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| Rotary table help or advice please |
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| 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 |
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