Author Topic: Rotary table  (Read 25516 times)

Offline madjackghengis

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Re: Rotary table
« Reply #25 on: May 17, 2010, 12:16:53 PM »
Hi Chuck, welcome and good luck.  I've got a 72 tooth rotary table and I'm quite pleased with it, but you don't have to buy an expensive gear to make one.  You can use the method of dropping verticals to set up a blank round piece for an index plate with seventy two holes, make a cutter for a flycutter, to cut the teeth, and make your own gear.  Take a piece of light card stock such as a shirt box, make a strip which precisely fits around the outside of your blank, the larger the easier and more accurate spacing, lay this strip down on a flat work table you can put pin pricks in without causing a war with the wife, take a yard stick or longer measuring device that is longer than the strip, figure out which marks you can count out seventy two of, and have the end of the yard stick on one end of the strip, and the seventy secondth mark vertically in line using a square, with the other end of the strip, with both the strip and the yard stick well attached to the work table, use a straight edge under the strip, a square setting on the straight edge, and move it to line up with the chosen mark on the yard stick which should be at an angle to the strip, and draw a line down perpendicular to the strip, ending up with seventy one lines, and the two ends connected together being the seventy second line.  This secured to the blank will allow you to index the blank, and drill indexing holes for positive stops to cut the teeth.  Choose a gear pitch that meets your size expectations before laying this all out, and then you can use the gear tooth profiles in any good gear book or machinery's handbook, and grind a bit to match what is shown, which will cut well if carefully done.  The blank its self can be drilled, a temporary angle plate jig set up, with a pin to match the hole circle, and the teeth cut on the blank.  If you set the angle plate at the pitch angle of the worm you intend to use, chosen to match the pitch of the gear, the worm can be perpendicular to the gear, otherwise it will have to be set up at that pitch angle, to get it to interface with the gear.  It is worth the trouble to get the worm perpendicular, usually.  I just used this method, essentially, to make a replacement gear of fifty one teeth for a machine which wore all the teeth off its worm gear.  You can use a large round piece of plywood for a temporary table for your drill press, and thus have the spacing of the dropped marks wider, and easier to make accurately, with the blank attached to the wood and drilled after you attach the strip to the plywood.  I'd be happy to answer any questions regarding this, although I believe there is at least one place in this website where this has been demonstrated.   :thumbup: mad jack

Offline Dean W

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Re: Rotary table
« Reply #26 on: May 17, 2010, 05:17:39 PM »

If your photos are in Photobucket, you don't have to do anything but copy and past.  You don't need to
use the IMG tags, as Pbucket puts them in automatically.  Check it out:


Thanks for the correction, Dean  :thumbup: . I was getting mixed up with inserting pics in posts to Yahoo groups.

Andy

Oh!  Andy, I didn't mean to be "correctional".  All these forums seem to use different software to decide how they want pictures.
It's confusing!

Regards,

Dean
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Offline andyf

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Re: Rotary table
« Reply #27 on: May 17, 2010, 06:46:49 PM »
Oh!  Andy, I didn't mean to be "correctional".  All these forums seem to use different software to decide how they want pictures.
It's confusing!

Regards,

Dean

No worries, Dean - my post was a bit misleading, and needed correcting - as you rightly pointed out, I was overcomplicating the process.

Chuck, it's time you tried out a pic or two!

Andy
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I've cut the end off it twice, but it's still too short

Offline Chuck in E. TN

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Re: Rotary table
« Reply #28 on: May 17, 2010, 06:56:56 PM »
O.K. Here's the pic's so far.
The Collected materials:



I got the origional 4" round split again:



This is the worm set I started with. Also shown are the axil for the rotating part and the bearings that will be used.



I cut a piece off the treadmill elevation screw, bored it to fit an axil that would also fit a skate bearing.
Worm on the axil:



The worm gear shown is an 80 tooth change gear from my lathe. I may go with a 60 tooth change gear, or develope a method of using either?
Photo bucket does make it easier when you figure it out!
« Last Edit: May 17, 2010, 07:07:42 PM by Chuck in E. TN »
Chuck in E. TN
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Offline Chuck in E. TN

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Re: Rotary table
« Reply #29 on: May 28, 2010, 07:43:31 AM »
I am having problems turning the copy of my lathe’s spindle nose. I’m getting heavy chatter, digging in and even stalling the lathe. I made a rookie mistake by not asking the machine shop I got the piece from, what material it was.
I have reground bits, honed and reground the HHS bits again. I have tightened all the cross slide and compound gibs. The cross slide and compound have been lapped.
I am currently turning it at 300-320 rpm, and chips are short, curly, hot and blue.
I’m wondering if I need to invest in an indexable carbide tool set for this piece.
Any suggestions?  


Chuck in E. TN
« Last Edit: May 28, 2010, 07:45:02 AM by Chuck in E. TN »
Chuck in E. TN
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Offline Trion

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Re: Rotary table
« Reply #30 on: May 28, 2010, 10:38:34 AM »
I'm a newb too. But blue chips from HSS tooling doesn't sound good. Hva you tried reducing the speed further? Or maybe smaller depths of cut?

Carbide tooling would probably help, but make sure you get tools that use positive rake inserts, they cut much easier than the zero rake inserts. Should make a differnce if you have already had issues with stalling the lathe.

Nice project btw. :thumbup:

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Re: Rotary table
« Reply #31 on: May 28, 2010, 10:47:23 AM »
Hi Chuck

As Trion said ,,,, Plus make sure if you lathe uses V-belts that they are tight , as slippage will cause poor finish and dig in , as the belt slips then re-grips ,,, you could if possible try and get the tail stock centre up to give the work a bit more support .

Regards Rob 

Offline Chuck in E. TN

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Re: Rotary table
« Reply #32 on: May 28, 2010, 11:46:42 AM »
What a difference a day or two makes! I took a couple days off the RT project to plant my veggie patch, and to think about the issues.
Today I started out using lighter cuts, and cutting oil. After again changing and honing bits, and using cutting oil, I managed to finish the registration face of the nose.



I still had some chatter, and even managed to stall the lathe a few more times, but progress was better. You can see the chatter marks in the pic, but I'm still in the function/fit mode rather than pretty mode.
Next, I’ll flip the nose over in the chuck and attack the undercut for the nuts to attach the faceplate or chuck. Then, transfer the bolt circle, drill and bore for the axel, counter bore for the washer and SHCS to hold the nose on the axel.
Chuck in E. TN
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MicroMark 7x14, HF X2 mill, Green 4x6 saw. Harbor Freight 170A mig

Offline Bernd

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Re: Rotary table
« Reply #33 on: May 28, 2010, 02:30:29 PM »
Chuck,

I'd get another piece of material. SOunds like you've checked all the possibilities. Have you tried another material to make sure it's not the lathe?

Bernd
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Offline Dean W

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Re: Rotary table
« Reply #34 on: May 28, 2010, 08:08:14 PM »
Hi Chuck;
Making some progress!
That chunk of steel you got hold of is probably common HRS (A36) or something like 1018 CRS.  Neither are very friendly to smaller
lathes.  They will surly cut fine, but smaller machines will want things to be "just so" to keep it from causing you headaches.
By the amount of chatter in your earlier pic of this stuff in the chuck, it could be the belt, like Rob says.  There are a number of other
things to check, like gibs and your tool height.  If your tool is truly sharp, then check the front clearance on it to make sure you have
enough.  Also, this kind of steel doesn't like to be plowed by the tool tip.  By that I mean, the side of the tool that travels toward the
chuck needs to be at less than 90° to the work piece.

If it's possible, try to use something other than the 80t gear.  Either 72, 60, 30, or 90 will give you an even division when you go to
make your graduated dial, and will  make your calculations much easier.  The 80t gear will give you 4½° per rotation.  Not handy at
all.  If you use 72t, it will give you an even 5° per turn of the hand wheel.  For 60t you get 6°, for 30 you get 12° and for 90 you get 4°.
Much handier to count up whole numbers when you go to index full degrees.   A 72t would probably be best, but you have a 60t there
and that would still work fine.
Just something to think about.

Thanks for the progress report!

Dean
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Offline Chuck in E. TN

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Re: Rotary table
« Reply #35 on: May 29, 2010, 07:15:03 AM »
More problems. While hogging metal off the spindle nose replica with a carbide tool from my inherited tool collection, the lathe started running rough, like a V8 with a loose spark plug wire…
I checked high and low range, same thing. Like someone was playing with the power switch, intermittent clunking and loss of power.
Since my lathe is a MicroMark with steel gears, I’m hoping it’s a bit of swarf in the gears somewhere. Today a tear-down and clean up, and I’ll see what’s up.
I like the idea of a 72 tooth gear, Dean, but I’m not yet set up for gear cutting. I’m wondering if it’s worth working out a system to be able to change the gears used. I’d have to come up with a way to move the worm in relation to the gear. Maybe the answer is to go with a 60 tooth.
Anyway, out to the shop for some lathe diagnostics…

Chuck in E. TN

PS: I seem to have trouble with previewing my posts here to check spelling, etc. When I hit preview, the post I composed disappears! I’ve gotten into the habit of composing the post in Word, copying and pasting to the post box. That way, if it disappears, I can do it again
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Offline andyf

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Re: Rotary table
« Reply #36 on: May 29, 2010, 08:04:30 AM »
Stick to a tooth count that divides into 360, Chuck. As has already been said, 80T will result in it being hard to keep track of your dial. 60T would be a good choice if you wanted to include a detent in the rotab for simple direct indexing, where it would work for dividing circles by 2,3,4,5,6,10,12,15,20 and 30. Out of all the numbers you are likely to need in direct indexing, only 8 is missing.

As to previewing posts, I think that normal operation is to compose your post, then click Preview and scroll up to see the preview pane above the toolbars containing all the smileys, dancing girls etc. You can't amend in the preview pane, but can scroll back down to the "compose" pane and make any adjustments before finally clicking on Post. Forgive me if this is too elementary, but are you scrolling back down again after previewing?

Andy
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I've cut the end off it twice, but it's still too short

Offline Chuck in E. TN

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Re: Rotary table
« Reply #37 on: May 29, 2010, 12:10:46 PM »
Well, the lathe is fixed. A thorough inspection revealed the gears are fine.
Checked the controller connections, as that was a problem before. They were all tight. Checked the motor brush on the front side, naturally the hardest to get to, and the cap holding the brush had broken again. Previously I had glued the halves back to gether. Both brush caps were cracked, so I replaced them. I had ordered spares after the last failure. Oddly, as hard as I have used this lathe, I could see no difference in the origional brushes, and the new replacements!
Put the machine back to gether and fired it up. Nothin! Power lights came on, no fault light, but no movement either.
Took the controller back off and checked all the connections again. Nothing loose. Reassembled and still nothing. Took the controller off again and checked for burned components. This time I noticed one lead of the 4K ohm power resister was broken. Got out the soldering iron and added a piece of wire for a repair.
Reassembled and the old girl came to life again. No bumps, thumps, as smooth as a Cadilac at idle! Back in business.

Chuck in E. TN
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Offline Chuck in E. TN

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Re: Rotary table
« Reply #38 on: May 29, 2010, 12:32:46 PM »
While troubleshooting my MicroMark 7x14 for jerky opperation, I found the controller (XMT-1135) had a lead broken on the Power Resistor. Anyone have the specs on this resistor? It's R17 on the board. I measured it with a multimeter at 3.84 K ohms. Color code is Orange, White, Red, Silver, indicating 3.9 k ohms at 10%.
What I need is the power rating.
My SWAG is (120vx120v)/3900 ohms=5 watt would be suffiient.

Chuck in E.TN
« Last Edit: May 29, 2010, 12:41:45 PM by Chuck in E. TN »
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Offline Chuck in E. TN

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Re: Rotary table
« Reply #39 on: June 01, 2010, 10:08:43 AM »
I continue to have trouble posting. I compose the post, and when I hit the post button it disappears!
Anyway, the Rotary Table is functioning! Rough as a cob, and needing a dial, scale, crank handle, clamps, and bearings added to the worm screw, but it works, and I built it! The first job was to drill the bolt circle for the spindle nose piece. I have torn it down and refined the registration face as it was a bit tight. But, the face plate, and chucks fit.
I will spend time refining it more, and I want to shorten the body by ¾”, shorten the spindle nose, and the spindle axis. I will probably remake the top plate also, as I had to offset it ¼” to fit the worm.
Here’s a video of it clamped to the mill table, and being rotated via my cordless drill.



Thanks to all those who commented, made suggestions, and provided moral support through this project.
And thanks especially to Dean for posting his excellent project that was my inspiration.

Chuck in E. TN
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Offline Dean W

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Re: Rotary table
« Reply #40 on: June 02, 2010, 12:21:20 AM »
Way to go, Chuck!
I really like this part:  "..but it works, and I built it!".  What a neat thing, huh?

I don't know about your resistor question. 
What kind of browser are you using to put up your posts?  I have Firefox, and it works like you'd expect.
When I hit the preview, the new post pops in above the box you type in.  Hope you get it figured out. 

I wish I knew how to get a Photobucket video to show up in the post the way you've done it.  Every time I
try that, it puts what looks like a video frame in the post, but when you click on it, it opens a new window in
Photobucket.  That bugs me!

Thanks for the update.  You sound happy!

Dean
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Offline madjackghengis

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Re: Rotary table
« Reply #41 on: June 02, 2010, 08:40:42 AM »
Hi Dean, a couple things, to get your postings down, go to my build log, the nine cylinder radial, in the beginning, as I had the same problems, and was aided very well by Cedge, who explained and demonstrated how to get pictures from photobucket posted with minimum problems, and real clarity.  With regard to tooth count, I would strongly echo all the advice, and stay away from that eighty tooth gear.  I'm satisfied with my table with seventy two, but would have prefered 90, looking back.  If you'd like, I can run a log on how to index a plate, and use it to cut a ninety tooth gear, or for that matter, a seventy two tooth.  When I had to make a couple of dials for a couple machines, I ran across a two hundred tooth plywood blade for a Skillsaw, and bought it for about three bucks, and made a simple indexing arrangement in my lathe spindle to index the dials with a hundred lines of three different lengths, if you found such a blade at Wally world or the like, that was a multiple of either 72 or 90, putting a blank on a spindle between centers on your mill, and cutting the teeth with a flycutter ground to fit the eighty tooth gear you have with some calculated "slop" to compensate for the slight difference in tooth count, you'd be in like Flynn.  If you can't, like I said, I'd be glad to lay out the means, and put it up in a log.  You are not going to want to redo this later, and if you use the eighty tooth gear, you will curse it often as you look back and still conclude you don't want to redo it, none the less, you will be happier with what you have, and doing it, than doing without because you don't have exactly what you want.  I almost made a rotary table with a 39 tooth worm wheel, but resisted for years because it would only be good with special calculations each and every time it got used.  Again, read through the beginning of my engine log and you'll find good clear instructions on putting up pictures and posting that work for this non-computer mechanic. :headbang: :lol:  mad jack

Offline Chuck in E. TN

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Re: Rotary table
« Reply #42 on: June 02, 2010, 11:06:53 AM »
Last night I turned a pair of bearing holders for the worm axil. Today I made a clamp set from 1 1/2" steel angle. and milled slots in the body of the RT to clamp it flat and vertical. I'll post pictures later.
Dean, I added the video to my post from Photobucket, just like adding a regular picture. I save the video from my camera to the album, I Clicked on the img code box and copied the code and pasted it into the post.
I don't know what it is about clicking preview, sometimes it works fine and my preview window apears above the post composition window, sometimes the post reply page just disapears.. Seems to disapear if I compose a long post directly without using word to compose and copy/past to the post window...
mad jack, I did go with the 60 tooth gear. Next, I think I will start over on the top plate, if I can figure out how to locate the bearing so the axil and thus the gear are positioned correctly to the worm.
So far, I have learned lots, broken a drill bit, a tap, and a 1/8 end mill. Material costs total $24, broken tools about $15, and I have a basic RT!
I'm really enjoying this!

Chuck in E. TN
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Offline Dean W

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Re: Rotary table
« Reply #43 on: June 03, 2010, 01:27:52 AM »
Hi Dean, a couple things, to get your postings down, go to my build log,

Hi Jack;  I don't have any troubles with stills and Youtube stuff.  It was the Photobucket Videos that didn't do right.  They put a frame in the post just like Chuck had in his earlier post with his R/T Movie, but when you click on them, it goes to Pbucket to show it.  It just bugged me!

Anyway, I think Chuck has me straightened out on that.  Thanks, you two!

Glad you settled on the 60t gear.  It will make things worlds better for you than that 80t beast!  It makes it more like using a lathe dial when the numbers all come out even.  Less chance to make a bad mistake trying to count half turns and all that nonsense.

I type up all my long posts for my project threads in Notepad, too.  Just in case...

Keep on having fun!

Dean
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Offline madjackghengis

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Re: Rotary table
« Reply #44 on: June 03, 2010, 08:39:17 AM »
Well Chuck, its good to hear you decided on the sixty tooth, I think it will make you happy in the long run, those little glitches like broken drills and taps don't matter much when the project works and meets the challenge you put before yourself, with success.  You'll probably spend more time making tooling and accessories for it, than you spent making the table its self, before you're done I wager.  I wish I had v-belts to worry about slipping, my flat belts slip all the time, and I'm looking at putting in a transmission from a lawn tractor so I can shift gears instead of deciding what pulley I want my flat belt to "slip on for this turning".  As far as the resistor goes, if it is about three eights long in the body, with coaxial leads and a color code, it is a quarter watt resistor.  If it looks the same only twice the size, as in a little longer in the body than half an inch, and with coaxial leads and color code on it, it's a half watt resistor.  If it's a power resistor with real current requirements/limitations, it will be a rectangular block of ceramic with a wire wound resistor inside, and ceramic goop fired across covering the wire, and its resistance and power rating would be printed on the "top" of the ceramic block.  If you have problems finding the right one, e-mail me, and I probably have one I can send you, being as you're in Tennessee, and just a few hours away.  By the way, if it is a quarter watt resistor, and it burned out, replacing it with a half watt would be a good idea.  I spent about thirty odd years in electronics so I probably have the parts you need, or at least know of easy access.  let me know, I'd be happy to help.  good job on the table, and good to see you have it under your belt, so to speak :mmr:  I like this club :headbang: mad jack