely perfect, so rather than spoiling a good thing, I decided to go with what I had.
So I cut some soft brass slugs from a bit of 2mm rod, ground down a couple of grub screws to the right length. Then it was just a matter of a slug down the hole followed by a grub screw, this will stop damage to the threads, set up the zero end float and tighten things up. It turned out perfect, no detectable end float and the whole lot turned as smooth as the proverbial babies bum.




So that left me going the normal route people would take, just fitting an Oldham coupling to the 12mm handle spigot. My problem, 1" diameter coupling, fine, 10mm bore, not good.




So a spell on the lathe with a boring bar had it opened up to the right size.

I need to mention a little about couplings such as this, especially the ones with this type of clamp system. On no account try to drill them out to size, all the cross cuts will deflect the drill, and the hole could end up almost anywhere. By boring, that problem doesn't occur, and only takes a few minutes anyway. That is a warning that should be followed unless you want to end up with a wobbly coupling.




So everything was to my liking, and it was time to assemble everything into a RT. Just a reverse of the strip down procedure, and I assembled everything with bedway oil, which will also be used during it's machining life, that is why ball oilers are fitted and not grease nipples. But again two little things I did extra.

If you notice the main clamp screw on the casting top, I have knocked the tightening finger pin all the way thru to one side, this makes it much easier to do up/undo, but the screw must be in position before the main table is put on, otherwise you won't be able to screw it into the hole.
The other, is the clamp ring that is screwed onto the end. It has four locating bolts, but also four adjusting screws that are used to remove end play in the spindle assy to RT. A few minutes spent adjusting those and the locating bolts will get rid of all end play, but still allow smooth rotation of the worm spindle housing.




Just a little mechanical marking out/measuring exercise to find the PCD of the bolt holes in this flange. It will be used when the support tube is made.




So it is now at a stage where a few things need to be made.




Hopefully that will be sometime soon.


Bogs
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Offline Bogstandard

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Re: Building the Division Master and modding my RT
« Reply #43 on: January 07, 2011, 03:43:37 PM »
First things first, on the last post, I showed a bit of calculation written down on the undersheet. It said 16 PCD, in fact it should have read 16 PCR (pitch circle radius), so 32 PCD (pitch circle diameter).

I also need to apologise for little dribbly posts, I am doing my best in an attempt to get myself back into the shop, but at times I can't manage more than an hour or so, so you are seeing what I managed to achieve in that short space of time.

So now the next bit.

I am not completing the RT build up at this time, as it is easier for me to handle as it is.

I now needed to look at fitting the stepper motor to the RT. I am using one that I bought from Arc Euro, so the measurements I will be showing will be for that sized stepper.
First off, I mounted up the 6mm Oldham coupling (the other half of the one I fitted yesterday).

I am trying to keep the coupling tube as short as possible, so I marked up how much needed to be cut off the stepper shaft, a total of 10mm.




A couple of minutes with a hacksaw and his buddy, a file, and things looked just right.




Now I could get things into their correct positions and start to measure up.
The first thing was the OAL of the tube, everything else falls into place around that, and because the width of the stepper and the diameter of the flange on the RT is the same at 56mm, and because I don't have any 56mm square ali bar or larger available, I will be making a 2 part tube, loctited together when everything is lined up.




This is the sketch that I will be using. There are a couple of things that need pointing out.
The first one is that the four corner holes on the flange should read '4 off 5mm tapped holes', plus the data sheet that came with the stepper motor showing dimensions didn't quite match what I was holding in my hand, there was up to 1mm discrepancy in places, especially around the holes area, so I will be waiting until it is all assembled before spotting thru for the four corner holes.





Now there won't be any more posts on this until next week, as I am assisting Ralph over the weekend to 'fix' a couple of chucks.


Bogs
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Offline Divided he ad

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Re: Building the Division Master and modding my RT
« Reply #44 on: January 07, 2011, 07:41:53 PM »

Quote
Now there won't be any more posts on this until next week, as I am assisting Ralph over the weekend to 'fix' a couple of chucks.


Indeedy  :thumbup:  Apologies folks. Trying to get my machines sorted so that I can attempt to make something worth showing  :scratch:


I suppose I'd best take a camera now that it's public knowledge?




I'll report back in a different thread on that one  :headbang:



Looks like you're getting close on this too John. Sorry for the stoppage.






Ralph.
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Offline Bogstandard

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Re: Building the Division Master and modding my RT
« Reply #45 on: January 07, 2011, 09:20:15 PM »
No worries Ralph, anything to help a friend in need.


John
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Offline HS93

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Re: Building the Division Master and modding my RT
« Reply #46 on: January 07, 2011, 09:36:15 PM »
How much do you pay Ralph to be your  friend   :lol: :lol:

Peter
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Offline Bogstandard

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Re: Building the Division Master and modding my RT
« Reply #47 on: January 08, 2011, 03:00:23 AM »
Mal always gets Ralph a lump of choccie(s) for when he visits, but if you notice Pete, it is all hidden when you scousers call :lol:


John
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Location - Crewe, Cheshire

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Offline HS93

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Re: Building the Division Master and modding my RT
« Reply #48 on: January 08, 2011, 05:19:55 AM »
Mal always gets Ralph a lump of choccie(s) for when he visits, but if you notice Pete, it is all hidden when you scousers call :lol:


John

we have a present waiting for you next time you come to liverpool.

       :ddb: Peter  :ddb:
I am usless at metalwork, Oh and cannot spell either . failure

Offline John Stevenson

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Re: Building the Division Master and modding my RT
« Reply #49 on: January 08, 2011, 05:52:55 AM »
No need to go to Liverpool John to collect it.
I'll drop one off next time I'm passing.
Front window OK ?

[ That'll teach you to hid the chockie ]

John S.
John Stevenson