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Gallery, Projects and General => Project Logs => Topic started by: NormanV on September 04, 2014, 01:48:41 PM

Title: Making a Rotary Table
Post by: NormanV on September 04, 2014, 01:48:41 PM
 I have started on my Rotary Table. Here is the worm and wheel that I shall be using. It is a single start worm and the wheel has 30 teeth. This will give me 12 degrees for each turn of the worm.
Title: Re: Making a Rotary Table
Post by: NormanV on September 04, 2014, 01:50:19 PM
Here are the drawings showing the main details of what I plan to do. The main body is 160 x x150 x 50mm.
Title: Re: Making a Rotary Table
Post by: NormanV on September 04, 2014, 01:52:42 PM
I will be making the main body of the table as aluminium castings. These are the patterns. Although the main body of the table will end up open topped I made the pattern with a thin plywood top to make the moulding easier.
Title: Re: Making a Rotary Table
Post by: NormanV on September 04, 2014, 02:05:10 PM
I've had two days of problems trying to produce the two simple castings. On my first attempt the flask opened and the molten metal leaked out all over the ground. The main casting was ruined but the flat top plate was OK.
This is the second time that this has happened with this flask, I am guessing that it is too light, it will become firewood.
I started to remelt the faulty casting casting and ran out of gas! I haven't got any transport at the moment so am unable to go to get any more so I decided to use charcoal.
I started today with the charcoal and could just not get enough heat, if I had the air blast too high I was showering the surrounding area with cinders and on a low setting the charcoal was burning too slowly. It was rubbishy charcoal, tiny pieces and lots of dust. After 3 hours the metal melted and I was able to pour the casting. It did not turn out perfectly but it is usable. The metal cooled and did not fill the top where I had used the thin ply. I had expected this and planned to cut it away anyway. There are also two quite large shrink cavities in the top but they are of no consequence as I have left quite a large machining allowance.
Title: Re: Making a Rotary Table
Post by: vtsteam on September 04, 2014, 07:54:21 PM
You're forging ahead Norman! :thumbup: :thumbup: :clap:

I like your pattens with very heavy sections. Nice and solid.

3 hours to melt!!! That's painful. Must be very different to the charcoal briquettes we get here. Generally takes about 20-30 minutes from a cold furnace to melt 5 pounds of aluminum.

If I use the charcoal I make from wood (real charcoal) it does shower if the blast is too high, as you say, and it burns up faster, being less much dense. But the furnace temp can go much hotter than the commercial BBQ briquettes will take it. It will actually melt a steel rebar, and certainly melt bronze or brass. The downside is you have to add it a few times during an aluminum melt. Briquettes will usually complete an aluminum melt without any additional fuel top-up  for me. They are really different fuels.

Anyway, I'm glad you finally got your parts cast -- that was a Herculean effort in a 3 hour melt -- and a second one, as well. Great work!  :clap: :clap: :beer:
Title: Re: Making a Rotary Table
Post by: NormanV on September 05, 2014, 02:37:25 PM
Thanks Steve, I won't be going back to charcoal unless there is no other choice.
I've started machining the main casting, I did the top and bottom surfaces with the casting held in the 4 jaw chuck in the lathe, I was delighted with the finish that I achieved. There were no bubbles or inclusions in the metal.
I've also done two of the sides on my milling machine, I was a little nervous of holding such a tall casting in the vice but I needn't have worried, it held very securely. Tomorrow I will do the other two sides.
Title: Re: Making a Rotary Table
Post by: vtsteam on September 05, 2014, 03:43:46 PM
Nice having a mill to do that with!  :thumbup:  :beer:
Title: Re: Making a Rotary Table
Post by: mattinker on September 05, 2014, 03:53:54 PM
Thanks NormanV,

I'm enjoying this!

Regards, Matthew
Title: Re: Making a Rotary Table
Post by: philf on September 05, 2014, 04:01:59 PM
Norman,

Super work.  :thumbup:

What's next after you finish the rotary table?

 :beer:

Phil.
Title: Re: Making a Rotary Table
Post by: PekkaNF on September 05, 2014, 04:18:05 PM
Am I missing something here, I would imagine that you need a tail for this, or a second bearing, or is the table surface also a bearing surface to the rotab table? I'm not trying to be a pain, just curious.

Pekka
Title: Re: Making a Rotary Table
Post by: NormanV on September 05, 2014, 04:55:12 PM
Pekka, you may well be right, I do not mind the criticism. I had planned for the table to sit on the top plate and to be clamped to it. This would be fine for indexing but not for cutting curved parts. I could add a bridge piece with a bearing below the worm wheel, this would brace it. Any comments or ideas are welcome, I am no expert.
Title: Re: Making a Rotary Table
Post by: Arbalist on September 05, 2014, 06:17:04 PM
That's a nice chunky looking casting Norman, looking forward to seeing how you progress!
Title: Re: Making a Rotary Table
Post by: PekkaNF on September 06, 2014, 03:32:19 AM
I have normal #6 size rotab and it's fine with drilling and even light milling, but it is not happy when I  feed work against the mill, if it is even close to circumfrence of the rotab table. It looks like that the table is lifting or moving sideways.

If you only use the table for indexing, you may consider dimenssioning parts such way, that the bearing keeps everything in close contact and then you use clamps or dogs to pull the top (rotab table) into the body. If you can imobolize them for a cut, I believe it all would be fine for drilling and such.

The problem with bearings is that they are all designed to very spesific purposes and need some getting used to. Here you have short bearing distance and you need some rigidy in all directions. It would be simple if major forces would work only one or two directions.

Professional rotabs have very elaborate bearing arragements, simplest form is something like this on top:
http://www.wd-bearing.com/en/WD-YRT-Rotary-Table-Bearings/WD-YRT-Rotary-Table-Bearings.htm#.VAq2hmMsHOg

We hoppyist find it very difficuts to machine parts to make use of this kind of stuff and must hope that robot joint falls on front yard from e-bay or just make it the way it has been made in last 100 years - plain bearings:
http://www.deansphotographica.com/machining/projects/mill/rotary/50.jpg

The bottom bearing (surface) just pulls it all together. This does not look very different from yours:
http://www.deansphotographica.com/machining/projects/mill/rotary/rotary3.html

Maybe you'll find it useful.

Pekka
* fixed mass of typos, I wonder if anybody made any use of this. I got new mini laptop and keyboard is very different from the old one. Aso, I'm blind as a bat and this display is small. I allready got time on optometris. I need separate glasses for driving, work, reading and soon for a computer display. What next? A guide dog or white cane?
Title: Re: Making a Rotary Table
Post by: NormanV on September 06, 2014, 11:03:15 AM
Thank you Pekka for your detailed comments, the Taig design is similar to what I intend to do including clamping the table to the body whilst making a cut. This of course does not enable me to make a cut whilst rotating the table. This is something that I had not given enough thought to as it is a facility that would be useful. There may be enough space under the worm wheel to fit a bearing that would give the support needed, but I do have a piece of equipment that may contain a ring bearing that would support the table. I'll only know this if I can work out how to dismantle it!
Today I machined the remaining sides of the body casting and faced off the top plate. I am really pleased with these two castings as they have no bubbles or inclusions where it matters. I am confused at the talk of the need to degass the molten metal, I do nothing other than skim the top of the melt before I do the pour. Forty years ago I did some aluminium casting at evening school and that metal was degassed but still had bubbles in it.
The milling machine does throw the swarf around all over the place, I had to spend a lot of time vacuuming it all up as I found it quite irritating crunching underfoot.
Title: Re: Making a Rotary Table
Post by: NormanV on September 06, 2014, 11:06:46 AM
By the way, does anybody have any suggestions as to the cause of the rings on the top plate? The feed was done by hand but the rings are equally spaced.
Title: Re: Making a Rotary Table
Post by: vtsteam on September 06, 2014, 09:36:33 PM
Norman, I'm with you on not de-gassing (or fluxing) aluminum melts. I never have, but the aluminum stock I used was clean and always from castings rather than mixed extrusion scrap. I poured relatively cool, unless very thin castings were required, there was minimal dross, and the charcoal protected the top of the melt. It poured nicely, and it looks like yours does, too.

I don't think the circles are perfectly evenly spaced so I'll take a guess at what they are -- pickup of a small aluminum welded chip on the lathe tool tip, and it gradually wearing off, then picking up a new one.


Title: Re: Making a Rotary Table
Post by: awemawson on September 07, 2014, 04:26:28 AM
Norman, consider a thin sheet of Teflon as a bearing if space is tight. The large surface area gives loads of load capacity, and as it will always be a slowish rotation there is no issue with speed and heat.
Title: Re: Making a Rotary Table
Post by: NormanV on September 07, 2014, 06:02:56 AM
Teflon would certainly be less bulky than a bearing. I managed to dismantle the piece of equipment that I have with the ring bearing. Here is a photo, the balls run on hardened steel. Would this be Ok to take the cutting forces? The balls are approximately 4mm dia. Rather than try to clamp the table down onto the top of the body I could use a split cotter on the spindle. Any comments?
Title: Re: Making a Rotary Table
Post by: awemawson on September 07, 2014, 07:26:11 AM
Does the Admiralty know that you have that gun mounting  :lol:
Title: Re: Making a Rotary Table
Post by: vtsteam on September 07, 2014, 09:51:36 AM
I think it was just a really serious Lazy Susan  :lol:
Title: Re: Making a Rotary Table
Post by: BillTodd on September 07, 2014, 10:37:00 AM
With a slow moving thing like a rotary table, a plain bearing will give the better damping, making less prone to ringing.

Bill
Title: Re: Making a Rotary Table
Post by: NormanV on September 07, 2014, 01:07:55 PM
Bearing (!) in mind Andrew's and Bill's comments here is my revised design. I like the idea of using Teflon as a bearing surface and have exchanged the bearing with a bush, ideally this would be bronze but as I don't have any I will use steel. This should not cause problems when making a cut and hopefully I will be able to rotate the table to produce curved surfaces.
Title: Re: Making a Rotary Table
Post by: PekkaNF on September 07, 2014, 02:18:33 PM
Is that from gunsight or "target finder"? I like that a lot.

I don't like PTFE that much. I have used it a little on fly reel bearing/brake, but it was not that easy to glue. Also it needs certain surface quality, too coarse is no good, but neither is too smooth. It is also very soft and has tendency to extrude when loaded. Therefore you need a LOT of area. You might get away on top, because you have a lot of surface area there, but I don't like the look of bottom bearing on teflon. I would use metal (or composite) plain bearing. Easy on lubricant, you don't want it on teflon. The good thing is that if teflon sucks, you can go on POM and after that you can go reinfoced composites, and by them you know a thing or two on syntethic bearings.

As you see I'm big on rolling bearings, but plain bearings are great on loads which would brinnel ballbearings in no time.

My 2 erocents,
Pekka
Title: Re: Making a Rotary Table
Post by: NormanV on September 07, 2014, 02:38:01 PM
I have no idea what the original use of the bearing was, I removed it from a piece of specially made equipment whose use I do not know.
Title: Re: Making a Rotary Table
Post by: mattinker on September 07, 2014, 03:12:17 PM
You could use mild steel as a thrust washer against Al, Al steel are a good bearing combination. Example, steel camshaft running in Al cylinder heads. For the speed that your dividing head is going to turn, oil lubricated Al steel would be  good.

I liked the idea of a split cotter to lock the turntable.

Regards, Matthew.
Title: Re: Making a Rotary Table
Post by: Fergus OMore on September 07, 2014, 03:21:29 PM
Agreed Matt. Frankly, I have a number of rotary tables- some professionally made and others home made from assorted metals. Only one has ball races and that is on a Clarkson tool and cutter grinder.

It suggests that this idea of needing fancy bearings in model making somewhat 'over engineered'

Regards

Norman
Title: Re: Making a Rotary Table
Post by: awemawson on September 07, 2014, 03:26:33 PM
If you recall the pictures of when I was rebuilding that Nikken rotary table unit as a 4th axis for my CNC mill it has rollers for table down force and rollers for side thrust:

http://madmodder.net/index.php/topic,9439.0.html

I suspect though it was built to withstand far higher forces than you will generate with your splendid beast
Title: Re: Making a Rotary Table
Post by: NormanV on September 07, 2014, 03:34:19 PM
Yes, I realise now that a PTFE washer in the lower position would be daft, I will use a steel one. I like the idea of using PTFE under the table, I checked on Wikipedia and it gives a yield strength equivalent to 3,300 PSI. It seems unlikely that my usage will get near to that.
Andrew, I think that your rotary table is probably a bit big for my milling machine! I think that I was trying to overengineer it, for my light usage I think plain bushes and washers will do the job.
Title: Re: Making a Rotary Table
Post by: NormanV on September 08, 2014, 08:11:48 AM
I have bored the holes for press fitting the bushes for the worm. I had originally planned to bore it by mounting on the tee slotted table on my lathe and boring it with a boring bar between centres. Unfortunately I had nothing to use as packing to raise it to centre height, so instead I mounted it in the four jaw chuck. I was concerned that it would be a bit precarious but I had no problems. When boring the hole nearest to the chuck the boring bar flexed rather alarmingly but by taking light cuts and several at the same setting it turned out well.
Title: Re: Making a Rotary Table
Post by: NormanV on September 08, 2014, 08:13:50 AM
I also made the bushes to mount the worm, when pressed in the worm rotates freely and without any play.
Title: Re: Making a Rotary Table
Post by: vtsteam on September 08, 2014, 08:19:58 AM
Coming along nicely, Norman! :clap:
Title: Re: Making a Rotary Table
Post by: mattinker on September 08, 2014, 01:00:43 PM
I'm really enjoy your threads!

Regards, Matthew
Title: Re: Making a Rotary Table
Post by: NormanV on September 08, 2014, 06:04:45 PM
Thank you Steve and Matthew. Tomorrow I'll be working on the main spindle. Trouble is I don't have a piece of steel the right size so I will have to try to work out another solution.
Title: Re: Making a Rotary Table
Post by: NormanV on September 09, 2014, 10:49:53 AM
The main spindle is done. I just made it from two pieces of steel bolted together. I may cut a keyway to engage with the worm wheel but it is quite a snug fit and may not be necessary.
Title: Re: Making a Rotary Table
Post by: NormanV on September 10, 2014, 02:27:56 PM
I cast the table today, despite my misgivings I used charcoal again. This time it was much more successful, it only took an hour to complete the melt and used half as much charcoal. I had a stronger air blast and that seemed to do the trick.
I've also machined it all over and it is now mounted on the spindle.
Title: Re: Making a Rotary Table
Post by: Arbalist on September 10, 2014, 04:01:36 PM
Looking good again Norman. As an aside, I've noticed in some of your builds you use pozidrive countersunk screws quite a bit, may I suggest you seek out some Torx versions next time you need to stock up on fasteners as the drivers don't cam out like they can on cross point screws.
Title: Re: Making a Rotary Table
Post by: Manxmodder on September 11, 2014, 07:39:36 AM
Good work Norman,coming along nicely.

I would second Arbalist's suggestion on Torx head screws as they really are a far better engineered screw driving head than any of the cross head variety.......OZ.
Title: Re: Making a Rotary Table
Post by: NormanV on September 11, 2014, 08:34:23 AM
I agree with both of you that pozidrive are not particularly good. I am not familiar with Torx but my first choice would be Allen socket head screws. Unfortunately pozidrive is what I have and that is what I will use until they are finished.
Title: Re: Making a Rotary Table
Post by: Arbalist on September 11, 2014, 11:26:47 AM
I try to avoid socket hex countersunk screws in the small sizes as I've had the sockets round off. This has required me to drill out a few fasteners. I believe the problem is that sometimes countersink screws can self tighten with vibration as I certainly haven't over tightened them.

Just one random supplier of Torx screws:

http://www.accuscrews.co.uk/32-hexalobular-countersunk-screws
Title: Re: Making a Rotary Table
Post by: philf on September 11, 2014, 12:22:22 PM
I try to avoid socket hex countersunk screws in the small sizes as I've had the sockets round off.

Arbalist,

I second that. When I built a vertical head for my Aciera many years ago I did a trial assembly of a bearing retainer/seal housing with M6 countersunk socket screws. Two minutes later I couldn't get them out with the correct 4mm Allen key which ended up rounding off. I resorted to drilling the heads off. I used slotted screws in the end. The same can apply to button headed socket screws which have smaller sockets than a normal cap head screw.

Phil.
Title: Re: Making a Rotary Table
Post by: NormanV on September 12, 2014, 03:12:40 PM
It's not been a good day today. I bored the top plate to take a steel bush for the spindle to run in. I then started on the bush, I managed to make the OD undersize and the ID oversize! So I started again, I was lucky to find that I had a piece of steel just a few thou oversize, but I am fed up with having to hacksaw through 40mm dia. bar (next project, power hacksaw)
I completed the bush correctly this time, a press fit into the top plate and, at the moment, a tight fit on the shaft. Tomorrow I will lap it to fit.

Title: Re: Making a Rotary Table
Post by: NormanV on September 13, 2014, 06:04:01 AM
I finished lapping the bush and pressed it into the top plate and then drilled and tapped the holes for attaching the top to the main body.
Title: Re: Making a Rotary Table
Post by: NormanV on September 13, 2014, 06:07:28 AM
I have used a PTFE washer under the table to reduce friction. I scored the outside circle with my dividers and then snapped the waste material off. It gave a rather ragged edge so I tried cutting it with a scalpel, it cut very easily and gave a much better edge. I had to resort to sanding the outer edge to smooth it.
Title: Re: Making a Rotary Table
Post by: NormanV on September 13, 2014, 06:11:38 AM
Then the exciting part! First assembly, it all fitted together nicely. You will notice that I have left the top oversize. This was to enable me to adjust the gears to be free of backlash without the necessity of ultra precision marking out and cutting, this has worked well. The next job is to dismantle it and trim the ends.
Title: Re: Making a Rotary Table
Post by: awemawson on September 13, 2014, 06:50:07 AM
 :thumbup: All looking very nice Norman  :thumbup:

Are you going to mill Tee slots or drill and tap a matrix of holes as hold downs?
Title: Re: Making a Rotary Table
Post by: NormanV on September 13, 2014, 07:07:24 AM
I would like to machine tee slots but am a bit nervous of it. I might try first on a piece of scrap. Drilled and tapped holes would be easier plus I wouldn't need to buy or make a cutter.
Title: Re: Making a Rotary Table
Post by: awemawson on September 13, 2014, 08:04:27 AM
If you place tapped holes where you would have put Tee slots, then you have the option of still making the slots at a later date  :ddb:
Title: Re: Making a Rotary Table
Post by: NormanV on September 13, 2014, 09:05:23 AM
Good idea Andrew!
The next job I attempted today was the locate the worm wheel on the shaft. Ideally I would cut a keyway in the shaft to match the one in the gear, I don't yet have the collet to fit the cutter required so I thought that if I put a short grubscrew in the shaft it would locate in the slot. This I did and the gear slipped on beautifully and was fixed in position on the shaft. Unfortunately it makes it impossible to assemble due to the curved face of the worm wheel!
Plan two is to drill a hole axially into the end, half in the shaft and half in the wheel and pin it, I've done it before to lock loco wheels onto their axle so I know it will work.
Plan three is to be patient and wait until I get the correct size collet!
Title: Re: Making a Rotary Table
Post by: awemawson on September 13, 2014, 09:41:46 AM
Norman,

make a temporary collet on your lathe. Chuck up a bar of a size that you do have a collet for, drill suitably for the cutter, fix with a grub screw. Take light cuts. OK it won't be as accurate as a collet, but should suit the job in hand, especially if your cutter is narrower than the slot and you are cutting in two passes, one each side.

Alternately you could 'shape' the key way in the lathe using a parting tool held sideways, or with a bit of hss suitably ground. Youtube abounds with examples :)
Title: Re: Making a Rotary Table
Post by: NormanV on September 13, 2014, 03:00:55 PM
Andrew, you make me feel a bit foolish, I seem to be looking for the problems that don't exist. I did exactly what you suggested and made a holder for the cutter to fit in a larger collet. The whole thing took about 30 minutes and I ended up with a proper bit of engineering. Thanks.
Title: Re: Making a Rotary Table
Post by: awemawson on September 13, 2014, 03:09:23 PM
Very happy to help and equally glad that it worked out ok for you  :thumbup:

...advice based on decades of having to make do and mend   :ddb:
Title: Re: Making a Rotary Table
Post by: dsquire on September 13, 2014, 04:55:48 PM
Norman

Glad to see that it is all coming together 1 piece at a time. I sometimes think that making tools to make tools is more fun and relaxing than making widgets. Keep up the good work. I may bot be saying much but I am watching from the background.   :D :D

Cheers  :beer:

Don

Title: Re: Making a Rotary Table
Post by: NormanV on September 14, 2014, 05:23:05 AM
Whilst I had the 5mm cutter in the milling machine I thought that I would machine the slots for clamping the table in position when in use in a horizontal position. I've also drilled holes for clamping it vertically.
Title: Re: Making a Rotary Table
Post by: Manxmodder on September 14, 2014, 08:23:18 AM
Norman

Glad to see that it is all coming together 1 piece at a time. I sometimes think that making tools to make tools is more fun and relaxing than making widgets. Keep up the good work. I may bot be saying much but I am watching from the background.   :D :D

Cheers  :beer:

Don

Agree with you Don,and the added bonus being the more tools one endeavors to make the more experienced and competent one gets as a tool maker :thumbup:.......OZ.
Title: Re: Making a Rotary Table
Post by: NormanV on September 17, 2014, 09:40:51 AM
The next part needed some thinking, I have never handled a dividing head or rotary table and was not quite sure how you use the division plates and sector arms. I had a read of Dave Gingery's book on the dividing head and managed to work it out.
Yesterday I made the pattern for the support for the handle and mount for the plates and arms. Most of my patterns are made from MDF, which is horrible stuff when you have a lot of shaping and sanding, but this one I made from mahogany. It was lovely stuff to work with. Also up to now I have used two part car body filler for the fillets. This does a good job but is a lot of work sanding to remove the lumps and bumps. This time I used a water based wood filler, it was much easier to apply as it has a longer setting time. After about twenty minutes I wetted my finger and smoothed it down leaving hardly any sanding to do. The only disadvantage to using it is the two hour setting time but it is worth it due to the convenience of use.
Title: Re: Making a Rotary Table
Post by: NormanV on September 17, 2014, 09:48:33 AM
I made the casting today, I was melting a lot less aluminium due to the small size of the casting and I had it liquid in 30 minutes.
I machined it this afternoon and was disappointed to find a sand inclusion but it does not affect the function and will not show when it is all assembled.
The end of the shaft of the worm has a dog (I think that is what you would call it) so I had to mill a piece of steel to fit. Certainly a lot pleasanter task than trying to file it!
The top face of the casting is going to be marked with twelve divisions which will give me one degree markings that I can use until I get the division plates made.
Title: Re: Making a Rotary Table
Post by: NormanV on September 18, 2014, 05:06:10 AM
It is now assembled, albeit with a temporary handle. It is quite stiff to turn even with the PTFE under the table, at least there is no loose play!
Title: Re: Making a Rotary Table
Post by: DavidA on September 18, 2014, 05:44:37 AM
Not bad,  Norman.  Not bad at all.

Dave.
Title: Re: Making a Rotary Table
Post by: awemawson on September 18, 2014, 06:29:01 AM
 :thumbup: in fact pretty d@@n good  :thumbup:
Title: Re: Making a Rotary Table
Post by: NormanV on September 20, 2014, 07:44:18 AM
Thanks, Andrew and David.
Today I made and fitted the table clamps, I did not proceed with the split collet that I mentioned earlier as it is a bit tight for space. Also I liked the fact that the table is pressed firmly down onto the top plate when using clamps.
I drilled a matrix of tapped holes in the table top as suggested by Andrew, I may machine tee slots at a later date, I'll see how I get on with the tapped holes.
I'm surprised at the weight, even though it is mostly aluminium it feels quite substantial.
Title: Re: Making a Rotary Table
Post by: krv3000 on September 20, 2014, 04:38:24 PM
hi bin keepin an i on this brill work  :)
Title: Re: Making a Rotary Table
Post by: Manxmodder on September 20, 2014, 09:16:53 PM
Great result, Norman. Looks like it will be really sturdy in use......OZ.
Title: Re: Making a Rotary Table
Post by: NormanV on September 21, 2014, 09:55:06 AM
Thanks for the comments, it keeps me keen.
Today I made the sector arms, fiddly bits to do as I wanted to keep the size down. I attached the fixed arm quite crudely by peening over the metal with a centre punch. Ideally I would have used something like 10BA countersunk screws but as I have neither screws nor tap I did it this way.
I'm going to make the division plates from cast aluminium, I am not expecting to be using it that often so they should last. If not I can always make steel ones later.
Title: Re: Making a Rotary Table
Post by: Meldonmech on September 21, 2014, 10:04:51 AM

       Hi Norman I agree with you regarding the water based wood filler for pattern making. I have been converted for three years now, and find it much easier to use and much cheaper.  The RT looks great, well done.

                                                                Cheers  David
Title: Re: Making a Rotary Table
Post by: NormanV on September 26, 2014, 02:17:10 PM
 It's been an interesting couple of days. Yesterday I made a pattern for the division plates and cast them. I also dug out an old pattern to make a casting to use as a jig to hold the plates for machining.
Title: Re: Making a Rotary Table
Post by: NormanV on September 26, 2014, 02:20:40 PM
I made a drilling jig out of a piece of scrap steel to ensure that the jig, the plates and the mounting boss on the rotary table all agree.
Title: Re: Making a Rotary Table
Post by: NormanV on September 26, 2014, 02:23:18 PM
I turned the two plates to thickness, bored them and then drilled for the mounting screw. I only drilled one hole as I thought that would be sufficient but have now decided to drill the second hole to ensure the plate mounts square.
Title: Re: Making a Rotary Table
Post by: NormanV on September 26, 2014, 02:31:20 PM
I then machined the casting for the jig, it was a terrible casting with a large shrink cavity but it was good enough for the jig. All I had to do to it was turn both sides and bore it for a stepped locating pin to go through the centre.
The pin had three steps 16mm to fit the hole in the centre of the rotary table, 20mm to fit the hole through the jig and 24mm which is the hole size in the centre of the plates. I made the pin a press fit in the casting, I had a bit of trouble pressing it in due to the shrink cavity in the casting, it picked up an edge and pushed the pin off centre. I had to knock it out and file the offending part, it then pressed in fine. I used the template to drill the mounting holes for the plates and was pleased to find that the plate will fit on using either screw hole in the jig.
Title: Re: Making a Rotary Table
Post by: NormanV on September 26, 2014, 02:38:04 PM
I then mounted the jig in the four jaw chuck, fitted the plates in turn and turned the outside diameter.
Tomorrow I will mount the jig on the rotary table and set it up for drilling the rings of holes.

As a bynote: I have read in some forums people stating that they only ever use their three jaw chuck. I seem to have to swap from 3 jaw to 4 jaw, and change the jaws from inside to outside on a daily basis. Is this unusual?
Title: Re: Making a Rotary Table
Post by: mattinker on September 26, 2014, 03:38:55 PM
Usually, when I need the four jaw chuck the three jaw is mounted and the jaws in the four jaw are the wrong way round! People who only use the three jaw work exclusively on round things!

I'm still enjoying this thread!

Regards, Matthew
Title: Re: Making a Rotary Table
Post by: awemawson on September 26, 2014, 05:55:14 PM
My three jaw is remarkably accurate over a very wide range, so very often I can get away with just using it as is, but when things need to be 'nuts on' then obviously the four jaw is needed.

Often of course if you plan your work to tun all diameters at one 'gripping' they will be concentric even if the three jaw is all over the place.
Title: Re: Making a Rotary Table
Post by: Meldonmech on September 27, 2014, 04:55:42 AM
 .
    Norman I like yourself was always changing chucks and jaws. When I was offered a larger 5 inch lathe at a price I could not refuse, I then had two lathes. I now normally keep a three jaw on the smaller 3.1/4 inch lathe and a four jaw on the 5 inch lathe.
        The arrangement  works very well, and saves a lot of laborious time.

                                                                      Cheers vDavid
Title: Re: Making a Rotary Table
Post by: NormanV on September 27, 2014, 05:39:46 AM
I've got two lathes, both with the same chuck mount and six chucks/faceplates. One of the lathes is very noisy and I can't bear using it too often. I need to stop making things for a while and fix the lathe!
Title: Re: Making a Rotary Table
Post by: NormanV on September 27, 2014, 08:44:06 AM
I've started on the division plates. Firstly I cut a strip of paper to the circumference of the disc and then divided it into the required number of spaces. I then taped the strip of paper around the edge of the disc mounted it on the rotary table with a temporary index marker and drilled the holes with a centre drill. It is a very tedious operation but at least I have completed the circle with the largest number of holes (48) and also the next smaller.
Title: Re: Making a Rotary Table
Post by: awemawson on September 27, 2014, 10:16:34 AM
Cunning use of slanted lines there Norman  :bow:

Makes me appreciate my CNC milling machine - draw it out and watch it made  :ddb:
Title: Re: Making a Rotary Table
Post by: NormanV on September 28, 2014, 08:42:08 AM
Just goes to show that it is worthwhile paying attention at school!
If you want precision soulless parts CNC is good, but my way produces parts with an individual character of their own! i.e. not high precision but adequate.
Today I drilled some more holes, that's enough for now. I think that will give me all the divisions that I am likely to need but there is space on both discs to add more plus I will cast a couple more for any future special needs.
Title: Re: Making a Rotary Table
Post by: PekkaNF on September 28, 2014, 02:05:56 PM
Those looks very good to me.

How do you know how many holes certain circle has?

Pekka
Title: Re: Making a Rotary Table
Post by: NormanV on September 28, 2014, 03:42:23 PM
I shall stamp the numbers on the back, at the moment they are written in pencil.
Title: Re: Making a Rotary Table
Post by: PekkaNF on September 29, 2014, 03:34:30 AM
Jup. Stamped numbers are way to go. And over head projector (spirit soluble) pen is good to mark the holes you need. Just to doblecheck. If those arms are lose it's really easy to knock one over or something and results can be humorous.

Pekka
Title: Re: Making a Rotary Table
Post by: NormanV on September 29, 2014, 02:15:38 PM
It's finished! Today I made the retracting pin that locates in the holes and that just about winds it up.
Now I shall have to start investigating gear tooth cutters, I think that it will be fun to have a go at making some gears.
Title: Re: Making a Rotary Table
Post by: awemawson on September 29, 2014, 02:29:55 PM
 :clap: :clap: Well done that man  :clap: :clap:

It's come out really well, and it's been quite a journey  :bow:
Title: Re: Making a Rotary Table
Post by: NormanV on September 29, 2014, 02:32:34 PM
Thank you Andrew. It is great to be able to see projects right through to the end. Retirement is a wonderful thing!
Title: Re: Making a Rotary Table
Post by: awemawson on September 29, 2014, 02:35:33 PM
Thank you Andrew. It is great to be able to see projects right through to the end. Retirement is a wonderful thing!

Oh yes I can empathise with that sentiment. I still have quite a bit to do around the farm, but really my time is my own these days and I guard it jealously
Title: Re: Making a Rotary Table
Post by: philf on September 29, 2014, 02:58:38 PM
It's finished! Today I made the retracting pin that locates in the holes and that just about winds it up.
Now I shall have to start investigating gear tooth cutters, I think that it will be fun to have a go at making some gears.

Norman,

First you need to make a Eureka relieving attachment then!  :lol:

 (I don't think it would work in aluminium unfortunately!) :(

See: http://madmodder.net/index.php/topic,7956.0.html

Phil.
Title: Re: Making a Rotary Table
Post by: Arbalist on September 30, 2014, 10:57:36 AM
After watching all your casting escapades Norman I wish you lived up the road from me, It could have helped me solve my mill riser quandary! Melting down an old step ladder makes more sense than taking it down the dump ...  :D
Title: Re: Making a Rotary Table
Post by: nel2lar on October 02, 2014, 12:09:36 AM
Norman
Nothing less than brilliant, loved the casting and all that machining. Now you have a dividing head that is ready for the next project. And you are not set back the big bucks, from cast to finish. Georgious
Nelson Collar
Title: Re: Making a Rotary Table
Post by: NormanV on October 07, 2014, 03:38:17 PM
Thanks Nelson.
I actually have a use for my Rotary Table, I would like to make some gears for a project that I started last year. I had considered using a chain drive but the original had gears and now that I have the RT I might just as well have a go at gears. Before I can do them I will need a tailstock. Here is a sketch of what I am thinking of making. I am planning to use three castings as that will make it easier to machine. The centre height will be adjustable to match the RT when it is stood on end.
Title: Re: Making a Rotary Table
Post by: nel2lar on October 08, 2014, 10:31:20 PM
Norman
There is no limit to what can be made. Aluminum is a soft metal but for what we do it is more than do-able. Very nice RT and now we are looking for the tail stock. Just love to see the parts evolving from wood to metal and then finish and assembled. There is no stopping.
Looking Good
Nelson Collar
Title: Re: Making a Rotary Table
Post by: vtsteam on November 29, 2014, 09:10:34 PM
Great project Norman!!   :clap: :clap:

(just catching up)
Title: Re: Making a Rotary Table
Post by: NormanV on November 30, 2014, 04:24:05 AM
Thanks Steve. Welcome back, where have you been?
Title: Re: Making a Rotary Table
Post by: vtsteam on November 30, 2014, 10:43:41 AM
Norman, looking forward to reading about your upcoming projects.

I've just been trying to get ready for winter here -- cut 10 cords of wood, mixed and poured concrete in a shed and open roofed section near the house, but mainly caught up in volunteer local School Board Director duties -- dealing with district educational financial problems. That's been very wearing, and after 20 months of trying to bring some financial and educational sense to people have decided to resign by January 1. That will allow me more time to do fun mechanical stuff here, plus I'll be able to sleep at night instead of being too frustrated to. I need to focus on more positive things, and communicate with like minded-people. I still volunteer to teach science in our elementary school once a month -- that part is fun!
Title: Re: Making a Rotary Table
Post by: krv3000 on November 30, 2014, 07:09:54 PM
in a word brill i have the makings ie the worm and gear just need a mill
Title: Re: Making a Rotary Table
Post by: NormanV on December 16, 2014, 01:38:26 PM
Two months after saying that I was planning to mke a tailstock for the rotary table I have got around to casting the parts. I am out of practice, first attempt the sand fell out when I inverted the flask. I packed it in tighter for the second attempt and it stayed in.
Not a great casting but it will clean up OK.
Title: Re: Making a Rotary Table
Post by: vtsteam on December 16, 2014, 03:20:51 PM
And you've got the mill to do it with, too!  :thumbup:
Title: Re: Making a Rotary Table
Post by: NormanV on December 16, 2014, 04:17:29 PM
Exactly!

But quite often it is easier and quicker to hold it in the 4 jaw on the lathe.
Title: Re: Making a Rotary Table
Post by: vtsteam on December 16, 2014, 05:54:20 PM
Agreed. It's the Gingery influence.  :)
Title: Re: Making a Rotary Table
Post by: NormanV on December 25, 2014, 10:36:24 AM
Did the basic machining on the castings for the tailstock today.
Title: Re: Making a Rotary Table
Post by: NormanV on January 15, 2015, 10:23:03 AM
The tailstock is more or less finished, all I need to do is to knurl the knob (or other gripping system) and make a lever to replace the clamping nut. It is not a thing of beauty but it works. I milled a slot for a locating screw to prevent the centre ram from rotating and incorporated a proper clamping device to lock the ram. I had intended having slots in the base for clamping screws but decided I would use loose clamps which would give me more latitude in positioning it.
The vertical slot in the centre is for a jacking screw to facilitate adjustment of the height.
Title: Re: Making a Rotary Table
Post by: NormanV on August 09, 2017, 06:26:49 AM
Two and a half years after completing this rotary table I have finally got a need for it but before using it. I decided to do away with the grid of holes in the top, that would fill with swarf the first time that I used it, and to cut tee slots. I have had the cutter for over a year but was worried about spoiling the table. I needn't have worried it was very straightforward to do and now I have it set up to cut the slots for the spokes in a rear wheel hub for a "Minnie" traction engine(cast aluminium of course!). First though I need to make the milling cutter for the slots as I do not have one of the correct size.