Rotary table help or advice please

[murphy555]

hi all
       i really need some help or advise regarding rotary tables i am not a very good engineer but i try hard i suppose i am a keen amateur
my problem is i wanted to make a couple of 90 degree plates to angle a table for a sander and also make an adjustable angle plate for use on the mill whilst i managed to make said plates using a couple of cheap rotary tables i also managed to bugger up the gears in the rotary tables
question is should i have disconnected the gears and moved the tables manually i think i probably should have but my understanding was i would be able to just mount the plates set them up and mill the angles required

the material was used was only 3mm mild steel plate for one and the other was 4mm aluminium the slots were only 5mm and 6mm hardly heavy graft the mill is a raglan the tables were bolted down and sacrificial plates were used under the plates
i'm more annoyed at the rotary tables being buggered up
and before anyone suggests i just make new gears like i said i am a crap engineer who can't even screw cut properly
sorry to be so long winded about this but any help or advice would be appreciated i look at all the things and projects everone else submits with a high degree of envy thanks in advance

[vtsteam]

Murphy, I'm not sure why you needed rotary tables to make angle plates. But perhaps there was a partial rounded section or rounded slots? If working a straight line at an angle, was there a lock on the table?

I make 90 degree angle plates themselves on the lathe faceplate, using the method of bolting them together (like a Z) with shims between the faceplate and first angle to get it square, and facing the outer one of the pair.  Then reversing without shims and facing the other. Then re- bolting the good sides together and facing the other pair of sides.

You can buy gears if you don't feel comfortable making them.

Maybe also introduce yourself in the welcome section? 

[chipenter]

Did you release the lock on the RT , and is there adjustment to push the worm into the wheel ?

[murphy555]

please find attached pics

[vtsteam]

Murphy, if you want people to help you, you're going to have to answer their questions and provide information. You have the tables and work, and know how you performed your work. We don't.

Also your photos are way too large (please post photos 800 pixels wide or less) and there's no information to go with them. What are we looking at? The gear is blurry. I see a rotary table and two milled parts.

All I can say at this point is what you already know. You somehow exceeded the capacity of what you call cheap rotary tables. How you did that, what your procedures were, what cutters you used, what their condition was, how much material you tried to cut at a time, whether the parts were doubled up to cut, what the clamping procedure was, cutting depth, speeds and feeds, or whether the tables (brand, size, condition?) were faulty and so caused the damage, we can't tell from the information provided.

Sorry this happened to you. But your guess is not only as good as, but better than ours at this point.

[murphy555]

sorry i was not thinking straight at the time i will try and enclose the pictures again but photo manipulation is not my strong point and i don't know how to resize the photos to 800 pixels

the photos of the plates are what i was trying to achieve and did at an obvious cost to the rotary tables

in my lack of knowledge i thought to create the plates all i had to do was centre the tables bolt down the plates to the tables and cut the grooves in them using the rotary tables the first set were doubled up the material was 3mm mild steel the cutter was 5mm and brand new the mill is a raglan and the speed was about 300rpm cuts were very light about 5-10 thou some cutting oil was used no support was used between the tabe and the plates i realise now i should have fixed  the plates  better but again lack of knowledge   i just did not know any better i also realise now that what i was doing was wrong
ie i was winding the table both ways ie climb milling and conventional milling obviously not a smart thing to do which probably caused the destruction of the table gear the rotary table used was a 75mm table i also realise now that i should have removed the worm assembly and manually moved the rotary table but did not realise the damage i was about to cause or i would not have done it once again lack of knowledge i am not an engineer i am more electrical biased but like engineering i have lots of tooling and its cost me a lot of money no wonder i hear you say the way i destroy rotary tables but i am getting tired now so will continue this saga tomorrow

[vtsteam]

Okay that's a lot clearer and It's a sad thing to have happen!

Chipenter asked if you had an adjustment to bring the worm and wheel together, and whether the brake had been on.

I'm still curious about the brand of the tables.

My only experience with a rotary table is with the one I made which uses a Tommy bar, not a worm and wheel. I do have a worm and wheel ancient heavy dividing head that was designed to be mechanically turned in a mill. Others can comment about rotary tables for that kind of application..

[PekkaNF]

I have a HV6 (150 mm) rotab. I routinely use it for "circular milling" and rounding off. Pretty soon when I got it, I disassembled and cleaned it (least twice). I had some crud inside and needed some fitting. These rotabs are not really as strong as old properly build ones. It's very importat to get tooth contact close to correct, but it's almost impossible to get it very good, because build quality is not that great.

I have done 60 mm dia hole in 30 mm thick aluminium plate using 10 mm slot drill. Doing was pretty slow but not extremely slow.
http://madmodder.net/index.php/topic,5041.0.html

I tried to mill teeths of welded chanin sprocet wheel....something like 30mm thick and 170 mm diameter and that was not happy going even when rotab was locked.

How did it fail? Did something crab the the mill and rotab failed catastrophically? Or did it disintegrated gradually while you we cranking it?

Pekka

[Meldonmech]

Hi Murphy

                  1. Using the rotary table :  Do not use this device unless the worm and wheel are fully engaged, lubricated and running freely.   Never use manually with the table disengaged.   Never climb mill.  Always positively support the workpiece, and securely clamp it.  I use a 10 inch dia. piece of 3/4 inch plywood made from hard wood, bolted to the table, when cutting circular slots as you describe.
                  2.  Cutting Speeds for Milling Cutters :  The cutting speed for mild steel for a cutter the size used 5mm should be at least 1000rpm and for aluminium much faster than that.  Before carrying out any more machining operations you must aquire  more basic knowledge, you could have a serious accident.  Here is a website on  Milling : Cutting Speeds and RPM Calculations, which in your case is a must read.  its.foxvalleytech.com___ Download and keep for reference.
                  3.  Cutting Fluids : Different material require different cutting fluids, and some none at all.  Aluminium requires WD40 or parrafin, to avoid aluminium building up on the cutting edge of the milling cutter.
                  4. Cutting Feeds :  Feeds depend on the material being cut (cutting speeds) and the number of teeth on the cutter, the more teeth the cutter has the faster the feed can be.

                   I believe the teeth on you worm wheel sheared due to build up of pressure due to a combination of problems, referred to in the incorrect uses of the items as detailed above.

                    Do not feel despondent about some of the projects seen on this forum.  In most cases these have been completed by members having many years of experience.

                                            Good Luck     David



               

[PekkaNF]

Very good advice from David.


One more aftertought: If you feel that the rotab is a write off, don't chuck it away. You might be able to use the "table" part on something like this:
http://www.projectsinmetal.com/a-simple-rotary-table-without-a-worm-drive/

We all break some stuff. Main thing is no-one is hurt. My milling machine is about 1500 kg and has about 3 KW motor: I have managed to strip clean all tooths of one over 35 mm T-slot cutter on automatic feed because the piece moved....you should have heard the bang and see me jump out of my skin. Once I bough new solid carbide mill and even before using it ONCE I dropped it on concrete floor - business end firs. Hurt even more my pride than wallet. I did down milling before I got any experience....it produced some artwork and much wreked parts and mills. Don't get too worked out from the crashes. Keep safe and calm.

Do you have any books of the subject? I can recommend  Milling: A Complete Course (Workshop Practice) by Harold Hall (Author).
This is pretty hands on and nice thing about is that you build some usefull acessories for the milling machine while learning.
http://www.homews.co.uk/page505.html

Also his site is very informative, but projects needs some experience.
http://www.homews.co.uk/page463.html

Pekka

[murphy555]

first i must thank everyone for the advice given

i don't normally ask for help ussually just plod on i have never contacted any forums hence i don't know about resizing pictures or the amount of information required when asking for help but i do now

now to continue with part 2 of the saga

the first rotary table was only a week old it was cheap only £45.00 in the uk i'm assuming most of the replys from you guys are from the usa it's the type of r/t supplied by grizzly and harbour freight it was a 75mm table with a bronze gear when i contacted the seller it was immediately replaced so it was not a total loss but don't know if i could trust it for anything important

let me give you all a little of my background
i'm not young in fact i'm 69
i'm retired
i was a service engineer for many years
i collected all the tooling i have over many years for my retirement
i have had 1 heart attack and 2 strokes and am supposed to be a diabetic
don't really think any of the above is relevant

my workshop/garage is small no real large tools

my mill is a raglan which is quite small i could not get away with a 6 inch rotary table anyway i diverse

back to the second r/t after my first attempt at making the plates which sort of worked all be it at a cost
i decided to make a bigger set of plates with my other r/t which was a kit purchased a while back it had a steel /cast gear which i thought would be stronger and be able to handle the pressures better but that was not to be

this time i used a piece of hard wood between the table and the work fixing them securely

this time i used aluminium plates and again worked but at a cost ie the gear was destroyed but since then have as was suggested by pekka i then converted the table to be used  without the worm drive i can use a tommy bar

once again thanks to everyone i really appreciate all your replies
thanks
        charlie m

[Pete W.]

Hi there, Charlie,

Welcome to Mad Modders.

I suggest that you go into the 'Gallery' section where you will find a thread about resizing photos using Faststone resizer.  You can download faststone free and install it on your computer.  Then launch it and explore the various options and facilities until you get the hang of it.  Resizing photos is only one of its capabilities - you can also add captions, labels and watermarks etc.

If you have a look at my 'Pete's Tin Shed Project' thread, I put all the photos through Faststone before hosting them on Photobucket.

Just give it an hour or two at the keyboard and I'm sure you'll soon get the hang of it.          

Believe me, it really does kill the reader's interest and enthusiasm when poster's photos are about seventeen times the reader's screen width!!          

My own projects have been stalled for domestic reasons for a few months but before that I posted fairly regularly and I was pleased with all the help, encouragement and interest I received - I'm sure you will find the same. 

[vtsteam]

Charlie, as you can see, you're in the right place here. Very glad you joined and asked questions. And it looks like you already got the knack of resizing and captioning photos with the second set. Looks like you even vignetted them!  You're a quick study.

I hope you'll stay and post more questions, as well as show what you're up to in your projects, and even help out other newer-comers when you feel you can.

We like hearing about the your background details and your interest in machining and experience -- usually people start out with that in the introductions section of the forum. And you're certainly not alone in terms of your age, etc! So welcome, here, to MadModders

[murphy555]

thanks again for all your comments and if i can help out in any way i will certainly do so
cheers
         charlie m