[vacpress]

http://cgi.ebay.com/ws/eBayISAPI.dll...category=11809


wadda you guys think?

[jimbo]

dont buy it there. saw the same thing at surplus center. http://surpluscenter.com/item.asp?UI...tname=electric

I bought one off ebay for 30 before I saw the one at surplus center. the table itself is pretty nice though.

[vacpress]

jimbo - do they work for rotary machining? how heavy duty is it?

could it be joints for a smallish robot arm? is it worth the $20 ?

backlash? speed? 4.5rpm?

could a bigger servo or a stepper be changed in?

how heavyduty does it seem?

[jimbo]

I dont have access to it now, maybe in a week I could get some pics of it taken apart. I would say it is definitely worth the 20 maybe more. It is a nice piece of machining, all aluminum body and steel gears. I would like to know its original application, it is much more than a turntable.

I have not actually used it yet because my router is not done. But I did power it up on 12v, it was smooth, quiet and unstoppable. I could not feel any discernible backlash but I am sure there is some present with the gears. It is too slow as is. The motor/gearbox can be unbolted but I believe the pinion is pressed on the gearbox and the gearbox shaft was some odd size like 3/16".

At some point I would like to put adapt a servo to it and flush mount this permanently into the table of a moving gantry router.

They would probably be perfect for robot joints although I dont know how small is possible, or perhaps as the base of the arm. I hadnt thought of that. Maybe I should pick some extras. Only 2700 in stock.

It seems quite heavy duty and rigid, from memory it had a big sealed bearing like 4" ODx3"IDx.75" D that the table rotates on.

let me know if you would like the pics later.

[jimbo]

also, only the center part rotates, it is like 3-4" dia, but with another plate bolted on it can be any size.

also surplus center says it has an encoder, it is not an encoder by normal terms. I believe it is just a tachometer or a 1ppr encoder. It does have a brake that can be tied to the motor supply to disable.

[Bloy2004]

I believe that those devices were for turning those bigger dish antenna that used to be seen often in back yards... I was one of the guys that got one for the higher price...then as the order was shipped, discovered the better deal at Surplus....oh well.

[boxwood]

Yeah this guy used 2 of those hooked together to make a 5 axis router... very impressive
http://www.rainnea.com/cnc.htm

[vacpress]

boxwood - that rainnea machine uses these things?

i think im sold... i also like the idea that its got brakes... perfect for robot arms... assuming i can get those cliftons to interface the things...


i mean.. a $30. high powered servo driven rotary joint with a brake built in... just gotta get a real encoder on the thing.... i mean.. its practically a breakthrough... for me.. anyhow...


plus, that rainnea machine is very very amazing

[jimbo]

the brake is on back of the globe motor so if you change to another servo you lose the brake.

I would also like to know if the rainnea machine really uses these units. They dont quite look the same.

[teilhardo]

I just bough one. I agree, for $30 it is well worth it. Even if one can't use it as a rotary table, the DC motor, gears and aluminum...all useful "junk" to have around the "shop"
-Tei

[vacpress]

yeah - i just looked at the rainnea machine again. those look like asian import 4" rotary machining table. those are like $100 without a motor or anything.

[georgebarr]

Does this item found at surpluscenter.com include the big rotary table and the motor? I can use this as a 4th axis for the lathe part of my mill.

Originally posted by jimbo
dont buy it there. saw the same thing at surplus center. http://surpluscenter.com/item.asp?UI...tname=electric

I bought one off ebay for 30 before I saw the one at surplus center. the table itself is pretty nice though.

[jimbo]

barr, I am not sure what you are asking. There is a picture on surpluscenter showing it, it is composed of the gearmotor and rotary table (if you can call it a table). It is also not that big, the outer mounting ring is approx 6" dia, the center rotary part to which you would to add a plate or lathe chuck to is approx 3-4" dia, surpluscenter states 4 holes at 2.79" bolt circle on the center piece. As I stated previously, it is too slow to use as is, due to the double reduction (4.5rpm output). It would take some work to adapt another servo or stepper to use instead. I will put it this way, it has potential. I am going attempt to use it as a 4th axis when I complete my router. But since I havent tried it I cant say it will work.

[jimbo]

boxwood, sorry, I doubted. I did find yahoo group post about it
http://groups.yahoo.com/group/CNC_To.../28?threaded=1

[vacpress]

Ah. a perfect answer!

So it has backlash, it is very cheap. it can work! it is cheap. it isnt perfect.


it sounds pretty nice for my robot arm though..

my poor bank account. poor poor bank account.

"There's a couple of pictures under "4th & 5th Axis Unit" in the
photos section. I just used some 80 x 80 x 8mm L-bracket and bolted
this to the backs of the rotary units although a more solid
arrangement would be preferrable."


wow. raineas machine is much more modestly machined that i thought at first!

[teilhardo]

What encoders did rainnea replace for the Hall sensors?
Does anyone have any advice on what stepper motors to use? Would 64oz/in be enough?

[vacpress]

teilhard -

heres a hint - in trashed printers, espeically more expensive ones, there are lots of goodies like encoders, servos, steppers.. if getting broken printers sounds hard - try this: start calling all the printer repair places near you. tell them your a highschool student and you need broken printers for engineering projects. if you call 5 places, i bet you will get at least 1 success.

my parents own a repair shop and toss like 5-20 printers a month...if i got all of them - i would have nowhere to live.

some examples:

older Oki dotmatrix printers have the most goodies:
1 large stepper, 1 24v 1amp servo with dif encoder, usually 2 small steppers, a toothed belt, a SS shaft, a powersupply, etc.

HP IIs are the easiest to get. they have a decent main motor, a bunch of IR sensor pairs, a stepper driver, a power supply, bunch of springs, some useable screws & bolts...

HP Inkjets: there are easy to get also: they have - a cool encoder, or 2, a decent steel shaft, some neat rollers, a female USB plug, a bipolar driver IC, a power jack.

other equipment can be good also. ive heard of people getting old vending equipment, food packaging, welding, etc. for free or nearly free, and getting all kinds of great goodies out...

good luck - if you really need help, i could send you some carcasses, for the cost of shipping. something like 2 inkjets and a HP series II could be a godsend for someone without any spare parts.

[teilhardo]

I've got an old inkjet printer that I scrapped, found some steppers but they are the small, pancake type. Do you think these will be powerful enough?

[teilhardo]

Thanks for the offer to ship, fortunately I have a surplus place pretty close, but without a car its kind of hard to get to...

[vacpress]

well. for some things. if you drop them into that rotary - they will be powerfull enough because of the gearing - but they might not even hit the 4.5rpm those tables listed. id imagine that those DC motrors on the rotary table prolly spin at like 1400-2500rpms with the turntable load? sooo. you probably will be looking at either a very slow, but poitionable table, or probably you will want to gut the thing and use toothed belts or something... i would look for bigger and more broken printers. some big copiers have retarded amounts of machinery in them.. get out that phone book. OR

gotta car? find a list of the 10 closest repair places and go check their dumpsters. my parents toss tons of stuff in the dumpster... i tell them not to - they do it anyways.,..